Healing of cervical epithelium after laser ablation of cervical intraepithelial neoplasia.

Healing of cervical epithelium was studied in 30 patients after destruction of cervical intraepithelial neoplasia using a carbon dioxide laser. Repeated examinations, using photography and colposcopically directed punch biopsies, were made from the eighth to the 32nd day after treatment. The biopsy specimens were submitted to examination by light and transmission electron microscopy. There was complete epithelial cover of the laser induced craters in all patients by 28 days. The base of the crater and endocervical edge became covered by columnar epithelial cells originating in endocervical crypts, while the vaginal edge re- epithelialised by an ingrowth of the surrounding squamous epithelium. Squamous metaplasia of the new columnar epithelium was a common observation as early as eight days after treatment. There was no evidence for a stromal contribution to epithelial cover.

Field Evaluation of Transgenic and Classical Sources of Wheat streak mosaic virus Resistance.

The development of wheat (Triticum aestivum L.) cultivars that are resistant to Wheat streak mosaic virus (WSMV), yet competitive in yield under nondiseased conditions, is an objective for breeding programs in the Great Plains. This field study was conducted to compare classical and transgenic sources of resistance to WSMV. Three sets of germplasm were evaluated. These included adapted cultivars with various levels of tolerance, transgenic wheat lines containing viral coat protein or replicase sequences from WSMV that showed resistance in greenhouse trials, and germplasm with resistance to WSMV due to a translocated segment of chromosome 4Ai-2 from Thinopyrum intermedium (Host) Barkworth and Dewey containing Wsm1. A replicated field trial was conducted at Bozeman, MT, over a two-year period to evaluate the effectiveness of these different sources of resistance to mechanical inoculation of WSMV. Adapted cultivars differed in their ability to tolerate WSMV with mean reductions in yield over the two years ranging from 41 to 74%. Incorporation of the replicase or coat protein gene from WSMV did not provide field resistance to viral infection and in general, transgenic lines yielded less than their parent cultivar, 'Hi-Line'. Wheat-Thinopyrum lines positive for a DNA marker linked to the Wsm1 gene had significantly reduced yield losses ranging from 5 to 39% compared with yield losses of 57 to 88% in near isogenic lines not having the Wsm1 gene. Yield of lines with Wsm1 in the absence of disease ranged from 11 to 28% less than yield of lines without Wsm1. Our results suggest Wsm1 provides the best source of WSMV resistance but a yield penalty may exist because of the presence of the translocation.