26
|
Lai PH, Chen PC, Pan HB, Yang CF. Venous infarction from a venous angioma occurring after thrombosis of a drainage vein. AJR Am J Roentgenol 1999; 172:1698-9. [PMID: 10350326 DOI: 10.2214/ajr.172.6.10350326] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
27
|
Lai PH, Chen C, Liang HL, Pan HB. Hyperintense basal ganglia on T1-weighted MR imaging. AJR Am J Roentgenol 1999; 172:1109-15. [PMID: 10587157 DOI: 10.2214/ajr.172.4.10587157] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
28
|
Lai PH, Ho JT, Wang JS, Pan HB. Cervical radiculopathy due to epidural varicose veins. AJR Am J Roentgenol 1999; 172:841-2. [PMID: 10063901 DOI: 10.2214/ajr.172.3.10063901] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
29
|
Li JY, Lai PH, Lam HC, Lu LY, Cheng HH, Lee JK, Lo YK. Hypertrophic cranial pachymeningitis and lymphocytic hypophysitis in Sjögren's syndrome. Neurology 1999; 52:420-3. [PMID: 9932974 DOI: 10.1212/wnl.52.2.420] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The authors describe a patient with primary Sjögren's syndrome who developed pachymeningitis, hypopituitarism, and central diabetes insipidus. The patient improved with corticosteroid pulse therapy.
Collapse
|
30
|
Lai PH, Yang CF, Pan HB, Chen C, Lo YK, Hung KH. Intracranial acute arterial ischemia of the anterior circulation: evaluation with three-dimensional time-of-flight magnetic resonance angiography. ZHONGHUA YI XUE ZA ZHI = CHINESE MEDICAL JOURNAL; FREE CHINA ED 1999; 62:20-7. [PMID: 10063708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
BACKGROUND Stroke has been the second most common cause of death, after cancer, in Taiwan since 1983. The cost of stroke to society in terms of morbidity, mortality and economics is profound. Heightened interest in the early diagnosis and treatment of acute stroke challenges neuroimagers to optimize available modalities and to develop new techniques for the evaluation of cerebrovascular disease. The aim of this study was to investigate the effectiveness of magnetic resonance angiography (MRA) in conjunction with spin-echo imaging in patients with acute brain infarction of the anterior circulation. METHODS Magnetic resonance imaging and three-dimensional Fourier transformed time-of-flight MRA studies, performed on 50 patients within one week after the onset of cerebral ischemia, were retrospectively reviewed and correlated with clinical records. Five of the 50 MRAs were considered nondiagnostic and excluded because of poor patient cooperation. RESULTS In 41 of the 45 cases, the area of infarct corresponding to the clinical deficit at the time of study was identified on T2-weighted spin-echo images. Arterial occlusions or severe stenoses that corresponded to ischemic manifestations were identified with MRA in 37 of the 45 patients. A focal discontinuity with decreased arterial caliber corresponded to stenosis and nonvisualization of distal branches represented arterial occlusion. MRA provided information for 23 cases not obtained from the MR images. CONCLUSIONS Vascular lesions demonstrated on intracranial MRA show a high correlation with infarct distribution. MRA, which provides information adjunctive to conventional MR imaging in a majority of cases, is concluded to be an important component of the complete evaluation of brain infarction.
Collapse
|
31
|
Lai PH, Hsu SS, Pan HB, Yang CF. Intracranial cystic cavernous angioma: a case report. Kaohsiung J Med Sci 1998; 14:593-8. [PMID: 9796205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
We present a case of cystic cavernous angioma in an 18-year-old woman with the chief complaint of acute onset of seizures. Computed tomography (CT) and magnetic resonance (MR) imaging revealed a tumor with a slightly enhanced solid calcified portion and a large cystic portion. The patient was well without recurrence 6 months after surgery. The importance of MR imaging in the differential diagnoses is emphasized.
Collapse
|
32
|
Lai PH, Yang CF, Huang CH, Yeh LR, Lin SL, Pan HB. Primary intracranial leiomyoma: case report. Neuroradiology 1998; 40:238-41. [PMID: 9592794 DOI: 10.1007/s002340050574] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We present a case of intracranial parenchymal leiomyoma in a 20-year-old woman with a chief complaint of numbness and a painful sensation over the right limbs for several years. CT and MRI revealed an intensely enhancing calcified mass. The patient was well, without recurrence, 2 years after surgery.
