Preclinical and clinical studies of NK012, an SN-38-incorporating polymeric micelles, which is designed based on EPR effect.

Polymeric micelles are ideally suited to exploit the EPR effect, and they have been used for the delivery of a range of anticancer drugs in preclinical and clinical studies. NK012 is an SN-38-loaded polymeric micelle constructed in an aqueous milieu by the self-assembly of an amphiphilic block copolymer, PEG-PGlu(SN-38). The antitumor activity was evaluated in several orthotopic tumor models including glioma, renal cancer, stomach cancer, and pancreatic cancer. Two independent phase I clinical trials were conducted in Japan and the USA. In the preclinical studies, it was demonstrated that NK012 exerted significantly more potent antitumor activity with no intestinal toxicity against various orthotopic human tumor xenografts than CPT-11. In clinical trials, predominant toxicity was neutropenia. Non-hematologic toxicity, especially diarrhea, was mostly Grade 1 or 2 during study treatments. Total 8 partial responses were obtained. According to data of preclinical studies, NK012 showing enhanced distribution with prolonged SN-38 release may be ideal for cancer treatment because the antitumor activity of SN-38 is time dependent. Clinical studies showed that NK012 was well tolerated and had antitumor activity including partial responses and several occurrences of prolonged stable disease across a variety of advanced refractory cancers. Phase II studies are ongoing in patients with colorectal cancer in Japan and in patients with triple negative breast cancer and small cell lung cancer in the USA.

A substance P receptor (NK1) antagonist enhances the widespread osteoporotic effects of sciatic nerve section.

The long-term effects of sciatic nerve section on bone mineral density (BMD) were studied using dual-energy X-ray absorptiometry (DEXA) in skeletally mature rats. Unilateral sciatic neurectomy caused the rapid loss of cancellous bone in the proximal and distal femur and tibia in the ipsilateral hindlimb and, to a lesser extent, in the contralateral intact hindlimb. The reduction in BMD rapidly progressed for 4 weeks after sciatic section and then gradually stabilized with no evidence of recovery at 12 weeks. The development of osteoporosis in the contralateral intact hindlimb was a novel finding. There was no evidence of disuse in the normal contralateral hindlimb after unilateral sciatic section; grid-crossing activity over a 24-h interval was unchanged and there was no reduction in weight bearing on the contralateral normal hindpaw during the stance phase of ambulation. Unilateral peripheral nerve lesions have well-documented effects on substance P content and function in the corresponding contralateral intact nerve. We hypothesized that after sciatic section a reduction in substance P signaling might contribute to bone loss in the contralateral hindlimb. Daily administration of the substance P receptor (NK1) antagonist LY303870 for 2 weeks caused significant loss of cancellous bone in the denervated and the contralateral hindlimb, evidence that substance P signaling sustained bone density after nerve section. After sciatic neurectomy there was a 33% reduction in sciatic nerve stimulation-evoked extravasation in the contralateral intact hindlimb, indicating transmedian inhibition of substance P signaling after nerve injury. Furthermore, there was a 50% reduction in the substance P content in both tibias after unilateral sciatic section. Collectively, these data support the hypothesis that a widespread reduction in substance P content in bone contributes to the osteoporotic effects of sciatic neurectomy and that residual substance P signaling maintains bone integrity after nerve section in both the denervated and contralateral intact hindlimb.

Transurethral vaporisation of the prostate and irrigating fluid absorption.

Transurethral vaporisation of the prostate gland (TUVP) is an emerging surgical alternative to conventional electroresection (TURP). This study examined vesical pressure and fluid absorption during TUVP in 35 patients with benign prostatic hypertrophy. The irrigating fluid was a solution of glycine 1.5% and ethanol 1%. Intraoperative intravesical pressure was monitored continuously and absorption of irrigating fluid was detected by ethanol analysis in expired breath. The incidence of absorption during TUVP was 34%. Intravesical pressures were higher amongst patients who went on to absorb than amongst patients who did not. Combining data from the current study and from 35 patients in our previous investigation into TURP (Gray et al.: Anaesthesia 2001; 56: 461-4), urological trainees operated at higher mean pressure and for longer than their consultant colleagues and their resections were significantly more likely to result in absorption. The incidence of irrigating fluid absorption during trainees' operations appeared to be less using TUVP than using conventional TURP.

Influence of antioxidants on the blood-brain barrier permeability during epileptic seizures.

