Site specific nematode management-development and success in cotton production in the United States.

Variability in edaphic factors such as clay content, organic matter, and nutrient availability within individual fields is a major obstacle confronting cotton producers. Adaptation of geospatial technologies such global positioning systems (GPS), yield monitors, autosteering, and the automated on-and-off technology required for site-specific nematicide application has provided growers with additional tools for managing nematodes. Multiple trials in several states were conducted to evaluate this technology in cotton. In a field infested with Meloidogyne spp., both shallow (0 to 0.3 m) and deep (0 to 0.91 m) apparent electrical conductivity (ECa) readings were highly correlated with sand content. Populations of Meloidogyne spp. were present when shallow and deep EC values were less than 30 and 90 mS/m, respectively. Across three years of trials in production fields in which verification strips (adjacent nematicide treated and untreated rows across all soil zones) were established to evaluate crop response to nematicide application, deep EC values from 27.4-m wide transects of verification strips were more predictive of yield response to application of 1,3-dichloropropene than were shallow EC values in one location and both ECa values equally effective at predicting responses at the second location. In 2006, yields from entire verification strips across three soil zones in four production fields showed that nematicide response was greatest in areas with the lowest EC values indicating highest content of sand. In 2008 in Ashley and Mississippi Counties, AR, nematicide treatment by soil zone resulted in 36% and 42% reductions in the amount of nematicide applied relative to whole-field application. In 2007 in Bamberg County, SC, there was a strong positive correlation between increasing population densities of Meloidogyne incognita and increasing sand content. Trials conducted during 2007 and 2009 in South Carolina against Hoplolaimus columbus showed a stepwise response to increasing rates of aldicarb in zone 1 but not in zones 2 and 3. Site-specific application of nematicides has been shown to be a viable option for producers as a potential management tool against several nematode pathogens of cotton.

Importance of Fungicide Seed Treatment and Environment on Seedling Diseases of Cotton.

The importance of fungicide seed treatments on cotton was examined using a series of standardized fungicide trials from 1993 to 2004. Fungicide seed treatments increased stands over those from seed not treated with fungicides in 119 of 211 trials. Metalaxyl increased stands compared to nontreated seed in 40 of 119 trials having significant fungicide responses, demonstrating the importance of Pythium spp. on stand establishment. Similarly, PCNB seed treatment increased stands compared to nontreated seed for 44 of 119 trials with a significant response, indicating the importance of Rhizoctonia solani in stand losses. Benefits from the use of newer seed treatment chemistries, azoxystrobin and triazoles, were demonstrated by comparison with a historic standard seed treatment, carboxin + PCNB + metalaxyl. Little to no stand improvement was found when minimal soil temperatures averaged 25°C the first 3 days after planting. Stand losses due to seedling pathogens increased dramatically as minimal soil temperatures decreased to 12°C and rainfall increased. The importance of Pythium increased dramatically as minimal soil temperature decreased and rainfall increased, while the importance of R. solani was not affected greatly by planting environment. These multi-year data support the widespread use of seed treatment fungicides for the control of the seedling disease complex on cotton.

Increased Occurrence of Target Spot of Soybean Caused by Corynespora cassiicola in the Southeastern United States.

Target spot of soybean (Glycine max (L.) Merr.) caused by Corynespora cassiicola (Berk. & Curt.), although found in most soybean-growing countries, is considered to be a disease of limited importance (1) and has never been reported to cause soybean yield loss in the southeastern United States (2,3). Soybean plants submitted to the North Carolina Plant Disease and Insect Clinic (NCPDIC) in August 2004 from Beaufort, Robeson, Wilson, and Johnston counties, NC had symptoms consistent with target spot. Symptoms consisted of roughly circular, necrotic leaf lesions from minute to 11 mm in diameter, though typically approximately 4 to 5 mm in diameter, and with a yellow margin. Large lesions occasionally exhibited a zonate pattern often associated with this disease. Microscopic examination of the lesions revealed the presence of spores (conidia) typical of C. cassiicola (1). Conidia were mostly three to five septate with a central hilum at the base and ranged in size from 7 to 22 wide × 39 to 520 µm long. Three commercial soybean fields near Blackville, SC (Barnwell County) were severely affected by this disease and it caused premature defoliation. Nineteen of twenty-seven maturity group VII and VIII genotypes in the 2004 Clemson University soybean variety trial near Blackville, SC had visible symptoms of target spot. Heavy rainfall associated with hurricanes during September 2004 probably enhanced the incidence of this disease, and yield suppression due to target spot was estimated at 20 to 40% in some fields. In 2005, 20 of 161 soybean samples submitted to the NCPDIC or collected in surveys from 16 counties were positive for target spot on the basis of microscopic examination. Target spot also was diagnosed in six counties (Baldwin, DeKalb, Elmore, Fayette, Macon, and Pickens) in Alabama and in four additional counties (Bamberg, Hampton, Orange-burg, and Calhoun) in South Carolina in 2005. Records from the NCPDIC indicate that target spot had not been diagnosed on soybean in North Carolina since 1981. The large increase in incidence of target spot in the southeast may be related to changes in weather patterns, changes in pathogen virulence, and/or the introduction of more susceptible host genotypes. References: (1) J. B. Sinclair. Target spot. Page 27 in: Compendium of Soybean Diseases. G. L. Hartman et al. eds. The American Phytopathological Society, St. Paul, MN, 1999. (2) J. A. Wrather et al. Plant Dis. 79:1076. 1995. (3) J. A. Wrather et al. On-line publication. doi:10.1094/PHP-2003-0325-01-RV. Plant Health Progress, 2003.