Collapse
|
33
|
Chang MH, Chiang HT, Lai PH, Sy CG, Lee SS, Lo YY. Putaminal petechial haemorrhage as the cause of chorea: a neuroimaging study. J Neurol Neurosurg Psychiatry 1997; 63:300-3. [PMID: 9328243 PMCID: PMC2169723 DOI: 10.1136/jnnp.63.3.300] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES A hyperintense putamen on either CT or MRI as a finding associated with chorea has occasionally been described and is almost always associated with non-ketotic hyperglycaemia. The cause of the hyperintensity of the striatum in these images is still controversial. Some reports have found that calcification was responsible whereas others have advocated petechial haemorrhage as the cause. The purpose of this study was to determine whether hyperintense striata are caused by petechial haemorrhage or calcification, with the sequential imaging changes. SUBJECTS AND METHODS Five patients presenting with an acute onset of either hemichorea or generalised chorea and showed either unilateral or bilateral hyperdense striatum on the initial CT were assessed. Neuroimaging studies including sequential CT and MRI examinations and detailed biochemical tests were performed. RESULTS Three patients had pronounced hyperglycaemia and the other two patients had no biochemical abnormalities. In all patients, the first CT scans, performed within two weeks of the onset of chorea, showed a high density over the striatum contralateral to the chorea, which diminished or disappeared two months later. T1 weighted imaging disclosed hypersignal intensities over the striatum contralateral to the chorea on admission which diminished two months later. T2 weighted imaging at two months showed hyposignal intensity changes corresponding to the area with hypersignal changes on T1 weighted images, implying haemosiderin deposition. CONCLUSION Based on the evolution of clinical manifestations and the findings of neuroimaging, putaminal petechial haemorrhage might be a new entity causing either hemichorea or generalised chorea.
Collapse
|
34
|
Lai PH, Lin SM, Pan HB, Yang CF. Disseminated miliary cerebral candidiasis. AJNR Am J Neuroradiol 1997; 18:1303-6. [PMID: 9282859 PMCID: PMC8338024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We present a case of disseminated intracranial infection by Candida albicans in a 5-year-old girl who had fever and a change of consciousness after surgery for complex congenital heart malformation. MR imaging revealed multiple small ring-enhancing hemorrhagic abscesses. One year after antifungal treatment, the abscesses and ventriculomegaly were almost completely resolved. The patient was discharged in a stable but vegetative condition.
Collapse
|
35
|
Hung KH, Chang MH, Lai PH, Shy CG, Lo YK. Traumatic dissection of the vertebral artery: a case report. ZHONGHUA YI XUE ZA ZHI = CHINESE MEDICAL JOURNAL; FREE CHINA ED 1997; 59:210-5. [PMID: 9198299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This report concerns a patient suffering from a severe neck pain on the third day after a traffic accident. This condition was followed by a lateral medullary infarction on the next day. One week later, he was transferred to this hospital and dissection of the vertebral artery was disclosed. It should be emphasized that in case of acute cervical spine injury or severe neck pain after a major trauma, vertebral artery dissection should be considered, as its early diagnosis may have crucial therapeutic implications. In addition, the advantages of the combination of magnetic resonance imaging and magnetic resonance angiography as diagnostic tools-of-choice are emphasized.
