Sustained secretion of human alpha-1-antitrypsin from murine muscle transduced with adeno-associated virus vectors

Recombinant adeno-associated virus (AAV) vectors have been used to transduce murine skeletal muscle as a platform for secretion of therapeutic proteins. The utility of this approach for treating alpha-1-antitrypsin (AAT) deficiency was tested in murine myocytes in vitro and in vivo. AAV vectors expressing the human AAT gene from either the cytomegalovirus (CMV) promoter (AAV-C-AT) or the human elongation factor 1-alpha promoter (AAV-E-AT) were examined. In vitro in C2C12 murine myoblasts, the expression levels in transient transfections were similar between the two vectors. One month after transduction, however, the human elongation factor 1 promoter mediated 10-fold higher stable human AAT expression than the CMV promoter. In vivo transduction was performed by injecting doses of up to 1.4 x 10(13) particles into skeletal muscles of several mouse strains (C57BL/6, BALB/c, and SCID). In vivo, the CMV vector mediated higher levels of expression, with sustained serum levels over 800 micrograms/ml in SCID and over 400 micrograms/ml in C57BL/6 mice. These serum concentrations are 100,000-fold higher than those previously observed with AAV vectors in muscle and are at levels which would be therapeutic if achieved in humans. High level expression was delayed for several weeks but was sustained for over 15 wk. Immune responses were dependent upon the mouse strain and the vector dosage. These data suggest that recombinant AAV vector transduction of skeletal muscle could provide a means for replacing AAT or other essential serum proteins but that immune responses may be elicited under certain conditions.

The transcriptional repressor CDP (Cutl1) is essential for epithelial cell differentiation of the lung and the hair follicle

The mammalian Cutl1 gene codes for the CCAAT displacement protein (CDP), which has been implicated as a transcriptional repressor in diverse processes such as terminal differentiation, cell cycle progression, and the control of nuclear matrix attachment regions. To investigate the in vivo function of Cutl1, we have replaced the C-terminal Cut repeat 3 and homeodomain exons with an in-frame lacZ gene by targeted mutagenesis in the mouse. The CDP-lacZ fusion protein is retained in the cytoplasm and fails to repress gene transcription, indicating that the Cutl1(lacZ) allele corresponds to a null mutation. Cutl1 mutant mice on inbred genetic backgrounds are born at Mendelian frequency, but die shortly after birth because of retarded differentiation of the lung epithelia, which indicates an essential role of CDP in lung maturation. A less pronounced delay in lung development allows Cutl1 mutant mice on an outbred background to survive beyond birth. These mice are growth-retarded and develop an abnormal pelage because of disrupted hair follicle morphogenesis. The inner root sheath (IRS) is reduced, and the transcription of Sonic hedgehog and IRS-specific genes is deregulated in Cutl1 mutant hair follicles, consistent with the specific expression of Cutl1 in the progenitors and cell lineages of the IRS. These data implicate CDP in cell-lineage specification during hair follicle morphogenesis, which resembles the role of the related Cut protein in specifying cell fates during Drosophila development.

Gasless laparoscopy may reduce the risk of port-site metastases following laparascopic tumor surgery

OBJECTIVE

To compare the incidence of port-site metastases in an experimental tumor model following tumor manipulation during laparoscopy aided by conventional insufflation with laparoscopy using a gasless technique.

SETTING

An experimental model applied in a research laboratory.

PARTICIPANTS AND INTERVENTIONS

Malignant tumors were implanted in the abdominal wall of 24 rats. Twelve rats underwent tumor laceration at laparoscopy with carbon dioxide insufflation, and 12 rats underwent the same procedure during gasless laparoscopy achieved by abdominal wall suspension. Rats were killed 1 week later and were examined for evidence of tumor metastases. The surgical wounds were examined microscopically by a histopathologist who was unaware of the operative technique used and the site of origin of the specimens.

MAIN OUTCOME MEASURE

Histologically confirmed tumor metastasis to laparoscopic port wounds.

