[Effectiveness of influenza vaccination for school-age children in preventing school absenteeism in Shenzhen: an empirical study].

Objective: To assess the impact of vaccination at school and influenza vaccination rates among school-age children on school absenteeism in Shenzhen. Methods: The study subjects were primary school students in Shenzhen. School absenteeism panel database from December 2017 to June 2020 of 286 primary schools in Shenzhen was merged with vaccination rates and organizational patterns (i.e., vaccination at school vs. non-school) data of 9 districts in Shenzhen after influenza vaccination for children. The outcome was the number of school absenteeism. The treatment and control groups were distinguished by organizational patterns and district vaccination rates. Difference-in-Difference (DiD) Poisson regressions were used to analyze the effectiveness of vaccination at school and higher vaccination rates. Besides, a robustness test was performed on the regression results. Results: Poisson regression analysis and robustness test of regression results showed that vaccination at school and higher vaccination rates effectively reduced the risk of school absenteeism, with effectiveness against absenteeism of 32.6% (95%CI: 17.0%-45.3%, P<0.01) and 53.0% (95%CI: 42.1%-61.8%, P<0.01), respectively. Conclusion: A free influenza vaccination program for school-age children in Shenzhen and prioritizing school-based vaccination may be an effective measure to reduce the risk of school absenteeism.

Effect of CTCs and INHBA level on the effect and prognosis of different treatment methods for patients with early breast cancer.

OBJECTIVE: We aimed at investigating the changes in the number of circulating tumor cells (CTCs) in patients with early breast cancer (BCa) before and after different treatments, and the influence of INHBA expression on patients' therapy efficacy and prognosis prediction was also evaluated. PATIENTS AND METHODS: Treatment plans were formulated based on patient's condition and willingness. 160 patients with early BCa were divided into trastuzumab adjuvant group (80 cases) and surgery group (80 cases). The correlation between the number of CTCs and Inhibin, beta A (INHBA) level was assessed by Spearman correlation analysis. The cumulative survival curve was depicted using Kaplan-Meier method to evaluate the prognosis of patients in different groups. RESULTS: The number of detected CTCs and INHBA expression in the two groups were both reduced as compared with those before chemotherapy. After 3 months of treatment, CTCs and INHBA level in the surgical group were detected lower than those in the trastuzumab group. The number of CTCs was positively correlated with INHBA level. The overall survival rate of patients in the surgery group was remarkably higher than those in the adjuvant trastuzumab group. CONCLUSIONS: The CTCs in the peripheral blood of patients with early BCa showed a great relevance to INHBA expression, which may thus serve as predictors of treatment effect and prognosis of BCa patients in early stage. Meanwhile, we demonstrate that surgery should be the first choice for early BCa patients after chemotherapy.

[Characteristics and clinical significance of serum D-dimer level before and after delivery in women with advanced maternal age].

Objective: To explore the characteristics of serum D-dimer level before and after delivery in women with advanced maternal age (VTE), and to assess the value of the characteristics for the diagnosis of venous thromboembolic disease. Methods: The objects were 785 puerperae with advanced maternal age (AMA) who experienced delivery in Women's Hospital, Zhejiang University School of Medicine during 1(st) Jan 2017 to 31(st) Dec 2017, and 327 puerperae with appropriate maternal age as controls were randomly selected from puerperae who gave birth in the same period. Their serum D-dimer levels before and after delivery were evaluated, and AMAs with high-level postnatal serum D-dimer were specially observed for the prognosis. Besides, puerperae complicated with VTE were retrieved from the medical database during 2014-2018, and their clinical characteristics and dynamic variation of serum D-dimer levels were analyzed. Result: The significant difference of D-dimer levels neither before nor after delivery was not observed between AMAs and controls (antenatal: 1.64(1.19, 2.29) mg/L vs 1.53(1.04, 2.23) mg/L, and postnatal: 2.70(1.71, 2.97) mg/L vs 2.63(1.17, 4.13) mg/L, P<0.05 for both; None of AMAs with high-level serum D-dimer after delivery were complicated with VTE, and most of their serum D-dimer levels decreasedsharply with in four postnatal days (the average decrease was 9.2(7.69,12.74) mg/L, and 96.2% of the sepuerperae's decrease was more than 50%). Eight puerperae complicated with VTE were found in the database from 2014 to 2018, among which five were AMAs. The eight puerperae all received a B ultrasound because of the discomfort of lower limbs or abnormal variation of serum D-dimer levels (a slow decrease or an increase trend), so that a diagnosis of VTE was established; besides, the diagnosis or symptoms all emerged in the 3(rd) to 5(th) day after caesarean. Conclusions: The factor of advanced maternal age has little influence on the serum D-dimer level before or after delivery among pregnant women. It is not a single detection for serum D-dimer level, but the intensive monitoring of clinical symptoms and dynamic change of serum D-dimer level, that helps early diagnosis of VTE.