Collapse
|
36
|
Tien RD, Lai PH, Smith JS, Lazeyras F. Single-voxel proton brain spectroscopy exam (PROBE/SV) in patients with primary brain tumors. AJR Am J Roentgenol 1996; 167:201-9. [PMID: 8659372 DOI: 10.2214/ajr.167.1.8659372] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE The Single-Voxel Proton Brain Exam (PROBE/SV) is an automated MR spectroscopic technique. The purpose of this study was to investigate the use of PROBE/SV as a diagnostic tool in patients with primary brain tumors and to compare our findings with the known information obtained from conventional nonautomated MR spectroscopic techniques. SUBJECTS AND METHODS We used PROBE/SV to image 10 normal adults and 46 patients with primary brain tumors: 29 glioblastoma multiformes (GBMs), five anaplastic astrocytomas, and 12 low-grade astrocytomas. All studied were performed on a 1.5-T Signa unit. Average voxel sizes were 6-8 cm3. A corresponding point-resolved spectroscopy spectrum was obtained from normal-appearing brain parenchyma in each patient for comparison with the spectra from known areas of pathology. RESULTS In patients with low-grade gliomas (grades 1 and 2), we observed decreased N-acetylaspartate (12 of 12) and slightly increased choline (11 of 12) when we compared these metabolites with those in the spectra of patients' normal brains. This comparison in patients with GBM yielded markedly decreased N-acetylaspartate (29 of 29) and prominently increased choline (27 of 29). In the short TE spectra, we frequently saw lipid signal in high-grade tumors, especially in GBMs (12 of 20). We identified lactate peaks in high-grade tumors (anaplastic astrocytoma and GBM, 29 of 34) and also in low-grade tumors (four of 12). The creatine signal in all gliomas was slightly less than that of healthy brain tissue. The lowest N-acetylaspartate, choline, and creatinine levels in conjunction with the highest lactate levels were usually found in necrotic portions of high-grade tumors. CONCLUSION PROBE/SV is a simplified MR spectroscopy technique that reduces setup time and provides automatic on-line data processing and display. The voxel location can be selected to focus on the area of interest and to minimize voxel contamination from unwanted tissue. The results from our experimentation with PROBE/SV in patients with brain tumors generally concur with published reports of tumor spectra obtained by conventional MR spectroscopic techniques. The ease and accuracy of this new technique make it a useful clinical tool in differentiating human brain tumor grades.
Collapse
|
37
|
Lai PH, Tien RD, Chang MH, Teng MM, Yang CF, Pan HB, Chen C, Lirng JF, Kong KW. Chorea-ballismus with nonketotic hyperglycemia in primary diabetes mellitus. AJNR Am J Neuroradiol 1996; 17:1057-64. [PMID: 8791916 PMCID: PMC8338595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE To describe the neuroimaging (Ct, MR, and single-photon emission CT [SPECT]) findings in a series of patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus and to correlate the imaging findings with the clinical presentation. METHODS The neuroimaging and clinical data from 10 patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus were evaluated. Family and drug histories, as well as other causes of chorea, were excluded. All 10 patients had CT, 5 also had MR imaging, and 3 had SPECT examinations. Three had follow-up CT and MR imaging studies, and MR findings were correlated with CT findings in 5 cases. Two experienced neuroradiologists, aware of the diagnosis but blinded to the clinical status of the patients, evaluated all images and reached a consensus as to the final interpretation. RESULTS CT studies in 9 of 10 patients showed a hyperdense putamen and/or caudate nucleus; in 1, the CT findings were normal. T1-weighted MR images in all 5 patients who had MR imaging (including the patient with a normal CT study) showed hyperintense lesions without significant T2 signal alternation at the basal ganglia. In all 3 of the patients who had SPECT studies of the brain, the scans revealed hypoperfusion at corresponding areas. All 3 follow-up studies depicted resolution of the lesions in the abnormal basal ganglia. Increased hypointensity on T2-weighted and gradient-echo T2*-weighted images was also observed in the sequential MR images. In all patients, the initial side of involvement correlated well with the neuroimaging findings. The chorea resolved within 2 days after treatment of the hyperglycemia in 9 patients. CONCLUSION In patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus, CT and T1-weighted MR images show unilateral or bilateral lesions of the putamen and/or caudate. SPECT scans show hypoperfusion. These findings may be related to petechial hemorrhage and/or myelin destruction. Early recognition of these imaging characteristics may facilitate diagnosis of primary diabetes mellitus with hyperglycemia and prompt appropriate therapy.
Collapse
|
38
|
Lai PH, Chang JM, Hou YY, Chu ST, Lin SL, Yang CF. Carcinosarcoma of the salivary gland on CT. AJNR Am J Neuroradiol 1995; 16:1733-5. [PMID: 7502984 PMCID: PMC8337751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Three cases of carcinosarcoma of the salivary gland, two in the submandibular gland, and one in the parotid, were investigated with CT and exhibited a variety of findings. The density of the tumors was lower than that of normal submandibular tissue. A calcification was found in one case. One case showed extensive lymphadenopathy. The parotid lesion had low central density with an enhancing margin.