Chromosomal instability in flat adenomas and carcinomas of the colon.

Flat adenomas are flat or slightly elevated dysplastic lesions of the colorectal mucosa, mostly with a tubular architecture. Compared with polypoid adenomas of similar size, flat adenomas show a higher frequency of high-grade dysplasia and rapid submucosal invasion. The aim of this study was to survey whether flat colorectal lesions differ in their pattern of chromosomal aberrations from their polypoid counterparts. Six flat adenomas and 12 flat carcinomas were analysed by comparative genomic hybridization (CGH) and the pattern of chromosomal aberrations was compared with a previously published series of 112 polypoid adenomas and 82 polypoid carcinomas. In addition, multiplex ligation-dependent probe amplification (MLPA) for identifying DNA copy number changes of 25 individual genes on chromosome 20 was performed on 14 flat and 15 polypoid tumours. With CGH, flat adenomas showed on average 1.8 gains (range 1-4) and 3.2 losses (range 0-4), and the flat carcinomas 4.5 gains (range 0-8) and 3.5 losses (range 1-6). In both adenomas and carcinomas, high frequencies of 20q gain (83% and 92%, respectively) and 18q loss (83% and 92%, respectively) were found. This correlation between 20q gain and 18q loss had previously been observed in a subgroup of polypoid colorectal tumours. Both flat and polypoid colorectal tumours with 20q gains by CGH showed similar patterns of copy number ratios for the individual genes tested. TOP1, BCL2L1, and E2F1 had median copy number ratios of 2 or higher, while ZNF217 had a ratio around 3. In conclusion, flat adenomas and carcinomas of the large intestine show a similar pattern of chromosomal aberrations to that observed in a specific subgroup of polypoid lesions. The transcription factor ZNF217 is an important candidate for driving the 20q gain.

Progressive changes in adherens junction structure during intestinal adenoma formation in Apc mutant mice.

The C57BL/6J-Min/+ (Min/+) mouse bears a mutant Apc gene and therefore is an important in vivo model of intestinal tumorigenesis. Min/+ mice develop adenomas that exhibit loss of the wild-type Apc allele (Apc(Min/-)). Previously, we found that histologically normal enterocytes bearing a truncated Apc protein (Apc(Min/+)) migrated more slowly in vivo than enterocytes with either wild-type Apc (Apc(+/+)) or with heterozygous loss of Apc protein (Apc(1638N)). To study this phenotype further, we determined the effect of the Apc(Min) mutation upon cell-cell adhesion by examining the components of the adherens junction (AJ). We observed a reduced association between E-cadherin and beta-catenin in Apc(Min/+) enterocytes. Subcellular fractionation of proteins from Apc(+/+), Apc(Min/+), and Apc(Min/-) intestinal tissues revealed a cytoplasmic localization of intact E-cadherin only in Apc(Min/+), suggesting E-cadherin internalization in these enterocytes. beta-Catenin tyrosine phosphorylation was also increased in Apc(Min/+) enterocytes, consistent with its dissociation from E-cadherin. Furthermore, Apc(Min/+) enterocytes showed a decreased association between beta-catenin and receptor protein-tyrosine phosphatase beta/zeta (RPTPbeta/zeta), and Apc(Min/-) cells demonstrated an association between beta-catenin and receptor protein-tyrosine phosphatase gamma. In contrast to the Apc(Min/+) enterocytes, Apc(Min/-) adenomas displayed increased expression and association of E-cadherin, beta-catenin, and alpha-catenin relative to Apc(+/+) controls. These data show that Apc plays a role in regulating adherens junction structure and function in the intestine. In addition, discovery of these effects in initiated but histologically normal tissue (Apc(Min/+)) defines a pre-adenoma stage of tumorigenesis in the intestinal mucosa.

