Nanoscale Dynamics of Streptococcal Adhesion to AGE-Modified Collagen

The adhesion of initial colonizers such as Streptococcus mutans to collagen is critical for dentinal and root caries progression. One of the most described pathological and aging-associated changes in collagen-including dentinal collagen-is the generation of advanced glycation end-products (AGEs) such as methylglyoxal (MGO)-derived AGEs. Despite previous reports suggesting that AGEs alter bacterial adhesion to collagen, the biophysics driving oral streptococcal attachment to MGO-modified collagen remains largely understudied. Thus, the aim of this work was to unravel the dynamics of the initial adhesion of S. mutans to type I collagen in the presence and absence of MGO-derived AGEs by employing bacterial cell force spectroscopy with atomic force microscopy (AFM). Type I collagen gels were treated with 10 mM MGO to induce AGE formation, which was characterized with microscopy and enzyme-linked immunosorbent assay. Subsequently, AFM cantilevers were functionalized with living S. mutans UA 159 or Streptococcus sanguinis SK 36 cells and probed against collagen surfaces to obtain force curves displaying bacterial attachment in real time, from which the adhesion force, number of events, Poisson analysis, and contour and rupture lengths for each individual detachment event were computed. Furthermore, in silico computer simulation docking studies between the relevant S. mutans UA 159 collagen-binding protein SpaP and collagen were computed, in the presence and absence of MGO. Overall, results showed that MGO modification increased both the number and adhesion force of single-unbinding events between S. mutans and collagen, without altering the contour or rupture lengths. Both experimental and in silico simulations suggest that this effect is due to increased specific and nonspecific forces and interactions between S. mutans UA 159 and MGO-modified collagen substrates. In summary, these results suggest that collagen alterations due to aging and glycation may play a role in early bacterial adherence to oral tissues, associated with conditions such as aging or chronic hyperglycemia, among others.

Isolation and characterization of Clostridium difficile from a small survey of wastewater, food and animals in New Zealand

The objective of this study was to undertake a microbiological survey of foods, animal faeces and wastewater samples for Clostridium difficile, and determine the genotypes and antimicrobial susceptibilities of isolates. A total of 211 samples were tested for C. difficile using culture methods. Thirteen toxigenic C. difficile isolates were obtained; ten from wastewater samples, one each from pig and duck faeces and another from a raw meat product. Eight PCR-ribotypes (RTs) were identified, including two novel RTs (878 and 879). Single-nucleotide polymorphism analysis using WGS data for all isolates provided greater discrimination between C. difficile isolates within the same RT and multilocus sequence typing (MLST) profiles. All C. difficile isolates were found to be susceptible to the first-line human antimicrobials used to treat C. difficile infection. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to report the isolation of Clostridium difficile from animals, food and wastewater in New Zealand (NZ) and provides important data with respect to ribotypes and multilocus sequence typing profiles, whole genome sequence and antimicrobial susceptibilities. The results highlight the need for further investigations into the epidemiology of C. difficile in NZ and to elucidate the role of the environmental and food sources as transmission routes of human infection.

The Association of Conjunctival Snake-Like Chromatin with Keratoconjunctivitis Sicca

Purpose

This work describes the snake-like chromatin cells in the conjunctiva of patients with keratoconjunctivitis sicca (KCS), assessing the relationship between tear function parameters and the severity of the disease, and searching for any differential pattern that could lead to early and diagnosis help clarify the etiology of KCS.

Methods

The conjunctiva of 366 eyes from 187 patients with KCS, and 30 eyes from 15 controls, were classified according to the results of the Schirmer I test, break-up time, rose Bengal staining, osmolarity, ferning tests and electrophoresis; they were then studied by impression cytology and electron microscopy.

Results

Snake-like chromatin cells, other nuclear changes, and a decreased number of goblet cells were found by impression cytology in different areas of the KCS conjunctiva. The presence of snake-like chromatin was significantly correlated with the severity of the disease. No nuclear changes were found in the control group.

Conclusions

We assume these findings can be attributed to a natural regeneration of conjunctival cells and to resistance to a pathological reaction to KCS.

Ultrastructural Study of the Conjunctiva in Patients with Keratoconjunctivitis Sicca not Associated with Systemic Disorders

Purpose

The aim of this work was to evaluate ultrastructural alterations of the conjunctiva during the clinical course of keratoconjunctivitis sicca (KCS), and to detect its earliest and most characteristic morphological changes.

Methods

The conjunctiva was studied in biopsies from 75 patients and 10 controls. Patients were classified according to the results of the Schirmer I test, break-up time, rose Bengal staining, osmolarity and impression cytology.

Results

The conjunctiva in these KCS patients showed progressive hyperplasia, hypertrophy and cellular flattening, with diminution of goblet cell density and microvilli. In the severe cases, the epithelial cells lost their organelles, and fibrous material increased. From the early phases of KCS, clear nuclear alterations (indentation, binucleation) were found, but pyknotic nuclei or anucleated cells were only observed in the most severe cases. From the earliest stages to the most severe cases of KCS, decreases in cell membrane interdigitations were observed parallel to increases in the number and size of desmosomes. There were also increases in the number of inflammatory cells. Alterations in blood vessels were only observed in the most severe cases.

Conclusions

Morphological studies alone were able even in the earliest phases of KCS, to detect the squamous metaplasia that progresses from the surface of the epithelium to the connective tissue. This degenerative or adaptative cellular process was characterized mainly by marked proliferation of the cytoskeleton and a general loss of organelles, mitochondria being the least affected.

Parotid Salivary Gland Basal Cell Adenocarcinoma in a Big-eared Opossum (Didelphis aurita)

The opossum (family Didelphidae) is a marsupial endemic to the Americas. Apart from the South American short-tailed opossum (Monodelphis domestica) and the Virginia opossum (Didelphis virginiana), there is considerable lack of knowledge about the health and diseases of most opossum species. Among these, the big-eared opossum (Didelphis aurita) is found in Argentina, Brazil and Paraguay. Natural and experimental studies have shown this species to be susceptible to infectious agents with zoonotic potential and the animals may play a role in transmission of such agents. However, neoplasia appears to be uncommon in this species. We describe the gross, microscopical and immunohistochemical features of a parotid salivary gland basal cell adenocarcinoma in a free-living big-eared opossum. This case represents the first report of salivary gland neoplasia in opossums.

