Use of Oral Sildenafil in Treatment of Pediatric Head and Neck Lymphatic Malformations

Background: Lymphatic malformation (LMs) is a low flow vascular malformation, with a morbidity rate of 1/2000 in neonates. Most of the LMs were found in the head and neck. Compared with the macrocrystic ones, the microcrystic LMs show stronger invasiveness and wider involved range, which leads to higher treatment difficulty and recurrence rate as well as a serious impact on patients´ health and quality of life. Aim: To evaluate the efficacy and safety of oral sildenafil in treatment of pediatric head and neck LMs. Methods: In total, 21 children diagnosed with LMs were given oral sildenafil and stopped at week 24. Therapeutic outcome was evaluated by comparing lesions' volume change with baseline. In addition, symptoms improvement and adverse effects were also recorded during the follow-up period. Results: Eight patients (38.0%) showed excellent improvement (>75%-100%), 1 patient (4.8%) had good (>50%-75%), 2 patients (9.6%) had fair (>25%-50%), 3 patients (14.3%) had minimal (0%-25%), and 7 patients (33.3%) had no improvement. The snoring or stridor completely disappeared in 2 subjects, although there was no apparent decrease in LMs size. Moreover, all 3 patients with macrocystic lesions displayed a positive response to sildenafil treatment, followed by mixed type (9/12, 75%). Only 2 out of 6 patients with microcystic lesions had minimal clearance. Only 4 patients showed transient mild diarrhea, there was no other adverse effect in this series. Conclusion: Our study showed that low-dose oral sildenafil citrate tablets are safe and effective to decrease the lesions volume in some LMs children, especially with macrocystic lesion or mixed type.

[Clinical analysis of thyroid cancer in 62 children]

Objective: To analyze the clinical characteristics and prognosis of thyroid cancer in children. Methods: Clinical data of 164 children (60 boys, 104 girls) with space-occupying lesions of the thyroid who were hospitalized in Beijing Children's Hospital Affiliated to Capital Medical University from July 2006 to December 2017 were collected. Sixty-two children with thyroid cancer were reviewed respectively and followed up by telephone. Results: From July 2006 to December 2017, children with thyroid cancer accounted for 37.8% (62/164) of children with space-occupying lesions of the thyroid. The number of children with space-occupying lesions of the thyroid every 2 years was 13, 21, 19, 33, 38, 41, and the number of children with thyroid cancer every 2 years was 2, 5, 3, 8, 21, 23. One out of 62 thyroid cancer was follicular thyroid cancer, the others were papillary thyroid cancer, neck mass was the chief complaint in 60 of 62 patients. Two cases were brought to hospital with respiratory tract oppression as the chief complaint. Forty-eight cases got long-term follow-up by telephone, over 50 percent of cases received follow-up for more than 2 years, the median follow-up time was 2.63 years (0.25-8.67 years), most of these patients had favorable prognoses. Hypothyroidism (98%) and hypocalcemia (33%) were main long-term complication. Hypothyroidism recovered well after thyroxine replacement therapy, and in only 5 children hypocalcemia was spontaneously relieved, the average remission time was 1.9 months, the longest time for recovering from hypocalcemia was 6 months; the other cases responded well when they were treated as secondary hypoparathyroidism, with no hypocalcemia symptoms. Nine children had distant metastasis after operation, the average recurrence time was 12.8 months, and the latest relapsing time was 2 years. The overall prognosis was good, the longest follow-up period was 8 years and no death was found. Conclusions: Pediatric space-occupying lesions of the thyroid and thyroid cancer are rising during the last 12 years. Hypothyroidism and hypocalcemia are main long-term complications after surgery, the children cases recovered well, the remission of hypocalcemia was achieved not later than 6 months. The overall prognosis of childhood thyroid cancer was good, without death within the follow-up period.

