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Biomedical subjects

W Zhang

Publications and source records attributed to W Zhang.

At least 19 recordsLinked to original sources

Polymorphisms of short tandem repeat of genes and breast cancer susceptibility.

AIM: To explore the relationship of short tandem repeat polymorphisms and breast cancer susceptibility. METHODS: We searched the MEDLINE database (up to June 2006) with the keywords of tandem repeat sequences, gene polymorphisms, breast cancer, cancer susceptibility and microsatellite instability. We reviewed the literature on gene polymorphisms, especially the relationship of short tandem repeat and breast cancer risk. RESULTS: We focused on the candidate genes sex hormones, steroid hormone and receptors, carcinogen metabolism, cell proliferation regulation and other genes. CONCLUSIONS: The functional effects of short tandem repeat polymorphisms on cancer susceptibility, especially on breast cancer risk, are identified. The importance of short tandem repeat polymorphisms on development and progression of breast cancer are discussed.

Breast Neoplasms↗

Is the dementia rate increasing in Beijing? Prevalence and incidence of dementia 10 years later in an urban elderly population.

OBJECTIVE: To examine the time trend of dementia morbidity over the past decade in Beijing, China. METHOD: In 1997, 1593 community-dwelling elderly aged 60+ years were examined and followed-up over 2-years to identify incident dementia. A similar cohort study of dementia conducted in the same district 10 years prior was used as historical comparison to examine the time trend of dementia incidence. RESULTS: Forty prevalent dementia cases were identified at the initial examination for a prevalence of 2.51% (95% CI: 1.74-3.28) and 25 incident cases were identified at the follow-up visit for an incidence of 0.90% (0.55-1.25) among residents aged 60+ years. Alzheimer's dementia (AD) was the most common type of dementia in both prevalent and incident cases. CONCLUSION: The prevalence and incidence rates of dementia in Beijing were slightly higher than those 10 years ago, which was partly because of population aging. AD became the most common subtype of dementia.

Aged↗

Site-directed alkylation and the alternating access model for LacY.

In a functional lactose permease mutant from Escherichia coli (LacY) devoid of native Cys residues, almost every residue was replaced individually with Cys and tested for reactivity with the permeant alkylating agent N-ethylmaleimide in right-side-out membrane vesicles. Here we present the results in the context of the crystal structure of LacY. Engineered Cys replacements located near or within the inward-facing hydrophilic cavity or at other solvent-accessible positions in LacY react well with this alkylating agent. Cys residues facing the low dielectric of the membrane or located in tightly packed regions of the structure react poorly. Remarkably, in the presence of ligand, increased reactivity is observed with Cys replacements located predominantly on the periplasmic side of the sugar-binding site. In contrast, other Cys replacements largely on the cytoplasmic side of the binding site exhibit decreased reactivity. Furthermore, both sets of Cys replacements in the putative cavities are located at the periplasmic (increased reactivity) and cytoplasmic (decreased reactivity) ends of the same helices and distributed in a pseudosymmetrical manner. The results are consistent with a model in which the single sugar-binding site in the approximate middle of the molecule is alternately exposed to either side of the membrane due to opening and closing of cytoplasmic and periplasmic hydrophilic cavities.

Alkylating Agents↗

EULAR evidence based recommendations for the management of hand osteoarthritis: report of a Task Force of the EULAR Standing Committee for International Clinical Studies Including Therapeutics (ESCISIT).

OBJECTIVES: To develop evidence based recommendations for the management of hand osteoarthritis (OA). METHODS: The multidisciplinary guideline development group comprised 16 rheumatologists, one physiatrist, one orthopaedic surgeon, two allied health professionals, and one evidence based medicine expert, representing 15 different European countries. Each participant contributed up to 10 propositions describing key clinical points for management of hand OA. Final recommendations were agreed using a Delphi consensus approach. A systematic search of Medline, Embase, CINAHL, Science Citation Index, AMED, Cochrane Library, HTA, and NICE reports was used to identify the best available research evidence to support each proposition. Where possible, the effect size and number needed to treat were calculated for efficacy. Relative risk or odds ratio was estimated for safety, and incremental cost effectiveness ratio was used for cost effectiveness. The strength of recommendation was provided according to research evidence, clinical expertise, and perceived patient preference. RESULTS: Eleven key propositions involving 17 treatment modalities were generated through three Delphi rounds. Treatment topics included general considerations (for example, clinical features, risk factors, comorbidities), non-pharmacological (for example, education plus exercise, local heat, and splint), pharmacological (for example, paracetamol, NSAIDs, NSAIDs plus gastroprotective agents, COX-2 inhibitors, systemic slow acting disease modifying drugs, intra-articular corticosteroids), and surgery. Of 17 treatment modalities, only six were supported by research evidence (education plus exercise, NSAIDs, COX-2 inhibitors, topical NSAIDs, topical capsaicin, and chondroitin sulphate). Others were supported either by evidence extrapolated from studies of OA affecting other joint sites or by expert opinion. Strength of recommendation varied according to level of evidence, benefits and harms/costs of the treatment, and clinical expertise. CONCLUSION: Eleven key recommendations for treatment of hand OA were developed using a combination of research based evidence and expert consensus. The evidence was evaluated and the strength of recommendation was provided.

