Soluble endoglin versus sFlt-1/PlGF ratio: detection of preeclampsia, HELLP syndrome, and FGR in a high-risk cohort

The angiogenic factors sFlt-1 and PlGF play an established role in the detection of preeclampsia (PE). Recent data suggest that sEng might contribute to the pathogenesis of PE. However, only a few studies so far have addressed its role.This monocentric cross-sectional study of high-risk pregnancies aims to compare the levels of sFlt-1/PlGF ratio and sEng depending on different placental-related adverse pregnancy outcomes. The statistical analysis takes into account Pearson's correlation coefficient between angiogenic factors, the area under the curve estimates (AUCs) for detection, and adjusted odds ratios (aOR) with 95% confidence intervals (95%-CIs). The analysis included 206 patients: 60 controls, 90 PE (59 EOPE, 35 LOPE), 94 FGR, and 35 HELLP cases. Some outcomes overlapped because FGR commonly complicated PE and HELLP syndrome. Serum levels of sFlt-1/PlGF and sEng correlated with each other. Higher levels were observed in HELLP syndrome and EOPE cases. AUCs for sFlt-1/PlGF ratio and sEng were, respectively, 0.915 (95%-Cl 0.87-0.96) and 0.872 (95%-Cl 0.81-0.93) in PE, 0.895 (95%-Cl 0.83-0.96) and 0.878 (95%-Cl 0.81-0.95) in HELLP syndrome, 0.891 (95%-Cl 0.84-0.94), and 0.856 (95%-Cl 0.79-0.92) in FGR.aORsfor sFlt-1/PlGF ratio and sEng were, respectively: 2.69 (95%-Cl 1.86-3.9) and 2.33 (95%-Cl 1.59-3.48) in PE, 2.38 (95%-Cl 1.64-3.44) and 2.28 (95%-Cl 1.55-3.4) in FGR, and 2.10 (95%-Cl 1.45-3.05) and 1.88 (95%-Cl 1.31-2.69) in HELLP syndrome. In addition, the aORs between sFlt-1/PlGF and sEng were very similar but higher for PE and FGR than HELLP syndrome.In conclusion,sEng performed similarly to sFlt-1/PlGF to detect placental dysfunctions.

RAS testing of liquid biopsy correlates with the outcome of metastatic colorectal cancer patients treated with first-line FOLFIRI plus cetuximab in the CAPRI-GOIM trial

Background

Liquid biopsy is an alternative to tissue for RAS testing in metastatic colorectal carcinoma (mCRC) patients. Little information is available on the predictive role of liquid biopsy RAS testing in patients treated with first-line anti-EGFR monoclonal antibody-based therapy.

Patients and methods

In the CAPRI-GOIM trial, 340 KRAS exon-2 wild-type mCRC patients received first-line cetuximab plus FOLFIRI. Tumor samples were retrospectively assessed by next generation sequencing (NGS). Baseline plasma samples were analyzed for KRAS and NRAS mutations using beads, emulsion, amplification, and magnetics digital PCR (BEAMing). Discordant cases were solved by droplet digital PCR (ddPCR) or deep-sequencing.

Results

A subgroup of 92 patients with available both NGS data on tumor samples and baseline plasma samples were included in this study. Both NGS analysis of tumor tissue and plasma testing with BEAMing identified RAS mutations in 33/92 patients (35.9%). However, 10 cases were RAS tissue mutant and plasma wild-type, and additional 10 cases were tissue wild-type and plasma mutant, resulting in a concordance rate of 78.3%. Analysis of plasma samples with ddPCR detected RAS mutations in 2/10 tissue mutant, plasma wild-type patients. In contrast, in all tissue wild-type and plasma mutant cases, ddPCR or deep-sequencing analysis of tumor tissue confirmed the presence of RAS mutations at allelic frequencies ranging between 0.15% and 1.15%. The median progression-free survival of RAS mutant and wild-type patients according to tissue (7.9 versus 12.6 months; P = 0.004) and liquid biopsy testing (7.8 versus 13.8 moths; P < 0.001) were comparable. Similar findings were observed for the median overall survival of RAS mutant and wild-type patients based on tissue (22.1 versus 35.8 months; P = 0.016) and plasma (19.9 versus 35.8 months; P = 0.013) analysis.

Conclusion

This study indicates that RAS testing of liquid biopsy results in a similar outcome when compared with tissue testing in mCRC patients receiving first-line anti-EGFR monoclonal antibodies.

High-resolution microarray analysis unravels complex Xq28 aberrations in patients and carriers affected by X-linked blue cone monochromacy

The human X chromosome contains ∼ 1600 genes, about 15% of which have been associated with a specific genetic condition, mainly affecting males. Blue cone monochromacy (BCM) is an X-linked condition caused by a loss-of-function of both the OPN1LW and OPN1MW opsin genes. The cone opsin gene cluster is composed of 2-9 paralogs with 99.8% sequence homology and is susceptible to deletions, duplications, and mutations. Current diagnostic tests employ polymerase chain reaction (PCR)-based technologies; however, alterations remain undetermined in 10% of patients. Furthermore, carrier testing in females is limited or unavailable. High-resolution X chromosome-targeted CGH microarray was applied to test for rearrangements in males with BCM and female carriers from three unrelated families. Pathogenic alterations were revealed in all probands, characterized by sequencing of the breakpoint junctions and quantitative real-time PCR. In two families, we identified a novel founder mutation that consisted of a complex 3-kb deletion that embraced the cis-regulatory locus control region and insertion of an additional aberrant OPN1MW gene. The application of high-resolution X-chromosome microarray in clinical diagnosis brings significant advantages in detection of small aberrations that are beyond the resolution of clinically available aCGH analysis and which can improve molecular diagnosis of the known conditions and unravel previously unrecognized X-linked diseases.

