Biodistribution of clodronate and liposomes used in the liposome mediated macrophage 'suicide' approach

Clodronate (Cl2MBP; dichloromethylene-bisphosphonate)-containing liposomes are used to investigate the role of macrophages in immune and non-immune defense mechanisms by elimination of these macrophages followed by functional studies. The present studies characterize such liposomes in terms of the leakage of clodronate and the biodistribution of both the encapsulated drug and the liposomal carrier. The distribution of liposomes was studied using a radioactively labelled lipid phase marker (111In-DTPA-SA) and the distribution of the encapsulated drug was examined following injection of radioactively labelled clodronate (99mTc-Cl2MBP). Furthermore, the biodistribution of variously composed multilamellar liposomes (EPC/Chol molar ratio 7:1.3 or 7:7; EPC/Chol/PS 7:1.3:1 or 7:7:1; EPC/Chol/M 7:2:1; EPC/Chol/M-PE 7:2:1) after intravenous injection was investigated. The findings suggest that only one third of the originally entrapped clodronate was still encapsulated in the liposomes at the time of ingestion by the macrophages in the liver and spleen after intravenous injection of the clodronate containing liposomes. 3 h after injection no clodronate could be detected in the circulation.

Molecular dynamics study of phospholipase A2 on a membrane surface

The desolvation of lipid molecules in a complex of the enzyme human synovial phospholipase A2 with a lipid membrane is investigated as a mechanism that enhances the overall activity of the enzyme. For this purpose the interaction of the enzyme phospholipase A2 with a dilauryl-phosphatityl-ethanolamin (DLPE) membrane monolayer surface has been studied by means of molecular dynamics simulations. Two enzyme-membrane complexes, a loose and a tight complex, are considered. For comparison, simulations are also carried out for the enzyme in aqueous solution. The conformation, dynamics, and energetics of the three systems are compared, and the interactions between the protein and lipid molecules are analyzed. Free energies of solvation are calculated for the lipid molecules in the enzyme-membrane interface. Along with the calculated dielectric susceptibility at this interface, the results show the desolvation of lipids in a tightly bound, but not in a loosely bound protein-membrane complex. The desolvated lipids are found to interact mainly with hydrophobic protein residues, including Leu-2, Val-3, Ala-18, Leu-19, Phe-24, Val-31, and Phe-70. The results also explain why the turnover rate of phospholipase A2 complexed to a membrane is enhanced after a critical amount of negatively charged reaction product is accumulated.

Fibroblast growth factor receptor 3 is a negative regulator of bone growth

Endochondral ossification is a major mode of bone that occurs as chondrocytes undergo proliferation, hypertrophy, cell death, and osteoblastic replacement. We have identified a role for fibroblast growth factor receptor 3 (FGFR-3) in this process by disrupting the murine Fgfr-3 gene to produce severe and progressive bone dysplasia with enhanced and prolonged endochondral bone growth. This growth is accompanied by expansion of proliferating and hypertrophic chondrocytes within the cartilaginous growth plate. Thus, FGFR-3 appears to regulate endochondral ossification by an essentially negative mechanism, limiting rather than promoting osteogenesis. In light of these mouse results, certain human disorders, such as achondroplasia, can be interpreted as gain-of-function mutations that activate the fundamentally negative growth control exerted by the FGFR-3 kinase.

Role of c-jun induction in the glucocorticoid-evoked apoptotic pathway in human leukemic lymphoblasts

Accumulated evidence suggests tI AP-1 family in CEM cell clones exposed to the glucocorticoid dexamethasone (Dex) has been investigated. Dex is known to cause apoptosis of lymphoid cells in general and of sensitive human lymphoid CEM cell clones in particular. This study finds that Dex induces c-jun mRNA and cJun protein in cells of the sensitive clone CEM-C7 and of the lysis-sensitive OEM hybrid clone H10. CEM-O7 cells were screened for several other Jun/Fos family proteins. Both cFos and JunD were expressed but were unaffected by the steroid, and JunB was not detected. In the continual presence of Dex the induction of cJun began about 6 h after addition of Dex, reached a maximum by 24 h, and plateaued for 72 h, while cell death did not begin until 24-48 h. In clone OEM-Cl cells, which contain glucocorticoid receptor (GR) but are resistant to lysis by Dex, the basal, and even the fully induced, cJun levels are below the basal levels in OEM-07 and H10 cells. To test the hypothesis that cJun plays an important role in steroid-evoked apoptosis, stable transfectants expressing Dex-regulable antisense c-jun RNA were established. Mass cultures of these cells showed reduced sensitivity to Dex, and in three of three clones tested, complete resistance to Dex was obtained. This occurred even though endogenous genes (GR, c-jun) normally responsive to Dex were still inducible, indicating that the GR and basic glucocorticoid response apparatus were intact. It is concluded that Dex induces cJun levels in sensitive OEM cells before cell death and that this induction plays a role in the apoptotic process.

