Changes in prevalence of Helicobacter pylori in Japan from 2008 to 2018: a repeated cross-sectional study.

OBJECTIVES: To understand the recent prevalence and time trends of Helicobacter pylori infection rates in the Japanese population. DESIGN: Repeated cross-sectional study. PARTICIPANTS: A total of 22 120 workers (age: 35-65 years) from one Japanese company, who underwent serum H. pylori antibody tests in a health check-up between 2008 and 2018. MEASURES: H. pylori infection rates among participants aged 35 years from 2008 to 2018, and participants aged 35, 40, 45, and 50-65 years in 2018, based on the results of serum antibody tests, were analysed. In the 2018 analysis, in addition to the antibody test results, all participants who had undergone eradication treatment for H. pylori were considered as infected. Trends were examined using joinpoint analysis. RESULTS: H. pylori was detected in 1100 of 7586 male and 190 of 1739 female participants aged 35 years. Annual infection rates among those aged 35 years showed linear downward trends as follows: men, 17.5% in 2008 to 10.1% in 2018 (slope: -0.66); women, 12.3% in 2008 to 9.2% in 2018 (slope: -0.51) without joinpoints. In the 2018 analysis, 2432 of 9580 men and 431 of 1854 women were H. pylori positive. Infection rates tended to increase with older age (men: 11.0% (35 years) to 47.7% (65 years); women: 10.0% (35 years) to 40.0% (65 years)), and showed joinpoints in both sexes (men: 54 years; women: 45 years). Although both the first and second trends were upward, the second trend for both men and women was steeper than the first trend (p<0.05). CONCLUSIONS: Our study demonstrated that in the previous 11 years, infection rates of H. pylori in 35-year-old male and female Japanese workers have constantly decreased, and furthermore, analysis of various age groups showed joinpoints around 50 years, suggesting a consistent declining trend in H. pylori infection rates in Japan.

Factors that hinder medical career aspirations: A nationwide questionnaire survey of teachers in charge of career guidance in Japanese high schools.

Despite concerns raised on the inequality in healthcare provision in Japan, little is known about the factors that hinder candidates' application to medical schools. A nationwide cross-sectional survey was conducted to identify the impact of economic factors and living place on students' choice of and preparation for medical school. The survey was administered to high school teachers with career advisory roles, as they support and likely influence students' choice and decision on this matter. Responses totaling 1,094 were obtained from 1,746 high schools across Japan. The ratio of high schools with two or more students enrolled in medical schools every year is higher in private schools, those with high tuition, and those located in big cities. Approximately 66.8% of the respondents agreed that "It is difficult for students in economically disadvantaged families to enroll in medical schools;" 42.0% agreed that "Some students gave up on aspiring to enter medical schools because they could not afford it," and 61.2% agreed that "Students living in urban areas are more likely to enroll in medical schools." When asked about the percentage of students attending prep school among those aspiring for a medical career, significantly more respondents from private versus public high schools answered "80% or more." When asked about the percentage of parents who are doctors or dentists among students aspiring for a medical career, significantly more respondents from private versus public high schools answered "50% or more." The results suggest that students from lower-income families and those living in rural areas are more likely to be disadvantaged when choosing a medical career (because of financial difficulties) than those who live in urban areas and come from wealthier families. The results imply that economic and geographical divides in medical admission are reflected in high school teachers' perception of and support provided to students.

Medical School Staff's Standardized Patient Experience Alters their Understanding of Student Education.

