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Biomedical subjects

S Q Li

Publications and source records attributed to S Q Li.

At least 19 recordsLinked to original sources
PubMed1992

Influenza A virus transfectants with chimeric hemagglutinins containing epitopes from different subtypes.

Influenza virus transfectants with chimeric hemagglutinins were constructed by using a ribonucleoprotein transfection method. Transfectants W(H1)-H2 and W(H1)-H3 contained A/WSN/33(H1N1) (WSN) hemagglutinins in which the six-amino-acid loop (contained in antigenic site B) was replaced by the corresponding structures of influenza viruses A/Japan/57(H2N2) and A/Hong Kong/8/68(H3N2) (HK), respectively. Serological analysis indicated that the W(H1)-H3 transfectant virus reacted with antibodies against both the WSN and HK viruses in hemagglutination inhibition and plaque neutralization assays. Furthermore, mice immunized with W(H1)-H3 transfectant virus produced antibodies to the WSN and HK viruses. The results demonstrate that influenza virus transfectants can be engineered to express epitopes of different subtypes on their hemagglutinins.

Amino Acid Sequence↗
PubMed1992

[Mutual influence of aminophyllin and cefotaxime in the treatment of pulmonary heart disease].

The serum Aminophyllin (TP) and Cefotaxime (CTX) concentration of the patients of pulmonary heart disease during alute attack were measured by HLPC at 2 h and 6 h after infusion. (1) TP and CTX alone were used (2) TP and CTX were used simultaneously. The result showed that the concentrations of TP were much higher, but CTX were much lower when use CTX and TP simultaneously, at 2 h and 6 h (P < 0.01, P < 0.05). The concentration of TP of pulmonary heart disease with heart failure was higher than without heart failure at 6 h when alone were used or simultaneous were used (P < 0.01), CTX wasn't correlated with heart failure. The concentrations of TP and CTX did not correlate with PaO2 and PaCO2. It showed that TP and CTX would not be used simultaneously.

Aminophylline↗
PubMed1992

[A study on the relationship between maximal titers of anti-HBs antibodies and persistence of protective level after vaccination].

300 recipients with negative for HBsAg anti-HBs, anti-HBc were vaccinated by 3 kinds of hepatitis B vaccine at 0, 1, 6 months. 266 students with maximal titers of anti-HBs detected after the 3rd immunization were divided into 4 groups: 10-100, 101-500, 501-1,000, > 1000 mlU/ml. A study on the relationship between maximal titers of anti-HBs and the protective time was carried out. The results showed that in the 1st group the titers of anti-HBs of 52.6%, 84.2% and 94.7% recipients decreased to or below 10 mIU/ml when detected one, two and three years after vaccination respectively; the titers of 5.2%, 31% and 56.9% decreased to or below 10 mIU/ml when detected. 1, 2 and 3 years after vaccination respectively in the 2nd group, while the titers of only 0.7% recipients decreased to or below 10 mIU/ml when detected 3 years after vaccination in the 1st group. The decreasing rate of titers of Anti-HBs was similar in 4 groups. The titers of anti-HBs were 90% reduction after 1st immunization in the first 24 months. Then the decreasing rate became slower. Therefore, we suggested that peoples should be revaccinated according to their maximal titers of anti-HBs after completed course of vaccination.

Adolescent↗
PubMed1991

Determination of the Mark-Houwink equation for chitosans with different degrees of deacetylation.

The values of k and alpha in the Mark-Houwink equation have been determined for chitosans with different degrees of deacetylation (DD) (69, 84, 91 and 100% respectively), in 0.2 M CH3COOH/0.1 M CH3COONa aqueous solution at 30 degrees C by the light scattering method. It was shown that the values of alpha decreased from 1.12 to 0.81 and the values of k increased from 0.104 x 10(-3) to 16.80 x 10(-3) ml/g, when the DD varied from 69 to 100%. This is due to a reduction of rigidity of the molecular chain and an increase of the electrostatic repulsion force of the ionic groups along the polyelectrolyte chain in chitosan solution, when the DD of chitosan increases gradually.

