Use of Anti-Glycopeptidolipid-Core Antibodies Serology for Diagnosis and Monitoring of Mycobacterium avium Complex Pulmonary Disease in the United States

Background

There is an unmet need for rapid, accurate, and noninvasive assays for diagnosis and monitoring of Mycobacterium avium complex pulmonary disease (MAC-PD). We evaluated the diagnostic accuracy of an anti-glycopeptidolipid (GPL)-core immunoglobulin A (IgA) antibody test in a US cohort of MAC patients, and we described serial serology changes during antimicrobial therapy.

Methods

We identified serum samples from MAC patients starting treatment at enrollment and control subjects with or without bronchiectasis within OHSU's NTM Biobank. We conducted diagnostic test accuracy. Changes in mean levels of anti-GPL-core IgA antibodies between 0 and 3, 6, or 12 months after treatment start were assessed using the Student's paired t test. Pearson's correlation coefficient was calculated for IgA antibody levels and Student paired t test measures.

Results

We included 25 MAC patients and 18 controls. At baseline, IgA antibody concentrations in MAC patients (3.40 ± 6.77 U/mL) were significantly higher than in controls without bronchiectasis (0.14 ± 0.03 U/mL, P = .02). Sensitivity and specificity for MAC-PD in this population was 48% and 89% (cutoff point 0.7 U/mL), respectively. Among MAC patients starting antimicrobial therapy, mean IgA levels decreased 0.3202 U/mL (P = .86) at month 3, 0.8678 U/mL (P = .47) at month 6, and 1.9816 U/mL (P = .41) at 1 year. Quality of Life-Bronchiectasis Respiratory Symptom Scale improvement correlated with decreasing IgA titers after 12 months of treatment in MAC patients (r = −0.50, P = .06).

Conclusions

Anti-GPL-core IgA antibody levels are relatively specific for MAC-PD and decrease with treatment. Larger studies are warranted to evaluate the role of IgA serology in monitoring treatment response or for disease relapse/reinfection.

Pressure-induced stacking disorder in boehmite

The structure of an aluminum layered hydroxide, boehmite (γ-AlOOH), as a function of pressure was studied by using in situ synchrotron X-ray and neutron diffraction. Peak broadening, which is only found for hkl (h ≠ 0) peaks in the X-ray diffraction patterns, is explained by stacking disorder accompanying a continuously increasing displacement of the AlO6 octahedral layer along the a-axis. This finding could be the first experimental result for pressure-induced stacking disorder driven by continuous layer displacement. The magnitude of the layer displacement was estimated from the X-ray scattering profile calculation based on the stacking disordered structure model. Hydrogen bond geometries of boehmite, obtained by structure refinements of the observed neutron diffraction patterns for the deuterated sample up to 10 GPa, show linearly approaching O-D covalent and DO hydrogen bond distances and they merge below 26 GPa. Pressure-induced stacking disorder makes the electrostatic potential of hydrogen bonds asymmetric, yielding less chance for proton-tunnelling.

Ice VII from aqueous salt solutions: From a glass to a crystal with broken H-bonds

It has been known for decades that certain aqueous salt solutions of LiCl and LiBr readily form glasses when cooled to below ≈160 K. This fact has recently been exploited to produce a « salty » high-pressure ice form: When the glass is compressed at low temperatures to pressures higher than 4 GPa and subsequently warmed, it crystallizes into ice VII with the ionic species trapped inside the ice lattice. Here we report the extreme limit of salt incorporation into ice VII, using high pressure neutron diffraction and molecular dynamics simulations. We show that high-pressure crystallisation of aqueous solutions of LiCl∙RH₂O and LiBr∙RH₂O with R = 5.6 leads to solids with strongly expanded volume, a destruction of the hydrogen-bond network with an isotropic distribution of water-dipole moments, as well as a crystal-to-amorphous transition on decompression. This highly unusual behaviour constitutes an interesting pathway from a glass to a crystal where translational periodicity is restored but the rotational degrees of freedom remaining completely random.

Partially ordered state of ice XV

Most ice polymorphs have order-disorder "pairs" in terms of hydrogen positions, which contributes to the rich variety of ice polymorphs; in fact, three recently discovered polymorphs- ices XIII, XIV, and XV-are ordered counter forms to already identified disordered phases. Despite the considerable effort to understand order-disorder transition in ice crystals, there is an inconsistency among the various experiments and calculations for ice XV, the ordered counter form of ice VI, i.e., neutron diffraction observations suggest antiferroelectrically ordered structures, which disagree with dielectric measurement and theoretical studies, implying ferroelectrically ordered structures. Here we investigate in-situ neutron diffraction measurements and density functional theory calculations to revisit the structure and stability of ice XV. We find that none of the completely ordered configurations are particular favored; instead, partially ordered states are established as a mixture of ordered domains in disordered ice VI. This scenario in which several kinds of ordered configuration coexist dispels the contradictions in previous studies. It means that the order-disorder pairs in ice polymorphs are not one-to-one correspondent pairs but rather have one-to-n correspondence, where there are n possible configurations at finite temperature.

