Aniridia and the ocular surface: Medical and surgical problems and solutions

Congenital aniridia is a multisystemic genetic disease due to a mutation in PAX6 gene which severely affects the development and functionality of the human eyes. In patients affected by the mutation, aside from the absence or defects of iris tissue formation, abnormalities in position or opacities of the crystalline lens, macular hypoplasia, ocular surface disease is the main cause of visual loss and the deterioration of the quality of life of most patients. Limbal stem cell deficiency combined with tear film instability and secondary dry eye cause aniridic keratopathy which, in advanced stages, ends up in corneal opacification. In this paper, the actual knowledge about congenital aniridia keratopathy physiopathology and medical and surgical treatment options and their efficacy are discussed. Indications and results of topical treatments with artificial tears and blood-derivatives in its initial stages, and different surgical techniques as limbal stem cell transplantation, keratoplasty and keratoprostheses are reviewed. Finally, recent advances and results in regenerative medicine techniques with ex vivo stem cell cultivation or other types of cultivated cells are presented.

Influence of surface morphology and internal structure on the mechanical properties and tribological response of Boa Red Tail and Python Regius snake skin

The understanding of the tribological behavior of natural structures has been used as inspiration to design and optimize surfaces for diverse applications in engineering. In the present work, morphological, microstructural, mechanical and tribological characterization of the shed skin of two snake species, namely Boa Red Tail and Python Regius was carried out. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) analyses showed the existence of deterministic patterns, i.e., ordered arrays of geometrical features at the surface, while Transmission Electron Microscopy (TEM) allowed studying the internal structure and chemical composition of the skin sheds. Nanoindentation measurements showed significant variations in hardness and elastic modulus from the surface to the inner layers of the skin, and pin-on-disc tests revealed anisotropic behavior of the friction coefficient (COF) as a function of the sliding direction against balsa wood in dry conditions. Correlations between the friction data, nano-indentation mechanical properties and subsurface skin structure were established for both species taking into account the ways in which the skins' deterministic patterns influence the tribological performance.

Keratolimbal autograft transplantation as a possible new treatment of Lisch epithelial corneal dystrophy

CASE REPORT

The case concerns 64-year-old woman with visual acuity of 20/40 in the right eye. Slit-lamp examination revealed a grey, feathery corneal opacification with intraepithelial microcysts compatible with Lisch epithelial corneal dystrophy (LECD). It was treated with epithelial debridements, contact lenses and mitomycin C, but the opacification recurred within months. The removal of limbus sector and autologous limbal transplantation (KLAT) were used successfully without recurrence.

CONCLUSIONS

After removal of damaged limbus, KLAT should be considered as a treatment option for asymmetric LECD when other treatments have failed.

Assessment of human lymphocyte proliferation associated with metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS), a cluster of various metabolic conditions, has become epidemic and causes increased morbidity and mortality.

PURPOSE

The aim of this study was to compare lymphocyte proliferation under two different stimuli, Concanavalin A (ConA) and insulin, in a group of patients with MetS (Group 1) and a healthy group (Group 2).

METHODS

Group 1 consisted of 53 patients who met the diagnostic criteria for MetS. Group 2 consisted of 63 patients without MetS. All individuals were evaluated for lipid profile and glycemia. Lymphocyte extraction and culture were performed for each subject and lymphocyte proliferation was assessed using the Alamar blue technique.

RESULTS

There was no gender difference between both groups, but in terms of age, there was a significant difference. The use of Con A at concentrations of 1 and 5 µg/mL induced a high lymphocyte proliferation in both groups. In contrast, when different concentrations of insulin were added, no significant changes in lymphocyte proliferation were observed. However, the proliferation of lymphocytes was significantly higher in Group 1 compared to Group 2 under insulin stimulus, which did not happen under ConA stimulation. Even after age and gender correction, this difference was maintained.

CONCLUSIONS

The increased lymphocyte proliferative response to insulin in patients with MetS found in this study suggests a role of the lymphocyte response to insulin in the pathophysiology of MetS. This response may be used as an immuno-biological marker for MetS, although further studies to evaluate its clinical usefulness need to be conducted.

