Transdermal delivery from a lipid sponge phase--iontophoretic and passive transport in vitro of 5-aminolevulinic acid and its methyl ester

The hydrochloride salts of 5-aminolevulinic acid (ALA) and its methyl ester (m-ALA), respectively, were dissolved in a lipid sponge phase comprising monoolein, propylene glycol and aqueous buffer at concentrations of approximately 0.25% and 16% w/w m-ALA. The iontophoretic and passive delivery of ALA and m-ALA from this formulation through porcine skin in vitro were measured and compared to formulations used in clinical practice, 20% w/w ALA in Unguentum M and Metvix (a cream containing 16% w/w m-ALA). A sponge phase with 16% w/w m-ALA showed a higher passive flux (approximately 140 nmol cm(-2) h(-1) at 5 h) but a lower iontophoretic flux (approximately 800 nmol cm(-2) h(-1) at 5 h) compared to the clinically used products but the differences are hardly significant due to large standard deviations. ALA and m-ALA in sponge phase formulation showed iontophoretic fluxes in the range 80-100 nmol cm(-2) h(-1) at 3 h, i.e. values comparable to the passive fluxes from the more concentrated vehicles. The results demonstrate that the lipid sponge phase, a thermodynamically stable liquid with amphiphilic character, may have potential as a transdermal drug delivery vehicle.

Development of a closed-system process for clinical-scale generation of DCs: evaluation of two monocyte-enrichment methods and two culture containers

BACKGROUND

Clinical immunotherapy trials using DCs depend on large-scale methods for DC generation that fulfil current good manufacturing practice requirements. Our goal was to develop data on two variables, monocyte-enrichment method and culture container, which could be used to design a closed-system process for ex vivo generation of immature DCs.

METHODS

Mononuclear cells were collected by leukapheresis and enriched for monocytes by either counterflow centrifugal elutriation, or immunomagnetic selection using Isolex, an automated closed-system device. Monocytes were cultured for 7 days in serum-free medium with GM-CSF and IL-4, using either plastic flasks or gas-permeable Stericell bags. Monocytes and cultured DCs were evaluated for yield, flow cytometric phenotype, and in vitro function in MLR, and autologous recall responses to tetanus toxoid and influenza virus.

RESULTS

Enriched monocyte products from elutriation and immunomagnetic selection were equivalent in yield and purity, and were capable of generating immature DCs in either flasks or bags. DCs from all four culture conditions were equivalent in yield, phenotype, and in vitro function. Mean DC yield was 67-80% per seeding monocyte, and 11-13% per starting mononuclear cell (MNC). A leukapheresis product containing 5 x 10(9) MNCs processed by this method could therefore yield approximately 5 x 10(8) immature DCs.

DISCUSSION

In this manufacturing process, the Isolex system was equivalent to elutriation, and Stericell bags were equivalent to flasks. Together, the Isolex system and Stericell bags can be incorporated into a closed-system process to generate immature DCs.

CT and diffusion-weighted MR imaging in randomized order: diffusion-weighted imaging results in higher accuracy and lower interrater variability in the diagnosis of hyperacute ischemic stroke

BACKGROUND AND PURPOSE

Diffusion-weighted MRI (DWI) has become a commonly used imaging modality in stroke centers. The value of this method as a routine procedure is still being discussed. In previous studies, CT was always performed before DWI. Therefore, infarct progression could be a reason for the better result in DWI.

METHODS

All hyperacute (<6 hours) stroke patients admitted to our emergency department with a National Institutes of Health Stroke Scale (NIHSS) score >3 were prospectively randomized for the order in which CT and MRI were performed. Five stroke experts and 4 residents blinded to clinical data judged stroke signs and lesion size on the images. To determine the interrater variability, we calculated kappa values for both rating groups.