Since knowledge of medical communication education and objective structured clinical examination (OSCE) is increasing, a greater number of simulated patients/standardized patients (SPs) will undoubtedly be needed throughout Japan. At Tokyo Medical University in Japan, non-medical professional school staff members have acted as SPs in post-clinical clerkship OSCEs. However, except for academic or medical staff, no other staff members were reported to have acted as SPs. Therefore, the significance of the large numbers of solely medical school staff acting as SPs needs to be investigated. The purpose of this study was to determine how acting as SPs affects medical school staff's understanding of student education and whether it is useful for university staff to know what kind of education is being provided at their own school. A mixed-method study was utilized to investigate what kind of attitudinal changes occurred among medical school staff after their SP experiences. Accordingly, the researchers conducted a questionnaire survey with staff members after they acted as SPs. The questionnaire was developed through semi-structured interviews. The majority of the participants' responses were positive. They claimed that they had gained knowledge on the testing of students and now understood the importance of doctors' communication skills. Furthermore, many stated that all staff members at medical schools should experience acting as SPs. Medical school staff understands students' education processes better after acting as SPs. Japan's SPs are aging and becoming fewer; however, these SP numbers could be supplemented by medical school staff members.

Less Invasive Management of Tissue Deficits for Deep Sternal Wound Infections.

BACKGROUND: The frequency of sternomyelitis after cardiovascular surgery has been reported to be 0.4% -5%. METHODS: The treatment method used for 47 patients (29 male and 18 female) who developed sternomyelitis after sternotomy with tissue defects in the chest was examined retrospectively. RESULTS: Of the original conditions, the most frequent was coronary artery disease undergoing bypass grafting (22 cases, 46.8%), followed by acute aortic dissection (10 cases, 21.3%). The number of times debridement was performed was: once, 35 cases; twice, 11 cases; 7 times, 1 case; and unknown, 2 cases. The most frequent time of occurrence of sternomyelitis was within 2 weeks after surgery (12 patients, 25.5%). A residual internal thoracic artery remained on both sides in 28 cases (59.6%), and only on the right side in 17 cases (36.2%); there was no remaining one in 2 cases (4.2%). The reconstruction method was a pectoralis major musculocutaneous flap in 31 cases (66.0%), internal mammary artery perforator flap in 7 cases (14.9%), rectus abdominis musculocutaneous flap in 4 cases (8.5%), omentum transplant in 3 cases (6.4%), superior epigastric artery perforator flap in 2 cases (4.3%), external abdominal oblique muscle flap in 1 case (2.1%), and latissimus dorsi musculocutaneous flap in 1 case (2.1%). The internal mammary artery perforator flap and the superior epigastric artery perforator flap have been effective treatment. CONCLUSIONS: In 47 patients, our method of treatment for tissue defects of the chest wall after sternal osteomyelitis was examined, and an algorithm using less invasive management was proposed.

Assessing the empathy of medical students during medical interview training in Japan by using mixed-methods surveys of simulated patients.

This article was migrated. The article was marked as recommended. Background: Medical interviews are performed during objective structured clinical examinations, to assess the communication skills of medical students. In particular, medical students are assessed regarding whether they demonstrate empathy during these staged interviews. However, no studies to date have analyzed the validity of the methods to evaluate empathy during objective structured clinical examinations. Aim: Here we sought to identify factors affecting whether simulated (standardized) patients (SPs) felt that the medical students had treated them empathetically during medical interview training. Methods: The training involved the participation of SPs during the bedside learning of fifth-year medical students in Japan. After the students completed medical interview training, we conducted a questionnaire-based survey. We developed the list of questionnaire items through semi-structured interviews asking SPs to describe when the student had been empathetic. Results: The item "I felt that the student was empathic throughout the interview" was significantly correlated with "I was given enough time to talk at the beginning of the interview," "The student made good eye contact," "The student's attitude was appropriate," "I was able to say enough of what I wanted to talk about," and "The student used phrases that expressed empathy." Multiple regression analysis revealed that "The student used phrases that expressed empathy" was the only independent predictor of "I felt that the student was empathic throughout the interview." Conclusions: The factor that correlated most strongly with the SP feeling that the student was empathic during a medical interview was "The student used phrases that expressed empathy." However, correlations also occurred with open-ended questions and the student's level of attention at the beginning of the interview and with the student's attitude. Together, these findings indicate that several types of both verbal and nonverbal communication determined whether SPs felt that medical students showed empathy during staged medical interviews.

