Changes in light-induced fluorescence of cervical collagen in guinea pigs during gestation and after sodium nitroprusside treatment.

Light-induced fluorescence (LIF) of collagen was used to investigate in vivo changes in cervical collagen in guinea pigs during gestation and following sodium nitroprusside treatment. Natural fluorescence of collagen is due to collagen cross-linking molecules that connect single collagen fibers and therefore provide rigidity of the cervical stroma. LIF of cervical collagen was measured from the surface of the exocervix in anesthetized nonpregnant and timed pregnant guinea pigs at different times of gestation with an instrument designed in our lab (Collascope). Measurements were also performed in guinea pigs at midgestation before and 8 hours after intracervical treatment with sodium nitroprusside. Collagen fluorescence decreased significantly as pregnancy progressed, reached lowest values at delivery, and increased gradually postpartum. Treatment with sodium nitroprusside, but not with the vehicle, caused a significant decrease in LIF (p = 0.007). We conclude, that LIF changes in the cervix reflect the gradual cervical softening (ripening) during pregnancy and the return to the rigid state of the cervix postpartum. Cervical softening during pregnancy, and after sodium nitroprusside treatment, is associated with a decrease in collagen cross-links. Measurements of LIF can be used to investigate cervical softening in vivo.     

A metabolomic approach to ionotropic glutamate receptor subtype function: a nuclear magnetic resonance in vitro investigation.

A range of behaviours are elucidated via ionotropic glutamate receptors (iGluR). In this work, we examined the acute activation of iGluRs by a range of receptor ligands and effectors to see whether distinguishable metabolic sequelae were elucidated by the activity. We used a guinea-pig brain cortical tissue slice model using targeted receptor ligands ((RS)-(tetrazol-5-yl)glycine (TZG), (5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801, dizocilpine), cis-4-[phosphomethyl]-piperidine-2-carboxylic acid (CGS 19755), (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, (2S, 3S, 4S)-2-carboxy-4-(1-methylethenyl)-3-pyrrolidineacetic acid (kainate) and D-serine (D-Ser), as well as compounds (quinolinic acid and kynurenic acid (KynA)) involved in some neuroinflammatory responses. The data were derived using 13C and 1H NMR spectroscopy, and analysed by metabolomic approaches and multivariate statistics. The metabolic effects of agonists at the three major classes of iGluR were easily separated from each other using this method. The classical N-methyl-D-aspartate receptor agonist TZG and the antagonist CGS 19755 produced excitatory and inhibitory metabolic responses, respectively, while the blocker MK-801 resulted in a significant decrease in net metabolism and produced the largest decrease in all metabolite pool sizes seen by any glutamatergic ligand we have studied. Quinolinic acid and KynA produced similar acute metabolic responses, which were unlike those to TZG or CGS 19755, but similar to that of D-Ser. D-Ser was highly stimulatory of net flux into the Krebs cycle. These data show that the metabolic response to iGluR perturbation in vitro is a sensitive discriminator of function.     

Emergency arteriography in the assessment of penetrating trauma to the lower limbs

One hundred emergency arteriographies (EA) were performed in 87 patients with lower limb trauma due to high-velocity missiles. Thirteen patients had bilateral injuries. In 79 cases, EA findings were positive and led to emergency surgery. In 76 cases an arterial injury was found and treated, a positive predictive value of 96% (76/79). In the other 3 cases, no arterial lesion was found (3 false positives). Among the 21 patients with normal findings from angiography, 10 had surgical exploration because of high clinical suspicion of vascular injury. Arterial injury was found in 2 cases (2 false negatives). In 8 patients, arteriography modified the surgical procedure. In the 11 remaining patients, clinical and echo Doppler follow-up results were normal, a negative predictive value of 90% (19/21). Sensitivity was 97%, specificity 86%, and accuracy 95%. These data show that arteriography in stable patients is a safe and accurate procedure. It permits avoidance of unnecessary surgical exploration in selected patients and helps modify the surgical procedure.     

Reevaluation of steroid tapering after steroid pulse therapy for heart rejection.