RESULTS

A total of 50 patients with ischemic stroke and 4 patients with transient symptoms of acute stroke (median NIHSS score, 11; range, 3 to 27) were analyzed. Of the 50 patients, 55% were examined with DWI first. The mean delay from symptom onset until CT was 180 minutes; that from symptom onset until DWI was 189 minutes. The mean delay between DWI and CT was 30 minutes. The sensitivity of infarct detection by the experts was significantly better when based on DWI (CT/DWI, 61/91%). Accuracy was 91% when based on DWI (CT, 61%). Interrater variability of lesion detection was also significantly better for DWI (CT/DWI, kappa=0.51/0.84). The assessment of lesion extent was less homogeneous on CT (CT/DWI, kappa=0.38/0.62). The differences between the 2 modalities were stronger in the residents' ratings (CT/DWI: sensitivity, 46/81%; kappa=0.38/0.76).

CONCLUSIONS

CT and DWI performed with the same delay after onset of ischemic stroke resulted in significant differences in diagnostic accuracy. DWI gives good interrater homogeneity and has a substantially better sensitivity and accuracy than CT even if the raters have limited experience.

Downregulation of beta2-microglobulin in human cord blood somatic stem cells after transplantation into livers of SCID-mice: an escape mechanism of stem cells?

Adherently growing, non-hematopoietic somatic stem cells isolated from human cord blood were stained with the fluorescent dye PKH26 and transplanted into livers of SCID-mice to examine a possible cell fate transition. Already 7 days after transplantation stem cells were well integrated into the liver tissue. Human albumin that was not expressed by the stem cells before transplantation was detectable in the host's livers after injection of cord blood stem cells. Human alpha1-antitrypsin was detectable in stem cells already before transplantation and remained positive in the mouse liver. The most interesting observation in this study was the downregulation of human beta2-microglobulin (beta2M) in the stem cells after transplantation: beta2M is expressed constitutively in our cord blood stem cells. However, beta2M was no longer detectable by RT-PCR in all tissues where human albumin and alpha1-antitrypsin were expressed after stem cell transplantation. beta2M is known to participate as an integral part of the major histocompatibility complex. Absence of beta2M makes the residual heavy chain inactive as an antigen. Thus, downregulation of beta2M may represent an escape mechanism from killer-T cells and may be a molecular mechanism explaining the recently described "immunological blindness" [37] of stem cells. In contrast to the results obtained after direct injection of stem cells as a suspension, no consistent downregulation of beta2M was observed after transplantation of stem cells encapsulated in alginate beads to generate a compartment where stem cells are protected from the host's natural killer cells. No expression of human genes was observed after transplantation of human cord blood derived mononuclear cells (MNC) that were used as a negative control. In conclusion, we have shown that human cord blood somatic stem cells survive and are reprogrammed after transplantation into mouse livers, although a complete transdifferentiation to hepatocytes did not occur within 7 days, since some marker genes (GATA4 and alpha-fetoprotein) were still negative. Switching off expression of beta2M may be part of an intriguing and novel mechanism explaining why stem cells escape the host's immune system.

Identification and characterization of Magmas, a novel mitochondria-associated protein involved in granulocyte-macrophage colony-stimulating factor signal transduction

OBJECTIVE

The aim of this study was to identify granulocyte-macrophage colony-stimulating factor (GM-CSF) responsive genes.

MATERIALS AND METHODS

Potential GM-CSF responsive genes were identified by comparing the mRNA expression pattern of the murine myeloid cell line PGMD1 grown in either interleukin-3 (IL-3) or GM-CSF by differential display. Human and murine cDNA clones of one of the bands having increased expression in GM-CSF were isolated. mRNA expression of the gene was examined by Northern blot. Immunohistochemistry and studies with a green fluorescent fusion protein were used to determine its intracellular location. Growth factor-stimulated proliferation of PGMD1 cells transfected with constitutively expressed sense and anti-sense cDNA constructs of the gene was measured by 3H-thymidine incorporation.

