Metacommunity structure preserves genome diversity in the presence of gene-specific selective sweeps under moderate rates of horizontal gene transfer

The horizontal transfer of genes is fundamental for the eco-evolutionary dynamics of microbial communities, such as oceanic plankton, soil, and the human microbiome. In the case of an acquired beneficial gene, classic population genetics would predict a genome-wide selective sweep, whereby the genome spreads clonally within the community and together with the beneficial gene, removing genome diversity. Instead, several sources of metagenomic data show the existence of "gene-specific sweeps", whereby a beneficial gene spreads across a bacterial community, maintaining genome diversity. Several hypotheses have been proposed to explain this process, including the decreasing gene flow between ecologically distant populations, frequency-dependent selection from linked deleterious allelles, and very high rates of horizontal gene transfer. Here, we propose an additional possible scenario grounded in eco-evolutionary principles. Specifically, we show by a mathematical model and simulations that a metacommunity where species can occupy multiple patches, acting together with a realistic (moderate) HGT rate, helps maintain genome diversity. Assuming a scenario of patches dominated by single species, our model predicts that diversity only decreases moderately upon the arrival of a new beneficial gene, and that losses in diversity can be quickly restored. We explore the generic behaviour of diversity as a function of three key parameters, frequency of insertion of new beneficial genes, migration rates and horizontal transfer rates.Our results provides a testable explanation for how diversity can be maintained by gene-specific sweeps even in the absence of high horizontal gene transfer rates.

Clonal cooperation through soluble metabolite exchange facilitates metastatic outgrowth by modulating Allee effect

Cancers feature substantial intratumoral heterogeneity of genetic and phenotypically distinct lineages. Although interactions between coexisting lineages are emerging as a potential contributor to tumor evolution, the extent and nature of these interactions remain largely unknown. We postulated that tumors develop ecological interactions that sustain diversity and facilitate metastasis. Using a combination of fluorescent barcoding, mathematical modeling, metabolic analysis, and in vivo models, we show that the Allee effect, i.e., growth dependency on population size, is a feature of tumor lineages and that cooperative ecological interactions between lineages alleviate the Allee barriers to growth in a model of triple-negative breast cancer. Soluble metabolite exchange formed the basis for these cooperative interactions and catalyzed the establishment of a polyclonal community that displayed enhanced metastatic dissemination and outgrowth in xenograft models. Our results highlight interclonal metabolite exchange as a key modulator of tumor ecology and a contributing factor to overcoming Allee effect-associated growth barriers to metastasis.

A fitness trade-off explains the early fate of yeast aneuploids with chromosome gains

The early development of aneuploidy from an accidental chromosome missegregation shows contrasting effects. On the one hand, it is associated with significant cellular stress and decreased fitness. On the other hand, it often carries a beneficial effect and provides a quick (but typically transient) solution to external stress. These apparently controversial trends emerge in several experimental contexts, particularly in the presence of duplicated chromosomes. However, we lack a mathematical evolutionary modeling framework that comprehensively captures these trends from the mutational dynamics and the trade-offs involved in the early stages of aneuploidy. Here, focusing on chromosome gains, we address this point by introducing a fitness model where a fitness cost of chromosome duplications is contrasted by a fitness advantage from the dosage of specific genes. The model successfully captures the experimentally measured probability of emergence of extra chromosomes in a laboratory evolution setup. Additionally, using phenotypic data collected in rich media, we explored the fitness landscape, finding evidence supporting the existence of a per-gene cost of extra chromosomes. Finally, we show that the substitution dynamics of our model, evaluated in the empirical fitness landscape, explains the relative abundance of duplicated chromosomes observed in yeast population genomics data. These findings lay a firm framework for the understanding of the establishment of newly duplicated chromosomes, providing testable quantitative predictions for future observations.

