Pulmonary arteriovenous malformation and a concurrent patent ductus arteriosus in a Doberman.

A 7-week-old male Doberman presented with tachypnea, dyspnea and a VI/VI, left cranial, continuous heart murmur. Thoracic radiographs revealed severe left-sided cardiomegaly, presence of a rounded soft tissue opacity in the caudodorsal aspect of the thoracic cavity and signs of left-sided congestive heart failure. Clinical signs of heart failure were medically controlled. Echocardiography and computed tomography demonstrated a left-to-right shunting patent ductus arteriosus (PDA) in combination with a right-to-left shunting pulmonary arteriovenous malformation (PAVM) between the right main pulmonary artery and the right caudal pulmonary vein. Arterial blood gasses revealed mild hypoxemia. Transcatheter occlusion of the PDA using an Amplatz Canine Duct Occluder was performed. Four months post-operatively, echocardiography showed normal cardiac size and function with complete PDA closure. Thoracic radiographs revealed absence of the rounded opacity and resolution of cardiomegaly and vascular congestion. The PAVM was no longer visualized on repeated computed tomography and the arterial blood gasses were within normal limits. A PAVM connecting a pulmonary artery to a pulmonary vein has only rarely been reported in dogs. This report describes the presence of a congenital PAVM in combination with a PDA in a dog, which has not been previously reported in veterinary medicine.

Three-dimensional electroanatomical mapping for guidance of pulmonary vein isolation as treatment for persistent atrial fibrillation in a dog.

A two-year and four-month, male German Shepherd was referred for exercise intolerance and panting. Irregular heart auscultation (250 beats per minute (bpm)) and pulse deficits were noted on physical exam. Electrocardiogram (ECG) showed irregular, narrow-QRS tachycardia without P waves compatible with coarse atrial fibrillation (AF). A 24-h ECG showed sustained AF (mean ventricular response rate 92 bpm). Echocardiography showed no structural abnormalities. Given the young age and presence of AF-related symptoms, rhythm control was preferred. Transthoracic electrical cardioversion was successfully performed six weeks later but AF recurred within 24-h. Sotalol was started but discontinued due to poor tolerance and AF persisted. Seven months after AF diagnosis, radiofrequency catheter ablation (RFCA) aiming for pulmonary vein isolation was performed under general anaesthesia. After transseptal puncture, three-dimensional electroanatomical mapping of the left atrium was performed. Point-by-point pulmonary vein isolation was achieved by RFCA. Seventy-eight RFCA lesions were placed in the left atrium encircling the three pulmonary vein ostia followed by electrical cardioversion. No complications occurred and the dog was discharged with amiodarone. In the immediate post-operative phase, there was recurrence of persistent AF requiring electrical cardioversion. Furthermore, at one month after the ablation, the dog experienced a single and transient paroxysm of AF. Since then, stable sinus rhythm (SR) was retained on daily ECG monitoring at home and confirmed by 24-h ECG three months post-operatively. Amiodarone was stopped subsequently. At the time of writing (one year post-operative), the dog remains in SR with normal exercise tolerance.

Feasibility and safety of three-dimensional electroanatomical cardiac mapping, mapping-guided biopsy and transseptal puncture in dogs.

Three-dimensional electroanatomical mapping (3D EAM) has expanded radiofrequency catheter ablation applications in humans to almost all complex arrhythmias and has drastically reduced fluoroscopy use, yet its potential in dogs is poorly investigated. The objectives of the current study were to assess the feasibility and safety of 3D EAM of all four heart chambers, 3D EAM-guided biopsies and transseptal puncture in dogs. Eight healthy purpose-bred Beagle dogs. Electroanatomical mapping was performed under general anaesthesia during sinus rhythm using a 22-electrode mapping catheter. Left heart catheterisation was achieved by either retrograde transaortic access (n = 4) or transseptal puncture (n = 4). Successful 3D EAM of the right atrium and ventricle was achieved in all dogs at a median time of 33 (13-40) min and 17 (3-52) min, respectively. Left atrial and ventricular 3D EAM was successful in six and seven dogs, at a median time of 17 (4-27) min and 8 min (4-19 min), respectively. Complications requiring intervention occurred in one dog only and were a transient third degree atrioventricular block and pericardial effusion following transseptal puncture, which was treated by pericardiocentesis. All dogs recovered uneventfully. Fluoroscopy time was limited to a median of 7 min (0-45 min) and almost exclusively associated with transseptal puncture. Three-dimensional EAM of all cardiac chambers, including mapping-guided biopsy and transseptal puncture is feasible in small dogs. Complications are similar to those reported in human patients. This suggests a potential added value of 3D EAM to conventional electrophysiology in dogs with arrhythmias.