Microbial competition in environmental nosocomial reservoirs and diffusion capacity of OXA48-Klebsiella pneumoniae: potential impact on patients and possible control methods

BACKGROUND

We have found clusters of Klebsiella pneumoniae with OXA48-carbepenemase cases in some hospital rooms, and decided to investigate whether bathroom siphons could be a reservoir for OXA48 bacteria, as occurs with K. oxytoca with other types of carbepenemases.

METHODS

We evaluated the microbial competition between strains with OXA48 and VIM carbepenemases, in diluted nutrient-broth, on a slime germ-carrier. We compared the number of colonies at 5 and 10 days on the contaminated carriers with one or two strains. We evaluated the dissemination of K. pneumoniae with carbepenemase OXA48 or VIM from thumbs and index fingers of volunteers, to standard surfaces (20 glass germ-carrier by each volunteer). After, we counted the number of microorganisms on each carrier. Microbiological weekly studies of faecal microbiota of all patients were obtained in Traumatology and Oncology. Moreover, we studied samples of the sink in their rooms. PCR and MLST sequence-type was determined in all K. pneumoniae diagnosed from patients and sinks.

RESULTS

A large possibility of diffusion from contaminated hands, which continue to transmit high numbers of microorganisms after more than 10 successive surface contacts, was highlighted; OXA bacteria were more persistent than VIM bacteria. Microbial competition studies showed that VIM bacteria are inhibited by OXA ones. These observations can explain the concentration of cases of K. pneumoniae OXA48 in some rooms in Traumatology and Oncology, producing a significant OR between rooms with OXA48-bacteria-contaminated siphons and other rooms (3.1 and 3.3 respectively). Risk was lowered after changing or disinfecting (heat plus chlorinated disinfectant) the contaminated siphons. Siphon colonization by VIM bacteria was not related with human infections by similar microorganisms.

CONCLUSIONS

Bathroom siphons can be a reservoir for K. pneumoniae OXA48 and lead to outbreaks. Outbreaks can be controlled by replacement or heat plus chemical treatment of the sink-siphons.

A DNA Aptasensor for Electrochemical Detection of Vascular Endothelial Growth Factor

Electrochemical aptasensors can detect different cancer biomarkers to provide point-of-care diagnosis that is low cost, rapid, specific and sensitive. In this work, we described the development of an electrochemical single-use aptasensor for detection and analysis of vascular endothelial growth factor (VEGF). Gold nanostructured graphite screen-printed electrodes were firstly modified with a mixed monolayer of a primary thiolated DNA aptamer and a spacer thiol, 6-mercapto-1-hexanol. VEGF protein was then incubated with the aptasensor. An enzyme-amplified detection scheme, based on the coupling of a streptavidin-alkaline phosphatase conjugate and secondary biotinylated aptamer was then applied. The enzyme catalyzed the hydrolysis of the electroinactive 1 -naphthyl-phosphate to 1 -naphthol; this product is electroactive and has been detected by means of differential pulse voltammetry (DPV). The aptasensor response was found to be linearly related to the target concentration between 0 and 250 nmol L(-1); the detection limit was 30 nmol L(-1). The performance of the immunoassay in terms of reproducibility and selectivity has been also studied.

[Characterization of epithelial primary culture from human conjunctiva]

OBJECTIVE

To evaluate primary cultures from human conjunctiva supplemented with fetal bovine serum, autologous serum, and platelet-rich autologous serum, over human amniotic membrane and lens anterior capsules.

METHODS

One-hundred and forty-eight human conjunctiva explants were cultured in CnT50(®) supplemented with 1, 2.5, 5 and 10% fetal bovine serum, autologous serum and platelet-rich autologous serum. Conjunctival samples were incubated at 37°C, 5% CO2 and 95% HR, for 3 weeks.

RESULTS

The typical phenotype corresponding to conjunctival epithelial cells was present in all primary cultures. Conjunctival cultures had MUC5AC-positive secretory cells, K19-positive conjunctival cells, and MUC4-positive non-secretory conjunctival cells, but were not corneal phenotype (cytokeratin K3-negative) and fibroblasts (CD90-negative).

CONCLUSIONS

Conjunctiva epithelial progenitor cells were preserved in all cultures; thus, a cell culture in CnT50(®) supplemented with 1 to 5% autologous serum over human amniotic membrane can provide better information of epithelial cell differentiation for the conjunctival surface reconstruction.

Efficacy of cecropin A-melittin peptides on a sepsis model of infection by pan-resistant Acinetobacter baumannii

Pan-resistant Acinetobacter baumannii have prompted the search for therapeutic alternatives. We evaluate the efficacy of four cecropin A-melittin hybrid peptides (CA-M) in vivo. Toxicity was determined in mouse erythrocytes and in mice (lethal dose parameters were LD(0), LD(50), LD(100)). Protective dose 50 (PD(50)) was determined by inoculating groups of ten mice with the minimal lethal dose of A. baumannii (BMLD) and treating with doses of each CA-M from 0.5 mg/kg to LD(0). The activity of CA-Ms against A. baumannii was assessed in a peritoneal sepsis model. Mice were sacrificed at 0 and 1, 3, 5, and 7-h post-treatment. Spleen and peritoneal fluid bacterial concentrations were measured. CA(1-8)M(1-18) was the less haemolytic on mouse erythrocytes. LD(0) (mg/kg) was 32 for CA(1-8)M(1-18), CA(1-7)M(2-9), and Oct-CA(1-7)M(2-9), and 16 for CA(1-7)M(5-9). PD(50) was not achieved with non-toxic doses (≤ LD(0)). In the sepsis model, all CA-Ms were bacteriostatic in spleen, and decreased bacterial concentration (p < 0.05) in peritoneal fluid, at 1-h post-treatment; at later times, bacterial regrowth was observed in peritoneal fluid. CA-Ms showed local short-term efficacy in the peritoneal sepsis model caused by pan-resistant Acinetobacter baumannii.

Autologous Serum Eyedrops in the Treatment of Aniridic Keratopathy

OBJECTIVE

To study the effect of autologous serum eyedrop application in aniridic keratopathy.

