Liposomes coated with thiolated chitosan enhance oral peptide delivery to rats

The aim of the present study was the in vivo evaluation of thiomer-coated liposomes for an oral application of peptides. For this purpose, salmon calcitonin was chosen as a model drug and encapsulated within liposomes. Subsequently, the drug loaded liposomes were coated with either chitosan–thioglycolic acid (CS–TGA) or an S-protected version of the same polymer (CS–TGA–MNA), leading to an increase in the particle size of about 500 nm and an increase in the zeta potential from approximately − 40 mV to a maximum value of about + 44 mV, depending on the polymer. Coated liposomes were demonstrated to effectively penetrate the intestinal mucus layer where they came in close contact with the underlying epithelium. To investigate the permeation enhancing properties of the coated liposomes ex vivo, we monitored the transport of fluoresceinisothiocyanate-labeled salmon calcitonin (FITC-sCT) through rat small intestine. Liposomes coated with CS–TGA–MNA showed the highest effect, leading to a 3.8-fold increase in the uptake of FITC-sCT versus the buffer control. In vivo evaluation of the different formulations was carried out by the oral application of 40 μg of sCT per rat, either encapsulated within uncoated liposomes, CS–TGA-coated liposomes or CS–TGA–MNA-coated liposomes, or given as a solution serving as negative control. The blood calcium level was monitored over a time period of 24 h. The highest reduction in the blood calcium level, to a minimum of 65% of the initial value after 6 h, was achieved for CS–TGA–MNA-coated liposomes. Comparing the areas above curves (AAC) of the blood calcium levels, CS–TGA–MNA-coated liposomes led to an 8.2-fold increase compared to the free sCT solution if applied orally in the same concentration. According to these results, liposomes coated with S-protected thiomers have demonstrated to be highly valuable carriers for enhancing the oral bioavailability of salmon calcitonin.     

Development of controlled drug release systems based on thiolated polymers.

The purpose of the present study was to generate mucoadhesive matrix-tablets based on thiolated polymers. Mediated by a carbodiimide, L-cysteine was thereby covalently linked to polycarbophil (PCP) and sodium carboxymethylcellulose (CMC). The resulting thiolated polymers displayed 100+/-8 and 1280+/-84 micromol thiol groups per gram, respectively (means+/-S.D.; n=6-8). In aqueous solutions these modified polymers were capable of forming inter- and/or intramolecular disulfide bonds. The velocity of this process augmented with increase of the polymer- and decrease of the proton-concentration. The oxidation proceeded more rapidly within thiolated PCP than within thiolated CMC. Due to the formation of disulfide bonds within thiol-containing polymers, the stability of matrix-tablets based on such polymers could be strongly improved. Whereas tablets based on the corresponding unmodified polymer disintegrated within 2 h, the swollen carrier matrix of thiolated CMC and PCP remained stable for 6.2 h (mean, n=4) and more than 48 h, respectively. Release studies of the model drug rifampicin demonstrated that a controlled release can be provided by thiolated polymer tablets. The combination of high stability, controlled drug release and mucoadhesive properties renders matrix-tablets based on thiolated polymers useful as novel drug delivery systems.     

Calcium sulfate matrix as local antibiotic carrier in the mastoid

We describe the use of calcium sulfate beads as antibiotic carrier in a patient, who suffered from chronic mastoiditis with consecutive otogenic meningitis due to Burkholderia cenocepacia. Our findings suggest a possible role of calcium sulfate matrix as a local antibiotic carrier in the mastoid in complicated mastoiditis cases.     

Efficiency of glutamyl peptide polymers as plasma volume extenders

A series of polymers of polyglutamic acid have been tested as plasma volume expanders. The results indicate that those polymers prepared from backbones of 40,000 molecular weight or over and side chains of 3,000 molecular weight or over, will have plasma volume retention half-life of 15 hours or longer. Measurements of the oncotic efficiency of these polymers in vivo indicated a blood stream fluid retention of approximately 51 ml./gm. of polymer. Similar measurements of polymer-serum albumin solutions in vitro showed a retention of 52 ml./gm. of polymer. The clinical response to infusion of solutions of these polymers indicated no untoward pharmacological properties. Although the number of trials presented is too small for ultimate conclusion regarding either the physiological or clinical effects of these polymers, they do provide a strong indication of the desirability of further clinical testing of this polymer and a sound basis on which to plan the larger scale preparation of polymer. Both measures are currently under way.     

