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Biomedical subjects

P K Lee

Publications and source records attributed to P K Lee.

At least 19 recordsLinked to original sources
PubMed1992

Nucleotide sequences and biologic properties of toxic shock syndrome toxin 1 from ovine- and bovine-associated Staphylococcus aureus.

Toxic shock syndrome toxin (TSST) 1 was purified from ovine (TSST-ovine) and bovine (TSST-bovine) mastitis-associated Staphylococcus aureus. These toxins were previously reported to have molecular weights identical to that of human TSST-1. However, TSST-ovine was reported as having an isoelectric point (pI) of 8.5, whereas TSST-bovine has the same pI (7.2) as TSST-1. Nucleotide sequence analysis revealed that TSST-bovine was identical to TSST-1 and that TSST-ovine had 14 nucleotide differences that changed 9 amino acid residues. Only 1 nucleotide difference, at position 514, was predicted to cause an amino acid charge difference, as glutamic acid at position 132 of TSST-1 was changed to lysine in TSST-ovine. Like TSST-1, TSST-ovine was mitogenic, but unlike TSST-1, it was not pyrogenic, was unable to enhance endotoxic shock, and was unable to induce TSS in a rabbit model. Also, TSST-ovine was less reactive to certain monoclonal antibodies raised against TSST-1.

Amino Acid Sequence↗
PubMed1991

Effects of staphylococcal toxic shock syndrome toxin 1 on aortic endothelial cells.

In staphylococcal toxic shock syndrome, hypotension and shock due to capillary leak may rapidly lead to death of the host. To investigate its pathogenesis, the cytotoxic effects of toxic shock syndrome toxin 1 (TSST-1) on porcine aortic endothelial cells (PAEC) were examined in vitro. TSST-1 killed PAEC (as measured by 51Cr release) in a dose- and time-dependent fashion and was blocked by anti-TSST-1 antibodies. Receptor-mediated endocytosis may be critical for the cytotoxic effects of TSST-1, as killing was inhibited by cold (4 degrees C) and by addition of chloroquine and methylamine. Furthermore, calcium and oxygen appeared necessary for TSST-1 effects on PAEC. Membrane receptor binding studies indicated PAEC bind TSST-1 with high affinity (Kd = 5.7 x 10(-7) M) and had 2.2 x 10(4) receptors/cell. Last, as measured by 125I-labeled albumin flux in a transendothelial permeability model, TSST-1 enhanced the permeability of PAEC monolayers in a dose- and time-dependent manner.

Animals↗
PubMed1991

Cell and receptor requirements for streptococcal pyrogenic exotoxin T-cell mitogenicity.

Streptococcal pyrogenic exotoxins (SPEs) A, B, and C, like other members of the pyrogenic toxin family, are able to cause toxic shock-like syndromes. One of the major properties of these toxins is the ability to induce T-cell proliferation. Characterization of T cell mitogenicity associated with SPEs A, B, and C was undertaken. SPEs A, B, and C were mitogenic for C57BL10/SnJ and BALB/cWAT T cells, with activities differing in intensity depending on the mouse strain and toxin employed. SPE-induced, T-cell-proliferative activity was dependent on class II major histocompatibility complex molecules expressed on antigen-presenting cells. The abilities of SPEs A, B, and C to preferentially stimulate murine cells with certain T-cell receptor V beta s were investigated by fluorescence-activated cell sorter analysis. SPE A preferentially activated T cells expressing V beta 8 but not V beta 3, 6, or 11, while SPEs B and C preferentially stimulated T cells which did not express any of the tested V beta s.

Animals↗
PubMed1991

Fluid replacement protection of rabbits challenged subcutaneous with toxic shock syndrome toxins.