Assessing latex allergy among health care employees using workers' compensation data.

Latex allergies among health care workers have garnered considerable attention from medical researchers and practitioners. However, the majority of research on natural rubber latex allergy has focused on clinical methodologies and emphasized the quantification of employee sensitization rates as opposed to actual incidents of reactivity. Workers' compensation data provide information on the number and impact of reactions to latex use. This article presents an analysis of health care workers' compensation data from North Dakota to estimate the prevalence, costs, and nature of claims associated with latex allergic reaction. The results show an annual average claim rate of 1.52 per 10,000 health care workers employed in the state, and annual costs averaging about $.08 per health care worker. Skin disorders were the most commonly reported condition. These findings are compared with previous studies of Minnesota and Rhode Island and demonstrate similar results.

Frequency and clinical impact of lymph node micrometastasis and tumor cell microinvolvement in patients with adenocarcinoma of the esophagogastric junction.

BACKGROUND: Tumor involvement of regional lymph nodes has a crucial impact on the prognosis of patients with adenocarcinoma of the esophagogastric junction (AEG). Although additional tumor cell deposits can be detected by sensitive methods (e.g., immunohistochemistry and polymerase chain reaction), their prognostic significance is uncertain. METHODS: Using immunohistochemistry for cytokeratins (AE1/AE3 antibody), the authors studied 3987 regional lymph nodes from 145 patients with completely resected adenocarcinoma of the esophagus (AEG I; n = 46 patients), cardia (AEG II; n = 79 patients), and subcardial region (AEG III; n = 20 patients). The newly detected cells were categorized with tumor cell microinvolvement (TCM) or with micrometastases (MM) based on tumor size and histology. RESULTS: Of the 75 pathologic lymph node negative (pN0) patients, 3 of 30 patients in the AEG I group (10%) and 8 of 45 patients in the AEG II and III groups (18%) had TCM (no significant difference). MM was found in 2 of 30 tumors in the AEG I group (7%) and in 11 of 45 tumors in the AEG II and III groups (24%), a significantly lower rate that that in the AEG I group (P < 0.05). Neither TCM nor MM showed a significant prognostic impact in AEG I tumors (P > 0.05). For the AEG II and III tumors, MM (new lymph node positive [pN+] cases) had a prognostic impact similar to metastases found by routine methods, with reclassification based on MM resulting in improvement in the pN0 group from 72.8 months to 82.6 months, but almost no change was seen in the pN+ group (49.9-49.2 months). TCM had no adverse impact on survival in any tumor type. CONCLUSIONS: These results highlight important differences between AEG I tumors and AEG II and III tumors and argue for different lymphadenectomy strategies for patients with these tumor types.

Predictors and outcomes of proactivity in the socialization process.

This 3-wave longitudinal study aimed to extend current understanding of the predictors and outcomes of employee proactivity (involving information seeking, feedback seeking, relationship building, and positive framing) in the socialization process. Two personality variables, extraversion and openness to experience, were associated with higher levels of proactive socialization behavior. Of the proactive behaviors studied, feedback seeking and relationship building were highlighted in their importance because of their various relationships with the work-related outcomes assessed in this study (e.g., social integration, role clarity, job satisfaction, intention to turnover, and actual turnover). The results also highlighted the importance of 2 control variables (opportunity to interact with others on the job and skill level of the new job) in the experience of socialization into a new job.

Neoadjuvant chemotherapy for patients with locally advanced gastric carcinoma: effect on tumor cell microinvolvement of regional lymph nodes.