[The prevalence of snoring and its association with academic performance among school-aged children in Beijing]

Objective: To investigate the snoring status of school-aged children in Beijing and explore the association of snoring and academic performance. Methods: A total of 7 925 children aged from 6 to 14 were selected from 15 primary and middle schools at 7 districts (Xicheng, Chaoyang, Changping, Shunyi, Fangshan, Huairou and Mentougou) in Beijing in 2015, using multi-stage stratified cluster random sampling method. The recruited children were asked to complete the Pediatric Sleep Questionnaire (PSQ) and a questionnaire related to sleep behavior. The multiplelogistic regression was used to analyze the association of snoring and academic performance. Results: A total of 794 (12.44%) children showed a decline in academic performance among 6 383 eligible respondentsfor data analysis. 580 (9.08%) children with snoring was identified, of which 333 and 247 were in frequency of 1-2 times per week and frequency of ≥3 times per week, respectively; 357, 170 and 53 were in snoring grade Ⅰ, grade Ⅱ and grade Ⅲ, respectively. Compared with the children without snoring, the OR (95%CI) for children with 1-2 times per week and ≥3 times per week was 1.363 (1.000-1.857) and 1.605 (1.135-2.269), respectively; and the OR (95%CI) for children with grade Ⅰ, grade Ⅱ and grade Ⅲ of snoring was 1.226 (0.893-1.683), 1.595 (1.062-2.397) and 2.31 (1.17-4.565), respectively. Conclusion: There is a statistical relationship between snoring and the decline of academic performance. The decline of academic performance positively associated with increased frequency and grade of snoring.

Appropriate dose of Lactobacillus buchneri supplement improves intestinal microbiota and prevents diarrhoea in weaning Rex rabbits

This study examined the effects on intestinal microbiota and diarrhoea of Lactobacillus buchneri supplementation to the diet of weaning Rex rabbits. To this end, rabbits were treated with L. buchneri at two different doses (LC: 104 cfu/g diet and HC: 105 cfu/g diet) for 4 weeks. PCR-DGGE was used to determine the diversity of the intestinal microbiota, while real-time PCR permitted the detection of individual bacterial species. ELISA and real-time PCR allowed the identification of numerous cytokines in the intestinal tissues. Zonula occludens-1, polymeric immunoglobulin receptor and immunoglobulin A genes were examined to evaluate intestinal barriers. Results showed that the biodiversity of the intestinal microbiota of weaning Rex rabbits improved in the whole tract of the treated groups. The abundance of most detected bacterial species was highly increased in the duodenum, jejunum and ileum after L. buchneri administration. The species abundance in the HC group was more increased than in the LC group when compared to the control. Although the abundance of Enterobacteriaceae exhibited a different pattern, Escherichia coli was inhibited in all treatment groups. Toll-like receptor (TLR)2 and TLR4 genes were down-regulated in all intestinal tissues as the microbiota changed. In the LC group, the secretion of the inflammatory cytokine tumour necrosis factor-α was reduced, the gene expression of the anti-inflammatory cytokine interleukin (IL)-4 was up-regulated and the expression of intestinal-barrier-related genes was enhanced. Conversely, IL-4 expression was increased and the expression of other tested genes did not change in the HC group. The beneficial effects of LC were greater than those of HC or the control in terms of improving the daily weight gain and survival rate of weaning Rex rabbits and reducing their diarrhoea rate. Therefore, 104 cfu/g L. buchneri treatment improved the microbiota of weaning Rex rabbits and prevented diarrhoea in these animals.

Efficacy and safety of sublingual immunotherapy with Dermatophagoides farinae drops in pre-school and school-age children with allergic rhinitis

BACKGROUND

The safety and efficacy of sublingual immunotherapy (SLIT) have been confirmed by many studies. However, in China, the research on efficacy and safety in young and older children with allergic rhinitis (AR) is still rare.

OBJECTIVE

The aim of this retrospective study is to evaluate the efficacy and safety of SLIT with Dermatophagoides farinae drops in pre-school and school-age children with AR.

METHODS

A total of 282 subjects aged 2-13 years with AR received a two-year course of sublingual immunotherapy along with pharmacotherapy. According to the age, patients were defined as the pre-school group (2-6 years old, n=116) and school-age group (7-13 years old, n=166). Total nasal rhinitis symptom scores (TNSS), visual analogue score (VAS) and total medication scores (TMS) were evaluated at four time points: baseline, after SLIT for half a year, one year and two years. The adverse events (AEs) were evaluated at each visit.

RESULTS

After two-year SLIT, the four rhinitis symptom scores, TNSS, VAS and TMS scores were significantly lower than baseline (all P<0.05). The comparison of efficacy between one and two-year duration showed no significant difference in global clinical outcomes (all P>0.05). In addition, there were no significant differences between the pre-school and school-age group in TNSS (all P>0.05), VAS (all P>0.05) and TMS scores (P>0.05) after SLIT for half a year, one year and two years. No severe systemic AEs were reported.

