Trypanothione as a target in the design of antitrypanosomal and antileishmanial agents

Trypanothione is the key molecule in the defence mechanism of Trypanosoma and Leishmania against oxidative stress. The uniqueness of trypanothione makes the metabolism of this molecule an attractive target in antitrypanosomal and antileishmanial drug design. It became clear that this antioxidant cascade can be considered as the "Achilles heel" of these parasites. The following targets and their respective inhibitors will be discussed: biosynthesis of trypanothione with glutathionylspermidine synthetase and trypanothione synthetase; biosynthesis of glutathione with gamma-glutamylcysteine synthetase; biosynthesis of spermidine with ornithine decarboxylase; trypanothione hydroperoxide metabolism with tryparedoxine peroxidase, tryparedoxine and trypanothione reductase.

Abnormal collagen fibrils in nanophthalmos: a clinical and histologic study

PURPOSE

To report the successful treatment of choroidal detachment in a patient with nanophthalmos and to report histopathologic findings in this patient's sclera.

METHODS

Choroidal detachment, secondary angle closure, and nanophthalmos were diagnosed using biomicroscopy, indirect ophthalmoscopy, and echography. Full-thickness sclerectomies in four quadrants were made on the right eye. Sclerae from these sclerectomies were studied ultrastructurally.

RESULTS

Best-corrected visual acuity improved to RE, 20/60 from 20/100 preoperatively; the anterior chamber deepened, and the choroidal detachment resolved. Histopathologic studies of each of the three scleral layers disclosed abnormal collagen fibrils that were frayed, split, and contained lightly stained cores.

CONCLUSION

New findings include the identification of collagen with lightly stained centers and identification of differences in collagen morphology in different areas of the sclera in a nanophthalmic eye.

Culture of human retinal pigment epithelial cells from peripheral scleral flap biopsies

PURPOSE

We studied various methods for harvesting retinal pigment epithelium (RPE) biopsies from cadaver human eyes of donors over age 60 years. Our goal was to harvest cells for possible autologous RPE cell transplantation in patients with age-related macular degeneration and to test the viability of the RPE after isolation by evaluating explant growth in culture.

METHODS

Choroid-RPE biopsies were excised from enucleated human eyes. The RPE was separated from the choroid by treatment with type IV collagenase. RPE patches were cultured. After 100-500 cells had grown out from the explant, the primary cultures were passaged.

RESULTS

There was no clear effect of donor age on the ability to establish primary RPE cultures with good morphology from biopsies 2 x 2-10 x 10 mm2 in size. Biopsies 6 x 6 mm2 or larger produced satisfactory primary cultures more than 70% of the time. The number of viable RPE cells (defined as the number of cells adherent to the culture dish 24 h after plating) obtained after enzymatic separation of the RPE and choroid was an important determinant of our ability to establish primary cultures and passage the cells. Primary cultures with good cellular morphology were obtained 100% of the time when RPE explants > 4 mm2 in size were obtained from the biopsy specimen. Seventy-three percent of the biopsies yielding explants > 4 mm2 in size were successfully passaged.

CONCLUSIONS

These results suggest that peripheral scleral flap biopsies in aging donors can be used to establish RPE explant primary cultures. These cultures may be suitable as a source for autologous RPE transplantation in patients.

A novel pulse-echo technique for medical three-dimensional imaging

A new pulse-echo imaging technique for close near-field applications is proposed. Based on the theory developed for the continuous-wave automatic focusing technique (CWAFT), it uses instead, a frequency-domain phase compensation through a convolutional mechanism. In addition, the scanned frequencies of the transmitted CW signals are sent simultaneously in a pulse that is used for the data acquisition and processing. The pulse-echo nature of this technique makes it a candidate for further development and evaluation for ultrasonic three-dimensional (3-D) medical imaging and nondestructive testing. Furthermore, the "spike-like" nature of the back propagator in the frequency domain is used to half the data acquired. This alleviates most of the drawbacks of the CWAFT in data acquisition and processing. Simulation results are presented for both two-dimensional (2-D) and 3-D targets.

Treatment of presumed fungal endophthalmitis with oral fluconazole

Amphotericin B is the usual treatment for fungal endophthalmitis, but its toxicity and lack of oral bioavailability may limit its use in some patients. The authors report the successful management of two cases of presumed metastatic fungal endophthalmitis with oral fluconazole, a bis-triazole compound with a broad antifungal spectrum.