Release of naltrexone on buccal mucosa: permeation studies, histological aspects and matrix system design.

Transbuccal drug delivery has got several well-known advantages especially with respect to peroral way. Since a major limitation in buccal drug delivery could be the low permeability of the epithelium, the aptitude of NLX to penetrate the mucosal barrier was assessed. Ex vivo permeation across porcine buccal mucosa 800 microm thick was investigated using Franz type diffusion cells and compared with in vitro data previously obtained by reconstituted human oral epithelium 100 microm thick. Both fluxes (Js) and permeability coefficients (K(p)) are in accordance, using either buffer solution simulating saliva or natural human saliva. Permeation was evaluated also in presence of chemical enhancers or iontophoresis. No significant differences in penetration rate were observed using chemical enhancers; in contrast, Js and K(p) were extensively affected by application of electric fields. Tablets, designed for Naltrexone hydrochloride (NLX) administration on buccal mucosa, were developed and prepared by direct compression of drug loaded (56%) poly-octylcyanocrylate (poly-OCA) matrices. NLX is slowly discharged from buccal tablets following Higuchian kinetic. Histologically, no signs of flogosis ascribable to NLX and/or poly-OCA were observed, while cytoarchitectural changes due to iontophoresis were detected. Buccal tablets containing NLX may represent a potential alternative dosage form in addiction management.     

Gap junction synthesis and degradation as therapeutic targets

The synthesis and the degradation of gap junctions involve multiple steps that may provide targets for the modulation of intercellular communication. Many studies using cultured cells have examined the effects of inhibitors of protein synthesis, trafficking, or degradation upon connexins. Similarly, activators or inhibitors of various protein kinases have been shown to affect connexin assembly or proteolysis. These studies have helped to elucidate the connexin life-cycle. But, because of their lack of specificity for gap junction proteins, these agents would be expected to have limited therapeutic utility and to produce several deleterious side effects. However, more selective agents are being developed based on specific features of the connexin sequences. Molecular genetic approaches have been used to introduce wild-type connexins to increase intercellular communication in otherwise poorly coupled cells. Decreased intercellular communication may be obtained by application of peptides that mimic the extracellular loops and may prevent docking of hemi-channels. Alternatively, introducing mutant connexins that interfere with the oligomerization/export of endogenous connexins or with channel function by formation of non-functional heteromeric hemi-channels can also reduce intercellular communication.     

Surgical technique of intraoperative radiotherapy in conservative treatment of limited-stage breast cancer

At the European Institute of Oncology, Milan, Italy, we have focused our interest on the use of intraoperative radiation therapy (IORT) in limited-stage breast cancer that is conservatively treated. A new technique to perform IORT was applied in 185 patients from July 1, 1999, to October 31, 2001. As the surgeon plays a crucial role in this procedure in selecting the patients, performing the breast resection, preparing the gland as a target to receive IORT, delivering the radiation directly to the mammary gland via a dedicated applicator, and, finally, reconstructing the breast, each phase of the surgical technique has been completely standardized and is described herein. The use of IORT in the conservative treatment of breast cancer could allow the course of external fractionated-dose radiation therapy to be completely avoided; IORT dramatically reduces radiation exposure of the skin, lung, and subcutaneous tissues and avoids the irradiation of the contralateral breast, which contributes to a very low incidence of radiation-induced sequelae. In our experience, IORT for limited-stage breast carcinoma is easy to perform and only briefly prolongs the duration of the surgical procedure.     

Effect of iomeprol on rat hippocampal slice synaptic transmission: comparison with other X-ray contrast agents