In Situ Splitting of a Rib Bone Graft for Reconstruction of Orbital Floor and Medial Wall.

In situ splitting of rib bone graft was conducted in 22 patients for the repair of orbital fracture with no other complicating fractures. A bone graft was harvested from the sixth or seventh rib in the right side. The repair of the orbital floor and medial wall was successful in all the cases. Ten patients had bone grafting to the orbital floor, eight had it done onto medial wall, and 4 onto both floor and wall after reduction. The mean length of in situ rib bone graft was 40.9 mm (range, 20-70 mm), the mean width of these was 14.9 mm (range, 8-20 mm). The bone grafting was done by one leaf for 15 cases and two leafs for 7 cases in size of defects. The technique of in situ splitting of a rib bone graft for the repair of the orbital floor and medial wall is a simple and safe procedure, easily taking out the in situ splitting of a rib, and less pain in donor site. It has proved to be an optimal choice in craniofacial reconstruction, especially the defects of orbital floor and medial wall.

Evaluation of the rapid influenza detection tests GOLD SIGN FLU and Quick Navi-Flu for the detection of influenza A and B virus antigens in adults during the influenza season.

As the characteristics and accuracy of rapid influenza detection tests (RIDTs) vary, the development of a high-performance RIDT has been eagerly anticipated. In this study, the new RIDT GOLD SIGN FLU and the existing RIDT Quick Navi-Flu were evaluated in terms of detecting the antigens of influenza viruses A and B in Japanese adults with influenza-like symptoms. The study was performed from December 2013 to March 2014. Among the 123 patients from whom nasopharyngeal swab specimens were collected, 59 tested positive by viral isolation as the gold standard method (influenza A, n=38; influenza B, n=21). For GOLD SIGN FLU, the sensitivities were 73.7% and 81.0%, and the specificities were 97.6% and 98.0% for influenza A and B, respectively. For Quick Navi-Flu, the sensitivities were 86.8% and 85.7%, and the specificities were 98.8% and 100% for influenza A and B, respectively. The time to the appearance of the line on the test strip was less than 3min for influenza A and less than 2min for influenza B with both RIDTs in more than 90% of cases. GOLD SIGN FLU was useful for diagnosing influenza A, and the result was readily available for influenza B particularly among adult patients. Quick Navi-Flu showed better sensitivities and specificities than GOLD SIGN FLU.

Transconjunctival Approach for Zygomatic Fracture: A Single Surgeon's Experience of More Than 20 Years.

BACKGROUND: To let experts evaluate a single surgeon's experience with a combined transconjunctival and intraoral upper vestibular approach in the repair of zygomatic fractures encountered in 46 East Asian patients whom he treated over the past 20 years. METHODS: Patients were identified from a database, and a retrospective case note review was conducted. A total of 67 conjunctival and secondary incisions were made on 46 patients for repair of zygomatic fractures. All operative procedures were performed using a combination of transconjunctival and intraoral upper vestibular approaches to repair zygomatic fractures. RESULTS: The infraorbital rim and/or lateral buttress and/or lateral orbit was stabilized with titanium miniplates in 28 patients and absorbable miniplates in 11 patients. Seven patients required only reduction technique with no need of plates. Four cases needed additional canthotomy besides a conjunctival approach. No ectropion or entropion developed in any of the patients. Complications included eyelid laceration during surgery (n = 1), herniation of the conjunctiva (n = 1), temporary pyogenic granuloma of the conjunctiva after surgery (n = 1), and temporary entropion in a secondary incision (n = 1). CONCLUSIONS: A combined transconjunctival and intraoral upper vestibular approach in repairing zygomatic fractures is simple, easy, and effective, leaving no conspicuous facial scars. It is vitally important, however, that the surgeon masters the technique of transconjunctival approach well before he has good results in East Asian patients.

