Formation of adeno-associated virus circular genomes is differentially regulated by adenovirus E4 ORF6 and E2a gene expression

A central feature of the adeno-associated virus (AAV) latent life cycle is persistence in the form of both integrated and episomal genomes. However, the molecular processes associated with episomal long-term persistence of AAV genomes are only poorly understood. To investigate these mechanisms, we have utilized a recombinant AAV (rAAV) shuttle vector to identify circular AAV intermediates from transduced HeLa cells and primary fibroblasts. The unique structural features exhibited by these transduction intermediates included circularized monomer and dimer virus genomes in a head-to-tail array, with associated specific base pair alterations in the 5' viral D sequence. In HeLa cells, the abundance and stability of AAV circular intermediates were augmented by adenovirus expressing the E2a gene product. In the absence of E2a, adenovirus expressing the E4 open reading frame 6 gene product decreased the abundance of AAV circular intermediates, favoring instead the linear replication form monomer (Rfm) and dimer (Rfd) structures. In summary, the formation of AAV circular intermediates appears to represent a new pathway for AAV genome conversion, which is consistent with the head-to-tail concatemerization associated with latent-phase persistence of rAAV. A better understanding of this pathway may increase the utility of rAAV vectors for gene therapy.

Polarity influences the efficiency of recombinant adenoassociated virus infection in differentiated airway epithelia

To better understand mechanisms that limit rAAV transduction in the lung, we have evaluated several unique features of rAAV infection in polarized primary airway epithelial cultures. rAAV was found to transduce the basolateral surface of airway epithelia 200-fold more efficiently than the apical membrane. These differences in membrane infection correlated with the abundance of apical heparan sulfate proteoglycan (AAV-2 receptor) and virus binding. UV irradiation augmented rAAV transduction greater than 20-fold, only when virus was applied to the apical membrane. Ultrastructural analysis of UV-irradiated primary cultures demonstrated significant changes in microvilli architecture following exposure to 25 J/m2 UV. Although virus binding and the abundance of heparan sulfate proteoglycan were not increased at the apical membrane following UV irradiation, increased receptor-independent endocytosis of fluorescent beads was seen at the apical membrane following UV irradiation. We hypothesize that endocytotic processes associated with apical membrane-specific pathways of viral entry, and/or processing of virus to the nucleus, may be altered following UV irradiation. Interestingly, UV irradiation had an inhibitory effect on rAAV transduction from the basolateral membrane, which correlated with a decrease in the abundance of heparan sulfate proteoglycan at the basal membrane. In summary, these findings suggest that independent pathways of viral transduction may occur in the apical and basolateral compartments of polarized airway epithelia.

Circular intermediates of recombinant adeno-associated virus have defined structural characteristics responsible for long-term episomal persistence in muscle tissue

Adeno-associated viral (AAV) vectors have demonstrated great utility for long-term gene expression in muscle tissue. However, the mechanisms by which recombinant AAV (rAAV) genomes persist in muscle tissue remain unclear. Using a recombinant shuttle vector, we have demonstrated that circularized rAAV intermediates impart episomal persistence to rAAV genomes in muscle tissue. The majority of circular intermediates had a consistent head-to-tail configuration consisting of monomer genomes which slowly converted to large multimers of >12 kbp by 80 days postinfection. Importantly, long-term transgene expression was associated with prolonged (80-day) episomal persistence of these circular intermediates. Structural features of these circular intermediates responsible for increased persistence included a DNA element encompassing two viral inverted terminal repeats (ITRs) in a head-to-tail orientation, which confers a 10-fold increase in the stability of DNA following incorporation into plasmid-based vectors and transfection into HeLa cells. These studies suggest that certain structural characteristics of AAV circular intermediates may explain long-term episomal persistence with this vector. Such information may also aid in the development of nonviral gene delivery systems with increased efficiency.

