Biomedical subjects

Y Lin

Publications and source records attributed to Y Lin.

At least 109 records · Page 6Linked to original sources

PubMed2001

[The role of neutrophils and interleukin-8 in pathogenesis of asthma].

OBJECTIVE: To investigate the role of neutrophils and interleukin-8 (IL-8) in pathogenesis of asthma. METHODS: Pulmonary function and bronchial provocation test were performed to identify and evaluate asthma. Superoxide anion O(2)(-.) generation of peripheral blood neutrophils, IL-8 and malondialhyde (MDA) levels in plasma and induced sputum were measured. RESULTS: The O(2)(-.) generation [(20.9 +/- 5.1) nmol] of peripheral blood neutrophils from moderate-severe asthmatics were significantly higher than that [(15.2 +/- 4.2) nmol] from mild asthmatics (P < 0.01), in which that was still significantly higher than that [(11.3 +/- 2.4) nmol] from normal subjects (P < 0.05). The O(2)(-.) generation of peripheral blood neutrophils had significantly negative correlation with PD(20)FEV(1) (r = -0.693, P < 0.05). The levels of IL-8 [(585 +/- 75) ng/L, (791 +/- 103) ng/L] and MDA levels [(6.3 +/- 1.6) mmol/L, (21.8 +/- 6.3) mmol/L] in plasma and induced sputum from unstable asthmatics were higher than those [(227 +/- 54) ng/L, (322 +/- 95) ng/L and (5.4 +/- 1.0) mmol/L, (15.1 +/- 5.6) mmol/L] from stable asthmatics (P < 0.01), more over, in the latter group, they were still significantly higher than those (188 +/- 46) ng/L, (224 +/- 51) ng/L and [(4.1 +/- 0.4) mmol/L, (9.5 +/- 4.2) mmol/L] from normal subjects (P < 0.05). The levels of MDA in the induced sputum from stable asthmatics showed a negative correlation with PD(20)FEV(1) (r = -0.708, P < 0.01). The levels of IL-8 in the induced sputum showed a positive correlation with percentage of neutrophils in the induced sputum (r = 0.838, P < 0.01). CONCLUSIONS: IL-8 and oxygen free radicals generated by neutrophils might participate in development of airway inflammation and airway hyperresponsiveness in asthma.

Adult↗

PubMed2001

[Clinical and radiographic evaluation of 108 dental implants after 1-year loading].

OBJECTIVE: To evaluate the clinical outcomes and a possible correlation between peri-implant mucosal inflammation and marginal bone loss in a group of Chinese patients who received IMZ and Frialit-2 implants one year after restoration. METHODS: The clinical and radiography parameters of 108 IMZ and Frialit-2 dental implants in 70 patients were measured. RESULTS: There were no signs of mobility and peri-implant radiolucencies in any of the implants. The average bone loss adjacent to implants was (0.63 +/- 0.78) mm. The prevalence of peri-implant mucosal inflammation, as indicated by suclus bleeding index (SBI) of 1.0 or more, was 32.9%. Significant correlation was found between mucosal inflammation and bone loss. The severely inflamed sites experienced greater bone loss than that of healthy or slightly inflamed sites (P < 0.05). In 92% of sites, plaque index (PLI) of more than 1 was measured on implant surfaces. The periodontal status of the remaining natural teeth in each subject was evaluated using the community periodontal index of treatment need (CPITN). Of the 70 examined patients, 15 patients needed oral hygiene instruction, 44 needed scaling and root planing, 8 patients needed periodontal surgical therapy, and only 3 did not need any periodontal treatment. CONCLUSIONS: The 1-year outcomes from this patient series indicated that IMZ and Frialit-2 implant provide satisfactory clinical results. One of the etiologic factors of alveolar bone loss around implants seems to be plaque-associated marginal inflammation. Improvement of oral hygiene, elimination of marginal tissue inflammation, and proper treatment of periodontal disease of natural teeth are needed for maintaining the implants in these observed subjects.

Adolescent↗

PubMed2001

[Studies on epidemic feature of enteric adenoviruses infection in feces of infants with diarrhea in Shenzhen].

OBJECTIVE: To estimate the enteric adenoviruses infection in feces of infants with diarrhea in Shenzhen. METHODS: All 195 fecal samples of infants were tested by PCR. Amplimers were analysed by Rsa I endonucleases and the type of enteric adenovirus identified. RESULTS: The positive rate of adenovirus DNA in fecal samples was 13.33% (26/195) while the prevalence rates of enteric adenovirus type 40, adenovirus type 41 and the other type of adenovirus were 2.56% (5/195), 8.21% (16/195) and 2.56% (5/195) respectively. Fever was the characteristic symptom of adenovirus infection. CONCLUSION: Enteric adenovirus type 40 and 41 were important pathogens which caused infant diarrhea in Shenzhen, with latter the majorty.

