Laparoscopy in ureteral engineering: a feasibility study

Objective

We recently bioengineered a ureter substitute from a seeded scaffold implanted by open surgery in the omentum. In view of the development of laparoscopy in the treatment of benign conditions of the ureter, obtaining a ureter substitute by minimally invasive techniques would be a desirable objective. However, conflicting results about the biological impact of carbon dioxide insufflation on the microcirculation of intra-abdominal organs prompted us to investigate first whether the results obtained by open surgery, in terms of vascular supply and maturation, could be reproduced laparoscopically.

Materials and methods

Bladder full-thickness tissue was harvested laparoscopically from three pigs for urothelial and smooth muscle cell primary cultures subsequently used to seed a small intestinal submucosa (SIS) matrix. After 2 wk, the in vitro seeded constructs were shaped around silicone drains and transferred laparoscopically into the abdomen for omental maturation. Three weeks later, the constructs were harvested for histological, immunohistochemical, and electron microscopic analysis.

Results

The laparoscopic procedures were performed successfully in all animals. After omental maturation, the constructs were vascularized and comprised of a well-differentiated multilayered urothelium with umbrella cells, over connective tissue and smooth muscle cells, with no evidence of fibrosis or inflammation. Electron microscopic analysis showed characteristics of a terminally differentiated urothelium.

Conclusion

As shown by conventional microscopy, immunochemistry, and electron microscopy, carbon dioxide insufflation does not impact cell growth and differentiation. These findings validate the laparoscopic approach for omental maturation of ureter substitutes.     

Preclinical efficacy of ST1976, a novel camptothecin analog of the 7-oxyiminomethyl series

In previous studies, we have documented the potential therapeutic advantages of camptothecin analogs modified at the 7-position, i.e., 7-oxyiminomethyl derivatives. The present study was performed to explore the therapeutic potential of novel hydrophilic derivatives of this series. With one exception (ST1976), the tested camptothecins exhibited a reduced antiproliferative activity and all compounds retained ability to stabilize the topoisomerase I-mediated cleavable complex. The two analogs (ST1976 and ST1968) characterized by the presence of a free amino group in the side chain also exhibited the formation of persistent cleavable complexes. The most potent compound, ST1976 (7-(4-aminobenzyl)oxyiminomethylcamptothecin), was selected for evaluation of its preclinical profile of antitumor activity in a large panel of human tumor xenografts. As expected on the basis of the introduction of a hydrophilic substituent, the novel camptothecin was a substrate for BCRP. However, in spite of an apparent recognition by BCRP, ST1976 was effective following oral administration. The antitumor activity was evaluated using various schedules and routes of administration (i.v. and p.o.). ST1976 exhibited a remarkable activity in all tested tumors and was effective in a number of tumors which are resistant to irinotecan. The biological and pharmacological profile of ST1976 supports the therapeutic potential of camptothecins containing hydrophilic substituents at the 7-position. On the basis of its excellent activity in preclinical models, ST1976 is a promising candidate for clinical development.     

Cohesive, multicomponent, dense powder flow characterization by NIR

Non-aerated powder flows are frequently encountered in downstream pharmaceutical processes. Such flows occur at the entrance of powder compression units, and their characteristics are of great interest because any powder agglomeration or segregation can be detrimental to the quality of the final solid oral dosage form. This work was aimed at developing a process analytical technology (PAT) method, based on near-infrared spectroscopy (NIR) for the in-line powder flow characterization of pharmaceutical formulations. An Ibuprofen drug formulation was selected for study. A bench-scale hopper system was assembled to monitor powder flow behaviour. An in-line commercial NIR Axsun spectrometer and probe were chosen to collect in-line spectral data on dense, multicomponent, non-aerated powder flow prior to compression. Spectra were collected on flowing mannitol and pharmaceutical product blends. A specially designed, non-contact sampling interface allowed the collection of representative process powder flow spectra without affecting blend uniformity. A partial least squares chemometric model was developed for laboratory-prepared samples, to quantitatively determine the flowing powder's active pharmaceutical ingredient (API) level. Static sample spectra and flowing pure mannitol spectra proved to have a high degree of reproducibility. The model's standard error of calibration was 2.95% of the API level with a R2 of 0.991. Flowing blend powder spectra and API estimates showed variations consistent with those seen in model samples. The average values for flowing pharmaceutical blends were close to the API concentration, indicating that the proposed procedure was statistically acceptable. The model is considered very promising, and some improvements would lead to its final acceptance at production scale as a PAT tool.     