Aesthetic Total Reconstruction of Lower Eyelid Using Scapha Cartilage Graft on a Vascularized Propeller Flap.

BACKGROUND: The aim of this study was to review the results of a cohort of patients based on our experience with a new technique for total lower eyelid reconstruction after a large defect caused by malignant tumor and trauma. A scapha cartilage graft with small skin on a vascularized propeller flap was used for 16 cases requiring lower eyelid reconstruction. METHODS: Patients were identified from a database, and a retrospective case note review was conducted. The scapha cartilage graft was sutured to the margin of the defect of the palpebral conjunctiva and tarsus. The propeller flap, rotated by a perforator-based lateral orbital flap or a subcutaneous-based nasolabial flap, was vascularized on the scapha cartilage graft as anterior lining of the lower eyelid. The follow-up, including results of slit-lamp examination, lasted for varying periods, but often it was for 12 months. RESULTS: The scapha cartilage graft with small skin on a vascularized propeller flap was viable in all cases. Slit-lamp examination detected no irritation or injury of the conjunctiva and cornea, and visual acuity was maintained in all cases. A deformity in the donor helix by this technique was also improved by getting a smaller skin harvested from the scapha. CONCLUSION: Use of the scapha cartilage graft with small skin on a vascularized propeller flap allows for a good fit to the orbit, short operative time under local anesthesia, good graft viability, and a good esthetic result with minimal donor site morbidity.

How do case presentation teaching methods affect learning outcomes?--SNAPPS and the One-Minute preceptor.

BACKGROUND: Various techniques have been developed to enable preceptors to teach residents effectively in outpatient settings to promote active learning, including SNAPPS and the One-Minute Preceptor (OMP). This study aimed to ascertain the differences between SNAPPS and the OMP in case presentation content and learner evaluation when used to teach residents about case presentation. METHODS: From 2011 to 2013, participants were 71 junior clinical residents employed in two hospitals for clinical training. They were randomly allocated to two groups, one using SNAPPS and the other the OMP. From recorded discussions, the "differential diagnoses", "questions and uncertainties", "treatment plans", and "learning issues" were counted. Also, a self-evaluation form was distributed at the end of the study to evaluate the residents' satisfaction with the case presentation. RESULTS: Members of the SNAPPS group used significantly more meaning units related to questions and uncertainties compared with those of the OMP group (P < 0.001). Self-evaluation sheets revealed that members of the SNAPPS group had significantly higher positive responses than those of the OMP group in terms of the following evaluations: "It was easy to bring up questions and uncertainties" (P = 0.046), "It was easy to present the case efficiently" (P = 0.002), "It was easy to present the case in the sequence given" (P = 0.029), and "I was able to give an in-depth case presentation" (P = 0.005). CONCLUSIONS: SNAPPS may induce more meaning units related to questions and uncertainties and give more satisfaction to residents than the OMP.

Influenza Virus Induces Cholesterol-Enriched Endocytic Recycling Compartments for Budozone Formation via Cell Cycle-Independent Centrosome Maturation.

Influenza virus particles are assembled at the plasma membrane in concert with incorporation of the virus genome, but the details of its spatio-temporal regulation are not understood. Here we showed that influenza virus infection induces the assembly of pericentrosomal endocytic recycling compartment (ERC) through the activation of Rab11a GTPase and cell cycle-independent maturation of centrosome by YB-1, a multifunctional protein that is involved in mitotic division, RNA metabolism and tumorigenesis. YB-1 is recruited to the centrosome in infected cells and is required for anchoring microtubules to the centrosome. We also found that viral infection accumulates cholesterol in ERC and is dependent on YB-1. Depletion of YB-1 shows reduced cholesterol-enriched ERC and prevented budozone formation at the plasma membrane. These results suggest that cholesterol in recycling endosomes, which are emanated from ERC, may trigger the virus assembly concomitantly with the packaging of the virus genome. We propose that the virus genome is transported to the plasma membrane by cholesterol-enriched recycling endosomes through cell cycle-independent activation of the centrosome by YB-1.