Melainomania: a study on 100 subjects

AIM

The melainomania is a psychological and skin syndrome and it expresses the obsessive need of tanned skin in a complete and constant way. We searched for the psycho-patogenetic factors of the syndrome and the psychological and skin ends point useful to evaluate the psychic and skin damages.

METHODS

Seventy-two women and 28 men, aged 38-56 years, who were used to a constant photo exposure have been examined. We have considered the psychosocial damages by Rorschach e Machover tests and by psychologist-subject interviews, skin damages by Glogau signs and by echography. Furthermore, the subjects have been submitted to a psychotherapeutic treatment.

RESULTS

The tests and the interviews have underlined obsessive lines, dependence, bodily misperception, low index of reality. The Spearman correlations among clinical signs and echographic findings shows high significance. The psychotherapy has reduced the uneasiness in 66 women and 24 men. Each event that produces uneasiness requires a rationalization process that individualizes in successive phases logical justifications for the lived uneasiness and for the perceived consequences. The rational psycho mechanics is a new method that has identified the phase of the thought-deviation and it has planned the corrective therapy.

CONCLUSION

The psychological tests, the interviews, the clinical signs and the ultrasound have allowed us to appraise the psychic and skin damages, while the method of the rational psycho mechanics seems to have brought a satisfactory therapeutic result.

Confirmatory tests in the diagnosis of primary aldosteronism

Primary aldosteronism is the most common form of secondary hypertension and patients with hyperaldosteronism are more prone to premature cardiovascular complications compared to essential hypertensives. The diagnostic flow-chart for the diagnosis of PA is performed in three steps: a) screening; b) confirmation; and c) subtype differentiation. Instead of proceeding directly to subtype classification, the recently published Endocrine Society Guidelines recommend that patients with a positive ARR should undergo a confirmatory test, in order to definitively confirm or exclude the diagnosis of PA. The Guidelines recognize four testing procedures: oral sodium loading, saline infusion, fludrocortisone suppression, and captopril challenge. Herein we discuss the diagnostic protocols for these confirmatory tests and highlight both the advantages and contraindications and we discuss studies in which these confirmatory tests have been compared.

Predicting the pathogenicity of RPE65 mutations

To assist in distinguishing disease-causing mutations from nonpathogenic polymorphisms, we developed an objective algorithm to calculate an "estimate of pathogenic probability" (EPP) based on the prevalence of a specific variation, its segregation within families, and its predicted effects on protein structure. Eleven missense variations in the RPE65 gene were evaluated in patients with Leber congenital amaurosis (LCA) using the EPP algorithm. The accuracy of the EPP algorithm was evaluated using a cell-culture assay of RPE65-isomerase activity The variations were engineered into plasmids containing a human RPE65 cDNA and the retinoid isomerase activity of each variant was determined in cultured cells. The EPP algorithm predicted eight substitution mutations to be disease-causing variants. The isomerase catalytic activities of these RPE65 variants were all less than 6% of wild-type. In contrast, the EPP algorithm predicted the other three substitutions to be non-disease-causing, with isomerase activities of 68%, 127%, and 110% of wild-type, respectively. We observed complete concordance between the predicted pathogenicities of missense variations in the RPE65 gene and retinoid isomerase activities measured in a functional assay. These results suggest that the EPP algorithm may be useful to evaluate the pathogenicity of missense variations in other disease genes where functional assays are not available.

Fetal borderline cerebral ventriculomegaly: clinical significance and management

AIM

The aim of this study was to evaluate the clinical significance and the management of fetal borderline lateral cerebral ventriculomegaly.

METHODS

Fetuses with a sonographic diagnosis of lateral cerebral ventriculomegaly isolated or associated to other fetal malformations were followed monthly and a review of the English-language literature was made.

RESULTS

Of 86 fetuses analyzed, 30 suffered from hydrocephaly (monolateral, bilateral), 56 showed also several other malformations . Chromosomal aberrations is possible also in case of isolated hydrocephaly. Neurological sequelae, mostly a mild to moderate delay in cognitive and/or motor development, is present in 10% of the cases.

CONCLUSIONS

In most cases, isolated borderline lateral cerebral ventriculomegaly has no consequence. However, the risk of cerebral maldevelopment, delayed neurological development and, possibly, chromosomal aberrations is increased. The optimum management of these cases remains uncertain.

Functionally rodless mice: transgenic models for the investigation of cone function in retinal disease and therapy

Two genetically engineered strains of mice were used to characterize murine cone function electroretinographically, without interference of rod-driven responses: (1) mice with a deletion of the gene for the rod transducin alpha-subunit (transducin alpha-/-), and (2) mice with rod arrestin deleted (arrestin -/-). In the first three months of age, both strains have a normal complement of rods and normal rod structure, but transducin alpha-/- mice have no rod-driven responses to light, while rod-driven activity of arrestin -/- mice can be suppressed by a single intense flash for hours. In response to intense flashes the electroretinograms of these strains of mice showed a readily identifiable, pure-cone a-wave of approximately 10 microV saturating amplitude. A 530 nm background that saturates rod responses of wild type mice was found to desensitize the b-wave responses of mice of both transgenic lines, whether the b-waves were driven by photons captured by M- or UV-cone pigments. The desensitizing effect of the 530 nm background on UV-pigment driven responses provides new evidence in support of the hypothesis of functional co-expression of the M-pigment in cones expressing primarily the UV-pigment.