New Carbon-Silica Composite Adsorbents from Elutrilithe

Carbon-silica composite adsorbents with high surface area and pore volume were prepared from natural elutrilithe. The elutrilithe was chemically activated with K2CO3 at 1123 K and then dissolved in water. The textural and adsorptive properties of the composite adsorbents can be adjusted by varying the pH and concentration of the sol mixture and the gel aging temperature. Composite adsorbents prepared at low concentration have high adsorption capacities for both water (43.4%) and cyclohexane (32.0%), exceeding those of ordinary commercial silica gel and active carbon. The adsorbents prepared at high concentration are more hydrophobic in nature, with adsorption capacities for water and cyclohexane of 18.5 and 41.5%, respectively. The composite adsorbents are resistant to repetitive adsorption and regeneration cycles. Copyright 1998 Academic Press.

Dual action of a ligand for Eph receptor tyrosine kinases on specific populations of axons during the development of cortical circuits

The structural basis of cortical columns are radially oriented axon collaterals that form precise connections between distinct cortical layers. During development, these connections are highly specified from the initial outgrowth of collateral branches. Our previous work provided evidence for positional cues confined to individual layers that induce and/or prevent the formation of axon collaterals in specific populations of cortical neurons. Here we demonstrated with in situ hybridization techniques that mRNA of the Eph receptor tyrosine kinase EphA5 and one of its ligands, ephrin-A5, are present in distinct cortical layers, at a time when intrinsic connections are being formed in the cortex. Axonal guidance assays indicate that ephrin-A5 is a repellent signal for a populations of axons that in vivo avoid the cortical layer expressing ephrin-A5. In contrast to its established role as a repulsive axonal guidance signal, ephrin-A5 specifically mediates sprouting of those cortical axons that target the ephrin-A5-expressing layer in vivo. These results identify a novel function of ephrin-A5 on axonal arbor formation. The laminar distribution and the dual action on specific populations of axons suggest that ephrin-A5 plays a role in the assembly of local cortical circuits.

[Pathological observation of the olfactory epithelium in dysosmia induced by chronic nasosinusitis]

OBJECTIVE

To understand the relationship between the pathology of the olfactory epithelium in dysosmia induced by nasosinusitis and the prognosis.

METHODS

The olfactory epithelium of 23 patients who had chronic nasosinusitis and undergone endoscopic sinus surgery was histologically observed. All patients were diagnosed to have anosmia by olfactory tests before the operation. The history ranged from 5 to 30 years. Fifty were males and 8 females.

RESULTS

Pathological changes were found in all cases: 16 (69.6%) with decreased olfactory cells, 10 (43.5%) had normal atrophic olfactory epithelia, 6 (26.1%) respiratory epithelial metaplasia and 10 (43.5%) mucous gland metaplasia. All the patients had been followed up for 6-10 months after operation. sixteen patients who had normal olfactory epithelia got improvement in their olfactory function; 7 patients whose olfactory epithelia were severely diseased got no amelioration of their symptoms.

CONCLUSIONS

The quantity of olfactory cells bears a positive relation with the olfactory condition.

Regulation of thalamic neurite outgrowth by the Eph ligand ephrin-A5: implications in the development of thalamocortical projections

The cerebral cortex is parcellated into different functional domains that receive distinct inputs from other cortical and subcortical regions. The molecular mechanisms underlying the specificity of connections of cortical afferents remain unclear. We report here that the Eph family tyrosine kinase receptor EphA5 and the ligand ephrin-A5 may play a key role in the exclusion of the limbic thalamic afferents from the sensorimotor cortex by mediating repulsive interactions. In situ hybridization shows that the EphA5 transcript is expressed at high levels in both cortical and subcortical limbic regions, including the frontal cortex, the subiculum, and the medial thalamic nuclei. In contrast, ephrin-A5 is transcribed abundantly in the sensorimotor cortex. Consistent with the complementary expression, the ligand inhibited dramatically the growth of neurites from neurons isolated from the medial thalamus but was permissive for the growth of neurites from lateral thalamic neurons, which is primarily nonlimbic. Similarly, the growth of neurites from Eph-A5-expressing neurons isolated from the subiculum was inhibited by ephrin-A5. Our studies suggest that the Eph family ligand ephrin-A5 serves as a general inhibitor of axonal growth from limbic neurons, which may serve to prevent innervation of inappropriate primary sensorimotor regions, thus contributing to the generation of specificity of thalamic cortical afferents.

