Pharmacokinetics/pharmacodynamics of antipseudomonal bacteriophage therapy in rats: a proof-of-concept study

OBJECTIVES

Pan-drug-resistant (PDR) Pseudomonas aeruginosa is one of the three top-priority pathogens identified by the WHO, and bacteriophages have been investigated as an alternative therapy. However, knowledge on the pharmacokinetics/pharmacodynamics (PK/PD) of phage therapy is sparse, limiting its clinical applications. This study aimed to evaluate the PK/PD of the antipseudomonal phage øPEV20 in vivo following intravenous administration.

METHODS

Healthy Sprague-Dawley rats were given øPEV20 as a single intravenous bolus of ~6, 9 and 11-log₁₀PFU/rat. Arterial blood was sampled over 72 h. At 72 h, the animals were killed and multiple tissues were harvested for biodistribution studies. A PK model was developed using the importance sampling algorithm and deterministic simulations with a PD model were performed.

RESULTS

A three-compartment model with non-linear clearance described the exposure of øPEV20 in blood. Model evaluation indicated that the model was robust and parameter estimates were accurate. The median (standard error) values of model-predicted PK parameters for V_C, V_P1, V_P2, Q₁, Q₂, V_m and K_m were 111 mL/rat (8.5%), 128 mL/rat (4.97%), 180 mL/rat (4.59%), 30.4 mL/h/rat (19.2%), 538 mL/h/rat (4.97%), 4.39 × 10¹⁰ PFU/h/rat (10.2%) and 1.64 × 10⁷ PFU/mL/rat (3.6%), respectively. The distribution of øPEV20 was not homogeneous; there was preferential accumulation in the liver and spleen. Deterministic simulations with a PD model confirmed the importance of the host immune system in facilitating phage-mediated bacterial elimination.

CONCLUSIONS

We developed a robust PK model to describe the disposition of phages in healthy rats. This model may have significant potential in facilitating future preclinical and clinical PK/PD investigations.

Randomised clinical trial: high-dose vs. standard-dose proton pump inhibitors for the prevention of recurrent haemorrhage after combined endoscopic haemostasis of bleeding peptic ulcers

BACKGROUND

The optimal dosage of intravenous proton pump inhibitors (PPIs) for the prevention of peptic ulcer rebleeding remains unclear.

AIM

To compare the rebleeding rate of high-dose and standard-dose PPI use after endoscopic haemostasis.

METHODS

A total of 201 patients with bleeding ulcers undergoing endoscopic treatment with epinephrine injection and heater probe thermocoagulation were randomised to receive a high-dose regimen (80 mg bolus, followed by pantoprazole 8 mg/h infusion, n = 100) or a standard-dose regimen (pantoprazole 40 mg bolus daily, n = 101). After 72 h, all patients were given 40 mg pantoprazole daily orally for 27 days.

RESULTS

There were no statistical differences in mean units of blood transfused, length of hospitalisation ≦5 days, surgical or radiological interventions and mortality within 30 days between two groups. Bleeding recurred within 30 days in six patients [6.2%, 95% confidence interval (CI) 1.3-11.1%] in the high-dose group, as compared to five patients (5.2%, 95% CI 0.6-9.7%) in the standard-dose group (P = 0.77). The stepwise Cox regression analysis showed end-stage renal disease, haematemesis, chronic obstructive pulmonary disease (hazard ratio: 37.15, 10.07, 9.12, 95% CI: 6.76-204.14, 2.07-49.01, 1.66-50.00 respectively) were independent risk factors for rebleeding and Helicobacter pylori infection was associated with lower risk of rebleeding (hazard ratio: 0.20, 95% CI: 0.04-0.94).

CONCLUSIONS

Following combined endoscopic haemostasis of bleeding ulcers, co-morbidities, haematemesis and H. pylori Status, but not PPI dosage, are associated with rebleeding (http://www.Clinical Trials.gov.ID: NCT00709046).

Automatic control of mechanical forces acting on cell biomembranes using a vision-guided microrobotic system in computer microscopy

A prototype for automatic control of mechanical forces acting on cell biomembranes is proposed in this paper. This prototype consists of vision-guided position control of the holder and micro-force sensor, automatic mechanical property characterization of cell biomembranes and automatic control of mechanical forces acting on cell biomembranes. A template-free calibration method and autofocusing of multiple objects are introduced in the vision-guided position control to minimize external biological contamination and position the cell, holder and micro-force sensor into the same focal plane, respectively. A third-order polynomial modified from biomembrane point-load model describing the relationship between the measured mechanical force and the deformations of biomembranes is proposed. This simplified model is easily identified and inversed to facilitate the automatic control of mechanical forces. Experimental results based on zebrafish embryos demonstrate the feasibility of the proposed prototype.