DESIGN

Prospective, consecutive, comparative, interventional case series.

PARTICIPANTS

Twenty-six eyes from 13 patients (7 males and 6 females) with aniridic keratopathy treated with autologous serum eyedrops.

METHODS

All patients underwent a complete ophthalmic examination. The ocular surface examinations included corneal impression cytologic analysis and tear film evaluation. The eyes were divided into 4 groups according to the Mackman classification. Ocular surface photography was used to evaluate the corneal surface and tear film before treatment and every 2 or 3 days until serum drops were stopped. Tear films were evaluated by tear film break-up time (BUT) (normal, 10 seconds or more), Schirmer's test with anesthesia (normal, 10 mm/5 minutes or more), tear meniscus level (normal, 0.5 mm or more), and rose bengal and fluorescein staining pattern of the cornea. Impression cytologic analysis was carried out both before starting the serum eyedrops treatment and a few days after its finalization.

MAIN OUTCOMES MEASURES

Tear film production and stability, corneal epithelialization, and corneal epithelium squamous metaplasia.

RESULTS

There were no local side effects from autologous serum treatment. Clinical manifestations and slit-lamp findings were in relation to the severity of keratopathy. All patients showed a subjective improvement of keratopathy symptoms after the autologous serum applications. The corneal epithelialization, corneal epithelial cell squamous metaplasia, and tear stability improved significantly with the treatment, but visual acuity, regression of vascular pannus, and subepithelial scarring showed only slight improvement with treatment.

CONCLUSIONS

Autologous serum eyedrops improved the aniridic keratopathy in all patients, particularly in patients with light or moderate severity. In these patients, use of autologous serum eyedrops was superior to conventional therapy with substitute tears for improving the ocular surface and subjective comfort.

[Use of autologous serum in ophthalmic practice]

OBJECTIVE

To establish a protocol for the use of autologous serum in the ophthalmic practice.

METHODS

Personal experience and a literature review.

RESULTS

The use of autologous serum, in eye drop form, has been reported as a new treatment for several ocular surfaces diseases. These products have biomechanical and biochemical properties similar to normal tears. They contain components such as fibronectin, vitamin A and growth factors that have an epitheliotrophic effect on the ocular surface epithelial cells.

CONCLUSIONS

The clinical studies performed showed a variable efficacy, with the preparative process and use of the autologous serum eye drops varying considerably between different studies.

Different conjunctival adaptive response in patients with aqueous-deficient and with mucous-deficient dry eyes

PURPOSE

To describe the different cellular adaptive patterns found in the conjunctival epithelium from patients with aqueous-deficient and mucous-deficient dry eyes.

METHODS

The authors studied different conjunctival areas, by impression cytology and by biopsy, 50 eyes with facial nerve paralysis (FNP), 50 eyes with ocular cicatricial pemphigoid (OCP), and 50 eyes from patients with primarily Sjögren syndrome (1SS).

RESULTS

Eyes with FNP from the first clinical grade showed a progressive alteration of the nonsecretory cells, with a significant decrease in density goblet cells, generally with a PAS-positive staining. Eyes with OCP, during clinical grades 1 and 2, showed a slow deterioration of the nonsecretory cells; but from clinical grade 3, there was a significant increase of the cellular size and the thickness of the conjunctiva. Goblet cells showed a significant decrease in density from clinical grade 1, generally with a PAS-negative staining. Eyes with 1SS during clinical grades 1 and 2 showed a progressive alteration of the nonsecretory cells, with a significant decrease in density goblet cells, and a PAS-positive staining. From clinical grade 3 appeared a significant increase of nonsecretory cellular size and thickness of conjunctiva, with a significant decrease in goblet cell counts, and a PAS-negative staining.

CONCLUSIONS

Patients with FNP (a primarily aqueous-deficient alteration) follow completely the squamous metaplasia process. Patients with OCP (a primarily mucous-deficient syndrome) have a hypertrophy and hyperplasia process along the ocular surface. Patients with 1SS (a primarily aqueous-deficient and mucin-deficient alteration) have a squamous metaplasia process, but from clinical grade 3 also appears a hypertrophy and hyperplasia process.

Influence of deep scleral flap size on intraocular pressure after deep sclerectomy

PURPOSE

To study the effect of several morphometric characteristics of the deep scleral flap on intraocular pressure (IOP) control after deep sclerectomy.

METHODS

The authors conducted a nonrandomized prospective study of 56 eyes of 51 patients who underwent deep sclerectomy alone or combined with phacoemulsification. A reticulated hyaluronic acid implant was used in all cases. The surface, volume, and weight of the dissected deep scleral flap were measured and recorded. The correlation between these parameters and the postoperative IOP was evaluated at 6 and 12 months postoperatively.

RESULTS

Forty-nine eyes (87.50%) achieved an IOP of 21 mmHg or less without treatment, and the need for medication was decreased significantly (p<0.001) at 12 months postoperatively. The authors found a significant inverse correlation between the mean postoperative IOP at 6 months and the surface, volume, and weight of the deep scleral flap, but not at 12 months postoperatively.

CONCLUSIONS

Greater weight, surface area, and volume of the deep scleral flap dissected during deep sclerectomy achieve significantly lower postoperative IOPs in the early postoperative period.

[Congenital aniridia keratopathy treatment]

OBJECTIVE

To attempt to review the aniridia keratopathy pathogenesis and establish a treatment protocol according to the severity of the symptoms.

METHODS

Personal experience in aniridic keratopathy management and a bibliography review.

RESULTS

The ocular manifestations of this anomaly include defects of the cornea, glaucoma, lens subluxation, cataracts, hypoplasia of the iris, fovea and optic nerve, amblyopia and nystagmus. The keratopathy occurs in a 20% of patients with aniridia. The correct PAX6 expression is necessary for normal corneal development, limbal stem cell activity and correct corneal epithelial cell migration and adhesion.

CONCLUSIONS

The management of ocular surface diseases due to limbal stem cell deficiency in aniridia is complex but has changed in recent years, as an understanding of the limbal stem cells and their microenvironment has modified the therapeutic approach. The use of autologous serum eye drops, amniotic membrane transplantation, limbal transplantation or cultivated limbal cell transplantation have all been reported as a treatment for several ocular surface diseases.