RESULTS

Growth of the primary tumor was equal in both groups. Wound metastases were less likely in the gasless laparoscopy group (3 of 12 vs 10 of 12; P = .01, Fisher exact test).

CONCLUSION

The use of laparoscopy without gas insufflation may reduce the risk of wound metastasis following laparoscopic surgery for cancer.

Wound metastases following laparoscopic and open surgery for abdominal cancer in a rat model

The recent application of laparoscopic resection techniques to malignant disease has raised safety concerns due to metastasis to surgical access wounds. The significance and incidence of this problem are controversial. In the present study a rat model, in which an implanted tumour was lacerated, was used to investigate whether application of laparoscopic techniques for malignant abdominal disease leads to an increased risk of tumour dissemination and implantation within the peritoneal cavity, and abdominal wall wounds. Malignant cells were implanted into the abdominal wall of 42 rats, resulting 7 days later in the growth of a tumour measuring 20-25 mm in diameter. There were three control groups: no surgery (n = 6); blunt manipulation of the tumour laparoscopically (n = 6); and blunt manipulation of the tumour at laparotomy (n = 6). Twenty-four rats underwent surgical laceration of the tumour capsule at either laparoscopy (n = 12) or laparotomy (n = 12). All rats were killed 1 week later, and examined for macroscopic evidence of tumour metastasis. The abdominal surgical wounds were excised for independent microscopic examination by a histopathologist. Growth of the primary tumour was greater in rats that had an operation than in unoperated controls, and was greater after laparotomy. However, wound metastases were five times more likely after laparoscopic tumour laceration than after the same procedure through an open incision (ten of 12 rats versus two of 12, P = 0.0033). Wound metastases following laparoscopic tumour manipulation are an important and real problem, with significant implications for the application of laparoscopic techniques to excise malignant disease in humans.

Which measures of physical function and motor impairment best predict quality of life in Parkinson's disease?

INTRODUCTION

Our objective was to compare the relative value of elements of the motor system in predicting the physical mobility domain of health related quality of life in patients with Parkinson's disease in order to specify targets for intervention.

METHODS

In this cross-sectional study, the Parkinson's disease questionnaire-39 was administered to 263 subjects with Parkinson's disease to assess health related quality of life. Demographics, motor impairments and physical function were assessed using the Unified Parkinson disease rating scale, 10-m walk test, 6-min walk test, Freezing of gait questionnaire, Timed up & go, functional gait assessment, Berg balance test, functional reach and 9-hole peg test.

RESULTS

The results revealed that demographic factors accounted for 19.7% of the variance in Parkinson disease questionnaire-39 mobility score. When motor impairments were added to the model, the bradykinesia composite score contributed a significant portion of the variance (R(2) change = 0.12, p < 0.001). The tremor and rigidity composite scores did not contribute significantly. The Freezing of gait questionnaire was the strongest predictor (R(2) change = 0.23, p < 0.001) of the physical function tests followed by Functional gait assessment (R(2) change = 0.06, p < 0.001) and 6-min walk test (R(2) change = 0.01, p = 0.01). Collectively, 61% of the variance in Parkinson disease questionnaire-39 mobility score and 41.5% of the Parkinson disease questionnaire-39(total) score was accounted for.

DISCUSSION

These results suggest greater value of physical function tests, and not tests of motor impairments, in predicting health related quality of life.

Rapid host strain improvement by in vivo rearrangement of a synthetic yeast chromosome

Synthetic biology tools, such as modular parts and combinatorial DNA assembly, are routinely used to optimise the productivity of heterologous metabolic pathways for biosynthesis or substrate utilisation, yet it is well established that host strain background is just as important for determining productivity. Here we report that in vivo combinatorial genomic rearrangement of Saccharomyces cerevisiae yeast with a synthetic chromosome V can rapidly generate new, improved host strains with genetic backgrounds favourable to diverse heterologous pathways, including those for violacein and penicillin biosynthesis and for xylose utilisation. We show how the modular rearrangement of synthetic chromosomes by SCRaMbLE can be easily determined using long-read nanopore sequencing and we explore experimental conditions that optimise diversification and screening. This synthetic genome approach to metabolic engineering provides productivity improvements in a fast, simple and accessible way, making it a valuable addition to existing strain improvement techniques.