BACKGROUND: In a previous study the authors demonstrated, using immunohistochemical methods for epithelial antigens, that the regional lymph nodes of gastric adenocarcinoma contained individual tumor cells or small clusters of these cells (tumor cell microinvolvement [TCM]) in over 90% of cases. In the current study the authors used the same method to investigate a series of gastric adenocarcinoma cases treated with neoadjuvant chemotherapy prior to tumor resection; their aim was to determine the effect of chemotherapy on TCM in regional lymph nodes. METHODS: Resection specimens from 17 patients with adenocarcinoma of the stomach, resected after neoadjuvant treatment and classified by routine histology as ypN0, were included in this study. One section from each of the 622 lymph nodes dissected from these specimens was stained by immunohistochemical methods for cytokeratins and Ber-Ep4. RESULTS: Six patients (35%) and 25 of the 622 lymph nodes (4.0%) had TCM, compared with 93% of patients and 21.8% of lymph nodes in the previous study of patients treated with surgery alone. The lymph node response to chemotherapy correlated with the pathologic response of the primary tumor. Specifically, none of 5 patients with a complete or major pathologic response versus 6 of 12 (50%) patients with minor, partial, or no response had lymph node microinvolvement. CONCLUSIONS: In comparison to our previous study, this study indicates that chemotherapy has a marked effect on tumor cells in regional lymph nodes and that the extent of this effect can be correlated with the degree of pathologic response of the primary tumor to chemotherapy.

Immunocytochemically detected free peritoneal tumour cells (FPTC) are a strong prognostic factor in gastric carcinoma.

We prospectively investigated the prognostic significance of free peritoneal tumour cells (FPTC) in a series of 118 patients with completely resected gastric carcinoma. Immunocytochemistry with the monoclonal antibody Ber-Ep4 was performed on cytospins from intraoperative peritoneal lavage specimens. Twenty-three patients (20%) had FPTC which was significantly correlated with pT and pN categories, stage, tumour size, lymphatic invasion, Laurèn and WHO classifications and perigastric adipose tissue metastases. The median survival time for all FPTC positive compared with negative patients was significantly shorter (11 compared with >72 months), with estimated 5-year survival rates of 8% vs. 60%. None of the patients with FPTC had an early gastric cancer. In advanced tumour subgroups without and with serosal invasion (n = 59 and 35), there were 19% and 34% with FPTC. Multivariate survival analysis showed nodal status, FPTC, mesenteric lymphangiosis, and lymph node metastasis to the compartment III to be independent prognostic factors with relative risks of 6.6, 4.5, 2.9 and 2.2 respectively. Recurrent disease occurred in 91% of FPTC-positive and in 38% of FPTC-negative patients. FPTC had a positive predictive value of 91% and a specificity of 97% for tumour recurrence. FPTC is a strong negative, independent prognostic indicator for survival in gastric carcinoma.

Loss of heterozygosity and microsatellite instability in de novo versus ex-adenoma carcinomas of the colorectum.

Small adenocarcinomas of the colorectum showing no evidence of origin from an adenoma have been called de novo carcinomas, a name that implies an origin via a different molecular genetic mechanism than the usual colorectal carcinoma which develops from an adenoma. Using microsatellite analysis, 35 early (pT1) de novo and 36 pT1 ex-adenoma carcinomas were compared using 8 microsatellite loci at 6 different chromosomal loci (1p, 2p, 8p, 5q, 17p, and 18q) known or hypothesized to be important for colorectal carcinogenesis. The rate of loss of heterozygosity (LOH) at the 17p locus (near the p53 gene) was significantly higher in the de novo than in the ex-adenoma group (73 vs. 37%, P = 0.004). The rates of LOH at the other loci (including the APC and DCC genes) and the rate of MSI were not significantly different in the two groups. These results indicate that de novo carcinomas of the colorectum develop via a similar carcinogenetic pathway as conventional ex-adenoma carcinomas; however, their higher rate of LOH at 17p is evidence for a biologically more advanced lesion with more frequent p53 mutations, consistent with clinicopathological data indicating that de novo carcinomas are more aggressive than ex-adenoma carcinomas.

Comparison of CD44 expression in early colorectal carcinomas of the de novo and ex adenoma types.

Small colorectal carcinomas without morphological evidence of origin from an adenoma have been called "de novo" carcinomas. As changes in the expression of the adhesion molecule CD44 and its variants have been described along the adenoma-carcinoma sequence in colorectal carcinoma, we compared patterns of CD44 expression in early de novo and ex-adenoma colorectal carcinomas by staining specimens from a group of early (pT1) colorectal carcinomas by immunohistochemistry for CD44 (standard and variant forms v3, v5, v6, v7, v7/8, v10). We evaluated carcinoma, adenoma (ex-adenoma cases), transitional mucosal areas and apparently nonneoplastic mucosa peripheral to the lesions (when present). A marked increase was seen in numbers and intensity of standard and variant forms of CD44 in carcinomatous areas compared with nonneoplastic mucosa in both groups, with no significant difference between the groups. However, adenoma areas of the ex-adenoma cases and the transitional mucosa of the de novo carcinomas had nearly identical staining patterns. Together with data from other molecular studies, this may be interpreted as evidence for an adenoma-type precursor lesion in so-called de novo colorectal carcinomas.

