Credentialing for robotic lobectomy: what is the learning curve? A retrospective analysis of 272 consecutive cases by a single surgeon.

Credentialing processes for surgeons seeking robotic thoracic surgical privileges are not evidence-based, and the learning curve has not been reported. The goal of this study is to review our experience with robotic lobectomies and provide evidence for the development of a more uniform credentialing process. We performed a retrospective review of the first 272 consecutive robotic lobectomies performed between 2011 and 2017 by a single surgeon with prior video-assisted thoracoscopic (VATS) experience. Primary outcomes were operative duration, blood loss, chest tube duration, length of hospital stay, intraoperative complication, and conversion to thoracotomy. The patients were subdivided by surgical date into two cohorts of 120 consecutive patients to compare differences in outcomes, thereby illustrating the learning curve. Between 2011 and 2017, 272 patients (median age 67.5 years) underwent a robotic lobectomy by a single surgeon. The majority of patients (157/272) had early stage (T1N0) adenocarcinoma. For the entire cohort, median operative time was 160 min (83-317 min). The median blood loss was 75 mL (10-4000 mL). Median chest tube duration was 2 days (1-23 days) and median hospital stay was 3 days (1-25 days). Intraoperative complications occurred in seven patients. Only six patients required conversion to thoracotomy. Using multivariable logistic regression, it was found that the age, gender, and stage do not factor into conversion to thoracotomy, but BMI was found to be a significant covariate (p 0.043). As the surgeon performs more surgeries, there is a significantly shorter operative time (p < 0.001), decreased blood loss (p < 0.001), and shorter hospital stay (p < 0.014). When the first 120 and last 120 surgeries were compared, there was significantly less blood loss (234.6 vs 78.69 cc, p < 0.001), shorter operative time (181.9 vs 147.4 min, p < 0.001), shorter tube duration (3.49 vs 3.11 days, p 0.007), and shorter length of stay (4.03 vs 3.48 days, p < 0.001), respectively. More intraoperative complications were observed during the first 120 surgeries (6/120) compared to the last 120 surgeries (0/120; Fischer exact p = 0.029). Regression model plots did not show any apparent and significant change points, but rather a steady improvement. The more cases the surgeon does, the better is the outcome in terms of operative duration, blood loss, post-operative length of stay and intraoperative complications. The learning curve for robotic surgery for a surgeon with prior VATS experience is that of a continuous improvement with experience instead of a particular change point. Since most thoracic surgeons who perform robotic-assisted surgery have already gotten past their VATS learning curves, they no longer have a definable learning curve for robotic surgery. Hence, if a surgeon is already proficient and credentialed to perform VATS lung resections, he or she is no longer faced with a significant learning curve for robotic lung resections, and should be credentialed to do so once he or she has undergone the appropriate training with the equipment and technology.

Committee II: Guidelines for cytologic sampling techniques of lung and mediastinal lymph nodes.

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pulmonary cytology including indications for bronchial brushings, washings, and endobronchial ultrasound guided transbronchial fine-needle aspiration (EBUS-TBNA), technical recommendations for cytological sampling, recommended terminology and classification schemes, recommendations for ancillary testing and recommendations for post-cytological management and follow-up. All recommendations are based on the expertise of the authors, an extensive literature review and feedback from presentations at national and international conferences. This document selectively presents the results of these discussions. The present document summarizes recommendations regarding techniques used to obtain cytological and small histologic specimens from the lung and mediastinal lymph nodes including rapid on-site evaluation (ROSE), and the triage of specimens for immunocytochemical and molecular studies.

Molecular events in bronchogenic carcinoma and their implications for therapy.

Lung cancer patients suffer a 15% overall survival despite advances in chemotherapy, radiation therapy and surgery. This unacceptably low survival rate is due to the usual finding of advanced disease at diagnosis. Detecting preneoplastic lesions and determining which invasive lesions are prone to metastasize or recur can be formidable tasks. Understanding the molecular events that occur during the multistep process of bronchogenic carcinogenesis may make these tasks more surmountable. Approaches leading to identification of patients susceptible to cancer formation include detection of poor metabolizers of carcinogens, those unable to repair genetic alterations, those with activated oncogenes or inactivated tumor suppressor genes, and those at risk of poor outcomes. Detection may be achieved at the cellular, chromosomal, genetic, or protein level. Novel therapies can then be developed that prevent tumor initiation into and promotion through the multistep carcinogenesis pathway, conversion from preneoplastic into invasive malignancies, and progression into metastasis or recurrences. Therapeutic success of chemoprevention can be followed by changes in molecular marker levels. Blockade of activated tumor-promoting oncogenes or replacement of inactivated tumor-suppressing or apoptosis-promoting genes can be achieved by gene therapy. Development of these novel molecular diagnostic and therapeutic strategies could result in prevention of cancer formation or at least prolongation of disease-free survival.