Observation of gas-phase molecular dications formed from neutral organics in solution via the controlled-current electrolytic process inherent to electrospray

This article reports the first electrospray (ES) mass spectrometry observation of molecular dications that were formed in solution by sequential one-electron oxidation of the neutral molecules [viz., nickel(II) and cobalt(II) octaethylporphyrin] via the controlled-current electrolytic (CCE) process inherent to electrospray. Dication formation was found to require (1) the addition of electrolyte to the sample solution, which increased the magnitude of the ES current and, therefore, increased the extent of analyte electrolysis in the ES capillary, (2) a relatively low solution flow rate, which increased the electrolysis time (i.e., the time the analyte remained in the capillary), thereby providing more time for the analytes to diffuse to the metal-solution interface and react, and (3) the use of a platinum ES capillary, which, because it is difficult to oxidize, increased the proportion of the faradaic current that might be provided by electrolysis of solution species compared to that proportion available when the typical stainless steel capillary is used. These interpretations of the data are made on the basis of the known characteristics of the CCE process inherent to ES, supplementary data obtained from direct solution-phase observation of the metalloporphyrin redox products formed within the different metal ES capillaries by means of a novel ES ion source, and off-line cyclic voltammetry studies of the metalloporphyrins performed by using platinum and stainless steel working electrodes.

[Effects of assisted ovarian stimulation with leuprolide acetate on alterations of plasma estradiol levels and newly synthesized endometrial proteins]

OBJECTIVE

To evaluate the effects of leuprolide acetate (LA)-assisted ovarian stimulation on endometrial protein synthesis in hamsters.

METHODS

Hamsters were treated separately with three different regimens: (1) 40 IU of pregnant mare's serum gonadotropin (PMSG) followed by 100 IU of hCG after 52 hours (PMSG alone group). (2) Same volumes of normal saline on the same schedule (control group). (3) 40 micrograms of LA daily prior to the same regimen of PMSG-hCG treatment in order to down-regulate the pituitary-ovarian functions (LA-PMSG group). The newly synthesized endometrial proteins were characterized and quantitated in vitro by 3H-leucine incorporation test and 10% SDS-PAGE technique.

RESULTS

The levels of newly synthesized 3H-labelled endometrial proteins were not different between LA-PMSG and control groups. However, those of low and middle molecular weight (< 31,000 and 45,000) proteins in the PMSG alone group were significantly lower than the levels in both LA-PMSG and control groups (P < 0.05, P < 0.01).

CONCLUSIONS

The addition of LA in ovarian stimulation protocol resulted in more physiological endometrial protein synthesis. This phenomenon may causally related to higher pregnancy rate when applied in vitro fertilization-embryo transfer programs.

[Study on some susceptible genes of systemic lupus erythematosus in Han nationality of China]

In order to explore the allelic polymorphism of HLA-DR and TNF B loci and susceptibility to systemic lupus erythematosus (SLE) in the Han nationality of northern China with the aid of methods of polymerase chain reaction/sequence specific primers (PCR/SSP) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) respectively. The findings from a case-control study on 151 blood samples (45 from the cases and 106 from the controls) indicated that there were significantly higher frequency of DR2 (P < 0.05, RR = 1.56) and DR3 (P < 0.01, RR = 2.69), which represent candidate susceptible genes or useful markers for SLE. The DR5 allele in the samples (P < 0.05, RR = 0.43) might be an antagonistic or protective allele, or a marker for such allele. The frequency of TNF B * 1 and TNF B * 2 alleles was investigated in 45 SLE patients and 80 healthy controls and it was found that the frequency of TNF B * 2 allele was significantly higher in the patient group (P < 0.05, RR = 1.84). It might also be a suspicious susceptible allele or a marker for such allele. The frequency of HLA polymorphisms in various clinical/immunological subsets of our patient population was also determined. Clinical findings used include plasma SC5b-9 level, SSA, SSB, Sm, RNP, ANA antibodies, and SLE complications (SLE nephritis, pneumonia & encephalopathy). It turned out that there was a positive association between HLA-DR2 allele and SLE nephritis (P < 0.05, RR = 1.32).