The structure of CO₂ hydrate between 0.7 and 1.0 GPa

A deuterated sample of CO2 structure I (sI) clathrate hydrate (CO2·8.3 D2O) has been formed and neutron diffraction experiments up to 1.0 GPa at 240 K were performed. The sI CO2 hydrate transformed at 0.7 GPa into the high pressure phase that had been observed previously by Hirai et al. [J. Phys. Chem. 133, 124511 (2010)] and Bollengier et al. [Geochim. Cosmochim. Acta 119, 322 (2013)], but which had not been structurally identified. The current neutron diffraction data were successfully fitted to a filled ice structure with CO2 molecules filling the water channels. This CO2+water system has also been investigated using classical molecular dynamics and density functional ab initio methods to provide additional characterization of the high pressure structure. Both models indicate the water network adapts a MH-III "like" filled ice structure with considerable disorder of the orientations of the CO2 molecule. Furthermore, the disorder appears to be a direct result of the level of proton disorder in the water network. In contrast to the conclusions of Bollengier et al., our neutron diffraction data show that the filled ice phase can be recovered to ambient pressure (0.1 MPa) at 96 K, and recrystallization to sI hydrate occurs upon subsequent heating to 150 K, possibly by first forming low density amorphous ice. Unlike other clathrate hydrate systems, which transform from the sI or sII structure to the hexagonal structure (sH) then to the filled ice structure, CO2 hydrate transforms directly from the sI form to the filled ice structure.

Interleukin-6-induced satellite cell proliferation is regulated by induction of the JAK2/STAT3 signalling pathway through cyclin D1 targeting

OBJECTIVES

To determine whether interleukin-6 (IL-6) stimulates rat muscle satellite cell proliferation in culture, and if so, to clarify the signalling mechanisms.

MATERIALS AND METHODS

Primary satellite cells were isolated from thirty male F344 rats, 11 weeks of age. IL-6 at concentrations of 0.01, 0.1, 1, 10 or 100 ng/ml was added to culture media.

RESULTS

IL-6 at 0.01-1 ng/ml induced dose-dependent increase in cell proliferation. After treatment with 1 ng/ml IL-6, cell proliferation increased by 31%, and p-STAT3(+) /MyoD(+) cells increased in number compared to those in control media (P < 0.05). Inhibitors of JAK2 (AG 490) and STAT3 (STAT3 peptide) blocked the increase in BrdUrd(+) cell numbers at 6 h post stimulation with 1 ng/ml IL-6 (P < 0.05). Furthermore, cyclin D1 mRNA expression and cyclin D1(+) /MyoD(+) cell numbers significantly increased in cultures treated with 1 ng/ml IL-6 compared to those in control media (P < 0.05). In contrast, treatment with 10 and 100 ng/ml IL-6 did not stimulate cell proliferation. Treatment with 10 ng/ml IL-6 induced greater SOCS3 mRNA expression than with 1 ng/ml IL-6 and control media. Moreover, co-localization of SOCS3 and myogenin was observed after treatment with 10 ng/ml IL-6.

CONCLUSIONS

IL-6 induced dose-dependent increase in satellite cell proliferation by activating the JAK2/STAT3/cyclin D1 pathway.

Satellite cell pool enhancement in rat plantaris muscle by endurance training depends on intensity rather than duration

AIM

Increases in the number of satellite cells are necessary for the maintenance of normal muscle function. Endurance training enhances the satellite cell pool. However, it remains unclear whether exercise intensity or exercise duration is more important to enhance the satellite cell pool. This study examined the effects of different intensity and duration of endurance training on the satellite cell pool in rat skeletal muscle.

METHODS

Forty-one 17-week-old female Sprague-Dawley rats were assigned to control (n = 8), high intensity and high duration (n = 7), high intensity and low duration (n = 8), low intensity and high duration (n = 9) and low intensity and low duration (n = 9) groups. Training groups exercised 5 days per week on a motor driven treadmill for 10 weeks. After the training period, animals were anaesthetized and the plantaris muscles were removed, weighed and analysed for immunohistochemical and histochemical properties.

