BIGH3 gene mutations and rapid detection in Korean patients with corneal dystrophy

PURPOSE

Mutations in the BIGH3 gene on chromosome 5q31 cause four distinct autosomal dominant corneal dystrophies. We sought to determine whether the BIGH3 gene mutation was responsible for corneal dystrophy in Korean patients.

METHODS

Polymerase chain reaction single strand conformational polymorphism (PCR-SSCP) analysis was performed with the DNA from patients and healthy individuals. We sequenced the PCR products with the aberrant SSCP pattern to identify the mutation. Mutant-specific reverse primers were used to screen genomic DNA for the identified mutations.

RESULTS

We identified mutations R124C in the CDL1 family and R124H in four families with a granular dystrophy. We identified our granular dystrophy to be Avellino corneal dystrophy (ACD). Eighteen of 20 patients with a granular dystrophy contained the same R124H mutation, indicating that mutation R124H was very common in Korean patients with ACD. During this study, we identified a new polymorphism (T1667C, F540F).

CONCLUSIONS

This is the first report of mutations found in the BIGH3 gene in Korean families with corneal dystrophy. We report that the majority (90%) of ACD patients in Korea carry the R124H mutation. Mutant-specific reverse primers can be used to screen efficiently for CDL1 and ACD.

Conjunctival epithelial cells cultured on human amniotic membrane fail to transdifferentiate into corneal epithelial-type cells

PURPOSE

Previous studies on the use of human amniotic membrane (HAM) in rabbit stem cell deficiency models have found the new epithelium growing over the HAM to express cornea-specific keratins (K3 and K12) in 40% of the cases, suggesting that HAM may have induced conjunctival epithelial cells to transdifferentiate into cornea-type epithelial cells. The current study was performed to determine whether HAM could induce transdifferentiation of conjunctival epithelia] cells when cultured in vitro.

METHODS

Conjunctival grafts taken from the fornices of New Zealand white rabbits (6-12 weeks old) were placed over HAMs and lifted to an air-media interface using polypropylene double rings. These cultures were maintained in supplemented hormonal epithelial medium with and without 3T3 feeder cells. Rabbit corneal epithelial cells were cultured similarly using strips of keratolimbal grafts placed over HAM. The cultures were terminated at various times between the 8th and 15th day. The cultured epithelial cells were examined histologically and immunohistochemically using monoclonal antibodies AK-2 (to K12 keratin), AM-3 (to goblet cell mucin), and AE-5 (to K3 keratin).

RESULTS

Both conjunctival and corneal epithelial cells cultured on HAMs showed multilayered, differentiated epithelial structures. On immunohistochemical examination, both epithelial cells stained positive for AE-5. None of the cultured conjunctival epithelial cells stained positively for AK-2, while the corneal epithelial cells showed positive staining with AK-2. There were no AM-3-positive goblet cells in either epithelial cell culture. There was no difference in the immunohistochemical patterns between cultures with or without 3T3 feeder cells. However, culture without feeder cells seemed to manifest a more degenerative appearance than those with feeders.

CONCLUSION

HAM does not induce transdifferentiation of conjunctival epithelial cells into corneal-type epithelial cells under the in vitro culture conditions used in this study.

Ex vivo transduction of corneal epithelial progenitor cells using a retroviral vector

PURPOSE

To transduce corneal epithelial progenitor cells with a reporter gene using a retroviral vector and follow their progeny in vitro and in vivo.

METHODS

Using a lacZ-producing retroviral vector, rabbit keratolimbal explants were transduced ex vivo, autografted onto their original sites, and assessed for lacZ-producing cells in the cornea throughout a 6-month period. Four autografts served as control samples, having received no vector. Experimental and control rabbits were euthanized and corneas with scleral rims harvested, weekly for 4 weeks and then monthly for 6 months. The corneas were first stained with 5-bromo-4-chloro-3-indolyl galactopyranoside (X-gal) as wholemounts and then sectioned for histology and immunohistochemistry to examine lacZ-positive cell outgrowth. Three additional transduced explants were observed in culture. These explants were transferred to new culture dishes every week for 9 weeks. The previously occupied culture dish was stained for lacZ to detect transduced epithelial cells, and the number of lacZ-positive cells was quantitated.

RESULTS

LacZ-positive cells were found in the corneas of 18 of 20 eyes in which virally transduced keratolimbal autografts had been implanted. The cells were epithelial in nature, originated from the limbus, and were found in colonies throughout the epithelial layer of the cornea. The appearance of lacZ-positive cells in four of five corneas harvested after 6 months showed long-term transgene expression consistent with transduction of corneal epithelial stem cells. In vitro, the number of lacZ-positive cells migrating from the keratolimbal autografts decreased rapidly during the first 4 weeks and then remained stable through week 9.

