Incidence of metastasis to level V lymph nodes in clinically positive necks among Sri Lankan patients with oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) remains the most common cancer among males in Sri Lanka. Metastasis to neck is a crucial prognostic factor. A modified radical/radical neck dissection including levels I -V, was performed in patients with OSCC who had a clinically positive neck (cN+). Currently, evidence suggests that sparing level V in a cN+ may be justified due to less chance of metastasis in early stages of the disease. To the best of our knowledge, the incidence of metastasis to level V in patients with cN+s has not been previously investigated in a Sri Lankan context. We aimed to determine level V lymph node metastasis and related clinicopathological indicators in cN+s in patients with OSCC. A multicentre retrospective study investigated postoperative biopsy reports of 187 patients for five years. OSCC patients with cN+s who underwent neck dissections of levels I-V were included. Only 6.4% of patients had histopathologically positive level V lymph nodes. A total of 127 lymph nodes were harvested from level V of those who showed level V positivity and out of them 68 were positive with a third of cases showing extranodal extension (ENE). The buccal mucosa (n=4) and lateral aspect of the anterior two thirds of the tongue (n=4) were the common primary sites for level V metastasis. In patients who showed positivity in levels III and IV, a considerably higher probability of level V nodes being positive was seen, which was statistically significant (p = 0.0001). We have concluded that the routine performance of a modified radical/radical neck dissection for cN+s should be stopped, as the incidence of Level V positivity is significantly low. Assessing the cN+ for N stage, status of levels III and IV, pattern of invasion, differentiation, and the site may be used instead as predictors for level V positivity.

Cyclin D1 overexpression vs. retinoblastoma inactivation: implications for growth control evasion in non-small cell and small cell lung cancer.

The cyclin-dependent kinases and their associated regulatory cyclins control cell cycle progression and cell growth. Antibodies against these proteins were used to determine their levels in several lung tumor-derived cell lines and a "normal" immortalized bronchoepithelial cell line in order to investigate their potential roles in the etiology of lung cancer. All the cell lines expressed roughly equal levels of cdk-1; cdk-2; PSTAIRE-sequence containing kinases; proliferating cell nuclear antigen; and cyclins A, B1, and E. Cyclin D1, however, was present at 4- to 100-fold higher levels in 11 of 12 non-small cell lung cancer cell lines than in the bronchoepithelial line and all but one of the small cell lung cancer lines. Furthermore, immunoblots of the retinoblastoma gene product, pRB, revealed a perfect correlation between pRB levels and tumor type with normal levels of phosphorylation-competent pRB in all of the non-small cell lung cancer lines and undetectable levels of pRB in all of the small cell lung cancer lines. These data suggest the possibility that small cell and non-small cell lung cancer may evade normal growth controls by different mechanisms: loss of the proliferation inhibitor pRB in small cell lung cancer and overexpression of the growth promoting cyclin D1 in non-small cell lung cancer.

Tryptophan enhancement of somatic embryogenesis in rice.

Cereal embryos can produce two types of callus. One type, termed "embryogenic," consists of small meristematic-like cells and gives rise to many plants by somatic embryogenesis if placed on a suitable regeneration medium. The other is termed "nonembryogenic" and consists of long tubular cells which gives rise to few or no plants. High concentrations of tryptophan increased the formation of embryogenic callus in three rice cultivars (Oryza sativa L. Calrose 76, Pokkali, and IR 36) but not in four others (Mahsuri, Bg 400-1, H(4), and Giza 159). The best concentration of tryptophan for Pokkali and Calrose 76 was 100 micrograms per milliliter, and for IR 36, 50 micrograms per milliliter. Indoleacetic acid at 100 micrograms per milliliter promoted an effect similar to that of tryptophan on Calrose 76. The difference between japonica (Calrose 76, Giza 159) and indica (Pokkali, IR 36) varieties is not the causal factor for the difference in response to tryptophan. Kinetin does not appear to be a requirement for embryogenic callus formation in Calrose 76. Plant regeneration from Calrose 76 embryogenic callus occurred at low levels in media containing no hormones. 6-benzyladenine, or 2,3,5-triiodobenzoic acid but not indoleacetic acid at 0.1 to 0.5 micrograms per milliliter significantly increased regeneration.