Step activity monitor: increased accuracy in quantifying ambulatory activity.

This study compares the accuracy of a two-dimensional accelerometer worn on the ankle (a step activity monitor) with that of an electronic, digital pedometer worn on the belt line. Twenty-nine human subjects were evaluated while they briskly walked 400 M, slowly walked 10 M, and ascended and descended a flight of stairs. The step activity monitor had less error in all activities; its mean absolute error was 0.54%, whereas that of the pedometer was 2.82%. The difference was more pronounced in obese subjects (body mass index greater than 30), with an overall mean absolute error of 0.48% for the step activity monitor and 6.12% for the pedometer (nearly 13 times that of the step activity monitor). For subjects with a body mass index less than 30, the step activity monitor had an overall error of 0.56% and the pedometer had an overall error of 1.56% (less than 3 times that of the step activity monitor). The absolute error of the pedometer was positively correlated with body mass index (r = 0.792, p < 0.0001) and weight (r = 0.753, p < 0.0001), whereas the error of the step activity monitor was not significantly correlated with either. Neither device was significantly biased by age, gender, or the presence of a lower-extremity joint prosthesis. The accuracy and additional capabilities, including a real-time memory record of activity, of the step activity monitor make it well suited for objectively quantifying ambulatory activity, especially for obese subjects.

Transduction of murine and human tumors using recombinant adenovirus vectors.

BACKGROUND: Most cytokine-based cancer gene therapy clinical trials have used labor-intensive, retrovirus-mediated strategies resulting in unpredictable gene expression. Recombinant AdV vectors were evaluated for easier, more reproducible gene transfer into 12 human melanoma, 2 murine fibrosarcomas, and 8 other tumor cell lines. METHODS: AdV vectors contained a reporter (Escherichia coli beta-galactosidase or firefly luciferase) or cytokine gene (human interleukin-2 [IL-2] or IL-7). Transduction efficiencies and expression levels were assessed by histochemical staining, flow cytometry, polymerase chain reaction, fluorometry, and enzyme-linked immunosorbent assay. Tumorigenicity was determined by subcutaneous injection of cells into syngeneic mice. RESULTS: All cell lines studied were transduced with AdV. Most cell lines exhibited 100% transduction efficiencies (by flow cytometry) at multiplicities of infection (MOI) epsilon 10. Gene expression correlated linearly with MOI, but a cytopathic effect was observed at MOI > 100 with all vectors. Nanogram gene expression levels were routinely achieved. Irradiation (30 Gy) minimally affected expression levels. Tumorigenicity of AdV-IL-2-transduced fibrosarcoma cells in mice was inversely related to IL-2 production. A majority of mice that rejected their tumor challenge were immune to tumor rechallenge. CONCLUSIONS: E1-deleted AdV vectors may prove useful in generating tumor vaccines ex vivo with high, transient cytokine expression levels.

In vivo trafficking of adoptively transferred interleukin-2 expanded tumor-infiltrating lymphocytes and peripheral blood lymphocytes. Results of a double gene marking trial.

Adoptive immunotherapy with tumor-infiltrating lymphocytes (TIL) and IL-2 appears to produce dramatic regressions in patients with metastatic melanoma and renal cancer. However, the in vivo mechanism of TIL function is not known. We conducted an UCLA Human Subject Protection Committee, Recombinant DNA Advisory Committee, and FDA-approved clinical trial using genetically-marked TIL to test the hypothesis that these cells have unique, tumor-specific in vivo trafficking patterns. TIL and PBL (as a control effector cell population) were isolated and expanded in parallel in vitro in IL-2-containing medium for 4-6 wk. During the expansion, TIL and PBL were separately transduced with the amphotropic retroviral vectors LNL6 and G1Na. Transduced TIL and PBL were coinfused into patients and their respective numbers measured in tumor, peripheral blood, and normal tissues; integrated provirus could be quantitated and distinguished by DNA PCR. Nine patients were treated (six melanoma, three renal) and received between 4.5 x 10(8) and 1.24 x 10(10) total cells. Both "marked" TIL and PBL could be detected circulating in the peripheral blood, in some patients for up to 99 d after infusion. Marked TIL and/or PBL could be detected in tumor biopsies in six of nine patients as early as day 6 and as late as day 99 after infusion. No convincing pattern of preferential trafficking of TIL vs. PBL to tumor was noted. Moreover, concurrent biopsies of muscle, fat, and skin demonstrated the presence of TIL/PBL in comparable or greater numbers than in tumor in five patients. The results of this double gene marking trial provide interesting insights into the life span and trafficking of adoptively transferred lymphocytes, but do not support the hypothesis that TIL specifically traffic to tumor deposits.

