A dynamic artificial gastrointestinal system for studying the behavior of orally administered drug dosage forms under various physiological conditions

PURPOSE

The purpose of this study was to demonstrate the potential of a dynamic, multicompartmental in vitro system simulating the human stomach and small intestine (TIM-1) for studying the behavior of oral drug dosage forms under various physiological gastrointestinal conditions.

METHODS

Two model drug compounds were studied in TIM-1: a lyophilized Lactobacillus strain and paracetamol (acetaminophen). The Lactobacillus survival rate was determined by bacterial counting in the gastric and ileal effluents while simulating the conditions of the gastrointestinal tract of infants or adults. The availability for absorption of paracetamol from two oral dosage forms was investigated by measuring the drug concentration in jejunal dialysis fluid. The effect of gastrointestinal passage time and food intake on paracetamol absorption was also studied.

RESULTS

The Lactobacillus survival rate in both gastric and ileal effluents was higher during simulation of the infant compared to adult conditions. We also showed that (i) paracetamol absorption was faster when it was administered as a free powder than in sustained-release tablet form, (ii) a slow passage time resulted in a delay in the absorption of paracetamol, and (iii) there was a lower rate of absorption when paracetamol was ingested with a standard breakfast as opposed to water. The in vitro results were consistent with in vivo data, showing the predictive value of TIM-1.

CONCLUSIONS

TIM-1 is a powerful tool for supplying valuable information about the effects of various gastrointestinal conditions on biopharmaceutical behavior and efficacy of drug delivery systems in the development of oral formulations.

Frequency and impact of allergic rhinitis in asthma patients in everyday general medical practice: a French observational cross-sectional study

BACKGROUND

Allergic rhinitis (AR) and asthma are inflammatory conditions of the airways that often occur concomitantly. This observational, cross-sectional, national study was undertaken to describe the frequency and severity of AR in asthmatic patients. The impact of AR on the quality of life and the therapeutic management of patients in everyday general medical practice were also assessed.

METHODS

From April to October 2005, 1906 French general practitioners (GP) participated in the study. Each physician had to fill out a questionnaire (including the Juniper Asthma Control Questionnaire and a Rhinitis Questionnaire) for up to 10 consecutive adult asthmatic patients. The first three patients with a confirmed diagnosis of AR (Allergic Rhinitis and its Impact on Asthma classification) were asked to complete the Juniper Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ).

RESULTS

A total of 14,703 patient questionnaires and 4335 auto-questionnaires were analysed. Patients presented with intermittent (45%), mild (25%), moderate (25%) and severe (4%) persistent asthma. The frequency of AR in asthmatic patients was 55.2% (CI: 95%, 54.4-56.0%). Allergic rhinitis was mild for 54% and moderate/severe for 46% of patients. The frequency and severity of AR increased with the severity of asthma (P < 0.001). Moreover, AR was associated with worse asthma control whatever be the severity of asthma (P < 0.001). The global RQLQ scores of AR patients worsened with the severity of asthma (P < 0.001). Prescription of anti-asthma treatments significantly increased with the severity of AR. The majority of AR patients (81%) were treated for rhinitis.

CONCLUSIONS

This survey suggested that AR was associated with more severe asthma, more difficulty to control asthma and substantial impairment of quality of life. The high frequency of AR in asthma patients requires that these conditions should be recognized and managed by GP.

Recombinant Saccharomyces cerevisiae expressing P450 in artificial digestive systems: a model for biodetoxication in the human digestive environment

The use of genetically engineered microorganisms such as bacteria or yeasts as live vehicles to carry out bioconversion directly in the digestive environment is an important challenge for the development of innovative biodrugs. A system that mimics the human gastrointestinal tract was combined with a computer simulation to evaluate the survival rate and cinnamate 4-hydroxylase activity of a recombinant model of Saccharomyces cerevisiae expressing the plant P450 73A1. The yeasts showed a high level of resistance to gastric and small intestinal secretions (survival rate after 4 h of digestion, 95.6% +/- 10.1% [n = 4]) but were more sensitive to the colonic conditions (survival rate after 4 h of incubation, 35.9% +/- 2.7% [n = 3]). For the first time, the ability of recombinant S. cerevisiae to carry out a bioconversion reaction has been demonstrated throughout the gastrointestinal tract. In the gastric-small intestinal system, 41.0% +/- 5.8% (n = 3) of the ingested trans-cinnamic acid was converted into p-coumaric acid after 4 h of digestion, as well as 8.9% +/- 1.6% (n = 3) in the stomach, 13.8% +/- 3.3% (n = 3) in the duodenum, 11.8% +/- 3.4% (n = 3) in the jejunum, and 6.5% +/- 1.0% (n = 3) in the ileum. In the large intestinal system, cinnamate 4-hydroxylase activity was detected but was too weak to be quantified. These results suggest that S. cerevisiae may afford a useful host for the development of biodrugs and may provide an innovative system for the prevention or treatment of diseases that escape classical drug action. In particular, yeasts may provide a suitable vector for biodetoxication in the digestive environment.