Collapse
|
39
|
Chang MH, Chang TW, Lai PH, Sy CG. Resting tremor only: a variant of Parkinson's disease or of essential tremor. J Neurol Sci 1995; 130:215-9. [PMID: 8586989 DOI: 10.1016/0022-510x(95)00033-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Resting tremor is one of the characteristic features of Parkinson's disease. However, there are a number of patients who typically have resting tremor alone for at least 5 years without development of other parkinsonian signs or symptoms. The etiology of an isolated resting tremor is still obscure. Recently, positron emission tomography was used to study these patients with isolated resting tremor, and demonstrated a markedly decreased striatal uptake of fluoro-dopa to the range of Parkinson's disease. These findings suggested the existence of a separate subtype, namely, tremulous Parkinson's disease with a manifestation of resting tremor alone. In order to confirm the existence of this subgroup of tremulous Parkinson's disease and further investigate its morphological changes and the usefulness of magnetic resonance imaging, we collected 5 patients who typically have resting tremor for at least 8 years in the absence of other features of Parkinson's disease. MRI was performed and the results of the images showed typical findings of Parkinson's disease with smudging or decreased distance between substantia nigra and red nucleus. Quantitative analysis also demonstrated a significant decrease of the above-noted distance when the resting tremor group was compared to the essential tremor group. Therefore, patients with an isolated resting tremor can have morphological abnormalities in addition to functional disturbances shown by positron emission tomography. To our knowledge, this is the first paper to report that resting tremor is a variant of Parkinson's disease rather than essential tremor, by using a double-blind method, with magnetic resonance imaging to support.
Collapse
|
40
|
Chang JY, Schindler P, Ramseier U, Lai PH. The disulfide folding pathway of human epidermal growth factor. J Biol Chem 1995; 270:9207-16. [PMID: 7721838 DOI: 10.1074/jbc.270.16.9207] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Human epidermal growth factor (EGF) contains three disulfides and 53 amino acids. Reduced/denatured EGF refolds spontaneously in vitro to acquire its native structure. The mechanism of this folding process has been elucidated by structural analysis of both acid and iodoacetate trapped intermediates. The results reveal that the folding is accompanied by a sequential flow of unfolded EGF (0-disulfide) through three groups of folding intermediates, namely 1-disulfide, 2-disulfide, and 3-disulfide (scrambled) EGF isomers, to reach the native structure. Equilibrium occurs among isomers of each class of disulfide species, and the composition of intermediates appears to be highly heterogeneous. Together, at least 27 fractions of folding intermediates have been identified, but there exist only limited numbers of well populated species which constitute more than 80% of the total intermediates found during EGF folding. Six species of such well populated intermediates have been isolated, which included two 1-S-S, two 2-S-S, and two 3-S-S scrambled species. Their disulfide structures have been identified here. Both 1-S-S isomers are found to contain non-native disulfides. One of the 2-S-S species consists of two non-native disulfides and the other admits two native disulfides. Among the six disulfides of the two scrambled species, only one is native. Together, native disulfides constitute 25% of the total disulfides found in these six well populated intermediates. These results contrast sharply to those observed with bovine pancreatic trypsin inhibitor, which has shown that well populated folding intermediates consist of exclusively native disulfides (Weissman, J. S., and Kim, P. S. (1991) Science 253, 1386-1393). We propose that well populated folding intermediates, regardless of whether they contain native or non-native disulfides, do not necessarily represent the productive species and specify the folding pathway. Furthermore, conditions influencing the efficiency of EGF folding have been investigated. It is demonstrated here that under optimized compositions of redox agents, including the use of cysteine/cystine and protein disulfide isomerase, the in vitro folding of EGF could be achieved quantitatively within 1 min.
Collapse
|
41
|
Wu MT, Pan HB, Lai PH, Chang JM, Tsai SH, Wu CW. CT of gastritis cystica polyposa. ABDOMINAL IMAGING 1994; 19:8-10. [PMID: 8161914 DOI: 10.1007/bf02165852] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Gastritis cystica polyposa (GCP) is an uncommon lesion that usually occurs at the gastroenterostomy site, although occasionally it can be found in an unoperated stomach. We present a rare case of GCP which presented as a large polypoid mass in the gastric fundus and contained cystic components demonstrable on preoperative computed tomography.