Abstract 2613: A modified Luria-Delbrück assay allows quantification of colorectal cancer persister cells’ mutation rate

When cancer cells are exposed to lethal doses of targeted therapies, the emergence of a subpopulation of drug-tolerant persister cells (DTPs) is often observed. We previously reported that colorectal cancer (CRC) cells exposed to targeted therapies activate an adaptive mutability stress response, involving DNA damage induction and a switch to low-fidelity DNA replication. Therefore, targeted treatment might lead to increased mutation rate in DTPs, but mutation rates of cancer cells during treatment have not been quantitatively assessed. Here, we combined biological experiments and mathematical modelling to characterize emergence and dynamics of DTPs. From this, we extrapolated parameters governing dynamics of cancer cells populations and designed a modified Luria-Delbrück assay on mammalian cells (MC-LD) to quantify mutations rates of CRC cells under standard growth conditions and during exposure to targeted therapy. We selected mismatch repair proficient CRC cell lines sensitive to different clinically used therapeutic agents, and derived clones to be used for experiments. By monitoring cell dynamics in drug-response growth assays, we found that CRC cells exposed to targeted therapy display a biphasic killing curve reaching a stable plateau, a pattern indicative of emergence of DTPs. By fitting model estimation to population growth assays, we predicted that, even if a subgroup of DTPs predated treatment, the majority of them emerged only upon exposure to targeted therapies. We also observed that DTPs slowly replicate under treatment, as shown by Carboxy fluorescein succinimidyl ester (CFSE) analysis and staining with 5-ethynyl-2’-deoxyuridine (EdU). We used these population dynamics parameters to design the MC-LD assay. CRC clones were plated in several 96-multiwell plates each, and after an expansion phase in standard culture conditions, treatment was added. After 3-4 weeks, a minority of wells showed growth of resistant colonies: based on the measured growth rates, we could predict that the resistant cells arose before treatment by spontaneous mutation. The remaining wells contained a homogenous population of DTPs. After several weeks of treatment, when pre-treatment resistant clones would have already emerged, late-emerging resistant colonies appeared in a subset of wells in which DTPs had previously been detected. Using the number of residual DTPs and resistant colonies to infer mutation rates, we found a 7- to 50-fold increase (depending on the cell line) in DTPs’ mutation rate compared to sensitive cells.In conclusion, we developed a new assay which allows quantitative comparisons of spontaneous and drug-induced mutation rates in cancer cells and showed that adaptive mutability in DTPs leads to increased mutation rates. This approach could be used to measure whether and how a wide range of environmental conditions affect DTP phenotype and mutation rates in mammalian cells.

Citation Format: Alberto Sogari, Mariangela Russo, Simone Pompei, Mattia Corigliano, Giovanni Crisafulli, Andrea Bertotti, Marco Gherardi, Federica Di Nicolantonio, Marco Cosentino Lagomarsino, Alberto Bardelli. A modified Luria-Delbrück assay allows quantification of colorectal cancer persister cells’ mutation rate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2613.

Epistasis, aneuploidy, and functional mutations underlie evolution of resistance to induced microtubule depolymerization

Cells with blocked microtubule polymerization are delayed in mitosis, but eventually manage to proliferate despite substantial chromosome missegregation. While several studies have analyzed the first cell division after microtubule depolymerization, we have asked how cells cope long-term with microtubule impairment. We allowed 24 clonal populations of yeast cells with beta-tubulin mutations preventing proper microtubule polymerization, to evolve for ˜150 generations. At the end of the laboratory evolution experiment, cells had regained the ability to form microtubules and were less sensitive to microtubule-depolymerizing drugs. Whole-genome sequencing identified recurrently mutated genes, in particular for tubulins and kinesins, as well as pervasive duplication of chromosome VIII. Recreating these mutations and chromosome VIII disomy prior to evolution confirmed that they allow cells to compensate for the original mutation in beta-tubulin. Most of the identified mutations did not abolish function, but rather restored microtubule functionality. Analysis of the temporal order of resistance development in independent populations repeatedly revealed the same series of events: disomy of chromosome VIII followed by a single additional adaptive mutation in either tubulins or kinesins. Since tubulins are highly conserved among eukaryotes, our results have implications for understanding resistance to microtubule-targeting drugs widely used in cancer therapy.

