Clinical outcomes of various types of revision surgeries after unicompartmental knee arthroplasty failure

PURPOSE

The advantages of unicompartmental knee arthroplasty (UKA) have led to the procedure being increasingly performed worldwide. However, revision surgery is required after UKA failure. According to the literature review, the choice of implant in revision surgery remains a debatable concern. This study analyzed the clinical results of different types of prostheses used in treating failed UKA.

MATERIALS AND METHODS

This is a retrospective review of 33 failed medial UKAs between 2006 and 2017. Demographic data, failure reason, types of revision prostheses, and the severity of bone defects were analyzed. The patients were classified into three groups: primary prosthesis, primary prosthesis with a tibial stem, and revision prosthesis. The implant survival rate and medical cost of the procedures were compared.

RESULTS

A total of 17 primary prostheses, 7 primary prostheses with tibial stems, and 9 revision prostheses were used. After a mean follow-up of 30.8 months, the survival outcomes of the three groups were 88.2%, 100%, and 88.9%, respectively (P = 0.640). The common bone defect in tibia site is Anderson Orthopedic Research Institute [AORI] grade 1 and 2a (16 versus 17). In patients with tibial bone defects AORI grade 2a, the failure rates of primary prostheses and primary prostheses with tibial stems were 25% and 0%, respectively.

CONCLUSIONS

The most common cause for UKA failure was aseptic loosening. The adoption of a standardized surgical technique makes it easier to perform revision surgeries. Primary prostheses with tibial stems provided higher stability, leading to a lower failure rate due to less risk of aseptic loosening in patients with tibial AORI grade 2a. In our experience, we advise surgeons may try using primary prostheses in patients with tibial AORI grade 1 and primary prostheses with tibial stems in patients with tibial AORI grade 2a.

Nontuberculous mycobacteria peri-prosthetic joint infection: An outcome analysis for two stage revision arthroplasty

PURPOSE

Nontuberculous mycobacteria periprosthetic joint infection (NTMPJI) is a rare complication of hip or knee joint arthroplasty. The experience for outcomes of NTMPJI treatment is still limited. The objective of this study was to investigate the outcome of hip or knee nontuberculous mycobacteria periprosthetic joint infection following treatment with two-stage exchange arthroplasty.

MATERIAL AND METHODS

From 1995 to 2020, 12 patients with NTMPJI were treated with two-stage exchange arthroplasty at our institution. We collected and analyzed variables including demographic data, comorbidity, microbiological data, treatment outcome and antibiotic formula in bone cement.

RESULTS

Mycobacterium abcessus (n = 6) and Mycobacterium chelonae (n = 2) constitute the majority of the cases. Five patients had early-onset PJIs and the other seven patients were late onset. The success rate of two-stage exchange arthroplasty was 66.7% (8 of 12). Three patients experienced infection relapse, and one patient had soft tissue compromise complication. Post-operative antibiotic therapy may not improve the success rate (4 of 6 cases, 66.7%). Based on in vitro study, the most commonly used effective antibiotic in bone cement spacer for nontuberculous mycobacteria was amikacin.

CONCLUSIONS

nontuberculous mycobacteria is a rare cause of PJIs and should be suspected especially in relatively immunocompromised patients. Resection arthroplasty with staged reimplantation is the preferred approach. Prolonged post-operative antibiotic therapy before reimplantation may not improve the success rate. Delayed revision surgery may not be needed and can be performed once C-reactive protein level is normal after a drug holiday.

Surgical treatment of femoral head fractures

Background

Femoral head fractures (FHF) are uncommon and generally caused by high-energy injuries. Surgical reduction with stable fixation of large fragments is believed to have the best outcomes. This retrospective study intended to report outcomes with surgical treatment at our institution and tried to establish treatment algorithm.

Methods

Through the 6-year period (2003–2008), 35 FHF in 35 consecutive patients (average, 30 years) were surgically treated. All FHF were caused by high-energy trauma. Patients' general condition was stabilized first and hip dislocation was manually reduced immediately. Definite fracture treatment was scheduled after admission for an average of 2.9 days (0.3–11 days). Pipkin classification was used as the treatment guide and open reduction with internal fixation was performed in all 35 FHF.