Keratitis caused by Absidia corymbifera in an immunocompetent male with no corneal injuries

Case Report A healthy 55-years-old male went to emergency due to a white infiltrate in the left eye without corneal trauma which partially responds to antibiotic treatment. The infiltrate worsened by the use of topical steroids. Direct microscopic evaluation and Gram stain are a valuable diagnostic tool for the detection of Absidia filaments. There is a successful treatment with anphotericin and posaconazole. Discussion Keratitis caused by Zygomicetes are unusual. This is a rare condition in healthy patients with no corneal trauma. The treatment with amphotericin and posaconazole are synergistic against filamentous fungi.

[Relationship between donor-receptor interface and visual acuity in DSAEK]

OBJECTIVE

To evaluate the relationship between best corrected visual acuity and donor-recipient interface resulting after Descemet's Stripping with Automated Endothelial Keratoplasty (DSAEK).

METHODS

Retrospective review of 46 clinical histories after DSAEK intervention in which 22 patients who fulfilled the inclusion criteria (two with bilateral DSAEK), were studied. All were operated on by the same ophthalmologist from January 2010 until April 2011. Surgical indications were: 19 (72.2%) bullous keratopathy, 3 (12.5%) Fuchs endothelial dystrophy, and 2 (8.3%) previous failed keratoplasty. The visual acuity (VA) was recorded preoperatively, and at three and six months after the operation; the latter two being compared with the interface between donor and recipient after DSAEK measured in a Scheimpflug corneal topography camera (Pentacam(®) model).

RESULTS

After DSAEK surgery 19 eyes had improved visual acuity at three months, and 20 eyes at six months (P<.001). This improvement was compared with the decrease in optical density of the resulting donor-receptor interface, with apositive and significant relationship being found between them (Rho interface 3 months, and improved AV 6 months 0.44, P<.001). However, the interface is negatively and significantly related with visual acuity (Rho 3 m: -0.41, P=.045). Also, patients who had a denser stroma had a worse postoperative visual acuity in relative terms when compared with those who had a less damaged stroma.

CONCLUSIONS

Patients undergoing DSAEK with worse preoperative visual acuity had a greater improvement visual in absolute values and however, they may have achieved a lower relative visual acuity than could be related to a higher refractive interface, as a result of a more damaged preoperative corneal stroma.

Design configurations affecting flow pattern and solids accumulation in horizontal free water and subsurface flow constructed wetlands

The aim of this study was to evaluate the effect of different horizontal constructed wetland (CW) design parameters on solids distribution, loss of hydraulic conductivity over time and hydraulic behaviour, in order to assess clogging processes in wetlands. For this purpose, an experimental plant with eight CWs was built at mesocosm scale. Each CW presented a different design characteristic, and the most common CW configurations were all represented: free water surface flow (FWS) with different effluent pipe locations, FWS with floating macrophytes and subsurface flow (SSF), and the presence of plants and specific species (Typha angustifolia and Phragmites australis) was also considered. The loss of the hydraulic conductivity of gravel was greatly influenced by the presence of plants and organic load (representing a loss of 20% and c.a. 10% in planted wetlands and an overloaded system, respectively). Cattail seems to have a greater effect on the development of clogging since its below-ground biomass weighed twice as much as that of common reed. Hydraulic behaviour was greatly influenced by the presence of a gravel matrix and the outlet pipe position. In strict SSF CW, the water was forced to cross the gravel and tended to flow diagonally from the top inlet to the bottom outlet (where the inlet and outlet pipes were located). However, when FWS was considered, water preferentially flowed above the gravel, thus losing half the effective volume of the system. Only the presence of plants seemed to help the water flow partially within the gravel matrix.

[Technique for removing donor sclera by eyeball extrusion]

PURPOSE

To describe a surgery technique for removing donor sclera tissue after corneo-scleral button excision.

