Calculations of flow resistance in the juxtacanalicular meshwork

The structure of the juxtacanalicular meshwork (JCM) was analyzed morphometrically, and the resulting data were used to calculate the resistance to flow through this tissue. Two models of the JCM were presented and compared. In the first (Model A), aqueous humor was assumed to flow via open channels within a solid framework, while, in the second (Model B), these open spaces were assumed to be filled with extracellular matrix gel. An expression giving the resistance of such a gel as a function of gel concentration was presented and tested on corneal and scleral stroma. Morphometry of normal and glaucomatous human eyes showed that Model A underpredicted the resistance of the JCM by factors of 10-100, suggesting that a GAG or proteoglycan gel may control the flow resistance of this tissue. This was supported by Model B, which showed that measured bulk concentrations of GAGs were consistent with gel concentrations needed to account for the estimated resistance of the JCM in vivo. Some limitations and implications of Model B were discussed.     

Narrowband UVB therapy for vitiligo: does the repigmentation last?

BACKGROUND: Since 1997, a number of trials have shown promising results in treating generalized vitiligo with narrowband ultraviolet B (UVB) both in adults and children. However, there is little knowledge concerning the duration and permanency of the treatment-induced repigmentation. OBJECTIVE: Our main objective was to perform a follow-up trial of successfully treated patients receiving narrowband UVB for generalized vitiligo. METHODS: We have investigated to what degree the treatment-induced repigmentation remains stable for up to 2 years post-treatment. We performed an initial open trial including 31 patients with generalized vitiligo. They received narrowband UVB thrice weekly for up to 12 months. Patients experiencing > 75% repigmentation were defined responders and were included in the follow-up trial. Responders were followed every 6 months for up to 2 years after cessation of treatment. We observed the pigmentation status and registered any changes indicating loss of pigmentation and relapse. RESULTS: Eleven of the 31 treated patients were included in the follow-up trial. Six patients had relapse and five patients had stable response 24 months after cessation of treatment. Four out of six relapses were within 6 months post-treatment. CONCLUSION: In our study population of 31 patients with generalized vitiligo, five patients (16%) experienced > 75% stable repigmentation 2 years after cessation of a treatment programme of up to 1 years narrowband UVB therapy.     

Ongoing pregnancies after intracytoplasmic injection using cryopreserved testicular spermatozoa

We report two clinical pregnancies occurring after intracytoplasmic sperm injection (ICSI) using cryopreserved spermatozoa obtained from testicular biopsy, made in two different infertility situations in our clinic. The first patient showed a secretory azoospermia associated with elevated serum follicular stimulating hormone (FSH) level and spermiogenesis maturation arrest. The second patient was affected by azoospermia resulting from bilateral epididymal obstruction. Spermatozoa present in the wet preparation of testicular biopsy made on the day of scrotal exploration were cryopreserved within the testicular tissue for both men. Intracytoplasmic injections were performed at a later date, using spermatozoa prepared from frozen-thawed tissues. In each case, three embryos were obtained and transferred in utero. The transfers resulted in a twin pregnancy for the first case, and in a singleton pregnancy for the second. Living foetuses were seen in the ultrasound scan at the 7th week and both pregnancies are proceeding to date beyond 30 weeks without complications.      

Enhanced in vitro proliferation and in vivo tumorigenic potential of mammary epithelium from BALB/c mice exposed in vivo to gamma-radiation and/or 7,12-dimethylbenz[a]anthracene

Virgin female BALB/c mice were exposed in vivo to whole body gamma-radiation and/or to 7,12-dimethylbenz[a]anthracene (DMBA) p.o. Mammary epithelial cells were isolated and assayed for carcinogen altered cell populations both in vitro by an epithelial focus assay and in vivo by injection into cleared fat pads of syngeneic host mice. Five groups of mice were exposed as follows: (a) sham controls; (b) 50-rad gamma-radiation; (c) 100-rad gamma-radiation; (d) 75 micrograms DMBA; or (e) 50-rad gamma-radiation followed in 1 week by 75 micrograms DMBA. Mammary epithelial cells were isolated and assayed at 24 h and at 1, 4, 16, and 52 weeks after in vivo exposure. Four to 12 mice per treatment per time point were individually assayed. Altered in vitro growth potential was characterized by the proliferation of carcinogen exposed (but not control) cells as epithelial foci which persisted at least 12 weeks in primary culture. Epithelial foci which could then be subcultured at least four times were termed subculturable epithelial foci. Altered in vivo morphogenic potential was characterized by dysplastic or neoplastic growth in host fat pads. With increased time in situ between exposure and assay, cell populations emerged which exhibited both increased in vitro subculturability and enhanced tumorigenic potential including a host response upon injection in vivo. Further, combined radiation and DMBA resulted in higher frequencies of subculturable epithelial foci than either treatment alone. The relevance of these progressive cellular changes to the process of mammary tumor development is discussed.