A non-coding RNA balancing act: miR-346-induced DNA damage is limited by the long non-coding RNA NORAD in prostate cancer.

BACKGROUND: miR-346 was identified as an activator of Androgen Receptor (AR) signalling that associates with DNA damage response (DDR)-linked transcripts in prostate cancer (PC). We sought to delineate the impact of miR-346 on DNA damage, and its potential as a therapeutic agent. METHODS: RNA-IP, RNA-seq, RNA-ISH, DNA fibre assays, in vivo xenograft studies and bioinformatics approaches were used alongside a novel method for amplification-free, single nucleotide-resolution genome-wide mapping of DNA breaks (INDUCE-seq). RESULTS: miR-346 induces rapid and extensive DNA damage in PC cells - the first report of microRNA-induced DNA damage. Mechanistically, this is achieved through transcriptional hyperactivation, R-loop formation and replication stress, leading to checkpoint activation and cell cycle arrest. miR-346 also interacts with genome-protective lncRNA NORAD to disrupt its interaction with PUM2, leading to PUM2 stabilisation and its increased turnover of DNA damage response (DDR) transcripts. Confirming clinical relevance, NORAD expression and activity strongly correlate with poor PC clinical outcomes and increased DDR in biopsy RNA-seq studies. In contrast, miR-346 is associated with improved PC survival. INDUCE-seq reveals that miR-346-induced DSBs occur preferentially at binding sites of the most highly-transcriptionally active transcription factors in PC cells, including c-Myc, FOXA1, HOXB13, NKX3.1, and importantly, AR, resulting in target transcript downregulation. Further, RNA-seq reveals widespread miR-346 and shNORAD dysregulation of DNA damage, replication and cell cycle processes. NORAD drives target-directed miR decay (TDMD) of miR-346 as a novel genome protection mechanism: NORAD silencing increases mature miR-346 levels by several thousand-fold, and WT but not TDMD-mutant NORAD rescues miR-346-induced DNA damage. Importantly, miR-346 sensitises PC cells to DNA-damaging drugs including PARP inhibitor and chemotherapy, and induces tumour regression as a monotherapy in vivo, indicating that targeting miR-346:NORAD balance is a valid therapeutic strategy. CONCLUSIONS: A balancing act between miR-346 and NORAD regulates DNA damage and repair in PC. miR-346 may be particularly effective as a therapeutic in the context of decreased NORAD observed in advanced PC, and in transcriptionally-hyperactive cancer cells.

IDENTIFICATION OF NOVEL BIOMARKERS FOR LUNG CANCER RISK IN HIGH LEVELS OF RADON BY PROTEOMICS: A PILOT STUDY.

Radon is the second most important risk factor for lung cancer after tobacco smoking. In Chiang Mai, Thailand, the values of indoor radon activity concentrations are considerably higher than global average values and it is a highest level among East Asian countries. The aim of our study is to identify novel biomarkers for lung cancer risk in high radon areas using a proteomic approach. In our transitional study, a total of 81 participants of non-smokers were examined, consist of 25 lung cancer patients (LC), 16 healthy controls from low levels of natural radiation areas (LLNRA) and 40 healthy controls from high levels of natural radiation areas (HLNRA). The results showed that a total of 799 differentially expressed proteins were identified. Among these, a total of 25 proteins were observed in both LC and HLNRA, but not in LINRA. Owing to the results obtained from this study, we also point out the research direction regarding the validation of some new candidate protein as a biomarker to screen population with high risk for lung cancer in the area with high levels of radon.

CHANGES OF ABSORBED DOSE RATE IN AIR BY CAR-BORNE SURVEY IN NAMIE TOWN, FUKUSHIMA PREFECTURE AFTER THE FUKUSHIMA DAIICHI NUCLEAR POWER PLANT ACCIDENT.

The latest car-borne survey was carried out by Hirosaki University in order to grasp the local distribution of the absorbed dose rate in air after the evacuation order was lifted on Namie Town in 2017. The car-borne survey of absorbed dose rate in air was carried out on most of the roads which were accessible by car in Namie Town using a 3-in × 3-in NaI(Tl) scintillation spectrometer. The range of the absorbed dose rate in air was calculated to be 0.041-11 µGy h-1. The distribution maps of the absorbed dose rate in air were drawn based on the data obtained during the surveys in 2011, 2015 and 2017. The comparison of these absorbed dose rates in air suggests that the elevated absorbed dose rate in air in Namie Town caused by the FDNPP accident may be decreasing faster than natural decline which includes weathering effect and physical decay due to the artificial decontamination.