RESULTS

The extrusion technique is easy to perform. It allows the complete scleral extraction its total clean up to be performed, as well as making easier to isolate the retina and uveal tissue. This technique could have an important role in the anatomical and morphological study of ocular structures.

[Calcium transport mechanisms in neuroprotection and neurotoxicity]

INTRODUCTION

Calcium (Ca²(+)) has been found to be involved in neuroprotective processes, by triggering enzymatic cascades that are essential for the synthesis and functioning of the elements that carry out this process. However, it is paradoxical that this ion is one of the main initiators of apoptotic cascades. This difference in its effects is conditioned by differences in the cytoplasmic concentrations.

DEVELOPMENT

Ca²(+) plays a role in the activation of antiapoptotic signals in the neuron when its levels rise moderately, but it also starts apoptotic processes that are triggered mainly by its accumulation in mitochondria. This Ca²(+) comes from the outside or from intracellular deposits by means of different types of transporters. In order to assess the role of Ca²(+) in these processes, it is necessary to consider all the means of transport in an integral manner, since manipulating it pharmacologically gives rise to either protective or toxic processes, due to alterations in the intracellular concentrations of the ion.

CONCLUSIONS

Notable progress has been made in the understanding of the effects of Ca²(+) on the central nervous system and on the mechanisms for controlling and transporting it. It is important to stress that understanding these physiological processes has led to the development of drugs with protective effects and, although most of them are still in the study phase or display important side effects, it remains a promising field that will help in the development of useful therapeutic strategies in neuroprotection.

Celiac disease associated antibodies in persons with latent autoimmune diabetes of adult and type 2 diabetes

BACKGROUND

Celiac Disease (CD) is present in 1-16.4% of patients with type 1 diabetes mellitus. The most important serological markers of CD are anti-endomysial (EMA), anti-tissue transglutaminase (tTGA) and antigliadin antibodies (AGA).

AIM/HYPOTHESIS

The objective of this work is to determine the frequency of tTGA and/or AGA in latent autoimmune diabetes of adult (LADA) and subjects with type 2 diabetes (T2DM), as well as to evaluate their relation with several clinical and biochemical characteristics.

SUBJECTS AND METHODS

Forty three subjects with LADA and 99 with T2DM were studied. The presence of AGA, tTGA was determined in the sera of these patients. The variables: sex, age, duration of diabetes, treatment, body mass index (BMI) and fasting blood glucose concentration were also recorded.

RESULTS

No differences were found in the frequency of celiac disease associated antibodies between LADA and T2DM subjects. The presence of celiac disease related antibodies was more frequent in patients with a normal or low BMI.

CONCLUSIONS

Celiac disease does not seem to be related with pancreatic autoimmunity in type 2 diabetes. Celiac disease causes a decrease of body mass index in type 2 diabetes while pancreatic islet autoimmunity in this entity masks this effect.

[Monolayered amniotic membrane transplantation as a palliative treatment for bullous keratopathy]

PURPOSE

To determine the efficacy of monolayered amniotic membrane transplantation for short and medium-term symptomatic improvement in those cases of bullous keratopathy where a penetrating keratoplasty is not indicated.

METHODS

Amniotic membrane transplantation was performed in five patients with symptomatic bullous keratopathy in which penetrating keratoplasty was not indicated. Data about bandage contact lens need before and after surgery, existence of ocular pain, occurrence and extension of bullae, epithelial defects, and persistence of amniotic membrane, were obtained at days 4 and 14, and months 1, 2, 4 and 6 after surgery.

RESULTS

No pain, bullae or epithelial defects were present at day 14 in any patient. However, progressive dissolvement of the amniotic membrane was accompanied with more bullae and pain. At 6th month, 4 of 5 patients required bandage contact lens.

CONCLUSION

Amniotic membrane transplantation alleviates short-term symptomatic bullous keratopathy and preserves corneal anatomy. Six months after surgery, anatomical and symptomatic improvement does not avoid the need of bandage contact lens.