Adenoviridae Infections↗

PubMed2001

[GATA-2 gene expression in leukemia patients and its significance].

OBJECTIVE: To investigate GATA-2 gene expression in leukemia patients and its clinical significance. METHODS: GATA-2 gene transcripts were detected by reverse transcriptase polymerase chain reaction (RT-PCR), and bcr/abl or PML/RAR alpha transcripts were detected in patients with chronic myeloid leukemia (CML) and acute promyelocytic leukemia (APL), respectively. RESULTS: The GATA-2 transcripts were revealed in 93% of acute myeloid leukemia (AML), in 70% of acute lymphoblastic leukemia (ALL), and 83% of CML patients, but not in normal bone marrow and peripheral blood cells. GATA-2 expression in remission patients was similar to newly diagnosed or relapsed patients. In post-transplantation patients, GATA-2 expression was significantly decreased. In these cases GATA-2 transcripts could be detected with bcr/abl fusion gene disappeared in 2 of 12 CML, whereas neither GATA-2 nor PML/RARalpha transcripts could be detected in APL. CONCLUSION: GATA-2 transcripts was highly expressed in leukemia patients and had no change in remission but significantly decreased in post-transplantation patients. Detection of GATA-2 expression would give information about the residual leukemia stem cells.

Bone Marrow Cells↗

PubMed2001

The affects of acupuncture at sibai and neiting acupoints on gastric peristalsis.

The frequency and amplitude of gastric peristaltic wave were significantly changed in 15 subjects when Sibai (ST 2) and Neiting (ST 44) acupoints of the Stomach Channel of Foot-Yangming were punctured. The results demonstrate that these acupoints are effective for treatment of stomach diseases, providing an experimental basis for the theory of channels and collaterals.

Acupuncture Points↗

PubMed2001

[IL-2 gene and cisplatin combined therapy for head and neck squamous cell carcinoma].

OBJECTIVE: The objective of this study is to assess the efficacy of IL-2 gene and cisplatin combined therapy on murine HNSCC models. METHODS: HNSCC tumors were established in murine models. The sizes of tumors were measured before and after combined IL-2 and cisplatin treatment, and the results were evaluated by comparing different single treatment groups and the control IL-2 expression was measured after IL-2 gene transfer. Cytotoxic T-lymphocyte (CTL) and natural killer (NK) assays were also performed. RESULTS: HNSCC tumor growth was significantly inhibited following combined IL-2 gene and cisplatin therapy, when compared with that of the control. The levels of IL-2 protein expressions were increased in combined and single IL-2 treated groups. The activities of cytotoxic T-lymphocytes and natural killers in both the combined treatment group and the IL-2 treated group are higher than those of the controlled group. CONCLUSION: Combined IL-2 gene and cisplatin therapy can significantly inhibit HNSCC tumor growth in the murine models, and efficiently induces anti-tumor immune reaction of hosts.

Animals↗

PubMed2001

[Influence of the hearing loss level and auditory sensation curve type on click evoked SP/AP amplitude ratio in Menière's disease].

