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S H Yu

Publications and source records attributed to S H Yu.

At least 55 records · Page 3Linked to original sources
PubMed1990

Role of bovine pulmonary surfactant-associated proteins in the surface-active property of phospholipid mixtures.

The surfactant-associated proteins, SP-A, SP-B and SP-C have been isolated from bovine pulmonary surfactant. The biophysical roles of SP-B and SP-C in reconstituted surfactants, with various phospholipid mixtures subjected to different thermal treatments, have been examined using a pulsating bubble surfactometer. The phospholipid mixtures were: (A) dipalmitoylphosphatidylcholine (DPPC)/egg phosphatidylcholine (PC)/egg phosphatidylglycerol (PG) (6:2:2, w/w); (B) DPPC/PG (9:1); and (C) DPPC/PG (7:3). Thermal treatments involved mixing SP-B or SP-C, at room temperature, with lipids in chloroform/methanol (9:1, v/v) and removing the solvent under N2 by (1) evaporation at room temperature; (2) evaporation at 45 degrees C; or (3) incubation at 45 degrees C overnight prior to evaporation at 45 degrees C. In all cases, 45 degrees C solvent evaporation was the most effective treatment. DPPC/egg PG (7:3) was the most favourable lipid composition. With either a static or a pulsating bubble, SP-C promoted a rapid decrease in surface tension with little change thereafter. This implies that SP-C is effective in enhancing phospholipid adsorption but does not play an important role in the removal of non-DPPC lipid from the monolayer. While SP-B was not as effective in facilitating phospholipid absorption, samples containing this protein could achieve near zero surface tension upon pulsation. A very low surface tension could also be attained during the initial pulsation of DPPC/PG plus SP-B mixtures which had been allowed to adsorb until equilibrium. This observation indicates that SP-B promotes the removal of PG from the monolayer. SP-A alone had only a slight effect on the surface activity of the DPPC/PG (7:3) mixture, and did not accelerate adsorption of samples containing SP-C. However, SP-A facilitated phospholipid adsorption and may also enhance the removal of PG from monolayers in the presence of SP-B.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1990

[A new solution of simultaneous equations and its application in assay of compound preparations].

A new solution of simultaneous equations in spectrophotometry is studied. Owing to replacing the absorption coefficients by the absorption ratios, the authors have obtained rather greater accuracy from Vierordt's method than hitherto. A further development of the same formulation has led to a simple theoretical criterion, which enables the analyst to avoid pairs of wavelengths that are unsatisfactory for precision. This new method has been applied to the assay of compound injection of sodium benzoate and caffeine and compound tablet of amidopyrine and caffeine with satisfactory results.

Aminopyrine↗
PubMed1990

The treatment of mesangial IgA nephropathy with cyclophosphamide, dipyridamole and warfarin: a two-year prospective trial.

Of 52 patients with mesangial IgA nephropathy, 25 were allocated to treatment with cyclophosphamide (6 months), and dipyridamole and warfarin (2 years) and 27 to no treatment in a randomized prospective 2-year study. At entry, the treated and untreated groups of patients did not differ in mean serum creatinines, urinary protein excretions, quantitative urinary erythrocyte counts or blood pressure readings. At the end of the trial mean (+/- SEM) serum creatinine values had gone from 0.12 +/- 0.01 to 0.13 +/- 0.01 mmol/l (p less than 0.05) in untreated patients and from 0.10 +/- 0.01 to 0.12 +/- 0.01 mmol/l (p less than 0.05) in treated patients. Mean (+/- SEM) log values of urinary erythrocyte (rbc) counts had not changed significantly from 5.47 +/- 0.09 to 5.21 +/- 0.14 log rbc/ml in untreated patients, from 5.45 +/- 0.11 to 5.49 +/- 0.19 log rbc/ml in treated patients. However, in treated patients, mean (+/- SEM) urinary protein excretions decreased from 1.67 +/- 0.35 to 1.15 +/- 0.31 g/24 h (p less than 0.01) whereas in untreated patients urinary protein was unchanged between initial values of 1.76 +/- 0.34 and follow-up at 1.89 +/- 0.45 g/24 h. No significant changes in blood pressure occurred in either group. This study supports the observation that treatment of IgA nephropathy with cyclophosphamide, dipyridamole and warfarin is associated with a reduction of urinary protein excretion but a significant effect on preservation of renal function, at least as determined by serum creatinine values, could not be confirmed over this two-year study.