The Sc2.0 project has built the Synthetic Chromosome Rearrangement and Modification by LoxP-mediated Evolution (SCRaMbLE) system into their synthetic chromosomes. Here the authors use SCRaMbLE to rapidly develop, diversify and screen strains for diverse production and growth characteristics.

The impact of a monthly rest day on avian influenza virus isolation rates in retail live poultry markets in Hong Kong

Retail live poultry markets (LPMs) may act as a reservoir of avian influenza viruses (AIV). In this study we test the hypothesis that a rest day in the LPMs where the stalls are completely emptied of poultry, cleansed, and restocked will reduce the isolation rates of avian influenza viruses. The isolation rate of H9N2 subtype viruses from chicken was significantly lower after the rest day than prior to it, indicating its impact in reducing transmission. In contrast, Newcastle disease virus (NDV) isolation rates appear unaffected by this intervention, possibly reflecting differences in herd immunity or virus transmission dynamics.

Evaluation of four DNA typing techniques in epidemiological investigations of bovine tuberculosis

DNA fingerprinting techniques were used to type 273 isolates of Mycobacterium bovis from Australia, Canada, the Republic of Ireland, and Iran. The results of restriction fragment length polymorphism (RFLP) analysis with DNA probes from IS6110, the direct repeat (DR), and the polymorphic GC-rich sequence (PGRS) were compared with those of a new PCR-based method called spacer oligonucleotide typing (spoligotyping) developed for the rapid typing of Mycobacterium tuberculosis (J. Kamerbeek et al., J. Clin. Microbiol. 35:907-914, 1997). Eighty-five percent of the isolates harbored a single copy of IS6110, and 81.5% of these carried IS6110 on the characteristic 1.9-kb restriction fragment. RFLP analysis with IS6110 identified 23 different types, RFLP analysis with the DR probe identified 35 types, RFLP analysis with the PGRS probe identified 77 types, and the spoligotyping method identified 35 types. By combining all results, 99 different strains could be identified. Isolate clusters were frequently associated within herds or were found between herds when epidemiological evidence confirmed animal movements. RFLP analysis with IS6110 was sufficiently sensitive for the typing of isolates with more than three copies of IS6110, but RFLP analysis with the PGRS probe was the most sensitive typing technique for strains with only a single copy of IS6110. Spoligotyping may have advantages for the rapid typing of M. bovis, but it needs to be made more sensitive.

Clozapine and risperidone treatment of psychosis in Parkinson's disease

The authors compared efficacy and safety of risperidone and clozapine for the treatment of psychosis in a double-blind trial with 10 subjects with Parkinson's disease (PD) and psychosis. Mean improvement in the Brief Psychiatric Rating Scale psychosis score was similar in the clozapine and the risperidone groups (P=0.23). Although the mean motor Unified Parkinson's Disease Rating Scale score worsened in the risperidone group and improved in the clozapine group, this difference did not reach statistical significance. One subject on clozapine developed neutropenia. In subjects with PD, risperidone may be considered as an alternative to clozapine because it is as effective for the treatment of psychoses without the hematologic, antimuscarinic, and seizure side effects. However, risperidone may worsen extrapyramidal symptoms more than clozapine and therefore must be used with caution.

Discarded Human Thymus Is a Novel Source of Stable and Long-Lived Therapeutic Regulatory T Cells