Results

These FHF included 21 type I, 7 type II, 3 type III, and 4 type IV fractures. The hip joint had been approached by either an anterior or posterior route depending on the individual surgeon. Internal fixation with screws was performed for all 35 FHF. The average admission was 13.8 days (range, 2–35 days). Thirty patients (86%, 30/35) were followed for an average of 3.3 years (at lease 6 months) and all 30 FHF healed. Avascular necrosis of the femoral head was found in 23% (7/30) patients and six patients were converted to hip arthroplasty for developing advanced stages of avascular necrosis. Heterotopic ossification occurred in 43% (13/30) patients. However, only one patient had range of motion limitation. Besides, one patient had moderate hip osteoarthritis.

Conclusions

FHF are uncommon and generally caused by high-energy injuries. Fracture healing can be attained in all femoral head fractures by using open reduction and screw fixation. Our results by using conventional approaches were associated with high complication rates. Further endeavor to improve the outcome should be taken.

LncRNA HOXA11-AS promotes migration and invasion through modulating miR-148a/WNT1/β-catenin pathway in gastric cancer

Increasing researches have focused on the biological functions of long noncoding RNAs (lncRNAs) in human cancers. HOXA11-AS, a widely known lncRNA, has been confirmed to be involved in the progression of several cancers, including gastric cancer (GC). Whereas, the detailed mechanism of this lncRNA in GC remains to be further illuminated. The abundances of HOXA11-AS, miR-148a and WNT1 in GC tissues and cell lines were examined by qRT-PCR. Clinicopathological and Kaplan-Meier survival analyses were determined to explore the relationship between HOXA11-AS expression and outcomes of patients. Transwell assay was performed for the evaluation of cell migration and invasion. Bioinformatics, dual-luciferase reporter and RNA immunoprecipitation assays were employed to analyze the correlation between HOXA11-AS and miR-148a or miR-148a and WNT1. The protein levels of WNT1 and β-catenin were assessed by western blot assay. Results showed that HOXA11-AS and WNT1 expression levels were upregulated, while miR-148a level was downregulated in GC tissues and cell lines relative to matched controls. Elevated expression of HOXA11-AS was associated with increased tumor size, lymph node metastasis, advanced TNM stage, as well as reduced survival of GC patients. HOXA11-AS induced migration and invasion of GC cells through serving as a molecular sponge for miR-148a. Furthermore, miR-148a inactivated WNT1/β-catenin signaling pathway via directly targeting WNT1. HOXA11-AS increased WNT1/β-catenin pathway activity, which was abolished by miR-148a overexpression in GC cells. In conclusion, overexpression of HOXA11-AS contributed to migration and invasion of GC cells via activation of WNT1/β-catenin signaling pathway through repressing miR-148a, providing a prospective therapeutic target for GC.

[Clinical characteristics of Kaposiform lymphangiomatosis: a report of 8 cases]

Objective: To investigate the clinical symptoms, treatment intervention and prognosis of Kaposiform lymphangiomatosis(KLA). Methods: Medical information and clinical characteristics data of 8 KLA patients who were admitted to Department of Pediatric Surgery of West China Hospital of Sichuan University from January 2016 to February 2019 were retrospectively reviewed and analyzed. There were 5 males and 3 females with age of 5.8 years old (from 8 months to 29 years old). Results: The lesions in all patients were diffusely distributed. In all 8 patients, the lung and mediastinum were involved with different degrees. Three cases had lesions involving pelvic and abdominal organs. Three cases had lesions involving bones. One case simultaneously involved pelvic and abdominal organs, and 1 case was involved laryngeal and neck. The clinical characteristics were mainly respiratory symptoms. In the laboratory tests, 6 patients had different degrees of thrombocytopenia (minimum 3 × 10(9)/L), and 4 patients had severe fibrinogen reduction (minimum 0.42 g/L). Three patients had prolonged activated partial thromboplastin time (up to 64.2 seconds) and 3 patients had prolonged prothrombin time (up to 18.6 seconds). After surgery (including thoracotomy, chest tube, pericardiocentesis, splenectomy) and empiric medicine therapy (vincristine, sirolimus and corticosteroid), the symptoms improved in 1 case, 2 cases died of complications, 2 cases were stable and 3 cases progressed up to February 2019. Conclusions: KLA is a rare disease that should be differentiated from other types of vascular diseases. Currently, there is no consensus treatment guidelines exist. Accurate diagnosis in KLA can be a challenge. The situation in patients with KLA is prone to rapid deterioration and progress. Future research efforts should seek to develop target-specific drugs for KLA.