RESULTS

Although no significant differences were found in muscle mass, mean fibre area and myonuclei per muscle fibre between all groups, the percentage of satellite cells was significantly higher in the high-intensity groups than in the other groups (P < 0.05).

CONCLUSION

Increases in the satellite cell pool of skeletal muscle following endurance training depend on the intensity rather than duration of exercise.

Cytochrome P450 genetic polymorphisms influence the serum concentration of calcineurin inhibitors in allogeneic hematopoietic SCT recipients

Calcineurin inhibitors are necessary as immunosuppressants during hematopoietic SCT (HSCT) to prevent alloreactivity, but have unfortunate toxicities. So, we investigated the association of gene polymorphisms with the initial calcineurin inhibitor concentration and the subsequent drug dose from day 1 to day 28 among patients who underwent HSCT at a single institution. We analyzed 58 serial cases of Japanese patients receiving GVHD prophylaxis with CsA (21 cases) or tacrolimus (37 cases). We investigated eight single-nucleotide polymorphisms: rs4244285 (CYP2C19), rs15524, rs4646450, rs3800959, rs776746 (CYP3A5), rs1128503, rs2032582 and rs1045642 (MDR1). The CsA concentration was significantly higher when the genotype of CYP3A5 rs15524 was T/T (P=0.044) or rs776746 was G/G (P=0.027). The CYP3A5 rs776746 and rs4646450 genotypes were also associated with tacrolimus concentration (P=0.013 and P=0.0058, respectively). The dosage of tacrolimus was remarkably reduced from day -1 to day 28 when the patient had the CYP3A5 rs4646450 C/C and/or rs776746 G/G genotype (P=0.0010 and P=0.0021, respectively). In this study, we show that genetic variation has a predictable effect on the pharmacological responses to calcineurin inhibitors in HSCT patients.

Sensitivity and specificity of photopic negative response of focal electoretinogram to detect glaucomatous eyes

AIMS

To determine the sensitivity and specificity of the photopic negative response (PhNR) of the focal electroretinograms (ERG; focal PhNR) to detect glaucomatous eyes with different degrees of visual field defects.

METHODS

One-hundred and fourteen eyes of 114 patients with open angle glaucoma and 42 eyes of 42 normal controls were studied. The focal ERGs were elicited by a 15 degrees stimulus spot centred on the macula, and on the supero-temporal and on the infero-temporal areas of the macula. The receiver operating characteristic curves were determined to obtain optimal cut-off values. Eyes were classified as being glaucomatous when their focal PhNRs were less than the cut-off values in either retinal area (combined criterion).

RESULTS

The focal PhNR amplitudes were significantly reduced with an advance in the stage of glaucoma. In early glaucoma, the sensitivities of the PhNR measured for each retinal area ranged from 58.1% to 80.7%. The sensitivities were significantly increased to 90.6% and 96.9% for the focal PhNR amplitude and the focal PhNR/b-wave amplitude ratio, respectively, when the combined criterion was employed. The specificity was >90%.

CONCLUSIONS

Focal PhNRs have diagnostic ability in detecting early glaucoma with high sensitivity and specificity, especially when the combined criterion is used.

Minimum stable structure of the receptor for advanced glycation end product possesses multi ligand binding ability

The receptor for advanced glycation end products (RAGE) is a multi-ligand receptor involved in the development of diabetic complications. Although the soluble form of the extracellular domain maintains the ability to bind multi-ligands, it is unstable and degrades into several peptide species during storage. Proteolysis with thrombin or factor Xa revealed several protease sensitive sites. Most sensitive site is located between Arg228 and Val229, and peptide bond next to Arg216, Arg116, Arg114 and Trp271 are also cleaved. Seven truncated extracellular domains of RAGE were engineered in order to obtain a stable soluble fragment. RAGE 143 (Ala23-Thr143) is not only protease resistant but also shows the same ligand-binding ability as that of the full-length extracellular domain. The resultant minimum RAGE 143 works as a stable recognition devise to detect advanced glycation end products (AGEs).

Response of a Strand to Axial and Torsional Displacements

Taking advantage of geometric considerations the authors give explicit expressions for the determination of axial force, bending and twisting moments in the helical wires, and for the axial force and twisting moment in the core of a 7-wire strand subjected to axial and torsional displacements. The equations given are linear, could be similarly developed for strands of any number of wires or for strands subjected to large displacements, and should be found practical by designers. Measurements on oversize epoxy models of the strand show good correlation with the theory and support the observation that axial load has no effect on the effective torsional rigidity of the strand. Results of experimental strain analyses on steel strands and on models of strands, as well as other theoretical studies on helices and strands, will be published in other papers.

