Choosing the correct Limberg flap.

A technique is presented for designing the 8 possible Limberg flaps to close any given rhomboidal defect. Then we show how to choose out of those 8 the only two that will be correctly oriented so the donor area of the Limberg flap can be closed with a minimal amount of tension.     

Geometric limit of multiple local Limberg flaps: a flap design.

The Limberg rhombic flap is a reliable and widely used technique in head and neck surgery. Since Limberg introduced his original design in 1946, several modifications of the technique have been described. Although a single Limberg flap is frequently used at the face to close small to medium defects, multi-Limberg flap techniques can help the surgeon to cover moderate to large defects of the extremities, trunk, and back. In this study, a design of four neighboring local Limberg flaps to cover a moderate to large defect without using a skin graft is introduced. It is believed that this design is the geometric limit of multiple Limberg flaps that can entirely cover a single large rhombic defect, because one Limberg flap unit can only be adjoined by three others, one from the tip and two from the sides. This flap design of four local Limberg flaps is also the only geometrically possible design that can keep all the bases of these four flaps free of incisions if one attempts to prepare four small Limberg flaps around a large rhombic defect.     

Gene transfer into isolated and cultured tobacco zygotes by a specially designed device for electroporation

 We have established a technique for isolating, culturing and transforming tobacco zygotes. Zygotes were isolated by microdissection or enzymatic maceration from fertilized embryo sacs. Viable zygotes cocultured with mesophyll protoplasts underwent first division after 3 days of culture. Zygotes isolated by microdissection underwent a higher frequency of first division (61.2%) than those isolated by enzymatic maceration (30.5%). Globular embryos were formed only from microdissected zygotes, at a frequency of 8.7% after 1–2 weeks in culture. An efficient millicell device for the electroporation of DNA into zygotes was established. The electroporated zygotes divided in vitro at a frequency of 54.6% and developed into proembryos. Introduced GFP gene constructs showed transient expression in about 2.6% of the electroporated tobacco zygotes. Received: 2 February 2000 / Revision received: 6 April 2000 / Accepted: 24 May 2000     

Cell size: chromosomes get slapped by a midzone ruler

Spatial and temporal coordination of mitotic events has been generally attributed to the coincidental outcome of increasing cyclin-dependent kinase activity. A recent study reports that mitotic events and structures previously considered to be independently controlled are capable of trans-regulation to ensure genomic integrity.     

A comparison of simple growth vessels and a specially designed bioreactor for the cultivation of hybridoma cells

Three tank type bioreactors of very simple design were compared to a commercially available laboratory-scale bioreactor, designed especially for mammalian cell culture, for their ability to support hybridoma growth and antibody production under batch culture conditions. The comparison reveals quite similar numbers for maximum viable cell densities and IgG production, despite large differences in vessel and agitator geometry and aeration mode. Furthermore, some data indicate that the hydrodynamic stress level in the growth vessels may influence the specific production rate of the cells and thus the overall productivity of the reactors.     

A molecularly imprinted catalyst designed by a computational approach in catalysing a transesterification process

A computational approach was developed to optimize the monomer formulation of molecularly imprinted catalysts. A virtual library of the intermediates of a lipase-catalysed transesterification process was constructed using Chem3D software with p-nitrophenyl acetate as substrate. The energies of the intermediates were minimized using the semi-empirical MOPAC method with the most stable intermediate expected to lead to a higher turn over rate. According to the optimization results, a MIC was prepared by co-polymerising 4(5)-vinylimidazole and itaconic acid with trimethylpropanol trimethacrylate micro spheres in the presence of p-nitrophenyl acetate. The MIC achieved of the transesterification process between p-nitrophenyl acetate and hexanol with a turn over rate of 26.2 min(-1), and showed substrate specificity towards its template with a 6.5-fold preference for p-nitrophenyl acetate over p-nitrophenyl salicylate.     

Gauging a hydrocarbon ruler by an intrinsic exciton probe

The structural basis of lipid acyl-chain selection by membrane-intrinsic enzymes is poorly understood because most integral membrane enzymes of lipid metabolism have proven refractory to structure determination; however, robust enzymes from the outer membranes of gram-negative bacteria are now providing a first glimpse at the underlying mechanisms. The methylene unit resolution of the phospholipid:lipid A palmitoyltransferase PagP is determined by the hydrocarbon ruler, a 16-carbon saturated acyl-chain-binding pocket buried within the transmembrane beta-barrel structure. Substitution of Gly88 lining the floor of the hydrocarbon ruler with Ala or Met makes the enzyme select specifically 15- or 12-carbon saturated acyl chains, respectively, indicating that hydrocarbon ruler depth determines acyl-chain selection. However, the Gly88Cys PagP resolution does not diminish linearly because it selects both 14- and 15-carbon saturated acyl chains. We discovered that an exciton, emanating from a buried Tyr26-Trp66 phenol-indole interaction, is extinguished by a local structural perturbation arising from the proximal Gly88Cys PagP sulfhydryl group. Site-specific S-methylation of the single Cys afforded Gly88Cys-S-methyl PagP, which reasserted both the exciton and methylene unit resolution by specifically selecting 13-carbon saturated acyl chains for transfer to lipid A. Unlike the other Gly88 substitutions, the Cys sulfhydryl group recedes from the hydrocarbon ruler floor and locally perturbs the subjacent Tyr26 and Trp66 aromatic rings. The resulting hydrocarbon ruler expansion thus occurs at the exciton's expense and accommodates an extra methylene unit in the selected acyl chain. The hydrocarbon ruler-exciton juxtaposition endows PagP with a molecular gauge for probing the structural basis of lipid acyl-chain selection in a membrane-intrinsic environment.     