Simultaneous removal of aqueous Zn2+, Cu2+, Cd2+, and Pb2+ by zeolites synthesized from low-calcium and high-calcium fly ash

In this study, zeolites were synthesized from low-calcium (LCZ) and high-calcium (HCZ) fly ash, respectively. Subsequently, the zeolites were tested for their removal effectiveness for four aqueous cations, namely, Zn²⁺, Cu²⁺, Cd²⁺, and Pb²⁺, as a function of contact time, pH value, adsorbent dosage, and initial concentration of heavy metals. Both zeolites were characterized by X-ray diffraction, X-ray fluorescence spectrometry, scanning electron microscopy, specific surface area, and cation exchange capacity. The results show that HCZ mainly consists of an unnamed zeolite (Na₆[AlSiO₄]₆·4H₂O), whereas LCZ mainly consists of faujasite-type zeolite. The optimum sorption conditions were pH = 6.0; adsorbent dosage = 1.0 g·L^-1; temperature = 25 °C; contact time = 100 min; and initial heavy metal concentration = 100 mg·L^-1. The sorption kinetics of the four aqueous cations on both LCZ and HCZ followed the pseudo-second-order kinetic model, and the sorption isotherm data fitted well with the Langmuir isotherm model. For LCZ, the maximum adsorption capacities of Zn²⁺, Cu²⁺, Cd²⁺, and Pb²⁺ were 155.76, 197.86, 123.76, and 186.22 mg·g^-1, respectively. For HCZ, the values were 154.08, 183.15, 118.91, and 191.94 mg·g^-1, respectively. The zeolites were regenerated by NaCl solution (1 mol·L^-1) and showed high removal efficiency. In conclusion, zeolites produced by fly ash are promising materials for removing Zn²⁺, Cu²⁺, Cd²⁺, and Pb²⁺ from wastewater.

[Clinical value of fluorescence in situ hybridization positive of exfoliated urothelial cells in urothelial carcinoma]

OBJECTIVE

To analyze the clinical pathologic characteristics of cases with fluorescence in situ hybridization (FISH) positive of exfoliated urothelial cells, so as to evaluate the clinical utility of FISH in the diagnosis of urothelial carcinoma (UC).

METHODS

A total of 271 cases of FISH positive in Department of Urology of Peking University First Hospital from Apr. 2012 to Sep. 2015 were recruited in this study. Retrospective analysis was made on their clinical data. For FISH analysis, labeled probes specific for chromosomes 3, 7, 17, and the p16 (9p21) gene were used to assess chromosomal abnormalities indicative of malignancy. The positive predict values (PPV) of all the techniques were analyzed.

RESULTS

Of the 271 patients, 207 cases were UC, 7 cases were non-UC, and 57 cases were benign diseases. The PPV of FISH in detecting UC was 76.4%, while the 95% confidence interval (CI) 71.3% to 81.5%. In the cohort of FISH positive, this value was similar to that of urinary cytology (PPV 86.8%, 95% CI: 78.5%-95.0%). The PPV of FISH was lower than that of cystoscopy and ureteroscopy (PPV 96.1%, 95% CI: 91.7%-100.0%). There were significant differences between this study and the PPV of FISH reported abroad (PPV 53.9%, χ²=33.048, P<0.001). Of all the UC with FISH positive, bladder cancer showed an earlier pathological stage versus renal pelvic carcinoma and ureteral carcinoma, with significance (χ²=5.894, P=0.015, and χ²=13.601, P<0.001, respectively). However, no difference was found in the size, pathological stage and pathological grade of tumors between the urinary cytology positive group and the urinary cytology negative group. The rate of high-grade UC in ureteral carcinoma of FISH positive was 92.3%, much higher than that of ureteral carcinoma reported domestically.

CONCLUSION

The PPV of FISH in detecting UC is higher relatively, with a better clinic value for Chinese patients. The ureteral carcinoma with FISH positive obtains a higher pathological grade, which is of great guiding significance for UC.

