The influence of anastomotic techniques on postoperative anastomotic complications: Results of the Oesophago-Gastric Anastomosis Audit

BACKGROUND

The optimal anastomotic techniques in esophagectomy to minimize rates of anastomotic leakage and conduit necrosis are not known. The aim of this study was to assess whether the anastomotic technique was associated with anastomotic failure after esophagectomy in the international Oesophago-Gastric Anastomosis Audit cohort.

METHODS

This prospective observational multicenter cohort study included patients undergoing esophagectomy for esophageal cancer over 9 months during 2018. The primary exposure was the anastomotic technique, classified as handsewn, linear stapled, or circular stapled. The primary outcome was anastomotic failure, namely a composite of anastomotic leakage and conduit necrosis, as defined by the Esophageal Complications Consensus Group. Multivariable logistic regression modeling was used to identify the association between anastomotic techniques and anastomotic failure, after adjustment for confounders.

RESULTS

Of the 2238 esophagectomies, the anastomosis was handsewn in 27.1%, linear stapled in 21.0%, and circular stapled in 51.9%. Anastomotic techniques differed significantly by the anastomosis sites (P < .001), with the majority of neck anastomoses being handsewn (69.9%), whereas most chest anastomoses were stapled (66.3% circular stapled and 19.3% linear stapled). Rates of anastomotic failure differed significantly among the anastomotic techniques (P < .001), from 19.3% in handsewn anastomoses, to 14.0% in linear stapled anastomoses, and 12.1% in circular stapled anastomoses. This effect remained significant after adjustment for confounding factors on multivariable analysis, with an odds ratio of 0.63 (95% CI, 0.46-0.86; P = .004) for circular stapled versus handsewn anastomosis. However, subgroup analysis by anastomosis site suggested that this effect was predominantly present in neck anastomoses, with anastomotic failure rates of 23.2% versus 14.6% versus 5.9% for handsewn versus linear stapled anastomoses versus circular stapled neck anastomoses, compared with 13.7% versus 13.8% versus 12.2% for chest anastomoses.

CONCLUSIONS

Handsewn anastomoses appear to be independently associated with higher rates of anastomotic failure compared with stapled anastomoses. However, this effect seems to be largely confined to neck anastomoses, with minimal differences between techniques observed for chest anastomoses. Further research into standardization of anastomotic approach and techniques may further improve outcomes.

Textbook outcome following oesophagectomy for cancer: international cohort study

Background

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

Methods

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

Results

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter ‘no major postoperative complication’ had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P &lt; 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P &lt; 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

Conclusion

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Textbook outcome following oesophagectomy for cancer: international cohort study

BACKGROUND

Textbook outcome has been proposed as a tool for the assessment of oncological surgical care. However, an international assessment in patients undergoing oesophagectomy for oesophageal cancer has not been reported. This study aimed to assess textbook outcome in an international setting.

METHODS

Patients undergoing curative resection for oesophageal cancer were identified from the international Oesophagogastric Anastomosis Audit (OGAA) from April 2018 to December 2018. Textbook outcome was defined as the percentage of patients who underwent a complete tumour resection with at least 15 lymph nodes in the resected specimen and an uneventful postoperative course, without hospital readmission. A multivariable binary logistic regression model was used to identify factors independently associated with textbook outcome, and results are presented as odds ratio (OR) and 95 per cent confidence intervals (95 per cent c.i.).

RESULTS

Of 2159 patients with oesophageal cancer, 39.7 per cent achieved a textbook outcome. The outcome parameter 'no major postoperative complication' had the greatest negative impact on a textbook outcome for patients with oesophageal cancer, compared to other textbook outcome parameters. Multivariable analysis identified male gender and increasing Charlson comorbidity index with a significantly lower likelihood of textbook outcome. Presence of 24-hour on-call rota for oesophageal surgeons (OR 2.05, 95 per cent c.i. 1.30 to 3.22; P = 0.002) and radiology (OR 1.54, 95 per cent c.i. 1.05 to 2.24; P = 0.027), total minimally invasive oesophagectomies (OR 1.63, 95 per cent c.i. 1.27 to 2.08; P < 0.001), and chest anastomosis above azygous (OR 2.17, 95 per cent c.i. 1.58 to 2.98; P < 0.001) were independently associated with a significantly increased likelihood of textbook outcome.