Analysis of Corneal Surface Evolution After Moderate Alkaline Burns by Using Impression Cytology

PURPOSE

To compare corneal surface evolution after moderate alkaline burns by impression cytology in patients treated with medical therapy or with amniotic membrane transplantation (AMT).

METHODS

A prospective study of 24 eyes from 18 patients (13 men and 5 women) with moderate alkaline burns was performed. All patients were divided according to the clinical ocular severity and the therapy used. Twelve eyes were treated surgically with AMT and the other 12 eyes received only medical therapy. Corneal cytology was obtained immediately after the burns, and 1, 2, 5, and 9 months later. We differentiated between samples obtained from affected areas and areas not affected by the burns. Cellular size, nuclear size, and nuclear-cytoplasmic (N:C) ratio were examined in corneal epithelial cells, as was the presence of goblet cells in corneal epithelium.

RESULTS

Nuclear size, cellular size, and N:C ratio in non-burn-affected corneal areas had no significant alterations in comparison with normal eyes. In contrast, in burn-affected corneal areas, these parameters were significantly worse, and the presence of goblet cells in corneal epithelium was frequent 1 month after severe burns. Cellular size, nuclear size, N:C ratio, and corneal conjunctivalization improved during the study in all patients, but corneal reepithelialization occurred earlier in patients treated with AMT than in patients with only medical therapy.

CONCLUSION

Morphologic and morphometric analysis of corneal cells by impression cytology after ocular burns permits the establishment of cellular reepithelialization patterns in relation with limbal deficiency level and with clinical ocular severity. AMT improves corneal reepithelialization earlier than medical therapy in moderate alkaline burns.

[Corneal epithelium squamous metaplasia determination as diagnostic factor in limbal deficiency]

PURPOSE

To determine the correlation between the squamous metaplasia grade of the corneal surface and the clinical severity of the limbal deficiency in patients with this disorder.

METHODS

We studied 98 eyes of patients with limbal deficiency by impression cytology. These patients were divided into four groups in relation to their clinical severity: 14 eyes had no symptoms, 34 eyes showed a mild grade of limbal deficiency, 28 eyes had a moderate grade and 22 eyes had severe limbal deficiency. Corneal cytology was performed in each patient. Cellular size, nuclear size, nuclear changes and the nuclear-cytoplasmic (N:C) ratio were defined in corneal epithelial cells, in addition to evaluation for the presence of goblet cells in the corneal epithelium.

RESULTS

In patients with limbal deficiency without symptoms, we found that the cellular size was 477 (SD140) microm2 and the N:C ratio was 1:5.25 (SD1.5). In patients with mild limbal deficiency, the cellular size was 764 (SD122.6) microm2 and the N:C ratio was 1:8.2 (SD1.4). These patients did not show corneal conjunctivalization. In patients with moderate limbal deficiency the cellular size was 1,162 (SD340.2) microm2 and the N:C ratio was 1:13.2 (SD3.6). Some patients showed corneal conjunctivalization that was defined by the presence of goblet cells in the corneal epithelium. In patients with severe limbal deficiency, the cellular size was 2,036 (SD382) microm2 and the N:C ratio was 1:23.6 (SD4.0). Corneal conjunctivalization was present in all of these patients.

CONCLUSIONS

There was a correlation between limbal deficiency severity and squamous metaplasia grade defined by impression cytology. Impression cytology was very useful for the diagnosis of cases of mild or subclinical limbal deficiency.

Physicochemical properties of Shiga toxigenic Escherichia coli

AIMS

To investigate the physicochemical surface properties, such as cellular surface charge, hydrophobicity and electron donor/acceptor potential of a selection of Shiga toxigenic Escherichia coli (STEC) isolates grown in broth and agar culture.

METHODS AND RESULTS

Cellular surface charge was determined using zeta potential measurements. Hydrophobicity of the isolates was determined using bacterial adhesion to hydrocarbons assay, hydrophobic interaction chromatography and contact angle measurements. Microbial adhesion to solvents was used to determine the electron donor/acceptor characteristics. No differences of surface charge measurements were found between broth and agar grown cultures. Isolates belonging to serogroup O157 and serotypes O26:H11 and O111:H- were significantly (P < 0.05) less negatively charged than other STEC serotypes tested. All strains were hydrophilic with most methods and demonstrated a lower hydrophobicity in agar culture compared with broth culture. All strains demonstrated a strong microbial adhesion to chloroform indicating that STEC possess an electron donor and basic character. A relationship between serogroup O157 and other STEC serotypes was apparent using principal-component analysis (PCA).

CONCLUSIONS

Combining the results for physicochemical properties using PCA differentiated between strains belonging to the O157 serogroup and other STEC/non-STEC strains. PCA found similar results for broth and agar grown cultures.

SIGNIFICANCE AND IMPACT OF THE STUDY

Particular serotypes of STEC possess similar physicochemical properties which may play a role in their pathogenicity or potential attachment to various surfaces.

[Moderate limbal deficiency in patients with congenital aniridia treated with amniotic membrane transplantation]

PURPOSE

To study the ocular surface evolution by impression cytology and limbal biopsy in patients with congenital aniridia treated with amniotic membrane transplantation (AMT).

METHODS

We studied 14 eyes of patients with congenital aniridia and moderate limbal deficiency that were treated with AMT. The morphology of the limbocorneal epithelium and stroma was examined by impression cytology and limbal biopsy. Impression cytology was performed prior to surgery and 3, 6, 9, 12 and 24 months after treatment. Limbal biopsy was performed before surgery and 9 months after AMT.

RESULTS

Visual acuity showed a mean improvement of 0.3 at 24 months of follow-up. Corneal reepithelialization was completed by 2 months in all patients, however, after 9 months some patients showed persistent epithelial defects and chronic ulceration. Corneal clarity and peripheral neovascularization was markedly improved after 2 months. Impression cytology showed an improvement in squamous metaplasia at 3 and 6 months, however after nine months, until as late as 24 months, a progressive worsening was seen in epithelial cell metaplasia then being similar in extent to that before surgery. Limbal biopsy nine months after surgery showed a nearly normal epithelium and limbocorneal stroma.