Regulatory T cell (Treg)-based therapy is a promising approach to treat many immune-mediated disorders such as autoimmune diseases, organ transplant rejection, and graft-versus-host disease (GVHD). Challenges to successful clinical implementation of adoptive Treg therapy include difficulties isolating homogeneous cell populations and developing expansion protocols that result in adequate numbers of cells that remain stable, even under inflammatory conditions. We investigated the potential of discarded human thymuses, routinely removed during pediatric cardiac surgery, to be used as a novel source of therapeutic Tregs. Here, we show that large numbers of FOXP3(+) Tregs can be isolated and expanded from a single thymus. Expanded thymic Tregs had stable FOXP3 expression and long telomeres, and suppressed proliferation and cytokine production of activated allogeneic T cells in vitro. Moreover, expanded thymic Tregs delayed development of xenogeneic GVHD in vivo more effectively than expanded Tregs isolated based on CD25 expression from peripheral blood. Importantly, in contrast to expanded blood Tregs, expanded thymic Tregs remained stable under inflammatory conditions. Our results demonstrate that discarded pediatric thymuses are an excellent source of therapeutic Tregs, having the potential to overcome limitations currently hindering the use of Tregs derived from peripheral or cord blood.

Stability boundaries and lateral postural control in parkinson's disease

Postural instability is a major problem in patients with Parkinson's disease (PD). We examined balance control in PD by using center of pressure (CP) variability and time-to-contact to investigate boundary relevant postural control behavior under quiet stance leaning conditions. Postural orientation was manipulated by having patients (n = 10) and healthy older controls (n = 7) lean forward and backward with varying degrees of lean on a force platform. The subjects were instructed to lean forward or backward (either halfway or as far as possible) without bending their hips or lifting their heels or toes off the ground. Time-to-contact of the CP with the geometric stability boundary defined by the feet as well as CP position and variability were analyzed. Medio-lateral CP variability was increased in the patients with PD. Medio-lateral average time-to-contact was decreased in the patients but not so in the anterior-posterior direction. In contrast to the CP variability, the medio-lateral variability of time-to-contact was lower in the patients. Patients as well as healthy older controls responded to lean manipulations with an increase in CP variability. Boundary relevant CP measures thus show clear changes in control strategies and confirm the role of lateral instability in PD.

The effect of laparoscopy on the movement of tumor cells and metastasis to surgical wounds

BACKGROUND

A variety of mechanisms have been proposed to explain tumor growth in port sites following laparoscopic cancer surgery. We devised two experimental models to determine whether carbon dioxide (CO2) insufflation during laparoscopic surgery influences the movement of tumor cells and leads to tumor implantation and growth in surgical wounds.

METHODS

Model 1: Viable adenocarcinoma cells were introduced into the upper abdomen of six syngeneic immune-competent rats during laparoscopy with CO2 insufflation; the same procedure was followed for a further six rats during gasless laparoscopy. A length of plastic tubing introduced through the anterolateral aspect of the rats' left lower abdominal wall was used to vent the insufflation gas through the abdomen of a recipient rat for 30 min. After 21 days, the peritoneal cavity and surgical wounds of the recipient rat were examined for implanted tumor. Model 2: A suspension of radiolabeled adenocarcinoma cells was introduced into the upper abdomen of five rats during laparoscopy with CO2 insufflation and an additional five rats during gasless laparoscopy. A length of plastic tubing introduced through the anterolateral aspect of the left lower abdominal flank was used to vent the insufflation gas through phosphate-buffered saline solution. After 30 min, the solution was counted for radioactivity.

RESULTS

Tumor growth occurred at the site of both the insufflation and venting ports in the second rat in five of the six rats from the group undergoing insufflation, but it was found in none of the gasless laparoscopy group (p = 0.015). In the second model, significant transfer of tumor cells to the vented gas occurred only in the rats undergoing laparoscopy with insufflation (median, 2.71% versus 0% of the introduced labeled cells; p = 0.008).

CONCLUSIONS

Carbon dioxide insufflation results in tumor dissemination during laparoscopy, leading to port site metastasis. Gasless laparoscopy may prevent this problem.

Tumor implantation following laparoscopy using different insufflation gases

BACKGROUND

Laparoscopic manipulation of malignancies is associated with an increased incidence of metastasis to port sites in experimental models. This study investigated the effect of different insufflation gases on the implantation of a tumor cell suspension following laparoscopic surgery in an established small animal model.