Toxic shock syndrome toxin 1 (TSST-1) and streptococcal pyrogenic exotoxin A (SPE A) belong to a family of pyrogenic toxins produced by Staphylococcus aureus and Streptococcus pyogenes, respectively. Both toxins are responsible for causing toxic shock syndrome (TSS) and related illnesses, clinically characterized by multiorgan involvement. The most severe TSS symptom is acute hypotension and shock after the initial febrile response. In this study, we examined possible mechanisms of shock development in TSS, particularly the role of T-cell proliferation, endotoxin enhancement by toxins, and capillary leakage. American Dutch belted rabbits, with subcutaneously implanted miniosmotic pumps filled with either TSST-1 or SPE A, served as the animal model. For both TSST-1 and SPE A-treated rabbits, administration of cyclosporin A prevented toxin-induced T-cell proliferation but failed to protect the rabbits. Polymyxin B treatment of rabbits, to neutralize endogenous endotoxin, partially protected rabbits from challenge with either exotoxin; two of six rabbits survived on day 2 when treated with only TSST-1, whereas six of six animals survived after challenge with TSST-1 and polymyxin B. Similarly, with SPE A-treated rabbits, only 1 of 10 animals without polymyxin B treatment survived on day 8, but 4 of 6 rabbits survived on day 8 when given polymyxin B. Fluid replacement was successful in preventing lethality. Twelve of 14 rabbits survived when given TSST-1 with fluid, and all rabbits treated with SPE A and fluid survived. Finally, by using miniosmotic pumps, staphylococcal exfoliative toxin A and concanavalin A were administered to rabbits in an attempt to induce lethality. These two T-cell mitogens caused T-cell proliferation but failed to induce lethality in rabbits. The data suggest that toxin interactions causing vascular leakage and to some extent endotoxin enhancement are of major importance in development of hypotension and shock in TSS. It appears that T-cell proliferation may not contribute significantly to the induction of shock and death.

Animals↗
PubMed1990

Atypical hepatic vein leiomyoma extending into the right atrium: an unusual cause of the Budd-Chiari syndrome.

A 14-year-old male presented with a one week history of weakness, lightheadedness and vomiting. Bilateral pleural effusions were evident on chest radiography; electrocardiogram revealed decreased voltages. Echocardiogram, abdominal ultrasound and magnetic resonance imaging revealed a mass in an hepatic vein and the inferior vena cava extending up to and filling the right atrium. Under deep hypothermia and extracorporeal circulation the mass was removed en bloc. It originated from the hepatic vein. Pathology revealed a smooth muscle tumour intermediate between benign and malignant (atypical leiomyoma). This is the first reported pediatric primary leiomyoma of the hepatic vein. It caused the Budd-Chiari syndrome, a rare pediatric entity.

Actins↗
PubMed1989

Quantification and toxicity of group A streptococcal pyrogenic exotoxins in an animal model of toxic shock syndrome-like illness.

Toxic shock-like syndrome isolates of group A streptococci were evaluated for production of pyrogenic exotoxins (also called SPEs, scarlet fever toxins, and erythrogenic toxins). The isolates were consecutively obtained during 1987 and 1988. Of these isolates, 23 of 26 made SPE type A, 10 of 26 made SPE B, and 8 of 26 made SPE C. SPE A was produced in significantly greater amounts than SPEs B and C (3.2 micrograms/ml of culture fluid compared with 0.7 and 0.6 microgram/ml, respectively). SPE A, administered in miniosmotic pumps implanted subcutaneously in rabbits, was significantly more toxic than SPE C; seven of eight rabbits succumbed after challenge with 150 or 300 micrograms of SPE A, compared with one of six after challenge with SPE C.

Animals↗
PubMed1988

Studies on the submicrosomal fractions of bovine oligodendroglia: lipid composition and glycolipid biosynthesis.