Anti-Inflammatory Agents, Non-Steroidal↗

Degeneration of the Golgi and neuronal loss in dorsal root ganglia in diabetic BioBreeding/Worcester rats.

AIMS/HYPOTHESIS: The aim of this study was to evaluate the nature and extent of neuronal loss in dorsal root ganglia (DRG) in diabetic polyneuropathy. MATERIALS AND METHODS: We examined 10-month diabetic BioBreeding/Worcester (BB/Wor) rats with respect to DRG ultrastructure and morphometry, sural nerve morphometry, pro- and anti-apoptotic proteins, the expression of neurotrophic factors and their receptors, and sensory nerve functions. RESULTS: In diabetic rats, DRG neurons decreased to 73% of normal, owing to loss of substance P and calcitonin gene-related peptide-positive neurons. Levels of pro-apoptotic active caspase-3, Bax and low-affinity nerve growth factor (NGF) were increased in DRG. The concentration of anti-apoptotic heat shock protein (HSP) 70 in DRG was decreased, whereas concentrations of Bcl-xl and HSP27 were unaltered. Levels of poly(ADP-ribose) polymerase (PARP) and cleaved PARP were unaltered. Levels of NGF in sciatic nerve and concentrations of the high-affinity NGF receptor, insulin receptor and IGF-I receptor in DRG were significantly decreased. Sensory nerve conduction velocity decreased to 78% of normal. Hyperalgesia increased up to 6 months. Myelinated and unmyelinated fibre numbers of the sural nerve were significantly decreased in diabetic rats. DRG examinations revealed no evidence of apoptosis, mitochondrial changes or abnormalities of the endoplasmic reticulum. Instead, neurons demonstrated progressive vacuolar degenerative changes of the Golgi apparatus, with fragmentation and formation of large cytoplasmic vacuoles. These data show that sustained apoptotic stress is present in DRG of chronically diabetic BB/Wor rats, but fails to proceed to apoptotic cell death. CONCLUSIONS/INTERPRETATION: Progressive DRG neuronal loss, particularly of small neurons, occurs in the type 1 diabetic BB/Wor rat. This is associated with neurotrophic withdrawal and progressive degeneration of the Golgi apparatus.

Animals↗

Sensitive and selective liquid chromatography-mass spectrometry method for the quantification of rosiglitazone in human plasma.

A sensitive and selective high-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (HPLC-ESI-MS-MS) method for determination of rosiglitazone in human plasma has been developed. After the addition of the internal standard, plasma samples were precipitated by acetonitrile. The compounds were separated on a proC18 column using a mixture of ammonium acetate buffer (0.02 M, pH 6.5) and acetonitrile (in the ratio of 47:53, v/v) as mobile phase. A Finnigan LCQdeca plus ion trap mass spectrometer connected to a Finnigan Surveyor HPLC was used to develop and validate the method. Linearity was established for the range of concentrations 1-1000 ng/ml with a coefficient of determination (r(2)) of 0.999. The intra-day accuracy for rosiglitazone ranged from 110.0 to 99.2% at low, medium and high levels. The inter-day accuracy was less than 15%. The lower limit of quantitation (LLOQ) was identified reproducible at 1.0 ng/ml with a precision of 5.7%. After validation, the method was used to study the pharmacokinetic profile of rosiglitazone in five healthy volunteers after administration of a single oral dose (4.0mg). The proposed method enabled the unambiguous evaluation and quantitation of rosiglitazone for pharmacokinetic, bioavailability or drug-drug interaction studies. A possible chromatography peak (m/z 121, its parent ion m/z 344) of N-demethyl rosiglitazone was observed at 3.49 min during determining rosiglitazone. This may be also a potential method for simultaneous determination of rosiglitazone and its metabolite N-demethyl rosiglitazone concentrations in plasma.