CONCLUSION

Textbook outcome is achieved in less than 40 per cent of patients having oesophagectomy for cancer. Improvements in centralization, hospital resources, access to minimal access surgery, and adoption of newer techniques for improving lymph node yield could improve textbook outcome.

Postoperative outcomes in oesophagectomy with trainee involvement

BACKGROUND

The complexity of oesophageal surgery and the significant risk of morbidity necessitates that oesophagectomy is predominantly performed by a consultant surgeon, or a senior trainee under their supervision. The aim of this study was to determine the impact of trainee involvement in oesophagectomy on postoperative outcomes in an international multicentre setting.

METHODS

Data from the multicentre Oesophago-Gastric Anastomosis Study Group (OGAA) cohort study were analysed, which comprised prospectively collected data from patients undergoing oesophagectomy for oesophageal cancer between April 2018 and December 2018. Procedures were grouped by the level of trainee involvement, and univariable and multivariable analyses were performed to compare patient outcomes across groups.

RESULTS

Of 2232 oesophagectomies from 137 centres in 41 countries, trainees were involved in 29.1 per cent of them (n = 650), performing only the abdominal phase in 230, only the chest and/or neck phases in 130, and all phases in 315 procedures. For procedures with a chest anastomosis, those with trainee involvement had similar 90-day mortality, complication and reoperation rates to consultant-performed oesophagectomies (P = 0.451, P = 0.318, and P = 0.382, respectively), while anastomotic leak rates were significantly lower in the trainee groups (P = 0.030). Procedures with a neck anastomosis had equivalent complication, anastomotic leak, and reoperation rates (P = 0.150, P = 0.430, and P = 0.632, respectively) in trainee-involved versus consultant-performed oesophagectomies, with significantly lower 90-day mortality in the trainee groups (P = 0.005).

CONCLUSION

Trainee involvement was not found to be associated with significantly inferior postoperative outcomes for selected patients undergoing oesophagectomy. The results support continued supervised trainee involvement in oesophageal cancer surgery.

Mortality from esophagectomy for esophageal cancer across low, middle, and high-income countries: An international cohort study

BACKGROUND

No evidence currently exists characterising global outcomes following major cancer surgery, including esophageal cancer. Therefore, this study aimed to characterise impact of high income countries (HIC) versus low and middle income countries (LMIC) on the outcomes following esophagectomy for esophageal cancer.

METHOD

This international multi-center prospective study across 137 hospitals in 41 countries included patients who underwent an esophagectomy for esophageal cancer, with 90-day follow-up. The main explanatory variable was country income, defined according to the World Bank Data classification. The primary outcome was 90-day postoperative mortality, and secondary outcomes were composite leaks (anastomotic leak or conduit necrosis) and major complications (Clavien-Dindo Grade III - V). Multivariable generalized estimating equation models were used to produce adjusted odds ratios (ORs) and 95% confidence intervals (CI95%).

RESULTS

Between April 2018 to December 2018, 2247 patients were included. Patients from HIC were more significantly older, with higher ASA grade, and more advanced tumors. Patients from LMIC had almost three-fold increase in 90-day mortality, compared to HIC (9.4% vs 3.7%, p < 0.001). On adjusted analysis, LMIC were independently associated with higher 90-day mortality (OR: 2.31, CI95%: 1.17-4.55, p = 0.015). However, LMIC were not independently associated with higher rates of anastomotic leaks (OR: 1.06, CI95%: 0.57-1.99, p = 0.9) or major complications (OR: 0.85, CI95%: 0.54-1.32, p = 0.5), compared to HIC.