CFTR Cl- channel and CFTR-associated ATP channel: distinct pores regulated by common gates

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that is regulated by phosphorylation of the R domain and ATP hydrolysis at two nucleotide-binding domains (NBDs). It is controversial whether CFTR conducts ATP or whether CFTR might be closely associated with a separate ATP conductance. To characterize ATP channels associated with CFTR, we analyzed Cl- and ATP single channel-currents in excised inside-out membrane patches from MDCK epithelial cells transiently expressing CFTR. With 100 mM ATP in the pipette and 140 mM Cl- in the bath, ATP channels were associated with CFTR Cl- channels in two-thirds of patches that included CFTR. CFTR Cl- channels and CFTR-associated ATP channels had slope conductances of 7.4 pS and 5.2 pS, respectively, and had distinct reversal potentials and sensitivities to channel blockers. CFTR-associated ATP channels exhibited slow gating kinetics that depended on the presence of protein kinase A and cytoplasmic ATP, similar to CFTR Cl- channels. Gating kinetics of the ATP channels as well as the CFTR Cl- channels were similarly affected by non-hydrolyzable ATP analogues and mutations in the CFTR R domain and NBDs. Our results indicate that phosphorylation- and nucleotide-hydrolysis-dependent gating of CFTR is directly involved in gating of an associated ATP channel. However, the permeation pathways for Cl- and ATP are distinct and the ATP conduction pathway is not obligatorily associated with the expression of CFTR.

1H/27Al TRAPDOR NMR studies on aluminum species in dealuminated zeolites

Aluminum species in several dealuminated zeolites (ultrastable HY, HZSM-5 and mordenite) were investigated in detail by means of the newly introduced 1H/27Al TRAPDOR method in combination with 27Al MAS NMR, and the quadrupole coupling constants (Q[CC]s) for aluminum atoms associated with these species were obtained. A signal at ca. 6.8 ppm, due to water molecules adsorbed on Lewis acid sites, was observed in the 1H MAS spectra for all the three zeolites. The TRAPDOR NMR provides direct evidence that there is a strong interaction between the adsorbed water molecules and the aluminum atoms of the Lewis-acid sites. The Q(CC) values for this aluminum species of 8.3, 6.7 and 11.3 MHz were determined from the TRAPDOR profiles for the ultrastable HY, HZSM-5 and mordenite zeolites, respectively. The Q(CC)s calculated from the TRAPDOR curves are usually larger than 10 MHz for both Bronsted-acid sites (SiOHAI) and non-framework aluminum species in the three zeolites. Three narrow peaks at 54, 30 and 0 ppm are separately superimposed on a broad hump in the 27Al MAS spectra of the three dehydrated zeolites, while the latter is associated with the 'NMR invisible' Al. The NMR experimental results suggest that the three kinds of aluminum species (non-framework aluminum species, Bronsted- and Lewis-acid sites) are all responsible for the resonance of the broad hump in dehydrated zeolites, which makes it difficult to explain the 27Al MAS spectra. Fortunately, the TRAPDOR NMR provides a direct method for individually studying different aluminum species with large Q(CC)s via their dipolar coupling to nearby proton nuclei.

