Vitamin A microencapsulation within poly(methyl methacrylate)‐g‐polyethylenimine microspheres: Localized proton buffering effect on vitamin A stability

To stabilize vitamin A in a cosmetic/dermatological formulation, we present here a new encapsulation method based on polymer microspheres having a localized “proton‐buffering” capacity. Poly(methyl methacrylate)‐g‐polyethylenimine (PMMA‐g‐PEI) was prepared by direct condensation grafting of PEI onto poly(methyl methacrylate‐co‐methyl acrylic acid). The reaction was confirmed by FT‐IR analysis showing the amide vibration at 1,550 cm^?1. Elemental analysis indicated that the weight content of the grafted PEI was 1.6% (w/w). Vitamin A was encapsulated into PMMA‐g‐PEI microspheres by using an oil‐in‐water (O/W) single emulsion method. The presence of PEI moiety dramatically improved the chemical stability of vitamin A in microspheres. Vitamin A encapsulated within PMMA‐g‐PEI microspheres maintained 91% of its initial activity after 30‐day incubation at 40°C, while only maintaining 60% within plain PMMA microspheres. This study demonstrates that proton‐buffering within hydrophobic polymer matrix is a useful strategy for stabilizing “acid‐labile” active ingredients. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 517–522, 2004     

Biliary tract complications in laparoscopic cholecystectomy. A multicenter study of 148 biliary tract injuries in 26,440 operations

BACKGROUND: Several ecologic analyses have shown significant positive associations between mean indoor radon concentrations and risk of leukemia at all ages (acute myeloid leukemia and chronic lymphocytic leukemia) and for children (all leukemia, acute myeloid leukemia, and acute lymphoblastic leukemia [ALL]). As part of an age-matched, case-control study of childhood ALL in the United States, we investigated the association between the incidence of ALL in children under age 15 years and indoor radon exposure. METHODS: Radon detectors were placed in current and previous homes of subjects where they resided for 6 months or longer. Children were included in analyses if radon measurements covered 70% or more of the 5-year period prior to diagnosis for case subjects (or from birth for case subjects under age 5 years) and the corresponding reference dates for control subjects. Radon levels could be estimated for 97% of the exposure period for the eligible 505 case subjects and 443 control subjects. RESULTS: Mean radon concentration was lower for case subjects (65.4 becquerels per cubic meter [Bqm(-3)]) than for control subjects (79.1 Bqm(-3)). For categories less than 37, 37-73, 74-147, and 148 or more Bqm(-3) of radon exposure, relative risks based on matched case-control pairs were 1.00, 1.22, 0.82, and 1.02, respectively, and were similar to results from an unmatched analysis. There was no association between ALL and radon exposure within subgroups defined by categories of age, income, birth order, birth weight, sex, type of residence, magnetic field exposure, parental age at the subject's birth, parental occupation, or parental smoking habits. CONCLUSIONS: In contrast to prior ecologic studies, the results from this analytic study provide no evidence for an association between indoor radon exposure and childhood ALL.     

The effect of lesser curve seromyotomy of the stomach in animal experiments

The authors investigated the efficiency of the seromyotomy of the lesser curvature of the stomach in 11 dogs. Reduction of the acid production was verified by glass electrode pH measuring of the gastric mucosa. Scintigraphic examination showed that the operation did not damage the motor function (motility) of the stomach. The fact of peripheral vagotomy was established by histological examination: degeneration of nerve fibres was detected on the peripheral side of the line of the seromyotomy, vacuolar degeneration was found in the cells of parasympathetic ganglions, and amputation neurinomas were shown in the line of the seromyotomy.     

Additional Lithium Storage on Dynamic Electrode Surface by Charge Redistribution in Inactive Ru Metal

Beyond a traditional view that metal nanoparticles formed upon electrochemical reaction are inactive against lithium, recently their electrochemical participations are manifested and elucidated as catalytic and interfacial effects. Here, ruthenium metal composed of ≈5 nm nanoparticles is prepared and the pure ruthenium as a lithium‐ion battery anode for complete understanding on anomalous lithium storage reaction mechanism is designed. In particular, the pure metal electrode is intended for eliminating the electrochemical reaction‐derived Li₂O phase accompanied by catalytic Li₂O decomposition and the interfacial lithium storage at Ru/Li₂O phase boundary, and thereby focusing on the ruthenium itself in exploring its electrochemical reactivity. Intriguingly, unusual lithium storage not involving redox reactions with electron transfer but leading to lattice expansion is identified in the ruthenium electrode. Size‐dependent charge redistribution at surface enables additional lithium adsorption to occur on the inactive but more environmentally sensitive nanoparticles, providing innovative insight into dynamic electrode environments in rechargeable lithium chemistry.     