[Immune response to one booster dose of inactivated hepatitis A vaccine in college students]

Objective: To evaluate the safety and immunogenicity of one booster dose of inactivated hepatitis A vaccine in young adults. Methods: The subjects were selected from participants in the clinical trial of immunogenicity of inactivated and attenuated live hepatitis A vaccine in young adults. Eligible subjects were those who had received one dose of inactivated or attenuated hepatitis A vaccine, could be contacted and were sero-negative before primary vaccination. All qualified subjects were immunized with one booster dose of inactivated hepatitis A vaccine. The blood samples were collected before booster dose vaccination and 28 days after the immunization. Anti-HAV antibody titer ≥20 mIU/ml was considered to be sero-protected against hepatitis A virus. Results: The GMCs in the inactivated HAV vaccine group and attenuated live vaccine group before booster dose vaccination were 70.80 mIU/ml and 50.12 mIU/ml, respectively, and the sero-protection rates were 94.7% and 65.0%, respectively. After the vaccination of the booster dose, the sero-protection rates in both groups were 100.0%, and the GMCs were 2 816.09 mIU/ml and 2 654.55 mIU/ml, respectively. Conclusion: The GMCs and sero-protection rates of anti-HAV antibody in young adults declined after three years of the primary vaccination. However, the higher GMC and sero-protection rate were observed in the inactivated vaccine group than in the attenuated live vaccine group. Significant increases of GMC levels were observed in both groups after one booster dose vaccination.

Compost feedstock characteristics and ratio modelling for organic waste materials co-composting in Malaysia

In Malaysia, large amounts of organic materials, which lead to disposal problems, are generated from agricultural residues especially from palm oil industries. Increasing landfill costs and regulations, which limit many types of waste accepted at landfills, have increased the interest in composting as a component of waste management. The objectives of this study were to characterize compost feedstock properties of common organic waste materials available in Malaysia. Thus, a ratio modelling of matching ingredients for empty fruit bunches (EFBs) co-composting using different organic materials in Malaysia was done. Organic waste materials with a C/N ratio of < 30 can be applied as a nitrogen source in EFB co-composting. The outcome of this study suggested that the percentage of EFB ranged between 50% and 60%, which is considered as the ideal mixing ratio in EFB co-composting. Conclusively, EFB can be utilized in composting if appropriate feedstock in term of physical and chemical characteristics is coordinated in the co-composting process.

The value of Doppler waveform analysis in predicting major lower extremity amputation among dialysis patients treated for diabetic foot ulcers

AIMS

This study examined the predictors for lower extremity amputation (LEA) in patients with diabetic foot ulcers according to kidney function and, in the case of dialysis patients, specifically evaluated the vasculature with the ankle-brachial index (ABI) and Doppler waveforms.

METHODS

Among 658 diabetic patients admitted to the Diabetic Foot Care Center, 286 had an estimated glomerular filtration rate (eGFR)≥ 60 ml/min per 1.73 m(2), 275 had an eGFR<60, and 97 patients were under maintenance dialysis. All clinical variables were analyzed. A specialist retrospectively reviewed Doppler images of 78 of the patients in dialysis to evaluate peripheral arterial disease.

RESULTS

Forty-two percent of patients with eGFR<60 presented with ABI≤0.90. For ABI values>1.40, the proportion of dialysis patients (31.3%) was greater than the proportion of patients with eGFR<60 (5.3%). Wagner wound classifications, reduced serum albumin levels, and low ABI values were the predictors for major LEA among patients in the non-dialysis groups. Nevertheless, these indicators were not predictive of the risk of amputation in diabetic patients on dialysis. The presence of poor monophasic waveforms in the dorsalis pedis artery or posterior tibial artery served as an independent predictor (odds ratio: 7.61; P=0.008) for major LEA among dialysis patients. The sensitivity and specificity were 88.0% and 59.6%, respectively.

CONCLUSIONS

Poor monophasic Doppler waveforms of below-the-knee arteries, commonly found among dialysis patients in treatment for diabetic foot ulcers, can serve as an independent predictor for major LEA.

A novel application of an anaerobic membrane process in wastewater treatment

The applications of membrane processes in anaerobic biological wastewater treatment still have some limitations due to severe membrane scaling and fouling, although they have been proven to achieve superior COD removal and biomass retention. An innovative anaerobic membrane process for wastewater treatment was conducted to control the membrane scaling problems. The process comprises an anaerobic reactor, an aerobic reactor, and a membrane separation tank. Anaerobic sludge from a full-scale UASB reactor treating food wastewater was inoculated to anaerobic and aerobic reactor to purify synthetic wastewater consisting of glucose and sodium acetate. The anaerobic reactor was operated in a sludge bed type without three-phase separator. The aerobic reactor can eliminate residual organics from the anaerobic reactor effluent using facultative microorganisms. To provide solid-liquid separation, hollow fiber ultrafiltration module was submerged in the separation tank. The results clearly show that the anaerobic membrane process combined methanogenic and aerobic COD reduction is a stable system. No fatal scaling was found after two months of operation even without chemical cleaning for the membrane. It was also found that inorganic precipitates formed in the aerobic reactor were reduced due to CO2 stripping in aerobic reactor. Another important finding was that the inorganic precipitates were entrapped into facultative aerobes floc. The ash/SS ratio of aerobes floc increased from 0.17 to 0.55 after 50 days of operation, which confirms this phenomenon. Based on our investigation, the new process can control scaling effectively to extend the membrane application in anaerobic treatment.