[Comparison of Analgesic Efficacy between Posterior and Lateral Transversus Abdominis Plane Block Techniques for Laparoscopic Gynecological Surgery].

BACKGROUND: Posterior transversus abdominis plane (TAP) block has been considered as a useful technique for lower abdominal postoperative analgesia, but in ultrasound-guided block, its efficacy and usability are still unknown. We prospectively compared the analgesic efficacy among posterior and lateral TAP block and with control group in laparoscopic gynecological surgery. METHODS: 29 patients were randomly assigned to a study group. Ultrasound-guided TAP block was performed before the operation. In the posterior group (n =10), a needle was inserted from posterior to the middle axillary line, and its tip was centrally positioned at the origin of the transversus abdominis muscle. In the lateral group (n=10), a needle was inserted from the middle axillary line, and the tip was peripherally positioned at the surface of the transversus abdominis muscle. Visual analog scale (VAS), the use frequency of fentanyl rescue dose, and the period of time until initial rescue use after the operation were measured. RESULTS: In posterior group, pain scores both at rest and on movement were significantly lower than other groups at early phase (P<0.05). The number of uses of the fentanyl rescue dose was smaller in posterior group than in control group in the first 6 postoperative hours (1±1.2 vs 3±1.5, P<0.05). CONCLUSIONS: Ultrasound-guided posterior TAP block could become a more useful tool for postoperative analgesia. We presumed that its additional effect is caused from reduction of visceral pain related to sympathetic nerve block.

Prevalence of Helicobacter pylori infection with healthy subjects in Japan.

BACKGROUND AND AIM: Only few large-scale epidemiological studies have examined the prevalence of Helicobacter pylori (H. pylori) infection in Japan. The aim of the present study was to estimate the prevalence and incidence of H. pylori infection in Japan in terms of gender, age and region. METHODS: Serum anti-H. pylori antibody testing was included in workers' annual health checks conducted by T-company's health insurance association in 2008. The testing was continued for the next 5 years in 35-year-old subjects. RESULTS: The total number of subjects was 21 144 (18 398 males and 2746 females). Stratified for age, there were 5016 subjects (male:female=4219:797) in their 30s, 8748 (7770:978) in their 40s, 5589 (4807:782) in their 50s, and 1769 (1584:185) in their 60s. The H. pylori seropositive rate (male:female) was 27.5% (27.5:27.7) overall, 18.0% (18.3:16.1) in subjects in their 30s, 22.9% (22.7:24.7) in those in their 40s, 37.4% (37.2:38.2) in those in their 50s, and 46.1% (45.7:49.2) in those in their 60s. The prevalence of H. pylori seropositivity increased as age increased; however, no significant differences were seen between genders or among regions (χ2 test). The numbers of 35-year-old subjects from 2008 to 2012 were 1072, 1107, 941, 1065, and 940, respectively. The corresponding H. pylori seropositive rates were 17.4, 17.4, 14.3, 13.3, and 14.0%, respectively. CONCLUSION: The Japanese H. pylori infection rate had already declined to 27.5% in 2008, with subjects in the 35-70 age range. The prevalence of H. pylori infection is also decreasing gradually from 2008 to 2012.

The effect of different positions on lower limbs skin perfusion pressure.