Mechanisms involved in the increase in intracellular calcium following hypotonic shock in bovine articular chondrocytes

The extracellular osmotic environment of chondrocytes fluctuates during joint loading as fluid is expressed from and reimbibed by the extracellular matrix. Matrix synthesis by chondrocytes is modulated by joint loading, possibly mediated by variations in intracellular composition. The present study has employed the Ca2+-sensitive fluoroprobe Fura-2 to determine the effects of hypotonic shock (HTS) on intracellular Ca2+ concentration ([Ca2+]i) and to characterise the mechanisms involved in the response for isolated bovine articular chondrocytes. In cells subjected to a 50% dilution, [Ca2+]i rapidly increased by approximately 250%, a sustained plateau being achieved within 300 s. The effect was inhibited by thapsigargin or by removal of extracellular Ca2+, indicating that the rise in [Ca2+]i reflects both influx from the extracellular medium and release from intracellular stores. Inhibition of the response by neomycin implicates activation of PLC and IP3 synthesis in the mobilisation of Ca2+ from intracellular stores. The rise was insensitive to inhibitors of L-type voltage-activated Ca2+ channels (LVACC) or reverse mode Na+/Ca2+ exchange (NCE) but could be significantly attenuated by ruthenium red, an inhibitor of transient receptor potential vanilloid (TRPV) channels and by Gd3+, a blocker of stretch-activated cation (SAC) channels. The HTS-induced rise in [Ca2+]i was almost completely absent in cells treated with Ni2+, a non-specific inhibitor of Ca2+ entry pathways. We conclude that in response to HTS the opening of SACC and a member of TRPV channel family leads to Ca2+ influx, simultaneously with the release from intracellular stores.

Effects of hypotonic shock on intracellular pH in bovine articular chondrocytes

Chondrocytes inhabit an unusual environment, in which they are repeatedly subjected to osmotic challenges as fluid is expressed from the extracellular matrix during static joint loading. In the present study, the effects of hypotonic shock on intracellular pH, pH(i), have been studied in isolated bovine articular chondrocytes using the pH-sensitive fluroprobe BCECF. Cells subjected to a 50% dilution rapidly alkalinised, by approximately 0.2 pH units, a sustained plateau being achieved within 300 s. The effect was not altered by inhibitors of pH regulators, such as amiloride, bafilomycin and SITS, but was absent when cells were subjected to hypotonic shocks in solutions in which Na(+) ions were replaced by NMDG(+). The response was found to be sensitive to Gd(3+) ions, blockers of stretch-activated cation channels. Alkalinisation was also inhibited by treatment with Zn(2+) ions, at a concentration reported to block voltage-activated H(+) channels (VAHC). Depolarisation using high K(+) solutions supplemented with valinomycin also induced intracellular alkalinisation. Measurements using a membrane potential (E(m)) fluorescent dye showed that E(m) was approximately -44 mV, but was depolarised by over 50 mV following HTS. The depolarisation was also inhibited by Na(+) substitution with NMDG(+) or treatment with Gd(3+). We conclude that in response to HTS the opening of a stretch-activated cation channel leads to Na(+) influx, which results in a membrane depolarisation. Subsequent activation of VAHC permits H(+) ion efflux along the prevailing electrochemcial gradient, leading to the alkalinisation, which we record.

[Analytic management in ophthalmology: towards a cost per hospital out- and in-patient]

PURPOSE

To determine the total annual cost of the activities in the Ophthalmology Department at the Hospital La Mancha-Centro, Homogeneous functional group (HFG) of the INSALUD, and to estimate the cost per patient/process of both ambulatory patients and hospital in-patients.

METHODS

The study was designed over 1 year period, from January to December 1997, and applied by using analytic accounting in 17,857 patients seen at the out-patient ophthalmology clinic and 973 hospital in-patients who were classified by diagnosis-related groups (DRG) and sorted out by analysis of Case Mix index.

RESULTS

We have determined the annual cost of our activity in both the ambulatory patient group and the hospital in-patient group classified by DRG and obtained the cost per process.