Predictive Modeling of Influenza Shows the Promise of Applied Evolutionary Biology

Seasonal influenza is controlled through vaccination campaigns. Evolution of influenza virus antigens means that vaccines must be updated to match novel strains, and vaccine effectiveness depends on the ability of scientists to predict nearly a year in advance which influenza variants will dominate in upcoming seasons. In this review, we highlight a promising new surveillance tool: predictive models. Based on data-sharing and close collaboration between the World Health Organization and academic scientists, these models use surveillance data to make quantitative predictions regarding influenza evolution. Predictive models demonstrate the potential of applied evolutionary biology to improve public health and disease control. We review the state of influenza predictive modeling and discuss next steps and recommendations to ensure that these models deliver upon their considerable biomedical promise.

Phylogenetic properties of RNA viruses

A new word, phylodynamics, was coined to emphasize the interconnection between phylogenetic properties, as observed for instance in a phylogenetic tree, and the epidemic dynamics of viruses, where selection, mediated by the host immune response, and transmission play a crucial role. The challenges faced when investigating the evolution of RNA viruses call for a virtuous loop of data collection, data analysis and modeling. This already resulted both in the collection of massive sequences databases and in the formulation of hypotheses on the main mechanisms driving qualitative differences observed in the (reconstructed) evolutionary patterns of different RNA viruses. Qualitatively, it has been observed that selection driven by the host immune response induces an uneven survival ability among co-existing strains. As a consequence, the imbalance level of the phylogenetic tree is manifestly more pronounced if compared to the case when the interaction with the host immune system does not play a central role in the evolutive dynamics. While many imbalance metrics have been introduced, reliable methods to discriminate in a quantitative way different level of imbalance are still lacking. In our work, we reconstruct and analyze the phylogenetic trees of six RNA viruses, with a special emphasis on the human Influenza A virus, due to its relevance for vaccine preparation as well as for the theoretical challenges it poses due to its peculiar evolutionary dynamics. We focus in particular on topological properties. We point out the limitation featured by standard imbalance metrics, and we introduce a new methodology with which we assign the correct imbalance level of the phylogenetic trees, in agreement with the phylodynamics of the viruses. Our thorough quantitative analysis allows for a deeper understanding of the evolutionary dynamics of the considered RNA viruses, which is crucial in order to provide a valuable framework for a quantitative assessment of theoretical predictions.

Salvage of infected vascular graft via 'perivascular venous banding' technique coupled with rectus abdominis myocutaneous muscle flap transposition

This is the case of a severe Pseudomonas aeruginosa biological vascular graft infection, completely involving the perianastomotic tract of a femoro - femoral crossover bypass and resulting in repeated bleeding from the offended vessel wall. After the failure of a sartorious rotational muscle flap transposition into the infected groin wound, this 'high-grade' vascular graft infection was finally treated successfully by wrapping a great saphenous vein patch reinforcement circumferentially around the damaged biological vascular conduit and filling the infected wound with a rectus abdominis myocutaneous muscle flap transposition. The aim of this report is to illustrate this novel, to our knowledge, 'perivascular venous banding' technique and to evaluate the prospective of future testing of this surgical procedure. Starting from this singular case, we will also review the role of the rotational muscle flaps in the conservative management of major vascular graft infections.

On the accuracy of language trees

Historical linguistics aims at inferring the most likely language phylogenetic tree starting from information concerning the evolutionary relatedness of languages. The available information are typically lists of homologous (lexical, phonological, syntactic) features or characters for many different languages: a set of parallel corpora whose compilation represents a paramount achievement in linguistics. From this perspective the reconstruction of language trees is an example of inverse problems: starting from present, incomplete and often noisy, information, one aims at inferring the most likely past evolutionary history. A fundamental issue in inverse problems is the evaluation of the inference made. A standard way of dealing with this question is to generate data with artificial models in order to have full access to the evolutionary process one is going to infer. This procedure presents an intrinsic limitation: when dealing with real data sets, one typically does not know which model of evolution is the most suitable for them. A possible way out is to compare algorithmic inference with expert classifications. This is the point of view we take here by conducting a thorough survey of the accuracy of reconstruction methods as compared with the Ethnologue expert classifications. We focus in particular on state-of-the-art distance-based methods for phylogeny reconstruction using worldwide linguistic databases. In order to assess the accuracy of the inferred trees we introduce and characterize two generalizations of standard definitions of distances between trees. Based on these scores we quantify the relative performances of the distance-based algorithms considered. Further we quantify how the completeness and the coverage of the available databases affect the accuracy of the reconstruction. Finally we draw some conclusions about where the accuracy of the reconstructions in historical linguistics stands and about the leading directions to improve it.