Administration, Oral↗

Earthworm cytochrome P450 determination and application as a biomarker for diagnosing PAH exposure.

We developed a new microsome purification method and used the Omura and Sato method to measure the total content of cytochrome (Cyt) P450 in earthworm (Eisenia fetida) microsomes. In method development, two different pretreatments, i.e. solubilization or manual separation were used to purify worm microsomes. Solubilization was more effective than manual separation and difference spectra showed a peak at 450 +/- 1 nm in microsomes received solubilization pretreatment. We conducted a 48 h contact test by exposing worms on pyrene (Py) and benzo[a]pyrene (BaP) spiked filter paper. A dose-response relationship was established between total P450 content and the concentration of Py or BaP ranging from 10(-6) mg mL(-1) to 10(-2) mg mL(-1). Results show that total Cyt P450 content in earthworms is a promising biomarker for diagnosing PAHs exposure at sublethal dose ranges.

Animals↗

Mycobacterium avium subspecies paratuberculosis infection of cattle does not diminish peripheral blood-derived macrophage mycobactericidal activity.

Ruminants infected with Mycobacterium avium subspecies paratuberculosis consistently develop a multibacillary form of disease that is centered on the ileum. Mechanisms responsible for failure of macrophage function during multibacillary disease are incompletely characterized. Our data suggest that mycobactericidal functions are present, and potentially enhanced, in monocyte-derived macrophages from M. avium subsp. paratuberculosis infected cattle. Addition of CD4(+) T cells from infected animals to autologous in vitro infected macrophages did not increase bacterial killing. In contrast, CD4(+) T cells from non-infected animals did increase bacterial killing in autologous macrophages. In macrophages from both infected and non-infected cattle, bacterial killing appeared to be independent of interferon-gamma (IFN-gamma) and nitric oxide production.

Animals↗

Systemic inhibition of tumor growth by soluble Flk-1 gene therapy combined with cisplatin.

Soluble Flk-1, a soluble vascular endothelial growth factor (VEGF) receptor, is a potent inhibitor of angiogenesis, which could restrain growth and metastasis of some experimental tumors. However, antiangiogenic agents alone cannot eradicate tumor completely, and should be combined with other therapy to enhance their effects. In this study, we evaluated the antitumor activity of the combination therapy in the immunocompetent BALB/c mice bearing H22 hepatoma and Meth A fibrosarcoma, respectively. Mice were treated with either msFlk-1 i.m. at 100 microg/mouse once every 3 days for four times from day 3 after the tumor cell injection, cisplatin cycled twice (2 mg/kg i.p. on days 4 and 11 after the tumor cell inoculation), or both agents together. Tumor growth and survival time were continually observed. Antiangiogenesis in vivo was determined by CD31 immunohistochemistry. Assessment of apoptotic cells and histological analysis was also conducted in tumor tissues. Our results showed that the combination therapy could evidently improve antitumor efficacy, including tumor growth suppression, mice survival prolongation, tumor cell apoptosis augmentation as well as neovascularization inhibition as compared with controls, without serious adverse effects. Our data suggest that the combination of DDP with msFlk-1 is more effective to suppress tumor growth in mice than either agent alone, and this combination regimen showed its potential for future clinical application.

Animals↗

The antitumor activity of TRAIL and IL-24 with replicating oncolytic adenovirus in colorectal cancer.

Melanoma differentiation associated gene-7 (Mda-7)/IL-24 was previously cloned into ZD55 (an adenovirus with E1B55 deleted) to form ZD55-IL-24, which had much better antitumor effect than Ad-IL-24. According to its good antitumor properties, ZD55-IL-24 has been used in preclinical studies. But ZD55-IL-24 alone still could not completely eradicate established tumors in all nude mice. It was reported that IL-24 could induce and enhance the activity of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) (a member of tumor necrosis factor (TNF) superfamily). Accordingly, the combined use of ZD55-IL-24 and ZD55-TRAIL was carried out in this study. Treatment with both ZD55-IL-24 and ZD55-TRAIL could induce more significant apoptosis in cancer cells in vitro compared with ZD55-IL-24 or ZD55-TRAIL alone. The combination of the two replicative adenoviruses had better antitumor activity in vivo than that of single oncolytic adenovirus and led to complete eradication of xenograft tumors in all treated mice. Upregulation of TRAIL was observed in tumor cells infected with ZD55-IL-24 and studies of the apoptotic cascade regulators indicate that ZD55-IL-24 could further enhance the activation of apoptosis through the TNF family of death receptors. We demonstrated for the first time the potential therapeutic effect of combined ZD55-IL-24 with ZD55-TRAIL for the targeted therapy of cancer.

