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Biomedical subjects

S S Lin

Publications and source records attributed to S S Lin.

At least 73 records · Page 4Linked to original sources
PubMed1998

Soft and hard tissue changes in Class III patients treated by bimaxillary surgery.

A cephalometric study of 17 non-growing dentate Class III subjects treated by bimaxillary surgery was undertaken to assess the results of treatment and to evaluate the correlation between soft and hard tissue change. It was concluded that: (i) the orthognathic profiles achieved were brought about by a combination of maxillary advancement and mandibular setback; (ii) a strong correlation in the horizontal direction occurred between all the selected landmarks of the lower lip and chin, but only between superior labial sulcus and point A in the upper lip; highest intra-group correlations were seen between corresponding soft and hard tissue points; the ratios of soft tissue to corresponding hard tissue movements in lower lip and chin approached 1:1; (iii) in the vertical direction, a strong correlation occurred in the lower lip and chin; highest intra-group correlations were not necessarily with corresponding landmarks; and (iv) vertical movement of landmarks on the nasal base and upper lip generally showed poor or weak correlation with corresponding soft tissue points. The most reliable hard tissue predictors of horizontal and vertical soft tissue change are tabulated for application in bimaxillary surgery for the Class III patient.

Adult↗
PubMed1998

Differential recognition by proteins of alpha-galactosyl residues on endothelial cell surfaces.

The binding of proteins to cell surface carbohydrates contributes to cell-cell interactions in development, immunity, and various physiologic processes. Such interactions are presumably dictated not only by the chemical structure of the carbohydrate but also reflect the properties of the protein and the microenvironment in which the protein-carbohydrate interaction occurs. To explore the factors influencing the recognition of cell surface carbohydrates by proteins, the extent to which three classes of proteins--anti-Gal alpha 1-3Gal IgM found in higher primates, Griffonia simplicifolia type I lectin, isolectin B4 (GS-IB4), and alpha-galactosidase--interact with Gal alpha 1-3Gal on porcine cell surfaces was tested. Although the Gal alpha 1-3Gal residues expressed on porcine endothelial cells and recognized by anti-Gal alpha 1-3Gal IgM and GS-IB4 were both sensitive to cleavage by alpha-galactosidase, the sites recognized by GS-IB4 were more sensitive to cleavage than sites recognized by anti-Gal alpha 1-3Gal IgM. Cross-blocking studies on porcine cell surfaces revealed that a significant proportion of anti-Gal alpha 1-3Gal IgM bound to sites not recognized by GS-IB4; however, anti-Gal alpha 1-3Gal IgM and GS-IB4 recognized the same sites on solubilized membrane proteins and model compounds. These results suggest that features of the cell surface such as the three-dimensional arrangement of Gal alpha 1-3Gal and characteristics of the protein such as size and valency play critical roles in specific interactions on cell surfaces.

Animals↗
PubMed1998

Bone healing of tibial lengthening is enhanced by hyperbaric oxygen therapy: a study of bone mineral density and torsional strength on rabbits.

We investigated the effect of intermittent hyperbaric oxygen (HBO) therapy on the bone healing of tibial lengthening in rabbits. Twelve male rabbits were divided into two groups of six animals each. The first group went through 2.5 atmospheres absolute of hyperbaric oxygenation for 2 hours daily, and the second group did not go through hyperbaric oxygenation. Each animal's right tibia was lengthened 5 mm using an uniplanar lengthening device. Bone mineral density (BMD) study was performed for all of the animals at 1 day before operation and at 3, 4, 5, and 6 weeks after operation. All of the animals were killed at 6 weeks postoperatively for biomechanical testing. Using the preoperative BMD as an internal control, we found that the BMD of the HBO group was increased significantly compared with the non HBO group. The mean %BMD at 3, 4, 5, and 6 weeks were 69.5%, 80.1%, 87.8%, and 96.9%, respectively, in HBO group, whereas the mean %BMD were 51.6%, 67.7%, 70.5%, and 79.2%, respectively, in non-HBO group (two tailed t test, p < 0.01, p < 0.01, p < 0.01, and p < 0.01 at 3, 4, 5, and 6 weeks, respectively). Using the contralateral nonoperated tibia as an internal control, we found that torsional strength of lengthened tibia of the HBO group was increased significantly compared with the non-HBO group. The mean percent of maximal torque was 88.6% in HBO group at 6 weeks, whereas the mean percent of maximal torque was 76.0% in non-HBO group (two-tailed t test, p < 0.01). The results of this study suggest that the bone healing of tibial lengthening is enhanced by intermittent hyperbaric oxygen therapy.

Absorptiometry, Photon↗
PubMed1997

Solid phase synthesis and restriction endonuclease cleavage of oligodeoxynucleotides containing 5-(hydroxymethyl)-cytosine.