CONCLUSION

Resections in LMIC were independently associated with higher 90-day postoperative mortality, likely reflecting a failure to rescue of these patients following esophagectomy, despite similar composite anastomotic leaks and major complication rates to HIC. These findings warrant further research, to identify potential issues and solutions to improve global outcomes following esophagectomy for cancer.

Comparison of short-term outcomes from the International Oesophago-Gastric Anastomosis Audit (OGAA), the Esophagectomy Complications Consensus Group (ECCG), and the Dutch Upper Gastrointestinal Cancer Audit (DUCA)

BACKGROUND

The Esophagectomy Complications Consensus Group (ECCG) and the Dutch Upper Gastrointestinal Cancer Audit (DUCA) have set standards in reporting outcomes after oesophagectomy. Reporting outcomes from selected high-volume centres or centralized national cancer programmes may not, however, be reflective of the true global prevalence of complications. This study aimed to compare complication rates after oesophagectomy from these existing sources with those of an unselected international cohort from the Oesophago-Gastric Anastomosis Audit (OGAA).

METHODS

The OGAA was a prospective multicentre cohort study coordinated by the West Midlands Research Collaborative, and included patients undergoing oesophagectomy for oesophageal cancer between April and December 2018, with 90 days of follow-up.

RESULTS

The OGAA study included 2247 oesophagectomies across 137 hospitals in 41 countries. Comparisons with the ECCG and DUCA found differences in baseline demographics between the three cohorts, including age, ASA grade, and rates of chronic pulmonary disease. The OGAA had the lowest rates of neoadjuvant treatment (OGAA 75.1 per cent, ECCG 78.9 per cent, DUCA 93.5 per cent; P < 0.001). DUCA exhibited the highest rates of minimally invasive surgery (OGAA 57.2 per cent, ECCG 47.9 per cent, DUCA 85.8 per cent; P < 0.001). Overall complication rates were similar in the three cohorts (OGAA 63.6 per cent, ECCG 59.0 per cent, DUCA 62.2 per cent), with no statistically significant difference in Clavien-Dindo grades (P = 0.752). However, a significant difference in 30-day mortality was observed, with DUCA reporting the lowest rate (OGAA 3.2 per cent, ECCG 2.4 per cent, DUCA 1.7 per cent; P = 0.013).

CONCLUSION

Despite differences in rates of co-morbidities, oncological treatment strategies, and access to minimal-access surgery, overall complication rates were similar in the three cohorts.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Noninvasive genomic detection of melanoma

BACKGROUND

Early detection and treatment of melanoma is important for optimal clinical outcome, leading to biopsy of pigmented lesions deemed suspicious for the disease. The vast majority of such lesions are benign. Thus, a more objective and accurate means for detection of melanoma is needed to identify lesions for excision.

OBJECTIVES

To provide proof-of-principle that epidermal genetic information retrieval (EGIR™; DermTech International, La Jolla, CA, U.S.A.), a method that noninvasively samples cells from stratum corneum by means of adhesive tape stripping, can be used to discern melanomas from naevi.

METHODS

Skin overlying pigmented lesions clinically suspicious for melanoma was harvested using EGIR. RNA isolated from the tapes was amplified and gene expression profiled. All lesions were removed for histopathological evaluation.

RESULTS

Supervised analysis of the microarray data identified 312 genes differentially expressed between melanomas, naevi and normal skin specimens (P<0·001, false discovery rate q<0·05). Surprisingly, many of these genes are known to have a role in melanocyte development and physiology, melanoma, cancer, and cell growth control. Subsequent class prediction modelling of a training dataset, consisting of 37 melanomas and 37 naevi, discovered a 17-gene classifier that discriminates these skin lesions. Upon testing with an independent dataset, this classifier discerned in situ and invasive melanomas from naevi with 100% sensitivity and 88% specificity, with an area under the curve for the receiver operating characteristic of 0·955.