Pigment epithelium-derived factor supports normal Müller cell development and glutamine synthetase expression after removal of the retinal pigment epithelium

In conditions in which the retinal pigment epithelium (RPE) is dystrophic, carries a genetic mutation, or is removed physically, Müller cells undergo degenerative changes that contribute to the retinal pathology. We previously demonstrated that pigment epithelium-derived factor (PEDF), a glycoprotein secreted by the RPE cells with neuroprotective and differentiation properties, protects against photoreceptor degeneration induced by RPE removal. The purpose of the present study was to analyze the putative gliosupportive activity of PEDF on Müller cells of RPE-deprived retinas and assess whether protection of Müller cells was correlated with improved photoreceptor outer segment assembly. Eyes were dissected from Xenopus laevis tadpoles, and the RPE was removed before culturing in medium containing purified PEDF, PEDF plus anti-PEDF, or medium alone. Control eyes matured with an adherent RPE or in medium containing PEDF plus nonimmune serum. Müller cell ultrastructure was examined. Glial fibrillary acidic protein (GFAP) and glutamine synthetase were localized immunocytochemically, and the corresponding protein levels were quantified. In control retinas, Müller cells were structurally intact and formed adherens junctions with neighboring photoreceptors. In addition, they did not express GFAP, whereas glutamine synthetase expression was high. RPE removal dramatically altered the ultrastructure and biosynthetic activity of Müller cells; Müller cells failed to form adherens junctions with photoreceptors and glutamine synthetase expression was suppressed. PEDF prevented the degenerative glial response; Müller cells were ultrastructurally normal and formed junctional complexes with photoreceptors. PEDF also preserved the expression of glutamine synthetase at near-normal levels. The morphogenetic effects of PEDF were blocked by the anti-PEDF antibody. Our study documents the glioprotective effects of PEDF and suggests that maintenance of the proper Müller cell ultrastructure and expression of glutamine synthetase may be necessary to support the proper assembly of photoreceptor outer segments.

Identification of the gene that, when mutated, causes the human obesity syndrome BBS4

Bardet-Biedl syndrome (BBS, MIM 209900) is a heterogeneous autosomal recessive disorder characterized by obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation, and hypogenitalism. The disorder is also associated with diabetes mellitus, hypertension, and congenital heart disease. Six distinct BBS loci map to 11q13 (BBS1), 16q21 (BBS2), 3p13-p12 (BBS3), 15q22.3-q23 (BBS4), 2q31 (BBS5), and 20p12 (BBS6). Although BBS is rare in the general population (<1/100,000), there is considerable interest in identifying the genes causing BBS because components of the phenotype, such as obesity and diabetes, are common. We and others have demonstrated that BBS6 is caused by mutations in the gene MKKS (refs. 12,13), mutation of which also causes McKusick-Kaufman syndrome (hydrometrocolpos, post-axial polydactyly, and congenital heart defects). MKKS has sequence homology to the alpha subunit of a prokaryotic chaperonin in the thermosome Thermoplasma acidophilum. We recently identified a novel gene that causes BBS2. The BBS2 protein has no significant similarity to other chaperonins or known proteins. Here we report the positional cloning and identification of mutations in BBS patients in a novel gene designated BBS4.

Reliability assessment of a rod photoreceptor outer segment grading system

The purpose of this study was to assess the reliability of a rod photoreceptor outer segment (PR-OS) grading system based on the analysis of 1 microm thick retinal sections obtained from Xenopus laevis whole-eye organ cultures. Digitally captured images, representative of the entire spectrum of rod PR-OS organization levels, were selected and coded numerically. A total of 102 individual rod PR-OS profiles were graded according to a six-step classification scheme based on the percentage of rod PR-OS membrane organization. Unweighted (exact agreement) and weighted kappa (kappa) coefficients (for use with ordered categorical rating scales) were calculated. Differences between kappa coefficients were tested for by chi-square analysis. To investigate the intra- and inter-rater variability and the possible presence of an interaction of the measurements with time, a repeated-measures analysis of variance was performed. The overall unweighted and weighted intra-rater kappa coefficients were 0.78 and 0.92, respectively. The overall unweighted and weighted inter-rater kappa coefficients were 0.73 and 0.90, respectively. There was no significant difference between raters or between first and second reading, nor was interaction between raters and time of rating documented. Individual kappa coefficients were equivalent both between raters and between sessions. Intra- and inter-rater agreement was within one step in 100% of cases. The estimated values of the kappa coefficients are consistent with a good to excellent degree of reliability and reproducibility of this rod PR-OS grading system. This system will be useful in the assessment of rod PR-OS morphology in studies of photoreceptor physiology and pathology.