CONCLUSIONS

To know systematically the annual cost of our medical and surgical activity is nowadays a necessary tool in the framework of the Total Quality Plan developed by the INSALUD's SIGNO Group since 1991. This leads us to the analytic management area and places us in the never ending search for the ideal model of cost per process determination.

[Subconjunctival mitomycin C for the treatment of ocular cicatricial pemphigoid]

PURPOSE

We study the efficacy of treating ocular cicatricial pemphigoid (OCP) with subconjuctival mitomycin C (MMC).

METHODS

The patients were eligible for treatment under two criteria: 1. Significant complications of systemic immunosuppressant therapy. 2. Avanced stage of OCP. All patients received an injection of 0.25 ml of 0.2 mg/ml mitomycin C to both the upper and lower bulbar conjunctiva in both eyes.

RESULTS

Four patients were treated with subconjunctival mitomycin C (both eyes) and were followed for an average of 17 months (range 9-26 months). Three of four patients showed progression of the conjunctival disease and required concomitant systemic immunosuppressive therapy after subconjuctival mitomycin C.

CONCLUSION

No complications of subconjunctival mitomycin C treatment were noted but, contrary to what other authors had referred, its use was not effective in preventing progression of conjunctival cicatrization in our patients with OCP.

Secretion of human interferon alpha 2b by Streptomyces lividans

Biologically active human interferon alpha 2b (HuIFNalpha-2b) was secreted into the culture medium by Streptomyces lividans transformed with recombinant plasmids coding for HuIFNalpha-2b fused to the Streptomyces exfoliatus M11 lipase A signal sequence. Levels were low, 15 or 100 ng/ml, depending on the plasmid used. Neither processed nor unprocessed HuIFNalpha-2b was detected in cell lysates of the transformants secreting the recombinant product. However, the secreted recombinant product was found to partially degrade when cultures reached the stationary phase by the action of an, as yet, unidentified mycelium-associated factor. Experimental evidence suggests that the degrading factor is related to mycelium-associated proteolytic activity.

[Cardiorespiratory arrest: a rare complication of subdural block]

We report a case of accidental subdural block after epidural anesthesia that manifested as cardiac arrest due to extensive spinal blockade 20 minutes after administration of 50 mg of 0.5% bupivacaine. The event resolved without sequelae. Subdural placement of the catheter was verified by computed axial tomography contrast medium. Clinical signs of subdural block are highly variable, extensive neural block being among the possible rare presentations, with latency ranging from a few minutes to as long as 30. Recent electron microscope observations with new methods for fixing and preparing tissues suggest that the dubdural space does not exist naturally, but rather forms artificially within a low-resistance cell plane composed of neurothelial cells, as a result of trauma or the injection of a local anesthetic. The characteristics of the space depend, therefore, on factors that come together at the site. These data explain the great variability in the clinical manifestations of a subdural block. The case of cardiopulmonary arrest we report is rare in the literature.

[Bilateral serous retinal detachments in acute posterior multifocal placoid pigmentous epitheliopathy]

PURPOSE/METHOD

A particular subtype of acute posterior multifocal placoid pigmented epitheliopathy (APMPPE), different from the classical Gass description, is presented. A 22 year old woman who suffered a sudden decrease in visual acuity associated to bilateral serous retinal detachment concurrent with anterior uveitis is studied. We remark the fact that patient had been using contraceptives and antibiotics (norfloxacin) for the past two months prior to first visit. One month later, visual acuity does not show any recovery. A corticosteroid treatment is prescribed showing improvement.

RESULTS/CONCLUSIONS

We believe that although APMPPE usually resolves spontaneously, treatment is needed for clinical subtypes involving serous retinal detachment.