Oral testosterone administration detected by testosterone glucuronidation measured in blood spots dried on filter paper

BACKGROUND

Blood sampling is not a common practice for sports drug testing. Our aim was to investigate whether dried blood spots on filter paper could be an alternative to plasma samples for monitoring steroid profiles in dope testing.

METHODS

We collected dried blood spots and plasma from six healthy Caucasian subjects after an oral 120-mg dose of testosterone undecanoate (TU). Nonconjugated testosterone, testosterone glucuronide (TG), androsterone glucuronide (AG), and etiocholanolone glucuronide (EtG) were measured by gas chromatography-mass spectrometry in both matrices. 17alpha-Hydroxyprogesterone (17alphaOHP) and luteinizing hormone (LH) also were measured in the plasma samples. For comparison, similar measurements were done on samples obtained from the same subjects given 25 mg of testosterone propionate (TP) plus 110 mg of testosterone enanthate (TE) intramuscularly after a wash-out period.

RESULTS

After oral TU intake, TG, AG, and EtG increased sharply, whereas nonconjugated testosterone did not change significantly. Results on dried blood spots correlated well with those on plasma. The TG/testosterone ratio in blood or plasma was verified to be a sensitive and specific marker (significantly increased for up to 8 h after intake; P <0.05) for oral TU intake but not for intramuscular administration of TP plus TE. Little suppression of plasma LH and 17alphaOHP was observed after a single oral dose of TU. One subject did not show a significant increase of blood TG after oral TU intake.

CONCLUSIONS

The measurement of glucuronide conjugates in blood and plasma samples is relevant for sports drug testing when analyzing the steroid profile. Dried blood spots collected on filter paper are a suitable alternative to plasma for detecting testosterone abuse.

Hair analysis and detectability of single dose administration of androgenic steroid esters

Detection of anabolic steroids in hair samples has been possible only in fatal cases or in cases of high-continuous dosages. In order to verify the possibility of detecting an acute administration, a sensitive and specific assay has been developed for the simultaneous determination of testosterone, nandrolone and some of their esters in hair. The analytes were extracted from finely cut hair with methanol-trifluoroacetic acid overnight. After the incubation, the mixture was evaporated to dryness, redissolved and extracted with hexane. The dried organic layer was silanised and analysed by GC-MS and GC-MS-MS. A sensitivity of at least 20 pg injected was obtained for all the analytes. In guinea pigs treated with a single intramuscular dose of 10 mg/kg nandrolone decanoate, neither nandrolone decanoate nor nandrolone were found in hair collected after 13 days, while both compounds were clearly detectable after four repeated doses (each dose every 3-4 days) of 20 mg/kg nandrolone decanoate. Neither nandrolone decanoate nor nandrolone could be detected in hair from a male healthy volunteer 1 month after treatment with 50 mg nandrolone decanoate, while his urine still tested highly positive for the main nandrolone metabolite (> 100 ng/ml). Testosterone esters could not be detected in hair of healthy subjects collected respectively 3, 2 and 1 month after a single intramuscular administration of 250 mg testosterone enanthate (five subjects), a single intramuscular coadministration of 25 mg testosterone propionate plus 110 mg testosterone enanthate (one subject), or a single oral administration of 120 mg testosterone undecanoate (three subjects). Otherwise, hair analysis revealed an increase of testosterone concentration corresponding to the period of treatment. Analysis of blood and urine samples confirmed the absorption of those compounds. At the sensitivity achieved by the present method, no detection of nandrolone, nandrolone decanoate nor testosteron esters in hair seems to be obvious after a single dose administration.