Adult↗
PubMed1990

Failure to induce resistance of Schistosoma japonicum to praziquantel.

In order to explore the possible occurrence of inducing resistance of Schistosoma japonicum to praziquantel (PZQ), a set of animal experiments were carried out. Outbred mice (NIH strain), Anhui isolates of S. japonicum and Oncomelania hupensis were used. In one protocol five weeks after being infected with 48-52 cercariae, mice were orally dosed with PZQ 300 mg/kg, and killed 82 days later to isolate eggs from the liver. Snails were exposed to miracidia released from egg-hatching. F1 progeny were thus obtained through cercarial inoculation. The same scheme was applied for the establishment of the F2 generation. In another protocol two weeks after infection, PZQ 50 mg/kg/day was given to mice for 5 days. Eggs were collected 26-27 days post treatment and the identical procedures were adopted for F1 and F2 generations successively. Analysis of total worm and female worm reduction rates indicated that there was no significant difference between the sensitivity to PZQ of F1 and F2 progenies of S. japonicum and the parent worms.

Animals↗
PubMed1989

Structural relationship between the two small hydrophobic apoproteins in bovine pulmonary surfactant.

Lipid extracts of bovine pulmonary surfactant contain two very hydrophobic surfactant-associated proteins (SP) designated SP-B (15 kDa nonreduced) and SP-C (3.5 kDa). These two low molecular weight apoproteins were delipidated and purified on silica SEP-PAK cartridges using various reagents. Dansylation studies revealed that the 15 kDa apoprotein has three N-termini: Phe, Leu and Ile, while the 3.5 kDa apoprotein has two N-termini: Leu and Ile. In either protein, only a very small amount of N-Ile is present. Quantitative N-terminal dansylation analysis of the 15 kDa protein indicated that Phe and Leu (plus Ile) are present in a 1:1 ratio. Carboxy-terminal analysis showed that the 15 kDa protein contains C-terminal Gly, and the 3.5 kDa protein contains C-terminal Leu. Gas-phase amino terminal sequencing of the 15 kDa protein revealed almost exclusively the Phe-polypeptide (SP-B). These results suggest that the 15 kDa apoprotein is not an oligomer of SP-B and SP-C. The reason that analysis of SP-B reveals N-terminal Leu and Ile by dansylation which cannot be confirmed by amino acid sequencing is not known.

Amino Acid Sequence↗
PubMed1989

Effect of surfactant-associated protein-A (SP-A) on the activity of lipid extract surfactant.

The properties of natural bovine surfactant and its lipid extract have been examined with a pulsating bubble surfactometer which assesses the ability of surfactant lipids to adsorb to the air/liquid interface and reduce the surface tension to near 0 dynes/cm during dynamic compression. Studies conducted at 1 mg/ml phospholipid revealed that the surface activity (i.e., the ability to produce low surface tensions) of lipid extracts could be enhanced by incubating the sample at 37 degrees C for 120 min or by addition of CaCl2. In contrast, incubation at 37 degrees C only slightly improved the biophysical activity of natural surfactant and the addition of CaCl2 had a more modest effect than with lipid extracts. With 20 mM CaCl2, the surfactant activity of lipid extract surfactant was similar to that of natural surfactant. Incubation with EDTA reduced the biophysical activity of natural surfactant. Experiments in which increasing amounts of lipid extract were replaced by natural surfactant revealed that small amounts of natural surfactant enhanced the surfactant activity of lipid extract. The biophysical activity of lipid extract surfactant was also increased by the addition of soluble surfactant-associated protein-A (SP-A) (28-36 kDa) purified from natural bovine surfactant. These results indicate that SP-A (28-36 kDa) improves the surfactant activity of lipid extracts by enhancing the rate of adsorption and/or spreading of phospholipid at the air/liquid interface resulting in the formation of a stable lipid monolayer at lower bulk concentrations of either phospholipid or calcium.

