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Biomedical subjects

W T Liu

Publications and source records attributed to W T Liu.

125 records · Page 7Linked to original sources
PubMed1983

Studies on demyelination in vitro: the requirement of membrane attack components of the complement system.

Anti-spinal cord antibodies (anti-SC) cause demyelination of well myelinated mouse cerebellum cultures in the presence of fresh serum. Heating the serum for 30 min at 56 degrees C abolishes the demyelinating activity. We studied the role of complement (c) in demyelination initiated by anti-SC in well myelinated mouse cerebellum cultures. Demyelination was assessed morphologically. The extent of demyelination was correlated to the dose of whole serum C as well as the dose of antibody. To evaluate the requirement of membrane attack components of C, C5b-C9, sister cultures were treated with antibody + C8 deficient human serum (C8D-HS) with and without purified human C8. Extensive demyelination was observed in C8-reconstituted cultures whereas antibody + C8D-HS did not demyelinate, indicating the essential requirement of C5b-8, and/or C5b-9. Extensively demyelinated cultures remyelinated when fresh medium was supplied, suggesting that the process of antibody and C-mediated demyelination is selective for myelin membrane in this system.

Animals↗
PubMed1978

Psychiatric consultation in a Vietnamese refugee camp.

The authors provided psychiatric consultation to medical personnel in charge of a Vietnamese refugee camp in California. Although the emergency measures that supplied clothing, food, shelter, and medical care to nearly 60,000 refugees were immensely successful, consultation was requested to assist with selected mental health problems. The recommendations of the consulting team were related to the stage of camp development: early recommendations concerned easing adaptation to the camp setting; later efforts included creating a psychiatric crisis clinic and carrying out a mental health survey on a random sample of refugees. The results of this survey helped camp directors to understand how refugees responded to the camp experience.

Adaptation, Psychological↗
PubMed1977

Reverse transcriptase of foamy virus. Purification of the enzymes and immunological identification.

Reverse transcriptase from foamy virus, strain H4188 was estimated and purified. The enzyme has the following characteristics: 1. The reaction utilized preferentially oligo (dT) poly (rA) as a primer-template; however, the synthetic primer-template oligo (dT) poly (dA) could also be used to some extent. 2. The reaction utilized oligo (dG) poly (rC) as a primer-template with very low efficiency. 3. The crude virus preparation had a detectable endogenous reaction using the four deoxyribonucleotides for DNA polymerization. 4. The cation requirement for the enzyme reaction was much more biased for Mn++ than for Mg++ ions. 5. The molecular weight of the partially-purified enzyme was estimated to be about 80,000. Aggregates of 240,000 daltons were also seen. The activity of this enzyme was not inhibited by antisera against the reverse transcriptases of various type C RNA viruses, namely, feline endogenous leukemia virus, RD 114, Woolly simian sarcoma virus (SSV-1) and avian myeloblastosis virus (AMV). Antiserum against Rauscher leukemia virus (RLV) enzyme was marginally active against foamy virus enzyme, perhaps indicating a slight cross-reaction. The biochemical characteristics of foamy virus reverse transcriptase seemed to be very close to those of the type C RNA viruses, but the immunological reaction proved that the foamy virus reverse transcriptase was distinct from the others.

Epitopes↗
PubMed1977

Properties of RBL-5 leukemia cells cultivated in vitro.

RBL-5 leukemia induced by Rauscher murine leukemia virus (R-MuLV) carried in the ascites form in C57BL/6 mice was cultivated in vitro and passaged continuously. Both low- and high-passage cells released the same level of murine leukemia virus, as detected by the XC plaque assay. Membrane antigens of the cultivated cells were also detected by the indirect immunofluorescence assay. Both low- and high-passage cells showed the same activity of antigen detectable by anti-R-MuLV serum, whereas only the high-passage cells reacted strongly against a syngeneic antiserum to RBL-5 crude membrane (CM). The oncogenicity of the low and high passages of the cultivated cells was compared with the ascites cells. The results indicated that the oncogenic potential of the cells gradually decreased during in vitro passage. The accumulation or retention of CM antigen on the membrane of the high-passage cells suggested that their decreased oncogenic potential might be due to increased immunogenicity and/or immunosensitivity. This strengthened the hypothesis that the cellular transplantation antigens are not identical to type C viral antigens, since the R-MuLV antigens were not altered during passage in vitro.

Animals↗
PubMed1975

An electron microscopic study of the structural polymorphism of hepatitis B antigen from human sera.

The physical features of hepatitis B antigen (HBAg) particles from human sera are investigated with electron microscopy and immune electron microscopic technique. All the virus-like particles are pleomorphic in structure; although they are classified into two categories: HBsAg and HBcAg by immunological technique. The small, spherical particles measured in a range of 16 to 30 nm in diameter, mostly 20 to 22 nm,are populous in the positive serum. The tubular particles have the width of 18 to 22 nm and the length of 50 to 230 nm or even longer. Sometimes these particles contain a larger end and become the tadpole shape. The large particles or Dane particles measured mainly 42 nm in diameter have an inner core and the outer coats. The inner core of 27 nm in diameter can expose spontaneously. It can be released from the coats by heating at 56 degrees C for 30 min or by treatment of Tween 80 (1%) at room temperature. When specific antibody is added in the positive sample, the aggregate of the antigen-antibody clumping can be revealed with electron microscope. The core antigen of the large particles may attach to the molecular protein of the antibody and show the spike-like structure. This polymorphism of HBAg particles seems unique in animal virology. The roles of these particles played in medical and virological fields are discussed.

Antigen-Antibody Complex↗
PubMedDate not supplied

Lack of serum neutralizing antibody against poliovirus in patients with juvenile distal spinal muscular atrophy of upper extremities.

Serum neutralizing antibodies for type 1, 2 and 3 poliovirus were studied in 15 Chinese patients in Taiwan with juvenile distal spinal muscular atrophy of the upper extremities and 15 age-matched normal subjects. Significantly lower serum antibody titers were found in the study group, suggesting that patients with this chronic focal form of acquired motor neuron disease are, to some degree, immunologically unresponsive to the neutralizing epitope of poliovirus.

Adolescent↗