Changes in signalling molecule levels in 10-day hindlimb immobilized rat muscles

AIM

Hindlimb immobilization produces similar percentage decreases in muscle mass in the predominantly type I soleus and type II vastus lateralis muscles. Consequently we hypothesized that the percentage changes in potential regulatory molecules for atrophy would be similar in the two muscle fibre types.

METHODS

Therefore, the purpose of the current study was to measure phosphorylated p38 MAPK and JNK, as well as the protein levels of p53, growth arrest and DNA damage-inducible 45 (GADD45), and full-length poly(ADP-ribose) polymerase (PARP) to determine whether their changes in expression in the soleus and vastus lateralis muscles were similar at 10th day of hindlimb immobilization in young rats.

RESULTS

Unexpectedly, preferential increases in phosphorylation of p38 MAPK and JNK and in the protein levels of p53, GADD45, as well as decreases in full-length PARP occurred in the soleus muscle, while only p38 phosphorylation increased in the white portion of the vastus lateralis muscle at 10th day of hindlimb immobilization.

CONCLUSION

Taken together, these results are interpreted to suggest that some of regulatory processes or kinetics in the atrophy of type I and II muscle fibres during limb immobilization may differ at the 10th day of limb immobilization.

Primary rat muscle progenitor cells have decreased proliferation and myotube formation during passages

Adult skeletal muscle contains populations of satellite cells and muscle-derived stem cells that are capable of forming multinucleate myotubes. The purpose of this study was to determine the phenotype of cells isolated from a common satellite cell isolation and passaging procedure from whole skeletal muscle. To ascertain the characteristics of the cellular phenotype, the myogenic markers MyoD and desmin, the satellite-cell-specific marker Pax7, and the haemopoietic stem cell markers CD34 and CD45 were examined by immunohistochemical analysis. Immediately after isolation, > 90% myogenic marker-positive cells were positive for desmin, MyoD and Pax7. In contrast, approximately 10% of the isolated cells expressed only CD34 or CD45. After three passages, the percentage of cells that were positive for the myogenic markers desmin, MyoD and Pax7 was reduced to approximately 55%, while the population of CD34- or CD45-positive cells increased to approximately 30% after the third passage. Immunohistochemical detection of bromodeoxyuridine demonstrated that the number of proliferating cells decreased progressively after each passaging. Finally, after the third passage the percentage of nuclei in myotubes decreased from 46.7% to 12.5%. Since passaging of muscle progenitor cells is common practice, the results of the current report suggest that characterization of cell heterogeneity needs to be made frequently.

Prediction of ovarian reserve based on day-3 serum follicle stimulating hormone concentrations during the pituitary suppression cycle using a gonadotropin releasing hormone agonist in patients undergoing in vitro fertilization-embryo transfer

Satisfactory results following in vitro fertilization-embryo transfer (IVF-ET) treatments depend on retrieving an appropriate number of mature oocytes without causing the development of ovarian hyperstimulation syndrome (OHSS). The present study was carried out to investigate whether the ovarian reserve is predictable based on the day-3 serum concentration of follicle stimulating hormone (FSH) during the pituitary suppression cycle using a gonadotropin releasing hormone (GnRH) agonist (defined as day-3 FSH) in patients undergoing IVF-ET treatment. Day-3 FSH before the administration of gonadotropin was assessed in 72 IVF-ET cycles from 59 infertile women. The mean+/-SD of day-3 FSH, the total amount of FSH plus human menopausal gonadotropin (hMG) administered, and the total number of oocytes retrieved was 5.5+/-2.6 mIU/ml, 2834.2+/-1236.5 IU and 7.7+/-5.8, respectively. There were significant correlations between day-3 FSH and the total amount of FSH-hMG administered (p < 0.001), and day-3 FSH and total number of oocytes retrieved (p < 0.001). There was a significant difference of day-3 FSH between patients who subsequently conceived (4.4+/-1.3 mIU/ml) and those who did not conceive (6.1+/-2.9 mIU/ml) (p = 0.001). There was also a significant difference of day-3 FSH between patients who developed moderate or severe OHSS (4.5+/-1.2 mIU/ml) and those who did not (5.9+/-2.8 mIU/ml) (p = 0.003). Receiver-operator characteristic curve analysis showed that the significant cut-off point for day-3 FSH for predicting ovarian reserve was 5.25 mIU/ml. These findings indicate that day 3-FSH is usefulfor predicting ovarian reserve during the pituitary suppression cycle using a GnRH agonist in patients undergoing IVF-ET.