CONCLUSIONS

AMT is a very effective procedure, although its effect is transitory, for restoring the ocular surface integrity in patients with congenital aniridia and moderate limbal deficiency.

[Severe limbal deficiency treated by combined limbal allograft and amniotic membrane transplantation]

PURPOSE

To study the ocular surface evolution in patients with severe limbal deficiency treated with limbal allograft transplantation (LT) combined with amniotic membrane transplantation (AMT).

METHODS

We studied 14 eyes with severe limbal deficiency, treated with LT combined with AMT (LT + AMT). We studied the morphology of the limbocorneal epithelium and stroma by impression cytology and limbal biopsy.

RESULTS

Visual acuity showed a mean improvement of 0.4 at 24 months of follow-up. Corneal clarity and loss of neovascularization were markedly improved after 3 and 6 months, respectively. We did not find corneal conjuntivalization on cytology performed 6 months after surgery, except in a patient with chemical burn. Cytology and limbal biopsy performed nine months after surgery showed an epithelium and limbocorneal stroma near to normality. Squamous metaplasia was worse in patients with Stevens-Johnson syndrome and ocular cicatricial pemphigoid after 12 months, but was similar in patients with chemical burns and improved in patients with aniridia.

CONCLUSIONS

LT + AMT is a very effective procedure for restoring the ocular surface integrity in patients with severe limbal deficiency. This combination improves the outcomes obtained with LT alone.

Safety and efficacy of antimicrobial peptides against naturally acquired leishmaniasis

Leishmaniases, which are important causes of morbidity and mortality in humans and dogs, are extremely difficult to treat. Antimicrobial peptides are rarely used as alternative treatments for naturally acquired parasitic diseases. Here we report that the acylated synthetic antimicrobial peptide Oct-CA(1-7)M(2-9) is safe and effective for treating naturally acquired canine leishmaniasis.

[The contribution of impression cytology towards the diagnosis of cicatricial ocular pemphigoid in its primary stages]

PURPOSE

To study the conjunctival epithelium by means of impression cytology in the cicatricial ocular pemphigoid (COP) in search of a possible relation between the degree of squamous metaplasia and clinical severity of the disease, in order to facilitate the earliest possible diagnosis.

METHODS

Impression cytology specimens were collected from 20 patients with varying degrees of active COP. A clinical ophthalmologic examination was performed by biomicroscopy, impression cytology, conjunctival biopsy, study of direct (IFd) and of indirect immunofluorescence (IFi).

RESULTS

Patients with COP grade I had a normal distribution of non-secretory epithelial cells with a decrease in goblet cell density of around 85% compared to control and mucin content was decrease. Patients with grade II showed a slight degree of squamous metaplasia. Goblet cell density decreased by around 95% and mucin content was scarce. Patients with clinical grade III had a moderate degree of squamous metaplasia in non-secretory cells whilst goblet cell density decreased by around 99%; mucin content was almost zero. Patients with clinical grade IV showed a moderate to severe degree of squamous metaplasia in non-secretory cells; there was a total absence of goblet cells.

CONCLUSIONS

Conjunctival impression cytology in COP showed a significant decrease in goblet cells from the early stages of disease without significant alterations in non-secretory epithelial cells. In patients with negative IFd impression cytology could enable the identification of a possible COP.

[Impression cytology study of dry eyes in patients with congenital aniridia]

PURPOSE

To evaluate the long-term results of ocular surface reconstruction by means of medical treatment, limbal transplantation or amniotic membrane transplantation in patients with congenital aniridia.

MATERIAL AND METHODS

Thirty-six eyes from 18 consecutive patients with aniridia were studied by clinical tests (Schirmer test, break-up time and vital rose bengal staining) and impression cytology. Thirteen patients were treated with lubricant drops for ocular dryness. Two eyes from 2 patients also received limbal transplantation, and other 4 eyes underwent amniotic membrane transplantation.

RESULTS

Corneal and conjunctival epithelium improved in all patients treated with lubricant drops. Ocular surface epithelium condition was worse in those patients not receiving artificial tears. After 12 months of limbal transplantation, clinical and morphological results showed a significant corneal recovery of at least two grades of squamous metaplasia in comparison with the previous situation. We also carried out amniotic membrane transplantation in patients with aniridia. The improvement was initially observed after 2 months and by the sixth month there was a significant improvement in clinical signs and symptoms, with normal corneal cells next to altered ones.

CONCLUSIONS

All the aniridic patients showed dry eye. Treatment with lubricant drops is necessary to decrease the squamous metaplasia process. Limbal transplantation and amniotic membrane implantation are needed for effective corneal surface reconstruction in patients with aniridia, which is followed by a significant improvement of the dry eye.

Biopsy of the conjunctiva in dry eye patients establishes a correlation between squamous metaplasia and dry eye clinical severity

PURPOSE

The aim of this work was to evaluate the different grades of squamous metaplasia of the conjunctiva during the clinical course of dry eye syndrome, detecting the most characteristic morphological and morphometric changes by biopsy in order to provide a diagnostic classification.

METHODS

The conjunctiva was studied under light microscopy by conventional histological methods and by morphometric analysis in 165 patients and in 33 controls. Patients were classified according to the Schirmer 1 test, break-up time, rose Bengal staining, osmolarity and impression cytology. The epithelium and connective tissue, with their different cells and other structures, were studied.

RESULTS

The conjunctiva in dry eye patients showed progressive stratification, hyperplasia, hypertrophy and cellular flattening, with loss of goblet cell density and mucous layer. We found five pathological grades of squamous metaplasia and one normal grade. Clear nuclear alterations (indentation and binucleation) were found in the early grades of dry eye syndrome, but pyknotic nuclei and anucleated cells were only seen in the most severe grades. The smallest epithelial cells were found in the control group and their size increased with the severity of the dry eye syndrome. From the earliest stages to the most severe cases, increases in cellular separation were observed. There was also an increase in the number of inflammatory cells. Blood and lymphatic vessels showed alterations only in the most severe cases.

CONCLUSIONS

This is the first grading system proposed for biopsy evaluation of the ocular surface in dry eye patients. These morphological and morphometric studies alone were able, even in the earliest phases of dry eye, to detect the squamous metaplasia that progresses from the surface of the epithelium to the connective tissue. This degenerative or adaptative cellular process was characterized mainly by marked increases in the stratification, epithelial cellular size and a general loss of goblet cells.