Emerging data suggest an important role for cytosine methylation in tumorigenesis. Simultaneously, recent studies indicate a significant contribution of endogenous oxidative DNA damage to the development of human disease. Oxidation of the 5-methyl group of 5-methylcytosine (5mC) residues in DNA results in the formation of 5-(hydroxymethyl)cytosine (hmC). The biological consequences ofhmC residues in vertebrate DNA are as yet unknown; however, conversion of the hydrophobic methyl group to the hydrophilic hydroxymethyl group may substantially alter the interaction of sequence-specific binding proteins with DNA. Central to both biophysical and biochemical studies on the potential consequences of specific DNA damage products such as hmC are efficient methods for the synthesis of oligodeoxynucleotides containing such modified bases at selected positions. In this paper, we describe a method for the placement of hmC residues in oligodeoxynucleotides using established phosphoramidite chemistry. In addition, we have examined the influence of specific hmC residues on enzymatic cleavage of oligodeoxynucleotides by the methylation-sensitive restriction endonucleases MspI and HpaII.

5-Methylcytosine↗
PubMed1997

Humoral responses to pig-to-baboon cardiac transplantation: implications for the pathogenesis and treatment of acute vascular rejection and for accommodation.

Organs transplanted between phylogenetically-disparate species, such as from the pig into the primate, are subject to hyperacute and acute vascular rejection. Hyperacute rejection of a porcine organ by a primate is thought to be initiated by the binding of xenoreactive natural antibodies to Galalpha1-3Gal expressed on the endothelial lining of blood vessels in the xenograft. The factor(s) which initiates acute vascular rejection is uncertain; however, there is some evidence implicating xenoreactive antibodies. The nature of the humoral response which might contribute to acute vascular rejection of a porcine organ was investigated in baboons which received a porcine cardiac xenograft plus immunosuppression with methylprednisolone, azathioprine, and cyclosporine. Following rejection and surgical removal of the xenografts, the serum concentration of xenoreactive antibodies increased in untreated animals but in immunosuppressed animals was similar to the concentration in preimmune serum. The antibodies in the sensitized recipients were specific for Galalpha1-3Gal (70-95%) and other determinants (5-30%). However, cross-blocking studies showed that, following xenotransplantation, the immunosuppressed baboons had no detectable IgM or IgG directed against "new" endothelial antigens. These results indicate that antibodies made by immunosuppressed individuals in response to xenotransplantation are much like xenoreactive natural antibodies and suggest that acute vascular rejection might in some cases be addressed by therapeutic strategies aimed at those antibodies.

Animals↗
PubMed1997

The role of natural anti-Gal alpha 1-3Gal antibodies in hyperacute rejection of pig-to-baboon cardiac xenotransplants.

Xenoreactive natural antibodies in humans and higher primates are directed predominantly at Gal alpha 1-3Gal. These antibodies are thought to initiate hyperacute rejection of porcine organ xenografts. The contribution of anti-Gal alpha 1-3Gal antibodies to the xenoractive natural antibody repertoire and to the initiation of hyperacute rejection was tested in a pig-to-baboon cardiac xenograft model. Anti-Gal alpha 1-3Gal antibodies were depleted from baboons by extracorporeal absorption of anti-Gal alpha 1-3Gal antibodies from plasma using columns with a matrix bearing Gal alpha 1-3Galb1-4GlcNAc. Specific removal of anti-Gal alpha 1-3Gal antibodies was achieved prior to transplantation as demonstrated by immunoassay. Porcine hearts were then transplanted into these baboons and the outcome of the transplants was analysed. Immunofluorescence revealed little deposition of baboon antibodies in the grafts. The porcine hearts did not undergo hyperacute rejection even though complement activity was approximately 90% of baseline at the time of transplantation. These findings demonstrate that anti-Gal alpha 1-3Gal antibodies constitute a major fraction of xenoreactive natural antibodies in primate blood and that these antibodies contribute significantly to the pathogenesis of hyperacute xenograft rejection.

Acute Disease↗
PubMed1997

Effect of intermittent cigarette smoke inhalation on tibial lengthening: experimental study on rabbits.