ANNUAL EFFECTIVE DOSE ASSESSMENT DUE TO RADON AND THORON PROGENIES IN DWELLINGS OF KILIMAMBOGO, KENYA.

Human beings are continuously exposed to ionising radiation originating from natural or artificial sources. Uranium-238 and Thorium-232 found in building materials are important sources of radon and thoron in the indoor environment. The concentration levels of radon, thoron and thoron progeny were measured in mud-walled, metallic or iron sheet-walled and stone-walled modern houses in Kilimambogo region, Kenya for 3 months. Radon and thoron concentration levels were measured using passive radon-thoron discriminative monitors (RADUET), while thoron progeny concentrations as the equilibrium equivalent thoron concentration (EETC) were measured using thoron progeny monitors. The mean radon concentration levels in mud, metallic and stone-walled dwellings were 67 ± 11, 60 ± 10 and 75 ± 10 Bq m-3, respectively. The mean thoron concentration levels in the corresponding dwellings were 195 ± 36, 71 ± 24 and 161 ± 31 Bq m-3, respectively, while EETCs were 12 ± 2, 3 ± 1 and 7 ± 1 Bq m-3, respectively. The annual effective doses for radon were 1.3 ± 0.2, 1.1 ± 0.1 and 1.4 ± 0.2 mSv y-1 in mud, metallic and stone-walled houses while those from thoron estimated from EETC were 2.4 ± 0.4, 0.5 ± 0.1 and 1.5 ± 0.2 mSv y-1 in the corresponding houses, respectively.

Page Kidney Following a Nonepisode Protocol Renal Allograft Biopsy: A Case Report.

Page kidney refers to a clinical condition that is characterized by the acute onset of hypertension and renal dysfunction owing to external compression of the kidney by a hematoma, tumor, lymphocele, or urinoma. We report a case in which Page kidney occurred after a nonepisode protocol renal allograft biopsy. A 31-year-old man with end-stage renal disease received a living related kidney transplant from his father. One year later, a nonepisode protocol renal allograft biopsy was performed. A day later, the patient's serum creatinine level increased to 4.23 mg/dL, and a subcapsular renal hematoma was detected using ultrasonography and computed tomography. Page kidney was diagnosed, and immediate surgical removal of the hematoma was performed. Nine days after the operation, the patient's serum creatinine level had improved to 1.89 mg/dL. Page kidney is a serious but treatable complication of renal allograft biopsies, and clinicians should pay attention to such complications, even in the setting of nonepisode protocol renal allograft biopsies.

A potential role for the silent information regulator 2 homologue 1 (SIRT1) in periapical periodontitis.

AIM: To investigate the role played by silent information regulator 2 homologue 1 (SIRT1) during angiogenesis of periapical periodontitis. METHODOLOGY: Periapical granulomas were subjected to dual-colour immunofluorescence imaging and real-time polymerase chain reactions assaying the expression levels of SIRT1, vascular endothelial growth factor (VEGF) and VE-cadherin. The association between Ki-67 and SIRT1 expression was also examined. Human umbilical vein endothelial cells (HUVECs) were treated with a combination of lipopolysaccharide and resveratrol (a SIRT1 activator) or sirtinol (a SIRT1 inhibitor); and the levels of mRNAs encoding SIRT1, VEGF and VE-cadherin were determined. HUVEC tube formation was assayed in the presence of resveratrol or sirtinol. The Mann-Whitney U-test or the Tukey-Kramer test was used for statistical analysis. RESULTS: Ki-67-expressing cells, including endothelial cells, lay adjacent to SIRT1-expressing cells in periapical granulomas. In addition, SIRT1-expressing cells were detected adjacent to VEGF-expressing cells and VEGF- or VE-cadherin-expressing endothelial cells. SIRT1, VEGF and VE-cadherin mRNA expression levels in periapical granulomas were significantly higher (P = 0.0054, 0.0090 and 0.0090, respectively) than those in healthy gingival tissues. HUVECs treated with resveratrol exhibited significantly higher expression of mRNAs encoding SIRT1, VEGF and VE-cadherin (P = 0.0019, 0.00005 and 0.0045, respectively) compared with controls, but sirtinol inhibited such expression. Resveratrol caused HUVECs to form tube-like structures, whilst sirtinol inhibited this process. CONCLUSIONS: These findings suggest that SIRT1 may stimulate angiogenesis in periapical granulomas by triggering the proliferation of endothelial cells and inducing VEGF and VE-cadherin expression.