Preparation and Characterization of Active Carbon Adsorbents for Wastewater Treatment from Elutrilithe

Active carbon adsorbents were prepared from natural elutrilithe by chemical activation with K2CO3. The effect of pyrolysis temperature and time and K2CO3/elutrilithe ratio on the surface area, porosity, and ash content of the adsorbents was studied. Various prior and post treatments have been tried to improve the quality of the adsorbents. An ideal active carbon adsorbent with a BET surface area of 1236 m2/g and a total pore volume of 0.679 cm3/g has been obtained. The adsorbent is hydrophobic in nature and exhibits large adsorption capacities for various phenolic compounds from aqueous solutions. Copyright 1997Academic Press

Clinical investigation of traditional Chinese medicine and pharmacy in treating respiratory tract infections in AIDS

Based on the difference in severity of the disease and complications, 80 cases of acquired immune-deficiency syndrome (AIDS) accompanied with cough were divided into 2 groups: One treated by traditional Chinese medicine (TCM group), including 58 cases and the other treated by Integrated Chinese and Western medicine (integrated group), 22 cases. The therapeutic results show that in the TCM group there were 18 cases (31.03%) with clinical cure of the respiratory tract infection, 7 cases with therapeutic effect (12.07%) and 33 cases without any effect (56.90%), for a total rate of 43.10% therapeutic effectiveness; while in the integrated group there were 6 cases with clinical cure (27.27%), 2 cases with therapeutic effect (9.09%) and 14 cases without any effect (63.64%), the total rate of therapeutic effectiveness being 36.36%, slightly lower than in the TCM group and possibly related to greater severity of the disease or complications.

Crosslinkage of collagen by polyglycidyl ethers

Calcification is the principal cause of failure of glutaraldehyde treated bioprosthetic heart valves. This article reports the crosslinkage of several polyglycidyl ethers. Calcification of yak pericardium with polyglycidyl ethers was significantly decreased compared with that crosslinked with glutaraldehyde. The process of calcification of crosslinked yak pericardium was studied using 21 day subdermal implants in rats. The uptake of calcium with ethane diglycidyl ether was reduced (0.57 +/- 0.19 vs 4.28 +/- 1.62 micrograms/mg) over that with glutaraldehyde. Four polyglycidyl ethers were developed and compared. The best compound for raising the shrinkage temperature was the shortest chain compound without steric hindrance. In the polyglycidyl ether process, a suitable amount of alcohol was necessary to promote crosslinking; the catalyst, 2, 4, 6 -tris (dimethyl aminomethyl) phenol (TDAMP) and salicylic acid, were not favorable for long-term treatment of tissues because of the unnecessarily deep dyeing of the tissue, in addition to raising the shrinkage temperature. Unlike glutaraldehyde treatment, which reacts with lysine, polyglycidyl ether treated tissues maintained flexibility of the pericardial tissue, while binding amino acids such as lysine, methionine, tyrosine, aspartic acid and glutamic acid. The authors conclude that the ethane diglycidyl ether process combined with formaldehyde would further raise the shrinkage temperature from 78 degrees C to 87.5 degrees C and sustain it above 80 degrees C. Reverse treatment was not as effective. Compared with glutaraldehyde, polyglycidyl ether treatment renders tissue more flexible, increases the thermal stability of collagen, and decreases the incidence of calcification in vivo.

[Detection of islet cell antibodies by using avidin-biotin-peroxidase complex technique]

Autoimmune mechanisms may be involved in the pathogenesis of insulin dependent diabetes mellitus (IDDM). Multiple autoantibodies have been detected in patients with IDDM. Islet cell antibodies (ICA), complent-fixing islet cell antibodies (CF-ICA) and antibodies to an islet cell protein 64000 M(r) (64K antibodies) have been regarded as immunological markers in IDDM. ICA detection with immunohistochemistry requires fresh normal human pancreas (blood group O) which provides an antigen for measuring ICA in serum samples. In the present study ICA detection was first carried out by using avidin-biotin-peroxidase complex technique (ABC) method and paraffin sections of human pancreas (blood group O), Serum samples were obtained from 17 patients with IDDM, 20 with NIDDM and 20 without diabetes mellitus. In patients with IDDM, ICA were detected in 9 of the 17 (52.94%) while none of the patients with NIDDM and without diabetes mellitus were ICA positive. In comparison with other methods, the present one is more reliable, sensitive, specific and simple. Therefore, it may be widely used for ICA detection in clinical practice.