CONCLUSION

SLIT with D. farinae drops is clinically effective and safe in pre-school and school-age patients with house dust mites (HDMs)-induced AR.

[Laryngotracheal stenosis in children]

Laryngotracheal stenosis includes congenital laryngotracheal stenosis and secondary laryngotracheal stenosis. Congenital laryngotracheal anomalies are rare, accounting for 0.3%-1.0% of all laryngotracheal stenosis(LTS). Despite the management of pediatric LTS over the past 30 years had been considerable improved, primary surgery still failed in a significant number of complex LTS cases. In some severe LTS cases combined with glottic stenosis, the primary surgery failed around 30%, even with the latest available techniques. Children with LTS usually need multiple operations, and need the tracheostomy tube for months or even years. Therefore, the etiology, clinical features, diagnosis and treatment of laryngotracheal stenosis are summarized in this paper.

[The validity and reliability of simplified Chinese version of the pediatric sleep questionnaire for screening children with obstructive sleep apnea syndrome in Beijing]

Objective: To evaluate the validity and reliability of the simplified Chinese version of pediatric sleep questionnaire (PSQ) used in screening obstructive sleep apnea syndrome (OSAS) of children in Beijing. Methods: Children with snoring who presented to the Sleep Center of Beijing Children's Hospital between August 2014 and July 2015 and healthy children were included in the study. All children underwent PSG and then were divided into OSAS group and control group based on the PSG and their guardians were asked to complete the simplified Chinese version of PSQ that was formed by both translation from PSQ and retroversion to PSQ. Structure validity evaluation included confirmatory factor analysis which used Amos structural equation model and exploratory factor analysis which used principal component analysis. Predictive validity were measured with Logistic regression model. Internal reliability and test-retest reliability were evaluated by Cronbach 's alpha coefficient and intra-class correlation coefficient (ICC), respectively. The screening efficiency was evaluated by the receiver operating characteristic curve (ROC). Results: The study included 235 children aged 3-16 years old, 145 children of them with the age of (5.8±2.1) in OSAS group and 90 children with the age of (7.7±3.3) in control group. Confirmatory factor analysis indicated most items belonging to individual factors with load coefficient ≥ 0.5. Predictive validity analysis revealed 13 items positively related to the diagnosis of OSAS (all OR>1, all P<0.05). Cronbach's alpha coefficients were respectively 0.703 (overall reliability), 0.767 (breathing factor), 0.849 (sleepiness factor) and 0.689 (behavior factor). The test-retest ICC reliability was 0.986 (PSQ), 0.991 (breathing factor), 0.727 (sleepiness factor), and 0.870 (behavior factor) with P<0.05. In receiver operating characteristic curve, the area under curve of simplified Chinese version PSQ score was 0.922 with P<0.05 and the cutoff value of PSQ score was 7 in 22 items with the sensitivity of 0.776, specificity of 0.867, positive predictive value of 0.868 and negative prediction value of 0.774. Conclusions: The simplified Chinese version of PSQ is suitable to the screen of OSAS for the children in Beijing area with good reliability and validity. It also has acceptable sensitivity and specificity for screening children with OSAS when the cutoff score is 7 points.

[Effects of noise competition on monosyllabic and disyllabic word perception in children]

Objective: The purpose of the present study was to investigate the effects of noise competition on word perception in normal hearing (NH) children and children with cochlear implantation (CI). Methods: To estimate the contribution of noise competition on speech perception, word perception in speech-shaped noise(SSN)and 4-talker babble noise(BN) with Mandarin Lexical Neighborhood Test were performed in 80 NH children and 89 children with CI. Corrected perception percentages were acquired in each group. Results: Both signal to noise ratio (SNR) and noise type influenced the word perception. In NH group, corrected percentages of disyllabic word perception in SSN were 24.2%, 55.9%, 77.1%, 85.1% and 88.9% at -8, -4, 0, 4 and 8 dB SNR, corresponding corrected percentages of monosyllabic word were 13.9%, 39.5%, 60.1%, 68.8% and 80.1%, respectively. In BN noise, corrected percentages of disyllabic word were 2.4%, 24.3%, 55.6%, 74.3% and 86.2%, corresponding monosyllabic word were 2.3%, 20.8%, 47.2%, 61.1% and 74.8%, respectively. In CI group, corrected percentages of dissyllabic word in SSN and BN at 10 dB SNR were 65.5% and 58.1%, respectively. Corresponding monosyllabic word were 49.0% and 41.0%. For SNR=5 dB, corrected percentages of disyllabic word in SSN and BN were 50.0% and 38.1%, corresponding corrected percentages of monosyllabic word were 40.8% and 25.1%, respectively. Analysis indicated that the masking effect were significantly higher in BN compared with SSN. Conclusions: Noise competition influence word perception performance significantly. In specific, the influence of noise on word perception is bigger in children with CI than in NH children. The masking effect is higher in BN noise when compared with SSN.