Change in oral health status associated with menopause in Japanese dental hygienists.

OBJECTIVES: Oral symptoms such as xerostomia and burning mouth syndrome have been recognized to increase associated with menopause. The purpose of this study was to clarify the changes in oral health as well as systemic health due to menopause and their relations with hormonal change and mental status. METHODS: Ninety-seven female dental hygienists aged 40-59 years were assigned to premenopausal, menopausal and post-menopausal groups based on self-reported menstrual condition. Subjective health statuses were evaluated by questionnaire, and objective holistic and oral statuses were evaluated by measuring serum 17ß-estradiol (E2), salivary flow rate, α-amylase and secretory IgA (SIgA) and taste sensitivity. RESULTS: A significant difference among the three groups was observed in the self-rating questionnaire of depression (SRQ-D) score and serum E2 level as well as unstimulated salivary flow rate, whereas no significant difference was observed in Simplified menopausal index, Short-Form 36-Item Health Survey, General Oral Health Assessment Index, salivary α-amylase activity, salivary SIgA concentration and taste threshold. Serum E2 levels positively correlated with unstimulated salivary flow rates and negatively correlated with SRQ-D scores and α-amylase activities. CONCLUSIONS: The results demonstrated a negative correlation between E2 levels and SRQ-D scores as well as salivary α-amylase activities, suggesting an influence of E2 on mental condition. Furthermore, E2 decrease may result in reduction of salivary flow which in turn causes various problems of oral health. Since the participants were graduates from several dental hygienist schools and working at various places, these results can be generalized to Japanese dental hygienists to some extent.

Orthotopic Kidney Transplantation in an Elderly Patient With Various Severe Comorbid Conditions: A Case Report.

In recent years, the frequency of high-risk kidney transplantations has increased. We report a case in which a 72-year-old man with various severe comorbidities (prostate cancer, diabetes mellitus, complete atrioventricular block, coronary artery stenosis, severe stenosis of the popliteal arteries, and severe calcification of the iliac arteries) who received an orthotopic kidney transplantation. To prevent the occurrence of acute limb ischemia due to the steal phenomenon (caused by the kidney graft), we decided that a heterotopic kidney transplantation involving the iliac arteries was not an appropriate option. Therefore, as an alternative, left native nephrectomy was performed followed by an orthotopic kidney transplantation to the native renal artery and renal vein through a left subcostal incision. Postoperative ureteral stenosis occurred, and so stent exchange was required every 6 months. Despite the ureteral complication, the patient's serum creatinine level was 1.5 mg/dL at 2 years after the procedure.

In-situ straining and time-resolved electron tomography data acquisition in a transmission electron microscope.

This paper reports the preliminary results of a new in-situ three-dimensional (3D) imaging system for observing plastic deformation behavior in a transmission electron microscope (TEM) as a directly relevant development of the recently reported straining-and-tomography holder [Sato K et al. (2015) Development of a novel straining holder for transmission electron microscopy compatible with single tilt-axis electron tomography. Microsc. 64: 369-375]. We designed an integrated system using the holder and newly developed straining and image-acquisition software and then developed an experimental procedure for in-situ straining and time-resolved electron tomography (ET) data acquisition. The software for image acquisition and 3D visualization was developed based on the commercially available ET software TEMographyTM. We achieved time-resolved 3D visualization of nanometer-scale plastic deformation behavior in a Pb-Sn alloy sample, thus demonstrating the capability of this system for potential applications in materials science.

Randomized clinical trial comparing two vessel-sealing devices with crush clamping during liver transection.

