A microbiologic and ultrastructural investigation of germ-tube formation by oral strains of Candida tropicalis

Presumptive germ tube-positive and -negative Candida tropicalis strains have been obtained from both normal children and patients who have candidiasis. Examination of these strains by conventional microbiologic tests confirmed them to be C. tropicalis. Ultrastructural examination of the filaments produced by the positive strains revealed two types: true germ tubes and those with basally constricted cytoplasm. A fluctuation analysis of the positive strains showed two subgroups: germ tube-positive and -negative. It is suggested that C. tropicalis strains may be divided into germ tube-positive and -negative strains, and that germ-tube formation must therefore not be used as a sole criterion for identification of C. albicans.     

Widespread integration and survival of adult-derived neural progenitor cells in the developing optic retina

Adult rat hippocampus-derived neural progenitor cells (AHPC) show considerable adaptability following grafting to several brain regions. To evaluate the plasticity of AHPCs within the optic retina, retrovirally engineered AHPCs were grafted into the vitreous cavity of the adult and newborn rat eye. Within the adult eye, AHPCs formed a uniform nondisruptive lamina in intimate contact with the inner limiting membrane. Within 4 weeks of grafting to the developing eye, the AHPCs were well integrated into the retina and adopted the morphologies and positions of Müller, amacrine, bipolar, horizontal, photoreceptor, and astroglial cells. Although the cells expressed neuronal or glial markers, none acquired end-stage markers unique to retinal neurons. This suggests that the adult-derived stem cells can adapt to a wide variety of heterologous environments and express some but not all features of retinal cells when exposed to the cues present late in retinal development.     

All-Optical Label Extractor/Eraser for In-Band Labels and 160-Gb/s Payload Based on Microring Resonators

Photonic integration of an all-optical packet switch (AOPS) is a crucial issue since it leads to a great reduction of volume, power consumption, and costs. Recently, a 1 times 4 AOPS was successfully demonstrated by using an all-optical label extractor/eraser. The label extractor/eraser was implemented by means of fiber Bragg gratings and optical circulators that prevent the photonic integration of the AOPS. Here, we demonstrate a passive and asynchronous photonic integrated all-optical label extractor/eraser by using narrowband silicon-nitride add-drop ring-resonators. By exploiting the narrow bandwidth of the drop port and pass-through port error-free simultaneous separation/erasing of the in-band labels from the 160-Gb/s packet payload was demonstrated without noticeable pulse-shape distortions.