Anti‐Atherogenic Effect of Stem Cell Nanovesicles Targeting Disturbed Flow Sites

Atherosclerosis development leads to irreversible cascades, highlighting the unmet need for improved methods of early diagnosis and prevention. Disturbed flow formation is one of the earliest atherogenic events, resulting in increased endothelial permeability and subsequent monocyte recruitment. Here, a mesenchymal stem cell (MSC)‐derived nanovesicle (NV) that can target disturbed flow sites with the peptide GSPREYTSYMPH (PREY) (PMSC‐NVs) is presented which is selected through phage display screening of a hundred million peptides. The PMSC‐NVs are effectively produced from human MSCs (hMSCs) using plasmid DNA designed to functionalize the cell membrane with PREY. The potent anti‐inflammatory and pro‐endothelial recovery effects are confirmed, similar to those of hMSCs, employing mouse and porcine partial carotid artery ligation models as well as a microfluidic disturbed flow model with human carotid artery‐derived endothelial cells. This nanoscale platform is expected to contribute to the development of new theragnostic strategies for preventing the progression of atherosclerosis.     

Attenuation coefficient of a piezoelectric resonator operating in a thickness mode

We have found a simple method which gives the attenuation coefficient in the transmission-line model for a piezoelectric resonator operating in a thickness mode. This attenuation coefficient has been determined in terms of the thickness, static capacitance, piezoelectric coupling constant, resonance frequency and the additional value of the maximum input resistance.     

Performance analysis of piezoelectric composite plates with consideration of the internal losses

The performance of a 2.3 MHz composite transducer with 1-3 connectivity is analyzed using the transmission line model. The basic transducer parameters, including the attenuation coefficient, are determined from the electrical impedance in the vicinity of the resonance. Using these parameters, the effects of internal losses on round trip insertion loss (RTIL) are investigated. Also, electrical impedance, pulse-echo, and RTIL response are calculated and found to be in good agreement with the experimental data.     

Chemical immobilization of retinoic acid within poly(ε‐caprolactone) nanoparticles based on drug–polymer bioconjugates

All‐trans‐retinoic acid (RA) was chemically conjugated to biodegradable poly(ε‐caprolactone) (PCL₁₀; number‐average M_w ≈ 1250) via an ester linkage. The conjugation was carried out using N,N‐dicyclohexylcarbodiimide and 4‐dimethyl aminopyridine as a coupling agent. The molar ratio of the drug to the polymer was 1.11 as determined by ¹H‐NMR analysis. DSC and WAXD results showed that the formation of crystalline structures of RA was effectively suppressed by conjugation with PCL. The RA–PCL conjugates were formulated into nanoparticles by a spontaneous phase‐inversion technique. Morphological characteristics of the resultant nanoparticles and drug‐loading efficiencies were compared with those of free RA‐loaded nanoparticles. The drug‐loading efficiency of RA–PCL conjugates was almost 100%, while that of free RA was only ～12%. The majority of unconjugated RA was found to form undesirable free‐drug crystals out of nanoparticles, as observed by TEM analysis. This study demonstrates that the conjugation approach of RA to PCL can be an effective means to immobilize and encapsulate RA within nanoparticles for pharmaceutical applications. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1631–1637, 2003     

Organizing for remote consultations in health care?-?the production process

In health care we find a very complex production process related to the complexity of disease. New telecommunications have created a novel means of contact between patient and health care worker: the remote consultation. The remote consultation is unique, with a simultaneous flow of services from different organizations. It is conceivable that analysis of the production process of remote consultations may contribute to improved organization of the work. To obtain information on the little analysed production process of remote consultations, qualitative interviews were performed with 30 persons working in teledermatology, telepsychiatry, a telepathology frozen-section service, and tele-otolaryngology. The results show that managers in organizations planning telemedicine activity do not need to prepare the personnel by organizing communication on goal formulation and content for the remote consultations. For the single health care worker a remote consultation does not require more preparation than an ordinary consultation. The variation in type of images seen on the screen here does not seem to play a major role. Evaluation of each step mainly shows that the production process of remote consultations functions well. The most frequently mentioned problems are technical problems (which should not be exaggerated), but other problems also exist. Proposals for improvements were given, such as wishing that a technician was available, and improved booking systems. The main conclusion is that no major reorganization seems to be necessary for the production process of remote consultations. This type of telecooperation works well.     

Laparoscopic cholecystectomy

Traditional cholecystectomy has been the standard surgical treatment of the gallstone disease for more than 100 years. The technical development led to a new surgical procedure and its rapid acceptance. This is laparoscopic cholecystectomy. Its application is becoming widespread in therapy too. But most of the surgeons are lack of technical experiences in this field. Currently it restricts the indications those are anyway the same of standard cholecystectomy. Besides its many advantages, laparoscopic cholecystectomy has its own disadvantages and being an invasive procedure, there are possibilities of complications. The latest can be reduced by the adequate choice of patients, the careful learning of the operative technic and by turning to open surgery (conversion) when it is necessary. Its morbidity is nearly equal to complications of standard cholecystectomy, but mortality rate is lower (0.05-0.2%). Our morbidity of performed 300 laparoscopic cholecystectomies was 6.4%. We had no death. The hospitalization became as short as 4 days. Our early clinical results (90%) are the same of traditional cholecystectomy. Laparoscopic cholecystectomy as a new surgical procedure involves the efficiency of the standard cholecystectomy and the noninvasive endoscopic technic. Laparoscopic cholecystectomy performed by well trained surgeons is a safe surgical procedure, its early results are excellent and makes the choice of surgical treatment, used in bile surgery richer.