Serum hyaluronic acid, a marker for improved liver perfusion after gradual surgical attenuation of extrahepatic portosystemic shunt closure in dogs.

Current liver function tests used in dogs do not consistently normalise after successful surgical attenuation of portosystemic shunts (PSS). Serum hyaluronic acid (sHA) concentrations in dogs with PSS are reported to be higher at diagnosis than in healthy dogs. The objective of this study was to assess sHA as a marker of liver perfusion by measuring sHA concentrations in dogs before and after gradual surgical attenuation of extrahepatic (EH)PSS and by determining whether sHA concentrations could differentiate closed EHPSS from persistent shunting. Specificity of sHA was assessed by comparing sHA concentrations in dogs with EHPSS to those in dogs with other liver diseases. Twenty dogs with EHPSS had sHA concentrations measured at diagnosis, 1, 3, and 6 months postoperatively. In addition, sHA concentrations were determined in 10 dogs with other liver diseases. At EHPSS diagnosis, median sHA concentration was 335.6 ng/mL (43.0-790.7 ng/mL). All dogs had a significant decrease in sHA concentrations from 1 month postoperatively onwards (P < 0.05), regardless of surgical outcome. At all postoperative follow-up visits, there was a significant difference between the median sHA concentration in dogs with closed EHPSS vs. those with persistent shunting (P < 0.05). Median sHA concentration in dogs with other liver diseases was 89.8 ng/mL (22.9-160.0 ng/mL), which was significantly lower than dogs with EHPSS at diagnosis (P < 0.001). In conclusion, sHA is a promising non-invasive biomarker that can help to determine liver perfusion after surgical attenuation of EHPSS. In addition, sHA could potentially be used to differentiate dogs with EHPSS from dogs with other liver diseases.

Optical imaging of electrical carrier injection into individual InAs quantum dots.

We image the micro-electroluminescence (EL) spectra of self-assembled InAs quantum dots (QDs) embedded in the intrinsic region of a GaAs p-i-n diode and demonstrate optical detection of carrier injection into a single QD. Tunneling of electrons and holes into the QDs at bias voltages below the flat-band condition leads to a spectrum of sharp EL lines from a small number of bright spots on the diode surface, characteristic of emission from individual QDs. We explain this behavior in terms of Coulomb interaction effects and the selective excitation of a small number of QDs within the ensemble due to preferential tunneling paths for carriers.

Contrast-Enhanced Ultrasound Examination for the Assessment of Renal Perfusion in Cats with Chronic Kidney Disease.

BACKGROUND: Contrast-enhanced ultrasound examination (CEUS) is a functional imaging technique allowing noninvasive assessment of tissue perfusion. Studies in humans show that the technique holds great potential to be used in the diagnosis of chronic kidney disease (CKD). However, data in veterinary medicine are currently lacking. OBJECTIVES: To evaluate renal perfusion using CEUS in cats with CKD. ANIMALS: Fourteen client-owned cats with CKD and 43 healthy control cats. METHODS: Prospective case-controlled clinical trial using CEUS to evaluate renal perfusion in cats with CKD compared to healthy control cats. Time-intensity curves were created, and perfusion parameters were calculated using off-line software. A linear mixed model was used to examine differences between perfusion parameters of cats with CKD and healthy cats. RESULTS: In cats with CKD, longer time to peak and shorter mean transit times were observed for the renal cortex. In contrast, a shorter time to peak and rise time were seen for the renal medulla. The findings for the renal cortex indicate decreased blood velocity and shorter total duration of enhancement, likely caused by increased vascular resistance in CKD. Increased blood velocity in the renal medulla has not been described before and may be because of a different response to regulatory factors in cortex and medulla. CONCLUSIONS AND CLINICAL IMPORTANCE: Contrast-enhanced ultrasound examination was capable of detecting perfusion changes in cats with CKD. Further research is warranted to assess the diagnostic capabilities of CEUS in early stage of the disease process.

Variability of serum concentrations of cystatin C and urinary retinol-binding protein, neutrophil gelatinase-associated lipocalin, immunoglobulin G, and C-reactive protein in dogs.