Impression cytology on conjunctiva and cornea in dry eye patients establishes a correlation between squamous metaplasia and dry eye clinical severity

PURPOSE

To obtain deeper knowledge of the cellular transition in squamous metaplasia, and to look for a correlation between the clinical grade of severity of dry eye and the grade of squamous metaplasia of the corneal and conjunctival epithelium, studied by impression cytology.

METHODS

A total of 143 patients with dry eye disorders of different grades of clinical severity and 33 control subjects of matched age and sex were studied. Symptoms, clinical tests (including Schirmer test, slit-lamp examination, break-up time, rose Bengal staining, vanishing lacunar sulci, and neovascularization), and tear osmolarity were used to establish the diagnosis of dry eye. The subjects were classified into six clinical grades, grade 0 indicating normal and grades 1 to 5 progressively more severe dry eye. Impression cytology specimens were taken from the central cornea and different areas of the conjunctiva of one eye from all patients. A morphologic and morphometric study of the photographs obtained by light microscopy showed cell size, nuclear size, nuclear-cytoplasmic ratio (N:C) in nonsecretory epithelial cells, and density of goblet cells.

RESULTS

Morphometric and morphologic studies of the ocular surface cells indicated significant differences, mainly in cell sizes, nuclear alterations, and the N:C ratio, in nonsecretory epithelial cells of the conjunctiva and cornea, and in goblet cell densities from the conjunctiva, between the clinically normal eyes and those with the five grades of clinical severity of dry eye, with different degrees of squamous metaplasia.

CONCLUSIONS

A morphologic and morphometric analysis of the ocular surface from patients with dry eye obtained by impression cytology led us to draft a new grading system containing one normal level and five levels of squamous metaplasia. This new grading system is based on a significant decrease in the number of goblet cells with less periodic acid-Schiff-hematoxylin-positive staining, an increase in nonsecretory cell size, more marked cell separation, a lower N:C ratio, and an increase in nuclear alterations. The clinical severity of the dry eye correlates with these alterations.

[Innervation of the lachrymal gland in patients with primary Sjögren's syndrome. An immunohistopathological study]

PURPOSE

Histopathological parameters of the main lachrymal gland from patients with primary Sjögren's syndrome (SS1) were investigated, and the relation between morphological and immunohistochemical changes in the innervation of lachrymal gland in patients with SS1, as well as the immunopathological differences between SS1, non-autoimmune keratoconjunctivitis sicca (KCS) and controls were analysed.

METHODS

Lachrymal glands from patients with SS1, KCS and control subjects were biopsied and examined using standard transmission electron microscopic techniques and an immunohistochemical method (vasoactive intestinal polypeptide-VIP).

RESULTS

Moderate numbers of myelinated and non-myelinated nerve fibres were found in the connective tissue around lachrymal glands in patients with SS1. Non-myelinated nerve fibres made contact with glandular epithelium, myoepithelial cells, vascular endothelium, plasma cells and fibroblasts. Patients with non-immunological KCS had similar characteristics as SS1 in number and activity, showing a normal morphological pattern. Control subjects showed a higher number of active nerve fibres.

CONCLUSION

Main lachrymal gland from patients with SS1 were therefore definitively innervated with moderate activity and normal structures. The ultrastructural study demonstrated there were no statistical differences with respect to patients with non-autoimmune KCS. Immunohistochemical studies showed a similar VIP activity in lachrymal gland between patients with SS1 and KCS, but there was a significant decrease in the innervation activity with regard to control subjects. All this implies that the autoimmunological factor in patients with SS1 does not significantly affect the lachrymal gland innervation.

[Impression cytology contribution to differential diagnosis of Sjögren syndrome in the ophthalmological clinic]

PURPOSE

First, to assess the use of impression cytology, clinical and laboratory tests in the daily clinic for the early diagnosis of Primary Sjögren Syndrome (SS1), and second, to establish morphological differences between SS1, keratoconjunctivitis sicca (KCS) and healthy controls using impression cytology.

MATERIAL AND METHOD

The study comprised 35 patients suffering from primary Sjögren syndrome, same number of patients with keratoconjunctivitis sicca and normal healthy subjects. All groups underwent clinical tests (Schirmer's test, break-up time, and bengal rose staining), laboratory tests (tear protein pattern, tear osmolarity and serum immunoglobulin readings), and impression cytology on different areas of the conjunctiva and cornea.

RESULTS

All patients presented one or more subjective symptoms of ocular irritation although seeming normal at naked eye. Two patients with Sjögren's syndrome showed total corneal keratinization. Clinical and laboratory tests did not show significant differences between Sjögren's syndrome patients group and keratoconjunctivitis group. Serum tests of antibodies and immunoglobulins did present diagnostic values. Impression cytology showed significant differences between Sjögren syndrome patients compared to the rest of groups with regard to epithelial and goblet cells.

CONCLUSIONS

Impression cytology consists in a hystopathological test and it is considered the only ophtalmological test that offers a differential diagnosis in Sjögren's syndrome and should be included in a classification criteria. Inpression cytology presents significant differences between Sjögren syndrome and keratoconjunctivitis sicca.

N-terminal fatty acid substitution increases the leishmanicidal activity of CA(1-7)M(2-9), a cecropin-melittin hybrid peptide

In order to improve the leishmanicidal activity of the synthetic cecropin A-melittin hybrid peptide CA(1-7)M(2-9) (KWKLFKKIGAVLKVL-NH(2)), a systematic study of its acylation with saturated linear fatty acids was carried out. Acylation of the N(epsilon)-7 lysine residue led to a drastic decrease in leishmanicidal activity, whereas acylation at lysine 1, in either the alpha or the epsilon NH(2) group, increased up to 3 times the activity of the peptide against promastigotes and increased up to 15 times the activity of the peptide against amastigotes. Leishmanicidal activity increased with the length of the fatty acid chain, reaching a maximum for the lauroyl analogue (12 carbons). According to the fast kinetics, dissipation of membrane potential, and parasite membrane permeability to the nucleic acid binding probe SYTOX green, the lethal mechanism was directly related to plasma membrane permeabilization.