In vivo cancer gene therapy with a recombinant interleukin-2 adenovirus vector.

Recombinant adenovirus (AdV) vectors are highly efficient at in vitro and in vivo gene delivery. In vivo therapy of established murine fibrosarcoma and mammary carcinomas was attempted with intratumoral injections of a recombinant AdV vector in which the human interleukin-2 (IL-2) gene was driven by the cytomegalovirus enhancer/promoter. Delayed growth and rejection of some tumors could be achieved with a cumulative virus dose of 2 to 6 x 10(9) plaque-forming units in two or three divided doses. Lower viral doses were ineffective, and higher doses resulted in animal death due to IL-2 toxicity. Using AdV vectors with the marker genes beta-galactosidase and luciferase, it is clear that even small volume (10 to 20 microL) intratumoral injections result in substantial systemic delivery of a portion of the virus dose. These findings define the potential and limitations of in vivo AdV-based cancer gene therapy and provide support for strategies to develop tumor-specific vectors.

Ontogenetic development of nutrient transporters in rat intestine.

We measured intestinal brush-border uptakes of three sugars and three amino acids, plus intestinal morphometric parameters, in rats from the day of birth until adulthood. Rates of body weight gain had pronounced peaks in the suckling phase and again during weaning, separated by a dip at the onset of weaning. These two peaks coincided with peaks or plateaus in intestinal growth and in glucose (Glc) and proline (Pro) uptake capacities, which may provide the basis for high rates of body growth. Pro uptake declined relative to Glc uptake upon weaning, reflecting decreasing protein needs for growth and decreasing protein intake relative to carbohydrate intake. Fructose (Frc) and lysine uptake increased steeply on weaning, whereas galactose uptake declined relative to that of Glc. Rats prevented from normal weaning by being maintained on dry milk were generally similar to normal rats weaned onto chow. Notably, their Frc uptake still rose steeply on weaning despite low dietary Frc levels, suggesting hard-wired regulation of Frc transporter development. Our in vitro uptakes are similar to modern in vivo values in the same strain of rats. Nutrient uptake capacities exceed normal dietary intakes by only a modest safety margin.

Nutrient extraction by cold-exposed mice: a test of digestive safety margins.

We examined the size of the "safety margin," if any, by which the small intestine's daily capacities to absorb nutrients exceed prevailing daily intakes of those nutrients. This safety margin, also known as reserve capacity, is widely assumed to be enormously large. As a test, we suddenly transferred mice from an ambient temperature of 22 to 6 degrees C and measured food intake, apparent digestive efficiency, intestinal morphometrics, and intestinal brush-border uptake capacities for D-glucose and L-proline over the next 28 days. Food intake jumped 68% within the first 12 h and rose in 2 days to a new plateau level 2.5 times the previous intake. Nevertheless, apparent digestive efficiency remained unchanged, even within the first 12 h, and intestinal transit times also remained unchanged, implying the existence of at least some safety margin. Masses of the small and large intestine, liver, kidneys, and spleen nevertheless increased within 4 days by 16-20%. Glucose and proline uptakes per milligram intestine increased by approximately 5%, so that the intestine's summed uptake capacities for these solutes increased by 24-26%. The animal's intestinal adaptation expressed in these increased uptake capacities implies that safety margins at the new plateau value of food intake would otherwise have been dangerously narrow. Comparison of calculated summed uptake capacities with measured dietary intakes suggests that safety margins are approximately 220-300% in mice at 22 degrees C, only 27-50% in mice at 6 degrees C before intestinal adaptation, but 60-88% in mice at 6 degrees C after intestinal adaptation.

Expression of mammalian renal transporters in Xenopus laevis oocytes.