BACKGROUND: Markers of kidney dysfunction and damage have potential to detect chronic kidney disease (CKD) in early stages. However, data on long-term variation of these markers in healthy dogs is lacking and is crucial for the interpretation of results. HYPOTHESIS/OBJECTIVES: To determine temporal variations of serum cystatin C (sCysC) and urinary retinol-binding protein (uRBP), neutrophil gelatinase-associated lipocalin (uNGAL), immunoglobulin G (uIgG), and C-reactive protein (uCRP) in healthy dogs. ANIMALS: Eight clinically healthy adult Beagles were evaluated. METHODS: Longitudinal observational study. Serum cystatin C was determined by particle-enhanced nephelometric immunoassay. Urinary retinol-binding protein, uNGAL, uIgG and uCRP were determined by ELISA and concentrations were indexed to urinary creatinine. Within- and between-dog variance components (VC) and within-dog coefficients of variation (CV) were determined from blood and urine collected at eight time points over 1.5 years. RESULTS: Urinary C-reactive protein (uCRP) concentrations were consistently below the detection limit (5.28 ng/mL). Mean ± within-dog standard deviation for sCysC, uRBP/c, uNGAL/c and uIgG/c was 0.15 ± 0.01 mg/L, 0.09 ± 0.03 mg/g, 2.32 ± 2.03 µg/g and 12.47 ± 10.98 mg/g, respectively. Within-dog CV for sCysC, uRBP/c, uNGAL/c and uIgG/c was 8.1%, 33.7%, 87.2% and 88.1%, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Serum cystatin C, uRBP/c, uNGAL/c and uIgG/c exhibit a wide range of long-term within-dog variability. Researchers and veterinarians might need to take this into account when interpreting their results. To assess their diagnostic and predictive ability, future studies need to establish reference ranges for healthy dogs and dogs with CKD.

A single dose of intravenous combretastatin A4-phosphate is reasonably well tolerated and significantly reduces tumour vascularization in canine spontaneous cancers.

Combretastatin A4-phosphate (CA4P) is an anti-tumour vascular targeting agent which selectively blocks tumour blood flow. Research on CA4P in rodent tumour models is extensive; however, knowledge of its effect on spontaneous cancer is scarce. This study was conducted in canine patients with spontaneous solid tumours. The goal was to assess the toxicity and efficacy of CA4P in various spontaneous tumour types. Eight dogs with spontaneous tumours were enrolled and treated with a single dose of 75 mg m-2 intravenous CA4P. The dogs were screened and monitored before and after injection. Pre- and post-treatment tumour blood flow was analysed in vivo by power Doppler ultrasound (PDUS) and contrast-enhanced ultrasound (CEUS). Vessel destruction and tumour necrosis were evaluated by histopathology. Clinically relevant toxicity was limited to one case of temporary tetraparesis; other adverse events were mild. Significant cardiovascular changes were mostly confined to changes in heart rate and cTnI levels. Macroscopic tumour size reduction was evident in 2 dogs. Based on PDUS and CEUS, CA4P induced a significant decrease in vascular index and tumour blood flow. Post-treatment, histopathology revealed a significant increase of necrotic tumoural tissue and a significant reduction in microvessel density in tumoural tissue. Anti-vascular and necrotizing effects of CA4P were documented in a variety of canine spontaneous cancers with only minimal side effects. This is the first study reporting the administration of CA4P to canine cancer patients with in vivo and ex vivo assessment, and a first step toward implementing CA4P in combination therapies in veterinary oncology patients. The use of CA4P in canine patients was approved and registered by the Belgian Federal Agency for Medicines and Health Products (FAMHP) (approval number 0002588, registration number 6518 ID 2F12).

Non-classical light emission from a single electrically driven quantum dot.

Easy to handle light sources with non-classical emission features are strongly demanded in the growing field of quantum communication. We report on single-photon emission from an electrically pumped quantum dot with unmatched spectral purity, making spatial or spectral filtering dispensable.

Evaluation of Renal Perfusion in Hyperthyroid Cats before and after Radioiodine Treatment.