[Morphometric studies of effects of clomiphene citrate on histological characteristics of proliferative endometrium]

OBJECTIVES

To analyse quantitatively the effects of clomiphene citrate (CC) on histological characteristics of proliferative endometrium.

METHODS

Endometrium biopsies were performed on day 12th of both natural and CC cycles in 14 infertile patients. Nuclear size, shapes and DNA contents of epithelial and glandular epithelial cells, stromal cells were measured or calculated after HE and Feulgeu staining by computerized image analysis technique. Results were compared before and after CC treatment.

RESULTS

The average area, girth and maximal diameter of the nucler of glandular and epithelial cells in CC cycles were significantly smaller than those of natural cycles (P < 0.05), while the shape factor of stromal nuclea in CC cycles was larger than the natural ones (P < 0.05). DNA contents of glandular, epithelial and stromal nuclea in CC cycles were also smaller than those of natural cycles (P < 0.02). The difference of nuclear DNA content between the 2 cycles was positively correlated with the difference of nuclear area of glandular and epithelial cells (P < 0.01).

CONCLUSIONS

CC treatment inhibited the endometrial mitosis and proliferation. This effects may begin at the stage of DNA synthesis, therfore DNA contents of endometrial glandular and stromal nuclea also decreased. The action of CC may be related to estrogen receptor synthesis.

[Quantitative determination of magnolol and honokiol in baoji pill by HPLC]

A HPLC method for the determination of magnolol and honokiol in Baoji Pill has been established. The method can be used to control the quality of Boji Pill.

[Determination of puerarin in radix Puerariae and yufengningxin tablets by HPLC]

The contents of puerarin in Radix Puerariae and Yufengningxin Tablets were determined by HPLC. The average rates of recovery were 97.19% and 100.68% respectively, and RSD 1.05% and 1.31% respectively.

The ATF site mediates downregulation of the cyclin A gene during contact inhibition in vascular endothelial cells

Contact inhibition mediates monolayer formation and withdrawal from the cell cycle in vascular endothelial cells. In studying the cyclins--key regulators of the cell cycle--in bovine aortic endothelial cells (BAEC), we found that levels of cyclin A mRNA decreased in confluent BAEC despite the presence of 10% fetal calf serum. We then transfected into BAEC a series of plasmids containing various lengths of the human cyclin A 5' flanking sequence and the luciferase gene. Plasmids containing 3,200, 516, 406, 266, or 133 bp of the human cyclin A promoter directed high luciferase activity in growing but not confluent BAEC. In contrast, a plasmid containing 23 bp of the cyclin A promoter was associated with a 65-fold reduction in activity in growing BAEC, and the promoter activities of this plasmid were identical in both growing and confluent BAEC. Mutation of the activating transcription factor (ATF) consensus sequence at bp -80 to -73 of the cyclin A promoter decreased its activity, indicating the critical role of the ATF site. We identified by gel mobility shift analysis protein complexes that bound to the ATF site in nuclear extracts from growing but not confluent BAEC and identified (with antibodies) ATF-1 as a binding protein in nuclear extracts from growing cells. Also, ATF-1 mRNA levels decreased in confluent BAEC. Taken together, these data suggest that the ATF site and its cognate binding proteins play an important role in the downregulation of cyclin A gene expression during contact inhibition.

[Determination of andrographolide in medicinal preparations by HPLC]

A HPLC procedure has been developed to determine andrographolide in Fencishui. The sample was analyzed on a YWG-C18 column, with methanol-water (38:62) as the mobile phase, and detected at 225nm. The average recovery was 98.42% and RSD 1.69%.