CONCLUSIONS

This study shows that a retroviral vector can effectively transduce corneal epithelial progenitor cells, shown by the long-term appearance of transduced cells on the cornea in vivo and the stable production of lacZ-positive cells in vitro. The appearance and disappearance of labeled cells is consistent with the initial transduction of stem cells and transient amplifying cells.

In vivo tandem scanning confocal microscopy in acanthamoeba keratitis

The in vivo confocal microscopy technique provides us with a real-time, non-invasive way of examining the human cornea. The most important advantage of this type of microscopy is to reveal the etiologic agents in infectious keratitis such as Acanthamoeba keratitis. We present several representative cases of Acanthamoeba keratitis, which were diagnosed in their early stages using in vivo confocal microscopy and managed based on that diagnosis. In our Acanthamoeba keratitis cases, highly-reflective round or ovoid organisms with a diameter of about 10-25 um were visualized distinctly against relatively-dark normal parenchymal structures, such as epithelial cells or keratocyte nuclei. Double-walled structures of Acanthamoeba cysts were clearly demonstrated in some cases. We can confirm that in vivo tandem scanning confocal microscopy is a powerful diagnostic tool for identifying the infecting organisms in Acanthamoeba keratitis.

In vivo confocal microscopic analysis of corneal allograft rejection in rabbits

PURPOSE

To demonstrate in vivo confocal microscopic features of corneal allograft rejection that may be useful for differentiating graft rejection from other conditions.

METHODS

Corneal donor buttons from Dutch Belted (DB) pigmented rabbits were transplanted orthotopically into New Zealand White (NZW) recipient corneal beds. Slit-lamp and confocal microscopic examinations were performed every 3 days thereafter until the time of graft failure.

RESULTS

Allograft-rejection signs began to appear during the fourth postoperative week. In epithelial rejection, small inflammatory cells were visualized forming a linear rejection line mixed with larger damaged epithelial cells. Subepithelial infiltrates (SEIs) could be discerned as aggregates of small and highly refractile inflammatory cells within the extracellular matrix. An area of stromal rejection showed increased reflectivity of stromal edema with numerous small infiltrated inflammatory cells. Keratic precipitate (KP) was visualized to be protruding into the anterior chamber with surrounding normal polygonal endothelial cells at its base. Endothelial rejection lines were formed by cellular aggregates of small inflammatory cells and damaged larger endothelial cells with pyknotic highly reflective nuclei. With the progression of endothelial rejection, damaged endothelial cells decreased in number, increased in size, and extended pseudopod-like cytoplasmic structures.

CONCLUSION

In vivo confocal microscopy can provide us with detailed histopathology of corneal graft rejection, which might be useful for differentiating immune rejection from other graft conditions and may provide a technique for early diagnosis of rejection before slit-lamp findings.

The infusion rate of mivacurium and its spontaneous neuromuscular recovery in magnesium-treated parturients

Magnesium (Mg) enhances the activity of nondepolarizing neuromuscular blocking drugs. However, no interaction between mivacurium and magnesium has been described. Therefore, we sought to determine the effect of the influence of Mg on the infusion rate of mivacurium and its spontaneous recovery. We studied 24 parturients who had undergone cesarean section under general anesthesia. Those who had been given MgSO4 for the treatment of preeclampsia were assigned to the Mg group (n = 12), and the other normal parturients were assigned to the NonMg group (n = 12). In both groups, the train-of-four (TOF) response to stimuli of the ulnar nerve was measured at intervals of 15 s. Anesthesia was induced with thiopental and succinylcholine. In both groups, a bolus dose of mivacurium 0.06 mg/kg was administered when the first twitch of TOF (T1) reached 100% after the succinylcholine injection. When the electromyographic response after mivacurium had recovered to approximately 5%-10% of the baseline, a continuous infusion of mivacurium was given to maintain 93%-97% neuromuscular blockade. The plasma concentration of Mg in blood of the Mg group was 4.0 1.0 mEq/L, higher than that (1.4 mEq/L) of the NonMg group (P < 0.01). The infusion rates of mivacurium of Mg and NonMg groups were 1.6 and 5.4 mEq x kg(-1) x min(-1), respectively. In addition, the recovery indexes of the Mg and NonMg groups were 12.9 and 4.3 min, respectively. We conclude that a smaller dose of mivacurium should be infused to patients receiving Mg.