METHODS

Forty Dark Agouti rats underwent laparoscopy and the introduction into the peritoneal cavity of a tumor cell suspension. The insufflating gas used for each procedure was one of the following gases (10 rats in each group): carbon dioxide (CO2), nitrous oxide (N2O), helium, and air. The rats were killed 7 days after surgery, and the peritoneal cavity and port sites were examined for the presence of tumor.

RESULTS

Although no significant differences were seen between air, CO2, and N2O insufflation groups, tumor involvement of peritoneal surfaces was less likely following helium insufflation.

CONCLUSION

The results of this study suggest that tumor metastasis to port sites following laparoscopic surgery may be influenced by the choice of insufflation gas. In this study, helium was associated with reduced tumor growth.

Adverse impact of pneumoperitoneum on intraperitoneal implantation and growth of tumour cell suspension in an experimental model

BACKGROUND

An investigation of the effect of laparoscopy and CO2 pneumoperitoneum on the pattern of tumour implantation and growth in the peritoneal cavity was carried out.

METHODS

A suspension of viable adenocarcinoma cells was introduced into the left upper quadrant of the peritoneal cavity of 36 syngeneic immune-competent rats at laparotomy, laparoscopy with CO2 insufflation, and gasless laparoscopy (12 rats in each group). Six days later the peritoneal cavity and surgical wounds were examined for macroscopic evidence of implanted tumour. The abdominal cavity was divided into sectors and macroscopic tumour implantation was determined for each sector and wound. This was confirmed by histological examination.

RESULTS

While tumour implantation occurred in the vicinity of the tumour suspension introduction site in the laparotomy and gasless laparoscopy groups, implantation occurred throughout the peritoneal cavity, including areas remote to the introduction site, in the laparoscopy with CO2 insufflation group. Tumour growth was more likely in the port wounds of rats undergoing laparoscopy with insufflation than without.

CONCLUSIONS

In this model, CO2 insufflation during laparoscopy resulted in widespread tumour dissemination and implantation, when compared to laparotomy and gasless laparoscopy, supporting the postulate that wound metastasis and tumour spread may be more likely following laparoscopic cancer surgery in humans when CO2 insufflation is used.

The acetabular blood supply: implications for periacetabular osteotomies

As the popularity of juxta-acetabular osteotomies in adults increases, concern arises that such a procedure will potentially cause avascular necrosis of the acetabular fragment. In order to verify the remaining vascularization after a Bernese periacetabular osteotomy, an injection study with colored latex was performed. The vascularity of the outside of the periacetabular bone was studied in 16 hips after injection of colored latex into the abdominal aorta and the inside in four hips. To confirm the conclusions drawn from the anatomic study, a Bernese periacetabular osteotomy was performed in two additional hips after latex injection. This study demonstrated that through a modified Smith-Peterson approach and with execution of the osteotomies from the inside of the pelvis the acetabular fragment remains vascularized by the supra-acetabular and acetabular branches of the superior gluteal artery, the obturator artery and the inferior gluteal artery. Some uncertainty remains about how much correction is tolerated by the smaller blood vessels.

Efficient ex vivo transduction of pancreatic islet cells with recombinant adeno-associated virus vectors

The ability to transfer immunoregulatory, cytoprotective, or antiapoptotic genes into pancreatic islet cells may allow enhanced posttransplantation survival of islet allografts and inhibition of recurrent autoimmune destruction of these cells in type 1 diabetes. However, transient transgene expression and the tendency to induce host inflammatory responses have limited previous gene delivery studies using viral transfer vectors. We demonstrate here that recombinant adeno-associated virus (rAAV) serotype 2, a vector that can overcome these limitations, effectively transduces both human and murine pancreatic islet cells with reporter genes as well as potentially important immunoregulatory cytokine genes (interleukin-4, interleukin-10), although a very high multiplicity of infection (10,000 infectious units/islet equivalent) was required. This requirement was alleviated by switching to rAAV serotype 5, which efficiently transduced islets at a multiplicity of infection of 100. Although adenovirus (Ad) coinfection was required for efficient ex vivo expression at early time points, islets transduced without Ad expressed efficiently when they were transplanted under the renal capsule and allowed to survive in vivo. The rAAV-delivered transgenes did not interfere with islet cell insulin production and were expressed in both beta- and non-beta-cells. We believe rAAV will provide a useful tool to deliver therapeutic genes for modulating immune responses against islet cells and markedly enhance longterm graft survival.