Comparison of monomeric and oligomeric transferrin as potential carrier in oral delivery of protein drugs.

Oligomeric transferrin (Tf) was used to investigate the effect that cross-linking of transferrin receptors (TfR) has on intracellular trafficking of the Tf-TfR complex and to determine whether or not the Tf-oligomer would be a better carrier than monomeric Tf for the oral delivery of protein drugs. The intracellular retention and transcytosis of the Tf-oligomer was determined by performing pulse chase studies on enterocyte-like Caco-2 cells. The intracellular retention of the Tf-oligomer was 2-fold higher than that of monomeric Tf while there was no significant difference in transcytosis. However, in vivo studies in CF-1 mice showed that the plasma concentrations of Tf from the orally administered Tf-oligomer were approximately 2-, 3- and 60-fold higher than that of orally administered monomeric Tf at 24, 48 and 72 h post-administration, respectively. In addition, the retention of the Tf-oligomer in the intestine was higher than that of monomeric Tf, which was consistent with in vitro studies. Insulin (In), when conjugated to the Tf-oligomer (Agg-Tf-S-S-In), was more effective than monomeric Tf-In conjugate (Mono-Tf-S-S-In) in reducing blood glucose levels when orally administered to streptozotocin (STZ)-induced diabetic rats. Post-oral administration of Agg-Tf-In, a delayed onset and prolonged hypoglycemic effect was observed. These results demonstrate that the cross-linking of TfR induced by the binding of the oligomeric Tf alters the intracellular trafficking and increases the intracellular retention of Tf-TfR complexes in polarized Caco-2 cells. The alteration of TfR trafficking could conceivably have caused the increase of insulin transport across the intestinal barrier when Agg-Tf-S-S-In was administered orally to STZ-induced diabetic rats. The delayed onset and prolonged effect of Agg-Tf-S-S-In in hypoglycemia strongly suggests that the Tf-oligomer can act as a sustained release carrier in the oral delivery of protein and peptide drugs.     

骨基质载体材料的生物学特点及其临床应用

背景：骨组织工程支架材料中的骨基质载体材料为骨缺损修复治疗提供了更为有效的方法。目的：重点介绍天然衍生骨载体材料-冻干脱钙骨基质、脱蛋白骨基质、脱细胞骨基质在骨组织工程中的应用。方法：以＂骨组织工程、冻干脱钙骨基质、脱蛋白骨基质、脱细胞骨基质、骨缺损;bone tissue engineering,scaffold materials,demineralized bone matrix,deprotein bone matrix,acellular bone matrix,bone defect＂为检索词,由第一作者检索1994/2010PubMed、CNKI及万方数据库等与骨组织工程领域有关的权威性文献。结果与结论：冻干脱钙骨基质、脱蛋白骨基质及脱细胞骨基质均具有良好的生物相容性、极低的抗原性、无细胞毒性,作为骨组织工程载体材料,保留了骨的天然属性,具有多孔隙结构,可降解性及良好骨传导作用,为骨缺损的治疗开辟了一条新途径。     

骨基质载体材料的生物学特点及其临床应用

背景:骨组织工程支架材料中的骨基质载体材料为骨缺损修复治疗提供了更为有效的方法。目的:重点介绍天然衍生骨载体材料-冻干脱钙骨基质、脱蛋白骨基质、脱细胞骨基质在骨组织工程中的应用。方法:以"骨组织工程、冻干脱钙骨基质、脱蛋白骨基质、脱细胞骨基质、骨缺损;bone tissue engineering,scaffold materials,demineralized bone matrix,deprotein bone matrix,acellular bone matrix,bone defect"为检索词,由第一作者检索1994/2010PubMed、CNKI及万方数据库等与骨组织工程领域有关的权威性文献。结果与结论:冻干脱钙骨基质、脱蛋白骨基质及脱细胞骨基质均具有良好的生物相容性、极低的抗原性、无细胞毒性,作为骨组织工程载体材料,保留了骨的天然属性,具有多孔隙结构,可降解性及良好骨传导作用,为骨缺损的治疗开辟了一条新途径。     

The debate regarding continuous use of oral contraceptives.