We have encountered situations of patients with critical limb ischemia accompanied by pain at rest and necrosis, who hang their legs down from the bed during sleep. This lower limb position is known to be a natural position, which reduces pain in the lower extremity induced by ischemia. However, the effect of this position on blood flow of the lower extremity is poorly understood. We studied whether measurements of skin perfusion pressure (SPP) changes by leg position and the difference between healthy adults and patients with critical limb ischemia. The subjects of this study were 10 healthy adults and 11 patients with critical limb ischemia. Patients with critical limb ischemia, including both dorsum of foot and plantar of foot, having SPP of lower limbs of less than 40 mmHg (supine position) were the object of this study. SPP was measured on four positions (supine position, lower limbs elevation position, sitting position, and reclining bed elevation of 20(°) position). In sitting position, both the number of healthy adults and critical patients show significant increases in SPP compared with the other three positions. These results suggest that sitting position is effective to keep good blood stream of lower limbs not only in healthy adults but also in patients with critical limb ischemia. However, an appropriate leg position should not have lower limbs hang downwards for long periods time because edema is caused by the fall in venous return in lower limbs, and the wound healing is prolonged. Our clinical research could be more useful in the future, particularly in developing countries, for surgeons managing wounds in leg and foot and preserving ischemic limbs.

High-resolution computed tomography findings in a case of severe leptospira infection (Weil disease) complicated with Jarisch-Herxheimer reaction.

In this report, we describe a case of Weil disease. Chest x-ray and computed tomography (CT) findings showed temporary deterioration 1 day after the initiation of antibiotic treatment, and high-resolution CT findings with the patient's physical findings made us suspect pulmonary alveolar hemorrhage (PAH). We believed that the PAH had been induced by Weil disease and subsequently caused Jarisch-Herxheimer reaction. We confirmed the patient's contact history with mice, and symptoms improved immediately after starting appropriate treatments. Leptospirosis is a relatively rare cause of PAH. Therefore, the possibility of this disease should be included in the differential diagnosis, especially when high-resolution CT findings indicate PAH, and the imaging findings deteriorate rapidly after antibiotic therapy.

Ultrasound-mediated interferon ß gene transfection inhibits growth of malignant melanoma.

We investigated the effects of ultrasound-mediated transfection (sonotransfection) of interferon ß (IFN-ß) gene on melanoma (C32) both in vitro and in vivo. C32 cells were sonotransfected with IFN-ß in vitro. Subcutaneous C32 tumors in mice were sonicated weekly immediately after intra-tumor injection with IFN-ß genes mixed with microbubbles. Successful sonotransfection with IFN-ß gene in vitro was confirmed by ELISA, which resulted in C32 growth inhibition. In vivo, the growth ratio of tumors transfected with IFN-ß gene was significantly lower than the other experimental groups. These results may lead to a new method of treatment against melanoma and other hard-to-treat cancers.

Ultrasound activation of TiO2 in melanoma tumors.

Sonodynamic therapy (SDT) is a new modality using ultrasound (US) to activate certain chemical sensitizers for cancer therapy. In this study, the effect of US combined with a nanoparticle titanium dioxide (TiO(2)) on melanoma cell was investigated in vitro and in vivo. Melanoma cells (C32) were irradiated with US in the presence and/or absence of TiO(2). Cell viability was measured immediately after US irradiation (1MHz, 0.5 and 1.0W/cm(2) for 10s). The effect of the combination of TiO(2) and US exposure (1MHz, 1.0W/cm(2), 2 min duration) on subcutaneously implanted C32 solid tumors in mice were investigated by measuring tumor volume regression. The cell viability was significantly decreased only after US irradiation in the presence of TiO(2). In vivo results showed significant inhibition of tumor growth in groups treated with TiO(2) and US. To our knowledge, this is the first report to demonstrate the cell killing effect of TiO(2) nanoparticles under the irradiation US in vitro and in vivo.

Synergistic effect of ultrasound and antibiotics against Chlamydia trachomatis-infected human epithelial cells in vitro.

