Vogt-Koyanagi-Harada disease developed during chemotherapy for Hodgkin lymphoma: a case report.

BACKGROUND: Ocular manifestations are known for non-Hodgkin lymphoma, but are rare for Hodgkin lymphoma. We report a case of Vogt-Koyanagi-Harada (VKH) disease presenting as serous retinal detachment and uveitis in both eyes in a child undergoing chemotherapy for Hodgkin lymphoma. CASE PRESENTATION: The patient was a 7-year-old boy with stage IIB Hodgkin lymphoma (nodular lymphocyte predominant type) who was undergoing chemotherapy, including 2 cycles of the OEPA regimen and 1 cycle of the COPDAC regimen. Two days after the end of the COPDAC regimen, the patient complained of headache and of blurred and decreased vision in both eyes. On the basis of optic symptoms, such as uveitis and serous retinal detachment in both eyes, increased cell counts in cerebrospinal fluid, and positivity for human leukocyte antigen (HLA)-DR4 in peripheral blood cells, incomplete VKH disease was diagnosed. Intravenous treatment with high-dose prednisolone (60mg/m2/day) for 7 days improved both visual acuity and serous retinal detachment and enabled the remains of the COPDAC chemotherapy cycle to be administered. With prednisolone treatment, visual acuity improved from 20/500 to 20/20 in the right eye and from 20/63 to 20/25 in the left eye. Because multiple vitiligo lesions later appeared in the abdomen, complete VKH disease was finally diagnosed. CONCLUSION: The onset of VKH disease occurred during chemotherapy for Hodgkin lymphoma. The patient was HLA-DR4-positive and might have had a predisposition to develop autoimmune diseases, including VKH disease. However, the anticancer drugs administered to this patient have not been reported to cause uveitis. Whether Hodgkin lymphoma triggered the development of VKH remains unclear. Early diagnosis of VKH disease and prompt treatment with high-dose prednisone enabled the patient to maintain good visual function despite chemotherapy for Hodgkin lymphoma.

In Vitro and In Vivo Antidiabetic Effects of Acidic Polysaccharides Extracted from Seaweeds.

We evaluated the α-glucosidase inhibitory activity of acidic polysaccharides (APs) extracted from seaweeds in vitro and their antidiabetic effects in KK-Ay mice. The α-glucosidase inhibitory activity of APs was differed among various seaweed species. Some APs showed higher inhibitory activity in the high-molecular-weight range, whereas others showed higher inhibitory activity in the low-molecular-weight range. Mice were fed low-molecular-weight APs from hijiki (LMWAPsH), which showed higher α-glucosidase inhibitory activity. Fasting blood glucose and HbA1c levels were significantly lower in the LMWAPsH group than in the control group (p<0.01). The calculated homeostasis model assessment-insulin resistance in the LMWAPsH group was significantly lower than that in the control group (p<0.05). These results suggest that α-glucosidase inhibitory activity differ among APs from different seaweed species, and each have an optimum molecular-weight range, and that LMWAPsH prevents the hyperglycemia in KK-Ay mice.

An in vitro carcinogenesis model for cervical cancer harboring episomal form of HPV16.

Deregulated expression of viral E6 and E7 genes often caused by viral genome integration of high-risk human papillomaviruses (HR-HPVs) into host DNA and additional host genetic alterations are thought to be required for the development of cervical cancer. However, approximately 15% of invasive cervical cancer specimens contain only episomal HPV genomes. In this study, we investigated the tumorigenic potential of human cervical keratinocytes harboring only the episomal form of HPV16 (HCK1T/16epi). We found that the HPV16 episomal form is sufficient for promoting cell proliferation and colony formation of parental HCK1T cells. Ectopic expression of host oncogenes, MYC and PIK3CAE545K, enhanced clonogenic growth of both early- and late-passage HCK1T/16epi cells, but conferred tumor-initiating ability only to late-passage HCK1T/16epi cells. Interestingly, the expression levels of E6 and E7 were rather lower in late-passage than in early-passage cells. Moreover, additional introduction of a constitutively active MEK1 (MEK1DD) and/or KRASG12V into HCK1T/16epi cells resulted in generation of highly potent tumor-initiating cells. Thus an in vitro model for progression of cervical neoplasia with episomal HPV16 was established. In the model, constitutively active mutation of PIK3CA, PIK3CAE545K, and overexpression of MYC, in the cells with episomal HPV16 genome were not sufficient, but an additional event such as activation of the RAS-MEK pathway was required for progression to tumorigenicity.