Compliance to oral nutritional supplementation decreases the risk of hospitalisation in malnourished older adults without extra health care cost: Prospective observational cohort study

BACKGROUND & AIMS

Malnutrition affects 5-10% of elderly people living in the community. A few studies suggest that nutritional intervention may reduce health care costs. The present study included malnourished elderly patients living at home. It aimed to compare health care costs between patients that were prescribed ONS by their general practitioner and those who were not, and to assess the effect of ONS prescription on the risk of hospitalisation.

METHODS

This prospective multicentre observational study included malnourished patients ≥70 years old who lived at home. Patients were defined as malnourished if they presented with one or more of the following criteria: weight loss ≥5% in 1 month, weight loss ≥10% in 6 months, BMI <21 kg/m², albuminemia <35 g/L or Short-Form MNA ≤ 7. Their general practitioners prescribed an ONS, or not, according to their usual practice. Health care costs were recorded during a 6-month period. Other collected data were diseases, disability, self-perception of current health status, quality of life (QoL), nutritional status, appetite and compliance to ONS. A propensity score method was used to compare costs and risk of hospitalisation to adjust for potential confounding factors and control for selection bias.

RESULTS

We analysed 191 patients. At baseline, the 133 patients (70%) who were prescribed ONS were more disabled (p < 0.001) and had poorer perception of their health (p = 0.02), lower QoL (p = 0.04) and lower appetite (p < 0.001) than the 58 patients (30%) who were not prescribed ONS. At 6 months, appetite had improved more in the ONS prescription group (p = 0.001). Weight change was not different between groups. Patients prescribed ONS were more frequently hospitalised (OR 2.518, 95% CI: [1.088; 5.829] hosp; p = 0.03). Analyses of adjusted populations revealed no differences in health care costs between groups. In the ONS prescription group, we identified that health care costs were lower (p = 0.042) in patients with an energy intake from ONS ≥ 500 kcal/d (1389 ± 264 €) vs. < 500 kcal/d (3502 ± 839 €). The risk of hospitalisation was reduced 3 and 5 times when the intake from ONS was ≥30 g of protein/day or ≥500 kcal/d, respectively.

CONCLUSIONS

ONS prescription in malnourished elderly patients generated no extra heath care cost. High energy and protein intake from ONS was associated with a reduced risk of hospitalisation and health care costs.

Evaluation of a dynamic in vitro model to simulate the porcine ileal digestion of diets differing in carbohydrate composition