Wound metastasis after laparoscopy with different insufflation gases

BACKGROUND

There is growing evidence that laparoscopy for malignancy is associated with an increased incidence of metastasis to port sites. This study investigated the effect of different insufflation gases on port-site metastasis after laparoscopy in an established animal model.

METHODS

Forty-eight Dark Agouti rats with an established adenocarcinoma in the left flank underwent laparoscopic intraperitoneal tumor laceration. The gas used for insufflation was one of the following (12 rats in each group): (1) CO2, (2) N2O, (3) helium, or (4) air. Rats were killed 7 days after the procedure, and the port sites were examined for the presence of tumor metastasis.

RESULTS

Tumor involvement of port sites was significantly less likely after helium insufflation than in the other groups (p < 0.0001). There was no significant difference between the air, CO2, and N2O groups.

CONCLUSIONS

This study suggests that the development of metastases in port sites after laparoscopy may be influenced in part by the choice of insufflation gas used to create the pneumoperitoneum. In particular, helium was associated with a reduced rate of metastases.

Clinical experience with sotalol in patients with drug-refractory ventricular arrhythmias

Sixty-five patients with symptomatic, drug-refractory, sustained ventricular tachycardia or fibrillation were treated with oral sotalol (80 to 480 mg twice daily). Sotalol was withdrawn in 11 patients because of continued inducibility of ventricular tachycardia at the time of follow-up electrophysiologic study. Therefore, the clinical effectiveness of sotalol could be evaluated in 54 patients followed up for 11.5 +/- 6 months (range 0.2 to 25). The actuarial incidence of successful sotalol therapy was 54 +/- 13% at 6 months and 47 +/- 13% at 12 months. In 39 patients who underwent electrophysiologic testing while receiving oral sotalol, the drug prevented the reinduction of ventricular tachycardia/fibrillation in 8 (20%). During follow-up study, arrhythmia recurred in 1 (17%) of 6 patients whose ventricular tachycardia was noninducible with oral sotalol and in 8 (44%) of 18 with inducible tachycardia but who were continued on oral sotalol therapy. Adverse effects were noted in 28 patients (42%), requiring drug withdrawal in 13 (22%) and dose reduction after hospital discharge in 10 (15%). Exacerbation of ventricular arrhythmia occurred in six patients (9%), one of whom had associated hypokalemia. Sotalol is frequently useful in the control of intractable, life-threatening ventricular arrhythmias, and its efficacy appears to be predicted by programmed stimulation. However, there is a high rate of limiting side effects, which precludes its use in a large number of patients, and a substantial risk of arrhythmia exacerbation.

Long-term effects of oppositional child treatment with mothers as therapists and therapist trainers

The follow-up data reported represent a long-term (3 to 9 years out of treatment) evaluation of 40 children who were clients of the Regional Intervention Program (RIP) from 1969 to 1978. As 3-, 4-, and 5-year olds, these youngsters exhibited severe and prolonged tantrums, continual opposition to adults' requests and commands, and physical aggression toward parents. Each child and mother participated in a standardized intervention package modeled after Wahler's Opposition Child Treatment. Results from school and home-based follow-up showed that: (a) commands, demands, or requests made by parents were likely to be followed by former clients' compliance; (b) former clients' social interactions in the homes were overwhelmingly positive and their nonsocial behavior was by and large appropriate; (c) parent behavior in the home was consistent with the child management skills taught many years ago; (d) there were no differences between the compliant, on-task, social interaction and appropriate/inappropriate nonsocial behaviors of former clients and randomly selected class peers; (e) there were no differences in teachers' commands, negative feedback, positive social reinforcement, and repeated commands that were directed toward either former clients or randomly selected class peers; (f) both teachers' and parents' rating of former clients on the modified Walker Problem Behavior Checklist were highly correlated; (g) there were no differences in teachers' rating of former clients and class peers; and (h) of all the studied demographic variables, only age that treatment began and family intactness were related to current levels of behavior.