[Exploratory Study of the Risk Factors for Acute Kidney Injury in the Cisplatin Combination Chemotherapy for Solid Cancer].

In the present study, we investigated the rate of cisplatin(CDDP)-induced acute kidney injury(CIA)and examined its association with various clinical factors in the combination therapy with CDDP for solid cancers. A total of 726 cases of solid cancer that had been indicated for the CDDP combination regimen from December 2012 to December 2013 were enrolled. CIA occurred in 48 cases(6.6%). The multivariate analysis revealed that diabetes, the regular use of non-steroidal anti- inflammatory drugs(NSAIDs), first dose of CDDP, and severe hyponatremia(≥Grade 3)within one week after CDDP administration were significantly associated with an increased risk for CIA, whereas magnesium supplementation was associated with a significantly reduced risk for CIA. Particularly, diabetes and cardiovascular disease were identified as risk factors for CIA in patients with esophageal and head and neck cancers. Based on the results of this survey, it is important to formulate preventive measures, evaluate risk factors, and respond rapidly.

Clinical guidelines for the diagnosis and treatment of lower urinary tract dysfunction in patients with spinal cord injury.

The present article is an abridged English translation of the Japanese clinical guidelines for the diagnosis and treatment of lower urinary tract dysfunction in patients with spinal cord injury updated as of July 2019. The patients are adult spinal cord injured patients with lower urinary tract dysfunction; special consideration of pediatric and elderly populations is presented separately. The target audience is healthcare providers who are engaged in the medical care of patients with spinal cord injury. The mandatory assessment includes medical history, physical examination, frequency-volume chart, urinalysis, blood chemistry, transabdominal ultrasonography, measurement of post-void residual urine, uroflowmetry and video-urodynamic study. Optional assessments include questionnaires on the quality of life, renal scintigraphy and cystourethroscopy. The presence or absence of risk factors for renal damage and symptomatic urinary tract infection affects urinary management, as well as pharmacological treatments. Further treatment is recommended if the maximum conservative treatment fails to improve or prevent renal damage and symptomatic urinary tract infection. In addition, management of urinary incontinence should be considered individually in patients with risk factors for urinary incontinence and decreased quality of life.

An Ex-Vivo Culture System of Ovarian Cancer Faithfully Recapitulating the Pathological Features of Primary Tumors.

The success rate of establishing human cancer cell lines is not satisfactory and the established cell lines often do not preserve the molecular and histological features of the original tissues. In this study, we developed a novel culture method which can support proliferation of almost all primary epithelial ovarian cancer cells, as well as primary normal human oviductal epithelial cells. Cancer cells from fresh or frozen specimens were enriched by the anti-EpCAM antibody-conjugated magnetic beads, plated on Matrigel-coated plate and cultivated under the optimized culture conditions. Seventeen newly established ovarian cancer cell lines, which included all four major histotypes of ovarian cancer, were confirmed to express histotype-specific markers in vitro. Some of the cell lines from all the four histotypes, except mucinous type, generated tumors in immune-deficient mice and the xenograft tumor tissues recapitulated the corresponding original tissues faithfully. Furthermore, with poorly tumorigenic cell lines including mucinous type, we developed a novel xenograft model which could reconstruct the original tissue architecture through forced expression of a set of oncogenes followed by its silencing. With combination of the novel culture method and cell-derived xenograft system, virtually every epithelial ovarian cancer can be reconstituted in mice in a timely fashion.

Effects of Surgery With Salvage Stereotactic Radiosurgery Versus Surgery With Whole-Brain Radiation Therapy in Patients With One to Four Brain Metastases (JCOG0504): A Phase III, Noninferiority, Randomized Controlled Trial.