[Comparison of 2 lacrimal punctal occlusion methods]

PURPOSE

To study and compare two methods for canalicular occlusion: Cautery and Punctal Patch.

METHOD

The study included fourty patients divided in two groups of 20 patients. The end point was 4 occluded puncti. The first group underwent deep cauterization resulting in occlusion of the full vertical aspect of the canaliculus. The second group underwent punctal patch technique for canalicular occlusion. Differential parameters were the following: time of intervention, ease of use, risks and precision. In the post operatory, discomfort, subjective and objective improvement in ocular surface as well as long term result of each technique was analysed.

RESULTS

Time of intervention was longer for punctal patch compared to cautery. Both methods exhibited similar ease of use and improvement in ocular surface. Precision was high in punctal patch technique showing complete and final occlusion and no punctum needed reopening, while cautery technique presented 20% rate of reopening intervention. Postoperatory discomfort and irritation were remarkably evident with punctal technique, while minimal in cautery technique.

CONCLUSION

Survival analysis after one year follow up, showed a higher rate of advantages for punctal patch technique over cautery technique.

[Histopathological and immunohistochemical study of the ocular cicatricial pemphigoid]

OBJECTIVE

To study the relationship between the histopathological alterations and the clinical severity grade in the first phases of the ocular cicatricial pemphigoid to facilitate early diagnosis of the disease and initiate treatment as early as possible.

MATERIAL AND METHODS

We have studied 10 patients with different clinical grades of severity (3 patients with grade I; 4 patients with grade II; 2 patients with grade III, and 1 patient with grade IV). For these patients, full ophthalmologic examinations were performed [clinical, laboratory tests, impression cytology, ultrastructural study, study of direct (IFd) and indirect immunofluorescence (IFi).

RESULTS

The different techniques used have enabled us to observe the diminution of goblet cells, the initiation of subepithelial bullae, separation of epithelial basement membrane, increase and disorganization of collagen fibers, increase in the number of desmosomes, decrease in the number of hemidesmosones, increase in the intraepithelial fibrillar materials and the presence of immunoglobulin deposits and complement in the basement membrane of these patients in the early phases of the disease.

CONCLUSION

The techniques used in this study have enabled us to make an earlier diagnosis of the disease, since it manifests the eye dryness immediately and the posterior biopsy can confirm the differential diagnosis.

Measuring the lacunar sulci as a new indicator of shrinkage of the ocular surface

PURPOSE

To present a new indicator that measures the sulci of the lacrimal lake of the eye according to the degrees of ocular abduction at which they vanish. This new approach will help determine the severity and progression of mucosal retraction in ocular surface diseases.

METHODS

A total of 181 eyes of 94 healthy persons, 130 eyes of 65 patients with Sjogren's syndrome, and 30 eyes of 15 patients with ocular pemphigoid were examined using the slit lamp. We recorded the vanishing point of the three main lacunar sulci (plico-bulbar, plicocaruncular and dermo-caruncular) while abducting.

RESULTS

In healthy persons, the average vanishing points for the first and second lacunar sulci were respectively, 53.20 +/- 12.3 and 54.50 +/- 9.8. In patients with Sjogren's syndrome, 49.53 degrees +/- 10.81 and 53.17 degrees +/- 7.28 and in patients with incipient ocular cicatricial pemphigoid, 42.69 degrees +/- 14.33 and 44.46 degrees +/- 16.85. Statistical significance was p < 0.005.

CONCLUSIONS

The lacunar sulci are shallower and vanish sooner in ocular cicatricial pemphigoid and Sjogren syndrome than in normals. Investigating the vanishing point of the lacunar sulci while abducting is useful for grading the shrinkage of the conjunctiva, caruncle and medial canthus.

In vitro activity of CA(1-8)M(1-18), a synthetic cecropin A-melittin hybrid peptide, against multiresistant Acinetobacter baumannii strains

The in vitro antibiotic activity of CA(1-8)M(1-18), a synthetic cecropin A-melittin hybrid peptide, was determined by broth microdilution on 20 clinical Acinetobacter baumannii isolates with different resistance profiles. The MIC(50), MIC(90) and ranges were 4 mg/l, 4 mg/l and 2-8 mg/l, respectively, and were independent of resistance pattern. Different assay parameters such as microplate plastic (polystyrene or polypropylene), addition of supplements (5-10% fetal calf serum or 5% horse blood), inoculum size (10(5), 10(6), 10(7) and 10(8) CFU/ml) or incubation period (24 or 48 h) were studied. MIC was independent of the first two parameters, although the MIC values increased both with inoculum size or incubation period. Killing curves were obtained both for a standard strain and a multiresistant isolate over a 45.7-2.8 mg/l (16-1 mM) peptide range, using an initial inoculum of 10(5)-10(6) CFU/ml and 10(9)-10(10) CFU/ml. A concentration of 45.7 mg/l was required for complete killing. Accordingly, CA(1-8)M(1-18) showed good in vitro activity against the A. baumannii strains tested irrespective of the resistance to classical antibiotics, and could be a future candidate for multiresistant A. baumannii infections, although further cytotoxicity and pharmacological studies will be needed.

Intrinsic structural differences in the N-terminal segment of pulmonary surfactant protein SP-C from different species

Predictive studies suggest that the known sequences of the N-terminal segment of surfactant protein SP-C from animal species have an intrinsic tendency to form beta-turns, but there are important differences on the probable location of these motifs in different SP-C species. Our hypothesis is that intrinsic structural determinants of the sequence of the N-terminal region of SP-C could define conformation, acylation and perhaps surface properties of the mature protein. To test this hypothesis we have synthesized peptides corresponding to the 13-residue N-terminal sequence of porcine and canine SP-C, and studied their structural behaviour in solution and in phospholipid bilayers and monolayers. In these peptides, leucine at position 1 of both sequences has been replaced by tryptophan in order to allow their study by fluorescence spectroscopy. Far-u.v. circular dichroism spectra of the peptides in aqueous and organic solutions and in phospholipid micelles or vesicles are consistent with predicted conformational differences between the porcine and the canine sequences. Both families of peptides showed changes in their fluorescence emission spectra in the presence of phospholipids that were consistent with spontaneous lipid/peptide interactions. Both canine and porcine peptides were able to form monolayers at air-liquid interfaces, the canine peptides occupying lower area/molecule and being compressible to higher pressures than the porcine sequences. The peptides also shifted the isotherms and perturbed the packing of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) monolayers, the effects being always higher in anionic than in zwitterionic lipids, and also substantially higher in films containing canine peptide in comparison to porcine peptide. Acylation of cysteines at the N-terminal end of SP-C may modulate these intrinsic conformational features and the changes induced could be important for the development of its surface activity.