[Foraminal and extraforaminal lumbar disc herniations]

Between August 1992 to November 1994, 7 cases of foraminal and 3 cases of extraforaminal lumbar disc herniation were diagnosed and operated on, which represented an incidence of 4.1% of all operated lumber disc herniations. Contrasted to the typical disc herniation, foraminal and extraforaminal disc herniations involved the upper nerve root mainly. The dominent symptoms and signs were severe anterior thigh and lower leg pain, positive femoral nerve strech test, impairment of knee jerk reflex and weakness of the quadriceps muscle. Sequestration and extrusion were the most common type of disc pathology. CT/MRI showed the protruded disc in and outside of the foramen clearly. It was thought to be ideal method for the precise diagnosis and guidance of surgery. However the variations of the nerve root or other diseases related to it should be identified. All of the 10 cases underwent surgical treatment with the approach by outer edge of pars interarticularis in 8. The result was encouraging with complete improvement in 8 cases, obvious improvement in 1 case, and partial improvement in another case. It was found that the approach had the advantage of good exposure and effect with the minimal destruction of pars interarticularis and facet joint which would not give rise to lumbar instability.

Mucosal IgA response to rectally administered antigen formulated in IgA-coated liposomes

Ferritin, a soluble model antigen, was used to test whether liposomes can provide an effective delivery vehicle for mucosal immunization via the rectum, and whether the local colonic/rectal secretory immune response to antigen in liposomes can be enhanced by immunoadjuvants. The colonic/rectal IgA response to liposomal ferritin was significantly enhanced over the response to free ferritin but only when cholera toxin (CT) was present as adjuvant. The presence of IgA on the liposome surface increased the uptake of liposomes into Peyer's patch mucosa, and the local rectal/colonic immune response to ferritin about 5-fold over uncoated liposomes. These results show that (1) liposomes co-administered with immunoadjuvants can be used for mucosal immunization via the rectum. (2) Cholera toxin is an effective immunoadjuvant in the rectal/colonic mucosa. (3) IgA can enhance the local secretory immune response to antigen in liposomes, apparently by increasing liposome uptake via M cells.

[The pathogenetic factors for neurogenic intermittent claudication caused by degenerative lumbar spinal stenosis]

The pathogenetic factors in 89 patients with typical neurogenic intermittent claudication caused by lumbar spinal stenosis were studied retrospectively. 75 patients had degenerative lumbar spinal stenosis, and 67 had unilateral nerve root canal stenosis. In most patients, the stenotic location was found at the entrance zone of nerve root canal (75/89), involving only a single level (60/89) mostly at L4.5. The pathogenetic factors for degenerative lumbar spinal stenosis were degenerative changes of lumbar disc only (55/89), and those for hypertrophy of facet joints (22/89), thickened ligamentum flavum (11/89), and spondylolis thesis (10/89). All patients were operated on: 57 of them had less invasive procedures. The excellent and good early follow-up results were noted in 73% of the patients (65/89). The authors emphasized that the surgical treatment of lumbar spinal stenosis should be as less invasive as possible rather than a tranditional extensive lumbar laminectomy.

Induction of vascular endothelial growth factor gene expression by interleukin-1 beta in rat aortic smooth muscle cells

Vascular endothelial growth factor (VEGF) is a potent and specific mitogen for vascular endothelial cells and promotes neovascularization in vivo. To determine whether interleukin-1 beta (IL-1 beta), which is present in atherosclerotic lesions, induces VEGF gene expression in vascular smooth muscle cells, we performed RNA blot analysis on rat aortic smooth muscle cells (RASMC) with a rat VEGF cDNA probe. IL-1 beta increased VEGF mRNA levels in RASMC in a time- and dose-dependent manner. As little as 0.1 ng/ml IL-1 beta increased VEGF mRNA levels by 2-fold and 10 ng/ml IL-1 beta increased VEGF mRNA by 4-fold. We also measured the half-life of VEGF mRNA and performed nuclear run-on experiments before and after addition of IL-1 beta to see if IL-1 beta increased VEGF mRNA levels by stabilizing the mRNA or by increasing its rate of transcription. The normal, 2-h half-life of VEGF mRNA in RASMC was lengthened to 3.2 h (60%) by IL-1 beta, and IL-1 beta increased the rate of VEGF gene transcription by 2.1-fold. In immunoblot experiments with an antibody specific for VEGF, we found that IL-1 beta increased VEGF protein levels in RASMC by 3.3-fold. Together these data indicate that IL-1 beta induces VEGF gene expression in smooth muscle cells. This IL-1 beta-induced expression of VEGF may accelerate the progression of atherosclerotic lesions by promoting the development of new blood vessels.