CONCLUSIONS

These results demonstrate that EGIR-harvested specimens can be used to detect melanoma accurately by means of a 17-gene genomic biomarker.

Susceptibility to Coccidioides species in C57BL/6 mice is associated with expression of a truncated splice variant of Dectin-1 (Clec7a)

Coccidioides posadasii spherules stimulate macrophages to make cytokines via TLR-2 and Dectin-1. We used formalin-killed spherules and 1,3-beta-glucan purified from spherules to stimulate elicited peritoneal macrophages and myeloid dendritic cells (mDCs) from susceptible (C57BL/6) and resistant (DBA/2) mouse strains. DBA/2 macrophages produced more TNF-alpha and IL-6 than macrophages from C57BL/6 mice, and the amount of TNF-alpha made was dependent on both TLR2 and Dectin-1. DCs from C57BL/6 mice made more IL-10 and less IL-23p19 and IL-12p70 than did DBA/2 DC. These responses were inhibited by a monoclonal antibody to Dectin-1. DBA/2 mice expressed full-length Dectin-1, whereas C57BL/6 mice spliced out exon 3, which encodes most of the stalk. RAW cells transduced to express the full-length Dectin-1 responded better to FKS than cells expressing truncated Dectin-1. We compared the isoform of Dectin-1 expressed by 34 C57BL/6 X DBA/2 recombinant inbred (BXD RI) lines with their susceptibility to Coccidioides immitis. In 25 of 34 RI lines susceptibility or resistance corresponded to short or full-length isoforms, respectively. These results suggest that alternative splicing of the Dectin-1 gene contributes to susceptibility of C57BL/6 mice to coccidioidomycosis, and affects the cytokine responses of macrophages and mDCs to spherules.

Acetaminophen-induced hepatic failure with encephalopathy in a newborn

We report a case of oral acetaminophen toxicity in a term newborn infant successfully treated with a 20 h intravenous N-acetylcysteine infusion protocol without any adverse effects. This case report supports the use of N-acetylcysteine to treat neonatal acetaminophen toxicity and highlights the need for better education of parents regarding the appropriate use and dosage of acetaminophen in newborns.

Genetic evidence for the role of the Lv locus in early susceptibility but not IL-10 synthesis in experimental coccidioidomycosis in C57BL mice

Loci on chromosome 4 near Lv and on chromosome 6 near Tnfr1 are associated with resistance to coccidioidomycosis in mice. To assess the importance of the Lv locus, we compared C57BL/6 (B6) with C57BL/10 (B10), strains that are nearly congenic for the Lv locus. Fourteen days after intraperitoneal infection, B6 mice had nearly 100-fold more Coccidioides immitis in their lungs than did B10 mice (log 6.2 vs. log 4.8). Furthermore, the time to 50% deaths was 15 days for B6 and 22 days for B10. Nevertheless, 90% of B10 mice had died by day 28. In other mouse strains, we found a direct correlation between lung colony-forming units and levels of interleukin (IL)-10 and IL-4 mRNA, but B10 mice had 100-fold higher lung levels of IL-10 and 10-fold higher levels of IL-4 mRNA than did B6 mice, despite having less C. immitis. In the absence of IL-10, B10 mice are resistant to lethal infection. These results suggest that a locus near Lv is responsible for early resistance to coccidioidomycosis but not for modulating the IL-10 and IL-4 responses. This locus is not sufficient to make C57BL mice resistant to coccidioidomycosis.