We investigated the effect of intermittent cigarette smoke inhalation on the bone healing of tibial lengthening in rabbits. Thirty-eight male rabbits were divided into two groups of 19 animals each. The first group went through intermittent cigarette smoke inhalation, and the second group did not go through intermittent cigarette smoke inhalation. Each animal's right tibia was lengthened 5 mm using an uniplanar lengthening device. Five animals of each group were killed at 4, 6, and 8 weeks postoperatively for biomechanical testing, and one animal of each group was killed at 2, 4, 6, and 8 weeks postoperatively for histologic study. Using the contralateral nonoperated tibia as an internal control, we found that torsional strength of the lengthened tibia of the smoke inhalation group was decreased significantly compared with the non-smoke inhalation group. The mean percent of maximal torque at 4, 6, and 8 weeks were 22.0, 66.3, and 78.6%, respectively, in the smoke inhalation group, whereas the mean percent of maximal torque were 48.0, 84.1, and 90.8% %, respectively, in non-smoke inhalation group (one-tailed t test, p < 0.01, p < 0.01, and p < 0.05 at 4, 6, and 8 weeks, respectively). Our histologic observations revealed that the granulation tissue resorption, bone formation, and remodeling were delayed in smoke inhalation group. The results of this study suggest that intermittent inhalation of cigarette smoke delays, but does not prevent, the bone healing in tibial lengthening.

Animals↗
PubMed1997

[HPLC determination of five caffeine metabolites].

An HPLC method for the determination of caffeine metabolites in urine was established. Shim Pack CLC-ODS column (5 microns) was eluted with the mobile phase of methanol--acetonitrile--0.05% acetic acid = 12:1:87 (v/v) at a flow rate of 1.2 ml.min-1, and the ultraviolet absorbance was monitored at 280 nm. The 13 caffeine metabolites and caffeine were well separated and the concentrations of the five metabolites, AFMU, 1U, 1X, 17U, and 17X, were determined. The recoveries of the five metabolites were above 87%, the inter- and intra-day variations were less than 3%. The concentrations of the five metabolites in 120 volunteers were determined. The ratios of the metabolites were employed for the assessment of CYP1A2, NAT, and XO enzymes successfully.

Caffeine↗
PubMed1997

Sterol regulation of acetyl coenzyme A carboxylase promoter requires two interdependent binding sites for sterol regulatory element binding proteins.

The sterol regulatory element binding proteins (SREBPs) are central regulators of lipid homeostasis in mammalian cells. Their activity is controlled by a sterol-regulated two-step proteolytic process that releases the nuclear targeted amino-terminal domain from the membrane anchored carboxyl-terminal remnant. This ensures that transcriptional stimulation of the appropriate genes occurs only when increased intracellular sterol accumulation is required. Gene targets for SREBP encode key proteins of cholesterol metabolism as well as essential proteins of fatty acid biosynthesis, providing a mechanism for coordinate control of these two major lipid pathways when sterols and fatty acids need to accumulate together. However, the regulatory mechanism must provide a way to uncouple these two pathways to allow separate regulation when sterol or fat levels need to increase independently of each other. We compared the similarities and differences for how SREBP activates the promoter for the low density lipoprotein (LDL) receptor, which is the key protein involved in cholesterol uptake, relative to how it activates promoters for acetyl coenzyme A carboxylase (ACC) and fatty acid synthase (FAS), which are both key enzymes of fatty acid biosynthesis. In the current studies we show there are two distinct sites for SREBP binding that control activation of the ACC PII promoter whereas previous work has shown there is only a single SREBP site in the LDL receptor. Additionally, disruption of either ACC site results in a total loss in promoter function and a severe decrease in SREBP binding even to the neighboring unaltered site. Thus, the two sites are equally important and dependent on one another for optimal function. This is in contrast to the FAS promoter where SREBP binds to two adjacent sites independently and the one located closer to the binding site for the Sp1 co-regulator is more critical for sterol regulation and activation by SREBP over-expression.

Acetyl-CoA Carboxylase↗
PubMed1997

Comparison of intravenous retention of fentanyl and lidocaine on local analgesia in propofol injection pain.

BACKGROUND: With a tourniquet on arm for arresting venous blood flow, we evaluated the efficacy of intravenous (i.v.) retention of fentanyl and lidocaine in reducing the pain on i.v. propofol injection during general anesthesia. METHODS: One hundred and twelve patients were studied. Following a venous occlusion by a tourniquet inflated to 70 mmHg, patients in Group A (n = 38) received normal saline (NS) 3 ml, while those in Group B (n = 37) and in Group C (n = 37) respectively received fentanyl 150 micrograms or 3 ml and 2% lidocaine 3 ml (60 mg). The venous retention of drug was maintained for 1 min, followed immediately by tourniquet release and propofol 100 mg i.v. injection over 20 s. RESULTS: Both fentanyl and lidocaine treatments (Groups B and C) were significantly better than placebo (Group A) in reducing pain on propofol injection (p < 0.005). Lidocaine 60 mg was more effective than fentanyl 150 micrograms in reduction of pain associated with i.v. propofol (p < 0.001). Injection of fentanyl itself caused pain in 28% of patients as compared to 2% in the lidocaine group. Mild local skin erythema was noted in 14% of patients with fentanyl venous retention versus 0% of patients with lidocaine venous retention. CONCLUSIONS: Intravenous retention of fentanyl 150 micrograms, although less effective than that of lidocaine (p < 0.001), showed local analgesic effect in reducing the pain on propofol injection. The hypothetic mechanisms of action were speculated.