Delivery of protein antigen to the major histocompatibility complex class I-restricted antigen presentation pathway

Major histocompatibility complex (MHC) class I-restricted antigen presentation normally requires a protein antigen to be synthesized in the cytosol of the antigen presenting cell (APC). Exogenous protein antigen could gain access to the class I presentation pathway if the protein is introduced into the cytosolic compartment of the APC. Approaches which release the protein antigen from endocytic vesicles have been employed to deliver protein antigen for the recognition by class I-restricted cytotoxic T lymphocytes (CTL). These include osmotic shock, electroporation, cationic and pH-sensitive liposomes. An alternative approach is to deliver a gene that encodes the protein antigen. In this case, the APC is transfected with a gene which synthesizes the "exogenous protein" in the cytosol. Delivery of protein antigen targeted for CTL induction in vivo follows a different strategy and generally requires an antigen carrier of lipidic/membranous nature, such as liposomes, immunostimulating complexes, and/or lipid conjugates. Macrophages that are responsible for scavenging the antigen play an important role in CTL induction. An optimal CTL inductive vaccine must contain other immuno-modulatory activities in addition to its activity in delivering antigen to the class I pathway. Attempts to attenuate viral infection and to improve anti-tumor immunity have been successful by delivering the exogenous antigen entrapped in liposomes. These animal model studies should be of great value in the development of potential vaccine formulation.

[Analysis of spatial clustering of disease]

It is difficult to determine whether there is spatial clustering of disease if the geographical distribution of population is unknown. Permutation test reported in the paper can be used as a method to judge the spatial clustering with unknown distribution of a random sample of cases. Comparison of difference in frequency of small distances between pairs of cases and controls can show whether there is spatial clustering of the disease.

[Research on corneal thickness at multi-points in normal and myopic eyes]

The corneal thickness of the center and other 24 points were measured in 31 normal eyes and 246 myopic eyes. The results show that the mean central corneal thickness of the normal eye is 541 +/- 45.29 microns and that of the myopic eye, 544 +/- 35.01 microns. There are no significant differences in the central corneal thickness in comparisons between the left and right eye, between the male and female, among various age groups, and among various degrees of refractive error. However, with the increase of age and increase of myopic refractive error, the central corneal thickness gradually becomes thinner. There are differences in thickness among various directions, the superior direction being the thickest and the temporal inferior, the thinnest. From the center to the limbus, the thickness of the cornea gradually increases, but the values of the increase of the thickness are various in various directions, that should be paid attention to in radial keratotomy.

Liposome-mediated cytoplasmic delivery of proteins: an effective means of accessing the MHC class I-restricted antigen presentation pathway

Different types of liposomes have been employed to deliver soluble antigen for processing and presentation in the major histocompatibility complex class I-restricted pathway. Anionic pH-sensitive liposomes as well as cationic liposomes efficiently sensitize antigen-presenting cells for recognition by the class I-restricted cytotoxic T lymphocytes (CTL). Cytoplasmic delivery of liposome-entrapped antigen from an endocytic compartment allows the exogenous antigen to gain access to the class I presentation pathway. Cytoplasmic delivery, however, is probably not the only mechanism by which liposomes induce the class I-restricted CTL priming in vivo. Macrophages play a central role in the processing of the liposome-encapsulated antigens. The processed antigen fragments are probably released by the macrophages and taken up by the nearby dendritic cells for antigen presentation. Collaboration between the two types of immune cells with the help of the appropriate costimulatory factors is the central theme for this hypothesis. In this case, the host immune system utilizes the similar mechanism for other membranous, particulate antigens to process and present the liposomal antigens.