L6H21 prolonged rats survival after limb allotransplantation by inhibiting acute rejection

OBJECTIVE

Preventing and reducing allograft rejection play a far more important role in limb allotransplantation. We previously found L6H21 could inhibit LPS-induced (lipopolysaccharide LPS) overexpression inflammatory factors in macrophages and specifically targets to MD-2 (myeloid differential protein-2 MD-2) required for TLR4 (Toll-like receptor 4 TLR4) activation and represented an important therapeutic target in inflammatory disorders. Therefore, we evaluated the effect and explored the mechanism of L6H21 in rats' limb allograft model.

MATERIALS AND METHODS

The efficacy of L6H21 was evaluated in limb allograft rats and cyclosporine (CY-A) was used as a positive control agent. T-Lymphocyte in blood was analyzed and dendritic cells (DCs) separated from spleens using flow cytometry. ELISA was used to measure serum cytokine levels. Analysis of protein expressions was performed using Western blotting.

RESULTS

L6H21 reduced the risk of acute rejection and prolonged survival of limb allograft rats. At 3 d and 5 d post-transplant, the ratio of CD4+/CD8+ was decreased in L6H21 group. L6H21 suppressed the content of IL-1α at 7d, IL-5 and IL-10 at both 3 d and 7 d after transplantation. L6H21 decreased the protein expressions of IRF3, p-IRF3, P38, p-P38 and p-IκBα while increased IκBα expression and decreased the ratio of p-IRF3/ IRF3, p-P38/ P38, p-IκBα/IκBα correspondingly.

CONCLUSIONS

L6H21 could reduce the risk of acute rejection and prolong the survival of limb allograft rats through inhibiting the ratio of CD4+/CD8+ in blood and serum cytokine levels and suppressing protein expressions of IRF3, p-IRF3, P38, p-P38 and p-IκBα in DCs. So, it may serve as a potential candidate for the treatment of allograft rejection.

[Characteristics of sleep apnea events in non-snoring children]

Objective: To investigate the characteristics of sleep-related respiratory events in normal children and to provide normal polysomnographic parameters for diagnosing sleep-disordered breathing in children. Methods: Normal subjects between 3 and 14 years old were enrolled from 1 July 2014 to 31 December 2015 and the subjects received overnight polysomnography at the sleep center of our hospital. They were children of our hospital employees or were recruited from the communities who did not have sleep and respiratory disorders. The children were divided into preschool group (3-5 years) and school-age group (6-14 years). Apnea index (AI), obstructive apnea index (OAI), central apnea index (CAI), and mixed apnea index (MAI) were compared between the two groups. Data for continuous variables that showed normal distribution were expressed as x ±s. M(P₂₅, P₇₅) were used when data were not normally distributed. Continuous variables that showed normal distribution were compared by using an independent-sample t-test. Wilcoxon-test was performed when data exhibited non-normal distribution. Differences in categorical data were tested with Chi-square test. Pearson correlation test was applied for the correlation analysis. P<0.05 was considered statistically significant. Results: A total of 115 normal children took part in the study including 40 in preschool group and 75 in school-age group. Children in both groups had a few sleep apnea events, most of which were central apneas, accounting for 80% and 70% of the total respiratory events respectively. Central apnea index in preschool children were significantly higher than that of school-age children (P<0.001), with median of 0.6 times/h and 0.1 times/h, respectively. Median OAI of both groups were 0.0 times/h without significant difference (P=0.748). Obstructive apnea events occurred mainly in the supine position in both groups. Conclusions: Normal children may have a few apnea events in sleep that were predominantly central apnea. CAI of preschool children is significantly higher than that of school-age children. Obstructive sleep apnea is rare in normal children, and sleep apnea occurs mainly in the supine position.