Adenoviridae↗

The preventive and therapeutic effects of GCPII (NAALADase) inhibition on painful and sensory diabetic neuropathy.

Excitotoxic glutamate release occurs in several neurological disorders. One source is derived from the hydrolysis of the neuropeptide N-acetyl aspartyl glutamate (NAAG) by glutamate carboxypeptidase II (GCPII, also known as NAALADase). Drugs that attenuate glutamate transmission have been shown to relieve neuropathic pain, however side effects have limited their clinical use. It appears that GCPII is exclusively recruited to provide a glutamate source in hyperglutamatergic, excitotoxic conditions and therefore would be devoid of such side effects. Here we report on the therapeutic effects of an orally bio-available GCP II inhibitor on established painful and sensory neuropathy in the spontaneously diabetic BB/Wor rat. It significantly improved hyperalgesia, nerve conduction velocity and underlying myelinated fiber atrophy. The data suggest that GCP II inhibition may provide a meaningful and effective approach to the treatment of painful diabetic neuropathy.

Analysis of Variance↗

Air quality improvement estimation and assessment using contingent valuation method, a case study in Beijing.

The aim of the paper is to estimate and assess residents' willingness to pay to improve air quality in the urban area of Beijing using the Contingent Valuation Method (CVM). The mean willingness to pay (WTP) for a 50% reduction of harmful substances in the air was 143 CNY per household per year, and the total WTP of the residents in the study area was 336 million CNY per year. As a proportion of household annual income, the mean WTP amounted to 0.7%. Four socio-economic variables were found to have significant impacts on residents' willingness to pay. The analysis results illustrated that WTP increases with income and education level, and decreases with household population and age. The willingness was larger for residents in the urban districts than those in the suburban districts. It was found that most of the protest bids lay on interviewees' incomplete perception of the values of environmental amenity. The influence of household income on people's willingness to pay illustrated in this study reflects a causal force of Beijing's transition to market economy that households created to have disposable income are more likely to care about environmental quality. The results of this study strike an optimistic note on the possibility of measuring the total economic value of environmental quality improvement by using the CVM in China. Suggestions on implication of the CVM for both academics and policy makers are provided in the paper.

Air↗

EULAR evidence based recommendations for gout. Part I: Diagnosis. Report of a task force of the Standing Committee for International Clinical Studies Including Therapeutics (ESCISIT).

OBJECTIVE: To develop evidence based recommendations for the diagnosis of gout. METHODS: The multidisciplinary guideline development group comprised 19 rheumatologists and one evidence based medicine expert, representing 13 European countries. Ten key propositions regarding diagnosis were generated using a Delphi consensus approach. Research evidence was searched systematically for each proposition. Wherever possible the sensitivity, specificity, likelihood ratio (LR), and incremental cost-effectiveness ratio were calculated for diagnostic tests. Relative risk and odds ratios were estimated for risk factors and co-morbidities associated with gout. The quality of evidence was categorised according to the evidence hierarchy. The strength of recommendation (SOR) was assessed using the EULAR visual analogue and ordinal scales. RESULTS: 10 key propositions were generated though three Delphi rounds including diagnostic topics in clinical manifestations, urate crystal identification, biochemical tests, radiographs, and risk factors/co-morbidities. Urate crystal identification varies according to symptoms and observer skill but is very likely to be positive in symptomatic gout (LR = 567 (95% confidence interval (CI), 35.5 to 9053)). Classic podagra and presence of tophi have the highest clinical diagnostic value for gout (LR = 30.64 (95% CI, 20.51 to 45.77), and LR = 39.95 (21.06 to 75.79), respectively). Hyperuricaemia is a major risk factor for gout and may be a useful diagnostic marker when defined by the normal range of the local population (LR = 9.74 (7.45 to 12.72)), although some gouty patients may have normal serum uric acid concentrations at the time of investigation. Radiographs have little role in diagnosis, though in late or severe gout radiographic changes of asymmetrical swelling (LR = 4.13 (2.97 to 5.74)) and subcortical cysts without erosion (LR = 6.39 (3.00 to 13.57)) may be useful to differentiate chronic gout from other joint conditions. In addition, risk factors (sex, diuretics, purine-rich foods, alcohol, lead) and co-morbidities (cardiovascular diseases, hypertension, diabetes, obesity, and chronic renal failure) are associated with gout. SOR for each proposition varied according to both the research evidence and expert opinion. CONCLUSIONS: 10 key recommendations for diagnosis of gout were developed using a combination of research based evidence and expert consensus. The evidence for diagnostic tests, risk factors, and co-morbidities was evaluated and the strength of recommendation was provided.