[Mechanical microanastomosis in reconstructive surgery of the neck and face]

Aim of the study is to report our preliminar experience with MCA Coupler System in mechanical microanastomoses performed in head and neck reconstructive surgery. During almost 7 months we performed 7 end-to-end venous anastomoses: 3 of them regarding the cephalic district. We had no vascular thrombosis, vascular congestion or flap loss. Mean time of execution of anastomosis with MCA Coupler System was 10 minutes. In our experence it is essential the choice of the appropriate size of the device and a good dissection of recipient vessels. In our opinion the Coupler System is an easy applicable device, and an efficient alternative to manual micro-anastomoses.

[Expanders and the prosthetic short line in breast reconstruction after mastectomy: experience with the first 130 surgically treated cases]

Breast reconstruction as now to be consider as a complementary treatment of breast cancer surgery. Between 1998-1999 we developed a project of collaboration with Polytech-Silimed Europe Gmbh for a new textured tissue expander. This new system allows expansion of the middle and lower quadrant of the breast acting a physiologic ptosis of the breast. Authors report their experience on the first 130 patients.

[Five hundred sixty-nine flaps used in reconstruction of the head and neck: morbidity analysis and results]

Aim of the study is to provide high-level results in terms of functionality and softness of the tissues achieved with different reconstructive techniques performed in oncological surgery of the head and neck. Test group was composed of 528 patients recovered with a diagnosis of head and neck cancer. We performed 569 flaps: myocutaneous, cutaneous and fasciocutaneous, and free flaps. The clinical outcome and the morpho-functional evaluation show that free flaps can ensure excellent results, especially in defined anatomical areas such as the cervical-esophageal region, jaw and tongue. As to myocutaneous and cutaneous/fasciocutaneous flaps, they are still the first reconstructive choice, according to their minimal or no functional implications.

[500 reconstructive flaps in oncological surgery of the head and neck: critical review of 10 years experience]

AIM

Oncologic surgery of the head and neck, according to the principle of oncological radicality, involves large demolition often including skin, soft tissues and bone structures. The aim of this study is to provide a high-level perspective of results achieved in terms of functionality and softness with the different reconstructive techniques during the last ten years.

METHODS

The test group was composed of 467 patients, hospitalised in the "Regina Elena" National Cancer Institute in Rome and treated for head and neck cancer; 86% of the treated patients suffered from stage III or IV of the disease. For the reconstructive phase, 506 flaps were used, 45.5% were myocutaneous flaps, 37.1% cutaneous and fasciocutaneous flaps and 17.4% free flaps. Ischemic complications occurred in 5.2% of the myocutaneous flaps group and in 10.3% of the free flaps group.

RESULTS

"Minor complications" affected 3.9% of the cases in the free flaps group and 20.8% of cases in the myocutaneous flaps group.

CONCLUSION

The analysis of the results shows that generally free flaps are more reliable than myocutaneous flaps in terms of minor complications, however they tend to prolong the patient's hospitalisation and increase the overall treatment cost. Furthermore in morpho-functional terms, free flaps ensure results, in defined anatomical areas (such as the cervical-esophageal region, jaw, tongue) that today cannot be compared to the "conventional" procedures. As for myocutaneous and cutaneous/ fasciocutaneous flaps, according to personal opinion they are still the first choice for reconstruction having minimal or no functional implications.