Pharmacokinetic considerations for antimicrobial therapy in patients receiving renal replacement therapy

Continuous renal replacement therapy (CRRT), particularly continuous venovenous haemofiltration (CVVH) and continuous venovenous haemodiafiltration (CVVHDF), are gaining increasing relevance in routine clinical management of intensive care unit patients. The application of CRRT, by leading to extracorporeal clearance (CL(CRRT)), may significantly alter the pharmacokinetic behaviour of some drugs. This may be of particular interest in critically ill patients presenting with life-threatening infections, since the risk of underdosing with antimicrobial agents during this procedure may lead to both therapeutic failure and the spread of breakthrough resistance. The intent of this review is to discuss the pharmacokinetic principles of CL(CRRT) of antimicrobial agents during the application of CVVH and CVVHDF and to summarise the most recent findings on this topic (from 1996 to December 2006) in order to understand the basis for optimal dosage adjustments of different antimicrobial agents. Removal of solutes from the blood through semi-permeable membranes during RRT may occur by means of two different physicochemical processes, namely, diffusion or convection. Whereas intermittent haemodialysis (IHD) is essentially a diffusive technique and CVVH is a convective technique, CVVHDF is a combination of both. As a general rule, the efficiency of drug removal by the different techniques is expected to be CVVHDF > CVVH > IHD, but indeed CL(CRRT) may vary greatly depending mainly on the peculiar physicochemical properties of each single compound and the CRRT device's characteristics and operating conditions. Considering that RRT substitutes for renal function in clearing plasma, CL(CRRT) is expected to be clinically relevant for drugs with dominant renal clearance, especially when presenting a limited volume of distribution and poor plasma protein binding. Consistently, CL(CRRT) should be clinically relevant particularly for most hydrophilic antimicrobial agents (e.g. beta-lactams, aminoglycosides, glycopeptides), whereas it should assume much lower relevance for lipophilic compounds (e.g. fluoroquinolones, oxazolidinones), which generally are nonrenally cleared. However, there are some notable exceptions: ceftriaxone and oxacillin, although hydrophilics, are characterised by primary biliary elimination; levofloxacin and ciprofloxacin, although lipophilics, are renally cleared. As far as CRRT characteristics are concerned, the extent of drug removal is expected to be directly proportional to the device's surface area and to be dependent on the mode of replacement fluid administration (predilution or postdilution) and on the ultrafiltration and/or dialysate flow rates applied.Conversely, drug removal by means of CVVH or CVVHDF is unaffected by the drug size, considering that almost all antimicrobial agents have molecular weights significantly lower (<2000Da) than the haemofilter cut-off (30,000-50,000Da). Drugs that normally have high renal clearance and that exhibit high CL(CRRT) during CVVH or CVVHDF may need a significant dosage increase in comparison with renal failure or even IHD. Conversely, drugs that are normally nonrenally cleared and that exhibit very low CL(CRRT) during CVVH or CVVHDF may need no dosage modification in comparison with normal renal function. Bearing these principles in mind will almost certainly aid the management of antimicrobial therapy in critically ill patients undergoing CRRT, thus containing the risk of inappropriate exposure. However, some peculiar pathophysiological conditions occurring in critical illness may significantly contribute to further alteration of the pharmacokinetics of antimicrobial agents during CRRT (i.e. hypoalbuminaemia, expansion of extracellular fluids or presence of residual renal function). Accordingly, therapeutic drug monitoring should be considered a very helpful tool for optimising drug exposure during CRRT.     

Nocebo hyperalgesia: how anxiety is turned into pain

PURPOSE OF REVIEW: Nocebo hyperalgesia is a phenomenon that is opposite to placebo analgesia and whereby expectation of pain increase plays a crucial role. In recent times, both the neuroanatomical and the neurochemical bases of the nocebo effect and of nocebo-related effects have begun to be explored. Here, we highlight recent advances in our understanding of the neurobiology of the nocebo hyperalgesic effect. RECENT FINDINGS: A typical nocebo hyperalgesic response occurs following the administration of an inert substance which the subject believes to be a hyperalgesic agent (negative placebo or nocebo). It has been shown that the subject's negative expectations of pain worsening induce anticipatory anxiety about the impending pain increase and this triggers the activation of cholecystokinin that, in turn, facilitates pain transmission. Accordingly, cholecystokinin antagonists have been found to prevent this anxiety-induced hyperalgesia. Brain-imaging studies have shown that the perceived intensity of a painful stimulus following negative expectations of pain increase is higher than in the absence of negative expectations and this is associated with changes in activation of specific brain regions. SUMMARY: Since pain appears to be amplified by anxiety through the activation of cholecystokininergic systems, new therapeutic strategies, such as new cholecystokinin antagonists, can be envisaged whenever pain has an important anxiety component.     

Fatal ongoing human cytomegalovirus reactivation during high‐dose melphalan and autologous stem cell transplantation

Human cytomegalovirus (HCMV) reactivation can cause a wide range of complications in hematopoietic stem cell transplant recipients, ranging from pneumonia to graft failure. Although reactivations are usually seen in the early post‐transplant period, ongoing and untreated HCMV reactivation at the time of high‐dose chemotherapy and autologous stem cell support is an exceedingly rare circumstance whose consequences remain largely unknown. This case report describes a patient who underwent high‐dose melphalan and autologous transplantation with unknown active HCMV replication. J. Med. Virol. 81:857–860, 2009. © 2009 Wiley‐Liss, Inc.     

