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The ultrafast magnetization dynamics of thin Ni and Co films on Cu͑001͒ and of polycrystalline Ni surfaces was studied by pump-probe reflection second-harmonic generation, utilizing 150 fs/800 nm laser pulses. In all cases no delay between electron excitation and magnetization breakdown was observed within the experimental time resolution. An upper limit of such delay is 50 fs in case of bulk Ni surfaces. The recovery of magnetization follows the electron temperature relaxation during the first few picoseconds and thereafter cooling by regular thermal diffusion. ͓S0163-1829͑99͒50510-9͔

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We have previously reported that the cyclin D1 (CCND1) GG 870 genotype was associated with poorly differentiated tumors and reduced disease-free interval in patients with squamous cell carcinoma of the head and neck (SCCHN). We have now examined the association of this and a second CCND1 polymorphism with gene expression and outcome in SCCHN patients. Analysis of a CCND1 G/C 1722 polymorphism revealed that CCND1 CC 1722 genotype was associated with poorly differentiated tumors [P ‫؍‬ 0.005; odds ratio (OR), 5.7; 95% CI, 1.7 to 19.2), and reduced disease-free interval (P ‫؍‬ 0.003; Hazard Ratio (HR), 7.3; 95% CI, 1.1 to 27.2.) independently from the influence of CCND1 GG 870 genotype. Patients whose tumors were negative for cyclin D1 were associated with reduced disease-free interval (P ‫؍‬ 0.028; HR, 4.1; 95% CI, 1.4 to 14.2). Although G/C 1722 genotypes were not associated with expression, we found a significant trend between reduced expression of cyclin D1 in patients with the CCND1 GG 870 genotype (P ‫؍‬ 0.04). Splicing of CCND1 mRNA in head and neck tissues was modulated by CCND1 A/G 870 alleles, thus CCND1 transcript a was spliced equally from CCND1 A 870 and G 870 alleles, whereas CCND1 transcript b was spliced mainly from the CCND1 A 870 allele. Our analysis has also identified differences in cyclin D1 genotype and protein expression and the pathogenesis of SCCHN in males and females. Thus, CCND1 CC 1722 genotype was more common in female patients (P ‫؍‬ 0.019; OR, 3.3; 95% CI, 1.3 to 10) and cyclin D1 expression was more frequent (chi-square 1 , 3.96; P ‫؍‬ 0.046) and at higher levels (P ‫؍‬ 0.004) in tumors from female patients. In summary, our data show that the two CCND1 polymorphic sites are independently associated with tumor biology and clinical outcome. CCND1 A/G 870 alleles affect gene expression in head and neck tissues. We also provide preliminary evidence that the molecular genetics of SCCHN development may be influenced by patient gender. (Am J Pathol 2001, 159:1917-1924)