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.

Prolonged deposition of heavy metals in infiltration facilities and its possible threat to groundwater contamination.

A field investigation of infiltration facilities, built two decades ago in Tokyo, was carried out and sediment samples were collected from 12 infiltration inlets of three different locations. Heavy metals contents in the inlet sediment, road dusts and soils samples were analysed and compared. The particle size distribution analysis showed its variation in depth as well as from inlet to inlet. The nature of organic substances present in sediment found changes in particle sizes as well as in depth. The heavy metals content in the sediment samples ranged from 6-143 (Cr), 1-84 (Ni), 49-331 (Cu), 210-2186 (Zn) and 2-332 (Pb) microg/g. The heavy metal content ranges were similar to road dust, which indicated road dust as a possible source for sediment for the infiltration inlets. The lower heavy metals content in many sediment samples than the soil indicated possible release/desorption of heavy metals under newly created environments such as an anaerobic environment. Among the heavy metals there was a relatively good relationship between Cu and Zn, indicating the existence of their common sources.

Model description of storage and infiltration functions of infiltration facilities for urban runoff analysis by a distributed model.

Although there have been simulation researches focusing on reduction of stormwater peak flow by introduced infiltration facilities, model simulation of dynamic runoff behavior is still limited for frequently occurring rainfall events with weak intensity. Therefore, dynamic simulation was carried out in two urban drainages with infiltration facilities incorporated with a distributed model using two methods for describing functions of infiltration facilities. A method adjusting effective rainfall model gave poor simulation of runoff behavior in light rainfalls. Another method considering dynamic change of storage capacity as well as infiltration rate gave satisfactory estimation of the runoff in both drainages. In addition, assumption of facility clogging improved the agreement between measured and simulated hydrographs in small and medium-sized rainfall. Therefore, the proposed method might be useful for quantifying the secondary effects of the infiltration facilities on groundwater recharge and urban non-point pollutant trapping as well as runoff reduction.

A long-term suspended solids runoff simulation in a highway drainage system.

A long-term monitoring investigation was carried out in a highway drainage system in Winterthur, Switzerland. Several runoff quality and quantity simulations were carried out using the distributed model 'InfoWorks-CS'. Serial rainfall monitoring data was used for investigation of SS runoff behavior from the highway. Under continuous rainfall conditions, the quantity simulation showed a good agreement with the measured hydrograph. However, in some cases where rainfall was not continuous, overestimation of the peak height was found at the later stage after the end of the rainfall. It was believed that the initial/depression loss on the road surface was recovered during the halting period of rainfall. The consideration of regenerated depression loss significantly improved runoff simulation results in the on-and-off type rainfall events. A single event quality simulation underestimated the SS load in light rainfall events. One of the reasons was possibly inadequate consideration of pipe sediment conditions. A long term simulation was carried out to establish the initial condition of surface and pipe sediment for the target event. The newly simulated pollutograph gave a good agreement with the measured one. It revealed that it was essential to consider appropriateness of the initial condition of pipe sediment as well as surface sediment.