Overexpression and protein folding of a chimeric beta-glucosidase constructed from Agrobacterium tumefaciens and Cellvibrio gilvus

In continuation of our investigation on structure and function relationship of beta-glucosidases from mesophilic and thermophilic bacteria, we constructed a chimeric gene by shuffling 17% length in C terminal region of beta-glucosidase of Agrobacterium tumefaciens with the corresponding homologous region of Cellvibrio gilvus beta-glucosidase. The chimeric gene was overexpressed in E. coli BL21 (DE3) using pET vector. However, nearly all of the beta-glucosidase produced was trapped into inclusion bodies in catalytically non-functional state. Attempts were made to solubilize the overexpressed protein by co-expression with molecular chaperone, GroEL/ES, in vivo. The molecular chaperone assisted protein folding that had earlier yielded encouraging results, did not improve the solubilization in the present case with a chimeric beta-glucosidase. Further, we explored protein renaturation under in vitro conditions using various dialysis strategies. Dialysis, rapid dilution and a newly devised method of folding immobilized proteins yielded active enzyme. The usefulness of the in vitro folding methods to obtain functional enzymes from overproduced but non-functional proteins has been discussed.

Interaction of SMKT, a killer toxin produced by Pichia farinosa, with the yeast cell membranes

SMKT (salt-mediated killer toxin), a killer toxin produced by the halotolerant yeast, Pichia farinosa, kills yeasts of several genera, including Saccharomyces cerevisiae. To elucidate the killing mechanism of SMKT, we examined the interaction of SMKT with membranes using liposomes. Leakage of calcein from calcein-entrapped liposomes was observed in the presence of SMKT. Destruction of liposomes was observed by dark-field microscopy. Comparison of intact S. cerevisiae cells with SMKT-treated cells by dark-field microscopy indicated that the spherical cell membrane is disrupted by SMKT. Using sodium carbonate extraction, we obtained direct evidence for the first time that SMKT is associated with the membrane of sensitive cells. Our results indicate that SMKT kills sensitive S. cerevisiae by interacting with the yeast cell membrane.

Involvement of conserved hydrophobic residues in the CTLD of human lectin-like oxidized LDL receptor in ligand binding

We previously identified the hydrophilic residues that are essential for ligand binding in the C-type lectin-like domain (CTLD) of human lectin-like oxidized LDL receptor (hLOX-1). To provide a more detailed understanding of ligand binding, we selected in the present study 13 conserved hydrophobic residues in the CTLD of hLOX-1 for mutagenesis analysis. The selected residues were replaced either by Ser (drastic mutation) or by size- and structure-based alternative hydrophobic residues (conserved mutation). Mutation targeted at F228, Y238, and G232 deprived hLOX-1 of ligand binding without alteration of protein expression and localization. In contrast, drastic mutation introduced into positions W203, W215, and W217 resulted in mislocalization, whereas conserved mutation at the same sites resulted in clones with similar cell surface localization and ligand binding to native hLOX-1. Our results indicate that F228, Y238, and G232 are essential for ligand binding, while W203, W215, W217, and L206 play a structural role.

Constitutive "light" adaptation in rods from G90D rhodopsin: a mechanism for human congenital nightblindness without rod cell loss

A dominant form of human congenital nightblindness is caused by a gly90-->asp (G90D) mutation in rhodopsin. G90D has been shown to activate the phototransduction cascade in the absence of light in vitro. Such constitutive activity of G90D rhodopsin in vivo would desensitize rod photoreceptors and lead to nightblindness. In contrast, other rhodopsin mutations typically give rise to nightblindness by causing rod cell death. Thus, the proposed desensitization without rod degeneration would be a novel mechanism for this disorder. To explore this possibility, we induced mice to express G90D opsin in their rods and then examined rod function and morphology, after first crossing the transgenic animals with rhodopsin knock-out mice to obtain appropriate levels of opsin expression. The G90D mouse opsin bound the chromophore and formed a bleachable visual pigment with lambda(max) of 492 nm that supported rod photoresponses. (G+/-, R+/-) retinas, heterozygous for both G90D and wild-type (WT) rhodopsin, possessed normal numbers of photoreceptors and had a normal rhodopsin complement but exhibited considerable loss of rod sensitivity as measured electroretinographically. The rod photoresponses were desensitized, and the response time to peak was faster than in (R+/-) animals. An equivalent desensitization resulted by exposing WT retinas to a background light producing 82 photoisomerizations rod(-1) sec(-1), suggesting that G90D rods in darkness act as if they are partially "light-adapted." Adding a second G90D allele gave (G+/+, R+/-) animals that exhibited a further increase of equivalent background light level but had no rod cell loss by 24 weeks of age. (G+/+, R-/-) retinas that express only the mutant rhodopsin develop normal rod outer segments and show minimal rod cell loss even at 1 year of age. We conclude that G90D is constitutively active in mouse rods in vivo but that it does not cause significant rod degeneration. Instead, G90D desensitizes rods by a process equivalent to light adaptation.