We have injected mRNA from rabbit renal cortex into Xenopus oocytes and demonstrated the expression of renal carriers for Na(+)-independent transport of L-phenylalanine and L-lysine and Na(+)-dependent transport of L-alanine and succinate. Maximal expression of renal amino acid transporters occurred 6-8 days following mRNA injection. The proteins responsible for transport of these four substrates were translated from mRNAs which are between 1.5 and 3.0 kb. This information serves as a starting point for expression cloning of these transport proteins.

Ontogenetic development of nutrient transporters in bullfrog intestine.

The ratio of intestinal glucose (Glc) to amino acid (AA) transporter activity rises with age in animals of species in which the ratio of dietary carbohydrate to protein also rises. Does this shift function to match transporter activity to current dietary substrate levels or to the high AA requirements of young growing animals? We compared intestinal brush-border uptake of Glc and the AA proline (Pro) in adult and tadpole bullfrogs, since with age this species changes from an herbivore to a carnivore and hence its dietary carbohydrate-to-protein ratio decreases rather than increases. Like typical adult herbivores, tadpoles have a long, highly coiled, narrow-bore, thin-walled intestine with a long, heavy colon, whereas adult bullfrogs have a short, wide-bore, thick-walled intestine typical of carnivores. The ratio of Glc to Pro uptake capacity is essentially the same in adults as in larval tadpoles and is typical of carnivores but unprecedently low for herbivores. This suggests that both functions proposed for developmental shifts of Glc and AA transport in other species are significant and that their effects cancel each other in bullfrogs. Transporter kinetic constants vary predictably with developmental stage. Intestinal daily uptake capacity is comparable to actual daily intake for Glc in adults and for Pro in both tadpoles and adults but is much lower than intake for Glc in tadpoles, probably because most carbohydrate ingested by tadpoles is in the form of high molecular weight polymers that are not utilized.

Ontogenetic development of transporter regulation in bullfrog intestine.

Intestinal nutrient transporter activity is adapted to dietary substrate levels on three time scales: reversibly, within an adult individual, to rapid dietary changes; developmentally, to normal ontogenetic changes in diet; and evolutionarily, among carnivores, omnivores, and herbivores, to a species' natural diet. Does the capacity for rapid reversible adaptation itself vary adaptively during development? Substrate-dependent regulation would make functional sense in herbivorous/omnivorous tadpoles in which dietary substrate levels fluctuate unpredictably, but would serve no purpose in strictly carnivorous adult bullfrogs in which dietary protein is always high and carbohydrate is low. Hence, we fed premetamorphosis bullfrog tadpoles either boiled lettuce (high in carbohydrate, low in protein) or ground beef (high in protein, low in carbohydrate). Gut weight relative to body weight was higher in lettuce-fed tadpoles. Glucose uptake was greater and proline uptake slightly less in lettuce-fed than in beef-fed tadpoles. The resultant ratio of glucose uptake capacity to proline uptake capacity was nearly twice as high in lettuce-fed as in beef-fed tadpoles, corresponding to a much higher ratio of dietary carbohydrate to protein. Adult frogs have been shown to lack such regulation. Therefore, the regulatory capacity seen in tadpoles must become lost during amphibian metamorphosis.

Changes in the expression of beta and gamma actins during differentiation of PC12 cells.

Cells of the rat pheochromocytoma line PC12 cease proliferation and develop neurites in response to nerve growth factor (NGF). Quantification of beta and gamma isoforms of nonmuscle actin in extracts of these differentiating cells showed that the beta:gamma ratio decreased from 1.30 +/- 0.05 to 0.99 +/- 0.05 after 6 days of NGF treatment. Cells treated with N6,O2-dibutyryl cyclic AMP (dbcAMP) also showed a shift in the ratio of beta:gamma isoforms, although few of these cells extended neurites. Administration of dbcAMP or both NGF and dbcAMP to cells accelerated the decrease in the beta:gamma actin isoform ratio relative to treatment with NGF alone. Those cells treated with both NGF and dbcAMP also showed an accelerated rate of neurite outgrowth. Suspension-grown PC12 cells treated with NGF showed neither an isoform ratio decrease nor neurite development. Our results suggest that either cyclic AMP may be a "second messenger" for NGF or it may effect the isoform ratio change by an independent mechanism. In addition, our data demonstrate an alteration in actin isoform expression, which accompanies the morphological differentiation of PC12 cells.