OBJECTIVE: To assess the influence of hearing loss level and auditory sensation curve type on click evoked SP/AP amplitude ratio (negative summating potential/action potential) in the diagnosis of Meniere's disease. METHOD: AP and SP was recorded with tympanic ECochG in normal controls (50 ears), patients with sensorineural hearing loss (SNHL) and patients with Meniere's disease (90 ears) which were further divided based upon the degree of hearing loss and audiometric configuration. SP/AP amplitude ratio was calculated and analyzed. RESULT: AP latency in the three groups had no significant differences. AP amplitude in normal hearing subjects was higher than other two patients groups (P < 0.05). Amplitude of SP of control group was higher than that of SNHL group (P < 0.01), but lower than Meniere's disease group (P < 0.01). SP/AP amplitude ratio in Meniere's disease ears was (48.09 +/- 14.83)%, which was significantly higher than that of SNHL group (20.20 +/- 15.00)% (P < 0.01) and normal group (23.85 +/- 8.05)% (P < 0.01). In Meniere's disease ears, SP/AP amplitude ratio was positively correlated to pure tone thresholds (r = 0.5601 P < 0.01). An elevated SP/AP ratio was found in 73% of the Meniere's ears and 6% of the SNHL ears. SP/AP ratio among the different levels of hearing loss in Meniere's disease ears, of the ears with mild hearing loss was lower than those with moderate (P < 0.01) and severe hearing loss (P < 0.01), but between later groups there was no statistical significant difference (P > 0.05). Positive rate of SP/AP ratio was 63% in mild, 83% in moderate, 73% in severe hearing loss ears respectively. SP/AP amplitude ratio in patients with low tone auditory curve type was lower than that with flat type(P < 0.05), the latter had no significant difference (P > 0.05) compared with high tone type. Positive rate was 67.57% in low tone type, 75% in high tone type and 78% in flat tone type respectively. CONCLUSION: Results suggests the increase of SP/AP ratio was of clinical significance in the diagnosis of Meniere's disease, and was with advancing pure tone thresholds in certain range of hearing loss levels. Click evoked SP/AP amplitude ratio was affected by degree of hearing loss and auditory sensation curve as well, perhaps the influence of the former on SP/AP ratio was considerable significant.

Action Potentials↗

PubMed2001

[Determination of inorganic anions in beer and brewing water by ion chromatography].

An ion chromatography method was used to determine fluoride, chloride, nitrite, dihydrogen phosphate, nitrate and sulfate anions in beer and brewing water on a YSA8 8022A-9(250 mm x 4 mm i.d.) separation column, with sodium carbonate-sodium bicarbonate buffer as mobile phase and an electrical conductivity cell as detector. Qualitative analysis was performed with retention time and stanard spiking method, and quantitative analysis was conducted with a calibration curve by measuring the peak height. This method is simple, rapid and accurate.

Anions↗

PubMed2001

[The study on effects of rhEGF on proliferation of human conjunctival epithelial cells].

PURPOSE: To investigate the effects of Recombinant Human Epidermal Growth Factor (rhEGF) on proliferation of human conjunctival epithelial cells and optimal dose in vitro. METHODS: Cultured human conjunctival epithelial cells were plated in 96-well plates at a density of 2,000 cells per chamber, treated with different concentrations of rhEGF (100 micrograms/ml, 50 micrograms/ml, 20 micrograms/ml, 10 micrograms/ml, 5 micrograms/ml and 1 microgram/ml). After 24, 48, 72 and 96 hours of treatment, cell viability was assessed with MTT assay. RESULTS: There was no significant difference in all experimental groups and the control group in the first 24 horus. Experimental groups at a concentration of 50 micrograms/ml, 20 micrograms/ml and 10 micrograms/ml had significantly higher cell viability than which of the control group 48 hours later. All groups of rhEGF had significantly higher cell viability than which of the control group after 72 hours treatment, except for 100 micrograms/ml of rhEGF. Each group of rhEGF after 96 hours treatment had higher cell viability than which of the control group, and 100 micrograms/ml of rhEGF had lower cell viability than which of the other experimental groups, with significant difference. CONCLUSION: rhEGF enhance proliferation of human conjunctival epithelial cells effectively in vitro. The optimal concentration ranged from 10 micrograms/ml to 50 micrograms/ml.

Cell Division↗

PubMed2001

[Construction of recombinant plasmids containing genes of HBsAg and their expression in the eukaryotic cells].

OBJECTIVE: To construct recombinant plasmids expressing L, M, S and pre-S1-S protein of HBsAg. METHODS: Amplifying segments of S, pre-S2-S, pre-S1-pre-S2-S genes of HBV by PCR and amplifying segment of pre-S1-S by overlap extension PCR; inserting the segments into Rc/CMV and pSG5UTPL/Flag plasmids respectively and exploring their expressions by Western-Blot hybridization, identifying the inserting segments by sequencing. RESULTS: The sequences of the inserted segments were the same as the genes of S, pre-S2-S, pre-S1-pre-S2-S and pre-S1-S and the results of Western-Blot hybridization were positive for the aimed proteins. CONCLUSION: We have gained 8 recombinant plasmids expressing S, M, L and pre-S1-S proteins with high efficacy.

Base Sequence↗

PubMed2001

[The protein expression of p53 and bcl-2 in laryngeal squamous cell carcinoma].