RATIONALE AND OBJECTIVES: All contrast agents should be neurologically safe because although some are not indicated for procedures, such as myelography, just the same they may come in contact with nervous tissue during contrast-enhanced imaging. This is because even when they are intravascularly injected, the presence of undiagnosed blood-brain barrier damage may allow them to penetrate the brain barrier. In the present study, we investigated the neurologic safety of iomeprol by studying in vitro its potential effects on the central nervous system (CNS) synaptic transmission. Other widely used x-ray contrast agents were also assessed for comparative purposes. METHODS: CNS synaptic transmission was evaluated in terms of evoked field potentials recorded from the pyramidal region of rat hippocampal slices. The field potentials were evoked by electrical stimulation of the Schaffer collateral pathway. The effects of the contrast agents were evaluated in terms of number and amplitude of population spikes (PS) and as the maximal slope of the excitatory postsynaptic potentials (EPSP). The contrast agents were tested at final concentrations of 3, 10, and 30 mg(iodine)/mL in iso-osmolal condition with respect to artificial cerebrospinal fluid (CSF). RESULTS: Iomeprol, like ioversol, principally exerted a mild inhibitory effect on CNS synaptic transmission, an effect that was preceded by a weak, transient excitation. Iopentol exerted a rapid and complete inhibition of synaptic transmission without showing any excitatory effects. Iobitridol, though belonging to the nonionic monomeric class, exerted, surprisingly, an epileptogenic action at the highest concentration, whereas its inhibitory action was slow and mild. Diatrizoate, as expected, exerted an epileptogenic activity even at the lowest concentration, followed by a marked inhibitory action. Ioxaglate, as expected because it is an ionic though dimeric contrast agent, exerted an epileptogenic action at the intermediate concentration, whereas it barely demonstrated an inhibitory effect at all. All the contrast agent effects observed in the study reversed or tended to reverse during washout. CONCLUSIONS: Even taking in account the limitation because of the use of an in vitro approach and high contrast agent concentrations, we can conclude that the positive neuro-tolerability of iomeprol is further confirmed by this model as it proved to be devoid of epileptogenic activity and, among the contrast agents exhibiting inhibitory action, it was the contrast agent with the least amount of activity. In addition, contrary to that generally reported in the literature, nonionic, low osmolal contrast agents are not all identical in their neuro-tolerability when assessed in the rat hippocampal slice model.     

Differential production of angiostatin by concomitant antitumoral resistance-inducing cancer cells

HCC is a common cancer and HBV and AFB(1) are well-documented, major risk factors. Epidemiologic studies have documented that cigarette smoking also contributes to the development of HCC. PAHs are ubiquitous environmental pollutants and products of incomplete combustion. They are present in both mainstream and sidestream cigarette smoke. PAHs are metabolically activated by phase I enzymes, including CYP1A1, into electrophilic reactants (diol epoxides), which covalently bind to DNA to form adducts. Diol epoxides are also substrates for phase II detoxifying enzymes, including GSTM and GSTP. To examine the association between PAH-DNA adducts and HCC, adduct levels were determined in liver tissue by relative staining intensity with an immunoperoxidase method using a polyclonal antiserum against BPDE-modified DNA. Subjects were also genotyped for polymorphism in several genes involved in the metabolism of PAH, including GSTM1 and GSTP1. Liver tissue was collected from patients with histologically confirmed HCC (n = 105) and from non-HCC controls (n = 37). There was a significant positive correlation (r = 0.3, p < 0.01) between adducts in tumor and adjacent nontumor tissues among HCC cases. The risk of HCC was higher after adjustment for age, sex and HBsAg in the group with the highest tertile tissue levels of PAH-DNA adducts (mean relative nuclear staining intensity of tumor and nontumor tissue > 344) than in the group with the lowest tertile (staining < 241, OR = 3.9, 95% CI = 1.0-14.9). Among non-HCC controls, there were no significant associations between adduct levels and cigarette smoking, GSTM1 null genotype and HBsAg positivity. A strikingly increased HCC risk was observed (OR = 20.3, 95% CI = 5.0-81.8) among HBsAg-positive subjects whose PAH-DNA adduct levels were high (mean relative nuclear staining intensity of tumor and nontumor tissue > 301, median of control tissues) compared to HBsAg-negative subjects who had low PAH-DNA adduct levels. 4-ABP- and AFB(1)-DNA adducts had been measured previously in these same tissues. Subjects with elevated DNA adduct levels of PAH, 4-ABP and AFB(1) had a significantly higher HCC risk with an OR of 36.7 (95% CI 7.2-187.2) compared to those who had low DNA adduct levels. These results suggest that PAHs may play a role in human hepatocarcinogenesis in conjunction with HBsAg carrier status, GSTM1 and GSTP1 genotypes and exposure to 4-ABP and AFB(1).     