Genes influencing resistance to Coccidioides immitis and the interleukin-10 response map to chromosomes 4 and 6 in mice

Coccidioidomycosis is a fungal infection that is endemic in the southwestern United States. Infection is more severe in blacks and Filipinos, which suggests that there is a genetic basis for susceptibility to this infection in humans. We found that there is also a difference in resistance to Coccidioides immitis infection among inbred mouse strains: B6 mice are susceptible, while DBA/2 mice are resistant (T. N. Kirkland and J. Fierer, Infect. Immun. 40:912-916, 1983). In this paper we report the results of our efforts to map the genes responsible for resistance to this infection in mice. Mice were infected by intraperitoneal inoculation, and 15 days later the numbers of viable fungi in their lungs and spleens were enumerated. We also determined the amounts of interleukin-10 mRNA made in the infected lungs. These three phenotypes were mapped as quantitative traits by using the 26 available lines of recombinant inbred mice derived from a cross between B6 and DBA/2 mice. The best associations were those between the regions near the Lv locus on chromosome 4 and the Tnfr1 locus on chromosome 6. We then infected backcross mice [(B6 x DBA/2) x B6] and confirmed these associations; 14 of 16 (87%) mice that were heterozygous at both Lv and Tnfr1 were resistant to infection, whereas only 4 of 16 (25%) mice that were homozygous B6 at both loci were resistant. These are the first genetic loci to be associated with susceptibility to C. immitis, but there may be additional genes involved in murine resistance to this infection.

Importance of interleukin-10 in genetic susceptibility of mice to Coccidioides immitis

Inbred strains of mice vary in their susceptibility to Coccidioides immitis. We infected resistant DBA/2 (D2) mice and three susceptible strains of mice (C57BL/6 [B6], BALB/c, and CAST/Ei) by intraperitoneal injection of arthroconidia and determined the severity of infection based on colony counts of fungus in the spleens and lungs 14 days after infection. We used quantitative reverse transcription-PCR to measure the amounts of cytokines made in the spleens and lungs of infected mice. Susceptible mice made 1, 000-fold more interleukin-10 (IL-10) than resistant D2 mice and about 10-fold more IL-4. In contrast, D2 mice had more IL-12 p40 in their lungs than did B6 mice. Resistant and susceptible mice made equivalent amounts of gamma interferon, IL-6, and IL-2. In order to determine whether IL-10 adversely affected the response to C. immitis, we infected IL-10-deficient mice, and they were found to be as resistant as D2 mice. This result indicates that IL-10 plays a crucial role in determining susceptibility to C. immitis in inbred mice. Because IL-4 mRNA levels were higher in most strains of susceptible mice, we also infected IL-4-deficient B6 mice. They were more resistant than B6 controls but not as resistant as IL-10-deficient mice. Thus, both IL-10 and IL-4 adversely affect the ability of C57BL mice to resist infection with C. immitis, but IL-10 has a larger effect and is the cytokine that is consistently associated with susceptibility in all strains of inbred mice.

Generation of Chinese hamster ovary cell glycosylation mutants by retroviral insertional mutagenesis. Integration into a discrete locus generates mutants expressing high levels of N-glycolylneuraminic acid

Retroviral insertional mutagenesis can both generate somatic cell mutants and pinpoint the genomic locus associated with a mutant phenotype. In the present study, this approach was applied to Chinese hamster ovary cells (CHO) made susceptible to Moloney murine leukemia virus (MoMuLV) infection by stable expression of an ecotropic retrovirus receptor. These CHO cells were infected with a replication incompetent MoMuLV construct with a promoterless hygromycin phosphotransferase (hygro) gene inserted into the U3 region of the long terminal repeat and a second selectable marker, neomycin phosphotransferase (neo), expressed from an internal promoter. CHO clones containing integrated proviruses were selected with hygromycin or G418, and the subset of these with reduced cell surface Neu5Ac were then selected with wheat germ agglutinin (WGA). The majority of the resulting clones had a phenotype not previously described for WGA-resistant CHO mutants arising spontaneously or from chemical mutagenesis: Neu5Ac was almost completely replaced by Neu5Gc. We have provisionally termed these clones SAP mutants, for sialic acid phenotype. Southern analysis of HindIII digested DNA from four SAP mutants revealed that the MoMuLV provirus is present in a 10.4-kilobase (kb) fragment. Probing with a flanking CHO sequence resulted in equivalent hybridization to a 4.6-kb fragment and the 10.4-kb provirus-containing fragment in all four cases, while uninfected parental cells and non-SAP glycosylation mutants generated in the same retrovirus insertional mutagenesis experiments yielded only the 4.6-kb fragment. Sequencing of the 3'-flanking DNA revealed that each of the four SAP mutants had a unique provirus integration site falling within a 796 bp region of the CHO genome. The frequency with which SAP mutants arise suggests that this may be a preferred site for retrovirus integration.