The internal ventricular venting loop catheter. A new, simplified, single cannulation approach for a ventricular assist system

The internal ventricular venting loop (IVVL) catheter is a coaxial, two lumen, bidirectional flow cannula introduced peripherally and advanced intraluminally to the pulmonary artery by its flow directed, balloon tipped inner tubing in a right ventricular assist system (RVAS), or to the left ventricle over a guide wire under fluoroscopy in a left ventricular assist system (LVAS). Its use was successfully tested in six acute canine experiments using a small IVVL catheter. Hemodynamic responses to increasing roller pump flow rates, to a maximum of 1 L/min, were initially measured. Then, hemodynamic changes to 600 ml/min, after left anterior descending artery ligation (in IVVL-LVAS) and 300 ml/min after right coronary artery ligation (in IVVL-RVAS) were regularly recorded every 15 min until cardiac arrest. The IVVL-LVAS was able to significantly decrease the pulmonary capillary wedge pressure, while the IVVL-RVAS was able to significantly decrease the central venous pressure. The IVVL system was able to partially unload the ventricles and restore about 33-60% of the cardiac output. However, it could not effectively support the heart during arrest. Thus, the IVVL catheter can facilitate simple and effective single cannulation for either RVAS or LVAS. This approach may enable ordinary cardiac centers to make use of already available blood pumps for temporary, inexpensive, and less invasive application of partially assisted circulation when intra aortic balloon pump assistance fails.

Characterization and kinetics of MHC class I-restricted presentation of a soluble antigen delivered by liposomes

We describe in this report the characterization and kinetics of MHC class I-restricted presentation of a soluble antigen delivered by liposomes. pH-sensitive liposomes delivered ovalbumin (OVA) to the class I pathway more efficiently than pH-insensitive liposomes; the latter showed competence in the class I-restricted sensitization only when a large antigen loading dose was used. Such sensitization of EL4 cells resulted from substantial delivery of the ingested liposomal OVA to the cytosolic compartment as revealed with immunogold electron microscopy. Most of the ingested liposomal OVA were rapidly catabolized and released into the extracellular medium. The residual processed antigen took about 2 h to egress to the cell surface for recognition by CTL. The liposome-mediated antigen presentation exhibited a transient kinetics which was manipulable with antigen dose. Brefeldin A, an ER-to-Golgi transport inhibitor, strongly inhibited such presentation. The antigens displayed on the cell surface could also be removed by a brief acid wash of the cells and subsequently reappeared on the surface if an intracellular pool of antigen existed at the time of acid wash.

[Analysis of fatty acid composition of spotted fever group rickettsiae isolated in China by gas chromatography]

In present paper, fatty acid composition of seven Chinese isolates of SFG rickettsiae and six prototype strains of SFG rickettsiae were analyzed by GC-MS. Tested prototype strains of SFG rickettsiae were R. sibirica (strains 232 and 246), R. conorii (Simko), R. rickettsi (R), R. akari (Kaplan), R. australis (W58); Chinese isolates were An-84, Se-85, W-88 (human strain), MT-84, FT-84 (D. nuttalli strain), TO-85 (ova of nuttalli) and Chinese reference strain -JH-74 (D. nuttalli). They were propagated in yolk sacs of embryonated hen eggs and purified by centrifugation in a 30%-36%-42% discontinuous renografin density gradient. The fatty acid composition of selected strains of SFG rickettsiae was analyzed by gas chromatography, and then comparison being carried out by single linkage on mini-computer. Identification of the strains was performed based on the results obtained from GC-MS. Results showed that the fatty acid profiles of all the isolates from China were quantitatively similar to that of R. sibirica and quite different from other prototype strains of SFG rickettsiae.