An Unusual Case of a Large Subglottic Granuloma due to Foreign Body Aspiration in an 11-Year-Old Boy

Foreign bodies in subglottis are rarely seen in children. Delayed or missed diagnosis could result in serious complications. We reported a case of an 11-year-old boy, who was found to have a large subglottic granuloma due to foreign body aspiration, presented with persistent wheezing. The combined use of flexible and rigid bronchoscopy were vital to the diagnosis and treatment in this case.

[Evaluation of polysomnographic diagnostic criteria for obstructive sleep apnea syndrome in children]

Objective: To determine the appropriate criteria of obstructive sleep apnea syndrome (OSAS) in children. Method: Children with snoring and healthy children were recruited from October 2014 to September 2015. Subjects were divided into four groups based on polysomnography(PSG). Group 1: children with obstructive apnea hypopnea index(OAHI)≥1 (the OSAS criteria of the International Classification of Sleep Disorders, ICSD) but their AHI≤5 or OAI ≤1 (under the OSAS criteria of AHI>5 or OAI>1 by the American Thoracic Society, ATS); Group 2: children with OAHI<1 (the primary snoring criteria of the ICSD); Group 3: children with AHI>5 or OAI>1; and Group 4: normal children as controls. Sleep disorder scales and polysomnography parameters were compared among the four groups. Results: A total of 1 115 children were included.There were 143, 345, 529 and 98 children in each group. After adjust for age, gender and body mass index(BMI), children in group 1 had higher total sleep disorder scale score (P<0.01), as well as sub-scores for severe snoring (P<0.01), daytime behavior problem (P<0.01) and sleep related nighttime abnormality (P<0.05) compared with normal controls, and they had longer mean and longest duration of obstructive apnea and hypopnea and lower minimum oxygen saturation compared with children with obstructive AHI<1 (all P<0.05 or <0.01). Conclusion: OAHI>1 should be defined as the criteria of OSAS in children.

Bronchopleural fistula after lung ablation: Experience in two cases and literature review

BACKGROUND

Bronchopleural fistula (BPF) complicating lung tumor ablation is rare but severe. The purpose of this article was to study its characteristics and treatments.

MATERIALS AND METHODS

Two of 682 (0.3%) sessions of lung microwave ablation (MWA) were complicated with BPF and documented. Two electronic databases were searched for reported cases of BPF after lung tumor ablation. Case selection and data collection were done by 3 independent reviewers.

RESULTS

A 56-year-old man and a 61-year-old woman developed BPF after MWA and died. Thirteen cases (mean age 63.8, 61.5% male) of BPF with adequate information were identified from 8 articles. Of the 13 cases, 5 (38.5%) had pulmonary co-morbidity, 3 (23.1%) had a history of pulmonary surgery, 7 (53.8%) had a target tumor adjacent or abutting pulmonary pleura, and 6 (46.2%) developed severe infections. After chest tube placement, pleurodesis, endoscopic therapy, surgery, and other treatments, 12 were cured and 1 died of BPF and pneumonia.

CONCLUSION

BPF is a rare but severe complication of lung ablation, and the management needs a multidisciplinary and individualized treatment strategy.

RN1, a novel galectin-3 inhibitor, inhibits pancreatic cancer cell growth in vitro and in vivo via blocking galectin-3 associated signaling pathways

Galectin-3 (Gal-3) has been implicated in pancreatic ductal adenocarcinoma (PDAC), and its candidacy as a therapeutic target has been evaluated. Gal-3 is widely upregulated in tumors, and its expression is associated with the development and malignancy of PDAC. In the present study, we demonstrate that a polysaccharide, RN1, purified from the flower of Panax notoginseng binds to Gal-3 and suppresses its expression. In addition, RN1 markedly inhibits PDAC cells growth in vitro, in vivo and in patient-derived xenografts. Mechanistically, RN1 binds to epidermal growth factor receptor (EGFR) and Gal-3, thereby disrupting the interaction between Gal-3 and EGFR and downregulating extracellular-related kinase (ERK) phosphorylation and the transcription factor of Gal-3, Runx1 expression. Inhibiting the expression of Runx1 by RN1, suppresses Gal-3 expression and inactivates Gal-3-associated signaling pathways, including the EGFR/ERK/Runx1, BMP/smad/Id-3 and integrin/FAK/JNK signaling pathways. In addition, RN1 can also bind to bone morphogenetic protein receptors (BMPR1A and BMPR2) and block the interaction between Gal-3 and the BMPRs. Thus, our results suggest that a novel Gal-3 inhibitor RN1 may be a potential candidate for human PDAC treatment via multiple targets and multiple signaling pathways.