Genotype-phenotype correlations and differential diagnosis in autosomal dominant macular disease

In the past few years, great progress has been made in the understanding of macular diseases. A number of disease-causing genes have been cloned, and numerous loci for other conditions have been mapped. The purpose of this article is to provide an overview of the current understanding of the genotype-phenotype correlations in autosomal dominant macular diseases with an emphasis on differential diagnostic issues. Whenever possible, the molecular correlates have been reviewed and the implications for age-related macular degeneration have been discussed. The many similarities of these diseases to age-related macular degeneration of the atrophic or exudative type, which can be misleading in elderly subjects, have also been addressed. While some conditions yield disease truly confined to the macula, others show widespread retinal involvement on functional testing. Clear-cut genotype-phenotype correlations are possible only for some forms of macular diseases. To further complicate the diagnostic process, there is a considerable degree of clinical overlap between many of them, making the differential diagnostic process potentially challenging. Functional testing, careful assessment of family history and extensive family work-up are essential in differentiating at the clinical level most, but not all, of these disease entities. Awareness of all of these conditions is required to direct correctly diagnostic investigations, to formulate an accurate prognosis, and for proper genetic counseling.

Positional cloning of a novel gene on chromosome 16q causing Bardet-Biedl syndrome (BBS2)

Bardet-Biedl syndrome (BBS) is a genetically heterogeneous autosomal recessive disorder with the primary clinical features of obesity, pigmented retinopathy, polydactyly, hypogenitalism, mental retardation and renal anomalies. Associated features of the disorder include diabetes mellitus, hypertension and congenital heart disease. There are six known BBS loci, mapping to chromosomes 2, 3, 11, 15, 16 and 20. The BBS2 locus was initially mapped to an 18 cM interval on chromosome 16q21 with a large inbred Bedouin kindred. Further analysis of the Bedouin population allowed for the fine mapping of this locus to a 2 cM region distal to marker D16S408. Physical mapping and sequence analysis of this region resulted in the identification of a number of known genes and expressed sequence tag clusters. Mutation screening of a novel gene (BBS2) with a wide pattern of tissue expression revealed homozygous mutations in two inbred pedigrees, including the large Bedouin kindred used to initially identify the BBS2 locus. In addition, mutations were found in three of 18 unrelated BBS probands from small nuclear families.

Lactose supports Muller cell protein expression patterns in the absence of the retinal pigment epithelium

PURPOSE

We have previously shown that lactose, but not mannose, promotes the assembly of nascent photoreceptor outer segments in the absence of the retinal pigment epithelium (RPE). The purpose of the present study was to determine if, in addition to the improved outer segment assembly observed in the presence of lactose, biosynthetic changes in Muller cells could also be detected.

METHODS

The RPE was removed from intact isolated Xenopus embryonic eyes that were allowed to complete differentiation in Niu-Twitty medium, Niu-Twitty with mannose, or Niu-Twitty with lactose. Control retinas matured in vitro with an adherent RPE. Retinal morphology was evaluated for organized folding of outer segment membranes and cell loss. In addition, the expression of three Muller cell proteins, glial fibrillary acidic protein (GFAP), cellular retinaldehyde-binding protein (CRALBP), and glutamine synthetase, was examined.

RESULTS

In control retinas, GFAP is undetectable, CRALBP heavily immunolabels Muller cells, and radial patterns of glutamine synthetase immunoreactivity are present. In the absence of the RPE, Muller cells upregulate GFAP expression, CRALBP labeling is present at a slightly reduced level, and glutamine synthetase immunolabeling is negligible. Neither mannose nor lactose modify significantly the expression of CRALBP. Similarly, both compounds completely prevent the upregulation of GFAP. However, normal glutamine synthetase expression was observed only in the presence of lactose, but not in the presence of mannose. Statistical analyses of slot blot-based protein quantification confirmed our immunochemical results.

CONCLUSIONS

In RPE-deprived retinas supplemented with lactose, Muller cells were morphologically normal. The proper photoreceptor outer segment morphogenesis observed under these conditions was uniquely associated with normal levels of glutamine synthetase expression. The exact significance of this finding with respect to photoreceptor outer segment morphogenesis is unknown. We suggest that glutamine synthetase may be a marker of Muller cell metabolic or structural integrity that may reflect the enhanced ability of these cells, in the presence of lactose, to support photoreceptor outer segment morphogenesis.

Targeted disruption of Müller cell metabolism induces photoreceptor dysmorphogenesis

Within the retina, the Müller cells and photoreceptors are in close physical proximity and are metabolically coupled. It is unknown, however, whether Müller cells affect photoreceptor differentiation and outer segment membrane assembly. The objective of this study was to determine whether targeted disruption of Müller cell metabolism would induce photoreceptor dysmorphogenesis. Intact isolated Xenopus laevis embryonic eyes were cultured in medium with or without Müller cell-specific inhibitors (i.e., alpha-aminoadipic acid and fluorocitrate). To assess Müller cell injury, the gross retinal morphology was examined along with immunocytochemical assessment of Müller cell-specific protein expression patterns. The steady-state levels of opsin were quantified to determine whether the Müller cell inhibitors negatively affected photoreceptor protein synthesis. Müller and photoreceptor cell ultrastructure was scrutinized and the organization of the outer segment membranes was graded. In control retinas, there was no swelling of Müller cell cytoplasm. Glial fibrillary acidic protein (GFAP) was undetectable, whereas glutamine synthetase was abundant. The steady-state level of opsin was high and photoreceptors elaborated properly folded outer segments. Exposure to both Müller cell-specific inhibitors induced swelling of Müller cell endfeet, cytoplasmic paling and alterations of Müller cell-specific protein expression patterns. The steady-state level of opsin in retinas exposed to alpha-aminoadipic acid was unchanged compared with control eyes, whereas, in eyes exposed to fluorocitrate, opsin levels were slightly reduced. The most significant finding was that targeted disruption of Müller cell metabolism adversely affected photoreceptor outer segment membrane assembly, causing dysmorphogenesis of nascent outer segments. These results suggest that the termination signal(s) necessary for proper outer segment folding were disrupted by targeted inhibition of Müller cells and support the hypothesis that Müller cells interact with photoreceptors through mechanisms that may regulate, at least in part, the assembly of photoreceptor outer segment membranes.