Adolescent↗
PubMed1996

Transplantation of discordant xenografts: a challenge revisited.

Six years ago, Jeffrey Platt and colleagues reviewed the biological hurdles to transplanting organs between species. The ensuing years have allowed the concepts advanced at that time to be tested leading to significant progress in understanding the immunology of xenotransplantation and in developing strategies for potential clinical application. Here, William Parker and colleagues review that progress.

Animals↗
PubMed1996

Plantar forefoot ulceration with equinus deformity of the ankle in diabetic patients: the effect of tendo-Achilles lengthening and total contact casting.

Between 1993 and 1995, 93 neuropathic diabetes mellitus patients with foot ulcers underwent a total contact cast (TCC) protocol. A randomly chosen group of 21 patients (Group I) demonstrated ulcer healing in a mean time of 43.5 days. Despite 9 weeks of TCC, 15 patients (Group II) with forefoot ulcers failed to heal. Physical examination of Group I revealed plantarflexion/dorsiflexion range of motion of the ankle of 33.8 degrees / 1.9 degrees compared to 32.3 degrees / -10.5 degrees of Group II, demonstrating an ankle equinus deformity and limited joint motion. Group II patients underwent a correction of the equinus deformity with percutaneous tendo-Achilles lengthening (TAL), followed by a TCC. All but one ulcer (93.3%) healed within 39.4 days. Four (19.0%) ulcers recurred (at the same site) in Group I, compared to none in Group II at the latest follow up of 17.3 months. Surgical correction with percutaneous TAL and TCC results in healing of forefoot ulcer and helps prevent ulcer recurrence.

Achilles Tendon↗
PubMed1996

[Comparison of immunoassay kits for detection of staphylococcal enterotoxins produced by Staphylococcus aureus].

UNLABELLED: Four commercial kits, SET-RPLA, RIDASCREEN, SET-EIA, and TECRA, were compared for the efficiency of detecting staphylococcal enterotoxins (SE). There was no non-specific reaction for detection of SE produced by 21 Staphylococcus aureus strains from 5 outbreaks of food poisoning using SET-RPLA, SET-EIA and TECRA kits. The background of the results of RIDASCREEN kit was high and non-specific reactions were present in some strains. IN CONCLUSION: (i) TECRA kit is suggested to be used for screening SE producing strains; (ii) SET-RPLA and RIDASCREEN kits are suitable for epidemiological investigation of SE types, but the lack of ability for detecting SEE, long time required for testing with SET-RPLA kit and high background when using RIDASCREEN kit must be overcome; and (iii) because of the complicated test procedures and the lack of ability for detecting SEE, the practicality of SET-EIA kit in screening and epidemiological research purposes is low.

Enterotoxins↗
PubMed1996

[Serotype distribution and antimicrobial susceptibility of group A streptococci (Streptococcus pyogenes) isolated in Taiwan].

T-protein serotypes and antimicrobial susceptibility of a total of 139 group A streptococci (GAS) strains isolated in Taiwan area in 1993 and during the outbreak of scarlet fever in 1994 were analyzed. All strains were T-typable, and T12 (42.46%) and T4 (38.85%) were the dominant T types. According to the results of analysis of antimicrobial susceptibility, all GAS strains were divided into 9 resistotypes, A (all susceptible), B (resistant to tetracycline), C (resistant to erythromycin and tetracycline), D (resistant to chloramphenicol and tetracycline), E (resistant to chloramphenicol and clindamycin), F (resistant to chloramphenicol, clindamycin and tetracycline), G (resistant to clindamycin, erythromycin and tetracycline), H (resistant to chloramphenicol, clindamycin, erythromycin and tetracycline), and I (resistant to chloramphenicol, clindamycin, erythromycin, tetracycline and vancomycin). Type B (37.42%) was the dominant type. Type A (25.91%), and type H (26.63%) also appered with high incidence. Most of strains isolated from Mid-Taiwan were type H. Only one strain, that was isolated in I-lan, was resistant to vancomycin, in addition to resistant to chloramphenicol, clindamycin, erythromycin, and tetracycline. All strains were susceptible to penicillin G, ampicillin, and ceftriaxone. Some strains were resistant to chloramphenicol (32.38%), clindamycin (30.22%), erythromycin (31.66%), tetracycline (73.39%), and vancomycin (0.70%). During the outbreak of scarlet fever in 1994, the dominant T types of strains isolated in North-Taiwan and Mid-Taiwan were T4 and T12, respectively, and the major resistotypes of those strains were B and H types, respectively. These clues suggested that the outbreaks occurring in North-Taiwan and Mid-Taiwan may have no epidemiological linkage between each other.

Disease Outbreaks↗