Molecular identification and biological characteristic analysis of an Apiotrichum mycotoxinivorans (formerly Trichosporon mycotoxinivorans) strain isolated from sputum specimens of a pediatric patient with pneumonia.

Apiotrichum mycotoxinivorans (formerly Trichosporon mycotoxinivorans) has long been used to degrade fungal toxins in livestock feed. However, clinic reports about this type of fungus are rare. In this study, we report the morphology, biochemistry, and molecular characteristics of an A. mycotoxinivorans strain isolated from a pediatric patient with congenital ventricular septal defect and pneumonia. A female patient, 26 months old, presented with congenital ventricular septal defect. Pulmonary infection symptoms were observed after the patient received cardiac repair surgery. Sputum bacterial and fungal cultures were positive for Elizabethkingia anophelis and a fungus, which was not readily identifiable using biochemical identification, or MALDI-TOF MS analysis. The strain was finally identified as A. mycotoxinivorans using amplification and sequencing of the D1/D2 region of 26S rDNA, ITS, and IGS1. Antifungal susceptibility test results suggested that fluconazole or voriconazole may be an appropriate choice for antifungal therapy. A biodegradability of ochratoxin A was considered as a characteristic of the fungal strain. Our results support the existing evidence that A. mycotoxinivorans is an opportunistic pathogen for human beings. Nucleic acid analysis allows for the accurate identification of the species in instances where conventional identification methods such as biochemical testing and MALDI-TOF MS may be unsuccessful.

Long non-coding RNA CCAT1 promotes the migration and invasion of prostate cancer PC-3 cells.

OBJECTIVE: To investigate the effect of long non-coding RNA CCAT1 on the proliferation, migration, and invasion of prostate cancer PC-3 cells. PATIENTS AND METHODS: The expression of CCAT1 was detected by Real-time PCR. The effect of CCAT1 down-regulation on the proliferation of PC-3 cells was observed by MTT assay. The regulatory of CCAT1 low-expression on the migration ability of PC-3 cells was investigated by transwell assay. The influence of decreased CCAT1 on the invasion ability of PC-3 cells was detected by  Matrigel invasion assay. RESULTS: Increased CCAT1 was significantly related to lymph node metastasis in prostate cancer. Low-expression of CCAT1 could suppress cell proliferation. Knockdown of CCAT1 inhibited the migration of PC-3 cells. Down-regulation of CCAT1 attenuated the invasion of PC-3 cells. CONCLUSIONS: CCAT1 promoted the growth and the metastasis of prostate cancer. Our findings might provide a potential target for the diagnosis and treatment of prostate cancer.

Nd3+/Yb3+ cascade-sensitized single-band red upconversion emission in active-core/active-shell nanocrystals.

Lanthanide-doped upconversion nanomaterials (UCNMs) have promoted extensive interest for its biological research and biomedical applications, benefiting from low autofluorescence background, deep light penetration depth, and minimal photo-damage to biological tissues. However, owing to the 980 nm laser-induced overheating issue and the attenuation effect associated with conventional multi-peak emissions, the usage of UCNMs as fluorescent bioprobes is still limited. To address these issues, an effective strategy has been proposed to tune both the excitation and emission peaks of UCNMs into the first biological window (650 âˆ¼ 900 nm), where the light absorption by water and hemoglobin in biological tissues is minimal. Based on the Nd3+/Yb3+ cascade-sensitized upconversion process and efficient exchange-energy transfer between Mn2+ and Er3+ in conjunction with the active-core@active-shell nanostructured design, we have developed a new class of upconversion nanoparticles (UCNPs) that exhibit strong single-band red emission upon excitation of an 808 nm near-infrared laser. Hopefully, the well-designed KMnF3:Yb/Er/Nd@ KMnF3:Yb/Nd core-shell nanocrystals will be considered a promising alternative to conventionally used UCNPs for biolabeling applications without the concern of the overheating issue and the attenuation constraints.