Molecular dynamics study of the proton pump cycle of bacteriorhodopsin

Retinal isomerization reactions, which are functionally important in the proton pump cycle of bacteriorhodopsin, were studied by molecular dynamics simulations performed on the complete protein. Retinal isomerizations were simulated in situ to account for the effects of the retinal-protein interactions. The protein structure employed was that described in Nonella et al. [Nonella, M., Windemuth, A., & Schulten, K. (1991) Photochem. Photobiol. 54, 937-948]. We investigated two mechanisms suggested previously for the proton pump cycle, the 13-cis isomerization model (C-T model) and the 13,14-dicis isomerization model. According to these models, retinal undergoes an all-trans-->13-cis or an all-trans-->13,14-dicis photoisomerization as the primary step of the pump cycle. From the simulations emerged a consistent picture of isomerization reactions and their control through the retinal-protein interactions which favors the 13,14-dicis isomerization model. Electrostatic interactions between the protonated Schiff base and its counterion are found to direct the stereochemistry of retinal in the photocycle: this and other interactions steer retinal toward the 13,14-dicis geometry in the primary photoreaction, toward the 13-cis geometry after its deprotonation, and to the all-trans isomeric form after its reprotonation. We also propose a catalytic mechanism involving hydrogen bonding of the Schiff base to main chain oxygen atoms of Val-49 and Thr-89 for the 13-cis-->all-trans thermal reisomerization of retinal. The all-trans-->13-cis primary photoreaction required by the "C-T" model was found to be inhibited by the Schiff base-counterion interaction, but the possibility of such a reaction can not be excluded. In order to investigate the "C-T" model, we enforced an all-trans-->13-cis photoisomerization in a simulation and monitored the subsequent protein conformational changes. The effects of internal water molecules on retinal isomerization reactions were studied by placing 16 water molecules in the proton conduction channel. The results indicate that water affects the nature of the Schiff base counterion and the nature of the primary photoreaction. Water chains, formed between positively and negatively charged protein groups in the proton conduction channel, are suggested to be involved in the reprotonation and deprotonation of retinal.

Monophosphoryl lipid A enhances specific CTL induction by a soluble protein antigen entrapped in liposomes

Exogenous soluble antigen loaded in membranous vehicles including splenocytes and liposomes can induce a CD8+ cytotoxic T-lymphocyte (CTL) response in mice. Plain liposomes of simple composition, however, are not as effective as cellular vehicles such as splenocytes. In the present study it is shown that incorporation of monophosphoryl lipid A (MPL), a semisynthetic bacterial adjuvant, into liposomes enhanced the ability of liposomal ovalbumin (OVA) to prime for a specific CTL response. With the MPL formulation, the minimal antigen dose required for a detectable CTL induction was reduced about fivefold, and this approximated the required minimal dose of OVA loaded in the splenocytes. Moreover, liposomes containing MPL could induce a considerable level of CTL activity by either an intravenous, intramuscular or subcutaneous immunization protocol, whereas liposomes without MPL could only elicit such a response by an intravenous injection route. Subcutaneous injection of a mixture of liposomes containing MPL and liposomes containing antigen also elicited specific CTL activity. However, simultaneous subcutaneous administration of liposomal MPL and liposomal OVA at two distant sites did not prime the mice for a CTL response. These results indicate that MPL, although not necessarily incorporated in the same liposomes, must be in close proximity to the antigen to exert its adjuvant activity. Based on the results of this model antigen study, it is suggested that an optimal CTL inductive vaccine should include immunomodulatory adjuvant in addition to a class I pathway delivery vehicle such as liposomes.

Thermodynamic integration calculations of binding free energy difference for Gly-169 mutation in subtilisin BPN'

The binding free energy difference for the Gly-169-->Ala-169 (G169A) mutation in subtilism BPN' complexed with a tripeptide substrate analogue is explored using the thermodynamic integration approach. The structure of the mutant enzyme-substrate complex obtained from free energy simulation is in good agreement with experimental X-ray refinement. The near perfect reversibility is obtained in the present work for ensuring the correctness of the free energy calculations. The results of the binding free energy difference are close to similar experimental data.

Prolonged survival of thymoma-bearing mice after vaccination with a soluble protein antigen entrapped in liposomes: a model study

EG7-OVA cells are mouse thymoma EL4 cells stably transfected with the complementary DNA of chicken ovalbumin (OVA) and thus express OVA epitopes as a unique antigen. Cytotoxic T lymphocytes specific to OVA can be elicited by immunization of mice with OVA osmotically loaded into syngeneic splenocytes or entrapped in liposomes. Cytotoxic T lymphocytes thus induced can specifically cytolyse the EG7-OVA cells in vitro in an antigen-specific and major histocompatibility complex-restricted manner. In the present study, we have examined in this model system whether immunization with liposomal OVA can protect mice against tumors induced by EG7-OVA cells. Vaccination with OVA either entrapped in liposomes or osmotically loaded in the syngeneic splenocytes prolonged the survival of mice which had been challenged with EG7-OVA cells, but not those mice challenged with the parent EL4 cells. The antitumor effect was attributed to the induced OVA-specific cytotoxic T lymphocyte activity, since other forms of acquired immunity such as interaction of tumor cells with specific antibody could not be detected. Our results demonstrate that immunization with antigen incorporated in liposomes could be a useful means of inducing a protective antitumor response.