Oligodendroglia were isolated from bovine brain, and a "crude" microsomal fraction obtained from cell homogenates was subfractionated into myelin (MP), plasma membranes (PM), Golgi (GF), smooth (SER) and rough (RER) endoplasmic membranes using discontinuous-sucrose gradient centrifugation. The submicrosomal fractions were characterized by ultrastructural examination and analysis of the specific organelle markers. The myelin and plasma membrane rich fractions contained characteristically the highest amounts of the lipid with lower mole percentages of total phospholipids and phosphatidylcholine, and higher concentrations of phosphatidylethanolamine (+ plasmalogens), cholesterol and galactolipids. Considerable amounts of the typical myelin galactolipids (galacto-cerebrosides, sulfatides and monogalactosyl diglycerides) were also found in the Golgi fraction (GF). The GF fraction had the greatest enrichment of glycolipid-forming galactosyltransferases, and the distribution of these enzymes correlated well with that of the Golgi marker enzymes. The results give evidence that intracellular Golgi apparatus of oligodendroglia is rich in the myelin-specific lipids, and suggest its involvement in the synthesis and processing of myelin lipids.

Animals↗
PubMed1987

A comparison of the incidence and nature of cardiac dysrhythmias occurring during enflurane and isoflurane anaesthesia for dental surgery.

The incidence and nature of dysrhythmias with equipotent concentrations of enflurane and isoflurane during dental surgery were compared. Seventy-six Chinese patients between 17-30 years, of ASA Grade I, randomly received either enflurane or isoflurane with N2O and O2 for spontaneous ventilation during third molar extractions. The cardiac rhythm and the blood pressure were continuously monitored during the procedure. The incidence of dysrhythmias with both enflurane and isoflurane was low and the difference not statistically significant. During surgery one patient exhibited unifocal ventricular ectopics with isoflurane. Sinus tachycardia was common with both agents. No life-threatening dysrhythmias were seen with either agent and no clinically significant lowering of blood pressure occurred in association with the exhibited dysrhythmias. In this Chinese population, as in other studies, the incidence of dysrhythmias with both agents was low thus showing no difference between the races.

Adolescent↗
PubMed1986

Radiological diagnosis of leiomyosarcoma of the inferior vena cava.

A 46-year-old lady with leiomyosarcoma of the inferior vena cava extending into the hepatic veins and right atrium is described. The diagnosis was made preoperatively by a combination of radiological techniques including computed tomography, inferior vena cavography, arteriography, and two-dimensional echocardiography. The clinical presentation, radiological features and management of this condition are reviewed.

Female↗
PubMed1986

Combined use of warfarin and adjusted subcutaneous heparin during pregnancy in patients with an artificial heart valve.

Adjusted subcutaneous heparin was used for thromboembolism prophylaxis during 18 pregnancies in 16 women with an artificial heart valve. Oral warfarin was replaced by subcutaneous heparin as soon as pregnancy was confirmed. The dosage of heparin was adjusted to maintain a partial thromboplastin time at 1.5 times the control value and treatment was administered during the first trimester and the last 3 weeks of gestation. Warfarin was used between the 13th and 37th week. There were no maternal thromboembolic complications and none of the live-born infants showed congenital malformations, indicating that this regimen is effective. However, there were nine spontaneous abortions, including five that occurred in the first 12 weeks. The early abortions were probably related to warfarin exposure at the beginning of pregnancy. The preconception replacement of warfarin by heparin in these patients may be indicated.

Abortion, Spontaneous↗
PubMed1986

Comparison of the incidence and nature of cardiac arrhythmias occurring during isoflurane or halothane anaesthesia. Studies during dental surgery.

Seventy-six Chinese patients aged between 15 and 30 yr, undergoing 3rd molar extraction, were randomly allocated to two groups. One group received halothane and the other isoflurane. The incidence of arrhythmia during surgery under anaesthesia with isoflurane was significantly less than with halothane. Sinus tachycardia was a significant feature under anaesthesia with isoflurane. Under anaesthesia with halothane, the arrhythmias occurring most frequently during surgery were ventricular ectopics, the commonest being ventricular bigeminy. The frequency and nature of arrhythmias during surgery on right and left sides were similar. In three patients a slight decrease in arterial pressure was recorded in association with the arrhythmia, but on stopping the stimulus, both rhythm and arterial pressure returned to normal. The incidence of arrhythmia with halothane in the Chinese population in this study was significantly higher than that reported previously in non-Chinese patients.

Adolescent↗