Caveolins and flotillin-2 are present in the blood stages of Plasmodium vivax

Blood stages of Plasmodium vivax induce the development of caveolae and caveola–vesicle complexes (CVC) in the membrane of their host erythrocyte. Caveolae are found in almost all types of cells and are involved in endogenous processes as calcium and cholesterol homeostasis, cell signalling, transporting, ligand internalization and transcytosis of serum components. Major structural components of caveolae are the proteins caveolins and flotillins. The functional role of caveolae in the P. vivax-infected erythrocyte is not properly understood. As these organelles have been shown to contain malaria antigens, it has been suggested that they are involved in the transport and release of specific parasite antigens from the infected erythrocyte and in the uptake of plasma proteins. Using specific antibodies to classical caveolae proteins and an immunolocalization approach, we found caveolin-2, caveolin-3, and flotillin-2 in the vesicle profiles and some CVC of P. vivax-infected erythrocytes. Caveolin-1–3 were not found in uninfected erythrocytes. This is the first report of identification and localization of caveolins in the CVC present in erythrocytes infected with P. vivax, thereby providing evidence of the role of this particular organelle in the protein-trafficking pathway that connect parasite-encoded proteins with the erythrocyte cytoplasm and the cell surface throughout the asexual blood cycle of vivax malaria parasite.     

Sleep-disordered breathing in fatigued postpoliomyelitis clinic patients

OBJECTIVE: To determine the frequency, predictive factors, and symptoms predictive of sleep-disordered breathing (SDB) in fatigued postpoliomyelitis clinic patients. DESIGN: Cross-sectional, retrospective chart review. SETTING: University-affiliated hospital postpolio clinic. PARTICIPANTS: Postpolio clinic charts (N=590) were reviewed. Ninety-eight patients were included, and 492 patients were not included, primarily because of the lack of a polysomnogram. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The Apnea-Hypopnea Index (AHI) calculated as the total number of sleep-related breathing events/total sleep time. RESULTS: The frequency of SDB defined by an AHI score of 5 or more was 65% and by an AHI score of 10 or more was 50%. Obstructive hypopnea was the predominant form, occurring in 86%. Age, sex, age at acute polio, time since polio, weakness and respiratory difficulties at acute polio, bulbar involvement at acute polio and at evaluation, body mass index, pulmonary function measures, alcohol use, sedative drug use, smoking, fibromyalgia, kyphoscoliosis, and scoliosis and ear-nose-throat surgery were not predictive of SDB (AHI scores > or =5 and > or =10). Snoring was more common in subjects with SDB (AHI score > or =5 and > or =10). Some pulmonary function measures correlated with oxygen saturation during sleep in SDB (AHI scores > or =5). CONCLUSIONS: SDB was very common in fatigued postpoliomyelitis clinic patients referred for sleep evaluation. Obstructive hypopnea was the most frequent type. In this preliminary study, snoring tended to predict SDB.     

High maternal blood S100B concentrations in pregnancies complicated by intrauterine growth restriction and intraventricular hemorrhage

BACKGROUND: Intrauterine growth restriction (IUGR) is associated with perinatal mortality and with neurologic damage from intraventricular hemorrhage (IVH). We investigated whether S100B, a neural protein found in high concentrations after cell injury in the nervous system, is increased in serum of women whose pregnancies are complicated by IUGR and whose newborns develop IVH. We also explored the prognostic accuracy of maternal serum S100B for IVH in the newborn. METHODS: We conducted a case-control study of 106 pregnancies complicated by IUGR, including a subgroup (n = 26) who developed IVH after birth, and 212 unaffected pregnancies matched for gestational age. Ultrasound examination, Doppler velocimetry patterns (in the utero-placental vessels and middle cerebral artery), and maternal blood collection were performed before birth; cerebral ultrasound and neurologic examinations were performed after birth. RESULTS: S100B was higher (P <0.001) in IUGR pregnancies complicated by IVH than in those that were not and in controls. At a cutoff of 0.72 microg/L, sensitivity was 100% [95% confidence interval (95% CI), 87%-100%] and specificity was 99.3% (97.5%-99.9%) for prediction of IVH (area under the ROC curve, 0.999). The prevalence of IVH was 8.2% in the whole study population, 93% (95% CI, 83.6%-100%) in those with maternal S100B >0.72 microg/L, and 0% (0%-2.5%) in those with maternal S100B <0.72 microg/L. CONCLUSION: For prediction of IVH, measurements of maternal S100B may be useful at times before clinical, laboratory, and ultrasound patterns can identify risk of IVH.