Mesangial proliferative lupus nephritis with podocytopathy: a special entity of lupus nephritis.

Mesangial proliferative lupus nephritis may coexist with podocytopathy, but its clinical-morphological features, treatment response and outcomes have not been compared with mesangial proliferative lupus nephritis without podocytopathy. In this study, 125 biopsies of lupus nephritis patients showing mesangial proliferation with mesangial immune deposits were collected and divided into podocytopathy group (defined as podocyte foot process effacement (FPE) >50% with nephrotic syndrome (NS)) and mesangial group (FPE ≤50%, or FPE >50% without NS). Mesangial proliferation and tubular- interstitial lesions were semi-quantitatively analyzed. We found that the incidence of renal involvement as the onset symptoms ( P < .001), nephrotic syndrome ( P < .001), acute kidney injury ( P < .001), the degree of acute tubular- interstitial lesions ( P < .001), and renal relapse (51.6% vs. 23.7%, P = .005) were significantly higher in the podocytopathy group than in the mesangial group. In contrast, the incidence of arthritis ( P < .001), fever ( P = .042), low serum C4 ( P = .008) and hematuria ( P = .033) was significantly lower in the podocytopathy group than in the mesangial group. No patients developed end stage renal disease or death during a median follow-up of 64 (interquartile range (IQR) 37-103) months in the podocytopathy group and 53 (IQR 30-83) months in the mesangial group. In conclusion, mesangial proliferative lupus nephritis with and without podocytopathy should be subdivided into two separate classes of lupus nephritis.

Long non-coding RNA LINC00628 suppresses the growth and metastasis and promotes cell apoptosis in breast cancer.

OBJECTIVE: Breast cancer is the most common malignant tumor in women. However, the detailed mechanisms of its tumorigenesis remain largely unknown. Evidence and data have shown that abnormality in expression of Long non-coding RNA (LncRNA) is closely related to tumorigenesis. The aim of this study is to identify the detailed mechanisms of LncRNA LINC00628 in breast cancer. PATIENTS AND METHODS: The expression of LINC00628 in breast cancer tissues, adjacent non-cancerous tissues and cell lines were detected by qRT-PCR. Kaplan-Meier method and log-rank test were applied to analyze the overall survival of patients with low and high expression level of LINC00628 respectively. The LCC2 and MCF-7 cells were transfected with LINC00628 and the proliferation, invasion and migration were examined. The cell cycle distribution and cell apoptosis rate in LCC2 and MCF-7 cells after transfection with LINC00628 were explored by flow cytometry. The relative expression level of Bcl-2, Bax and Caspase-3 protein in LCC2 and MCF-7 cells after transfection with LINC00628 was detected by Western blotting. RESULTS: The relative expression level of LINC00628 in breast cancer tissues and cell lines were significantly decreased and the low expression level of LINC00628 has a poorer prognosis and lower overall survival rate. The overexpression of LINC00628 suppressed breast cancer cells proliferation, invasion and migration. Further, with the overexpression of LINC00628, cell cycle was arrested in G0/G1 phase in breast cancer cells and cell apoptosis was promoted. The relative expression of Caspase-3 and Bax protein were significantly increased and the relative expression of Bcl-2 protein was significantly decreased after transfection with LINC00628. CONCLUSIONS: The expression of LINC00628 was decreased in breast cancer. The overexpression of LINC00628 suppressed the proliferation, invasion and migration of breast cancer cells and promoted cell apoptosis associated with the regulation of Bcl-2/Bax/Caspase-3 signal pathway.

[Hospital costs and related influencing factors in patients with acute poisoning].

Objective: To investigate the hospital costs and related influencing factors in patients with acute poisoning. Methods: A retrospective analysis was performed for the general status and hospital costs of 373 patients with acute poisoning who were admitted to The Second Affiliated Hospital of Wenzhou Medical College from January 2009 to March 2015. The questionnaires were completed, the data were entered into Excel forms, and SPSS 18.0 was used to perform statistical analysis. Results: Among the 373 patients, 44.8% committed suicide and 31.1% were poisoned by accidental contact; 42.6% were poisoned by pesticides, and 32.7% were poisoned by drugs. After treatment, 64.1% achieved improvements, whereas 1.3% died. The highest hospital cost reached 62 710.26 RMB, and the lowest was 64.64 RMB (median 4 328 RMB) . The patients with an older age and a longer length of hospital stay tended to have higher hospital costs; the patients who underwent catharsis, mechanical ventilation, and blood purification and were admitted to the intensive care unit had relatively high hospital costs. Conclusion: The patients with acute poisoning have high hospital costs. Poisoning caused by pesticides and drugs should be prevented and treated with priority, so as to reduce the heavy economic burden caused by acute poisoning.

