Induction of oxidative DNA base damage in human skin cells by UV and near visible radiation

The premutagenic oxidative DNA base damage, 7,8-dihydro-8-oxoguanine, is induced in human skin fibroblasts by monochromatic radiation ranging from a UVB wavelength (312 nm) up to wavelengths in the near visible (434 nm). The oxidative damage is not generated by absorption of radiation in DNA but rather by activation of photosensitizers generating genotoxic singlet oxygen species. The spectrum for the yield of the oxidative damage in confluent, non-growing, primary skin fibroblasts shows that it is UVA (above 334 nm) and near visible radiations which cause almost all of this guanine oxidation by natural sunlight in the fibroblast model. We estimate that the total amount of oxidation of guanine induced by sunlight in fibroblasts in the epidermis of the skin equals or exceeds the amount of the major type of direct DNA damage, cyclobutane pyrimidine dimers. In rapidly dividing lymphoblastoid cells, no oxidative guanine damage was induced. However, in melanoma cells almost as much damage as in non-growing fibroblasts (1.1 per 10(4) guanine bases after 1200 kJ/m2 UVA) was found. We conclude that oxidative DNA base damage can probably contribute to the induction of both non-melanoma and melanoma skin cancer by sunlight.      

Physiological anticoagulants and activated protein C resistance in childhood stroke

Immunological and functional protein S, protein C and antithrombin III levels and anticoagulant responses to activated protein C were measured in 24 patients with stroke in childhood. No hereditary deficiencies were found. The protein S levels in healthy controls of younger age did not differ from the adult levels. For optimal screening of protein S deficiency, measurements using functional as well as immunological assays are recommended. Appropriate criteria for the diagnosis of the deficiencies must be carefully applied if unnecessary anxiety and inappropriate treatment of children are to be avoided.     

Nutritional factors and thalassaemia major

Abnormal growth is a common feature of thalassaemia major in children. In an attempt to determine whether it has a nutritional cause, 12 children aged 1 to 3 years with thalassaemia major were studied under metabolic ward conditions. Nutritional status was assessed by anthropometry and biochemistry before and after an intensive nutrition regimen. Five children had wasting or stunting on admission. As a result of the nutrition intervention, mean weight for height improved significantly. The mean height increase of 0.4 cm after one month was not significant. Plasma zinc, depressed in half the children on admission, improved, as did alpha tocopherol, while copper decreased. Plasma insulin-like growth factor-I also increased commensurate with improved growth. Fat absorption was normal in all children. Undernutrition is an important cause of associated growth disturbances in children with thalassaemia major. Malnutrition was primarily caused by inadequate nutrient intake, as indicated by the capacity to gain weight appropriately when provided with nutrition support, and by the absence of intestinal malabsorption. While long term studies are required to determine if nutritional support will prevent stunting, these results underscore its central role in preventing nutritional deficiencies and in promoting normal growth in thalassaemic children.     

Direct demonstration of transsynaptic degeneration in the human visual system: a comparison of retrograde and anterograde changes

Transneuronal degeneration of retinal ganglion cells was directly demonstrated in a patient who had unilateral removal of the striate cortex forty years prior to necropsy. For comparison, another case is presented showing anterograde transneuronal atrophy forty years after enucleation of one eye.     

Occult otologic fistulas as a cause of recurrent meningitis

OBJECTIVE: Occult perilymph fistulas may be the cause of unexplained non-epidemic meningitis. MATERIAL AND METHOD: To review the case reports of 5 patients (3 females and 2 males aged 4-56) presenting with unexplained meningitis. All had sensorineural hearing loss of variable duration. RESULTS: All patients were submitted to CT, MRI and MRI cisternography. All underwent exploratory tympanotomy to seal the fistula. In all patients the fistula could be located and sealed. All had no further attacks of meningitis and those who had serviceable hearing did not show any further deterioration. CONCLUSION: In any case of recurrent meningitis an occult perilymph leak should be sought. A high degree of suspicion should exist if there are auditory or vestibular symptoms. Detecting and sealing of the defect will protect the patient against further attacks and deterioration of hearing.     

Endoscopic repair of bilateral congenital choanal atresia

OBJECTIVE: The literature about endoscopic repair of bilateral choanal atresia is scarce. The advantages and difficulties encountered with this technique are discussed. STUDY DESIGN: Prospective case series in a tertiary care center. METHODS: Nine infants with bilateral choanal atresia underwent transnasal endoscopic repair. On computed tomography scans, six had mixed atresia and three had bony atresia. Extra-long burrs, ear curettes, and dissectors all have been used with 4- and 2-mm, 0 degrees telescopes. The neochoana has been stented for 5 to 8 weeks. All cases were examined with the endoscope on removal of the stent; any granulation or polyps were removed at that time. RESULTS: Five cases remained patent after removal of stenting. Two patients required revision surgery because of repeat stenosis; one case remained patent and the other had repeat stenosis on one side. One infant died because of unrelated medical problems that occurred later. In one case the atretic tissue was thick, and the procedure was stopped because of bleeding; the infant died in the postoperative period after resuscitation. CONCLUSION: Careful review of the computed tomography scan and experience with endoscopic nasal surgery makes the transnasal endoscopic treatment a safe and effective approach for managing bilateral choanal atresia.     

Study of the Impact of Deltamethrin Impregnated Mosquito Nets on Malaria Incidence at a Military Station

Deltamethrin impregnated mosquito nets have been successfully used all over the world to combat malaria. To study the efficacy of these mosquito nets in the service conditions of Armed Forces, a field trial of Deltamethrin impregnated mosquito nets was carried out at Military Stations ‘A’ (trial station) and B (control station) between July 96 to June 99. July 96-June 97 was the pretrial year during which base line data was collected for malaria incidence. Three rounds of Deltamethrin impregnation of the mosquito nets were done in the trial station for the actual trial duration (July 97-June 99) in lieu of residual spraying. Antimalaria measures including residual spray were continued as usual in the control station. The intervention led to a significant decline in slide positivity rate and malaria incidence in the trial station. Malaria cases declined by 87% in the trial station whereas the control station noticed an increase by 75% at the end of the trial.Key Words: Deltamethrin impregnated mosquito nets, Malaria control