BACKGROUND: Hyperthyroidism and chronic kidney disease (CKD) are common in elderly cats. Consequently, both diseases often occur concurrently. Furthermore, renal function is affected by thyroid status. Because changes in renal perfusion play an important role in functional renal changes in hyperthyroid cats, investigation of renal perfusion may provide novel insights. OBJECTIVES: To evaluate renal perfusion in hyperthyroid cats with contrast-enhanced ultrasound (CEUS). ANIMALS: A total of 42 hyperthyroid cats was included and evaluated before and 1 month after radioiodine treatment. METHODS: Prospective intrasubject clinical trial of contrast-enhanced ultrasound using a commercial contrast agent (SonoVue) to evaluate renal perfusion. Time-intensity curves were created, and perfusion parameters were calculated by off-line software. A linear mixed model was used to examine differences between pre- and post-treatment perfusion parameters. RESULTS: An increase in several time-related perfusion parameters was observed after radioiodine treatment, indicating a decreased blood velocity upon resolution of the hyperthyroid state. Furthermore, a small post-treatment decrease in peak enhancement was present in the renal medulla, suggesting a lower medullary blood volume. CONCLUSIONS AND CLINICAL IMPORTANCE: Contrast-enhanced ultrasound indicated a higher cortical and medullary blood velocity and higher medullary blood volume in hyperthyroid cats before radioactive treatment in comparison with 1-month post-treatment control.

Intratumoural interleukin 12 gene therapy stimulates the immune system and decreases angiogenesis in dogs with spontaneous cancer.

Interleukin 12 (IL-12) is a powerful immunostimulatory cytokine with a strong antitumoural activity. In this work, the immunological, anti-angiogenic and clinical effects of three consecutive intratumoural IL-12 electrogene therapy (EGT) treatments were evaluated in nine dogs with spontaneous cancer. In all the dogs, tumour biopsies and blood samples were taken prior, during and after the intratumoural IL-12 EGT (on days 1, 8, 35 and 1, 3, 8, 15, 35, respectively). An initial decrease in immune cells was followed by an increase above baseline 1-3 weeks after treatment initiation. Interestingly, the decrease in peripheral leukocytes 2 days after the first intratumoural IL-12 EGT coincided with erythema and tumour swelling. Transient increases of IL-12 and interferon γ were measured in the serum and the tumour tissue, whereas IL-10 transiently increased only in the serum. The effect of intratumoural IL-12 EGT on the levels of IL-24 and vascular endothelial growth factor in the sera and tumour biopsies differed per dog. Via contrast-enhanced ultrasound (US) (on days 1, 8 and 35), we demonstrated that intratumoural IL-12 EGT resulted in a significant decrease of the relative blood volume and blood flow speed in the tumour compared with baseline. Metastases were present in two dogs. In one of these dogs, IL-12 EGT of the primary tumour caused a transient partial regression of the metastases, but not of the primary tumour. The second dog with metastases did not survive long enough to complete the entire treatment cycle. Despite encouraging immunostimulatory and anti-angiogenic effects after intratumoural IL-12 EGT, no clinically relevant outcomes were observed in this study, as persistent tumour regression could not be obtained. On the other hand, the laboratory and US results hold great promise for combinatorial strategies of intratumoural IL-12 EGT with conventional antitumour (immuno)therapies.

Adhesion complex formation after small keratectomy wounds in the cornea.

The adhesion complex of the corneal epithelium consists of the hemidesmosome and its associated structures, such as anchoring filaments, lamina densa of the basement membrane, and anchoring fibrils. It contributes to the adhesion of the corneal epithelium to Bowman's layer. To understand the adhesion complex better, an electron microscopic and immunofluorescence analysis was done of the reformation of the adhesion complex in small (1 mm) keratectomy wounds in the guinea pig cornea. In these wounds, the epithelium, hemidesmosomes, basal lamina, anchoring fibrils, and anterior stroma were removed. The wound bed was epithelialized completely by 24 hr after wounding. Immunofluorescence analyses involved the use of antibodies against plaque components of the hemidesmosome, an antibody against laminin, and an antibody against the collagen VII component of anchoring fibrils. At 18 hr after wounding, there was no morphologic evidence of hemidesmosomes at the epithelial-stromal interface. At 24 hr, hemidesmosomes were observed, with or without subjacent lamina densa. Furthermore, plaque components were detected by immunofluorescence in those cells in contact with the wound bed. In contrast, no type VII collagen was detected. On day 7, collagen VII, laminin, and bullous pemphigoid autoantibody markers colocalized along the wound bed as determined by immunofluorescence. However, at the ultrastructural level, even though the lamina densa of the basal lamina was observed primarily where hemidesmosomes were present, it remained incomplete. In this study, the precise temporal sequence in which components are incorporated into the assembling adhesion complex was described during wound healing. Furthermore, the possibility that the hemidesmosomal plaque nucleates the formation of the underlying basal lamina was discussed.

Expression of the 55-kD/64-kD corneal keratins in ocular surface epithelium.