A new surgical technique for the correction of the inverted nipple

Many techniques have been proposed over the years to correct the inverted nipple, a condition which causes both aesthetic and functional problems. In more severe cases, other than causing infections and inflammations, breastfeeding is impossible because of the lack of nipple erection. Reconstructive surgical techniques today are oriented toward methods that allow adequate filling to maintain the nipple permanently everted. In the technique we propose, the nipple is pulled out and extruded by way of a periareolar incision after sectioning the galactophorous ducts and fibrous tissue. To guarantee a permanent eversion, a single trilobed dermoglandular flap is created, overturned, and fixed to fill the "dead space" below the nipple after the lobes have been sutured together. Finally, two transfixed U-shaped sutures are employed to keep the flap in place. From an analysis of the various techniques and results obtained, this method appears to be effective above all in resolving the aesthetic problem in a stable manner and is simpler than the techniques that employ multiple flaps.

Age as a risk factor in cervicofacial reconstruction

The Authors report their experience from January 1980 to January 1998 with 392 reconstructive flaps for the oncological reconstruction of the cervicofacial district. One hundred and forty-two were conventional flaps, 187 were myocutaneous or pedicled muscular ones and 63 were microvascular. Ninety percent of the patients had Stage IV disease, 80% were tumors involving the oral cavity structures, 40% of the patients had received preoperative radiotherapy; 35% of the cases were recurrences. The complications related to the surgery were evaluated for each type of flap, comparing them to the same flaps employed in patients > 70. Complications were divided into major and minor that were observed at an overall rate of 22%. With the use of conventional flaps, there was an 11.3% rate of minor complications and a 5.6% rate of major ones. Examining the 187 myocutaneous or pedicled muscular flaps, 21% of the overall 27% were minor and 6% were major complications. Of the remaining 63 free flaps, minor complications were observed in 4.7% and major complications in 14.2% of cases. Thirty-four of the 392 flaps, 24 of which were myocutaneous or pedicled muscular and 10 free flaps, were utilized in elderly patients and compared with the 216 of the same type, in patients < 70. A comparative analysis shows that there was a major complication rate of 11.7% in the flaps employed on the elderly patients as opposed to 7.9% for those employed in the younger patients. In terms of minor complications, a 20.5% complication rate was observed for those > 70 as opposed to 16.7% for patients < 70. A more detailed analysis of these data, enabled to postulate that the smaller group of flaps used in elderly patients is statistically influenced by the "dilution" of the complication rate in favour of the larger group of younger patients. Furthermore, by appropriately correcting the risk factors due to concomitant diseases that were not related to surgery in the older patients, a realignment of the results may be seen. Therefore, a careful preoperative study must be carried out in the elderly patients with cervicofacial tumors who are eligible for surgery to establish and possibly treat the concomitant disease responsible for the increased peri- and postoperative morbidity. In conclusion, complications in elderly patients are correlated to the state of co-morbidity and neither to age nor to the duration of the operation. Responsiveness may therefore be obtained also in elderly patients employing sophisticated techniques such as microvascular flaps.

[Free radial forearm flap and myocutaneous flaps in oncological reconstructive surgery of the oral cavity, Comparison of functional results]

In modern multi-disciplinary cancer treatment, rehabilitation and functional results represent utmost intent in reconstructive surgery of the oral cavity. Even in cases where the stage of disease is advanced) and the perspective of survival is limited, it is possible to achieve an acceptable quality of life. The authors report, in this study, the morpho-functional results and the morbidity observed in glossectomies in which the reconstruction was performed using three different methods. In a total of 264 reconstructive flaps of the head and neck regions, the authors considered three groups of 15 patients that had had reconstruction after the demolitive procedure. Respectively these groups were divided by the followed methods: free forearm flap, pectoralis major myocutaneous flap and nasolabial flap. The morbidity showed an extremely low rate of flap loss in all the groups, but "minor" complications, such as fistulas and leakages, were significantly more frequent in the myocutaneous flaps group. Functional evaluation for speech and deglutition showed good results in most patients. Extremely severe postoperative conditions as a permanent NG tube or incomprehensible speech had been observed in less than 15% of the cases. Particularly, the pectoralis major flap, showed its best functional performances in the total or subtotal glossectomies with a sacrifice of the muscles of the oral floor. The free forearm flap is reliable and safe with its low thickness and pliability, especially for partial glossectomies. The nasolabial flap was confirmed to be the first reconstructive choice for selected limited resections of the tongue and of the antero-lateral floor. With this experience it is possible, even in more complex free flaps, to reduce the time consumption and the complication rate. Free flaps do not substitute routinely myocutaneous and conventional flaps, but they represent the "ideal" reconstructive alternatives for specific and selected indications.

