[Successful breastfeeding after reduction mammaplasty]. / Succesvolle borstvoeding na borstverkleining.

OBJECTIVE: To determine if it is possible to successfully breastfeed after reduction mammaplasty with intact continuity between papilla and glandular tissue. DESIGN: Retrospective by use of a written questionnaire. METHOD: Between 1986 and 2000, 994 women under the age of 35 underwent a reduction mammaplasty at the Medical Centre in Leeuwarden, The Netherlands. They were all sent a questionnaire of which 585 were completed correctly and returned. RESULTS: Of the 585 women, 215 had had one or more children and 90 had started breastfeeding, 57 of whom were successful (63%). In non-operated women this figure is 69%. The advice to try to breastfeed was associated with a higher percentage of success than the advice not to try--78% and 42% respectively. CONCLUSION: It appears to be justified to encourage women who have had a breast reduction to attempt to breastfeed after the birth of a child.

The Mad1-Sin3B interaction involves a novel helical fold.

Sin3A or Sin3B are components of a corepressor complex that mediates repression by transcription factors such as the helix-loop-helix proteins Mad and Mxi. Members of the Mad/Mxi family of repressors play important roles in the transition between proliferation and differentiation by down-regulating the expression of genes that are activated by the proto-oncogene product Myc. Here, we report the solution structure of the second paired amphipathic helix (PAH) domain (PAH2) of Sin3B in complex with a peptide comprising the N-terminal region of Mad1. This complex exhibits a novel interaction fold for which we propose the name 'wedged helical bundle'. Four alpha-helices of PAH2 form a hydrophobic cleft that accommodates an amphipathic Mad1 alpha-helix. Our data further show that, upon binding Mad1, secondary structure elements of PAH2 are stabilized. The PAH2-Mad1 structure provides the basis for determining the principles of protein interaction and selectivity involving PAH domains.

[Transposition of the tendon of M. tibialis posterior an effective treatment of drop foot; retrospective study with follow-up in 12 patients]. / Transpositie van de pees van de M. tibialis posterior effectief bij een klapvoet; retrospectief onderzoek met follow-up bij 12 patiënten.

OBJECTIVE: To evaluate the results of transposition of the tendon of the M. tibialis posterior in patients with a drop foot. DESIGN: Descriptive, retrospective and follow-up investigation. METHODS: Surgical treatment was carried out in 12 patients with a drop foot (9 women and 3 men, with an average age of 37 years) in the period 1986-1998. The aetiology of the drop foot was a traumatic or iatrogenic lesion of the peroneal nerve or sciatic nerve in 9 patients and in 3 patients spina bifida occulta, leprosy and a herniation of a lumbar disc respectively. None of the patients had important comorbidity. Treatment consisted of lengthening the Achilles tendon according to Huckstep, transposition of the tibial posterior tendon in two tails to the dorsomedial and dorsolateral side of the foot, and six weeks of immobilisation in plaster of Paris. RESULTS: The postoperative period was without complications. The treatment improved the heel-toe steppage gait in all patients. None of the 10 patients who had used an orthosis preoperatively still used it at the time of the follow up. Fifty per cent of the patients acquired a dorsiflexion of the foot of more than 0 degree. The results were in accordance with those in the literature. CONCLUSION: Transposition of the tibial posterior tendon is a worthwhile alternative for those patients with a drop foot (and without important comorbidity) who cannot walk satisfactorily with an ankle-foot orthosis.

Hinge-helix formation and DNA bending in various lac repressor-operator complexes.

The hinge-region of the lac repressor plays an important role in the models for induction and DNA looping in the lac operon. When lac repressor is bound to a tight-binding symmetric operator, this region forms an alpha-helix that induces bending of the operator. The presence of the hinge-helices is questioned by previous data that suggest that the repressor does not bend the wild-type operator. We show that in the wild-type complex the hinge-helices are formed and the DNA is bent, similar to the symmetric complex. Furthermore, our data show differences in the binding of the DNA binding domains to the half-sites of the wild-type operator and reveal the role of the central base-pair of the wild-type operator in the repressor-operator interaction. The differences in binding to the operator half-sites are incorporated into a model that explains the relative affinities of the repressor for various lac operator sequences that contain left and right half-sites with different spacer lengths.

Closure of radial forearm free flap donor site with local full-thickness skin graft.

