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Biomedical subjects

J J Lin

Publications and source records attributed to J J Lin.

At least 217 records · Page 12Linked to original sources
PubMed1981

Disruption of the in vivo distribution of the intermediate filaments in fibroblasts through the microinjection of a specific monoclonal antibody.

Monoclonal antibodies (JLB1 and JLB7) that recognize minor components of the intermediate filament system of cultured cells were introduced into living fibroblasts by microinjection. Several minutes after injection of the JLB7 antibody virtually all of the intermediate filaments of the cells were found to be aggregated into tight bundles near or around the nucleus. In contrast, injection of the JLB1 antibody caused little or no aggregation of the intermediate filaments. Electron microscopy showed that the perinuclear bundles that formed after injection of the JLB7 antibody each consisted of ten or more filaments apparently crosslinked together. Double-label immunofluorescence microscopy showed that virtually all of the vimentin-containing intermediate filaments in the JLB7 antibody-injected cells were redistributed to the perinuclear region and remained there for at least 24 hr. The distributions of actin microfilaments and microtubules were seemingly undisturbed following microinjection. No obvious changes in cell morphology or behavior were apparent in the cells injected with JLB7 antibody; the cells displayed a flat appearance, showed a polarity, were able to ruffle and bleb and even appeared to show the normal saltatory movements of intracellular vesicles, granules and mitochondria, suggesting that intermediate filaments are not involved in these activities. The microinjection of highly specific monoclonal antibodies that recognize and alter components of the cell provides an additional approach to determine the in vivo functions of intracellular elements.

Animals↗
PubMed1981

Monoclonal antibodies against myofibrillar components of rat skeletal muscle decorate the intermediate filaments of cultured cells.

Monospecific antibodies were produced in vitro by fusing mouse myeloma cells with spleen cells from a BALB/c mouse immunized with rat skeletal myofibrils. After cloning 3 times on agarose, two stable clones were obtained and chosen for further characterization. The first clone, JLB1, produced an antibody that recognizing an antigen distributed in the M-line region and on either site of the Z line of myofibrils. The second clone, JLB7, produced an antibody reacting only with an antigen located at the M-line region of myofibrils. Both JLB1 and JLB7 antibodies decorate the typical intermediate filaments of a variety of cultured cells. Colcemid treatment of cells before reaction with both antibodies resulted in the coiling or capping (or both) of the fibers around the nucleus. Brief treatment of cells with cytochalasin B did not affect the integrity of the fibers stained by both antibodies whereas, under the same conditions, microfilament bundles visualized by another monoclonal antibody (JLA20) against actin were disassembled into many aggregates in the cytoplasm. Identical staining patterns of the intermediate filaments are obtained by double-label immunofluorescence microscopy of the same cell stained with these monoclonal antibodies and rabbit autoimmune serum (which has been shown to react with the components of the intermediate filaments). By using immunoprecipitation, protein bands at 210,000 and 95,000 daltons from chicken embryo fibroblasts were identified as the potential antigens recognized by JLB1 and JLB7 monoclonal antibodies, respectively. The widespread occurrence of these antigenic determinants in different cultured cells suggests the highly conservative property of these intermediate-filament components.

Animals↗
PubMed1981

Osteoid osteoma: an unusual presentation.

An osteoid osteoma developed in the fracture callus four years after an open reduction and internal fixation of a femur of a 21-year-old man. The treatment consisted of en bloc excision of the lesion using intraoperative roentgenographic studies for localization of the lesion.

Adult↗
PubMed1980

Pseudolymphoma of the breast. I. In a study of 8,654 consecutive tylectomies and mastectomies.

Pseudolymphoma is a benign pathological process that morphologically resembles malignant lymphoma. Its occurrence in the mammary tissue has been described but has not been well investigated. We conducted a prospective and retrospective study of 8,654 consecutive mastectomies and tylectomies of the breast and found only 9 cases (0.1%) of primary lymphoreticular lesions. Of these 9, 5 were pseudolymphomas; 3, histiocytic lymphomas; and 1, Hodgkin's disease. Clinically, pseudolymphoma of the breast was described as an enlarging mass giving a dull, aching sensation. A history of physical trauma to the affected area could be traced in 3 patients with certainty. The mean patient age of the entire series was 36 years. Grossly, the tumor was a solid, firm nodule without any evidence of fibrocystic disease. Microscopically, it showed a lymphoid infiltrate with a nodular pattern. Three of the 5 cases revealed distinct germinal centers. Atypical lymphoid cells were not observed in any of these cases. After local excision, no patients had recurrence over a period of two to eight years. In view of a history of trauma, accompany fat necrosis in some cases, IgG gammopathy, it is postulated that pseudolymphoma of the breast, probably akin to pseudolymphoma of the lung, may represent an overwhelming local response to an injury. This lesion, reactive in nature, should be differentiated from a malignant lymphoma so that patients are not subjected to unnecessary mastectomy, radiation, or chemotherapy.