Pigment epithelium-derived factor supports normal development of photoreceptor neurons and opsin expression after retinal pigment epithelium removal

Dysfunction of the retinal pigment epithelium (RPE), its loss, or separation from the underlying neural retina results in severe photoreceptor degeneration. Pigment epithelium-derived factor (PEDF) is a glycoprotein with reported neuroprotective and differentiation properties that is secreted in abundance by RPE cells. The "pooling" of PEDF within the interphotoreceptor matrix places this molecule in a prime physical location to affect the underlying neural retina. The purpose of this study was to analyze the morphogenetic activity of PEDF in a model of photoreceptor dysmorphogenesis induced by removal of the RPE. Eyes were dissected from embryonic Xenopus laevis, and the RPE was removed before culturing in medium containing PEDF, PEDF plus anti-PEDF antibodies, or medium alone. Control retinas were maintained with an adherent RPE. Light and electron microscopic analysis was used to examine retinal ultrastructure. Opsin was localized immunocytochemically and quantified as an index of outer segment membranous material and photoreceptor protein expression. Removal of the RPE resulted in an aberrant assembly of photoreceptor outer segments, loss of fine subcellular ultrastructure in photoreceptors, and a reduction in opsin protein levels when compared with control retinas. The addition of PEDF prevented the dysmorphic photoreceptor changes induced by RPE removal. In particular, photoreceptor ultrastructure, outer segment membrane assembly, and steady-state levels of opsin were equivalent to control conditions. Anti-PEDF antibodies completely blocked the morphogenetic activity of PEDF. These results indicate that PEDF is able to mimic the supportive role of the RPE on photoreceptors during the final stages of retinal morphogenesis.

Disease expression of RP1 mutations causing autosomal dominant retinitis pigmentosa

PURPOSE

To determine the disease expression in heterozygotes for mutations in the RP1 gene, a newly identified cause of autosomal dominant retinitis pigmentosa (adRP).

METHODS

Screening strategies were used to detect disease-causing mutations in the RP1 gene, and detailed studies of phenotype were performed in a subset of the detected RP1 heterozygotes using electroretinography (ERG), psychophysics, and optical coherence tomography (OCT).

RESULTS

Seventeen adRP families had heterozygous RP1 changes. Thirteen families had the Arg677ter mutation, whereas four others had one of the following: Pro658 (1-bp del), Ser747 (1-bp del), Leu762-763 (5-bp del), and Tyr1053 (1-bp del). In Arg677ter RP1 heterozygotes, there was regional retinal variation in disease, with the far peripheral inferonasal retina being most vulnerable; central and superior temporal retinal regions were better preserved. The earliest manifestation of disease was rod dysfunction, detectable as reduced rod ERG photoresponse maximum amplitude, even in heterozygotes with otherwise normal clinical, functional, and OCT cross-sectional retinal imaging results. At disease stages when cone abnormalities were present, there was greater rod than cone dysfunction. Patients with the RP1 frameshift mutations showed similarities in phenotype to those with the Arg677ter mutation.

CONCLUSIONS

Earliest disease expression of RP1 gene mutations causing adRP involves primarily rod photoreceptors, and there is a gradient of vulnerability of retinopathy with more pronounced effects in the inferonasal peripheral retina. At other disease stages, cone function is also affected, and severe retina-wide degeneration can occur. The nonpenetrance or minimal disease expression in some Arg677ter mutation-positive heterozygotes suggests important roles for modifier genes or environmental factors in RP1-related disease.

Effect of isosorbide mononitrate on the human optic nerve and choroidal circulations

AIMS

To assess the effects of the nitric oxide donor 5-isosorbide mononitrate (ISMO) on blood flow in the optic nerve head (ON flow) and choroid (Ch flow).

METHODS

Laser Doppler flowmetry was used to measure ON flow and Ch flow in 12 normal subjects by aiming the laser beam at the fovea and at the temporal rim, respectively. In a double masked, randomised, crossover design, each subject received orally on separate days either 20 mg of 5-isosorbide mononitrate (ISMO) or placebo. Ch flow and ON flow were determined monocularly at baseline and 1 hour after dosing. In the last six subjects, additional measurements were obtained at 3 hours. Mean arterial blood pressure (BPm), heart rate, and intraocular pressure (IOP) were monitored, and ocular perfusion pressure (PP) was estimated.

RESULTS

No significant changes in ON flow, PP, IOP, or BPm were observed following placebo. Following ISMO, ON flow increased from baseline by 19.8% (SEM 9.3%) at 1 hour (paired t test, p = 0.058) and by 33.1% (7.5%) at 3 hours (p = 0.007). Compared with the changes following placebo, statistically significant increases in ON flow were observed both at 1 (p = 0.050) and 3 hours (p = 0.041) after ISMO treatment. Compared with placebo, PP decreased significantly 1 hour after ISMO dosing (p = 0.039), mainly as a function of reduced BPm. A significant inverse correlation (R = -0.618; p = 0.032) was observed between the percentage changes in PP and ON flow 1 hour following ISMO administration, but not after placebo. No significant change in foveal Ch flow was documented.