A triangular shaped full-thickness skin graft harvested adjacent to the donor site of the radial forearm flap, as originally described by Liang et al, has successfully been used in seven consecutive patients for coverage of the donor site of the radial forearm free flap. In all patients this resulted in a robust coverage with no late wound breakdown and an aesthetic appearance far superior to split-thickness skin-graft coverage. We recommend this technique which is feasible in the majority of cases and reduces both donor site and graft site morbidity of the radial forearm flap.

The solution structure of Lac repressor headpiece 62 complexed to a symmetrical lac operator.

BACKGROUND: Lactose repressor protein (Lac) controls the expression of the lactose metabolic genes in Escherichia coli by binding to an operator sequence in the promoter of the lac operon. Binding of inducer molecules to the Lac core domain induces changes in tertiary structure that are propagated to the DNA-binding domain through the connecting hinge region, thereby reducing the affinity for the operator. Protein-protein and protein-DNA interactions involving the hinge region play a crucial role in the allosteric changes occurring upon induction, but have not, as yet, been analyzed in atomic detail. RESULTS: We have used nuclear magnetic resonance (NMR) spectroscopy and restrained molecular dynamics (rMD) to determine the structure of the Lac repressor DNA-binding domain (headpeice 62; HP62) in complex with a symmetrized lac operator. Analysis of the structures reveals specific interactions between Lac repressor and DNA that were not found in previously investigated Lac repressor-DNA complexes. Important differences with the previously reported structures of the HP56-DNA complex were found in the loop following the helix-turn-helix (HTH) motif. The protein-protein and protein-DNA interactions involving the hinge region and the deformations in the DNA structure could be delineated in atomic detail. The structures were also used for comparison with the available crystallographic data on the Lac and Pur repressor-DNA complexes. CONCLUSIONS: The structures of the HP62-DNA complex provide the basis for a better understanding of the specific recognition in the Lac repressor-operator complex. In addition, the structural features of the hinge region provide detailed insight into the protein-protein and protein-DNA interactions responsible for the high affinity of the repressor for operator DNA.

Surface location and orientation of the lantibiotic nisin bound to membrane-mimicking micelles of dodecylphosphocholine and of sodium dodecylsulphate.

The interaction of nisin, a membrane-interacting cationic polypeptide, with membrane-mimicking micelles of zwitterionic dodecylphosphocholine and of anionic sodium dodecylsulphate was studied. Direct contacts have been established through the observation of NOEs between nisin and micelle protons. Spin-labeled DOXYL-stearic acids were incorporated into the two micellar systems. From the paramagnetic broadening effects induced in the 1H-NMR spectrum of nisin it is concluded that the molecule is localized at the surface of the micelles. The interactions of nisin with zwitterionic and with anionic micelles resemble each other as do the nisin conformations [van den Hooven, H. W., Doeland, C. C. M., van de Kamp, M., Konings, R. N. H., Hilbers, C. W. & van de Ven, F. J. M. (1995) Eur J. Biochem. 235, 382-393]. The hydrophobic residues are immersed into the micelles and oriented towards the center, whereas the more polar or charged residues have an outward orientation. The micellar systems are considered to model the first step in the mechanism of antimicrobial action of nisin, this step is the binding of nisin to the cytoplasmic membrane of target bacteria. Detailed information on this initial binding step is obtained. Hydrophobic and electrostatic interactions appear to be involved in the nisin-micelle contacts. It is suggested that subtilin, a lantibiotic structurally related to nisin, has a comparable membrane interaction surface.

Improved HSQC experiments for the observation of exchange broadened signals.

We present here HSQC experiments with improved sensitivity for signals in the presence of exchange broadening. During periods of coherence transfer through scalar coupling the experiments employ CPMG-derived pulse trains to reduce loss of dephasing of spin coherence due to chemical exchange. (15)N-(1)H gradient CPMG-HSQC and SE-CPMG-HSQC experiments have been developed and applied to complexes of lac repressor headpiece with operator DNA. Improved sensitivity is demonstrated for many protein backbone and side-chain resonances in the complex, markedly for signals of protons located at the protein-DNA interface. In addition, a significant increase in intensity is observed for arginine guanidino groups undergoing conformational exchange.

[Acral glomus tumors]. / Glomustumoren in de acra.

The glomus tumour is a rare condition occurring mainly in the fingers. The symptoms are characteristic: extreme tenderness together with cold intolerance, but the diagnosis is mostly delayed by many years, even decades. The relevant data of 20 patients with the tumour are presented. Extirpation of the tumour is the therapy of choice.