Advisory Committees↗

EULAR evidence based recommendations for gout. Part II: Management. Report of a task force of the EULAR Standing Committee for International Clinical Studies Including Therapeutics (ESCISIT).

OBJECTIVE: To develop evidence based recommendations for the management of gout. METHODS: The multidisciplinary guideline development group comprised 19 rheumatologists and one evidence based medicine expert representing 13 European countries. Key propositions on management were generated using a Delphi consensus approach. Research evidence was searched systematically for each proposition. Where possible, effect size (ES), number needed to treat, relative risk, odds ratio, and incremental cost-effectiveness ratio were calculated. The quality of evidence was categorised according to the level of evidence. The strength of recommendation (SOR) was assessed using the EULAR visual analogue and ordinal scales. RESULTS: 12 key propositions were generated after three Delphi rounds. Propositions included both non-pharmacological and pharmacological treatments and addressed symptomatic control of acute gout, urate lowering therapy (ULT), and prophylaxis of acute attacks. The importance of patient education, modification of adverse lifestyle (weight loss if obese; reduced alcohol consumption; low animal purine diet) and treatment of associated comorbidity and risk factors were emphasised. Recommended drugs for acute attacks were oral non-steroidal anti-inflammatory drugs (NSAIDs), oral colchicine (ES = 0.87 (95% confidence interval, 0.25 to 1.50)), or joint aspiration and injection of corticosteroid. ULT is indicated in patients with recurrent acute attacks, arthropathy, tophi, or radiographic changes of gout. Allopurinol was confirmed as effective long term ULT (ES = 1.39 (0.78 to 2.01)). If allopurinol toxicity occurs, options include other xanthine oxidase inhibitors, allopurinol desensitisation, or a uricosuric. The uricosuric benzbromarone is more effective than allopurinol (ES = 1.50 (0.76 to 2.24)) and can be used in patients with mild to moderate renal insufficiency but may be hepatotoxic. When gout is associated with the use of diuretics, the diuretic should be stopped if possible. For prophylaxis against acute attacks, either colchicine 0.5-1 mg daily or an NSAID (with gastroprotection if indicated) are recommended. CONCLUSIONS: 12 key recommendations for management of gout were developed, using a combination of research based evidence and expert consensus. The evidence was evaluated and the SOR provided for each proposition.

Acute Disease↗

Effect of cilnidipine on left ventricular function in hypertensive patients as assessed by tissue Doppler Tei index.

Tissue Doppler Tei index is pointed to be more effective in the evaluation of global cardiac function than systolic and diastolic measurements alone in various heart diseases. This study was designed to assess the effect of cilnidipine on left ventricular function in hypertensive patients by using this index. A group of 40 hypertensives (mean age 55+/-8 years, range: 35-65) and 16 controls (mean age 52+/-9 years, range: 36-65) were included. Hypertensives were classified into non-left ventricular hypertrophy (NLVH) group (25 patients) and left ventricular hypertrophy (LVH) group (15 patients), and treated with cilnidipine for 2 months. Before and after treatment, the participants were examined by echocardiography. Tissue Doppler Tei index was calculated as diastolic time interval measured from end of late diastole to origin of early diastole (a') minus systolic Sm duration (b') divided by b', that is Tei index = (a'-b')/b'. Thirty-seven hypertensive patients finished the treatment. Tei index was significantly higher in NLVH and LVH groups than in control group, and in LVH group than in NLVH group (0.44+/-0.07 vs 0.28+/-0.06, P < 0.001; 0.51+/-0.13 vs 0.28+/-0.06, P < 0.001; 0.51+/-0.13 vs 0.44+/-0.07, P < 0.05). After treatment, Tei index was significantly decreased (0.40+/-0.11 vs 0.46+/-0.10, P < 0.0001); systolic blood pressure and diastolic blood pressure were also decreased significantly. In conclusion, Tei index is impaired in hypertensives before development of ventricular hypertrophy and impairment is more prominent in hypertrophy. Cilnidipine can improve left ventricular function. Tissue Doppler Tei index is gaining importance in evaluating LV function after drug intervention in hypertensive patients.