Introduction of tapasin gene restores surface expression of HLA class I molecules, but not antigen presentation of an HIV envelope peptide in a hepatoma cell line

A hepatoma cell line, Hep G2, reveals the diminished HLA class I surface expression and the reduced expression of LMP2, LMP7, and tapasin transcripts, suggesting that the reduced expression of these transcripts may be associated with the low expression of HLA class I molecules. Introduction of tapasin gene dramatically up-regulates the surface expression of HLA class I molecules on Hep G2 cells, and unexpectedly, enhances the expression of LMP2 and LMP7 transcripts as well. Unlike Hep G2, these tapasin-transfected Hep G2 cells are recognized by allo-specific CTL. However, the transfectant is unable to endogenously present an HIV envelope peptide to an HIV-specific CTL clone, suggesting that a proteasome-independent antigen processing pathway exists and still remains defective in the transfectant. These data may provide significant evidence that the nonproteasomal antigen processing pathway as well as the proteasomal pathway may be impaired in tumor cells to escape immune surveillance performed by CTL.

Atypical membranoproliferative glomerulonephritis in a cat

Membranoproliferative glomerulonephritis was observed in a 2-year-old male Japanese domestic cat with clinical renal failure. In the glomeruli, moderate mesangial hypercellularity with an increased mesangial matrix and thickening of the capillary walls were prominent. In addition, frequent duplication of the capillary walls, splitting, and spike formation were observed in the glomerular basement membrane. Granular cat IgG and complement component deposition were detected globally along the glomerular capillary walls and in the mesangium. Transmission electron microscopy revealed dense deposits in the subendothelial and subepithelial regions and the mesangium. Mesangial interposition was also observed. These glomerular lesions are also found in humans with membranoproliferative glomerulonephritis type III, which has not been reported in animals.

Comparative structural and functional analysis of photoreceptor neurons of Rho-/- mice reveal increased survival on C57BL/6J in comparison to 129Sv genetic background

To explore the possible influence of defined genetic backgrounds on photoreceptor viability and function in mice carrying a targeted disruption of the rhodopsin gene, the severities of retinopathies in Rho-/- mice on C57BL/6J and 129Sv congenic backgrounds were compared by light microscopy and electroretinography and qualitatively by in situ end labeling of DNA in apoptotic photoreceptor nuclei of retinal sections. Cone photoreceptor viability and function were shown to deteriorate more slowly on the C57BL/6J background in comparison to that of the 129Sv, with significantly greater numbers of outer nuclear layer nuclei in the retinas of C57BL/6J mice at 3 and 4 months of age. Both amplitude and waveform features of the ERG were shown to be remarkably different in the two strains, indicating an approximately 6-fold difference in C57BL/6J Rho-/- mice compared to 129Sv Rho-/- mice at 80 days. Thus, in comparison with the 129Sv strain, genetic modifiers appear to constitute a component of the C57BL/6J background, the expression of which significantly protects cone photoreceptors from apoptotic death in a mutation-induced murine retinopathy. The differences in phenotype revealed in this study are sufficient in principle to provide a basis for comparisons to be made between QTLs in light-induced and mutation-induced systems.

Lens epithelium-derived growth factor promotes photoreceptor survival in light-damaged and RCS rats

PURPOSE

To investigate possible protective effects of lens epithelium-derived growth factor (LEDGF) against photoreceptor death in light-damaged, Royal College of Surgeons (RCS) and P23H rhodopsin transgenic rats.

METHODS

Twelve-week-old Sprague-Dawley (SD), 6-week-old RCS, and 10-day-old P23H (line 1, heterozygote) rats received an intravitreal injection of LEDGF fused with glutathione-S-transferase (GST-LEDGF). Fellow eyes received vehicle and served as control specimens. Two days after the injections, the SD rats were exposed to light of 2000 lux for 48 hours. Corneal Ganzfeld ERGs were recorded 10 days after light damage, at 10 weeks of age in RCS rats, and at 4 weeks of age in P23H rats. The eyes were then processed for histologic analysis. Heat shock protein (hsp) content in the sensory retina was analyzed quantitatively by protein immunoblot.