Axillary radiotherapy instead of axillary dissection: A randomized trial

Background Surgical dissection of the axilla is a standard part of the treatment of breast cancer but, by itself, does not improve prognosis; furthermore, most patients with small-sized breast cancer and a clinically uninvolved axilla never develop axillary metastases. We evaluated disease-free and overall survival in patients with early breast cancer treated by breast-conservation surgery without dissection of acillary lymph nodes, receiving or not receiving axillary radiotherapy (RT). Methods From 1995 to 1998, 435 patients older than 45 years with breast cancer up to 1.2 cm were randomized, 214 to breast conservation without axillary treatment and 221 to breast conservation plus axillary RT. Results After a follow-up of 28 to 68 months (median, 42 months), two women (1%) in the no axillary treatment group and one (.5%) in the axillary RT group developed axillary metastases. Rates of distant metastases and local treatment failure were also very low, and 5-year overall survival was 99%. Conclusions After a mean of 46 months of follow-up, our results indicate that axillary dissection can be safely avoided in patients with very small invasive carcinomas and a clinically negative axilla. Whether axillary RT should be added can be assessed only by longer follow-up. Presented at the 54th Annual Meeting of the Society of Surgical Oncology, Washington, DC, March 15–18, 2001.     

Real-time in vivo dosimetry using micro-MOSFET detectors during intraoperative electron beam radiation therapy in early-stage breast cancer.

PURPOSE: In a previous paper we reported the results of off-line in vivo measurements using radiochromic films in IOERT. In the present study, a further step was made, aiming at the improvement of the effectiveness of in vivo dosimetry, based on a real-time check of the dose. MATERIALS AND METHODS: Entrance dose was determined using micro-MOSFET detectors placed inside a thin, sterile, transparent catheter. The epoxy side of the detector was faced towards the beam to minimize the anisotropy. Each detector was plugged into a bias supply (standard sensitivity) and calibrated at 5 Gy using 6 MeV electrons produced by a conventional linac. Detectors were characterized in terms of linearity, precision and dose per pulse dependence. No energy and temperature dependence was found. The sensitivity change of detectors was about 1% per 20 Gy accumulated dose. Correction factors to convert surface to entrance dose were determined for each combination of energy and applicator. From November 2004 to May 2005, in vivo dosimetry was performed on 45 patients affected by early-stage breast cancer, who underwent IOERT to the tumour bed. IOERT was delivered using electrons (4-10 MeV) at high dose per pulse, produced by either a Novac7 or a Liac mobile linac. RESULTS: The mean ratio between measured and expected dose was 1.006+/-0.035 (1 SD), in the range 0.92-1.1. The procedure uncertainty was 3.6%. Micro-MOSFETs appeared suitable for in vivo dosimetry in IOERT, although some unfavourable aspects, like the limited lifetime and the anisotropy with no build-up, were found. Prospectively, a real-time action level (+/-6%) on dose discrepancy was defined. CONCLUSIONS: Excellent agreement between measured and expected doses was found. Real-time in vivo dosimetry appeared feasible, reliable and more effective than the method previously published.     

Sentinel Node Biopsy Interpretation: The Milan Experience

From March 1996 to December 1999 we performed 1,266 sentinel node biopsies (SNBs) in patients with small breast cancers. The technique is to inject technetium 99m-labeled albumin particles close to the tumor, locate the sentinel node (SN) scintigraphically, and use a handheld gamma-detecting probe to guide its removal via a small incision during breast surgery. Our experience was divided into three phases. In the first phase, complete axillary dissection was performed to assess the accuracy of SNB in predicting axillary status. We also assessed safety, perfected tracer injection technique, determined optimal particle size and radioactivity levels, optimized lymphoscintigraphic scanning, and perfected the surgical technique. The SN was identified and removed in 98.7% of cases. Comparison with complete axillary dissection showed that the SN predicted axillary status in 96.8% of cases. However, use of an intraoperative frozen section method predicted axillary status in only 86.5% of cases. In the second phase we developed a new method for intraoperative histologic analysis. Extensive sampling (up to 60 sections/SN) and an experienced pathologist proved more important than use of antikeratin immunostaining in identifying tumor cells, and the new method has the accuracy of a definitive histologic examination. The third phase, a randomized trial, closed at the end of 1999. Trial objectives were to confirm that the SN predicts axillary status, to determine the number of axillary relapses, and to assess overall and disease-free survival. Patients were randomized in the operating room to complete axillary dissection or SNB. If the SN was positive, complete axillary dissection was performed; if the SN was negative, no further axillary treatment was given. We expect the trial to confirm our clinical experience that SNB is a safe and accurate procedure for staging patients with early breast cancer and a clinically negative axilla.