[The surgical management of giant intracranial vestibular schwannoma via retrosigmoid approach: a retrospective review of 657 cases].

OBJECTIVE: To discuss the surgical technique and common complications from the microsurgical treatment of giant intracranial vestibular schwannoma via suboccipital retrosigmoid approach and to propose strategies for minimizing such complications. METHODS: Surgical outcomes and complications were evaluated in a consecutive series of 657 unilateral giant vestibular schwannomas treated in Shanghai Huashan Hospital via suboccipital retrosigmoid approach from 1999 to 2014. According to the international classification of vestibular schwannoma, giant tumor means tumor's size over 4 cm in diameter. Clinical status and complications were assessed postoperatively within 14 days and at follow-ups (range, 6-191 months; mean, 59.6 months). RESULTS: Follow-up data were available for 566 of the 657 patients (86.1%). The most frequent clinical symptoms were hearing loss in different levels (100%), deafness (36.4%), facial numbness (68.8%). Total tumor resection was achieved in 556 patients (84.6%), subtotal resection in 99 patients (15.1%), and partial resection in 2 patients (0.3%). The common postoperative complications included new deafness (49.6%), intracranial infection (7.6%), low cranial nerve defect (7.5%) and pneumonia (6.2%). The facial nerve was preserved anatomically in 589 cases (89.6%) after operation, and the functional valuation of facial nerve according to postoperative House-Brackmann showed 216 patients (32.9%) in grade Ⅰ-Ⅱ, 308 cases (46.9%) in grade Ⅲ, 133 patients (20.2%) in grade Ⅳ-Ⅵ. Long-term followed-up results showed 428 patients (75.6%) in grade Ⅰ-Ⅲ one year after surgical treatment. CONCLUSIONS: Many of these complications are avoidable. Surgical experiences and the clinical anatomy of the approach, accompany with using intraoperative nerve monitoring, preoperatively study the individual imaging and clinical data and multidisciplinary cooperation are the key points to avoid the complications of giant intracranial vestibular schwannoma via suboccipital retrosigmoid approach.

Resistin expression in adipose tissues and its effect on glucose metabolism in rats with brain injury.

Resistin (RSTN) expression in subcutaneous adipose tissue, and its effect on glucose metabolism in rats with traumatic brain injury, was investigated using real-time PCR, western blots, and enzyme linked immunoassays. Our results show that the expression of RSTN mRNA (3.192 ± 0.046, 4.016 ± 0.010, 6.004 ± 0.020, 8.213 ± 0.013, 11.199 ± 0.174, 15.094 ± 0.030), protein levels (1.79 ± 0.05, 1.98 ± 0.07, 2.75 ± 0.08, 3.19 ± 0.08, 4.25 ± 0.11, 4.48 ± 0.07), levels of serum insulin (512.96 ± 1.21, 580.57 ± 1.52, 769.71 ± 2.22, 826.08 ± 2.03, 1262.25 ± 3.40, 1512.80 ± 3.93), and fasting blood glucose levels (10.277 ± 0.040, 12.776 ± 0.038, 13.403 ± 0.263, 14.698 ± 0.100, 16.637 ± 0.110, 19.416 ± 0.025) were significantly higher in the traumatic rat group compared to the control group (P < 0. 05). Quantitative insulin sensitivity check index (QUICKI) was significantly lower in the traumatic group (-8.570 ± 0.005, -8.912 ± 0.004, -9.241 ± 0.022, -9.404 ± 0.007, -9.952 ± 0.007, -10.288 ± 0.002) than in the control group (-7.633 ± 0.003, -7.639 ± 0.004, -7.637 ± 0.006, -7.643 ± 0.003, -7.636 ± 0.006, -7.634 ± 0.004) (P < 0.05). Single factor linear correlation analysis showed that there was a significant negative correlation between RSTN expression and QUICKI (-0.983, P < 0.05) in the traumatic group. The increase in RSTN expression in the subcutaneous adipose tissue of rats with traumatic brain injury is likely related to the indexes of glycometabolism, including serum insulin, fasting blood glucose, and QUICKI. Our results lead us to conclude that RSTN may play an important role in the process of insulin resistance in rats with traumatic brain injury.