Animals↗
PubMed1989

Functional human CD4 protein produced in milk of transgenic mice.

The soluble form of human CD4, an HIV receptor molecule first detected on the surface of T cells, binds glycoprotein gp120, a coat protein of human immunodeficiency virus, and has potential value for the treatment of AIDS. As a first step toward providing the necessary quantities of this protein at an affordable price we report here on the production of functional, soluble human CD4 in transgenic mice. In these animals, a regulatory region derived from a murine gene encoding the whey acidic protein directs synthesis of human CD4 protein to the mammary gland of lactating animals where it is secreted into milk.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Construction and screening of Plasmodium falciparum cDNA library.

The HAINAN isolate of Plasmodium falciparum FCC1/HN was cultured in vitro in large quantities. The total parasite mRNA was purified and reverse transcribed into cDNA. The cDNA fragments were inserted into lambda gt11 to construct a P. falciparum FCC1/HN erythrocytic stage cDNA library. Inhibitory monoclonal antibodies (McAbs) M26-32, F6-C2, and F6-D3 were used to screen the cDNA library expressed in E. coli. A total of 27 positive clones were found to react with M26-32 alone and 34 clones with both M26-32 and F6-C2. These expressed proteins may be candidates for use in malaria vaccine.

Animals↗
PubMed1988

Comparative studies on the biophysical activities of the low-molecular-weight hydrophobic proteins purified from bovine pulmonary surfactant.

Two low-molecular-weight hydrophobic proteins with nominal molecular weights Mr = 15,000 and Mr = 3,500 have been isolated from the lipid extracts of bovine pulmonary surfactant by several methods, including (a) dialysis plus silicic acid chromatography, (b) elution from Waters SEP-PAK silica cartridges with a variety of solvent mixtures, and (c) ultrafiltration. As detailed in the text, these proteins have been designated surfactant-associated protein-BC (SP-BC) (15 kDa: nonreduced), and SP-C (3.5 kDa). The biophysical activities of reconstituted surfactant containing these proteins and the phospholipids present in lung surfactant have been compared with the biophysical activities of bovine lipid extract surfactant on a pulsating bubble surfactometer using a phospholipid concentration of 10 mg/ml. At this concentration, unmodified lipid extract surfactant reduces the surface tension of the pulsating bubble to near 0 within 10 pulsations at 20 cycles per min. Similar biophysical properties were observed with modified lipid extract surfactant in which the relative concentration of hydrophobic protein had been reduced from 1 to 0.4% (W/W) of the phospholipids by addition of dipalmitoylphosphatidylcholine (DPPC) or DPPC plus phosphatidylglycerol. Reconstituted surfactants, which contained partially delipidated SP-BC (15 kDa: nonreduced) obtained by method (a) at a relative concentration of 0.1%, were also capable of reducing the surface tension to near 0 mN/m. Preparations of SP-BC (15 kDa: nonreduced) obtained by method (b), which had been subjected to very low pH levels during isolation and were extensively delipidated, exhibited full biophysical activity only at higher protein concentrations and with prolonged pulsation. Extensively delipidated samples of SP-BC obtained by method (c) exhibited impaired biophysical activities, even when prepared with neutral organic solvents. Reconstituted surfactant samples containing SP-C (3.5 kDa) obtained by any of the methods listed above were only able to reduce the surface tension at minimum bubble radius to approx. 20 mN/m. The biophysical activity of SP-C (3.5 kDa) was not significantly affected by low pH or extensive delipidation. Reconstituted samples containing mixtures of SP-BC (15 kDa: nonreduced) and SP-C (3.5 kDa) were more effective than samples containing either protein alone. Furthermore, with samples containing both hydrophobic proteins the final surface tensions at maximum bubble radius were attained within a few bubble pulsations.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Gene transactivation mediated by the TAT gene of human immunodeficiency virus in transgenic mice.