The aim of the study was to assess the ability of a dynamic in vitro model to determine the digestibility of OM, CP, and starch compared with a validated, static, in vitro method and in vivo ileal digestibility obtained from growing pigs fitted with a T-cannula. Five experimental diets with different carbohydrate types and level were assessed: a standard corn-based diet (ST) or the same diet with coarse ground corn (CC), 8% sugar beet pulp (BP), 10% wheat bran (WB), or 8% sugar beet pulp and 10% wheat bran (HF). In the in vivo experiment, diets CC and HF reduced (P = 0.015) ileal digestibility of OM compared with the ST diet. The inclusion of sugar beet pulp reduced (P = 0.049) ileal CP digestibility of the BP diet. This reduction was not statistically significant when sugar beet pulp was combined with the wheat bran in the HF diet. No differences were shown for in vivo starch digestibility among diets. With the static in vitro method, the OM disappearance was greater than that observed in the in vivo experiment. In this static method, the BP and HF diets reduced (P = 0.004 and < 0.001, respectively) the disappearance of the OM compared with the ST diet. The coarse grinding of corn did not alter OM digestibility but decreased (P = 0.005) the starch digestibility. The R(2) between the in vivo results and the static in vitro methods for OM and starch digestibility was 0.99 when the CC diet was not considered. The dynamic in vitro model yielded OM and CP digestibility coefficients comparable with those obtained in vivo for the ST and CC diets. However, the values were considerably affected by the incorporation of the fibrous ingredients. Diets BP, WB, and HF had decreased (P = 0.009, 0.058, and 0.004, respectively) OM digestibility compared with the ST diet. Protein digestibility was also decreased (P < 0.001, P = 0.019, and P = 0.003, respectively) with the BP, WB, and HF diets compared with the ST diet. However, digestibility was decreased to a greater extent in the BP diet than in the WB and HF diets, both of which contained wheat bran. The R(2) between the dynamic in vitro model and the in vivo results for CP digestibility was 0.99 when the CC diet was not considered. No differences were detected for starch digestibility among the diets with the dynamic in vitro model. This dynamic in vitro model yielded ileal digestibility results comparable with those obtained in vivo for CP and OM with a corn-soybean diet, or with a diet including coarse corn, but it underestimated digestibility when fibrous ingredients were included in the diet.

Use of active shunt for surgical repair of intrapericardial inferior vena caval injury

We report a case of intrapericardial inferior vena caval disruption due to goring by a bull, and we describe the surgical repair of this uncommon penetrating cardiac injury. Review of the literature indicates that, as with other penetrating cardiac injuries, this rare lesion requires aggressive treatment involving an emergency thoracotomy. The use of an atrial caval active shunt was necessary for successful surgical management, and therefore we conclude that surgical treatment of this lesion is comparable with surgical repair of hepatic veins and retrohepatic vena caval injuries incurred during blunt vascular trauma or penetrating abdominal injuries.

Significant improvement of androgenetic haploid and doubled haploid induction from wheat plants treated with a chemical hybridization agent

A very significant improvement of the total yield of androgenetic green plants after anther culture is presented. The process involves treatment of the donor plants by spraying at different stages around the meiosis with a chemical hybridization agent (CHA) solution, fenridazon-potassium. When harvested at the normal uninucleate pollen grain stage, anthers have shown during in vitro culture very significant increases in embryo production. Compared to the control, we observed up to a 20-fold increase in the production. Moreover, when cultivated later, anthers still remained embryogenic. Therefore the process appears to be very efficient and to allow a broadening of the target period for androgenesis in vitro. The regeneration was not disturbed by the CHA treatment and, as shown in this paper, the technique seems to be applicable to a large range of genotypes. Cytological observations revealed both a low frequency of aneuploidy among the regenerated plants and peculiar features in the pollen grain walls after treatments; a triploid plant was observed. Hypotheses to explain the phenomenon are presented and related to previous observations on the effects of gametocide substances like ethrel, male sterility and pollen dimorphism on androgenesis.

Cardiac pheochromocytoma

Primary pheochromocytomas of the heart are extremely uncommon. In this report, we present the case of a patient with primary cardiac pheochromocytoma arising from the interatrial septum. Metaiodobenzylguanidine-scintigraphy was negative and diagnosis was confirmed by a positive octreotide scintiscan. The tumor was removed successfully using cardiopulmonary bypass.

Beam-propagation method based on the Wigner transform: a new formulation

A new formulation of the classical scalar beam-propagation method is derived by use of the Wigner transform. The new method is faster than the classical beam-propagation method because no Fourier transform must be computed. An example given to illustrate the proposed method shows additional advantages.

Implementation of the spatial and the temporal cross-ambiguity function for waveguide fields and optical pulses

On the basis of space-time duality, we propose experimental setups to implement the cross-ambiguity function optically in space and time in one and two dimensions. In space the cross-ambiguity is shown to be related to the coupling efficiency between butt-joined optical waveguides. In time it is related to the spectrogram or the frequency-resolved optical gating techniques for the characterization of optical pulses.