BACKGROUND: Previous RCTs have failed to demonstrate the usefulness of combining energy devices with the conventional clamp crushing method to reduce blood loss during liver transection. Here, the combination of an ultrasonically activated device (UAD) and a bipolar vessel-sealing device (BVSD) with crush clamping was investigated. METHODS: Patients scheduled to undergo hepatectomy at the University of Tokyo Hospital or Nihon University Itabashi Hospital were eligible for this parallel-group, single-blinded randomized study. Patients were assigned to a control group (no energy device used), an UAD group or a BVSD group. The primary endpoint was the volume of blood loss during liver transection. Outcomes of the control group and the combined energy device groups (UAD plus BVSD) were first compared. Pairwise comparisons among the three groups were made for outcomes for which the combined energy device group was superior to the control group. RESULTS: A total of 380 patients were enrolled between July 2012 and May 2014; 116 patients in the control group, 122 in the UAD group and 123 in the BVSD group were included in the final analysis. Median blood loss during liver transection was lower in the combined energy device group (245 patients) than in the control group (116 patients): median 190 (range 0-3575) versus 230 (range 3-1570) ml (P = 0·048). Pairwise comparison revealed that blood loss was lower in the BVSD group than in the control group (P = 0·043). CONCLUSION: The use of energy devices combined with crush clamping reduced blood loss during liver transection. Registration number: C000008372 (www.umin.ac.jp/ctr/index.htm).

Effectiveness of Bortezomib in a Patient With Acute Rejection Associated With an Elevation of Donor-Specific HLA Antibodies After Small-Bowel Transplantation: Case Report.

BACKGROUND: A significant association between donor-specific antibody (DSA) and graft rejection has recently been documented. However, confirmed strategy has not been established for DSA-associated rejection after intestinal transplantation (ITx). CASE REPORT: A 20-year-old male patient with chronic intestinal obstruction caused by hypoganglionosis of the entire intestine underwent cadaveric donor ITx with grafting performed on 232 cm of the small intestine, cecum, and a part of the ascending colon. On post-operative day (POD) 14, a histological evaluation showed an acute rejection of indeterminate grade. The patient had severe acute rejection on POD 16, which prompted us to administer bolus steroids and polyclonal anti-thymocyte antibody, along with baseline maintenance immunosuppression. The histopathological findings of the graft indicated typical acute cellular rejection, although C4d was positive. We then detected donor-specific HLA antibody. The patient initially responded well to the therapy and showed decreased histological rejection signs. However, the refractory low-grade rejection persisted in the graft. During this period, the patient showed increased levels of DSA, and we speculated that the persistent rejection was associated with DSA; thus, bortezomib was administered at this stage as a salvage therapy. This rejection was thereafter successfully controlled without severe adverse effect. Twenty-three months after ITx, the patient is currently alive with complete enteral autonomy. CONCLUSIONS: A case of acute graft rejection followed by a marked elevation of DSA is presented. In this particular case, a modified treatment protocol using bortezomib in addition to the typical immunosuppressive agents was effective.

The role of PSMB9 upregulated by interferon signature in the pathophysiology of cutaneous lesions of dermatomyositis and systemic lupus erythematosus.

BACKGROUND: Dermatomyositis (DM) and systemic lupus erythematosus (SLE) have common skin features, including dermal mucin deposition and interferon signature, although their roles are unknown. OBJECTIVES: To identify common or specific molecular changes in DM and SLE skin. METHODS: Proteomic analysis was performed using DM and healthy skin. Glycosaminoglycans were analysed by high-performance liquid chromatography. RESULTS: The expression of 60 proteins was upregulated or downregulated in DM skin compared with healthy skin in the proteomic analysis. Among those proteins, PSMB9, an immunoproteasome subunit, was upregulated in the epidermis of DM and SLE, but not in other skin diseases. Furthermore, versican V1, a core protein for glycosaminoglycans, was upregulated, while type I collagen was downregulated in the dermis of DM and SLE skin. Interferon stimulated PSMB9 expression in cultured keratinocytes and reduced collagen expression in dermal fibroblasts, but did not affect versican expression. The PSMB9 knock-down in keratinocytes led to significant suppression of transforming growth factor (TGF)-ß2 and TGF-ß3, inducers of versican synthesis. TGF-ß3 expression was upregulated in both DM and SLE, while TGF-ß2 expression was increased only in the DM epidermis. ΔDiHS-diS1, a component of heparan sulfate, was significantly increased only in DM. TGF-ß2 expression significantly increased the ΔDiHS-diS1 expression in dermal fibroblasts in vitro. CONCLUSIONS: The interferon signature in DM and SLE skin reduces collagen in dermal fibroblasts, whereas overexpression of PSMB9 induced by interferon stimulates versican inducers in epidermal keratinocytes. In addition, the TGF-ß2-ΔDiHS-diS1 pathway may be responsible for the specific molecular change in DM skin.