Calcium Channel Blockers↗

alpha-Neurexins are required for efficient transmitter release and synaptic homeostasis at the mouse neuromuscular junction.

Neurotransmission at chemical synapses of the brain involves alpha-neurexins, neuron-specific cell-surface molecules that are encoded by three genes in mammals. Deletion of alpha-neurexins in mice previously demonstrated an essential function, leading to early postnatal death of many double-knockout mice and all triple mutants. Neurotransmitter release at central synapses of newborn knockouts was severely reduced, a function of alpha-neurexins that requires their extracellular sequences. Here, we investigated the role of alpha-neurexins at neuromuscular junctions, presynaptic terminals that lack a neuronal postsynaptic partner, addressing an important question because the function of neurexins was hypothesized to involve cell-adhesion complexes between neurons. Using systems physiology, morphological analyses and electrophysiological recordings, we show that quantal content, i.e. the number of acetylcholine quanta released per nerve impulse from motor nerve terminals, and frequency of spontaneous miniature endplate potentials at the slow-twitch soleus muscle are reduced in adult alpha-neurexin double-knockouts, consistent with earlier data on central synapses. However, the same parameters at diaphragm muscle neuromuscular junctions showed no difference in basal neurotransmission. To reconcile these observations, we tested the capability of control and alpha-neurexin-deficient diaphragm neuromuscular junctions to compensate for an experimental reduction of postsynaptic acetylcholine receptors by a compensatory increase of presynaptic release: Knockout neuromuscular junctions produced significantly less upregulation of quantal content than synapses from control mice. Our data suggest that alpha-neurexins are required for efficient neurotransmitter release at neuromuscular junctions, and that they may perform a role in the molecular mechanism of synaptic homeostasis at these peripheral synapses.

Animals↗

Expression of drug pathway proteins is independent of tumour type.

Current clinicopathological staging systems have the advantage of standardized criteria for assessing tumour stage, and a relationship between advancing tumour stage and poor prognosis has been established for most cancers. However, these tools have not led to clear criteria for therapy selection in individual patients. Indeed, the concept of therapy based on anatomical location seems quaint. Therefore, a representative drug pathway (irinotecan) was evaluated across common tumour types to test the hypothesis that pharmacological proteins are expressed independent of anatomical location. Many enzymes are involved in controlling the disposition of irinotecan, including the cellular target (TOP1), metabolism enzymes (CES2, UGT1A1, CYP3A4, CYP3A5), and cellular transporters of the anti-cancer agent (ABCB1, ABCC1, ABCC2, ABCC3, ABCC5, ABCG2). These 11 proteins were evaluated in tissue microarrays containing colon, breast, prostate, ovary, and lung cancers; brain tumours; melanoma; lymphoma; and selected normal tissues. A total of 255 tumours and 37 normal tissue samples were evaluable for all proteins. Linear discriminant analysis designed to predict the tissue type from the protein expression levels revealed a 49.6% misclassification rate, indicating that protein expression of this drug pathway is not associated with tissue type. Cluster analysis identified a variety of tumours with the same pharmacological profile. The anatomy independence of drug pathways stimulates efforts to move away from our traditional approaches to the selection of cancer therapy.

Adenocarcinoma↗

Molecular characterization and expression of the antimicrobial peptide defensin from the housefly (Musca domestica).

A 430-bp cDNA encoding the insect antimicrobial peptide defensin was cloned from the housefly, and designated Musca domestica defensin (Mdde). The open reading frame of the cDNA encoded a 92-amino acid peptide with an N-terminal signal sequence followed by a propeptide that is processed by cleavage to a 40-amino acid mature peptide. Northern analysis and in situ hybridization identified the corresponding mRNA in the fat body of bacterially challenged houseflies and in the epidermis of the body wall of naive and challenged houseflies. The Gram-negative bacterium (Escherichia coli) is a strong inducer of the gene. By RT-PCR, Mdde mRNA was also detected in naive and challenged insects. These findings suggest that the defensin gene is constitutively expressed in the epidermis of the housefly body wall. The predicted mature form of Mdde was expressed as a recombinant peptide in E. coli and Pichia pastoris. The recombinant Mdde expressed in Pichia was active against Gram-positive and some Gram-negative bacteria.

Amino Acid Sequence↗