RESULTS

In light-damaged rats, the ERG indicated retinal protection in GST-LEDGF-injected eyes, with b-wave and STR thresholds being 1.14 +/- 0.50 (mean +/- SD) and 0.60 +/- 0.26 log candela (cd)/m2 lower, respectively, than in vehicle-injected eyes (P < 0.01). The GST-LEDGF-treated eyes had maximum b-wave amplitudes that were significantly larger (P < 0.0005), had more than twice as many remaining photoreceptors, and had better organized outer segments than the control eyes. In RCS rats, the treated eyes had 2.76 +/- 0.73 and 0.83 +/- 0.09 log cd/m(2) lower thresholds for the b-wave and STR, respectively (P < 0.005), and had significantly larger maximum b-wave amplitude (P < 0.0005). GST-LEDGF-treated eyes of RCS rats also had more photoreceptors remaining (P < 0.005) and a thinner debris layer than control eyes. In P23H rats, GST-LEDGF treatment did not protect either retinal function or structure. The retinas from GST-LEDGF-treated eyes of SD and RCS rats had higher levels of hsp25 and alphaB-crystallin than vehicle-injected eyes.

CONCLUSIONS

GST-LEDGF protects photoreceptor structure and function in both light-damaged and RCS rats. The increased expression of hsp25 and alphaB-crystallin may play a role in this protection. The absence of rescue in P23H raises the possibility that some forms of inherited retinal degeneration may not be amenable to treatment by intraocular injection of LEDGF.

Characterization of residues and sequences of the carbohydrate recognition domain required for cell surface localization and ligand binding of human lectin-like oxidized LDL receptor

Lectin-like oxidized low-density lipoprotein receptor (LOX-1) has been cloned from human aortic endothelial cells, and has a sequence identical to that from human lung. Previous studies showed that human LOX-1 can recognize modified LDL, apoptotic cells and bacteria. To further explore the relationship between the structure and function of LOX-1, a mutagenesis study was carried out. Our results showed that the carbohydrate recognition domain (CRD) was the ligand-binding domain of human LOX-1. We also investigated the sequences and residues in CRD that were essential for protein cell surface localization and ligand binding. LOX-1s carrying a mutation on each of six Cys in CRD resulted in a variety of N-glycosylation and failed to be transported to the cell surface. This was strong evidence for the involvement of all six Cys in the intrachain disulfide bonds required for proper folding, processing and transport of LOX-1. The C-terminal sequence (KANLRAQ) was also essential for protein folding and transport, while the four final residues (LRAQ) were involved in maintaining receptor function. Both positive charged (R208, R209, H226, R229 and R231) and non-charged hydrophilic (Q193, S198, S199 and N210) residues were involved in ligand binding, suggesting that ligand recognition of LOX-1 is not merely dependent on the interaction of positively charged residues with negatively charged ligands.

Expression of the Cytoplasmic Domain of NodC as an Active Form in Drosophila S2 Cells

NodC, a membrane protein that catalyzes the synthesis of the chitin oligosaccharide chain, was successfully produced in a soluble form. The truncated NodC gene encoding only the cytoplasmic domain that deletes the hydrophobic N-terminus expressed both cytoplasmic and secreted proteins in Drosophila Schneider 2 cells. The expressed protein maintained the ability to synthesize chitin oligosaccharides, primarily (GlcNAc)4, similar to the native membrane-bound NodC. This evidence suggests that only the large hydrophilic loop of NodC is efficient for enzymatic activity. Moreover, immobilizing the soluble NodC to a solid phase has no effect on the enzymatic activity. This, anchoring NodC is not necessary for its activity.

Cycloamylose as an efficient artificial chaperone for protein refolding

High molecular weight cyclic alpha-1,4-glucan (referred to as cycloamylose) exhibited an artificial chaperone property toward three enzymes in different categories. The inclusion properties of cycloamylose effectively accommodated detergents, which keep the chemically denatured enzymes from aggregation, and promoted proper protein folding. Chemically denatured citrate synthase was refolded and completely recovered it's enzymatic activity after dilution with polyoxyethylenesorbitan buffer followed by cycloamylose treatment. The refolding was completed within 2 h, and the activity of the refolded citrate synthase was quite stable. Cycloamylose also promoted the refolding of denatured carbonic anhydrase B and denatured lysozyme of a reduced form.