Acetylation↗
PubMed1991

The no-scalpel vasectomy.

A refined method of delivering the vas deferens for vasectomy has been developed and used in China since 1974. This method eliminates the scalpel, results in fewer hematomas and infections, and leaves a smaller wound than conventional techniques. An extracutaneous fixation ring clamp encircles and firmly secures the vas without penetrating the skin. A sharp curved hemostat punctures and dilates the scrotal skin and vas sheath. The vas is delivered, cleaned and occluded by the surgeon's preferred technique. The contralateral vas is delivered through the same opening. The puncture wound contracts to about 2 mm., is not visible to the man and requires no sutures for closure. The reported incidence of hematoma in 179,741 men followed in China was 0.09%. No hematomas or infections were identified in the first 273 procedures performed by a surgeon in the United States. The operating time in China and for the last 50 United States procedures has ranged from 5 to 11 minutes. The disadvantage of the technique is the hand-on training and number of cases necessary to gain proficiency. However, the advantages for surgeons and patients should enhance the popularity of vasectomy.

Anesthesia, Local↗
PubMed1991

An in vitro assessment of human fetal pancreatic islets of Langerhans in culture.

The human fetal pancreas is a potential source of islets for transplantation into insulin-dependent diabetic patients. In this study, 35 human fetal pancreas obtained from prostaglandin-induced abortions (12-26 weeks gestation), were placed in culture to determine their capacity to secrete insulin over 30 days. Culture media were sampled twice weekly for insulin and histology was performed serially. Of the 35 pancreases cultured, six were lost due to bacterial contamination, five discarded due to undetectable levels of insulin in culture, nine are still under study, whilst 15 pancreases have been cultured for one month, and insulin studies completed. Three patterns of insulin release were observed: (a) progressive decline (n = 6), indicating non-viable tissue at the onset; (b) delayed decline, indicating significant tissue damage before organ culture (n = 5); and (c) insulin production in vitro over 30 days (n = 4), with viable islets detected histologically. Factors such as gestational age and cold ischaemia time did not correlate with the pattern of insulin secretion observed. This was probably due to a more important variable, not easily assessed, of the period of intrauterine (warm) ischemia. These data suggest: (1) that a small number of fetal pancreases procured from prostaglandin-induced abortuses do yield islets which remain viable in culture over 30 days, and (2) the functional status of islets can be monitored in vivo by measuring insulin secretion, thereby providing a means of identifying tissue suitable for transplantation.

Culture Techniques↗
PubMed1991

Fetal pig pancreas--a preliminary assessment of tissue for transplantation.

Porcine fetal pancreases (PFP) obtained from 4 pregnant sows were pooled, minced into 1 mm3 fragments and studied in organ culture for up to 30 days to determine tissue viability and insulin production in vitro. After 7-9 days in culture, some of these explants were transplanted into euglycemic, N:NIH-nu(s) nude recipient mice, and studied histologically over 69 days following grafting. Using RPMI 1640 supplemented with 5% fetal calf serum as the culture medium in 90% air/10% CO2, it was found that explants were viable with insulin production detected in vitro, which was maximal at day 7 (197 +/- 18.9 mU/L, n = 11), and gradually declined thereafter. By 22 days, insulin levels were less than 60.1 +/- 28.5 mU/L (n = 6). Histology of the explants showed viable tissue with evidence of mitoses present in insulin-positive cells at day 16 in vitro. Beyond this time, tissue viability diminished. Explants transplanted into euglycemic nude mice did not undergo rejection during the observation period of 69 days. Grafts remained viable with evidence of an increase in mitotic activity in the endocrine tissue on immunoperoxidase staining. These preliminary investigations confirm that pancreatic explants from porcine fetuses can be maintained in culture for up to 16 days. Such explants, when transplanted under the kidney capsule of euglycemic, nude mice, did not undergo necrosis, but remained viable, with evidence of mitoses in the islet tissue.