RESULTS

A gene, named Magmas (mitochondria-associated granulocyte macrophage CSF signaling molecule), was shown to be rapidly induced when cells were switched from IL-3 to GM-CSF. Analysis of the amino acid sequence of Magmas showed it contained a mitochondrial signal peptide, but not any other known functional domains. The human and murine clones encode nearly identical 13-kDa proteins that localized to the mitochondria. Magmas mRNA expression was observed in all tissues examined. PGMD1 cells that overexpressed Magmas proliferated similarly to untransfected cells when cultured in IL-3 or GM-CSF. In contrast, cells with reduced protein levels grew normally in IL-3, but had impaired proliferation in GM-CSF.

CONCLUSION

Magmas is a mitochondrial protein involved in GM-CSF signal transduction.

Unilateral diaphragmatic palsy in association with a subclavian vein thrombus in a very-low- birth-weight infant

Phrenic nerve paralysis due to iatrogenic injury is not uncommon in neonates. We report an unusual case of acquired unilateral paralysis of the diaphragm in a very-low-birth-weight infant, associated with a thrombus secondary to percutaneous subclavian vein catheterization. Conservative management resulted in complete resolution of the paralyzed diaphragm.

Local costimulation reinvigorates tumor-specific cytolytic T lymphocytes for experimental therapy in mice with large tumor burdens

Cytotoxic T cells recognize tumor Ags and destroy cancer cells in vitro. Adoptive transfer studies with transgenic T cells specific for tumor Ags have demonstrated that CTL are effective only in mice with small tumor burdens and thus appear to have limited potential in cancer immunotherapy. Here we used transgenic mice that express the TCR specific for an unmutated tumor Ag P1A and multiple lineages of P1A-expressing tumors to address this critical issue. We found that local costimulation, either by expression of B7-1 on the tumor cells or by local administration of anti-CD28 mAb 37N, reinvigorated the function of CTL specific for the tumor Ag, as it substantially increased the efficacy of CTL therapy for mice with large tumor burdens. Our study suggests that CTL-based immunotherapy can be manipulated to deal with large tumors.

Characterization of filter extractables by proton NMR spectroscopy: studies on intact filters with process buffers

Studies were conducted to characterize potential extractables from sterilizing grade filters. The focus of this report is the 0.22 micron Durapore (hydrophilic modified PVDF) filter which is used throughout our recovery processes. The objectives of this study are (1) to identify potential filter extractables from the hydrophilic PVDF filters; (2) to show that NMR spectroscopy may be used to detect filter extractables in the presence of product and excipients; and (3) to establish levels of filter extractables obtained by extraction with a variety of buffers. The data show that the primary source of filter extractables is the hydrophilic modification of the PVDF membrane surface. Extractables from the modified hydrophilic PVDF filter include propylene glycol (PG) and soluble oligomers of the hydroxypropyl acrylate and cross-linker. Propylene glycol, arising from the hydrolysis of the hydroxypropyl acrylate, appears to be the primary extractable in buffers above pH 11. Since the 1H-NMR method can easily detect the methyl proton signals of PG, an NMR assay was developed to detect PG in the presence of buffer excipients and final product. Propylene glycol can be used as a marker for the extractables from Durapore hydrophilic PVDF filters. Although numerous buffers were used to generate extractables from the PVDF filter, significant extractables (PG and soluble oligomers) were found only in high pH extraction buffers. As a result of this finding, only a limited number of new buffers or new PVDF filters will require testing for future validation studies. Process validation studies have shown that neither PG nor soluble oligomers are at levels that impact the quality or safety of the product.

Identification and characterization of Rhodopseudomonas spp., a purple, non-sulfur bacterium from microbial mats