Purpose Whereas whole-brain radiotherapy (WBRT) has been the standard treatment of brain metastases (BMs), stereotactic radiosurgery (SRS) is increasingly preferred to avoid cognitive dysfunction; however, it has not been clearly determined whether treatment with SRS is as effective as that with WBRT or WBRT plus SRS. We thus assessed the noninferiority of salvage SRS to WBRT in patients with BMs. Patients and Methods Patients age 20 to 79 years old with performance status scores of 0 to 2-and 3 if caused only by neurologic deficits-and with four or fewer surgically resected BMs with only one lesion > 3 cm in diameter were eligible. Patients were randomly assigned to WBRT or salvage SRS arms within 21 days of surgery. The primary end point was overall survival. A one-sided α of .05 was used. Results Between January 2006 and May 2014, 137 and 134 patients were enrolled in the WBRT and salvage SRS arms, respectively. Median overall survival was 15.6 months in both arms (hazard ratio, 1.05; 90% CI, 0.83 to 1.33; one-sided P for noninferiority = .027). Median intracranial progression-free survival of patients in the WBRT arm (10.4 months) was longer than that of patients in the salvage SRS arm (4.0 months). The proportions of patients whose Mini-Mental Status Examination and performance status scores that did not worsen at 12 months were similar in both arms; however, 16.4% of patients in the WBRT arm experienced grade 2 to 4 cognitive dysfunction after 91 days postenrollment, whereas only 7.7% of those in the SRS arm did ( P = .048). Conclusion Salvage SRS is noninferior to WBRT and can be established as a standard therapy for patients with four or fewer BMs.

Establishment of a Quick and Highly Accurate Breath Test for ALDH2 Genotyping.

OBJECTIVES: Acetaldehyde, the first metabolite of ethanol, is a definite carcinogen for the esophagus, head, and neck; and aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that catalyzes the metabolism of acetaldehyde. The ALDH2 genotype exists as ALDH2*1/*1 (active ALDH2), ALDH2*1/*2 (heterozygous inactive ALDH2), and ALDH2*2/*2 (homozygous inactive ALDH2). Many epidemiological studies have reported that ALDH2*2 carriers are at high risk for esophageal or head and neck squamous cell carcinomas by habitual drinking. Therefore, identification of ALDH2*2 carriers would be helpful for the prevention of those cancers, but there have been no methods suitable for mass screening to identify these individuals. METHODS: One hundred and eleven healthy volunteers (ALDH2*1/*1 carriers: 53; ALDH2*1/*2 carriers: 48; and ALDH2*2/*2 carriers: 10) were recruited. Breath samples were collected after drinking 100 ml of 0.5% ethanol using specially designed gas bags, and breath ethanol and acetaldehyde levels were measured by semiconductor gas chromatography. RESULTS: The median (range) breath acetaldehyde levels at 1 min after alcohol ingestion were 96.1 (18.1-399.0) parts per billion (p.p.b.) for the ALDH2*1/*1 genotype, 333.5 (78.4-1218.4) p.p.b. for the ALDH2*1/*2 genotype, and 537.1 (213.2-1353.8) p.p.b. for the ALDH2*2/*2 genotype. The breath acetaldehyde levels in ALDH2*2 carriers were significantly higher than for the ALDH2*1/*1 genotype. Notably, the ratio of breath acetaldehyde level-to-breath ethanol level could identify carriers of the ALDH2*2 allele very accurately (whole accuracy; 96.4%). CONCLUSIONS: Our novel breath test is a useful tool for identifying ALDH2*2 carriers, who are at high risk for esophageal and head and neck cancers.

Roles of the PDZ-binding motif of HPV 16 E6 protein in oncogenic transformation of human cervical keratinocytes.

The high-risk human papillomavirus E6 proteins have been shown to interact with and lead to degradation of PDZ-domain-containing proteins through its carboxy-terminal motif. This PDZ-binding motif plays important roles in transformation of cultured cells and carcinogenesis of E6-transgenic mice. However, its biological effects on the natural host cells have not been elucidated. We have examined its roles in an in vitro carcinogenesis model for cervical cancer, in which E6 and E7 together with activated HRAS (HRASG12V ) can induce tumorigenic transformation of normal human cervical keratinocytes. In this model, E6Δ151 mutant, which is defective in binding to PDZ domains, almost lost tumorigenic ability, whereas E6SAT mutant, which is defective in p53 degradation showed activity close to wild-type E6. Interestingly, we found decreased expression of PAR3 in E6-expressing cells independently of E6AP, which has not been previously recognized. Therefore, we knocked down several PDZ-domain containing proteins including PAR3 in human cervical keratinocytes expressing E7, HRASG12V and E6Δ151 to examine whether depletion of these proteins can restore the tumorigenic ability. Single knockdown of SCRIB, MAGI1 or PAR3 significantly but partially restored the tumorigenic ability. The combinatorial knockdown of SCRIB and MAGI1 cooperatively restored the tumorigenic ability, and additional depletion of PAR3 further enhanced the tumorigenic ability surpassing that induced by wild-type E6. These data highlight the importance of the carboxy-terminal motif of the E6 protein and downregulation of PAR3 in tumorigenic transformation of human cervical keratinocytes.