H558R polymorphism in SCN5A is associated with Keshan disease and QRS prolongation in Keshan disease patients.

Keshan disease (KSD), a potentially fatal cardiomyopathy, has very high incidence in some selenium-poor regions of China. KSD may be accompanied with a variety of arrhythmia, which is associated with mutations in the gene coding for cardiac voltage-gated sodium channel (SCN5A). The molecular mechanism of KSD is still largely obscure. We aimed to determine the association between the H558R polymorphism of SCN5A and KSD. We recruited 71 patients with KSD and 80 geographical region-matched control subjects in our study. Vital sign and electrocardiographic (ECG) measurements were performed for heart rate, systolic pressure, diastolic pressure, PR interval, QT interval, QRS duration, ST-T changes and complete right bundle branch block (CRBBB), and H558R polymorphism was genotyped using the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) method and sequencing. A significant association was found between the H558R polymorphism of exon 12 and KSD. Allele C carriers had a decreased risk for KSD with an odds ratio of 0.332 [95% confidence interval (CI), 0.160-0.692] as well as for QRS prolongation in KSD patients with an odds ratio of 0.089 (95%CI, 0.022-0.361). Our results provide support to the association between H558R polymorphism and the decreased risk for KSD. H558R polymorphism might increase susceptibility to KSD, and SCN5A containing the polymorphism might be a predisposing gene for QRS prolongation.

B-mode ultrasonographic evaluation of the testis in relation to serum testosterone concentration in male Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) during the breeding season.

The use of ultrasonography as a noninvasive tool for assessing the reproductive status of the male Yangtze finless porpoise (YFP; Neophocaena phocaenoides asiaeorientalis) was validated by correlating ultrasonographically determined testicular volume (TV) and testicular parenchyma pixel intensity (PI) with serum testosterone (T) concentration. The testes of 13 free-ranging male YFPs from the Tian-e-Zhou Reserve and three captive animals from the Baiji Dolphinarium (Wuhan, China) were examined ultrasonographically during April 2008. Testis volume was determined using Lambert's formula for an ellipsoid. Testicular parenchyma PI was evaluated by analyzing testicular ultrasonograms using pixel analysis software (Image J). Serum T concentrations were determined using a single-antibody radioimmunoassay. The TV, PI, and serum T concentration were low and similar in animals with body length <133 cm, highest in those with body length >or=142 cm, and highly variable in those with body length from 133 to 141 cm. Both TV and PI were closely correlated with serum T concentration (r=0.91 and r=0.85, respectively; P<0.01), indicating a consistent association between structural and functional development of the testis. In conclusion, we inferred that puberty onset in male YFPs occurred when TV was >150 cm(3) and PI was >60 during the breeding season and that testicular ultrasonography and pixel analysis was an efficient, noninvasive, real-time tool to evaluate testicular function of live male YFPs.

Ultrastructure of the spermatozoa of the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis).

Semen sample was collected from two captive adult Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) during physical examination. One individual was aged about 9 years with body length 143 cm (total length) and body weight 46.1 kg in 2003. The age of the other was unknown and its body length was 147 cm and body weight was 43 kg in 2004. Ultrastructure of their spermatozoa was examined using scanning and transmission electron microscope. The sperm concentration was 4.17 x 10(9) spermatozoa per ml by the cytometer. The approximate dimensions of the spermatozoa were as follows: head length, 3.366 +/- 0.140 microm (mean +/- SE, n = 15); head width, 1.896 +/- 0.099 microm (n = 15); and neck length, 1.004 +/- 0.074 microm (n = 10). The tail included midpiece, principal piece and terminal piece. The length of the midpiece was 1.882 +/- 0.077 microm (n = 9). There is no apparent boundary between the principal piece and the terminal piece, so the length of the principal piece and the terminal piece was 44.612 +/- 3.485 microm (n = 5). Total length of the spermatozoa was 53.314 +/- 4.580 microm (n = 10). The acrosome covered approximately 45.8% of the anterior portion of the head.

A non-synonymous single nucleotide polymorphism in IFNAR1 affects susceptibility to chronic hepatitis B virus infection.