IMPLICATIONS

Magnesium, used as a standard therapy for severe toxemia, may act to enhance muscle relaxants such as mivacurium, a short-acting drug used in general anesthesia. Among women undergoing a cesarean section who were given a magnesium pretreatment, the infusion rate of mivacurium required to obtain relaxation was lower than that among women who did not receive pretreatment.

Tandem scanning confocal microscopic analysis of differences between epithelial healing in limbal stem cell deficiency and normal corneal reepithelialization in rabbits

PURPOSE

To analyze the differences in epithelial healing between limbal stem cell-deficient corneas and normal corneas by using in vivo confocal microscopy.

METHODS

Two different injury models were made in rabbit eyes by using n-heptanol to create a corneal epithelial defect with (limbal stem cell-deficiency model) or without (normal corneal reepithelialization model) peripheral limbal keratectomy. Using a tandem scanning confocal microscope (TSCM), we examined and compared the epithelial healing processes of the two different injury models. Impression cytology and pathologic examination were done on limbal stem cell-deficient corneas.

RESULTS

In limbal stem cell-deficient corneas, the healing epithelial cells were smaller and more variable in size compared with those in normal corneas. In limbal stem cell-deficient corneas, the epithelial thickness varied from one to six cell layers, with the middle and basal cell layer cells being lined up in a certain direction in some areas. The basement membrane was uneven and partially deficient; in some areas, the deep basal epithelial cells were mixed with fibrous strands extending from the anterior stroma. New vessels were located in various levels, from epithelium to deep stroma. These findings were not seen in the normal corneal reepithelialization. In both epithelial-healing models, particularly in the normal corneal reepithelialization, the superficial squamous cells in the early healing stage were considerably larger than those in nontraumatized normal corneas.

CONCLUSION

TSCM is a useful technique for studying the in vivo microscopic structure of many corneal diseases and injury models sequentially over time.

Differentiation of residual or recurrent tumors from post-treatment changes with F-18 FDG PET

Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) was used to differentiate recurrent or residual malignant disease from the effects of cancer treatment. Transaxial images were obtained after injection of 5-10 mCi (185-370 MBq) of F-18 FDG in 68 patients (including 33 with brain tumors) whose posttreatment computed tomographic (CT) or magnetic resonance (MR) imaging findings had been suggestive of malignant disease. PET findings were correlated with surgical results in 18 patients and with the outcomes of CT, MR imaging, clinical, and laboratory 9-month follow-up studies in 50 patients. There was good agreement between F-18 FDG uptake and presence or absence of malignant disease except in four cases of brain tumors in which histologic findings could not be correlated with biologic behavior. The putative sensitivity and specificity in the 33 cases of brain tumors were 80% and 94%, respectively. The authors conclude that PET with F-18 FDG is useful in detection of previously treated metabolically active tumors but is limited in diagnosis of recurrent microscopic or metabolically inactive tumors.

Requirements for in vitro growth of human thymocytes

Since it is difficult to study human thymocyte maturation in vitro, we have developed an in vitro thymocyte culture system which has allowed us to select the optimal growth conditions for thymocyte subpopulations. Three thymocyte subpopulations (CD3-CD1-, CD1+CD3-, and CD3+CD1-) were isolated by a single step percoll density gradient centrifugation and indirect panning procedure using anti-CD1 and anti-CD3 monoclonal antibodies, and their purity was checked by flow cytometry. The combination of concanavalin A (Con A), tetradecanoylphorbol acetate (TPA), and IL-2 was shown to be the most reliable stimulus for the proliferation of CD3-CD1- thymocytes for up to 15 days in a culture system in vitro. Flow cytometric analysis for the phenotypic change of CD3-CD1- thymocytes revealed a steady increase of CD3 antigen after a 3-day cultivation, whereas there was no change in CD1 antigen intensity. A combination of Con A and IL-2 was both sufficient and necessary to induce growth of CD3+CD1- thymocytes. The major population of immature cortical thymocytes (CD3-CD1+ or CD3+CD1+), which are considered to be the most unresponsive dead-end cells, could not be maintained or stimulated with any combination used in this experiment, even in the presence of thymic accessory cells.

Cryotherapy for retinopathy of incontinentia pigmenti

A case with typical skin lesions of incontinentia pigmeti showed progressing retinal vascular abnormalities. So cryotherapy was done on avascular peripheral retina, and retinal vascular changes ceased. We propose that cryotherapy may be a good treatment method for progressing retinal vascular lesions of incontinentia pigmenti.