Pentylenetetrazol-induced seizures in rats lead to the breakdown of the blood-brain barrier. We compared the disruption of the blood-brain barrier during epileptic seizure in untreated rats and in rats treated with vitamin E or selenium. The rats were supplemented with nontoxic doses of sodium selenite (4 pp) in drinking water for 3 months, or vitamin E (70 mg/kg) was given intraperitoneally for 30 min before the pentylenetetrazole injection. Evans-blue was used as a blood-brain barrier tracer and was given intravenously at a dose of 4 ml/kg of a 2% solution. The rats were divided into four experimental groups. Group I: control (n = 24); Group II: pentylenetetrazole-induced seizure (n = 12); Group III: vitamin E injected + seizure (n = 12); Group IV: Selenium supplemented + seizure (n = 12). The rats subjected to epileptic seizures showed Evans-blue albumin extravasations especially in the thalamic nuclei, brainstem, occipital, and frontal cortex. Mean values for Evans-blue dye were found to be 0.28 +/- 0.04 mg % brain tissue in control rats and 1.6 +/- 0.2 mg % brain tissue after epileptic seizures (P < 0.01). The magnitude of distribution of the blood-brain barrier during epileptic seizures was significantly less in rats treated with vitamin E or selenium. The mean value for Evans-blue dye was found to be 1.2 +/- 0.1 mg % brain tissue in selenium supplemented rats and 1.2 +/- 0.1 mg % brain tissue in vitamin E injected rats after epileptic seizures. This difference between treated and untreated animals was found to be significant (P < 0.05). The findings of the present study suggest that free radicals contribute to disruption of the blood-brain barrier during pentylenetetrazol-induced seizures.

The X-ray contrast medium iodixanol detects increased colonic permeability equally well as 51Cr-labeled ethylenediaminetetraacetic acid in experimental colitis of rats.

BACKGROUND: Non-ionic, water-soluble radiographic contrast media have been suggested as intestinal permeability probes. We studied the permeability of the isosmolar contrast medium iodixanol and 51Cr-labeled ethylenediaminetetraacetic acid (EDTA) from the non-perforated colon after induction of colonic inflammation. METHODS: Colonic inflammation and ulcerations were induced by luminal colonic instillation of trinitrobenzenesulfonic acid, dissolved in 40% ethanol. Controls received saline. Fourteen days later iodixanol, 320 mg I/ml, and 51Cr-EDTA were given as an enema. Urine was collected for the subsequent 6 h and subjected to high-performance liquid chromatography and gamma activity counting. RESULTS: Urinary recovery of iodixanol and 51Cr-EDTA increased gradually with severity of the colonic inflammation. The correlation between iodixanol and 51Cr-EDTA recovery was strong (corr.coeff = 0.97). CONCLUSIONS: Iodixanol shows as good properties as 51Cr-EDTA when used as intestinal permeability probe in the inflamed and ulcerated rat colon. Use of the radiopaque properties of iodixanol enable intestinal probe exposure registration by film or fluoroscopy.

Long term exposure to heat reduces edema formation after closed head injury in the rat.

Cerebral edema is one of the major consequences of head trauma (HT); its evolution may cause secondary ischemia and neuronal damage. In a closed head injury model in rats, we have shown BBB disruption and edema formation during the post traumatic period. We have previously shown that chronic exposure to moderate heat improves clinical outcome of rats subjected to HT. Long term exposure to heat results in the achievement of a stable acclimated state, characterized by a lower metabolic rate and improved heat tolerance. In the present study, we investigated the effect of chronic exposure to heat on edema formation after HT. Rats were held at 24 degrees C (CON) or 34 degrees C (ACC) for one month. Injury was then induced under ether anesthesia by a weight drop device. Four or 48 hours later, they were sacrificed for evaluation of BBB integrity (Evans blue, EB, extravasation) or edema formation (specific gravity, SG, or percent water). We found that EB uptake by the contused hemisphere was 6 fold lower in the ACC rats as compared to CON (p < 0.001). Furthermore, edema measured at 48 h by both SG and percent water methods was significantly lower in the acclimated rats (p < 0.01). We suggest that heat acclimation offers protection to rats subjected to head injury, possibly by reduction of plasma proteins extravasation.

Effect of antiasthma drugs on microvascular leakage in guinea pig airways.

We have studied the effect of intravenous epinephrine, albuterol, verapamil, and aminophylline on airway microvascular leakage in guinea pigs. Microvascular leakage was induced by platelet-activating factor (PAF; 50 ng/kg intravenously), which acts directly on venular endothelial cells, and measured by quantifying extravasation of Evans blue (EB) dye. Epinephrine (20 micrograms/kg) inhibited PAF-induced changes in dye leakage in larynx and main bronchi; at 80 and 160 micrograms/kg, significant inhibition was observed in all airways studied. This effect was reversed by phentolamine (2.5 mg/kg) or prazosin (100 micrograms/kg). By contrast, albuterol (20 to 320 micrograms/kg) and aminophylline (12.5 to 50 mg/kg) failed to inhibit dye leakage at any dose studied. Verapamil inhibited PAF-increased leakage in larynx, main bronchi, and intrapulmonary airways at the lowest dose tested (125 micrograms/kg), although inhibition was not dose dependent. These results suggest that the antiedema effect of epinephrine may be due to vasoconstriction rather than to a direct effect on endothelial cell contractility and that neither beta-agonists nor theophylline have an inhibitory effect. The inhibitory effect of epinephrine on airway microvascular leakage may have therapeutic implications for asthma.