AIDS-related behavioral research and nursing

As efforts targeted at producing an effective vaccine or a definitive cure are still in early stages of development, health education and prevention continue to be this country's major line of defense against acquired immunodeficiency syndrome (AIDS). This defense is dependent on knowledge of behaviors that place individuals at risk of human immunodeficiency virus (HIV) exposure and disease progression. This article reviews the critical points in our state of knowledge and offers additional areas of need. Research is needed to determine a database of persons who use psychoactive substances and to understand the HIV-associated behaviors linked to drug use. Epidemiologic studies are necessary to appreciate the sexual, contraceptive, and childbearing practices of users of any psychoactive substance. Greater emphasis also is needed to investigate the inherent effects of various psychoactive substances on the immune, neurologic, and endocrine systems. While biomedical research continues, it is apparent that research from behavioral studies are crucial to education and prevention efforts. Nurse investigators are well-positioned to play an important role in accumulating this information. Given the critical role of drug abuse in the HIV epidemic, the public health significance cannot be overestimated.

Isolation of novel complementary DNA clones from T lymphoma cells: one encodes a putative multiple membrane-spanning protein

Five novel complementary DNA (cDNA) clones which are differentially expressed between two closely related T lymphoma cell clones were isolated using subtraction-enriched differential screening. SL12.4 cells, from which the cDNAs were isolated, have characteristics of thymocytes at an intermediate stage in development and cause prominent extranodal ovarian tumors in syngeneic animals. A sister cell clone, SL12.3, derived from the same tumor, has a distinct phenotype and causes more aggressive, diffuse lymphomas. Four of the five novel genes are expressed in normal thymus, activated spleen cells, or gut-associated lymphoid tissue. The DNA sequence and predicted protein sequence are presented for one of the novel cDNA clones. This novel cDNA clone detects mRNA in normal thymus, gut-associated lymphoid tissue, and ovarian tissue. The predicted protein has four putative transmembrane-spanning regions. The expression of the transcript is repressed in somatic cell hybrids formed from SL12.4 cells fused with three different T lymphoma cell lines which lack detectable mRNA complementary to the novel cDNA clone. This trans-negative regulation suggests that the expression of the gene is regulated by repressional mechanisms.

Interaction of host cell proteins with the human T-cell leukemia virus type I transcriptional control region. II. A comprehensive map of protein-binding sites facilitates construction of a simple chimeric promoter responsive to the viral tax2 gene product

We present a map describing the binding of cellular proteins to a 300-base pair (bp) region of the human T-cell leukemia virus type I (HTLV-I) long terminal repeat. The map accounts for nearly all of the DNase I protection reported in a previous study using crude nuclear extracts. Notable features include a complex arrangement of overlapping binding sites encompassing the 21-bp repeat elements (see accompanying paper) as well as binding sites for the transcription factors Sp1 and NF-I that significantly deviate from the previously defined consensus recognition sequences. Based on the binding results, we constructed simple chimeric promoters containing 21-bp repeat elements, Sp1-, and nuclear factor I-binding sites upstream of a TATA box. Transient transfection experiments show that these promoters are expressed in T-cells and are regulated by the viral tax2 gene product. Deletion of the Sp1 and nuclear factor I sites abolishes tax-induction, suggesting that one or both of these proteins play a role in mediating the tax-responsiveness conferred by the 21-bp repeat element.