[Associations between Clinical Factors and Acute Renal Failure Due to Cisplatin Combination Chemotherapy for Lung Cancer].

In this study, we investigated the clinical factors associated with acute kidney injury (AKI) due to combination therapy with cisplatin (CDDP) for treating lung cancer. We classified cases according to the presence or absence of adequate hydration and magnesium(Mg)administered above the regulations of the registered regimen to evaluate the effect due to differences in hydration on AKI. We also investigated clinical factors before and after administration of CDDP in each case group, and examined their association with AKI. Seventy-four patients with lung cancer that were indicated for treatment with a CDDP combination regimen between December 2012 and April 2013 were studied. The patients whose conditions progressed to AKI of Bgrade 2 accounted for 0% (0/33) in the Mg administration group and 7.3%(3/41)in the Mg non-administration group. In particular, 2 cases of serious AKI (grade 4) were observed in the Mg non-administration without additional hydration group. When compared with other groups, a high antiemetic rate and favorable urine volume were observed in the Mg administration with additional hydration group. In the patients with AKI, many developed hyponatremia of Bgrade 3 within 1 week after administration of CDDP. Although Mg administration and ample hydration seem to be effective measures to deal with CDDP-caused AKI, comprehensive monitoring, including antiemesis therapy, after CDDP administration and correction of electrolytes is important.

Activation of NF-κB by human papillomavirus 16 E1 limits E1-dependent viral replication through degradation of E1.

UNLABELLED: NF-κB is a family of transcription factors that regulate gene expression involved in many processes, such as the inflammatory response and cancer progression. Little is known about associations of NF-κB with the human papillomavirus (HPV) life cycle. We have developed a tissue culture system to conditionally induce E1-dependent replication of the human papillomavirus 16 (HPV16) genome in human cervical keratinocytes and found that expression of HPV16 E1, a viral helicase, results in reduction of IκBα and subsequent activation of NF-κB in a manner dependent on helicase activity. Exogenous expression of a degradation-resistant mutant of IκBα, which inhibits the activation of NF-κB, enhanced E1-dependent replication of the viral genome. Wortmannin, a broad inhibitor of phosphoinositide 3-kinases (PI3Ks), and, to a lesser extent, VE-822, an ATR kinase inhibitor, but not KU55933, an ATM kinase inhibitor, suppressed the activation of NF-κB and augmented E1-dependent replication of the HPV16 genome. Interestingly, the enhancement of E1-dependent replication of the viral genome was associated with increased stability of E1 in the presence of wortmannin as well as the IκBα mutant. Collectively, we propose that expression of E1 induces NF-κB activation at least in part through the ATR-dependent DNA damage response and that NF-κB in turn limits E1-dependent replication of HPV16 through degradation of E1, so that E1 and NF-κB may constitute a negative feedback loop. IMPORTANCE: A major risk factor in human papillomavirus (HPV)-associated cancers is persistent infection with high-risk HPVs. To eradicate viruses from infected tissue, it is important to understand molecular mechanisms underlying the establishment and maintenance of persistent infection. In this study, we obtained evidence that human papillomavirus 16 (HPV16) E1, a viral DNA helicase essential for amplification of the viral genomes, induces NF-κB activation and that this limits E1-dependent genome replication of HPV16. These results suggest that NF-κB mediates a negative feedback loop to regulate HPV replication and that this feedback loop could be associated with control of the viral copy numbers. We could thus show for the first time that NF-κB activity is involved in the establishment and maintenance of persistent HPV infection.

Effect of preoperative administration of methylpredonisolone and ulinastatin on tumor cell metastasis after surgical stress.