A species of facultative photo-organotrophic, purple, non-sulfur bacterium was isolated from mixed-species microbial mats, characterized and examined for metal tolerance and bioremediation potential. Contributing mats were natural consortia of microbes, dominated by cyanobacteria and containing several species of bacteria arranged in a laminar structure, stabilized within a gel matrix. Constructed microbial mats were used for bioremediation of heavy metals and organic chemical pollutants. Purple, non-sulfur bacteria are characteristically found in lower strata of intact mats, but their contributing function in mats survival and function by mediating the chemical environment has not been explored. The gram-negative rod-shaped bacterium, reported here, produced a dark red culture under phototrophic conditions, reproduced by budding and formed a lamellar intracytoplasmic membrane (ICM) system parallel to cytoplasmic membrane, which contained bacteriochlorophyll a and carotenoids. This strain was found to have multiple metal resistances and to be effective in the reductive removal of Cr(VI) and the degradation of 2,4,6-trichlorophenol. Based on the results obtained from morphology, nutrient requirements, major bacteriochlorophyll content, GC content, random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) profile and 16S-rDNA phylogenetic analysis, this member of the microbial mats may be identified as a new strain of the genus Rhodopseudomonas.

Filter extrusion of liposomes using different devices: comparison of liposome size, encapsulation efficiency, and process characteristics

Liposomes were prepared by stepwise extrusion through 5, 1, 0.4, 0.2, 0.1 and 0.05 microm pore sizes using two different filter-extruders, the continuous high pressure device Dispex Maximator (CE) or alternatively the discontinuous Avestin LiposoFast (DE). The liposome dispersions obtained were compared in terms of particle size, lamellarity and encapsulation efficiency of calcein. The liposomes were smaller with CE than DE at all stages due to higher flow rates and pressure drops, except for final filter pore size (0.05 microm) where both preparations had similar sizes. The particle size analysis technique itself had a strong influence on the liposome sizes measured. For bigger liposomes (extruded through 0.4 microm filters) the Nicomp 370 revealed bigger volume-based mean particle sizes along with more stringent differences between volume-based and number-based diameters than the Malvern Zetasizer. In contrast, for small liposomes extruded through 0.05 microm filters, similar liposome sizes were found no matter which of the two PCS techniques or cryo-transmission electron microscopy was used. In congruence to the liposome sizes measured, encapsulation efficiencies were smaller for CE than DE at all filter stages except the final (0.05 microm). No lipid loss occurred and lyso-phosphatidylcholine formation was negligible irrespective of which extrusion technique was used.

Arabidopsis cmt3 chromomethylase mutations block non-CG methylation and silencing of an endogenous gene

Plants maintain cytosine methylation at CG and non-CG residues to control gene expression and genome stability. In a screen for Arabidopsis mutants that alter methylation and silencing of a densely methylated endogenous reporter gene, we recovered 11 loss-of-function alleles in the CMT3 chromomethylase gene. The cmt3 mutants displayed enhanced expression and reduced methylation of the reporter, particularly at non-CG cytosines. CNG methylation was also reduced at repetitive centromeric sequences. Thus, CMT3 is a key determinant for non-CG methylation. The lack of CMT homologs in animal genomes could account for the observation that in contrast to plants, animals maintain primarily CG methylation.

Two Arabidopsis methylation-deficiency mutations confer only partial effects on a methylated endogenous gene family

In Arabidopsis a SWI2/SNF2 chromatin remodeling factor-related protein DDM1 and a cytosine methyltransferase MET1 are required for maintenance of genomic cytosine methylation. Mutations in either gene cause global demethylation. In this work we have assessed the effects of these mutations on the PAI tryptophan biosynthetic gene family, which consists of four densely methylated genes arranged as a tail-to-tail inverted repeat plus two unlinked singlet genes. The methylation mutations caused only partial demethylation of the PAI loci: ddm1 had a strong effect on the singlet genes but a weaker effect on the inverted repeat, whereas met1 had a stronger effect on the inverted repeat than on the singlet genes. The double ddm1 met1 mutant also displayed partial demethylation of the PAI genes, with a pattern similar to the ddm1 single mutant. To determine the relationship between partial methylation and expression for the singlet PAI2 gene we constructed a novel reporter strain of Arabidopsis in which PAI2 silencing could be monitored by a blue fluorescent plant phenotype diagnostic of tryptophan pathway defects. This reporter strain revealed that intermediate levels of methylation correlate with intermediate suppression of the fluorescent phenotype.