Comparative dosimetry for radon and thoron in high background radiation areas in China.

The present study focuses on internal exposure caused by the inhalation of radon and thoron progenies because the internal exposures have not yet been clarified. For their dose assessment, radon, thoron and thoron progeny concentrations were measured by passive monitors over a long period (for 6 months). Consequently, radon, thoron and equilibrium equivalent thoron concentrations were given as 124 ± 78, 1247 ± 1189 and 7.8 ± 9.1 Bq m(-3), respectively. Annual effective doses are estimated to be 3.1 ± 2.0 mSv for radon and 2.2 ± 2.5 mSv for thoron. Total dose are estimated to be 5.3 ± 3.5 mSv a(-1). The present study has revealed that the radon dose was comparable with the thoron dose, and the total dose was ∼2 times higher than the worldwide average.

Urinary tract reconstruction using uretero-ureteral end-to-side anastomosis in kidney transplant recipients.

BACKGROUND: In kidney transplant recipients, the most widely used method for the reconstruction of the urinary pathway is ureteroneocystostomy, which may be difficult in cases with disused atrophic bladder. In this study, we evaluated kidney transplant recipients who underwent uretero-ureteral end-to-side anastomosis (UUA) in urinary reconstruction due to disused atrophic bladder. METHODS: To clarify the effectiveness of this method, we retrospectively reviewed the clinical records of kidney transplant recipients in our hospital. RESULTS: A total of 9 recipients with urinary reconstruction using UUA were evaluated. All of these patients had a history of long-term hemodialysis before transplantation, accompanied by complete anuria and small capacity of the bladder. In 4 patients, cranial native ureter was ligated, whereas it was not ligated in the remaining 5 patients. In 2 of 4 patients with cranial ligation, hydronephrosis developed in the native kidney with no further treatment being required. No patients experienced urinary tract complications including hydronephrosis in the graft, urine extravasation, or urinary tract infection in the follow-up period (757.6 ± 491.3 days). Allograft function was maintained well in all patients (serum creatinine level, 1.08 ± 0.23 mg/dL). CONCLUSIONS: Although UUA is not a routine method of urinary reconstruction in kidney transplantation, it can be safely performed and should be a surgical option, especially for recipients with disused atrophic bladder. The ligation of cranial native ureter may lead to hydronephrosis of the native kidney, and it is tentatively concluded that UUA without native ureteral ligation is clinically feasible.

An improved phase shift reconstruction algorithm of fringe scanning technique for X-ray microscopy.

The X-ray phase imaging method has been applied to observe soft biological tissues, and it is possible to image the soft tissues by using the benefit of the so-called "Talbot effect" by an X-ray grating. One type of the X-ray phase imaging method was reported by combining an X-ray imaging microscope equipped by a Fresnel zone plate with a phase grating. Using the fringe scanning technique, a high-precision phase shift image could be obtained by displacing the grating step by step and measuring dozens of sample images. The number of the images was selected to reduce the error caused by the non-sinusoidal component of the Talbot self-image at the imaging plane. A larger number suppressed the error more but increased radiation exposure and required higher mechanical stability of equipment. In this paper, we analyze the approximation error of fringe scanning technique for the X-ray microscopy which uses just one grating and proposes an improved algorithm. We compute the approximation error by iteration and substitute that into the process of reconstruction of phase shift. This procedure will suppress the error even with few sample images. The results of simulation experiments show that the precision of phase shift image reconstructed by the proposed algorithm with 4 sample images is almost the same as that reconstructed by the conventional algorithm with 40 sample images. We also have succeeded in the experiment with real data.

Revision of the Massarineae (Pleosporales, Dothideomycetes).