In vivo monitoring of intracellular ATP levels in Leishmania donovani promastigotes as a rapid method to screen drugs targeting bioenergetic metabolism

A method for the rapid screening of drugs targeting the bioenergetic metabolism of Leishmania spp. was developed. The system is based on the monitoring of changes in the intracellular ATP levels of Leishmania donovani promastigotes that occur in vivo, as assessed by the luminescence produced by parasites transfected with a cytoplasmic form of Phothinus pyralis luciferase and incubated with free-membrane permeable D-luciferin analogue D-luciferin-[1-(4,5-dimethoxy-2-nitrophenyl) ethyl ester]. A significant correlation was obtained between the rapid inhibition of luminescence with parasite proliferation and the dissipation of changes in mitochondrial membrane potential (DeltaPsi(m)) produced by buparvaquone or plumbagin, two leishmanicidal inhibitors of oxidative phosphorylation. To further validate this test, a screen of 14 standard leishmanicidal drugs, using a 50 microM cutoff, was carried out. Despite its semiquantitative properties and restriction to the promastigote stage, this test compares favorably with other bioenergetic parameters with respect to time and cell number requirements for the screening of drugs that affect mitochondrial activity.

Interaction of antimalarial drug quinacrine with nucleic acids of variable sequence studied by spectroscopic methods

The interaction of antimalarial drug quinacrine (QA) with polynucleotides is studied by UV-visible absorption, fluorescence and surface-enhanced Raman spectroscopy (SERS). The polynucleotides employed for such a study were calf thymus DNA, poly(A).poly(T), poly(A).poly(U), poly(C).poly(G) and poly(dG-dC).poly(dG-dC). Absorption and fluorescence spectra of QA complexes indicate that an interaction with the biomolecule is taking place, although different interaction mechanisms are probable depending on the sequence. The SERS spectra also reflect spectral changes which depend on the polymer sequence and that can be correlated to those observed by fluorescence, with the advantage of the detailed structural information provided by this vibrational technique. QA interacts with polynucleotides through its diprotonated form and by ring stacking. The strength of such interaction is extremely sequence dependent, thus suggesting different interaction mechanisms in each case. The SERS technique allows the simultaneous study of those polynucleotide moieties that are directly involved in the interaction thanks to the short-range character of the SERS spectroscopy. The interaction of QA with the above nucleic acids lead to a different change in the chain stability and flexibility which is further related to the different denaturation tendency of the polymer in the presence of the metal surface.

Animal antimicrobial peptides: an overview

Antibiotic peptides are a key component of the innate immune systems of most multicellular organisms. Despite broad divergences in sequence and taxonomy, most antibiotic peptides share a common mechanism of action, i.e., membrane permeabilization of the pathogen. This review provides a general introduction to the subject, with emphasis on aspects such as structural types, post-translational modifications, mode of action or mechanisms of resistance. Some of these questions are treated in depth in other reviews in this issue. The review also discusses the role of antimicrobial peptides in nature, including several pathological conditions, as well as recent accounts of their application at the preclinical level.

Spatial and temporal variability of ground-level ozone in Castilla-León (Spain)

Ozone is a secondary air pollutant that has received extensive attention in the literature, mainly because of the adverse effects that exposure to it can cause, particularly in vegetation during the growing season. Because meteorological conditions strongly influence the efficiency of photochemical processes leading to ozone formation and destruction, ground-level ozone air pollution is currently being considered as a regional-scale phenomenon rather than a local one. This role of O3 as a regional-scale pollutant often implies the handling of large data sets in order to obtain information about its spatial and temporal variability patterns over a given broad region. Rotated principal component analysis (RPCA) is known to be one of the most powerful mathematical tools that can be used to achieve this aim. RPCA was applied in this paper to the summer and winter hourly time series of ground-level O3, concentrations recorded during 2 consecutive years (1996-1997) at 26 urban and suburban sites in Castilla-León (Spain). This procedure permitted the identification of different subregions where O3 concentrations show different spatio-temporal variability patterns. These variability patterns are mainly associated with the interaction of regional-level meteorological and anthropogenic factors. Some differences between winter and summer patterns were also found.

Amyloid precursor proteins in the cerebellar cortex of Alzheimer's disease patients devoid of cerebellar beta-amyloid deposits: immunocytochemical study of five cases

Five human brains affected by Alzheimer's disease (AD), but without cerebellar amyloid (A beta) deposits, were investigated for the presence and location of amyloid precursor proteins (APP). This was parallel to 6 AD brains with A beta deposits, 6 young controls and 6 age-matched controls. Antibodies against A beta and two epitopes of APP (amino and carboxy terminals, APP(60-100) and APP(643-695), respectively) were employed. Accumulations of APP in neurons (mainly Purkinje cells) and glial cells in the upper part of the molecular layer were far greater than those in age-matched control brains and similar to those in AD brains with A beta deposits. This suggests that changes in APP production and/or metabolism occur before A beta deposition, or that these changes can occur without amyloidogenic processing. More than 60% of positive Purkinje neurons were of normal appearance; most of them showed both APP(60-100) and APP(643-695) immunoreactivity, but a small number (<21%) reacted with only a single antiserum. A small number of Golgi, Lugaro and granule cells were APP immunopositive. In all cases, stellate and basket cells were negative, as were most glial cells other than those of the molecular layer. Folia showed two different appearances, which were particularly well displayed in three cases: "strongly" immunopositive folia with high reactivity in Purkinje cells and other neurons, and "weakly" immunopositive folia with low neuronal reactivity, but with a large number of positive glial cells in the molecular layer. The results are discussed in relation to the possible existence of types or stages of the AD process and local factors, including specific and non-specific cell factors, in the induction of APP accumulation. All these 5 cases were female, but the Apo-E 4 genotype was displayed only in two cases.