Adult↗
PubMed1980

Assembly of outer membrane lipoprotein in an Escherichia coli mutant with a single amino acid replacement within the signal sequence of prolipoprotein.

We have compared the rate of assembly of outer membrane proteins including the lipoprotein in a pair of isogenic mlpA+ (lpp+) and mlpA (lpp) strains by pulse-chase experiments. The rate of assembly of the mutant prolipoprotein into the outer membrane was slightly slower than that of the wild-type lipoprotein. The rate of assembly of protein I and protein H-2 was similar in the wild type and the mutant, whereas the rate of assembly of protein II into the outer membrane was slightly reduced in the mutant strain. The organization of outer membrane was slightly reduced in the mutant strain. The organization of outer membrane proteins in the mutant cells appeared not to be grossly altered, based on the apparent resistance (or susceptibility) of these proteins toward trypsin treatment and their resistance to solubilization by Sarkosyl. Like the wild-type lipoprotein, the mutant prolipoprotein in the outer membrane was resistant to trypsin. On the other hand, the prolipoprotein in the cytoplasmic membrane fraction of the mutant cell envelope was susceptible to trypsin digestion. We conclude from these data that proteolytic cleavage of prolipoprotein is not essential for the translocation and proper assembly of lipoprotein into outer membrane.

Amino Acids↗
PubMed1978

An Escherichia coli mutant with an amino acid alteration within the signal sequence of outer membrane prolipoprotein.

Lipoprotein has been purified from an Escherichia coli strain carrying a mutation in the structural gene for murein lipoprotein (mlpA). Amino acid analysis of the purified mutant lipoprotein indicates that the mutant lipoprotein corresponds to the uncleaved prolipoprotein with a single amino acid replacement of glycine with aspartic acid. Automated Edman degradation has established the precise location of this amino acid substitution to be at the 14th residue of the prolipoprotein. This alteration in the signal sequence of prolipoprotein results in a failure of the mutated prolipoprotein to be processed. Furthermore, the structural alteration in the mutant lipoprotein appears also to have affected its topological localization in the mutant cell. Whereas lipoprotein in the wild-type strain is exclusively located in the outer membrane of the cell envelope, the membrane-bound lipoprotein in this mutant is recovered in both the inner and outer membranes of the cell envelope. The data suggest, however, that proteolytic cleavage of prolipoprotein to form mature lipoprotein is not essential for the translocation and assembly of lipoprotein into the outer membrane.

Amino Acid Sequence↗
PubMed1978

Pericardial angiosarcoma simulating pericardial effusion by echocardiography.

A fast-growing angiosarcoma caused incapacitation of a boy and death in a period of three months. The growth of the tumor was well documented by a series of echocardiograms. The heart was well encased by a thick layer of purplish vascular neoplasm enveloped mostly by thin pericardium, with some additional few foci of extracardiac metastasis. The heart weighed 2,000 gm. It is worthy to note that another cause of an echo-free space may be the presence of a pericardial tumor, rather than pericardial effusion.

Adolescent↗
PubMed1977

Biochemical characterization of a mutant lipoprotein of Escherichia coli.

A lipoprotein mutant of E. coli K-12 has been characterized. The mutant lipoprotein was found to differ from the wild-type lipoprotein in the following respects: (i) it is present in an appreciable amount in the soluble fraction (275,000 X g supernatant); (ii) it lacks the covalently-linked diglyceride; (iii) it contains an unmodified cysteine which can be carboxymethylated in vitro; (iv) it undergoes dimerization and the dimer can be converted into monomeric form by reduction with 2-mercaptoethanol; (v) both the monomeric form and especially the dimeric form of the mutant lipoprotein migrate more slowly than the corresponding forms of wild-type lipoprotein in sodium dodecyl sulfate/urea polyacrylamide gel electrophoresis; and (vi) the mutant lipoprotein is not assembled into the murein sacculi, and this results in a greatly reduced amount of bound-form lipoprotein in the mutant. These data strongly suggest that the mutation has affected the primary structure of lipoprotein, in such a way that it is not modified normally, leading to the production of a structurally-altered lipoprotein deficient in covalently-linked lipid as well as a defective assembly of the altered lipoprotein into the rigid layer of the cell envelope.

Bacterial Proteins↗