Strong prognostic impact of tumor-associated urokinase-type plasminogen activator in completely resected adenocarcinoma of the esophagus.

The serine protease system has been shown to play an important role in the invasive potential of a variety of tumors. To date, however, there are little data about the expression of these proteases in esophageal carcinoma. To determine the level of expression and the significance of urokinase-type plasminogen activator (uPA) and its plasminogen activator inhibitor type 1 (PAI-1) in adenocarcinoma of the esophagus, we studied 54 tumor cases and a control group of normal gastric mucosa cases with ELISA using detergent-extracted samples. uPA and PAI-1 were significantly elevated as compared to control tissue by factors of 16 and 14, respectively. Median levels of both uPA and PAI-1 showed significant correlation with tumor pT, pN, and pM categories, whereas the presence of lymphatic invasion correlated only with the uPA content and tumor grade correlated only with PAI-1 content. Using maximally selected statistics, a cutoff value was found for uPA (2.85 ng/mg protein) but not for PAI-1, which divided the study group into significantly poorer and better survival subgroups. By univariate analysis, depth of tumor invasion (pT), lymph node involvement (pN), number of involved lymph nodes, lymph node ratio, distant nodal metastases [pM1(Iym)], lymphatic invasion, and uPA showed significant correlations with patient survival. By multivariate analysis, uPA (first rank), pN, and pM (lym) were identified as independent prognostic factors, with relative risks of 8.4, 4.1, and 4.3, respectively. In a second survival analysis method, a prognostic model was developed using classification and regression trees analysis, in which a significant difference among three patient survival groups was distinguished using the variables "number of involved lymph nodes" and "uPA content." In summary, tumor uPA content as determined by ELISA appears to be a powerful, independent prognostic factor for survival in adenocarcinoma of the esophagus.

Self-sustained sequence replication (3SR): an alternative to PCR.

The amplification of target nucleic acids before hybridization is one of the most powerful approaches for the detection of low copy number RNA and DNA. The best known amplification reaction is PCR which has many applications. However, certain drawbacks of the PCR reaction provide a role for alternative amplification methods. One of these methods is the self-sustained sequence replication (3SR) reaction, which is an isothermal method for RNA amplification depending on the action of three enzymes. 3SR has been used in several in vitro applications and has also been modified for in situ use (IS-3SR). We have studied IS-3SR with the measles virus as a model and have found that it can significantly amplify the amount of intracellular RNA. Such a level of amplification could raise the amount of single copy RNA to the level of detection by conventional in situ hybridization. Although careful controls to insure its specificity must be carried out, IS-3SR has several advantages, including ease of use, preserved cell morphology, and specificity for RNA amplification, which make it an attractive alternative to the in situ PCR method.

Effect of Planting Date on Population Densities of Hoplolaimus columbus and Yield of Soybean.

During the 1991 and 1992 soybean growing seasons, field plots were established in South Carolina to study the effect of planting date on at-planting nematode densities and subsequent yield losses caused by Hoplolaimus columbus. The susceptible and intolerant soybean cv. Braxton was planted on five dates from to May to 28 June in 1991 and from 12 May to 28 June in 1992. Nematodes were recovered from soil samples collected before nematicide treatment with 1,3-D (Pi), at 6 weeks after planting (Pm), and at harvest (Pf). Initial nematode population densities did not differ among the five dates of planting in either year. The increase in numbers of nematodes from planting to 6 weeks after planting (Pm/Pi) and from planting to harvest (Pf/Pi) were not different among the five planting dates in either year. Root samples also were collected at 6 weeks after planting and at harvest, but planting date did not affect the number of nematodes extracted from roots on any sample date in either year. Altering planting dates between early May and late June was not effective in preventing yield suppression due to H. columbus.

Standardization of reporting procedures for nematicide efficacy testing: a research and extension perspective.