We here taxonomically revise the suborder Massarineae (Pleosporales, Dothideomycetes, Ascomycota). Sequences of SSU and LSU nrDNA and the translation elongation factor 1-alpha gene (tef1) are newly obtained from 106 Massarineae taxa that are phylogenetically analysed along with published sequences of 131 taxa in this suborder retrieved from GenBank. We recognise 12 families and five unknown lineages in the Massarineae. Among the nine families previously known, the monophyletic status of the Dictyosporiaceae, Didymosphaeriaceae, Latoruaceae, Macrodiplodiopsidaceae, Massarinaceae, Morosphaeriaceae, and Trematosphaeriaceae was strongly supported with bootstrap support values above 96 %, while the clades of the Bambusicolaceae and the Lentitheciaceae are moderately supported. Two new families, Parabambusicolaceae and Sulcatisporaceae, are proposed. The Parabambusicolaceae is erected to accommodate Aquastroma and Parabambusicola genera nova, as well as two unnamed Monodictys species. The Parabambusicolaceae is characterised by depressed globose to hemispherical ascomata with or without surrounding stromatic tissue, and multi-septate, clavate to fusiform, hyaline ascospores. The Sulcatisporaceae is established for Magnicamarosporium and Sulcatispora genera nova and Neobambusicola. The Sulcatisporaceae is characterised by subglobose ascomata with a short ostiolar neck, trabeculate pseudoparaphyses, clavate asci, broadly fusiform ascospores, and ellipsoid to subglobose conidia with or without striate ornamentation. The genus Periconia and its relatives are segregated from the Massarinaceae and placed in a resurrected family, the Periconiaceae. We have summarised the morphological and ecological features, and clarified the accepted members of each family. Ten new genera, 22 new species, and seven new combinations are described and illustrated. The complete ITS sequences of nrDNA are also provided for all new taxa for use as barcode markers.

Production cross sections of niobium and tantalum isotopes in proton-induced reactions on (nat)Zr and (nat)Hf up to 14 MeV.

Production cross sections of Nb and Ta isotopes in the proton-induced reactions on (nat)Zr and (nat)Hf, respectively, were measured up to 14 MeV using a stacked-foil technique. The observed nuclides in the (nat)Zr(p,x) reactions were (90g,91m,92m,95m,95g,96)Nb, (95)Zr, and (87g,88)Y. In the (nat)Hf(p,x) reactions, (175,176,177,178,179)Ta and (175)Hf were observed. The obtained cross sections for each nuclide were compared with the previously reported data and with the theoretical cross sections calculated by the TALYS-1.4 code. Thick-target yields of the observed nuclides were deduced from the measured production cross sections.

Assessment of spontaneous platelet aggregation using laser light scattering in healthy subjects: an attempt to standardize.

INTRODUCTION: When measuring platelet aggregation using laser light scattering, small aggregates forming without the addition of agonists may be observed. This event is called 'spontaneous platelet aggregation (SPA)'. The platelet hyperactivity observed in arterial thrombotic diseases can be detected with relative ease by measuring SPA. Standardization is urgently needed because of differences between measurement conditions among various laboratories. METHODS: We conducted a systematic study of factors that affect SPA measurement, compared SPA results to flow cytometry detection of surface antigens expressed on activated platelet membranes (P-selectin, activated glycoprotein IIb/IIIa), and determined conditions that yield stable measurements. RESULTS AND CONCLUSIONS: We evaluated results from 125 healthy volunteers and established conditions for a stable measurement of SPA. As the occurrence of SPA tended to increase with age, we determined conditions valid for subjects aged 20-60 years. Blood should be collected using a syringe, and the sample should be prepared after allowing the whole blood to rest for 30 min after collection. To isolate platelet-rich plasma, a 2-mL tube should be used and centrifuged at 150 g. The sample should be stored at room temperature, the platelet count of the sample should be (250 ± 10) × 10(9) /L, and the measurement should be completed within 90 min of blood collection.

Discrimination of lymph node metastases using desorption electrospray ionisation-mass spectrometry imaging.

Desorption electrospray ionisation mass spectrometry imaging (DESI-MSI) has been used for the identification of cancer within lymph nodes with accurate spatial distribution in comparison to gold standard matched immuno-histopathological images. The metabolic profile of the cancerous lymph nodes was similar to that of the primary tumour site.

Note: Near-field imaging of thermal radiation at low temperatures by passive millimeter-wave microscopy.

Imaging of thermal radiation with a spatial resolution below the diffraction limit is demonstrated with a passive millimeter-wave microscope. This technique utilizes a sensitive radiometric receiver in combination with a scanning near-field microscope. Experiments were performed at 50 GHz (λ = 6 mm) with sample temperatures ranging from room temperature down to 160 K, and the performance was shown to be superior to that achieved with passive imaging systems in the infrared region. The images are affected by non-uniformities in the transmission of thermal radiation from the sample to the receiver via the near-field probe and the reflection of thermal radiation back to the receiver from the probe. The effects of these non-uniformities were successfully removed using a sample image acquired by active measurements using a vector network analyzer.