CONCLUSIONS

These results suggest that, in normal subjects, ISMO increases significantly ON flow but not Ch flow. The inverse correlation observed between PP and ON flow suggests that the same mechanism(s) responsible for systemic vasodilatation and blood pressure decrease may also cause the ON flow increase.

Plasma endothelin-1 concentrations in patients with retinal vein occlusions

AIMS

To investigate whether plasma levels of endothelin-1 (ET-1), a potent vasoconstricting peptide that is crucial in regulating retinal blood flow, were elevated in patients with retinal vein occlusion (RVO).

METHODS

ET-1 plasma concentrations were determined by radioimmunoassays in a double blind fashion in a group of 18 selected patients with RVO, in 20 healthy age matched non-smoking, normoglycaemic, normotensive control subjects, and in 15 patients with uncomplicated essential hypertension in the same age range.

RESULTS

Patients with RVO had significantly increased ET-1 plasma levels (14.22 (SD 4.6) pg/ml) compared with both normal subjects (7.90 (1.6) pg/ml; p < 0.05) and hypertensive patients (8.50 (2.9) pg/ml; p < 0.05). The highest concentrations of circulating ET-1 were found in patients with RVO of the ischaemic type (16.97 (3.5) pg/ml; p < 0.01; n = 7). Systemic hypertension alone did not account for the observed increase in plasma ET-1 concentrations.

CONCLUSIONS

These findings raise the possibility that the increased circulating ET-1 levels in patients with RVO may be a marker of the occlusive event, thereby suggesting that ET-1 homeostasis may be relevant to RVO pathogenesis and retinal ischaemic manifestations.

Circulating endothelin-1 in non-insulin-dependent diabetic patients with retinopathy

Endothelin-1 (ET-1), a novel 21-amino acid vasoconstrictive peptide secreted by endothelial cells, has been thought to play a role in various forms of vascular disease. Diabetes mellitus is well known for its association with microvascular damage. To investigate whether ET-1 levels may be related to microangiopathy in diabetes mellitus, plasma ET-1 levels were measured in two groups of diabetic patients: A) 47 patients with non-insulin dependent diabetes mellitus (NIDDM) and retinopathy (28 M, 19 F; mean age 60.7+/-8.5 yrs) but without nephropathy (microalbuminuria < 30 mg/day) and hypertension (SBP < 140, DBP < 90 mmHg); group A was divided in three subgroups based on the severity of retinopathy: a) 16 with background retinopathy; b) 21 with pre-proliferative retinopathy; c) 10 with proliferative retinopathy. B) 8 patients with insulin-dependent diabetes mellitus (IDDM) recently diagnosed (6 M, 2 F; 16.4+/-3.8 yrs) without complications. C) 28 healthy subjects (HS) (16 M, 12 F; 47.8+/-11.8 yrs) as controls. In the NIDDM group the ET-1 concentration was significantly higher (17.3+/-2.4 pg/ml) than both in the HS (8+/-4.7 pg/ml) and IDDM patients (10.2+/-3.7 pg/ml) (p < 0.0001). In the subgroups with retinopathy the ET-1 levels were a) 15.1+/-4.3 pg/ml; b) 22.2+/-6.8 pg/ml and c) 16.6+/-5.1 pg/ml. These values were significantly elevated as compared to HS (p<0.001; p < 0.0001; p < 0.002, respectively), being the highest levels of ET-1 observed in the NIDDM patients with pre-proliferative retinopathy. In conclusion our study revealed that the ET-1 concentrations are elevated in NIDDM patients with retinopathy especially in those patients with pre-proliferative retinopathy.

The ocular phenotype of the Bardet-Biedl syndrome. Comparison to non-syndromic retinitis pigmentosa

PURPOSE

To investigate 20 patients affected with Bardet-Biedl (BB) syndrome and compare them to an age-matched group of 70 non-syndromic patients with retinitis pigmentosa (RP) to identify hallmarks peculiar to the BB phenotype.

METHODS

Patients were examined clinically and with functional tests (color vision, kinetic perimetry, electroretinography, ocular motility tests). Fundus findings were numerically graded for statistical purposes.

RESULTS

Recurrent ocular features in BB patients were early and severe reduction of visual acuity, constantly altered color vision, high incidence of strabismus and nystagmus, mild-to-severe atrophic changes of the optic disc, and frequently absent or minimal pigmentary retinal changes. Visual acuity was more closely correlated to optic disc than to macular conditions. These findings were remarkably different from non-syndromic RP.

CONCLUSIONS

This investigation further suggests that retinopathy in BB syndrome has features distinctive from those in non-syndromic RP. The early occurrence of optic disc atrophy in the BB syndrome, even in those patients with healthy maculas, suggests that optic atrophy could often be primary in nature and might play a major role in decreasing central vision in BB patients. Variability of some findings is in line with the documented heterogeneity of the BB syndrome.

Autosomal-dominant retinitis pigmentosa associated with an Arg-135-Trp point mutation of the rhodopsin gene. Clinical features and longitudinal observations

PURPOSE

To report the clinical and functional characteristics of patients affected with autosomal-dominant transmitted retinitis pigmentosa (adRP) from a large Italian pedigree in which a point mutation predicting the Arg-135-Trp change of rhodopsin was identified by polymerase chain reaction-single-strand conformation polymorphism analysis.

