Biomedical subjects

R Fung

Publications and source records attributed to R Fung.

5 recordsLinked to original sources

PubMed1999

Multimerin processing by cells with and without pathways for regulated protein secretion.

Multimerin is a massive, soluble, homomultimeric, factor V-binding protein found in platelet alpha-granules and in vascular endothelium. Unlike platelets, endothelial cells contain multimerin within granules that lack the secretory granule membrane protein P-selectin, and in culture, they constitutively secrete most of their synthesized multimerin. To further evaluate multimerin's posttranslational processing and storage, we expressed human endothelial cell prepromultimerin in a variety of cell lines, with and without pathways for regulated secretion. The recombinant multimerin produced by these different cells showed variations in its glycosylation, proteolytic processing, and multimer profile, and human embryonic kidney 293 cells recapitulated multimerin's normal processing for constitutive secretion by human endothelial cells. When multimerin was expressed in a neuroendocrine cell line capable of regulated protein secretion, it was efficiently targeted for regulated secretion. However, the multimerin stored in these cells was proteolyzed more extensively than normally occurs in platelets, suggesting that endoproteases similar to those expressed by megakaryocytes are required to produce platelet-type multimerin. The impact of the tissue-specific differences in multimerin's posttranslational processing on its functions is not yet known. Multimerin's sorting and targeting for regulated secretion may be important for its functions and its association with factor V in secretion granules.

Blood Platelets↗

PubMed1999

Characterization of a novel trypanosome lytic factor from human serum.

Natural resistance of humans to the cattle pathogen Trypanosoma brucei brucei has been attributed to the presence in human serum of nonimmune factors that lyse the parasite. Normal human serum contains two trypanosome lytic factors (TLFs). TLF1 is a 500-kDa lipoprotein, which is reported to contain apolipoprotein A-I (apoA-I), haptoglobin-related protein (Hpr), hemoglobin, paraoxonase, and apoA-II, whereas TLF2 is a larger, poorly characterized particle. We report here a new immunoaffinity-based purification procedure for TLF2 and TLF1, as well as further characterization of the components of each purified TLF. Immunoaffinity-purified TLF1 has a specific activity 10-fold higher than that of TLF1 purified by previously described methods. Moreover, we find that TLF1 is a lipoprotein particle that contains mainly apoA-I and Hpr, trace amounts of paraoxonase, apoA-II, and haptoglobin, but no detectable hemoglobin. Characterization of TLF2 reveals that it is a 1,000-kDa protein complex containing mainly immunoglobulin M, apoA-I, and Hpr but less than 1% detectable lipid.

Amino Acid Sequence↗

PubMed1998

Studies of multimerin in human endothelial cells.

Multimerin is a novel, massive, soluble protein that resembles von Willebrand factor in its repeating, homomultimeric structure. Both proteins are expressed by megakaryocytes and endothelial cells and are stored in the region of platelet alpha-granules resembling Weibel-Palade bodies. These findings led us to study the distribution of multimerin within human endothelial cells. Multimerin was identified in vascular endothelium in situ. In cultured endothelial cells, multimerin was identified within round to rod-shaped, dense-core granules, some of which contained intragranular, longitudinally arranged tubules and resembled Weibel-Palade bodies. However, multimerin was found primarily in different structures than the Weibel-Palade body proteins von Willebrand factor and P-selectin. After stimulation with secretagogues, multimerin was observed to redistribute from intracellular structures to the external cellular membrane, without detectable accompanied secretion of multimerin into the culture media. In early passage endothelial cell cultures, multimerin was associated with extensive, fibrillary, extracellular matrix structures, in a different distribution than fibronectin. Although multimerin and von Willebrand factor are stored together in platelets, they are mainly found within different structures in endothelial cells, indicating that there are tissue-specific differences in the sorting of these soluble, multimeric proteins.

Blood Proteins↗

PubMed1984

Review of cyanoacrylate tissue glues with emphasis on their otorhinolaryngological applications.

Cyanoacrylates were first synthesized by Ardis in 1949. However, it was not until Coover in 1959 discovered their adhesive properties that an interest arose in using these substances in surgical procedures. Over the past two decades the use of cyanoacrylates has been varied and widespread among the surgical specialties. methyl 2-cyanoacrylate (Eastman 910 Monomer), Isobutyl-cyanoacrylate (Bucrylate), and 2-cyano-butyl-acrylate (Histoacryl) were the most widely used. Because of its tissue toxicity methyl 2-cyanoacrylate was discarded. The consensus of various investigators was that the higher homologues, in particular Histoacryl could be safely used in human applications. The authors thought it would be important to ascertain how the academic departments of Otolaryngology perceived the role of cyanoacrylates within their specialty. A questionnaire was distributed to 115 academic centers: 47% of the departments responded and, of those, 34% indicated a current working knowledge of the cyanoacrylates. This response confirmed a very active interest in these tissue adhesives despite a lack of F.D.A. approval. The otologic applications of these adhesives has been well documented, but the literature is devoid of studies using cyanoacrylates in other aspects of Otolaryngology. The authors feel that these adhesives (in particular Histoacryl) have a role as an adjunctive technique in facial reconstructive and cosmetic surgery for autogenous cartilage grafting. A study using rabbits was designed to determine if Histoacryl could be used safely to overcome the technical difficulties (graft migration during healing and cartilage fracture during suturing) often encountered when performing autogenous onlay cartilage grafting. On the left ear of each rabbit, a cartilage graft was harvested and reimplanted at a second site on the same ear by suturing the perichondrium of the graft to the perichondrium of the donor site. On the right ear the graft was secured to the donor site with Histoacryl. The histological analysis of the rabbits' ears sacrificed at weekly intervals from 1 week to 1 month failed to demonstrate cartilage damage or tissue toxicity in the ears where Histoacryl was used. In conclusion, the authors contend that a role exists for the use of Histoacryl as an adjunctive technique in facial reconstructive and cosmetic surgery. The study will be continued to assess the long-term results of using Histoacryl for autogenous onlay cartilage grafting.

Animals↗

PubMed1978

ABO blood groups in Chilean and Peruvian mummies. II. Results of agglutination-inhibition technique.

ABO blood groups of Peruvian and Chilean mummies were determined with the agglutination-inhibition method. In Peru all ABO blood groups were found in the period from 3000 B.C. to 1400 A.D.; from this period to 1650 only A and O were seen. In Chile no B or AB was noted either in pre-Columbian or Colonial mummies. This confirms the archeological concept that the Chilean Indian was culturally as well as genetically different from the Peruvian Indian. Further studies using other genetic markers are in order, as well as changing certain preconceived notions on blood groups of American Indians.

ABO Blood-Group System↗