Collapse
|
42
|
Arakawa T, Narachi MA, Hsu YR, Everett RR, Lai PH, Fish EN. The effect of C-terminal processing on the activity of human interferon-gamma. DRUG DESIGN AND DELIVERY 1989; 4:217-25. [PMID: 2518759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Homogeneous recombinant human interferon-gamma (IFN-gamma) obtained from Escherichia coli (E. coli) was treated with a protease-containing fraction prepared from mechanically lysed E. coli cells. Polyacrylamide gel electrophoresis of the resulting product revealed two major components of molecular weight less than that of intact IFN-gamma. These were purified by ion exchange chromatography in the presence of 7 M urea and shown to have intact IFN-gamma N-terminal sequences, suggesting that they resulted via C-terminal cleavages of IFN-gamma. Amino acid analysis indicated that 4 C-terminal residues of IFN-gamma were lacking in one, and 15 in the other. The species lacking 4 C-terminal residues had activities virtually indistinguishable from those of IFN-gamma in antiviral and growth inhibitory assays using Encepharomyocarditis-treated HeLa or T98G cells and in a macrophage activation assay using macrophage-like U937 cells. The species lacking 15 C-terminal residues had markedly decreased activities in each of these assays, and had decreased binding affinity for IFN-gamma cell surface receptors. These observations define the C-terminal residues important for IFN-gamma's biological activity--information which should be useful in designing analogs of IFN-gamma with enhanced or altered biological activities.
Collapse
|
43
|
Lu HS, Boone TC, Souza LM, Lai PH. Disulfide and secondary structures of recombinant human granulocyte colony stimulating factor. Arch Biochem Biophys 1989; 268:81-92. [PMID: 2463792 DOI: 10.1016/0003-9861(89)90567-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Molecular characteristics and secondary structures of recombinant methionyl human granulocyte colony stimulating factor produced by genetically engineered Escherichia coli are described. Limited radiolabeling of the protein with tritiated iodoacetate and determination of the labeled residue revealed that this recombinant protein contains only one free cysteine at position 17 which is not essential for activity. The free cysteine is inaccessible to modification unless the molecule is unfolded under denaturing conditions. The molecule forms two disulfide bridges which were assigned as Cys(36)-Cys(42) and Cys(64)-Cys(74) based on the results of isolation and characterization of disulfide-containing peptides obtained from a subtilisin digest of the intact protein. CD analyses and secondary structure prediction suggest that the molecule is abundant in alpha-helical structures.
Collapse
|
44
|
Klein ML, Bartley TD, Lai PH, Lu HS. Structural characterization of recombinant consensus interferon-alpha. J Chromatogr A 1988; 454:205-15. [PMID: 3235597 DOI: 10.1016/s0021-9673(00)88614-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Recombinant consensus interferon-alpha is derived from genetically modified Escherichia coli containing a synthetic gene constructed from a consensus of interferon sequences. The purified and biologically active protein has been subjected to detailed structural characterization including sequence determination and peptide isolation and identification. The homogeneous consensus interferon-alpha preparation contains two chromatographically indistinguishable homologous polypeptides with one containing an extra methionyl residue at the amino terminus. The delineated amino acid sequence of the protein is identical to that expected from the coding sequence of the gene. Correct oxidation of the molecule has been confirmed with two intramolecular disulfide linkages observed at Cys(1)-Cys(99) and Cys(29)-Cys(139).
Collapse
|
45
|
Tsai LB, Lu HS, Kenney WC, Curless CC, Klein ML, Lai PH, Fenton DM, Altrock BW, Mann MB. Control of misincorporation of de novo synthesized norleucine into recombinant interleukin-2 in E. coli. Biochem Biophys Res Commun 1988; 156:733-9. [PMID: 3056402 DOI: 10.1016/s0006-291x(88)80904-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Interleukin-2 produced from a recombinant E. coli was found to contain as much as 19% norleucine in place of methionine in a minimal medium fermentation. Medium supplementation experiments and use of a leucine-requiring mutant host strain indicated the origin of norleucine to be de novo biosynthesis by reactions involving the enzymes of the leucine biosynthetic pathway. The misincorporation was highly suppressed by addition of either L-leucine or L-methionine to the fermentation and completely suppressed by adding both amino acids.