Improved betulinic acid biosynthesis using synthetic yeast chromosome recombination and semi-automated rapid LC-MS screening

Synthetic biology, genome engineering and directed evolution offer innumerable tools to expedite engineering of strains for optimising biosynthetic pathways. One of the most radical is SCRaMbLE, a system of inducible in vivo deletion and rearrangement of synthetic yeast chromosomes, diversifying the genotype of millions of Saccharomyces cerevisiae cells in hours. SCRaMbLE can yield strains with improved biosynthetic phenotypes but is limited by screening capabilities. To address this bottleneck, we combine automated sample preparation, an ultra-fast 84-second LC-MS method, and barcoded nanopore sequencing to rapidly isolate and characterise the best performing strains. Here, we use SCRaMbLE to optimise yeast strains engineered to produce the triterpenoid betulinic acid. Our semi-automated workflow screens 1,000 colonies, identifying and sequencing 12 strains with between 2- to 7-fold improvement in betulinic acid titre. The broad applicability of this workflow to rapidly isolate improved strains from a variant library makes this a valuable tool for biotechnology.

Screw position affects dynamic compression plate strain in an in vitro fracture model

OBJECTIVE

This investigation considers the effect of a variety of screw positions on plate strain in three fracture models.

DESIGN

Dynamic compression plate fixation of in vitro fracture models.

METHODS

To model a fracture, a plastic pipe was cut transversely and a twenty-hole dynamic compression plate was attached by screws. Eighteen stacked, rectangular, rosette strain gauges were installed on the plate to evaluate strain. Three models were evaluated: two constructs in which there was no contact between the cut ends of the pipe under the fixation plate (small-and large-gap models) and a construct in which there was direct apposition of the cut ends (no-gap model). The pattern and magnitude of strains were assessed as a function of varying combinations of screw position for each model.

RESULTS

Maximal plate strain in the gap models was lowest with screws placed closest to the gap, compared with screws placed away from the gap or spaced apart. The no-gap model showed significantly lower strains when screws were placed further from the osteotomy site than when screws were positioned close together or spaced apart. In all cases, maximal plate strain occurred adjacent to the most central screw holes and rapidly dissipated along the length of the plate.

CONCLUSION

In a model simulating a comminuted fracture (gap), this study found that screws should be placed as close to the fracture site as possible to minimize plate strain. In an anatomically reduced two-part fracture model (no gap), widely spaced screws or those placed away from the fracture resulted in lower strains.

Radial forearm osteocutaneous free flap in maxillofacial and oromandibular reconstructions

OBJECTIVES/HYPOTHESIS

The radial forearm osteocutaneous free flap is an excellent reconstructive modality for oromandibular and maxillofacial reconstruction in certain well-defined circumstances. The initial concern over donor site morbidity and the ability of the bone to reconstruct mandibular defects have led to only a few published series.

STUDY DESIGN

Retrospective study of the experience of two tertiary medical centers with radial forearm osteocutaneous free flap.

METHODS

Retrospectively, 52 patients were studied who underwent radial forearm osteocutaneous free flap reconstruction for cancer (49 cases) and trauma (3 cases). Bone length and skin paddle harvested, general morbidity (hematoma, wound infection, and dehiscence), recipient site morbidity (nonunion of neomandible, flap failure, and bone or plate exposure), and donor site morbidity (radius bone fracture, plate exposure, and skin graft failure) were reviewed.

RESULTS

The average skin paddle size was 55.1 cm (range, 15-112 cm). The average radius bone harvest length was 6.3 cm (range, 2.5-11 cm). Donor site complications included tendon exposure (3 cases), radius bone fracture (1 case), and exposure of the plate (0). Recipient site complications included nonunion of the mandible (4), exposed mandible (1), exposed mandibular plates (2), exposed maxillary plates or bone (0), venous compromise (1), and flap failure (1). Two patients had perioperative deaths.