According to the concept of keratin pairing defined by tissue coexpression, a 55-kD/64-kD keratin pair is a marker of "corneal-type" differentiation. Intermediate filament (IF)-enriched preparations from guinea pig and bovine corneal epithelium were analyzed, and a rabbit antiserum was generated against a 55-kD polypeptide enriched in these preparations. This antiserum generated a typical IF-like pattern in cultured bovine corneal epithelial cells. Immunofluorescence microscopic analysis of frozen sections of guinea pig and bovine tissue revealed that the 55-kD antiserum labeled corneal and limbal epithelium. In addition, the antiserum stained a subpopulation of peripheral limbal cells that were distributed in both basal and suprabasal layers of the epithelium. The monoclonal antibody AE5 was used to investigate the distribution of the 64-kD polypeptide in guinea pig and bovine tissue. Immunoblotting analysis revealed that AE5 antibodies recognized a 64-kD polypeptide in guinea pig cornea, but recognized a 66-kD polypeptide in bovine cornea. Immunofluorescence microscopic analysis of guinea pig tissue revealed that AE5 antibodies labeled suprabasal layers of corneal epithelium, in suprabasal layers of limbal epithelium, and in groups of cells in the peripheral limbal epithelium. We discuss the possibility that the ocular epithelial cells recognized by either the 55-kD or the 64-kD antibodies in the peripheral limbus may play a role in the reepithelialization of the cornea after wounding.

Pathogenesis of experimental lipid keratopathy: corneal and plasma lipids.

Corneal and plasma lipids were studied in a rabbit model to gain insight into the pathogenesis of secondary lipid keratopathy. Rabbits were divided into four groups in which a high cholesterol diet and corneal suture placement were varied to produce lipid keratopathy. In rabbits with lipid keratopathy, quantitative thin layer chromatography revealed that cholesterol esters comprised most of the deposited lipid, with free cholesterol being deposited as well. The ratio of accumulated cholesterol ester to free cholesterol corresponded closely to the same ratio in hypercholesterolemic plasma total low and very low density lipoprotein (TLDL). Furthermore, gas chromatography showed that the cholesterol ester composition in the corneas with lipid keratopathy resembled that seen in hypercholesterolemic plasma TLDL but was different from the pattern observed in the normal cornea. These studies suggest that the direct source of the deposited cholesterol ester is primarily the plasma TLDL. Since phospholipids and triglycerides did not show a significant increase in the experimental corneas, they are presumably metabolized by the keratocytes after the uptake of TLDL. However, the amount of cholesterol ester carried by the lipoprotein exceeds the capacity of the cell for use and excretion and the lipid accumulates in the cornea.

The effect of platelet-activating factor (PAF), histamine, and ethanol on vascular permeability of the guinea pig conjunctiva.

Increased vascular permeability, one of the characteristic features of immediate hypersensitivity (Type I), is mediated through a variety of compounds, including histamine and platelet-activating factor (PAF), a phospholipid inflammatory mediator. The effects on vascular permeability of histamine, PAF, and ethanol, the solvent for PAF, were compared in the guinea pig conjunctiva. Permeability at 30 min was investigated by evaluation of conjunctival edema and Evans blue extravasation (clinically estimated and colorimetrically measured). Doses of PAF from 1 to 10 nmol produced an increase in vascular permeability, with a peak effect at 10 nmol. Ethanol had no effect on vascular permeability below 40 X 10(3) nmol; above this concentration, however, permeability increased, reaching a maximum at 175 X 10(3) nmol. At low doses of PAF and ethanol, the effects were additive, whereas at 20-80 nmol of PAF with high concentrations of ethanol there was no additive effect of PAF, producing a decrease in the net effect of PAF. Histamine increased vascular permeability, with a minimum effect at 10 nmol and a maximum effect at 450 nmol. The slopes of the dose-response curves for all three compounds were linear and parallel, with statistically different potencies. The potencies for each compound were identical by all three methods of evaluation. Therefore, we conclude that PAF is a potential mediator in hypersensitivity reaction in the guinea pig conjunctiva, and that its effect is similar to but much more potent than that of histamine or ethanol. Since ethanol alone has a significant effect on vascular permeability, studies on PAF effects using control solutions without ethanol may be difficult to interpret.

Pathogenesis of experimental lipid keratopathy. An ultrastructural study of an animal model system.

