Short Course Palliative Radiotherapy in Locally Advanced Squamous Cell Carcinoma of Head and Neck

This prospective cohort study was conducted at the Combined Military Hospital, Dhaka during January 2003to December 2005. Thirty patients with locally advanced stage III and stage IV squamous cell carcinoma ofhead and neck were treated with a short course palliative radiotherapy (30 Gray in 10 fractions over 2 weeks).All (100%) patients with pain and 90% of patients with dysphagia, dyspnoea and disturbed sleep had greaterthan 50% relief in symptoms after radiotherapy. Dysphonia and cough were satisfactorily relieved in morethan 60% of cases. Eight of 30 lesions in this study had complete response; 14 lesions had a partial response; 4lesions had no response; 2 lesions progressed under treatment. Response could not be assessed in two patients.Acute and late reactions were acceptable. After palliative radiotherapy 8(27%) patients were eligible for doseescalation and received further radiotherapy upto radical dose equivalent. It was concluded that short coursepalliative radiotherapy regimen evaluated is an effective treatment modality for sustained symptoms reliefwith good response rates and acceptable toxicity in locally advanced head-neck cancer.Key words: Palliation; radiotherapy; short course; head and neck cancer.DOI: 10.3329/jafmc.v6i1.5986Journal of Armed Forces Medical College, Bangladesh Vol.6(1) 2010 p.16-20

Insect metabolism of photoaldrin and photodieldrin

Photoaldrin and photodieldrin, sunlight products of adrin and dieldrin, are rapidly metabolized to a more toxic material by flies and mosquito larvae. It is suggested that this conversion is the cause for the enhanced toxicities of the photoproducts.

DDT-resistance in West African and Asian strains of Aedes aegypti (L.)

The yellow fever mosquito Aedes aegypti has developed resistance to DDT in the Caribbean region and in South-East Asia, but not in West Africa. Therefore West African strains were compared with South-East Asian strains for their response to laboratory selection with DDT. It was found that West African strains were much slower to respond initially, but eventually could build up a high degree of DDT-resistance. By crossing and backcrossing with a susceptible marker-gene strain, it was found that this resistance was due to a single gene linked with the gene y (yellow) on chromosome 2 at a cross-over distance of approximately 35 units in an Upper Volta strain as in a Bangkok strain; interstrain crosses indicated that the gene was the same as that in a Trinidad strain and in one from Penang. Dieldrin-resistance could be readily induced in the Upper Volta strain and proved to be due to a gene also linked with y but at a crossover distance of approximately 25 units, comparable to that in Caribbean strains previously studied. Material from Karachi, West Pakistan, developed a dieldrin-resistance also showing 25% crossing over with y, and a DDT-resistance also linked with this chromosome-2 marker gene.