Animals↗
PubMed1991

Accessory heart graft as a surgical model in studies of transplantation immunology.

The heterotopic heart graft was examined as a surgical model for in vivo studies of transplantation immunology. Two innovations previously described distinguish it from an orthotopic heart transplant; its heterotopic, superficial position in the neck, and the use of portex cuffs to facilitate anastomoses of donor aorta and pulmonary artery to recipient common carotid artery and external jugular vein respectively. In this study, few modifications to the original technique were required. However, to ensure a high technical success rate exceeding 95%, it was found that the use of small donors (less than 200 g) and large recipient rats (greater than 230 g) was required. The former minimised the risk of kinking of the venous anastomoses, and the latter ensured an adequate luminal diameter of the carotid artery to facilitate the cuff anastomosis. With the vena cava and pulmonary veins ligated, the transplant served purely as an indicator graft with rhythmic contractions discernible by inspection or palpation. This simplified monitoring of the graft, with no requirement for ECG or biochemical studies. The direction of blood flow was established by angiography as via the aorta to the coronary vessels, returned to the right atrium and ventricle and out through the pulmonary artery to the recipient circulation. As the accessory heart did not provide any life-sustaining function, it could be removed for histological studies once rejection had occurred without compromising the survival of the recipient animal. This allowed the use of the recipient for further studies on its immunological status, including the performance of second grafts.

Animals↗
PubMed1991

Induction of tolerance to vascularised skin allografts using cyclosporin A--an experimental study on rats.

This study investigates the induction of tolerance to vascularised skin allografts in a low responder rodent strain combination. Pedicle skin grafts based on the epigastric vessels were grafted between Dark Agouti (DA) and Piebald Virol Glaxo (PVG) rats (n = 24). An extended treatment protocol of high dose cyclosporin A (CyA) (25 mg/kg) spanning nine weeks was used. The mean survival time of epigastric skin grafts in the no treatment control group was 7.6 days (n = 10). With high dose CyA (25 mg/kg), 5/14 animals died during CyA treatment with intact skin grafts. The remaining nine animals enjoyed prolonged graft survival throughout the treatment period. Between one and four weeks following cessation of CyA, rejection occurred in six of nine animals which could not be reversed by pulse CyA treatment. Long term graft survival greater than 200 days was achieved in three animals, but two animals went on to reject their grafts at 231 and 238 days post transplant. Only one animal became tolerant, as confirmed by the retention of a fresh donor-specific free skin graft, without the need for further CyA. This study confirms the difficulty of tolerance induction to vascularised skin grafts, despite using a dose schedule of CyA far in excess of that required to achieve tolerance to other solid organ grafts such as hearts.

Animals↗
PubMed1991

A study of the xenogeneic response in an isolated liver perfusion circuit--preliminary observations.

An isolated liver perfusion circuit was developed to study the xenogeneic reaction of human blood to porcine liver, and investigate the feasibility of using such a system for liver dialysis in fulminant hepatic failure. Three experimental groups were studied: a control group where pooled porcine blood was perfused through pig liver (n = 12), a xenogeneic group where banked human blood was perfused through porcine liver (n = 23), and a modified xenogeneic group where decomplemented human blood was perfused through porcine liver (n = 4). The following parameters of liver function were assessed: liver function tests, serum electrolytes, bile and ascites production. In addition, liver histology was assessed at the start and completion of each perfusion experiment. Control experiments established that the use of low perfusion pressures (mean inlet pressure of 29.5 +/- 7.4 mmHg), and low haematocrit of 20.5 +/- 8.9% (n = 14), enabled five hour perfusions to be consistently achieved with maintenance of normal acid base and electrolyte balance. Bile production over 5 hours was 18.8 +/- 8.0 ml in controls (n = 5) and 17.0 +/- 6.7 ml in the xenogeneic (human-pig) circuit (n = 11) (NS). Ascites production was 235.8 +/- 157.3 ml/hr in controls (n = 5) and 205 +/- 142.0 ml/hr in the xenogeneic circuit (n = 7) (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