Although weak interactions play subtle but important roles in dictating protein structures, their experimental detection is nontrivial. From NOE experiments we provide direct evidence for the presence of CH···π interaction, operational between the C(α)-H of the first Pro and the aromatic (Aro) side chain of Xaa, in a peptide series with the general sequence Ac-Pro-Pro-Xaa-NH(2). Indirect evidence of CH···π interaction is provided from ring current-induced upfield displacement of Pro(1) C(α)-H chemical shifts and restriction of side-chain (χ1) rotation of Xaa. A consequence of this interaction is the enhanced stability of the Pro-cisPro conformer in Ac-Pro-Pro-Xaa-NH(2) when Xaa is aromatic. The free energies associated with trans to cis transformation of the Pro-Pro moiety are 0.35, 0.59, 0.64, and 0.82 kcal/mol when Xaa is Tyr, Trp, Phe, and His (pH of 8.4), respectively. In comparison, the corresponding free energy is ∼1.55 kcal/mol when Xaa is nonaromatic. The observed population of Pro-cisPro-His and the pH-induced perturbation of electron density of the His side chain were correlated, providing further evidence for a direct role of CH···π interaction in modulating the stability of Pro-cisPro population in Ac-Pro-Pro-Aro-NH(2). Our study establishes Pro-Pro-Aro to be a new sequence motif that can stabilize Pro-cisPro peptide bonds. This study not only identifies a new structurally biased sequence motif but also directly demonstrates the role played by CH···π interactions in subtly altering conformational preferences of three-residue peptide sequences with implications on the role played by cis-peptide bonds in unfolded proteins.

Conjugated linoleic acid (CLA) reduces mammary tumorigenesis in rodent models, induces apoptosis in rodent mammary tumor cell lines, and decreases expression of antiapoptotic bcl-2 in rat mammary tissue. This investigation focused on the cell mechanisms underlying the antitumor effects of CLA. Changes (mRNA, protein) in expression of major proapoptotic p53, p21WAF1/CIP1, bax, bcl-Xs genes, and the antiapoptotic bcl-2 gene were observed in malignant MCF-7 and MDA-MB-231 cells and in benign MCF-10a human mammary tumor cells in culture. CLA, but not linoleic acid (LA), inhibited proliferation in all cells; CLA mix was most effective. CLA increased DNA damage (apoptosis). CLA increased mRNA expression of p53 and p21WAF1/CIP1 (three- to fivefold and twofold, respectively) but either decreased bcl-2 by 20-30% or had no effect in MCF-7 and MCF-10a cells, respectively; protein expression reflected mRNA values. In MDA-MBA-231 (mutant p53) cells, mRNA for p53 was not changed, but p21WAF1/CIP1 and bcl-2 mRNA was increased. Protein expression largely reflected mRNA changes but, surprisingly, CLA completely suppressed mutant p53 protein in MDA-MB-231 cells. Apparent antiapoptotic effects of increased bcl-2 expression in MDA-MBA-231 cells were countered by increased proapoptotic p21WAF1/CIP1, Bax, and Bcl-Xs proteins. Findings indicate that CLA elicits mainly proapoptotic effects in human breast tumor cells through both p53-dependent and p53-independent pathways, according to cell type.

Objective To establish the prognostic value of knowledge of sentinel node status in melanoma. Design Single centre prospective observational study, with sentinel nodes identified by lymphoscintigraphy, probe, and intraoperative blue dye and examined by both conventional histopathology and immunopathology. Setting Specialist surgical service in west of Scotland. Participants 482 patients with melanoma who consented to sentinel node biopsy in 1996-2003. Main outcome measure Time to recurrence of or death from melanoma. Results Of 472 patients who consented to sentinel node biopsy and in whom at least one sentinel node was identified, 367 (78%) had no tumour in the sentinel node. At mean follow-up of 42 months, 299 (82%) of this group were alive and free from disease, 24 were alive with melanoma recurrence, and 31 had died of melanoma. Of 105 patients with a positive sentinel node biopsy, 44 (42%) were alive and disease free, 12 were alive with recurrence, and 46 had died of melanoma. The survival difference between patients who were negative and those who were positive for tumour in the sentinel node was highly significant at all thickness levels over 1.0 mm (P < 0.001). Multivariate analysis showed that sentinel node status was independent of tumour thickness and ulceration. 71/105 (68%) patients with a positive sentinel node had a negative completion lymphadenectomy, and 44/71 (62%) were alive and disease free at follow-up; 34 patients with a positive sentinel node had further nodes involved, and only 4 (12%) were disease free (P < 0.001). 16 patients (13 sentinel node biopsy positive; 3 negative) died of other causes.

Endovascular repair of abdominal aortic aneurysm is a common procedure and not without complications. The aim of this study was to evaluate the early results of the Anaconda endograft (Vascutek Ltd., Inchinnan, Scotland, UK) in 106 patients in three hospitals in the west of Scotland. A prospective registry of 106 consecutive patients undergoing endoluminal repair of their abdominal aortic aneurysms using the Anaconda device was set up to record the clinical outcomes, with a mean follow-up of two years. There was no 30-day perioperative mortality in the 106 patients. Only type II endoleaks were detected on serial computed tomography scanning at follow-up. Technical success was achieved in 99% (105/106) in this study; one patient was converted to open surgical repair. Two cases of proximal device migration (>1 cm) were detected at one month and 19 months, respectively, with no associated endoleak or sac enlargement. Five cases of endograft limb thrombosis were noted in this study. Our early clinical experience with the Anaconda endograft compares favourably with other commercially available endografts in the treatment of abdominal aortic aneurysms. The main advantages of this device are that it is re-deployable and that it has a magnetic wire system which makes it easy to implant.

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