Skin cancers at Tertiary Referral Skin Hospital in Singapore

BACKGROUND: Skin cancer is the seventh most common cancer in Singapore. This study was performed to determine the pattern of skin cancers seen in a tertiary referral skin hospital. METHODS: Histologically confirmed skin cancers, seen between 1980 and 1991, were analyzed according to age, sex, race, site, and presence/absence of preexisting skin conditions. RESULTS: Of a total of 520 patients, the commonest skin cancer was basal cell carcinoma (BCC) (36.5%), followed by squamous cell carcinoma (SCC) (24.4%), Bowen's disease (16.7%), and mycosis fungoides (9.0%). Malignant melanomas (2.7%) were rare. The sharp increase (26.2%) in BCC in the recent 3 years was largely contributed by a fivefold increase of non-resident Caucasian patients with BCC. All types of skin cancers were more common in Chinese (78.1%) and less frequent in the more pigmented races (9.4%). The men to women ratio was 1.72:1. The peak age distribution was in the 51-70-year group, with the exception of mycosis fungoides (31-50 years). The commonest site involved in BCC was the head and neck (67.0%) and in Bowen's disease the trunk (33.3%). Squamous cell carcinoma was found on the head and neck and the lower extremities with equal frequency (29.3%) and 46.2% of all SCC on the lower extremities occurred in leprosy patients with chronic trophic ulcers. Of patients with Bowen's disease involving the nonsunexposed parts (trunk and upper extremities), 42.6% had probable arsenic exposure evident either from the history or clinical examination. Malignant melanomas were commonly located on the foot (71.4%). CONCLUSIONS: The commonest skin cancers seen were BCC, SCC, Bowen's disease, and mycosis fungoides. There were differences in the site distribution of SCC, Bowen's disease, and malignant melanomas in our study when compared to studies in Caucasians.     

Expression of lysyl oxidase from cDNA constructs in mammalian cells: the propeptide region is not essential to the folding and secretion of the functional enzyme

Rat aortic lysyl oxidase cDNA was expressed under a metallothionein promoter in Chinese hamster ovary cells using a dihydrofolate reductase selection marker. One methotrexate-resistant cell line, LOD-06, generated by transfecting with full-length cDNA, yielded lysyl oxidase proteins consistent with the 50 kDa proenzyme and a 29 kDa mature catalyst. A second cell line, LOD32-2, was generated by transfection with a truncated cDNA lacking sequences which code for the bulk of the propeptide region. Both cell lines secreted apparently identical, 29 kDa forms of mature lysyl oxidase each of which catalyzed the deamination of human recombinant tropoelastin and alkylamines, consistent with the known specificity of lysyl oxidase. The secreted enzyme forms were inhibited by chemical inhibitors of lysyl oxidase activity, including beta-aminopropionitrile, phenylhydrazine, ethylenediamine, alpha, alpha'-dipyridyl, and diethyldithiocarbamate. Sensitivity to these agents is consistent with the presence of copper and carbonyl cofactors in the expressed enzymes, characteristic of lysyl oxidase from connective tissues. These results indicate the lack of essentiality of the deleted proprotein sequence for the proper folding, generation of catalytic function, and secretion of lysyl oxidase.     

Primary duodenal adenocarcinoma: a ten-year experience with 79 patients

The comet assay is frequently used to measure DNA damage in individual cells. In order to better understand the mechanisms behind the technique, we have studied the behaviour of DNA under different electrophoresis conditions in mammalian cells exposed to gamma radiation. The comet tails obtained after neutral electrophoresis seem to consist of DNA loops which are attached to structures in the nucleus, since the DNA cannot move in the second direction after two-dimensional electrophoresis. When the DNA is labelled by a short pulse, microautoradiography reveals that all label appear in the head of the comets when neutral electrophoresis is applied. After chase incubation, the label moves out into the tails. This gives further support to the view that the DNA loops are fixed to some structure in the nucleus where also the DNA synthesis takes place. Under alkaline electrophoresis conditions, however, the entire comet tails move in the new electrophoresis direction. Thus, it appears that the alkaline comet tails consist of free DNA fragments. Further, the effects of alkaline concentration and sodium chloride during unwinding and electrophoresis are discussed. Throughout the study, a protocol for drying and fixation of the comets has been used.     

The biotype and genetic characteristics of an isolate of the cowpox virus causing infection in a child

The study included 138 patients operated on for endo-extracellular pituitary adenomas which extend both intracranially and into the structures of the base of the skull. Operations via transcranial and transsphenoidal access to various tumor sites were performed in 38 patients (a main group), while 100 patients (a control group) underwent one of these operations. Two-stage operations, followed by removal of the suprasellar and basal regions of a tumor, are expedient for enhancing the efficiency of surgical treatment, reducing the incidence of complications associated with traumatic attempts at removing tumor parts hard-to-reach by transcranial or transsphenoidal approaches, as well as at reducing the number of relapses. At the first stage of surgical treatment it is advisable to make an intervention via transcranial access especially in cases of complex configuration of the suprasellar part of a tumor. The recommended interval between transcranial and transsphenoidal surgeries is 3-5 months. Two-stage surgical treatment does not lead to significant structural changes and to the increased number of complications, and to higher mortality rates as compared to one-stage surgery (transcranial or transsphenoidal surgeries alone).     

Cytotoxic activity of platelets and peripheral blood mononuclear cells from oncology patients and healthy donors

Testicular germ cell tumour is said to be a model for curable neoplasm. However, the prognosis of primary extragonadal germ cell tumour does not appear to be as promising. Though similar in histology, the biology of primary extragonadal germ cell tumour is different as exemplified by the patients in this review. Eight patients with primary mediastinal germ cell tumours were treated with intensive cisplatin-based chemotherapy. All, except one, had non-seminomatous components. The poor prognosis of mediastinal germ cell tumour is due to a combination of poor treatment results with the cisplatin-based regimen and the development of non-germ cell and haematological malignancies.