OBJECTIVE: To determine whether oral contraceptives (OCs) can be used safely in a continuous manner to prevent monthly withdrawal bleeding. DATA SOURCES: Search of MEDLINE (1966-2000), International Pharmaceutical Abstracts (1970-2000), and the Internet. DATA SYNTHESIS: Several prospective studies have assessed the efficacy of continuous cycle OCs in preventing monthly withdrawal bleeding. Monophasic OCs are useful for this purpose. In studies using traditional OC regimens as a control, patients receiving continuously administered OCs experienced more breakthrough bleeding and spotting. Continuous use of OCs decreased headache and other menstruation-associated symptoms. No long-term trials have assessed the impact of continuous use of OCs on risk of cancer, thromboembolic disease, or fertility, concems raised by opponents of the method. CONCLUSIONS: From the data available, continuous use of OCs is an effective method for delaying withdrawal bleeding. Long-term safety data are not available.     

羟基磷灰石/磷酸三钙复合材料作为细胞载体的实验研究

目的:羟基磷灰石/磷酸三钙(HA/TCP)复合材料在组织工程载体中的实验研究,为基质材料表面改性提供实验基础。方法:应用人骨髓基质细胞(hBMSCs)和脐静脉内皮细胞(UVECs)和HA/TCP进行混合培养,应用光学显微镜、荧光显微镜及扫描电子显微镜对其进行观察。结果:人骨髓基质细胞和脐静脉内皮细胞在HA/TCP表面均生长良好,并可观察到细胞长入基质材料微孔内的改变。结论:HA/TCP复合材料可作为细胞移植的载体。     

小肠黏膜下层无细胞基质作为阴道平滑肌细胞载体的可行性

背景:目前国内外用于阴道组织工程研究的主要支架材料聚乙醇酸存在降解过快等缺陷.天然脱细胞支架材料尤其是小肠黏膜下层逐渐成为组织工程研究的重点.目的:探索用猪小肠黏膜下层基质作为组织工程学阴道细胞载体的可行性.方法:取新西兰雌兔,分离出阴道平滑肌组织块,组织块+酶消化法原代培养阴道平滑肌细胞.体外培养传代后作为种子细胞接种于自制猪小肠黏膜下层基质体外联合培养,倒置显微镜动态观察细胞形态及生长增殖情况,分别于1,2,3,4周时取标本,行组织学检查.结果与结论:①体外成功培养出阴道平滑肌细胞,倒置显微镜下,见培养的阴道平滑肌细胞呈现长梭状,细胞集结于培养皿上形成典型的"峰和谷"样构型.②黏膜下层无细胞基质外观呈白色,半透明,有一定韧性.苏木精-伊红染色未见细胞成分存在.③阴道平滑肌细胞-肠黏膜下层标本切片苏木精-伊红染色后,光镜下可见细胞成分逐渐增多,由表浅向深层部位生长.④阴道平滑肌细胞-肠黏膜下层标本切片采用抗兔平滑肌α-肌动蛋白单克隆抗体免疫组化染色后,均可见抗兔α-Actin的阳性细胞.结果初步证明了猪小肠黏膜下层基质可作为一种平滑肌细胞载体.     

Chitosan-graft-polyethylenimine as a gene carrier.

Chitosans have been proposed as biocompatible alternative cationic polymers that are suitable for non-viral delivery. However, the transfection efficiency of chitosan-DNA nanoparticles is still very low. To improve transfection efficiency, we prepared chitosan-graft-polyethylenimine (CHI-g-PEI) copolymer by an imine reaction between periodate-oxidized chitosan and polyethylenimine (PEI). The molecular weight and composition of the CHI-g-PEI copolymer were characterized, using multi-angle laser scattering (GPC-MALS) and (1)H nuclear magnetic resonance ((1)H NMR), respectively. The copolymer was complexed with plasmid DNA (pDNA) in various copolymer/DNA (N/P) charge ratios, and the complex was characterized. CHI-g-PEI showed good DNA binding ability and high protection of DNA from nuclease attack. Also, with an increase in charge ratio, the sizes of the CHI-g-PEI/DNA complex showed a tendency to decrease, whereas the zeta potential of the complex showed an increase. The CHI-g-PEI copolymer had low cytotoxicity, compared to PEI 25K from cytotoxicity assays. At high N/P ratios, the CHI-g-PEI/DNA complex showed higher transfection efficiency than PEI 25K in HeLa, 293T and HepG2 cell lines. Our results indicate that the CHI-g-PEI copolymer has potential as a gene carrier in vitro.     

