Background: The intensity of nociceptive stimuli reflects the severity of tissue injury. The anaesthetic requirement and stress hormonal responses were determined to learn whether they differ according to different surgical approaches (anterior vs. posterior) during the spinal surgery. Methods: Patients undergoing lumbar spine surgery without neurological deficits were divided into two groups: one having posterior (n 5 13) and the other having anterior fusion (n 5 13). The end-tidal sevoflurane concentrations (ET SEVO ) required to maintain the bispectral index score at 40-50 were determined. Mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), serum osmolality and plasma concentrations of catecholamines, cortisol and vasopressin (AVP) were measured. Results: There were no differences in MAP, HR, CVP and serum osmolality between the groups. ET SEVO was higher in the anterior than in the posterior group (Po0.05). The plasma concentrations of norepinephrine and cortisol increased in both groups during the surgery, whereas those of epinephrine remained unchanged. AVP concentrations increased during the surgery in the anterior group, and remained unaltered in the posterior group. The anterior group needed more analgesics (Po0.01) during the first 1 h after the operation. Conclusions: The anterior approach required a deeper level of anaesthesia while undergoing spinal surgery and more use of post-operative analgesics than the posterior approach. It was also associated with a more pronounced AVP release during the surgery.

Purpose: To establish whether the effect of fractionating radiation modifies the effects of ultraviolet (UV) radiation on epidermal melanocytes, we compared the clinical and histological effects of single high dose radiation against repeated intermediate to low dose radiation on epidermal melanocytes. Methods: Three minimal erythema UV doses (MED) were administered to three sites on the buttocks of healthy volunteers. One site was irradiated with 0.5 MED UV every day for 6 consecutive days, another site was irradiated with 1 MED UV every second day, and a third site received a single dose of radiation with 3 MED UV. The treatment was replicated on the other buttock. For the evaluation of UV‐induced erythema and pigmentation, erythema and melanin indices were measured at 2 and 14 days post‐irradiation. For purposes of histological evaluation, tissue specimens taken from each irradiated site at 2 and 14 days post‐irradiation and were stained with monoclonal antibodies against Mel‐5, HMB‐45 and tyrosinase. Fontana‐Masson silver staining, DOPA staining and split DOPA reactions were also performed. Results: At 14 days post‐irradiation, UV radiation induced melanocyte activation, proliferation and melanogenesis in proportion to the radiation dose administered to each fraction. The most prominent responses were observed after single high doses of radiation. Conclusion: When the total administered dose is identical, fractionation of radiation dose diminishes the effects of UV radiation on epidermal melanocytes. Furthermore, long, uninterrupted doses of UV radiation were found to more effective in inducing melanogenesis and melanocyte activation.