OBJECTIVE: To detect the relationship of p53 and bcl-2 gene to laryngeal carcinoma. METHODS: p53 and bcl-2 protein expressions were examined in the specimens of 60 laryngeal carcinomas and 8 vocal cord polyps by immunohistochemistry method. RESULTS: Overexpressions of p53 and bcl-2 were found in the laryngeal carcinoma specimens; the positive rates of p53 and bcl-2 protein expression were 61.7%(37/60) and 43.3%(26/60), respectively. Negative results were observed in all the vocal cord polyp specimens. The positive rates of p53 and bcl-2 expression were related to the histological grade and cervical lymphatic metastasis of laryngeal carcinoma but not related to clinical stage and tumor types. CONCLUSION: The results of this study support the hypothesis that p53 and bcl-2 gene may be involved in the apoptosis of laryngeal carcinoma and they may play an important role in the pathogenesis of laryngeal cancer.

Adult↗

PubMed2001

[The effects of adenosine, interleukin-1 and theophylline on the expression of A2 adenosine receptor mRNAs in peripheral blood mononuclear cells from asthmatic patients].

OBJECTIVE: To explore the roles of A2a and A2b adenosine receptors(A2aAR and A2bAR) in the pathogenesis of bronchial asthma. METHODS: Eleven asthmatics and 11 healthy subjects were included in this investigation. Peripheral blood mononuclear cells(PBMCs) were obtained after density centrifugation on Ficoll-Hypaque. The expression of A2aAR and A2bAR mRNAs in PBMCs was examined by use of the reverse transcription-polymerase chain reaction (RT-PCR) and image pattern analysis semiquantitation method. RESULTS: The expression of A2aAR mRNA in PBMCs from asthmatics was not enhanced, compared with that of healthy subjects(P > 0.05). Adenosine or IL-1 or theophylline was not observed to have effect on A2aAR mRNA (P > 0.05). A2bAR gene expression in PBMCs was more markedly in patients with asthma than in normal individuals (P < 0.05). Adenosine and IL-1 significantly increased A2bAR mRNAs in asthmatics. Theophylline inhibited A2bAR gene expressions. The expression of A2bAR mRNA in PBMCs was positively correlated to serum total immunoglobulin E (TIgE) level in asthmatics (r = 0.72, P < 0.01). The expressions of A2bAR mRNA elevated by adenosine or IL-1 were correlated positively with serum TIgE(r = 0.78 or r = 0.61; P < 0.05) and negatively with the forced expiratory volume in first second to predicted value ratio (FEV1%) (r = -0.62 or r = -0.81; P < 0.05) in asthmatics. CONCLUSION: These results indicated that the expression of A2bAR mRNAs in PBMCs was more remarkable in asthmatics than in healthy subjects; that adenosine or IL-1 potentiated the mRNA expression of A2bAR in PBMCs in asthmatic patients, which was correlated with allergy state and the degree of airway obstruction; and that theophylline might antagonize adenosine by inhibiting A2bAR mRNA.

Adenosine↗

PubMed2001

[Human papilloma virus infection and expression of p16 protein in laryngeal papilloma and laryngeal carcinoma].

OBJECTIVE: To evaluate the role of human papilloma virus (HPV) infection and inactivation of p16 gene in laryngeal papilloma (LP) and laryngeal squamous cell carcinoma (LC). METHODS: HPV consensus primers direct in situ polymerase chain reaction (ISPCR) and immunohistochemical method were applied to detect the presence of HPV genomes (1, 6, 8, 11, 13, 16, 18, 30, 31, 32, 33, 45, 51) and the expression of p16 protein respectively in 93 cases of formalin-fixed, paraffin-imbedded specimens, which contained 46 cases of LPs [adult-onset laryngeal papilloma (ALP) 21, juvenile-onset laryngeal papilloma (JLP)25], 26 cases of LCs, 6 cases of normal tissues adjacent to carcinoma, and 15 cases of vocal noduli. RESULTS: (1) The difference of positive rates of HPV-DNA in JLP group (84%, 21/25) and other groups were statistically significant (chi 2 test, P < 0.05). The difference of positive rates of HPV-DNA in ALPs(38.1%, 8/21), in LCs(19.2%, 5/26), in vocal noduli(0%, 0/15), and in normal tissues adjacent to carcinoma(0%, 0/6) were not significant statistically (chi 2 test or Fisher's exact probability test, P > 0.05). (2) The positive rates of expression of p16 protein in ALP group(57.1%, 12/21) and LC group(38.5%, 10/26) were significantly lower than that in vocal nodule group(93.3%, 14/15), in JLP group(88%, 22/25), and in normal tissues adjacent to carcinoma group (100%, 6/6) (chi 2 test or Fisher's exact probability test, P > 0.05). There were no significant differences of positive rates of expression of p16 protein between ALP group and LC group, and between JLP group and vocal nodule group (chi 2 test, P > 0.05). (3) In LPs, the difference of positive rates of p16 protein expression between HPV positive cases and HPV negative cases was significant statistically (chi 2 test, P < 0.05). In LCs, there was no difference in p16 protein expression rate between the two teams(Fisher exact probability test, P > 0.05). CONCLUSION: The pathogenesis of JLP is closely associated with HPV infection and not associated with the inactivation of p16 gene. Conversely, the pathogenesis of ALP and LC is associated with the inactivation of p16 gene and not associated with the HPV infection.

