Reconstruction of large composite oromandibulomaxillary defects with free vertical rectus abdominis myocutaneous flaps

Large composite oromandibulomaxillary defects resulting from oncologic resection can be challenging to reconstruct with a single flap, and functional outcomes remain anecdotal. The purpose of this study was to evaluate the authors' surgical experience and scientifically analyze and describe the functional outcomes associated with the use of the vertical rectus abdominis myocutaneous flap for reconstruction of these defects. The records of seven patients (mean age, 62 years) who underwent composite resection including hemimandibulectomy, partial maxillectomy, partial pharyngectomy, and floor-of-mouth resection followed by immediate free vertical rectus abdominis myocutaneous flap reconstruction at The University of Texas M. D. Anderson Cancer Center (1998 to 2002) were retrospectively reviewed. The tumor type was squamous cell carcinoma in all seven cases; four patients had T4 primary lesions and three had local recurrences. Radiotherapy was used preoperatively in each of the three recurrent cases (mean dose, 70.6 Gy) and postoperatively in three of the four patients with primary tumors (mean dose, 63.0 Gy). The mean length of hospitalization was 8.7 days. There were no major flap complications, fistulas, or donor-site complications. Partial flap necrosis (4 percent of flap area) occurred in one patient and dehiscence of the neck incision occurred in another. Both cases were managed with surgical débridement and closure. A third patient developed a 0.75-cm superficial suture line abscess that healed with dressing changes. The mean postoperative follow-up was 15 months. Six of the seven patients remained tube dependent for their nutrition despite some swallowing improvement; one patient returned to full oral intake. The most common swallowing deficit was impaired laryngeal excursion, which occurred in all six patients evaluated with videofluoroscopic examination and resulted in risk for aspiration in patients and frank aspiration in 83 percent. Speech was intelligible on routine follow-up visits in all patients except one. Four patients died as a result of their cancer, one was alive with metastatic disease, and two were alive with no evidence of disease at last follow-up. The goal for patients undergoing extensive composite oromandibulomaxillary resection for advanced cancer is to restore structure, minimize postoperative morbidity, and optimize the quality of remaining life. Reconstruction with the free vertical rectus abdominis myocutaneous flap achieves early wound healing, allows timely delivery of adjuvant therapy, and can be accomplished with predictable success and minimal morbidity. To our knowledge, this study represents the first to scientifically analyze and quantify swallowing function following free vertical rectus abdominis myocutaneous flap reconstruction for large oromandibulomaxillary defects. Understanding of the specific physiologic swallowing deficits that typically occur after such reconstructions will provide clinicians with important surgical and reconstructive information to enable future improvements in functional success in a population for whom the prognosis is poor and treatment options are limited.     

Stochasticity, invasions, and branching random walks

We link deterministic integrodifference equations to stochastic, individual-based simulations by means of branching random walks. Using standard methods, we determine speeds of invasion for both average densities and furthest-forward individuals. For density-independent branching random walks, demographic stochasticity can produce extinction. Demographic stochasticity does not, however, reduce the overall asymptotic speed of invasion or preclude continually accelerating invasions.     

Ectoparasites of the swift fox in northwestern Texas

Ectoparasites were collected from chemically immobilized swift foxes (Vulpes velox) in the Texas Panhandle (USA). Three species of fleas (Pulex irritans, Dactylopsylla percernis, and Euhoplopsyllus affinis) and one species of tick (Ixodes sculptus) were found. Pulex irritans was the only abundant ectoparasite; it occurred on all 23 foxes brushed in 1999-2000 and all but one of 34 hosts examined in 2000-01. Otherwise, this swift fox population had a depauperate ectoparasite fauna; the remainder of the ectoparasites only occurred on a few (< or =5%) of the hosts. Because of previous taxonomic confusion between P. irritans and the closely related P. simulans, the zoogeographic distribution of these two species in many areas of western North America needs to be verified. Apparently, only the human flea P. irritans occurs on wild canids in the Texas Panhandle. However, there are previous records of P. simulans on other carnivores in western and central Texas. Some of these specimens were reexamined, and their identifications were reconfirmed. Also, the recent literature on the controversial taxonomic status of these two flea species is reviewed. The male terminal aedeagal sexual apparatus is the only means currently available to separate P. irritans and P. simulans.     

Measurement of biologically available naphthalene in gas and aqueous phases by use of a Pseudomonas putida biosensor

Genetically constructed microbial biosensors for measuring organic pollutants are mostly applied in aqueous samples. Unfortunately, the detection limit of most biosensors is insufficient to detect pollutants at low but environmentally relevant concentrations. However, organic pollutants with low levels of water solubility often have significant gas-water partitioning coefficients, which in principle makes it possible to measure such compounds in the gas rather than the aqueous phase. Here we describe the first use of a microbial biosensor for measuring organic pollutants directly in the gas phase. For this purpose, we reconstructed a bioluminescent Pseudomonas putida naphthalene biosensor strain to carry the NAH7 plasmid and a chromosomally inserted gene fusion between the sal promoter and the luxAB genes. Specific calibration studies were performed with suspended and filter-immobilized biosensor cells, in aqueous solution and in the gas phase. Gas phase measurements with filter-immobilized biosensor cells in closed flasks, with a naphthalene-contaminated aqueous phase, showed that the biosensor cells can measure naphthalene effectively. The biosensor cells on the filter responded with increasing light output proportional to the naphthalene concentration added to the water phase, even though only a small proportion of the naphthalene was present in the gas phase. In fact, the biosensor cells could concentrate a larger proportion of naphthalene through the gas phase than in the aqueous suspension, probably due to faster transport of naphthalene to the cells in the gas phase. This led to a 10-fold lower detectable aqueous naphthalene concentration (50 nM instead of 0.5 micro M). Thus, the use of bacterial biosensors for measuring organic pollutants in the gas phase is a valid method for increasing the sensitivity of these valuable biological devices.     