METHODS

Seven patients, ranging in age from 6 to 41 years, underwent a full clinical ophthalmologic evaluation, kinetic visual field testing, and electroretinographic testing.

RESULTS

In agreement with previous reports, this rhodopsin mutation yielded a particularly severe phenotype, both clinically and functionally. The evaluation of patients from this pedigree in the first and second decade of life demonstrated that retinal function is still electroretinographically measurable at least until 18 years of age, although reduced to 2% to 4% of normal. Longitudinal measures showed that the rate of progression of the disease was unusually high, with an average 50% loss per year of electroretinographic amplitude and visual field area with respect to baseline. Later in the course of the disease, macular function is also severely compromised, leaving only residual central vision by the fourth decade of life.

CONCLUSIONS

The phenotype associated with mutations in codon 135 of the rhodopsin molecule appears to have an unusually high progression rate and yields an extremely poor prognosis. These distinctive features make the Arg-135-Trp phenotype substantially different from the general RP population, and also from many of the other adRP pedigrees with known rhodopsin mutations reported to date.

Electroretinographic alterations in the Laurence-Moon-Bardet-Biedl phenotype

Maximal 0.5-Hz and cone 30-Hz ERG responses were recorded from 19 patients showing a Laurence-Moon-Bardet-Biedl (LMDD) phenotype. Off-line averaging of 80 to 100 iterations was routinely performed. When needed, our previously described low-noise techniques and off-line fast Fourier transform procedures were used. The maximal ERG response was non-detectable in 52.6% of cases. About half of the recordable signals were below 5% of the lower normal amplitudes. Cone 30-Hz ERGs were measurable in 64.7% of cases. Of these, 63% of tracings were below 5% of the lower normal range. In most cases no dystrophic pattern was definable, due to severe reduction of both signals. Statistical analyses showed no correlation between ERG amplitudes and residual visual field areas. Clinical and electroretinographic observations suggest that retinopathy in most LMBB patients is a widespread form of degeneration, initially affecting rods but rapidly involving cones as well. However, there are also cases with a clear-cut cone-rod pattern, with fairly well preserved maximal ERG responses. The lack of correlation between maximal ERG responses and visual field residual areas, different from non-syndromic retinitis pigmentosa (RP) patients, could be related either to a low reliability of visual field testing in LMBB patients or to mechanisms accounting for the ongoing retinal degeneration in LMBB syndrome that are different from those of pure RP. Variable findings are in line with the documented genetic heterogeneity of the syndrome.

Correlation between Goldmann perimetry and maximal electroretinogram response in retinitis pigmentosa

To evaluate the relationship between Goldmann perimetry and maximal electroretinographic responses in patients with retinitis pigmentosa, analyses were performed on 220 affected subjects and separately on two subgroups with autosomal dominant (n = 35) and autosomal recessive (n = 29) inheritance. Electroretinograms were recorded averaging 100 iterations elicited with a 20-lux/s, 0.5-Hz white flash ganzfeld stimulation. The peripheral isopters of the visual fields were delimited with I4e, IIIe and V4e targets, measured on conventional perimetry charts with a light pen and expressed in square centimeters. Unlike most previously published reports, this investigation showed a definite correlation (p = 0.0001) between maximal electroretinographic response amplitude and visual field areas. This correlation was more evident for I4e and IIIe isopters (r = 0.89 and 0.87, respectively) than for V4e isopter (r = 0.69). This phenomenon appears to be related to distortion occurring on standard isometric charts and to spatial summation effects in the peripheral field. Such correlations held for both the autosomal dominant and autosomal recessive subgroups. It appears that, if enough accuracy is provided, maximal electroretinographic responses and Goldmann visual fields are both good measures of the remaining functioning retina in nonsyndromic retinitis pigmentosa, irrespective of inheritance models and dystrophic patterns.

Clinical heterogeneity of dominant optic atrophy: the contribution of visual function investigations to diagnosis

BACKGROUND

The variability of the visual function impairment in dominant optic atrophy (DOA) makes it difficult to diagnose the disease within genealogies. Physiologic investigations were conducted on a family with DOA to evaluate methods of detecting clinical and subclinical signs in obligate heterozygotes, in order to identify affected subjects within the genealogy and to formulate the individual and reproductive risks.

METHODS

Investigations included tests for color vision, contrast sensitivity function (CSF), kinetic and static computerized perimetry, transient pattern reversal visual evoked potentials (VEPs) and steady-state flash VEPs.

RESULTS

Eight subjects from the pedigree were diagnosed as having DOA. Two of them were unaware of their affection, and six showed wide clinical variability. CSF paralleled the central visual impairment, but was also slightly impaired in the two unaware subjects. Static computerized perimetry disclosed mild sensitivity defects in the central visual fields in these two patients. VEPs showed heterogeneous results as well, ranging from normal findings to severely altered tracings.

CONCLUSIONS

This investigation suggests that combined clinical and functional evaluation is necessary to diagnose DOA. Particularly, the combined use of computerized perimetry, CSF, and VEPs allowed the identification of cases at a subclinical stage.