Collapse
|
46
|
Lu HS, Tsai LB, Kenney WC, Lai PH. Identification of unusual replacement of methionine by norleucine in recombinant interleukin-2 produced by E. coli. Biochem Biophys Res Commun 1988; 156:807-13. [PMID: 3056404 DOI: 10.1016/s0006-291x(88)80916-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Moderate amounts of norleucine incorporation into recombinant interleukin-2 (IL-2) produced in E. coli have been detected. Incorporation of norleucine occurs both at the amino terminal and internal methionines as confirmed by the isolation of norleucine-containing tryptic peptides which eluted later than the respective methionine-containing peptides by reverse-phase HPLC. The occurrence of norleucine in intact protein and modified peptides was determined by amino acid analysis and amino acid sequencing including Edman degradation and fast atom bombardment mass spectrometry. In the subsequent paper, we determined that norleucine incorporation is caused by the endogenous synthesis of norleucine in E. coli.
Collapse
|
47
|
Lu HS, Klein ML, Lai PH. Narrow-bore high-performance liquid chromatography of phenylthiocarbamyl amino acids and carboxypeptidase P digestion for protein C-terminal sequence analysis. JOURNAL OF CHROMATOGRAPHY 1988; 447:351-64. [PMID: 3225285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Carboxypeptidase P digestion followed by narrow-bore high-performance liquid chromatography of phenylthiocarbamyl amino acids is employed for polypeptide C-terminal end group and sequence determination. Carboxypeptidase P digestion of polypeptides provides specific cleavage of protein C-terminal amino acids. The digestion offers the advantage that it can be carried out in either 10 mM sodium acetate or water at pH 4.0 in the presence of an enzyme activator, Brij-35. The narrow-bore high-performance liquid chromatography of all 20 phenylthiocarbamyl-amino acids has provided quantitative analysis at low picomole levels. This efficient and sensitive procedure is particularly useful for examining in vivo excision of protein C-termini and for verifying the integrity of various protein products produced by recombinant DNA techniques.
Collapse
|
48
|
Weinstein J, Lee EU, McEntee K, Lai PH, Paulson JC. Primary structure of beta-galactoside alpha 2,6-sialyltransferase. Conversion of membrane-bound enzyme to soluble forms by cleavage of the NH2-terminal signal anchor. J Biol Chem 1987; 262:17735-43. [PMID: 3121604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
This report describes the primary structure of a rat liver beta-galactoside alpha 2,6-sialyltransferase (EC 2.4.99.1), a Golgi apparatus enzyme involved in the terminal sialylation of N-linked carbohydrate groups of glycoproteins. The complete amino acid sequence was deduced from the nucleotide sequence of cDNA clones of the enzyme. The primary structure suggests that the topology of the enzyme in the Golgi apparatus consists of a short NH2-terminal cytoplasmic domain, a 17-residue hydrophobic sequence which serves as the membrane anchor and signal sequence, and a large lumenal, catalytic domain. NH2-terminal sequence analysis of a truncated form of the enzyme, obtained by purification from tissue homogenates, reveals that it is missing a 63-residue NH2-terminal peptide which includes the membrane binding domain. These and supporting results show that soluble forms of the sialyltransferase can be generated by proteolytic cleavage between the NH2-terminal signal-anchor and the catalytic domain.
Collapse
|
49
|
Paulson JC, Weinstein J, Ujita EL, Riggs KJ, Lai PH. The membrane-binding domain of a rat liver Golgi sialyltransferase. Biochem Soc Trans 1987; 15:618-20. [PMID: 3315771 DOI: 10.1042/bst0150618] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
50
|
Langley KE, Lai PH, Wypych J, Everett RR, Berg TF, Krabill LF, Davis JM, Souza LM. Recombinant-DNA-derived bovine growth hormone from Escherichia coli. 2. Biochemical, biophysical, immunological and biological comparison with the pituitary hormone. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 163:323-30. [PMID: 3816808 DOI: 10.1111/j.1432-1033.1987.tb10803.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Bacterially synthesized, recombinant-DNA-derived bovine growth hormone (r-bGH), prepared as described in the preceding paper in this journal, has been characterized in comparison with pituitary bovine growth hormone (pit-bGH). The characterization criteria include sodium dodecyl sulfate/polyacrylamide gel electrophoresis, automated N-terminal sequence analysis, amino acid composition, isoelectric focusing, reverse-phase high-performance liquid chromatography, ultraviolet absorbance, analysis for free protein thiol, sizing by gel filtration, circular dichroism, radioimmunoassay and biological activity in the hypophysectomized rat weight-gain assay. In every respect the r-bGH appears to be virtually identical to pit-bGH.
Collapse
|