Using a rat laparotomy stress model, we conducted a comparative analysis of postoperative organ metastasis after administration of ulinastatin (UTI) or methylprednisolone (MP), which have an inhibitory effect on cytokine production. The subjects were classified into 4 groups: 1) minimal laparotomy group (C group), 2) major laparotomy group (L group), 3) preoperative MP intravenous administration + major laparotomy group (MP group), and 4) preoperative UTI intravenous administration + major laparotomy group (UTI group). Either MP or UTI was administered intravenously before surgery, and RI-labeled cells were injected into the portal vein immediately after laparotomy to collect tissue specimens in order to measure radiation dosage. Then, the concentrations of serum IL-2 and IL-6, liver interleukin 1 beta (IL-1ß) and interleukin 10 (IL-10), and liver E-selectin were measured. In addition natural killer cell, (NK cell) activation and neoplastic nodules on the liver surface at 3 weeks after surgery were also measured. The adhesion rate of malignant cells to the liver was higher in the L group than in the C group, higher in the MP group than the L group, and lower overall in the UTI group. The concentration of IL-1ß and IL-6 were decreased in the MP and UTI groups compared to the L group. IL-2 was decreased significantly in the MP group compared with the C and L groups. E-selectin expression level decreased in the UTI group compared with the L group. NK cell activation decreased in the MP group compared with the C group and L group, but no differences were observed between the UTI and L groups. The number of tumor nodules on the surface of the liver increased in the MP group compared with the L group, and decreased in the UTI group compared with the L group. Postoperative alleviation of invasive reaction was suggested in both the MP and UTI groups. However, preoperative administration of MP increased metastasis while that of UTI inhibited metastasis. MP was considered to have decreased anti-tumor immunocompetence and promoted metastasis, while UTI was considered to have inhibited the expression of adhesive molecules and decreased metastasis.

Trans-kingdom horizontal DNA transfer from bacteria to yeast is highly plastic due to natural polymorphisms in auxiliary nonessential recipient genes.

With the rapid accumulation of genomic information from various eukaryotes in the last decade, genes proposed to have been derived from recent horizontal gene transfer (HGT) events have been reported even in non-phagotrophic unicellular and multicellular organisms, but the molecular pathways underlying HGT remain to be explained. The development of in vitro HGT detection systems, which permit the molecular and genetic analyses of donor and recipient organisms and quantify HGT, are helpful in order to gain insight into mechanisms that may contribute to contemporary HGT events or may have contributed to past HGT events. We applied a horizontal DNA transfer system model based on conjugal gene transfer called trans-kingdom conjugation (TKC) from the prokaryote Escherichia coli to the eukaryote Saccharomyces cerevisiae, and assessed whether and to what extent genetic variations in the eukaryotic recipient affect its receptivity to TKC. Strains from a collection of 4,823 knock-out mutants of S. cerevisiae MAT-α haploids were tested for their individual TKC receptivity. Two types of mutants, an ssd1 mutant and respiratory mutants, which are also found in experimental strains and in nature widely, were identified as highly receptive mutants. The TKC efficiency for spontaneously accrued petite (rho (-/0)) mutants of the functional allele (SSD1-V) strain showed increased receptivity. The TKC efficiency of the ssd1Δ mutant was 36% for bacterial conjugation, while that of the petite/ssd1Δ double mutants was even higher (220% in average) compared to bacterial conjugation. This increased TKC receptivity was also observed when other conjugal transfer systems were applied and the donor bacterium was changed to Agrobacterium tumefaciens. These results support the idea that the genomes of certain eukaryotes have been exposed to exogenous DNA more frequently and continuously than previously thought.

Potential roles of hyperbaric oxygenation in the treatments of brain tumors.

Over the past 50 years hyperbaric oxygen (HBO2) therapy has been used in a wide variety of medical conditions, and one of them is cancer. Many clinical studies have been conducted to evaluate potential therapeutic effects of HBO2 as a part of cancer treatment. This review briefly summaries the potential role of HBO2 therapy in the treatment of malignant tumors and radiation injury of the brain. HBO2 therapy is used for the enhancement of radiosensitivity in the treatment of some cancers, including malignant brain tumors. Radiotherapy within 15 minutes following HBO2 exposure, a relatively new treatment regimen, has been studied at several institutes and has demonstrated promising clinical results for malignant gliomas of the brain. HBO2 therapy also increases sensitivity to some antineoplastic agents; non-randomized clinical trials using carboplatin-based chemotherapy combined with HBO2 show a significant advantage in survival for recurrent malignant gliomas. The possibilities of combining HBO2 therapy with radiotherapy and/or chemotherapy to overcome newly diagnosed and recurrent malignant gliomas deserve extensive clinical trials. HBO2 therapy also shows promising potential for the treatment and/or prevention of radiation injury of the brain after stereotactic radiosurgery for brain lesions. The possibilities with HBO2 to enhance the therapeutic effect of irradiation per se, and to even increase the radiation dose if there are ways to combat the side effects, should boost new scientific interest into the whole field of oncology looking for new armamentaria to fight cancer.

[A case of aggressively growing bladder cancer in patient with long-term cystostomy due to spinal cord injury].