[Purification of the ninth component of human complement (C9)]

A large amount of human C9 was purified from plasma by the following procedures: 1) Polyethylene glycol precipitation; 2) Depletion of plasminogen by passing over an L-lys-sepharose column; 3) DEAE-sephadex A-50 chromatography; and 4) Hydroxylapatite (HA) chromatography. The method of C9 purification was improved by altering the column-elution conditions and by the establishment of a novel method for preparing high-flow-rate HA. As a result, the rate of recovery of C9 was high (28.2%) and no impurities were detected either on gel electrophoretic or immunochemical examination. The hemolytic activity of purified C9 was retained.

Induction of cytotoxic T lymphocytes in vivo with protein antigen entrapped in membranous vehicles

Intravenous administration of APC such as splenocytes loaded with a soluble protein Ag has been shown to prime for an Ag-specific CTL response. It is thought that the APC directly presents loaded Ag in a MHC-restricted manner. However, it is demonstrated in this study that allogeneic splenocytes, MHC-free RBC, and even synthetic lipid vesicles (liposomes) after loading with OVA can elicit an OVA-specific and MHC-restricted CTL response. Biodistribution studies of these Ag-associated vehicles showed that the liver, spleen, and lung were the major organs responsible to scavenge these carriers, suggesting that the monocyte-macrophage system was involved in the Ag presentation for CTL. Depletion of macrophages by a specific macrophage killer, Cl2MDP, containing liposomes, abolished the CTL induction by immunization with OVA Ag carried by these vehicles except the induction by syngeneic splenocytes. Thus, the syngeneic splenocytes present Ag directly to the T cells, but other membranous vehicles carry the Ag to the host APC including macrophages, which then present it to the T cells. These results indicate that formulation of an Ag in membranous/colloidal vehicles may be a way to prime for a CTL response.

Induction of cytotoxic T lymphocytes in vivo with protein antigen entrapped in membranous vehicles

Intravenous administration of APC such as splenocytes loaded with a soluble protein Ag has been shown to prime for an Ag-specific CTL response. It is thought that the APC directly presents loaded Ag in a MHC-restricted manner. However, it is demonstrated in this study that allogeneic splenocytes, MHC-free RBC, and even synthetic lipid vesicles (liposomes) after loading with OVA can elicit an OVA-specific and MHC-restricted CTL response. Biodistribution studies of these Ag-associated vehicles showed that the liver, spleen, and lung were the major organs responsible to scavenge these carriers, suggesting that the monocyte-macrophage system was involved in the Ag presentation for CTL. Depletion of macrophages by a specific macrophage killer, Cl2MDP, containing liposomes, abolished the CTL induction by immunization with OVA Ag carried by these vehicles except the induction by syngeneic splenocytes. Thus, the syngeneic splenocytes present Ag directly to the T cells, but other membranous vehicles carry the Ag to the host APC including macrophages, which then present it to the T cells. These results indicate that formulation of an Ag in membranous/colloidal vehicles may be a way to prime for a CTL response.

In vivo cytotoxic T lymphocyte induction with soluble proteins administered in liposomes

The in vivo induction of a CTL response usually requires that Ag be endogenously synthesized so that appropriate processing can occur. In most of the few examples where successful CTL induction was reported with proteins and peptides, unacceptable adjuvants or means of Ag formulation were used. In the present report, liposomes were used to incorporate the soluble proteins OVA and beta-galactosidase. This simple and convenient to use approach, which requires minimal amounts of Ag, results in priming for a CD8+ CTL response and the establishment of immunologic memory. The liposome approach may not only prove a convenient means of inducing CTL responses in vivo but may also be useful to study the mechanisms of Ag processing.