Enhanced arsenic accumulation in engineered bacterial cells expressing ArsR

The metalloregulatory protein ArsR, which offers high affinity and selectivity toward arsenite, was overexpressed in Escherichia coli in an attempt to increase the bioaccumulation of arsenic. Overproduction of ArsR resulted in elevated levels of arsenite bioaccumulation but also a severe reduction in cell growth. Incorporation of an elastin-like polypeptide as the fusion partner to ArsR (ELP153AR) improved cell growth by twofold without compromising the ability to accumulate arsenite. Resting cells overexpressing ELP153AR accumulated 5- and 60-fold-higher levels of arsenate and arsenite than control cells without ArsR overexpression. Conversely, no significant improvement in Cd(2+) or Zn(2+) accumulation was observed, validating the specificity of ArsR. The high affinity of ArsR allowed 100% removal of 50 ppb of arsenite from contaminated water with these engineered cells, providing a technology useful to comply with the newly approved U.S. Environmental Protection Agency limit of 10 ppb. These results open up the possibility of using cells overexpressing ArsR as an inexpensive, high-affinity ligand for arsenic removal from contaminated drinking and ground water.     

Heat shock protein-mediated resistance to high hydrostatic pressure in Escherichia coli

A random library of Escherichia coli MG1655 genomic fragments fused to a promoterless green fluorescent protein (GFP) gene was constructed and screened by differential fluorescence induction for promoters that are induced after exposure to a sublethal high hydrostatic pressure stress. This screening yielded three promoters of genes belonging to the heat shock regulon (dnaK, lon, clpPX), suggesting a role for heat shock proteins in protection against, and/or repair of, damage caused by high pressure. Several further observations provide additional support for this hypothesis: (i). the expression of rpoH, encoding the heat shock-specific sigma factor sigma(32), was also induced by high pressure; (ii). heat shock rendered E. coli significantly more resistant to subsequent high-pressure inactivation, and this heat shock-induced pressure resistance followed the same time course as the induction of heat shock genes; (iii). basal expression levels of GFP from heat shock promoters, and expression of several heat shock proteins as determined by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins extracted from pulse-labeled cells, was increased in three previously isolated pressure-resistant mutants of E. coli compared to wild-type levels.     

Synergistic anion-directed coordination of ferric and cupric ions to bovine serum transferrin--an inorganic perspective

A series of new iron(III) and copper(II) complexes of bovine serum transferrin (BTf), with carbonate and/or oxalate as the synergistic anion, are presented. The complexes [Fe(2)(CO(3))(2)BTf], [Fe(2)(C(2)O(4))(2)BTf], [Cu(2)(CO(3))(2)BTf] and [Cu(C(2)O(4))BTf] were prepared by standard titrimetric techniques. The oxalate derivatives were also obtained from the corresponding carbonate complexes by anion-displacement. The site-preference of the transition metal-oxalate synergism has facilitated the preparation and isolation of the mononuclear complex [Cu(C(2)O(4))BTf], the mixed-anion complexes [Cu(2)(CO(3))(C(2)O(4))BTf] and [Fe(2)(CO(3))(C(2)O(4))BTf] and the mixed-metal complex [FeCu(C(2)O(4))(2)BTf]. The sensitivity of electron paramagnetic resonance (EPR) spectroscopy to the nature of the synergistic anions at the specific-binding sites of the transferrins has made this physical technique particularly indispensable to this study. None of the other members of the transferrin family of proteins has ever been demonstrated to bind the ferric and cupric ions one after the other, each occupying a separate specific-binding site of the same transferrin molecule, as a response to the coordination restrictions imposed by the oxalate ion. The bathochromic shift of the visible p(pi)-d(pi*) CT band for iron(III)-BTf and the hypsochromic shift of the p(pi)-d(sigma*) CT band for copper(II)-BTf, on replacing carbonate by oxalate as the associated anion, are consistent with the relative positions of these anionic ligands in the spectrochemical series and the nature of the d-type acceptor orbitals involved in the CT transitions. The binding and spectroscopic properties of bovine serum transferrin--a serum transferrin--very nearly mirror those of human serum transferrin, but differ significantly from those of human lactoferrin.     

The law and the local fairness of care practice. Reflections on the ethnographic field investigation concerning the failure of the Bopz Act in psychogeriatric nursing home care

Ten years after its introduction the Special Admissions to Psychiatric Hospitals Act (Bopz) still awaits full implementation in the field of psychogeriatric nursing home care. Ethnographic research into moral problems related to care giving in dementia patients in Dutch nursing homes yielded several reasons for this discrepancy between law and care practice. Firstly, practical effectuation of this law rests predominantly on the shoulders of nurses and nurse assistants who are mainly inspired by moral motives such as carefulness and providing safety and who are ill informed about the law and its prerequisites. Secondly, there is the problem of the loss of a common shared world of meaning, which in relational terms is typical for the process of dementia. As a result of this, crucial concepts of the Bopz loose their applicability as the disease progresses. Finally, there is an immanent tension between the anthropology of care and care giving and the anthropological presuppositions of the law, health law included, which on a fundamental level contributes to the resistance of the care practice to the legal procedures of the Bopz. These factors must be accounted for in new legislation or revision of the current law. In the mean time we urge the necessity to develop a moral code concerning how to deal with resistive behaviour and opposition to care of demented nursing home patients.