Lack of effect of running training at two intensities on cardiac myosin isozyme composition in rats

Little information is available regarding the influence of the intensity of endurance training over biochemical profiles in cardiac muscle. We assessed the effect of running training at two different intensities on cardiac myosin isozyme composition in rats. Male Sprague-Dawley rats (4 weeks old) were divided into four groups: sedentary control (SC), trained at 20 m/min (T20), trained at 40 m/min (T40), and weight-matched sedentary control (WMSC) groups. The T20 and T40 group rats were trained by treadmill running for 60 min/d, 5 d/week at 20 or 40 m/min, respectively, for 11 to 12 weeks. In both groups the left ventricle was significantly heavier than in WMSC animals. The ratio of left ventricle weight to body weight was significantly greater in T40 rats than in either the untrained (SC and WMSC) or trained T20 rats. Thus the extent of exercise-induced cardiac hypertrophy appears to be influenced by the intensity of running training. However, neither of the training programs (1) induced a change in cardiac myosin isozyme composition or (2) had any effect on myocardial succinate dehydrogenase or citrate synthase activity. These results suggest that although the intensity of running training may play an important role in cardiac morphological adaptation, it does not modulate the cardiac biochemical adaptation to running training.

P23H rhodopsin transgenic rat: correlation of retinal function with histopathology

PURPOSE

To correlate retinal functional changes with structural changes in P23H rhodopsin transgenic rats as a model of autosomal dominant retinitis pigmentosa.

METHODS

P23H heterozygote (lines 1 and 3) and Sprague-Dawley control rats were studied at 4 to 29 weeks by retinal histology, electroretinogram (ERG), and a-wave transduction modeling.

RESULTS

Both line 1 (faster degeneration) and line 3 (slower degeneration) showed progressive rod outer segment (ROS) shortening and outer nuclear layer (ONL) cell loss with age. ERG b-wave maximum amplitude (Vb(max)) decreased with age, but b-wave threshold remained constant within each line despite progressive ONL thinning and ROS shortening. The only exception was in line 1 at 29 weeks, which showed a slight threshold change relative to earlier ages. Va(max) and a-wave threshold changed more rapidly and were more sensitive than the b-wave in reflecting histologic degeneration. Va(max) was linearly proportional to the product of (ROS x ONL) across a two log unit range of data combined from both lines. The photopic b-wave was normal for both lines until the ONL thinned beyond 50%. Phototransduction sensitivity was normal for both lines, and dark-adaptation recovery after bleaching rhodopsin was normal.

CONCLUSIONS

The P23H transgenic rat has a slow rod degeneration with initially normal cone function, consistent with clinical findings of P23H patients. However, the normal bleach recovery and the normal phototransduction sensitivity in this rat model are different from human P23H disease. a-Wave measures were more sensitive than the b-wave for tracking changes. b-Wave threshold was inexplicably poor for tracking degeneration. Although line 1 degenerated faster than line 3, the functional-structural correlates were the same. The tight linear relationship between saturated a-wave amplitude and the product of (ROS x ONL) indicates that the density of cGMP-gated channels per unit ROS plasma membrane area remains constant over a wide range of degenerations.

The effect of calcium channel blocker diltiazem on photoreceptor degeneration in the rhodopsin Pro213His rat

PURPOSE

To determine whether the calcium channel blocker D-cis-diltiazem promotes photoreceptor survival in rats with the Pro23His rhodopsin mutation.

METHODS

Heterozygous Pro23His rhodopsin line 1 rats (n = 11) were treated daily, according to a protocol applied successfully in rd mice, with D-cis-diltiazem hydrochloride increased incrementally from 21 to 54 mg/kg in a divided dose (8 AM and 8 PM) administered by intraperitoneal (i.p.) injection for 21 days, beginning on days of age 10 through 12. Saline-treated line 1 rats (n = 6) received i.p. injections of an equal volume of 0.9% saline. Analysis on day 35 of age included dark-adapted corneal electroretinogram (ERG) b- and a-waves recorded from threshold to 0.63 log candela-seconds [cd-s]/m2, saturated a-waves elicited with a 2.1 log cd-s/m2 flash, and morphometry of the outer nuclear layer (ONL) and rod outer segments (ROS).

RESULTS

ONL width and cell counts of diltiazem-treated and saline-treated animals at 35 days were reduced to 64%-68% of 15-day-old untreated P23H line 1 retinas. No photoreceptor rescue was found by measuring ONL width (P = 0.84), cell count (P = 0.42), or ROS length (P = 0.85). Functional assays by ERG b-wave threshold (P = 0.57), b-wave maximum amplitude (P = 0.46), and saturated a-wave amplitude (P = 0.59) also showed no rescue.

CONCLUSIONS

D-cis-Diltiazem did not rescue photoreceptors of Pro23His rhodopsin mutation line 1 rats treated according to the protocol used in rd mouse.