[The application of 3D simulationtemporal-bone-system for temporal bone anatomy training]

Objective:The aim of this study is to investigate the application of 3D simulation temporal-bone-system for temporal bone anatomy training.Method:3D simulation temporal-bone-system in the anatomy workshop was introduced in Beijing Children's Hospital from 2014 to 2015.Each participant was trained by cadaver dissection and 3D simulation temporal-bone-anatomy,and they also completed the questionnaires and evaluated the procedure.Then the difference was analyzed.Result:①In stage of mastoid outline,the damage of structure in 3D systemis higher than that in cadaver dissection(33.3%>22.2%),but there were no significant difference between them in the proportion of exposure.On the opening of attic,facial recess,facial nerve,the damage and the proportion of the non-exposed of cadaver dissection is higher.②There were no significant difference between them in the anatomical structures,levels of pollution,taste,cost and reproducibility(P>0.05),but in the aspect of time,relevance of CT with temporal bone,the similarity,and the force feedback,they had significant differences(P<0.01).Conclusion:3D simulation temporal-bone-system had better training effect in specialized otolaryngologist.It not only to help clinicians better understanding the temporal bone and surrounding structures,but also to emphasize the knowledge of the anatomy in temporal bone.

Psychometric testing of two new patient-reported outcome instruments for the evaluation of treatment for hypogonadism

AIM

The aim of this study was to perform psychometric testing and estimate minimal important change (MIC) of two new patient-reported outcome (PRO) instruments - Sexual Arousal, Interest and Drive Scale (SAID) and Hypogonadism Energy Diary (HED).

METHODS

New PRO instruments were administered immediately after screening (Time 1, test-retest subset only) and immediately prior to both randomisation (Time 2) and end-point (Time 3) to men participating in a randomised clinical trial comparing the effect of testosterone solution 2% (TS) and placebo on serum total testosterone. Psychometric analyses included reliability, validity and responsiveness. Total scores for both PRO instruments were transformed to a 0-100 scale.

RESULTS

Study participants (n = 694) were 80% age ≤ 65 years, 79% White, with mean baseline testosterone = 202 ng/dl. Clinicians identified 86% subjects as having low sex drive, 86% with low energy and 76% with both symptoms. Reliability analyses for SAID and HED yielded reliability coefficients > 0.70. SAID scores discriminated between men having low sex drive (n = 553) and those who did not (n = 80) (34.5 vs. 42.8, p < 0.001). HED scores discriminated between men having low energy (n = 541) and those who did not (n = 64) (48.9 vs. 60.2, p < 0.001). In the men randomised to TS (vs. placebo), SAID and HED detected effect sizes of 0.61 (vs. 0.39) and 0.68 (vs. 0.48), respectively. MIC estimates for SAID and HED were approximately 10 and 8, respectively.

CONCLUSIONS

This study provided evidence of the reliability, validity and responsiveness of SAID and HED as measures of sex drive and energy, respectively, making them potentially useful for evaluation of hypogonadal treatment.

An instrument to measure mechanical up-conversion phenomena in metals in the elastic regime

Crystalline materials, such as metals, are known to exhibit deviation from a simple linear relation between strain and stress when the latter exceeds the yield stress. In addition, it has been shown that metals respond to varying external stress in a discontinuous way in this regime, exhibiting discrete releases of energy. This crackling noise has been extensively studied both experimentally and theoretically when the metals are operating in the plastic regime. In our study, we focus on the behavior of metals in the elastic regime, where the stresses are well below the yield stress. We describe an instrument that aims to characterize non-linear mechanical noise in metals when stressed in the elastic regime. In macroscopic systems, this phenomenon is expected to manifest as a non-stationary noise modulated by external disturbances applied to the material, a form of mechanical up-conversion of noise. The main motivation for this work is for the case of maraging steel components (cantilevers and wires) in the suspension systems of terrestrial gravitational wave detectors. Such instruments are planned to reach very ambitious displacement sensitivities, and therefore mechanical noise in the cantilevers could prove to be a limiting factor for the detectors' final sensitivities, mainly due to non-linear up-conversion of low frequency residual seismic motion to the frequencies of interest for the gravitational wave observations. We describe here the experimental setup, with a target sensitivity of 10(-15) m/Hz in the frequency range of 10-1000 Hz, a simple phenomenological model of the non-linear mechanical noise, and the analysis method that is inspired by this model.