To investigate whether or not the combined ultrasound and antibiotic treatment is effective against chlamydial infection, a new ultrasound exposure system was designed to treat chlamydia-infected cells. First, the minimum inhibitory concentrations of antibiotics against Chlamydia trachomatis were determined. Infected cultures were treated with antibiotics then sonicated at intensity of 0.15 or 0.44 W/cm(2) with or without Bubble liposomes. After 48 or 72 h after infection, chlamydial inclusions were stained and examined by fluorescence microscopy. The internalization of dextran-fluorescein conjugates by ultrasound irradiation with Bubble liposomes was observed by fluorescence microscopy. The results showed that application of nanobubble-enhanced ultrasound caused no significant effect on cell viability and chlamydial infectivity. However, Doxycycline (1/2 MIC) or CZX (1.0 µg/ml) in combination with nanobubble-enhanced ultrasound dramatically reduced the number of inclusions compared with that administered with antibiotics only. Bubble dose-dependent synergy was also observed. After ultrasound irradiation at intensity of 0.44 W/cm(2) on the presence of Bubble liposomes, 10% of HeLa cells were observed to have internalized the dextran molecules. This study suggests the possibility of using nanobubble-enhanced ultrasound to deliver antibiotic molecules into cells to eradiate intracellular bacteria, such as chlamydiae, without causing much damage to the cells itself.

Hypotonia-induced cell swelling enhances ultrasound-induced mechanical damage to cancer cells.

INTRODUCTION: It has been shown that killing of suspended cells by low-intensity ultrasound (0.08-0.11 W/cm(2)) can be enhanced by a mild non-lethal hypotonic (146 mOsm) medium. PURPOSE: In this study we wished to determine whether hypotonia-induced cell swelling of suspension cells was directly related to enhancement of ultrasound-mediated cell killing, and to verify whether similar effects could be observed on circulating and attached cells. METHODS: U937 cells under mild hypotonia were exposed to ultrasound for different times with real-time monitoring of cell size using a particle-size-distribution analyzer. To study the effect on attached cells, HeLa cells were exposed to ultrasound while under hypotonia in an in vivo-simulated set-up. RESULTS: The result showed that the enhanced cell killing (up to more than twice) was directly proportional to hypotonia-induced cell swelling. Similar membrane damage based on PI staining could be observed on HeLa cells treated with hypotonia. An in vivo-simulated circulating system also showed similar findings for hypotonia-enhanced ultrasound cell killing. CONCLUSION: These findings showed that mild hypotonia can be used to augment the effect of ultrasound in the treatment of cancers, particularly leukemia. The results showing that such enhancement is related to cell swelling could guide us toward proper timing of sonication while under hypotonic treatment.

Growth inhibition of neurofibroma by ultrasound-mediated interferon γ transfection.

PURPOSE: We have previously shown that ultrasound-mediated transfection (sonotransfection) can be optimized using a concept based on the ultrasound-induced apoptosis produced in our in vitro experiments. At optimized conditions, we have shown, using five cancer cell lines, that sonotransfection is superior to other conventional nonviral methods. Interferon gamma (IFN-γ) transfection using lipofection has been found to markedly inhibit the proliferation of neurofibroma cell lines. In this study, we investigated whether sonotransfection of IFN-γ to neurofibroma cell lines can suppress cell proliferation. METHODS: The ultrasound device used was the SonoPore KTAC-4000, which is capable of various acoustic settings. Ultrasound transducers at an oscillation frequency of 1.011 MHz were used; the potential ideal conditions were an intensity of 0.17 W/cm(2) at a burst frequency of 0.5 Hz, 25% duty factor, and 30-s sonication duration. Cells were assayed at 3 and 5 days after sonication. RESULTS: The transfection efficiency was found to be 12%. The ultrasound-treated cells were successfully transfected with IFN-γ genes as detected by enzyme-linked immunosorbent assay, and the cell growth ratio in the IFN-γ sonotransfection group tended to be lower than that in the other experimental groups. CONCLUSION: These results suggested that IFN-γ sonotransfection could potentially become a nonsurgical method for treating skin lesions such as neurofibromas.