[Reconstruction using pedicle and free flaps in partial or total resections of the hypopharyngeal-esophageal tract]

Modern surgical treatment of cancer of the hypopharyngo-esophageal cannot be conditioned by the reconstructive procedures. Reconstructive options are based on the size and position of the defect in this important anatomical region. Currently the reconstruction of the hypopharyngo-esophageal tract allows a rapid and suitable restoration of the vital functions, a low morbidity and shortened hospital stay. The purpose of this study was to compare the various reconstructive approaches in terms of morbidity and functional results. Between January 1990 and June 1994, 17 patients with hypopharyngo-esophageal tract malignancies and one with a stenosis received treatment. The reconstructive procedures included 19 flaps: five myocutaneous pectoralis major flaps, one myocutaneous trapezius flap, five deltopectoral flaps, one radial forearm free flap and seven free jejunal grafts. There were six complications: one total necrosis and two stenosis in the free jejunal grafts group, one partial necrosis and one dehiscence in two myocutaneous pectoralis major flaps and one stenosis in a deltopectoral flap. Based on our studies, we believe that the free jejunal graft is the first choice for total reconstruction of the hypopharyngo and cervical esophageal tract. However the radial forearm free flap is certainly a valid solution for subtotal hypopharyngo-esophageal reconstruction. Pedicled flaps and particularly the myocutaneous pectoralis major flaps are a good alternatives for limited reconstructions (< 50%) of the hypopharyngo-esophageal tract.

[Reconstructive oncologic surgery of the head and neck. Morbidity and comparative results of conventional and myocutaneous flaps]

The authors analyzed the data obtained from their experiences in extensive head and neck resections, and, reconstructive treatments using myocutaneous and conventional flaps. They tried to evaluate comparatively the reconstructive approach, in terms of morbidity and functional results. The 145 cases of advanced had and neck cancer, treated from January 1990 to January 1994, were considered in this study. The reconstructive procedures consisted of 193 flaps. In this study, 106 were myocutaneous flaps (pectoralis major or trapezius flap); 72 were conventional flaps (fasciocutaneous, cutaneous or muscular only) and the remainder were 15 free flaps. The morbidity related to both flap procedures had been low: 33% in myocutaneous flaps versus 11% in conventional flaps. This report demonstrated the versatility, usefulness, and reliability of both kinds of these reconstructive procedures, especially in intra-oral reconstruction. The expected morphological and functional results were quite encouraging in terms of swallowing and speech.

[The rectus abdominis free flap in reconstructive surgery of the head and neck]

The Authors describe their preliminary experience with rectus abdominis free flap in reconstructive surgery of the head and neck. Out of the 29 cases of microsurgery in treating head and neck tumours, four inferior rectus abdominis free tissue transfers were used: two for complex intraoral reconstruction and two for composite facial defects. There was one flap loss due to late infection in the region of anastomosis, while there were two complications in the remaining three cases. The morphological and functional results have proved to be highly satisfactory. The flap, based on the deep inferior epigastric vessels, appears to be versatile in terms of skin island design, thickness and length of the pedicle. As with the forearm free flap, the inferior rectus abdominis has the advantage of offering the possibility of simultaneous demolition and reconstruction in one surgical session. The Authors conclude that the low morbidity concerned with this microvascular flap, also reported in international literature, confirm its validity as a soft tissue transfer in the in the treatment of advanced head and neck cancer.