[Value of the superior trans-septal approach in mitral valve replacements]

Mitral valve exposure is widely improved by the superior-transseptal approach (STS). The diffusion of this technique has been restricted because of the possibility of detrimental effects of sino-atrial arrhythmias, especially in patients in sinus rhythm preoperatively. Between April 1991 and December 1992, we performed mitral valve replacement (MVR) on 55 patients by an STS approach. The mean age was 57.7 +/- 11.3 years (38-75 years). 21 were reoperations and 1 patient had been operated twice. The procedure consisted in 10 MVR with a bioprosthetic valve and 45 with a mechanical valve. Associated procedures were 5 tricuspid annuloplasties, 13 aortic valve replacements, 1 tricuspid valve replacement, 4 CABG, and 1 aneurysm resection. Overall hospital mortality was 9.1 +/- 3.8% (5/55). Mortality for isolated MVR was 6.2 +/- 4.2% (2/32). 51% (28/55) were in sinus rhythm (SR) preoperatively, 43% (12/28) of them had never presented atrial fibrillation. Postoperatively among those 28 patients in SR, 20 remained in SR, 7 were in atrial fibrillation, and 1 in atrial flutter. 3.6% (2/55) needed transient electrosystolic pacing for very slow atrial fibrillation 20% (11/55) have presented a transient sino-atrial dysfunction; None of these rhythmic events had any adverse effect. Finally, the very good visibility and accessibility are the major advantages of this approach, especially in mitro-tricuspid combined procedures, in small left atrium and repeat surgery. As sino-atrial arrhythmias are transient, we think this approach can be routinely employed in MVR.

Traumatic aortic regurgitation: aortic valvuloplasty controlled by aortoscopy

Traumatic aortic insufficiency is a rare occurrence after blunt chest trauma, and requires surgical treatment. Aortic valve replacement has been proposed as the procedure of choice, but primary valve repair is being performed increasingly more often. In a plead for conservative surgery, we report a case of valvuloplasty that was controlled by intraoperative aortic endoscopy. When operative conditions permit aortic valve repair, this should be carried out in order to avoid aortic valve replacement and its potential complications, especially in young patients with healthy valves. Replacement is the safest treatment for complex or multiple injuries of the aortic valve, however.

One-step measurement of optical fields in multimode circular fibers

We propose to determine the optical field in multimode circular fibers by using a one-step method that measures the Wigner distribution function of a section of the field in the fiber. This method allows an estimation not only of the power carried by each mode but also of the relative phases of different modes in the fiber. An additional measurement with the same setup can even determine the propagation constants of different modes. An example is provided, and the connection of this method of field recovery to the coupling coefficient between fibers and light sources is also discussed.

Recovery of the refractive-index profile from the wigner distribution of an optical waveguide

We propose a new method for the recovery of the refractive-index profile of a single-mode or multimode optical guided structure. We solve the inverse problem using the Wigner distribution and reduce it to the solution of a linear system of equations.

[Traumatic aortic regurgitation: diagnostic, management and treatment]

Traumatic aortic valve regurgitation is a rare complication of non-penetrating thoracic trauma. The most frequent lesion is the isolated injury of the non-coronary cusp. Actually, the transoesophageal echocardiography is the procedure of choice to confirm the diagnosis and to reveal the associated cardiovascular lesions. Surgical management with early operation is the best policy, however this surgery can be delayed for treatment of other life-threatening injuries. Up today, aortic valve replacement (AVR) was recommended to repair traumatic aortic valve regurgitation; nevertheless, in the recent international literature, the number of cases reports with conservative surgery (CS) is increasing: 10 AVR (group I) and 10 CS (group II). Analysis of the post-operative and long term periods shows good results: it confirms the excellent clinical evolution in the group I (mean time of follow-up: 18.2 +/- 16.3 months), and reveals satisfactory results in the group II for patients with isolated lesion (mean time of follow-up: 29.1 +/- 30.7 months). In conclusion, each time the traumatic aortic regurgitation is due to an isolated lesion, the conservative surgery should be performed in order to avoid aortic valve replacement and its potential complications especially in young patients with healthy valves. However, the aortic valve replacement is the safest technique for complex or multiple injuries of the aortic valve.

Fracture embolization of a Tekna mitral prosthesis: case report

The modified Duromedics-Tekna bileaflet pyrolitic carbon mechanical prosthesis was reintroduced by Baxter in 1990. This report details the first case of sudden leaflet fracture of a Tekna mitral valve five years after implantation, which was managed successfully by replacement with a St. Jude Medical mechanical prosthesis. The fracture had occurred transversely, with the fragments embolizing to the terminal aortic bifurcation and the left common femoral artery. These were localized by computed tomography and removed two days after valve replacement.