Transgenic mice were generated carrying either the long terminal repeat of Human Immunodeficiency Virus fused to the bacterial chloramphenicol acetyl transferase reporter gene or a control element of the murine alpha A crystallin gene fused to the tat gene of human immunodeficiency virus. By crossing these two strains, progeny were obtained which carried both transgenes. The bacterial reporter gene was specifically transactivated in the eyes of these animals.

Acetyltransferases↗
PubMed1988

A renal biopsy study of hepatitis B virus-associated nephropathy in Korea.

The pathogenic role of the hepatitis B virus (HBV) infection for glomerulonephritis (GN) is not clear. The frequency of HBsAg has been studied in sera of 732 consecutive patients who have glomerular diseases by using radioimmunoassay. The frequency of HBs antigenemia was 11.9%, which was not different from that in the general population of South Korea. Of the 87 HBsAg seropositive patients with GN, 29 cases with membranoproliferative GN (MPGN) and eighteen with membranous nephropathy (MN) were diagnosed as having HBV-associated nephropathy. Eighty-seven and one-half percent of the adults with MPGN and 80% of the children with MN were HBsAg carries. The morphologic findings and laboratory data in cases with HBV-associated MPGN and MN did not differ significantly from those observed in patients with MPGN and MN without circulating HBsAg. Yet mesangial deposits were more frequently noted in patients with HBV-associated MN when compared to others with idiopathic MN. Glomerular deposits of HBsAg were not detected using indirect immunofluorescence technique. Even though HBsAg was not demonstrable within the glomeruli, HBV infection seems to play an important role in the pathogenesis of MPGN in Korean adults and MN in children.

Adolescent↗
PubMed1988

Effect of reconstituted pulmonary surfactant containing the 6000-dalton hydrophobic protein on lung compliance of prematurely delivered rabbit fetuses.

Chloroform:methanol extracts of bovine pulmonary surfactant contain small hydrophobic proteins, designated surfactant-associated apoproteins 6,000 (SAP-6), but do not contain the major surfactant-associated 35,000-dalton glycoprotein, designated SAP-35. Examination of lipid extract surfactant on sodium dodecylsulfate-polyacrylamide gel electrophoresis revealed hydrophobic proteins with apparent molecular masses of 15,000, 7,000, and 3,5000 daltons prior to reduction. After reduction, the 15,000-dalton species largely disappeared and was replaced by a 5,000-dalton species. In addition, the 7000- and 3500-dalton species exhibited a slightly enhanced mobility. Amino acid analysis demonstrated that SAP-6 possesses a more highly hydrophobic profile than SAP-35. Combining the protein-containing fractions from silicic acid chromatography of lipid extract with synthetic dipalmitoylphosphatidylcholine produced a reconstituted surfactant preparation which was just as active as lipid extract surfactant on a pulsating bubble surfactometer. The reconstituted surfactant contained SAP-6 but not SAP-35. Pressure-volume studies revealed that, at the optimal dose, reconstituted surfactant containing half the SAP-6 concentration of lipid extract exhibited similar effectiveness to lipid extract surfactant in promoting lung expansion with prematurely delivered rabbit fetuses of 27 days gestation. Reconstituted surfactant with an identical SAP-6 protein concentration as lipid extract possessed the same biological properties as the preparation with 1% SAP-6 protein. These studies support the view that an artificial surfactant composed of synthetic or semisynthetic lipids plus human SAP-6 produced via biotechnology could be useful for prevention and/or treatment of the neonatal respiratory distress syndrome.

Animals↗
PubMed1987

Protein sequence analysis studies on the low molecular weight hydrophobic proteins associated with bovine pulmonary surfactant.

Lipid extracts of bovine pulmonary surfactant, which exhibit biophysical and biological activity, contain two hydrophobic proteins which have been designated surfactant protein-B (SP-B) and SP-C. Amino terminal amino acid sequence analysis of whole lipid extracts and partially purified protein fractions gave rise to three sequences, two major and one minor. The first sequence, identified as a member of the SP-B family, extended for 60 amino acids beginning with an amino terminal phe. The second polypeptide, identified as a member of the SP-C family, sequenced for 35 amino acids and had a leu amino terminus. The third minor sequence corresponded to amino acids 2-9 of SP-C (N-leu) and was designated SP-C (N-ile). Sequence analysis of cyanogen bromide peptides derived from methyl isocyanate-blocked lipid extract material produced two peptides which extended the amino acid sequence of SP-B to residue 79, which appears to be a glycine.