The fasciocutaneous flap: a conservative approach to the exposed knee joint

The exposed knee joint poses a challenge to the reconstructive surgeon. The currently popular approach to the repair of exposed knee joints is use of muscle flaps. However, this leaves the patient with a deficit. We have therefore begun using the fasciocutaneous flap as an initial approach to this problem. In seven patients, aged 28 to 74 years, fasciocutaneous flaps have been the reconstructive procedure of choice for repair of exposed knee joints. One patient with a very large open wound required a concomitant medial gastrocnemius muscle flap. One minor wound separation occurred in a paraplegic patient with severe spasm. No other complications occurred. Follow-up ranged from 3 to 12 months, with good success in wound closure. An approach to small and intermediate wounds is presented in which the V-Y technique is used to obviate the need for skin grafting of the donor site.     

A new specially designed needle significantly increases sample yield during fine needle aspiration of breast lesions

A large and increasing number of women in the western world will at some point during their life be investigated morphologically for breast cancer. Fine needle aspiration (FNA) is one morphological method which is considered to be the fastest, cheapest and the most patient-friendly approach. Nevertheless, the technique has not gained major clinical success outside of Scandinavia, mainly because of a high frequency of insufficient samples. With this in mind it is quite peculiar that standard needles which are mainly configured for blood sampling and infusion therapy, comprising large quantities of residual spaces, are used. In this study we have developed and tested a new needle dedicated for FNA, which is intended to abate this drawback by increasing the sampling yield by changing the tip angle, the cannula wall-thickness and the storage compartment. In total, 499 consecutive aspiration procedures of palpable breast lesions were performed to compare the new needle (outer diameter 0.6 mm) with standard needles (outer diameters 0.6 mm and 0.7 mm). The new needle provided three times more material than did standard needles of the same diameter. Surprisingly, the new needle also provided more material than the standard 0.7 mm needle, which increased up to almost twice the material in cases with no material in the syringe. The frequency of tests with sparse harvested material (<4 mg) was less with the new needle (9%) compared to its standard counterpart (35%). The presented results were obtained by a very skilled sampling operator. Thus for the average sampling operator who probably obtains more samples in the spare range, the new dedicated FNA needle should have even more added value.     

Ramesh Gulati: a personal approach,based on his retirement lecture

Historical and modern migrations and dispersal of most marine organisms (intertidal, benthic, meiofaunal, planktonic, nektonic, or neustonic) are classically interpreted in terms of their natural dispersal potential. Exceptions are introduced species, largely recognized since the 19th century, known to have been transported by human activities. However, humans were transporting species along coastlines and across oceans for millennia and centuries prior to the advent of the first biological surveys. Thus, the presumptive natural distributions of many species may be questioned. Reviewed here are some basic concepts about invasions of non-native species. Human activities move species isolated in time and space from other oceans or continents, and thus human-mediated transport does not simply speed up natural dispersal processes. Both past and modern-day invasions are often overlooked, leading to an underestimation of the scale of invasion diversity and impact. Because vectors, donor regions, and recipient regions change over time, invasions will continue along long-standing but un-managed corridors. The impact of most invasions has never been studied and, therefore, it is not possible to conclude that most invasions have no impact, nor is it generally possible to say that invasions have become `integrated' into a community or ecosystem in ecological time. Finally, invasions in the ocean are not limited to harbours and ports, but are found in a wide variety of marine habitats, ranging from the open ocean continental shelf to exposed rocky shores. The existence of human-mediated vectors has created extraordinary challenges to our understanding and interpretation of the ecology, biogeography, evolutionary biology, and conservation biology of marine communities.     

Aesthetic abdominal deformities: a personal approach to the posterior rectus sheath and rectus muscles

We have detailed our experience with abdominoplasty. The technique is based on undermining of the rectus abdominis muscle, treatment of the posterior sheath, and limited resection of the medial edge of the rectus muscle. The fatty and muscular redundancy in the epigastric region has been eliminated by resection of the muscle edge or local suction lipectomy.