Action of ebrotidine, ranitidine and cimetidine on the specific binding to histamine H1- and H2-receptors

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)-4-thiazolyl]methyl]thio] ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542), a selective H2-receptor antagonist, has proved to competitively inhibit the positive chronotropism induced by histamine in isolated guinea pig atrium. The affinity of ebrotidine to histamine H1- and H2-receptors through the displacement of 3H-pyrilamine and 3H-thiotidine binding to guinea pig cerebellum and brain cortex membranes was investigated. Ebrotidine displaced 3H-thiotidine specific binding to histamine H2-receptors (Ki: 127.5 nmol/l), showing a higher affinity (p < 0.05) than ranitidine (Ki: 190.0 nmol/l) and cimetidine (Ki: 246.1 nmol/l). None of the three substances displaced 3H-pyrilamine binding to H1-receptors (Ki: > 5000 nmol/l). The results showed that ebrotidine is a drug with a high affinity for H2 receptors, higher than cimetidine and ranitidine.

Activation of a cryptic gene encoding a kinase for L-xylulose opens a new pathway for the utilization of L-lyxose by Escherichia coli

A silent gene encoding a kinase that specifically phosphorylates L-xylulose was activated and rendered constitutive in mutant cells of Escherichia coli. L-Xylulose kinase was purified to homogeneity and found to be a dimer of two subunits of 55 kDa, highly specific for L-xylulose with a Km of 0.8 mM, a Vmax of 33 mumol/min/mg, and an optimum pH of 8.4. Physical (thin layer chromatography) and spectroscopic (nuclear magnetic resonance and optical rotation) characterization of the product of L-xylulose kinase indicated that the enzyme phosphorylated the sugar at position 5. The gene encoding L-xylulose kinase was mapped in the 80.2 min region of the chromosome by conjugation and transduction. Cloning and comparison of the restriction map with the Kohara map (Kohara, Y., Akiyame, K., and Isono, K. (1987) Cell 50, 495-501) located the gene between positions 3963 and 3965 kilobases. The molecular and functional features of L-xylulose kinase together with the location of the corresponding gene indicate that this enzyme did not derive from mutation of any other known kinase. The new kinase opens a route for the utilization of L-lyxose through the action of rhamnose permease, rhamnose isomerase, and the phosphorylation of the L-xylulose formed to L-xylulose 5-phosphate, which is then introduced into the pentose phosphate pathway for subsequent metabolism.

[Evaluation of 2 serological techniques in the diagnosis of neurocysticercosis: complement fixation reaction and Western blot]

Evaluation of two serological techniques for diagnosis cysticercosis: complement fixation reaction and Western blot. Comparative study that includes 49 sera samples and 30 CSF samples belonging to 35 patients with clinical diagnosis of cysticercosis of the CNS. As a control group we used 10 sera samples of patients with Trichinella spiralis infection, 33 sera samples of patients with hydatid cyst disease, 9 sera samples from patients with oxyuriasis, 52 sera samples of healthy blood donors and 22 additional CSF samples from patients with different CNS disorders. Thirty-one samples were positive by Western blot technique and 21 samples by complement fixation reaction technique. Agreement between both techniques was 76%. Gathering clinical and laboratory information we believe that a total of 11 patients had cysticercosis of the CNS (33 samples), and three additional patients remain with indeterminate diagnosis. We have also detected cross-reactions with Western blot techniques (reactivity to more than one band) in 43% of patients with hydatid disease and in 20% of patients with Trichinella spiralis infection, but none in oxyuriasis patients. The CFR technique had cross-reaction with 33% of sera samples from hydatid disease patients and 20% of those from oxyuriasis patients. No cross-reactions were seen in any of control patients with both techniques. The two different techniques tested can be of help, together with clinical and radiology data, in the diagnosis of cysticercosis of the CNS. However, both techniques showed strong cross-reactions with hydatid disease.

[Brucellosis and acute inflammatory polyradiculoneuropathy]

Three patients with Guillain-Barré syndrome (GBS) during active brucellosis are reported: in one of them, who had an unfavorable outcome, the clinical features, the neurophysiological studies and the sural nerve biopsy were consistent with the axonal form of GBS. In the remaining two patients, who had a satisfactory course, the neurophysiological studies and the sural nerve biopsy disclosed the demyelinating character of the disease. We agree with other authors that the axonal and demyelinating forms of GBS should be separated, in view of their different clinical and possibly pathogenetic implications, both in GBS in general and in the form associated with brucellosis.