CONCLUSION

Radial forearm osteocutaneous free flap is a valuable and viable option for oromandibular and maxillofacial reconstruction.

Metabolic and immunologic consequences of laparoscopy with helium or carbon dioxide insufflation: a randomized clinical study

BACKGROUND

Previous studies using animal models have demonstrated that carbon dioxide (CO2) pneumoperitoneum during laparoscopy is associated with adverse physiological, metabolic, immunological and oncological effects, and many of these problems can be avoided by the use of helium insufflation. The present study was performed in patients to compare the effect of helium and CO2 insufflation on intraperitoneal markers of immunological and metabolic function.

METHODS

Eighteen patients undergoing elective upper gastrointestinal laparoscopic surgery were randomized to have insufflation achieved by using either helium (n = 8) or CO2 (n = 10) gas. Intraperitoneal pH was monitored continuously during surgery, and peritoneal macrophage function was determined by harvesting peritoneal macrophages at 5 min and 30 min after commencing laparoscopy, and then assessing their ability to produce tumour necrosis factor-alpha (TNF-alpha), and their phagocytic function.

RESULTS

Carbon dioxide laparoscopy was associated with a lower intraperitoneal pH at the commencement of laparoscopy, although this difference disappeared as surgery progressed. The production of TNF-alpha was better preserved by CO2 laparoscopy, but the insufflation gas used did not affect macrophage phagocytosis. Patients undergoing helium laparoscopy required less postoperative analgesia.

CONCLUSION

The choice of insufflation gas can affect intraperitoneal macrophage function in the clinical setting, and possibly acid-base balance. The present study suggested no immunological advantages for the clinical use of helium as an insufflation gas. The outcomes of the present study, however, are different to those obtained from previous laboratory studies and further research is needed to confirm this outcome.

MRI and diabetic foot infections

The role of magnetic resonance imaging and plain radiographs in evaluating osteomyelitis in the diabetic foot was studied. Fifty patients were prospectively examined by magnetic resonance imaging and plain radiographs to determine the extent of infection. Thirty-seven patients had positive MRI for osteomyelitis and 19 were positive with conventional radiography. Thirteen patients had negative MRI healed with short course of antibiotics. Five patients with positive MRI received four weeks' course of intravenous antibiotics with two still having persistent infection in the six weeks follow-up. Thirty-two patients underwent surgery with favorable results. Sixty-two bone specimens were obtained for histologic evaluation of osteomyelitis. In cases with histologic proof of diagnosis, magnetic resonance sensitivity was 99%, specificity was 81%, and accuracy was 94%. Thus magnetic resonance imaging was shown to have a high sensitivity, specificity, and accuracy in detecting osteomyelitis.

Experimental study of the effect of intraperitoneal heparin on tumour implantation following laparoscopy

BACKGROUND

Conclusions drawn from clinical reports of port site metastases following laparoscopic resection of intra-abdominal malignancy are now supported by a burgeoning experimental literature which suggests that laparoscopy promotes tumour metastasis to wounds. This study investigated the effect of intraperitoneal blood and heparin on the incidence of tumour cell implantation and port site metastasis.

METHODS

Twenty-four Dark Agouti rats underwent laparoscopy with carbon dioxide insufflation and the instillation of a tumour cell suspension and/or blood into the peritoneal cavity. Rats were allocated randomly to one of the following study groups (six rats per group): (1) controls; (2) intraperitoneal blood (2 ml blood introduced from a syngeneic donor rat); (3) intraperitoneal heparin; (4) intraperitoneal blood and heparin. Rats were killed 7 days after the procedure, and the peritoneal cavity and port sites were examined for the presence of tumour.

RESULTS

Tumour implantation and port site metastases were reduced by the intraperitoneal administration of heparin, but increased by the presence of intraperitoneal blood.

CONCLUSION

The results of this study suggest that tumour implantation following laparoscopy is promoted by the presence of intraperitoneal blood and that this effect may be reduced by the use of intraperitoneal heparin.