[Investigation on in vivo metabolism of n-butyl phthalide]

A GC-MS method for the investigation on the metabolism of n-butyl phthalide (NBP) is described. After oral administration of NBP to rats, urine was collected, hydrolyzed with beta-glucuronidase, extracted and concentrated for TMS derivatization, and then analyzed by GC-MS. HBP and its four oxidative metabolites were determined in 0-24 h, 24-48 h rat urine. The mass spectra of the metabolites and their derivatives were presented and the in vivo metabolic pathway was discussed.

[Investigation on in vivo metabolism of 6-methoxy n-butyl phthalide]

A GC-MS method for the investigation on the metabolism of 6-methoxy n-butyl phthalide (MBP) is described. After oral administration of MBP, the rat urine sample was collected, hydrolyzed with beta-glucuronidase, extracted and concentrated for TMS derivatization, and then analyzed by GC-MS. MBP and its six oxidative metabolites were determined in the 0-24 h rat urine sample. The mass spectra of the metabolites and their derivatives were presented and the in vivo metabolic pathway was discussed.

Metabolism of 6-chloro n-butyl phthalide in rat

6-Chloro n-butyl phthalide (CBP) was orally administered to healthy, male Wistar rats pretreated with or without 3-methylcholanthrene (3-MC) by a single dose of 150 mg/kg, and urine samples were collected for 0-24 h. The urine sample was hydrolyzed with beta-glucuronidase, extracted and concentrated for TMS derivatization, and analysed on a GC-MS system for identification of CBP metabolities. Mass spectral analysis suggests that 7 CBP metabolites were present in the urine sample, and similar metabolism patterns were viewed in rats with or without pretreatment with 3-MC. Four main metabolites of CBP in rat urine were identified as alpha-beta oxolate, beta-gamma oxolate, beta-hydroxylate and gamma-hydroxylate, based on their chromatographic and mass spectral properties. Two hydroxylates have been previously identified in CBP metabolism by rat liver microsomes. The other two metabolites with higher polarity were tentatively identified as dihydroxylation products on the n-butyl side chain by the mass spectra of their TMS derivatives. One minor metabolite was found by the isotopic effect of chlorine, but its specific structure was undetermined. The difference between in vivo and in vitro metabolic profiles of CBP is also discussed.

[Studies on metabolism of 6-methoxy butyl phthalide by rat liver microsomes]

The in vitro biotransformation of 6-methoxy butyl phthalide (MBP) by phenobarbital induced rat liver microsomes was investigated by GC/MS and GC/MS with TMS derivatization. Three major metabolites of MBP were identified as 3-OH-MBP, 6-OH-butyl phthalide and gamma-OH-MBP. A less polar metabolite was tentatively identified as an epoxidation product.

[Studies on metabolism of 6-chloro butyl phthalide by rat liver microsomes]

The in vitro metabolism of 6-chloro-butyl phthalide (CBP) was studied by rat hepatic microsomes. The constitution of the incubation system was optimized and a RP-HPLC-DAD method was developed for the on-line analysis of CBP and its metabolites. The difference of the metabolism profiles of CBP by rat liver microsomes induced by phenobarbital (PB) and 3-methylcholanthrene (3-MC) was also compared. TLC, column chromatography and preparative HPLC were used for the isolation and purification of the major metabolites and they were identified as (R/S) gamma-hydroxy-CBP and (R/S) beta-hydroxy-CBP by UV, NMR and MS.

Cross-language influence on the production of Mandarin /f/ and /x/ and Taiwanese /h/ by native speakers of Taiwanese Amoy

The present study examines the patterns of interference between a first (here, Amoy) and second language (here, Mandarin) by comparing the production of a Mandarin phone [f] (a 'new' phone) with another Mandarin phone [x] (which is 'similar' to an Amoy phone [h]) by three groups of native Amoy subjects differentiated by proficiency in Mandarin. Their Mandarin production was also compared to that of Mandarin monolinguals. The spectrum of each consonant was analyzed to show the frequency range and energy of the fricative. In general, native Amoy speakers interpreted Mandarin /f/ and /x/ in terms of their first language phones [hw], but showed different patterns of interference for different proficiency levels. The least proficient simply substituted the Amoy phones for the Mandarin. More proficient speakers could approximate the Mandarin monolingual phonetic norm for the 'new' phone [f] more accurately than for the 'similar' phone [x]. The most proficient showed little Amoy-to-Mandarin interference on even the 'similar' phone [x]. On the other hand, the most proficient showed some interference from Mandarin /x/ on their Amoy production.