The type I interferon (IFN-alpha/beta) receptor 1 (IFNAR1) mediates the potent antiviral and immuno-regulatory effects of IFN-alpha/beta that are believed to be pivotal to eradicate hepatitis B virus (HBV) infection. IFNAR1 promoter polymorphisms (at -568/-77) have been shown to be associated with susceptibility to chronic HBV infection; however, whether these markers are genetic determinants of HBV infection remains unknown. The functional significance of promoter -568/-77 polymorphisms was assessed by mutagenesis and luciferase assays. Sequencing and restriction fragment length polymorphisms in 328 chronic HBV patients, 130 spontaneous resolvers and 148 healthy blood donors identified other polymorphism at IFNAR1 open reading frame. IFNAR1 expression levels in peripheral blood cells were detected by flow cytometry. We found that the -568/-77 promoter variants were unlikely to affect transcription levels. A C/G single nucleotide polymorphism, in strong linkage disequilibrium with the promoter polymorphisms, was found in the coding sequence of IFNAR1 (nt19158). This resulted in a nonsynonymous substitution in the extracellular region of IFNAR1 protein and correlated with susceptibility to chronic HBV infection. Bioinformatic analysis suggested decreased stability of the IFNAR1 protein. Chronic HBV patients with the 19158C/C genotype (Leu141) exhibited higher IFNAR1 protein expression levels in peripheral blood monocytes than those with the 19158G/G genotype (Val141). In conclusion, IFNAR1 19158C/G polymorphism is primarily associated with susceptibility to chronic HBV infection.

A survey of Chinese herbal medicine intake amongst preoperative patients in Hong Kong.

We have surveyed, by means of a questionnaire, the preoperative use of traditional Chinese medicines in 259 adult Chinese patients admitted to a Hong Kong teaching hospital. The spectrum and use of herbal remedies differed from that reported by Western sources. Of those patients surveyed 90% used Chinese herbs on a regular daily basis in traditional soups and teas while 44% had consulted a traditional Chinese medicine practitioner in the last twelve months prior to admission, but mainly for health promotion (59%) and minor ailments (30%). Only 25% sought advice for their current illness and 13% were taking regular traditional Chinese medicines prior to admission. The ingredients were difficult to identify. Patients with cancer were more likely to use ling zhi (odds ratio 5.4). Female patients with reproductive problems were more likely to visit a traditional Chinese medical practitioner (odds ratio 2.6) and use ginseng (odds ratio 5.1). The anaesthetic implications of preoperative traditional Chinese medicine in keeping with Hong Kong practices need to be investigated, and appropriate anaesthetic guidelines should be developed.

Pre-operative hepatitis in a woman treated with Chinese medicines.

A 37-year-old Hong Kong Chinese female with cervical cancer was scheduled for radical hysterectomy and lymphadenectomy. Her past health was good. Pre-operatively, she was found to have a fatty liver, prolonged prothrombin time and abnormal liver function tests. Surgery was not postponed and she was anaesthetised uneventfully, using a general anaesthetic technique. The procedure lasted 4 h. Postoperatively, she developed a large pelvic haematoma and a wound infection. Her coagulation and liver function tests gradually returned to normal. No obvious medical cause for her liver dysfunction could be found. However, it emerged that she had received a 6-week course of traditional Chinese medicines prior to admission. The prescriptions contained over 60 different ingredients, some of which were known to be hepatotoxic, cytotoxic or to cause bleeding. This was the most likely explanation for her liver dysfunction.

Episomal expression of specific sense and antisense mRNAs in Leishmania amazonensis: modulation of gp63 level in promastigotes and their infection of macrophages in vitro.

The major surface glycoprotein (gp63) of Leishmania amazonensis is a metalloprotease implicated in the infection of mammalian macrophages. The expression of gp63 and its participation in this infection were further examined by modulating the level of this molecule in a virulent gp63-abundant wild-type clone. Promastigotes were transfected with gp63 genes cloned into a Leishmania-specific vector in two different orientations, leading to the expression of gp63 sense and antisense RNAs. With increasing selective pressure, cell surface gp63 was increasingly augmented in the transfectants with sense transcripts and suppressed to a very low level in those with antisense transcripts. Thus, the expression of gp63 from chromosomal, repetitive genes is not stringently regulated at the protein level and can be substantially reduced by episomal antisense transcription of a single copy. The transfectants differed significantly only in the level of gp63, thereby allowing specific evaluation of this molecule in leishmanial infection of macrophages in vitro. Kinetic studies of infection in vitro indicate that gp63 plays a role not only in the binding of this parasite to these macrophages but also in its intramacrophage survival and replication.