Autosomal dominant simple microphthalmos

Congenital bilateral microphthalmos is a rare malformation of the eye, which ranges from extreme to mild reduction of total axial length. Microphthalmos may occur as an isolated ocular abnormality or as part of a systemic disorder, and different classifications of the condition have been attempted. We describe a large pedigree with 14 persons in four generations affected with bilateral microphthalmos without other ocular or systemic signs. An autosomal dominant trait with complete penetrance is proposed. Five subjects underwent a complete ophthalmological evaluation. The total axial length was measured by A scan ultrasonography in all persons. Ultrasonography showed a reduction of the total axial length (range 18.4-19.7 mm) and a reduced vitreous cavity length (range 11.4-13.5 mm) in all investigated patients. All the patients had microcornea (range 8-9.7 mm). No other ocular anomalies or associated systemic malformations were found. A review of published reports also suggests that simple, partial, posterior, pure microphthalmos and nanophthalmos are similar clinical entities sharing total axial length and vitreous cavity length reduction. Therefore, the term simple microphthalmos is proposed to identify these clinical conditions.

Low-noise electroretinogram recording techniques in retinitis pigmentosa

The achievement of a sharp retinal signal depends on many factors, particularly the stability of the electrodes on the corneal surface, the maximal reduction of electrical and electromagnetic disturbances and the avoidance of the noise caused by events that are synchronous with the stimulation. The availability of a low-noise recording system becomes critical in the detection of the electroretinogram in patients with retinitis pigmentosa. We studied an electroretinographic recording technique specifically designed to enhance the signal-to-noise ratio in patients with retinitis pigmentosa. The main features of the method are a membrane suction pump connected to the corneal electrodes to improve contact lens stability on the corneal surface, and a differential derivation system to record the signal. One corneal electrode is used as the recording electrode, while the other, acting as the reference electrode, is covered during full-field ganzfeld stimulation. In addition, computerized averaging and signal postrecording analyses were performed on 100 iterations. The methods described here resulted in a sharp reduction in the number of undetectable electroretinograms in our case material (28.8%). This investigation demonstrates that some of the undetectable signals reported in the literature may be due to noisy recording methods rather than to actually extinguished retinal responses.

Electrophysiologic monitoring of diabetic retinopathy in pregnancy

The authors studied the correlations between electroretinographic, ophthalmologic, and clinical parameters in 30 pregnant women (20 with diabetes and 10 control subjects). Diabetic patients were divided into two groups: group 1 included 11 cases of insulin-dependent diabetes (IDDM); and group 2 included 6 cases of noninsulin-dependent diabetes (NIDDM) and 3 cases of gestational diabetes (GDM). Adapto-electroretinography (AERG) was used as the main monitoring parameter, and in particular, the relationship between the cone-mediated (b1) and rod-mediated (b2) components of the b wave (b2/b1 ratio) 7 minutes after photobleaching was studied. The results indicate that the b2/b1 ratio can detect functional modifications before the onset of ophthalmoscopically detectable retinopathy. Significant statistical correlations were demonstrated both between the type of diabetes and AERG responses, and between metabolic control (HbA1c values) and AERG alterations. A higher maternofetal complication rate in those patients with severe and frequent AERG alterations during pregnancy also was found.

Emergency treatment of the complications of giant liver hemangiomas

The authors discuss the problems of emergency treatment of cavernous hemangiomas of the liver. Five cases were observed and treated with different techniques, ligation of the hepatic artery, excision of the mass, embolization of the hepatic artery. The results of these procedures were strongly influenced by the patient's previous state. Treatment was successful in three patients, while the procedure adopted was able to stop the hemorrage in the other two patients. The physical state was very important for the prognosis; the two patients arriving at our Institute in deep shock both died.

Effects of chronic exposure to arsenate on the cardiovascular function of rats

Cardiovascular function was studied in anaesthetised male rats which received 50 micrograms/ml of arsenic (as sodium arsenate) in deionised drinking water for 320 days. High urinary excretion of arsenic was found at the end of treatment and the metal accumulated considerably in the kidneys and liver, which both presented slight alterations. No histopathological modifications were evident in other organs. Base line blood pressure, cardiac inotropism, and chronotropism and cardiovascular reactivity to noradrenaline, acetylcholine, angiotensin II, bradykinin, histamine, and serotonin did not differ in exposed or in control animals. In the exposed group, however, there was potentiation of the effects of vascular beta-adrenoceptor stimulation and a reduction in the vascular responsiveness to angiotensin I. Chronic arsenic exposure did not affect the baroreflex sensitivity but was able to induce sympathetic hyperactivity or hypersensitivity, or both, possibly associated with an antivagal action. Our results might help to explain the cardiovascular alterations seen in people chronically exposed to high concentrations of arsenic.

Interferences in the spectrophotometric S-diphenylcarbazide determination of environmental hexavalent chromium in a chromium and zinc plating plant

A study on the determination of environmental hexavalent chromium [Cr(VI)] was carried out in a chromium and zinc plating plant. The atmospheric particulate was collected both on glass wool filters and with an electrostatic sampler; Cr(VI) was determined by the S-diphenylcarbazide method. The filtered and electrostatically collected Cr(VI) was extracted with both 1.4% sulfuric acid and 7% sodium carbonate. Strong interference was observed when extraction was carried out with the acid medium. Alkaline extraction permits 95 +/- 6 (+/- SD)% recovery of the total chromium and has been shown to be suitable in releasing Cr(VI). The analyses of the alkaline samples were carried out with the standard addition method to compensate for a depressive interference of 26 +/- 8 (+/- SD)%. The absorbance decrease of the Cr-S-diphenylcarbazide complex is a time function, and it should be measured within a few minutes of the reagent addition.