[Epilepsy and hypohaptoglobinemia]

The serum haptoglobin (Hp) of 24 patients with familial epilepsy and 21 relatives of them, as well as 21 patients with secondary epilepsy was determined by the method of linear concentration gradient (4-22%) polyacrylamide gel electrophoresis. The mean value of their serum Hp was significantly reduced to 54.83% (P less than 0.001), 76.48% (P less than 0.01) and 74.91% (P less than 0.01) of that of the control (109.63 mgHb/dl, n = 201) respectively. The possible pathophysiological mechanism of the epileptic seizures and reduced serum Hp level was discussed briefly.

Lipogenesis stimulatory and inhibitory activities of the insulin mediators

Incubating plasma membranes prepared from pig liver with varying concentrations of insulin (50-1000 microU/ml) resulted in the release of at least two insulin chemical mediators. One of them was fraction 1 of insulin mediator (M. W. 3700-4000 daltons) which had a significant lipogenesis-stimulating activity. The other was fraction 2 of insulin mediator (M. W. about 1000 daltons) which exhibited a lipogenesis-inhibitory activity. The ratio of yield between the two mediators produced from the membranes was not only dependent on the concentration but also on the potency of insulin and its analogs added. The result showed that there was more production of fraction 2 than fraction 1 with the inducer at low concentration (100 microU/ml), while the production of fraction 1 from the plasma membranes incubated with high concentration of insulin (300 microU/ml) was higher than fraction 2. On the other hand, insulin and its analogs which have different biological activities and receptor binding activities have been used to induce the insulin mediators. The results obtained were similar to those mentioned above. This suggested that the generation of the mediators was dependent on the biological potences but not the binding activities.

Adenylate cyclase-modulating mediators of insulin

Plasma membranes prepared from pig liver incubated with insulin (50-300 microU/ml) resulted in the release of at least two insulin chemical mediators. They appeared to modulate the activity of adenylate cyclase in liver plasma membranes of pig. One of them was fraction 1 of insulin mediator (M. W. about 3700-4000 dalton) which markedly stimulated the activity of the enzyme, the other was fraction 2 of insulin mediator (M. W. about 1000 dalton) which inhibited the enzyme activity. The results showed that the inhibitor of fraction 2 generated was significantly higher than that of fraction 1 when the membranes were incubated with insulin of low concentration (50-100 microU/ml). On the other hand, the generation of stimulator of fraction 1 from plasma membranes incubated with insulin of high concentration (200 microU/ml) was higher than that of fraction 2. So the ratio of yield between two mediators produced from the membranes was dependent on the concentration of insulin added. The results also showed that the effect of fraction 1 of insulin mediator on adenylate cyclase activity in liver cell plasma membranes was biphasic while fraction 2 of insulin mediator showed an inhibitory effect only even though it was at very high concentration. The results that both mediators combined with Gpp(NH)p and forskolin to affect the enzyme activity show that the action of insulin mediators likely resides in the GTP regulatory component of adenylate cyclase.

The role of insulin mediators in regulation of cAMP and lipogenesis as well as in diabetes

Plasma membranes prepared from pig, mouse and rat liver incubated with insulin resulted in the release of at least two insulin chemical mediators. These mediators, identified as fractions 1 and 3, were found to inhibit cAMP level in response to lipolytic hormone and forskolin and to enhance lipogenesis in adipocytes of rat. Fractions 1 and 3 have been estimated to have molecular weights of 3700-4000 and 1000-1500 dalton, respectively. This initial report will focus on fraction 1. Interestingly, liver membranes from diabetic animals were found not to release mediators in the presence of insulin. However, following in vivo treatment of diabetic animals with insulin, the liver membranes appeared to restore its ability in generating chemical mediators in response to insulin.