Amino Acid Sequence↗
PubMed1987

Characterization of the small hydrophobic proteins associated with pulmonary surfactant.

Lipid extracts of bovine pulmonary surfactant, which retain many of the biophysical characteristics of natural surfactant, contain approx. 98% lipid and 2% protein, as determined by amino acid analysis. Polyacrylamide/urea gel electrophoresis reveals that lipid extract surfactant contained a major apoprotein band with apparent Mr 3500 and minor apoprotein bands with apparent Mr 15,000 and 7000. After reduction, the 15 kDa band disappears and is replaced by a prominent band with apparent Mr = 5000. Reduction also results in a relative diminution of the 7 kDa band and a relative increase in the intensity of the 3.5-kDa band. Edman degradation reveals two major peptide sequences which have been designated surfactant-associated peptide (N-terminal Phe) and surfactant-associated peptide (N-terminal Leu) and a minor sequence designated surfactant-associated peptide (N-terminal Ile). The latter surfactant-associated peptide appears to be related to the N-terminal Leu peptide but lacks the terminal Leu. N-Terminal analysis by dansylation demonstrates that the 15 and 5 kDa (reduced) apoprotein species contain N-terminal Phe, Leu and Ile. The 3.5 and 7 kDa bands contain only N-terminal Leu and Ile. Chromatography of lipid extracts on silicic acid columns gives rise to fraction I, which contains protein and phosphatidylglycerol, and fraction II, which contains protein, phosphatidylglycerol and phosphatidylethanolamine. Fraction I was primarily composed of the 15-kDa apoproteins, while fraction II contained mainly the 3.5 and 7 kDa apoproteins. Both fractions exhibited biophysical activity after reconstitution with dipalmitoylphosphatidylcholine. These results indicate that lipid extracts contain an oligomer of 15 kDa containing surfactant-associated peptide (N-terminal Phe) and surfactant-associated peptides (N-terminal Leu or Ile) which interact through sulfhydryl and perhaps other bonds. Lipid extracts also contain 3.5 kDa monomers of surfactant-associated peptides with N-terminal Leu and N-terminal Ile which can dimerize through sulfhydryl and perhaps hydrophobic interactions.

Amino Acid Sequence↗
PubMed1986

Reconstitution of surfactant activity by using the 6 kDa apoprotein associated with pulmonary surfactant.

Lipid extracts of bovine pulmonary surfactant containing the 6 kDa apoprotein, but lacking the 35 kDa apoprotein, can mimic the essential characteristics of pulmonary surfactant on a pulsating-bubble surfactometer. Reconstituted surfactant can be produced by combining silicic acid fractions containing 6 kDa apoprotein and phosphatidylglycerol with phosphatidylcholine. Treatment of the protein-containing fraction with proteolytic enzymes abolishes its efficacy. These results indicate that the presence of the 6 kDa apoprotein can account for some of the essential physical and biological characteristics of pulmonary surfactant. Immunodiffusion studies indicate that, contrary to earlier suggestions, the 6 kDa apoprotein is not structurally related to the major surfactant apoprotein that has a molecular mass of 35 kDa.

Animals↗
PubMed1986

Malignant hypertension: aetiology and outcome in 83 patients.

To evaluate the current pattern of aetiology and outcome in malignant hypertension, we reviewed all medical records of patients presenting between 1979 and 1985 who fulfilled WHO criteria for malignant hypertension. There were 83 patients, 43 males (52%) and 40 females (48%). Primary malignant hypertension was diagnosed in 17 cases (20%) and secondary lesions in 66 cases (80%). Overall one year survival was 94%, and 5 year survival 75%, which is similar to recent reports. Initial serum creatinine was a prognostic indicator.

Adolescent↗