[Total/near-total glossectomy for advanced carcinoma of the tongue]

Poor survival rates and the limited palliation afforded by radiotherapy alone, together with progress made in reconstructive surgery in restoring mucosal continuity after large resections, make total glossectomy reasonably indicated for treatment of advanced carcinoma of the tongue. The Authors reviewed 19 cases (17 males, 2 females, mean age 58.4 years) of total and near total glossectomy without laryngectomy treated at National Cancer Institute "Regina Elena" of Rome from 1990 to 1993 in order to evaluate oncological and functional results. All patients were reconstructed immediately, 16 with a pectoralis major flap, 2 with a nasolabial flap and 1 with a radial forearm free flap and were available for follow-up from 6 to 45 months (mean 29 months). There was no operative mortality and no patient needed total laryngectomy for aspiration. The rate of local recurrencies was 52.6%, most of them (75%) in patients who had undergone total/near total glossectomy for recurrence. Survival rate was 61.5% after 1 year and 20% after 2 years. 94% of patients resumed swallowing and independent oral alimentation (48% of them without any dysphagia); 84%; of the patients were decannulated and 48% produced easily intellegible speech. Data from our experience let us conclude that, in the light of the acceptable functional results obtained with reconstructive flaps, total glossectomy should be considered as the primary treatment modality in advanced carcinoma of the tongue (including T2 > 3 cm exceeding midline), and should not be reserved only for salvaging hopeless situations.

[Morbidity and the morphofunctional aspects of myocutaneous flaps used in the head and neck area]

The authors analysed the data obtained from their experiences in extensive head and neck resections as well as reconstructive treatments using myocutaneous flaps. They tried to evaluate the reconstructive approach in terms of morbidity and functional results. Sixty-nine patients, treated from January 90 to November 92 for advances intra-oral cancer, were considered in this study. The reconstructive procedure in 68 cases was the pectoralis major myocutaneous flap while in 5 cases the trapezius flap was utilized. Even though the oncological results were poor, the functional ones were quite encouraging. In fact, the assessment of speech and swallowing was extremely satisfactory in 83% of the cases. The morbidity related to both flap procedures was low and the patients' life quality was good. Indeed, the use of a free flap offers additional advantages, without necessarily compromising safety of the reconstruction. Free flaps in general allow greater leeway in flap design and donor-site choice than pedicled flaps. Several reports have already demonstrated the versatility, usefulness and reliability of these flaps, especially in intra-oral reconstruction. The intricate nature of microsurgery and the expense of microsurgical equipment inhibit this kind surgery in many institutions around the world where the standard myocutaneous flaps would be a more practical procedure. In conclusion, even those patients with a poor prognosis may be considered potential candidates for demolitive and reconstructive treatment with which satisfactory results may be obtained.

[Excisional and reconstructive treatment of stage IV tumors in the oral cavity. Results and limits]

The patients with advanced stages of intraoral cancer, having a limited life expectancy, are often considered non-surgical cases. Radiochemotherapy does not warrant an acceptable quality of life. The authors analysed the data obtained from their experiences in resections that had been extensive, as well as, reconstructive treatment of these kinds of neoplasms. They tried to evaluate the demolitive and reconstructive approach, in terms of morbidity, functional results and survival rate. Thirty-six patients, treated from January 1990 to August 1991 for advanced intraoral cancer, were considered in this study; 58% of the cases had primary tumors and 42% had recurrences. The reconstructive procedure used in all cases, was the pectoralis major myocutaneous flap. Even though the expected oncological results had been poor, the functional ones, had been quite encouraging. In fact, the assessment of speech and swallowing was extremely satisfactory, respectively in 82% and 89% of cases. The morbidity related to the flap procedure had been low. The quality of the residual life of the patients was good, especially if compared with the life of those patients who had not been treated. In conclusion, the authors maintain that even patients with limited prognosis may be considered as potential candidates for demolitive and reconstructive treatment.

[Immediate breast reconstruction. A retrospective analysis of 7 years' experience]

The collaboration between oncological and plastic surgeons proved to be essential in the multifaceted treatment of the neoplasms and high-risk lesions of the breast. It guarantees psychological advantages, and improves the quality of life of the patient, who is a candidate for demolition surgery. The authors analyse the results obtained over a 7-year period, through their experiences of 98 immediate breast reconstructions performed after subcutaneous simplex, Patey or Halsted mastectomies. They assessed the validity of this approach due to the brilliant esthetic results obtained, the minimal surgical time, and the low morbidity.