The histology and ultrastructure of experimental lipid keratopathy were studied in hypercholesterolemic rabbits in which the insertion of corneal sutures induced vascularization and subsequent lipid deposition in the anterior stroma. Lipid accumulated in the keratocytes, the pericytes and occasionally in the endothelial cells of the capillaries. The lipid-laden keratocytes were concentrated in the region of the capillaries. No lipid was seen in the control rabbits. In the hypercholesterolemic rabbit with sutures, intracellular lipid in the keratocytes was present largely in nonmembrane-limited droplets with smaller amounts of membrane-limited cholesterol crystals and rare numbers of myelin figures. In addition, large, lipid-engorged spherical cells were present. The numerous phagolysosomes seen ultrastructurally suggest that some of these cells probably represent macrophages. Keratocytes and the large, spherical lipid-engorged cells show focal degenerative changes, including pyknotic nuclei, cytoplasmic coagulation and membrane loss, leaving extracellular mixed accumulations of lipid and cytoplasmic organelles. Small numbers of lymphocytes and plasmacytoid cells were present. No corneal lipid was seen in animals with normocholesterolemia, with or without sutures. In hypercholesterolemic animals, a few lipid-laden keratocytes without macrophages were identified even in the absence of vessels. These morphologic studies support the hypothesis that the accumulation of the corneal lipid in this animal model of lipid keratopathy is the result of increased lysosomal uptake of lipid, probably as low density lipoprotein, from the extracellular space by the keratocytes. The rate of metabolism of this lipid is insufficient to clear the cells of the lipid and the subsequent lipid inspissation results in keratocyte death, leading to macrophage accumulation of lipid and free lipid in the stroma.

Endothelial viral inclusions in Fuchs' corneal dystrophy.

A case of Fuchs' corneal dystrophy is presented. The patient, a 70-year-old white woman, had bilateral decreasing vision, especially while reading and driving at night. Clinical features were characteristic of Fuchs' corneal dystrophy. Ultrastructural studies demonstrated findings in Descemet's membrane typical of those previously reported with numerous tactoids of fibrous long-spacing collagen in the posterior collagenous layer and in the guttata. In the endothelial cells were encapsulated ellipsoid viral particles, 400 nm long and 225 nm in diameter. They contained an outer and inner membrane with an electron-dense intervening region and a central dense core. Nucleocapsids were present in the endothelial cells and stromal keratocytes. The authors suggest that the pathogenesis of Fuchs' corneal dystrophy may be endothelial damage, and that in this case, the etiology is a viral infection.

Experimental Bacteroides fragilis keratitis.

To determine the corneal pathogenicity of certain anaerobic bacteria, Bacteroides fragilis keratitis was induced in rabbits by the intrastromal inoculation of 10' viable organisms. All eyes inoculated developed central abscesses within 24 hours. Abscesses persisted and became vascularized in two of three eyes that were observed for two weeks, as demonstrated both clinically and histologically. Eyes inoculated superficially with live organisms or intrastromally with solutions of dead organisms did not develop inflammatory lesions. Anaerobically incubated blood agar plates and thioglycollate broth were equally efficient in recovering organisms, although longer incubation times were occasionally necessary to recover organisms from broth cultures. Bacteroides fragilis and other anaerobic bacteria should be considered in the differential diagnosis of bacterial keratitis, and specific methods should be used to recover these organisms.

Desquamating endotheliopathy. An incipient iridocorneal endothelial syndrome?

Unilateral, noninfectious, nontraumatic corneal endotheliopathy was noted in a 34-year-old man who had had blurred vision for five years without evidence of iridic disease or glaucoma. Ultrastructural studies demonstrated focal necrosis of the corneal endothelial cells, with desquamation of the cells into the anterior chamber. The corneal endothelium appeared to expand beneath the dying endothelial cells, indicating reendothelialization of the cornea. There was no epithelialization of the endothelium, as evidenced by the lack of keratin production or desmosome formation. Descemet's membrane was thickened with edema, a posterior collagenous layer, and fibrous, long-spacing collagen. These alterations in Descemet's membrane were similar to those described for other corneal dystrophies. It is proposed that this unilateral desquamating endotheliopathy represents an incipient form or a forme fruste of the iridocorneal endothelial syndrome.

Clostridium perfringens corneal ulcer.

A corneal ulcer caused by Clostridium perfringens developed in a 76-year-old woman with Sjögren's syndrome. Experimental C perfringens keratitis was induced in rabbits by the intrastromal injection of 10(7) organisms. In both our patient and the experimental animals, a bullous lesion overlay the affected area of the cornea. This may be a specific lesion in clostridial infections of the cornea. Clostridium perfringens should be regarded as an opportunistic corneal pathogen, and anaerobic cultures should be performed in all cases of suspected bacterial corneal ulcer.