The patient was a 38-year-old man. A cystostomy catheter had been inserted when he was 23 years of age for neuropathic bladder due to cervical spinal cord injury at 20 years of age. Purulent discharge from around the cystotomy had continued for approximately 4 months. Examination revealed the formation of a subcutaneous tumor around the cystostomy, with elevated carcinoembryonic antigen (CEA) levels (459.4 ng/ml) in the blood. Urothelial carcinoma was detected using open biopsy. It was considered that primary urothelial carcinoma of the bladder had progressed along the cystostomy, and clinical stage 4 cT4N2M0 was diagnosed, with intrapelvic lymph node metastasis evident on imaging. Four courses of gemcitabine-cisplatin chemotherapy were administered; a partial response was obtained, after which cystectomy and ileal conduit formation were performed with the main aim of improving difficulty in urination. However, retroperitoneal lymph node and liver metastases were observed 1 month postoperation with rapid enlargement; the patient died approximately 2 months after the surgery. The CEA level was observed to be 18,998 ng/ml before he died. Here, we have reported this case with a discussion of the literature concerning the association between long-term indwelling catheter in patients with spinal cord injury and the development of bladder cancer.

Ramelteon combined with an α1-blocker decreases nocturia in men with benign prostatic hyperplasia.

BACKGROUND: Nocturia is defined as waking one or more times during the night due to the urge to void. Recently, the effectiveness of several sedatives and analgesics for nocturia has been reported. We herein investigated the effects of ramelteon, an antioxidant and sleep inducer, on nocturia unresponsive to α1-blocker monotherapy in males with lower urinary tract symptoms (LUTS) as a pilot study. METHODS: Subjects were 19 patients who had LUTS suggestive of benign prostate hyperplasia, received α1-blockers (tamsulosin, silodosin, or naftopidil), and continued to have two or more episodes of nocturia per night before starting ramelteon. Ramelteon at 8 mg once daily for one month was added to the α1-blocker. A self-administered questionnaire including the International Prostate Symptom Score (IPSS), quality of life (QoL) index, Overactive Bladder Symptom Score (OABSS), and Nocturia Quality-of-Life Questionnaire (N-QOL) were assessed before and one month after starting ramelteon. RESULTS: The mean score on IPSS question 7 (nocturia) decreased significantly from 2.88 before starting ramelteon to 2.41 one month after starting the medication (P = 0.03). The mean total OABSS decreased significantly from 6.31 to 5.38 (P = 0.03), and the mean for OABSS question 2 (nighttime frequency of nocturia) also significantly decreased from 2.63 to 2.13 (P = 0.01). The mean total N-QOL score did not change significantly. Two patients had dizziness; the remaining patients had no adverse drug-related events. CONCLUSIONS: Ramelteon in combination with an α1-blocker could be a treatment option for reducing nocturia in men with BPH.

Transkingdom genetic transfer from Escherichia coli to Saccharomyces cerevisiae as a simple gene introduction tool.

Transkingdom conjugation (TKC) permits transfer of DNA from bacteria to eukaryotic cells using a bacterial conjugal transfer system. However, it is not clear whether the process of DNA acceptance in a recipient eukaryote is homologous to the process of conjugation between bacteria. TKC transfer requires mobilizable shuttle vectors that are capable of conjugal transfer and replication in the donor and recipient strains. Here, we developed TKC vectors derived from plasmids belonging to the IncP and IncQ groups. We also investigated forms of transfer of these vectors from Escherichia coli into Saccharomyces cerevisiae to develop TKC as a simple gene introduction method. Both types of vectors were transferred precisely, conserving the origin of transfer (oriT) sequences, but IncP-based vectors appeared to be more efficient than an IncQ-based vector. Interestingly, unlike in agrobacterial T-DNA (transfer DNA) transfer, the efficiency of TKC transfer was similar between a wild-type yeast strain and DNA repair mutants defective in homologous recombination (rad51Δ and rad52Δ) or nonhomologous end joining (rad50Δ, yku70Δ, and lig4Δ). Lastly, a shuttle vector with two repeats of IncP-type oriT (oriT(P)) sequences flanking a marker gene was constructed. TKC transfer of this vector resulted in precise excision of both the oriT(P) loci as well as the marker gene, albeit at a low frequency of 17% of all transconjugants. This feature would be attractive in biotechnological applications of TKC. Taken together, these results strongly suggest that in contrast to agrobacterial T-DNA transfer, the circularization of vector single-stranded DNA occurs either before or after transfer but requires a factor(s) from the donor. TKC is a simple method of gene transfer with possible applications in yeast genetics and biotechnology.