[Postmastectomy breast reconstruction using myocutaneous rectus abdominalis flap. Our experience]

The paper compares the results of 34 patients undergoing reconstructive surgery following radical mastectomy using a TRAM flap with those reported in the literature. The parameters taken into consideration in this study were indications for reconstructive surgery, morbidity and the results of reconstruction. The monopedicle flap offered good cosmetic results and a low rate of complications if correctly and selectively used. This selection should exclude high-risk patients. The bipedicle flap is an effective alternative and the morbidity rate was no higher among the abdominal donor.

[External trans-columella access to nasal surgery. Results and impressions in 51 operated cases]

The Authors report their personal experience relating to 51 cases of nose plastic surgery using an external trans-columella access route. From an evaluation of results, it emerges that by allowing full exposure of the nasal cartilaginous structure, this technique is ideally suited to the treatment of congenital deformities, and post-traumatic and iatrogenic consequences. Given the good esthetic results of the cutaneous scar, with which all subjects were satisfied, this method might also be proposed in selected cases of nose plastic surgery for esthetic reasons. Extremely pointed, bifurcate or bulbous nose can easily be treated given the direct and "dynamic" view of the anatomic peculiarities present. In conclusion, the advantages offered by external access outweight its "invasiveness", which appears to be more theoretical than that observed during follow up.

[Immediate reconstructive approach in neoplastic pathology and "high risk" of the breast]

One of the most important aims in oncology should be the quality of life, even in the cases of limited life expectancy. With this objective, the Authors report their experience of immediate breast reconstruction after surgical treatment for neoplasms and "high risk" lesions. In 76 cases they analyzed aesthetic results and morbidity. In immediate reconstruction after Patey mastectomies, the tissue expanders offered good cosmetic results with an acceptable complication rate in comparison with more complex methods as myocutaneous flaps. These flaps represent the alternative in selected cases of Halsted mastectomies, where the mutilation is not acceptable to the patient. In "high risk" lesions surgical approach, namely subcutaneous mastectomy, may be proposed in selected cases only. The Authors emphasize that subcutaneous mastectomy with an immediate submuscular reconstruction offer good aesthetic results especially in small size breasts with mild ptosis. The capsular contracture is however significant in 25% of the patients treated with these techniques.

[Immediate breast reconstruction and oncologic criteria: our current definition]

After a review of the literature, the authors attempt at a definition of the oncologically safe candidate to an immediate reconstruction after modified radical mastectomy for breast cancer. The analysis of the natural history of locally recurrent breast cancer indicates that the potential for its masking is negligible. Survival curves of patients submitted to immediate breast reconstruction are similar to those reported for historical controls. The ideal candidate for an immediate reconstruction is a stage I (negative axillary nodes) patient. As immediate breast reconstruction does not alter the prognosis of breast cancer patients nor does it harm the use of adjuvant therapies, the authors believe that even a well motivated stage II (positive axillary nodes) patient should be considered as a candidate for an immediate reconstructive procedure.

Peritoneovenous shunt and neoplastic ascites: a 5-year experience report

The cases of 42 patients with malignant ascites treated with a peritoneal venous shunt over a 5-year period are reviewed to establish the incidence of surgical and postsurgical complications. Although the yield of malignant cells found in the peripheral blood was increased after shunting, no new hematogenous metastases were observed after the operation. No evidence of disseminated intravascular coagulation was observed after shunt placement. While the shunt effectively relieved the discomfort due to abdominal distention and respiratory impairment, no restoration of cutaneous hypersensitivity was observed in the nine patients who were anergic prior to surgery. The median survival of patients with breast and gynecological cancer, after surgery, was significantly longer than the survival of patients with primary gastrointestinal neoplasma. In conclusion, peritoneal venous shunt appears to be an effective and safe method to improve the quality of life of patients with malignant ascites.