Adult↗

PubMed2001

[Intact-bridge tympanomastoidectomy procedure: a reasonable option in the surgery of chronic otitis media and mastoiditis with cholesteatoma and/or granulation tissue].

OBJECTIVE: To study and evaluate a surgical option for the treatment of otitis media and mastoiditis with cholesteatoma and/or granulation tissue. METHODS: The procedure is called intact-bridge tympanomastoidectomy (IBM). There are some modifications for the treatment of patients suffered from chronic otitis media and mastoiditis with cholesteatoma and/or granulation tissue. The features of IBM include: 1. the aditus, mastoid and attic opened and the intractable pathological tissues eradicated thoroughly. 2. the posterior tympanal space opened through the facial recess if necessary. 3. a widened middle ear space by lowering bony bridge established. 4. the adults blocked. 5. immediate or staging tympanoplasties conducted according to the conditions of mucosa in the tympanum. RESULTS: The modified IBM procedure was performed on 62 ears from 61 cases. The follow-up has been 12-38 months and more than two years in 51 ears. The dry ear was obtained within 5-13 weeks with an average of 6 weeks. In 24.2% of ears the air-bone gap(ABG) was 20dB HL or less and within 21-30 dB HL in 41.9% of ears, the ABG over 31 dB HL was 16.1%. CONCLUSION: Our results indicate that IBM procedure fulfills the desired purposes of both open- and close-cavity techniques, the thorough eradication of diseased tissue allow to get a dry ear and restoration of hearing. IBM, therefore, is a reasonable choice for the surgery of otitis media and mastoiditis with cholesteatoma and/or granulation tissue.

Adolescent↗

PubMed2001

[Determining the site of airway obstruction in obstructive sleep apnea with airway pressure measurements during sleep].

OBJECTIVE: Determine the site(s) of upper airway obstruction and the influence of sleep stage on the pattern of obstruction with upper airway (UA) pressure measurement. Analyses the clinical value of UA pressure measurement and it's influenced factors. METHODS: 30 OSAS patients underwent UA pressure measurement during polysomnography. Multisensory pressure catheters with five solid-state ultraminiature sensors were insert through patients' upper airway to esophagus, The sensors were located at the nasopharynx, oropharynx, tongue base, hypopharynx and esophagus and the lower limit of UA obstruction was determined relying on the observed pressure pattern. RESULTS: (1) During inspiration, obstruction occurred associated with a increased negative inspiratory pressure inferior to the site of obstruction and a disappeared negative inspiratory pressure above the site of obstruction. (2) Three patterns of obstruction were observed. 1. The site of obstruction was located at the level of the palate. 2. The level of the palate and tonguebase obstruction all present. 3. Nasopharyngeal obstruction soft plate obstruction and tongue-pharynx obstruction all present. (3) The factors which affected these measurement are 1. The catheter were placed by observation with a fiberoptic endoscope to keep the sensors located at the correct position. 2. Catheter plugging with secretions need to be prevented. CONCLUSION: UA pressure measurement can objectively identify the level of obstruction during sleep.

Adult↗

PubMed2001

[FTIR study on the normal and cancerous stomach tissues].