Klinisch stumme Hirnembolien nach zerebraler Katheterangiographie

PURPOSE

To assess for the incidence of clinically silent cerebral lesions after cerebral catheter angiography.

METHODS

MRI including PD-, T2-, and diffusion-weighted images was performed shortly before and after 27 cerebral catheter angiographies.

RESULTS

After 5/27 angiographies (18.5%) we found 6 new, presumably embolic cerebral lesions with a typical diameter of 2-3 mm on diffusion-weighted images. No correlation was found between the occurrence of these lesions and a preexisting arteriosclerotic cerebrovascular disease, fluoroscopy time, or number of angiographic series.

CONCLUSION

Cerebral angiography appears to be associated with a relatively high risk (about 20%) of clinically silent cerebral embolism. This risk is higher than has been estimated based on the incidence of neurological deficits (0.1-0.3%) after cerebral angiography. The safety of cerebral angiography needs to be improved. Diffusion-weighted MR imaging is suitable to monitor the safety of angiographic procedures and material.

A new flux-orientated concept to derive critical levels for ozone to protect vegetation

The current European critical levels for ozone (O3) to protect crops, natural and semi-natural vegetation and forest trees are based on a relative small number of open-top chamber experiments with a very limited number of plant species. Therefore, the working group "Effects of Ozone on Plants" of the Commission on Air Pollution Prevention of the Association of German Engineers and the German Institute of Standardization reanalysed the literature on O3 effects on European plant species published between 1989 and 1999. An exposure-response relationship for wild plant species and agricultural crops could be derived from 30 experiments with more than 30 species and 90 data points; the relationship for conifer and deciduous trees is based on 20 experiments with nine species and 50 data points. From these relationships maximum O3 concentrations for different risk stages are deduced, below which the vegetation type is protected on the basis of the respective criteria. Because it is assumed that the fumigation concentrations reflect the O3 concentrations at the top of the canopy, i.e. the upper surface boundary of the quasi-laminar layer if the micrometeorological big-leaf approach is applied, the application of these maximum O3 concentrations requires the transformation of O3 concentrations measured at a reference height above the canopy to the effective phytotoxic concentrations at the top of the canopy. Thus, the approach described in this paper is a synthesis of the classical concept of toxicology of air pollutants (critical concentrations) and the more toxicological relevant dose concept.

Metabolism and pharmacokinetics of N1,N11-diethylnorspermine in a Cebus apella primate model

The tissue distribution, metabolic profile, and pharmacokinetic parameters of i.v.-administered N1,N11-diethylnorspermine (DENSPM) are evaluated in Cebus apella primates, and the results are compared with data gathered from canine and human studies. Although the metabolic processing of DENSPM (i.e., deethylation and deaminopropylation) in dogs and primates is very similar, there are some significant differences in tissue distribution of the parent drug. In dogs, the organ concentration of DENSPM follows the order kidney >> liver approximately = lung > spleen. In the primate, the order is liver >> kidney approximately = spleen > lung. The difference in pharmacokinetic parameters between the species is profound with (area under the time-concentration curve)primate << (area under the time-concentration curve)dog; (terminal elimination half-life)primate << (terminal elimination half-life)dog; and (mean residence time)primate << (mean residence time)dog. The most notable difference between dogs and primates is seen in the fraction of parent drug excreted unchanged in the urine, 50% in the dog and < 1% in the primate. However, the pharmacokinetic parameters and urinary drug clearance in C. apella primates are remarkably similar to those in humans. Thus, C. apella is established as an excellent model for assessing the metabolism, tissue distribution, and pharmacokinetic properties of polyamine analogues.

Homeostasis of alpha beta TCR+ T cells

Cytokines contribute to T cell homeostasis at all stages of T cell existence. However, the particular cytokine involved varies as T cells progress from a naïve through an activated to a memory state. In many cases the important cytokines are members of the interleukin 2 subfamily of the short-chain type I cytokines. A case is made for the idea that the evolutionary divergence of the short-chain family allowed for concurrent divergence in leukocytes.