A retrospective analysis was conducted to determine the efficacy and complications resulting from steroid pulse therapy, with or without a steroid taper, in 93 episodes of heart transplant rejection that occurred in 72 patients (58 men, 14 women; mean age, 47.6 years). Each rejection episode was classified according to severity (Texas Heart Institute endomyocardial biopsy scale) and the treatment. Group 1 included 25 episodes of grade 7, 8, 9, or 10 rejection (International Society for Heart Transplantation [ISHT] grade IIIB or IV) that were treated with high-dose methylprednisolone (2.5 to 3.0 gm) and a steroid taper of 1.75 gm over 30 days. Group 2 included 16 episodes of rejection, with the severity of rejection and methylprednisolone pulse therapy being similar to that in group 1, but without a steroid taper. The results of treatment in group 1 were compared with those in group 2. Group 3 included 12 episodes of grade 5, 6, or 7 rejection (ISHT grade IIIA or IIIB) that were treated with moderate-dose methylprednisolone (1.0 to 2.0 gm) and a steroid taper, as described. Group 4 included 40 episodes of rejection, with the severity of rejection and methylprednisolone therapy being similar to that of group 3, but without a steroid taper. The results of treatment in group 3 were compared with those in group 4. No statistically significant differences were found among the groups regarding subsequent episodes of rejection or infection within 3 months of treatment. No statistically significant difference was noted among the groups in the number of rejection episodes requiring additional therapy to control the rejection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of glutathione <Emphasis Type="Italic">S</Emphasis>-transferase Pi isoform (GSTP1) single-nucleotide polymorphisms and macular telangiectasia type 2

Recent imaging studies have suggested that macular pigment is decreased centrally in macular telangiectasia type 2 (MT2). The uptake of xanthophyll pigment into the macula is thought to be facilitated by a xanthophyll-binding protein (XBP). The Pi isoform of glutathione S-transferase (GSTP1) represents one such XBP with high binding affinity. This case–control study aimed to determine whether two common single-nucleotide polymorphisms (SNPs) of GSTP1 were associated with MT2. DNA samples from 39 cases and 21 controls were collected. Two polymorphic sites of Ile105Val and Ala114Val in exons 5 and 6 respectively, of the GSTP1 gene were analysed. Comparison of alleles and genotypes between cases and controls indicated that there were no statistically significant differences for either the Ile105Val SNP (P = 0.43) or the Ala114Val SNP (P = 0.85), or for any combinations; however, the homozygous at-risk genotype (GG) of the Ile105Val SNP was present in 8% of cases but absent in controls. This study found no statistically significant association between two common GSTP1 SNPs and MT2; however, a trend towards a greater frequency of the GG genotype of the Ile105Val SNP in cases is of great interest. The biological plausibility of disturbed macular pigment uptake in MT2 makes GSTP1 an excellent candidate gene. Further investigation is warranted in future studies of MT2.     

Two-wavelength fundus autofluorescence and macular pigment optical density imaging in diabetic macular oedema

Purpose

To evaluate the application of 488 and 514 nm fundus autofluorescence (FAF) and macular pigment optical density (MPOD) imaging in diabetic macular oedema (DMO) and to demonstrate the typical imaging features.

Patients and Methods

A hundred and twenty-five eyes of 71 consecutive patients with diabetic retinopathy who underwent examination at a specialist university clinic employing a modified Heidelberg Retina Angiograph, using two different light sources of 488 and 514 nm wavelength, were retrospectively reviewed. MPOD images were calculated using modified Heidelberg Eye Explorer software. All images were evaluated by two independent masked graders. Features from FAF and MPOD images were correlated with optical coherence tomography (OCT) imaging findings and inter-grader variability, sensitivity and specificity were calculated using OCT as reference.

Results

Sixty-seven eyes had DMO on OCT. The inter-grader variability was 0.84 for 488 nm FAF, 0.63 for 514 nm FAF and 0.79 for MPOD imaging. Sensitivity and specificity for detection of DMO were 80.6 and 89.7% for 488 nm FAF; 55.2 and 94.8% for 514 nm FAF; and 80.6 and 91.4% for MPOD imaging. In 488 nm FAF and MPOD imaging, DMO was better visualised in comparison with 514 nm FAF imaging, P<0.01. MPOD revealed displacement of macular pigment by intraretinal cysts.

Conclusion

MPOD imaging, and particularly its combination with 488 nm and 514 nm FAF, provides a valuable addition to OCT in the evaluation of DMO and is clinically useful in rapid en-face assessment of the central macula.     

Gentherapie bei Netzhautdystrophien

Genetic mutations are the cause of inherited retinal dystrophies. The underlying genetic basis of these diseases suggests that a gene therapy approach is logical either to replace or reduce the expression of defective genes. The first proof-of-concept clinical studies in patients with Leber's congenital amaurosis have suggested that retinal gene therapy is safe and potentially effective, at least for specific disease entities. In contrast to pharmacological treatment gene therapy has the advantage of being able to express a protein within specific cell populations and is a potentially definitive therapy. Besides replacing deficient genes in inherited diseases, additional strategies that might broaden the application of retinal gene therapy are also being developed. These include the permanent expression of neuroprotective substances or photosensitive molecules (so-called optogenetics). This overview discusses the current clinical strategies and potential problems of retinal gene therapy.