羟基磷灰石/磷酸三钙复合材料成骨细胞载体的体外实验

目的:研究人骨髓基质细胞(humanbonemarrowstromalcells,hBMSC)在复合材料的表面生长和增殖情况,为成骨细胞载体研究和材料表面改性提供直接依据。方法:进行原代人骨髓基质细胞培养,传代至第3代后,将hBMSC和羟基磷灰石(hydroxyapatite,HA)/磷酸三钙(tricalciumphosphate,TCP)进行混合培养,采用倒置显微镜、荧光显微镜和扫描电镜观察形态,MTT测定细胞增殖情况,测定碱性磷酸酶了解分化情况。结果:hBMSC在HA/TCP复合材料上生长、增殖良好,并可见细胞向材料孔内生长,对碱性磷酸酶无明显影响。结论:HA/TCP复合材料是良好的骨组织工程的细胞载体,为进一步临床应用提供了基础。     

Clinical use of selective decontamination: The concept

Infections can be classified according to: (1) the type of offending microorganism (virus, bacteria, fungi, parasites), (2) according to the clearance by the defence system (T cell dependent/independent) and (3) in case bacteria are the causative agents in Gram-positive and Gram-negative infections. The latter classification in Gram-positive and Gram-negative infections has appeared to have a practical consequence. Gram-negative bacteria, often involved in major infections and yeasts, appear to play practically no role in the intestinal ecological system. Consequently, it is nowadays increasingly attempted to eliminate Gram-negative bacteria and yeasts selectively from the digestive tract with antimicrobial agents. Selective suppression of Gram-positive bacteria may severely affect the ecosystem of the digestive tract. This selective suppression of Gram-negatives must be continued as long as patients are immunocompromised (locally or systemically) and is called selective decontamination of the digestive tract.     

Clinical use of selective decontamination: The concept

Infections can be classified according to: (1) the type of offending microorganism (virus, bacteria, fungi, parasites), (2) according to the clearance by the defence system (T cell dependent/independent) and (3) in case bacteria are the causative agents in Gram-positive and Gram-negative infections. The latter classification in Gram-positive and Gram-negative infections has appeared to have a practical consequence. Gram-negative bacteria, often involved in major infections and yeasts, appear to play practically no role in the intestinal ecological system. Consequently, it is nowadays increasingly attempted to eliminate Gram-negative bacteria and yeasts selectively from the digestive tract with antimicrobial agents. Selective suppression of Gram-positive bacteria may severely affect the ecosystem of the digestive tract. This selective suppression of Gram-negatives must be continued as long as patients are immunocompromised (locally or systemically) and is called selective decontamination of the digestive tract.     

Contemporary use of the disease concept: II. The question of anemia

Of 105 admissions to a medical service, 64 involved anemia (defined as a hematocrit value of less than 38%) at some time during the admission. Chart review revealed that the disease concept was not being used, as most of the anemias were unnoticed or undiagnosed, and most of the diagnoses that were made were incorrect.     

The use of linear models and matrix least squares in clinical chemistry.

We present a unified approach to the use of linear models and matrix least squares with the intention of providing a better understanding of the techniques themselves and of the statistics that arise from these techniques as they are used in clinical chemistry. Emphasis is placed on the importance of appropriate experimental designs and adequately precise measurement processes for efficiently obtaining the desired information.     

The use of high-power lasers in oral surgery

This study describes the treatment of 2989 patients with different type of lasers. The argon laser beam was used in 57 cases for procedures ranging from portwine stains, telangiectasias, and angiofibromas to other vascular lesions. Eighty-four operations including treatment of leukoplakia and hemangioma were performed using the Nd YAG laser. An additional 53 operations were performed using the combined Nd:YAG laser beam and 2795 operations were done using the carbon dioxide laser on precancerous states and other white lesions, benign tumors and tumor-like states, malignant tumors, and other lesions. The laser procedures were performed under local anesthesia. Operations were rapid and bloodless yielding both excellent cosmetic and functional results. The experience gained with this group of patients suggests that the ideal cases for laser treatment were leukoplakia, hemangiomas, and other vascular tumors and lesions of the face and the oral cavity, and clotting disturbance.