Nematicide tests reported in the Annals of Applied Nematology from 1991 to 1995 were reviewed and evaluated for 24 criteria. Most criteria such as soil type, nematode density, cultivar planted, test location, and nematicide applied were reported in more than adequate detail. Soil moisture content and temperature conditions during the test, field history of pesticide use, agronomic-horticultural production practices, and measurements of yield were reported less adequately. Many reports dealing with fumigant nematicides and application by irrigation had inadequate descriptions of rates and application methodology, Although areas for improvement exist, overall the published works in Annals of Applied Nematology are well-reported experiments. Pressure exists from several elements of hematology to "standarize" reporting procedures and test practices. Due to the diversity of crops, nematodes, nematicides, edaphic and environmental conditions that affect nematicide fate, nematode activity, plant growth, and subsequently nematicide efficacy, creation of a completely standardized format is improbable. More accurate reporting of some test criteria rather than standardization will allow better comparison between tests when results do not concur and allow future researchers to duplicate application rates and methodologies to determine the sources of discrepancies between tests, including environmental variations.

In situ amplification of measles virus RNA by the self-sustained sequence replication reaction.

BACKGROUND: The self-sustained sequence replication (3SR) reaction is an isothermal method for nucleic acid amplification that has several features that make it an attractive alternative to PCR. We have studied the feasibility of the in situ 3SR reaction in cells using a measles virus-infected cell line as a model. EXPERIMENTAL DESIGN: The study was carried out in four steps. First, using RNA extracted from a measles-infected Vero Green monkey kidney cell line, conditions for the in vitro amplification of a segment of the nucleocapsid portion of the RNA viral genome were optimized for 420- and 119-bp 3SR products, and the results were compared. Second, 3SR was performed on intact infected cells in suspension, and the amount of RNA product was compared with infected cells without 3SR. Then, the 3SR reaction was conducted on cytospin preparation slides, followed by in situ hybridization for detection of the amplification product. Finally, 3SR was carried out on sections of formalin-fixed, paraffin-fixed, paraffin-embedded cells, and the degree of amplification as detected by ISH was quantified and compared between infected cells with and without 3SR reaction. RESULTS: Specific amplification of measles was observed in each of these types of preparations with an 8.5-fold rate of amplification in paraffin sections of formalin-fixed cells (a mean of 272.5 +/- 65.3 grains/cell after 3SR amplification in comparison to 31.97 +/- 4.2 grains/cell without amplification). CONCLUSIONS: A significant amount of amplification of RNA is possible with in situ 3SR (IS-3SR) and, in combination with ISH, offers several advantages compared with in situ PCR (IS-PCR), such as ease of use, lack of conditions that lead to cell damage, and a specificity for RNA amplification. This is the first report of specific amplification of RNA within cells using the IS-3SR procedure, a technique that has a wide range of potential applications in pathology and molecular biology.

N2 lung cancer: outcome in patients with false-negative computed tomographic scans of the chest.

Over the past 13 years 681 consecutive patients have undergone computed tomographic staging and surgical staging of the mediastinum. Five hundred one tested negative for mediastinal lymph node enlargement by computed tomographic staging, and 37 of these patients had cancerous mediastinal lymph nodes at thoracotomy (n = 36) or mediastinoscopy (n = 1). The survival in this group of patients was analyzed according to T status, central or peripheral location of tumor, cell type, areas of mediastinum that are involved, and extent of nodal involvement with tumor. Twelve patients had central tumors, and 25 had peripheral tumors. Two of the patients in the central tumor group died postoperatively and only 2 others survived, whereas 12 of the 25 patients in the peripheral tumor group survived. Four of the 37 patients, 2 in each group, did not undergo resection, and all died. All but 2 of the 31 survivors who underwent resection received postoperative adjuvant x-ray therapy (23 patients), chemotherapy (1 patient), or x-ray therapy and chemotherapy (5 patients). The projected 2-year and 5-year survivals (Kaplan-Meier) were 40% and 28% for patients overall, 46% and 31% for those whose tumors were resected, 40% and 20% for those with resected central tumors, and 52% and 45% for those with resected peripheral tumors. None of these differences was significant. Cell type, location or number of locations of involved nodes, and the average percentage or maximum percentage of mediastinal node that was involved with tumor did not influence survival. The high negative predictive index for computed tomographic staging of the mediastinal lymph nodes and the observed 2-year and 5-year survivals in patients with false-negative computed tomographic scans of the chest justifies definitive thoracotomy without mediastinoscopy in most patients with a normal mediastinum on computed tomographic scan.