Self-calibration method for vision-guided cell micromanipulation systems

A new self-calibration method for a piezoelectric actuator-based vision-guided cell micromanipulation system is proposed. This method consolidates all the system parameters' uncertainties into a matrix instead of classifying into intrinsic and extrinsic. The position difference of the micromanipulator tip in the image plane between the measured and estimated output which is based on estimations of relevant parameters is assumed to be caused by the matrix. This matrix is estimated by means of collecting several pairs of known input and the corresponding output differences. Matrix standard deviation and gray-value based matching are applied to identify the output differences. Biological contamination is reduced since a calibration template is not required. This self-calibration is particularly suitable for cell micromanipulation systems where the micromanipulator is frequently dismounted and mounted.

[Plant regeneration from Agobacterium-mediated CTV-cp gene transformation of Poncirus trifoliata Raf]

OBJECTIVE

To lay a foundation for the resistant breeding, the anti-virus CTV-cp gene was transformed into the epicotyles mediated by Agrobacterium tumefaciens in Poncirus trifoliata.

METHOD

The explants used for the genetic transformation were the epicotyls from P. trifoliata. The Agrobacterum tumefaciens strain was EHA101 containing vector plasmid pGA482GG. The coat protein gene (CTV-cp gene), GUS gene and NPT II gene were introduced into the transformation plasmid.

RESULTS

Ceftaxime used as antibiotics was better than carbenicillin. The concentration was 300 mg.L-1; The selection pressure for kanamycin was 50 mg.L-1; 70.0% of the resistant plants were GUS-positive; extra gene was proved to be in P. trifoliata plant by southern blot examination.

CONCLUSION

An effective genetic transformation mediated by Agrobacterium tumefacines, which harbours a CTV-cp gene, has been developed in P. trifoliata. Transgenic CTV-cp plants were obtained.

[Estrogen and progesterone cytosol receptor concentrations in patients with endometriosis and their changes after gossypol therapy]

Estrogen and progesterone cytosol receptor (ERc, PRc) concentrations of endometrium biopsied during different phases of menstrual cycle were measured by dextran-coated charcoal method in 27 normal fertile women and 24 patients with endometriosis. 15 out of 24 endometriotic patients were put on gossypol for 2 months thereafter. After discontinuation of the drug, ERc, PRc contents of endometrium were reexamined during the same cycle day. Serum estradiol (E2) and progesterone (P) levels were also compared before and after gossypol treatment. In addition, endometriotic tissue and intrauterine endometrium were immediately obtained from the same patient after surgery in 16 cases with endometriosis, and their ERc, PRc concentrations were also compared.

RESULTS

endometrium ERc, PRc concentrations of normal controls fluctuated during the menstrual cycle, with the peak at late follicular phase. In endometriosis group, the ERc, PRc contents and cyclic changes of endometrium in situ were not significantly different from the normal controls. However, the ERc, PRc contents of endometriotic tissue were significantly lower than those of endometrium in situ (P = 0.0036 and < 0.0001 respectively) without cyclic changes during menstrual cycle. After 2 months of gossypol therapy, serum E2 and P levels tended to decrease but the differences were not significant. Glandular secretion of endometrium decreased in only 4 out of 15 cases under pathological examination. In contrast, the ERc, PRc concentrations of endometrium in situ differed significantly from the pretreatment values (P = 0.0217 and 0.01 respectively). These data indicated: (1) The response of endometriotic tissue to estrogen and progestin was lower than that of endometrium in situ.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of transmural myocardial infarction by single-photon emission computed tomography with thallium-201: comparison with planar imaging

The ability of single-photon emission computed tomography (SPECT) with thallium-201 to detect transmural myocardial infarction was compared with that of planar imaging. Planar imaging was performed at rest after SPECT in 80 patients with the first myocardial infarction and in 20 patients without myocardial infarction. The planar and SPECT images were interpreted qualitatively. Tomography was significantly more sensitive than planar imaging in detecting inferior infarctions (43/46 or 93% vs 22/46 or 48%; p less than 0.05). In detecting anterior infarctions, the sensitivity rate was 92% (35/38) for SPECT and 79% (30/38) for planar imaging (p = NS). The overall sensitivity was 93% for tomography and 63% for planar imaging (p less than 0.05). The specificity was similar (100%) with the 2 techniques. It is concluded that SPECT significantly improves the detection of thallium-201 myocardial perfusion defects in patients with myocardial infarctions, especially those occurring on the inferior wall.

Electron microscopic observations of the effects of gossypol on the human endometrium

Gossypol treatment of endometriosis and uterine myomas in 15 cases was started with a daily dose of 20 mg of gossypol-acetic acid twice a day for 20 days as a loading dose, followed by 40 mg (20 mg twice weekly). A maintenance dose of 20 mg was given weekly. The total course of treatment lasted about 6 months. Light and electron microscopic examination of the endometrium was carried out before treatment and 2, 3, 4, and 6 months after gossypol treatment. After gossypol treatment three different characteristics of the endometrium were noted: (1) irregular secretory activity, (2) proliferative activity, and (3) atrophy. On electron microscopic examination it was shown that there were important changes of the organelles, indicating suppressed secretory activity. Based on the above results, the nature and significance of the ultrastructural changes of the endometrium induced by gossypol were analyzed and the possibility of developing a new field of research in female contraception with gossypol was considered.