Tissues of cancerous and corresponding normal stomach were studied by FTIR technique. The results showed that there are obvious differences between FTIR spectra of them in spectral parameters such as frequency, intensity and band shape etc. The changes involving the phosphate symmetric stretching nu s, PO2- and asymmetric stretching nu as, PO2- modes, the CH3 and CH2 groups stretching (nu s, CH2, nu as, CH3) and bending (delta CH2) modes and the C-O stretching nu C-O mode were discussed. In addition, the changes of structure of hydrogen-bonding of nucleic acid and cell proteins and the packing and the conformational structure of the membrance lipids were analysed further. The average wavenumber of band of nu s, PO2- shifted from 1,080.92 cm-1 to 1,085.93 cm-1 and that of nu as, PO2- shifted from 1,239.64 cm-1 to 1,238.73 cm-1 which indicated that the degree of hydrogen-bonding formed by oxygen atom of the phosphodiester groups of nucleic acids was increased. The average wavenumber of band of delta CH2 of membrance lipids shifted from 1,455.23 cm-1 to 1,457.37 cm-1 that suggested that the conformational structure of the methylene chains of membrance lipids is more disordered than in normal tissues. The shift of band of nu C-O of cell proteins from 1,166.08 cm-1 to 1,166.58 cm-1 indicated that the hydrogen-bond of cell proteins become weaker.

Adenocarcinoma↗

PubMed2000

Delineation of the roles of amino acids involved in the catalytic functions of Leuconostoc mesenteroides glucose 6-phosphate dehydrogenase.

The roles of particular amino acids in substrate and coenzyme binding and catalysis of glucose-6-phosphate dehydrogenase of Leuconostoc mesenteroides have been investigated by site-directed mutagenesis, kinetic analysis, and determination of binding constants. The enzyme from this species has functional dual NADP(+)/NAD(+) specificity. Previous investigations in our laboratories determined the three-dimensional structure. Kinetic studies showed an ordered mechanism for the NADP-linked reaction while the NAD-linked reaction is random. His-240 was identified as the catalytic base, and Arg-46 was identified as important for NADP(+) but not NAD(+) binding. Mutations have been selected on the basis of the three-dimensional structure. Kinetic studies of 14 mutant enzymes are reported and kinetic mechanisms are reported for 5 mutant enzymes. Fourteen substrate or coenzyme dissociation constants have been measured for 11 mutant enzymes. Roles of particular residues are inferred from k(cat), K(m), k(cat)/K(m), K(d), and changes in kinetic mechanism. Results for enzymes K182R, K182Q, K343R, and K343Q establish Lys-182 and Lys-343 as important in binding substrate both to free enzyme and during catalysis. Studies of mutant enzymes Y415F and Y179F showed no significant contribution for Tyr-415 to substrate binding and only a small contribution for Tyr-179. Changes in kinetics for T14A, Q47E, and R46A enzymes implicate these residues, to differing extents, in coenzyme binding and discrimination between NADP(+) and NAD(+). By the same measure, Lys-343 is also involved in defining coenzyme specificity. Decrease in k(cat) and k(cat)/K(m) for the D374Q mutant enzyme defines the way Asp-374, unique to L. mesenteroides G6PD, modulates stabilization of the enzyme during catalysis by its interaction with Lys-182. The greatly reduced k(cat) values of enzymes P149V and P149G indicate the importance of the cis conformation of Pro-149 in accessing the correct transition state.

Arginine↗

PubMed2000

A tetravalent single-chain antibody-streptavidin fusion protein for pretargeted lymphoma therapy.

Single-chain Fv antibody fragments from the CD20-specific murine monoclonal antibody B9E9 were genetically engineered as streptavidin fusions [single-chain Fv-streptavidin (scFvSA) fusion protein] for use in pretargeted radioimmunotherapy. The scFvSA constructs were expressed as soluble, tetrameric species in the periplasm of Escherichia coli. Expression levels were affected by the order of the variable regions and the length and composition of the single-chain Fv linker. The best expressor was obtained with the variable regions in the heavy chain-light chain configuration separated by a 25-mer Gly4Ser linker. This construct produced 250-300 mg of soluble, tetrameric fusion protein per liter of fermentor culture. The fusion protein (Mr 173,600) was purified from crude lysates by iminobiotin affinity chromatography with an overall yield of about 50% and was analyzed for functionality both in vitro and in vivo. Immunoreactivity of the scFvSA fusion protein and its nanomolar affinity to CD20-positive Ramos cells were comparable with the B9E9 monoclonal antibody. The fusion protein had a biotin dissociation rate identical to recombinant streptavidin and bound an average of 3.6 biotins/molecule of a possible 4 biotins/molecule. Labeled fusion protein cleared from the blood of BALB/c mice with a P half-life of about 16 h. In nude mice bearing Ramos xenografts, the fusion protein demonstrated sufficient tumor localization of functional streptavidin to enable efficient, tumor-specific targeting of a subsequently administered radionuclide-chelate/biotin molecule. These results suggest that large quantities of functional scFvSA can be produced for clinical testing as a therapy for non-Hodgkin's lymphoma.

Amino Acid Sequence↗