Biomedical subjects

S Lee

Publications and source records attributed to S Lee.

At least 775 records · Page 43Linked to original sources

PubMed1997

Absence of microsatellite instability during the progression of chronic myelocytic leukemia.

Microsatellites are highly polymorphic, short-tandem repeat sequences dispersed throughout the genome. To test the occurrence of genetic instability in the progression of chronic myelocytic leukemia (CML), we studied microsatellite instability (MSI) in 17 patients with CML. The DNAs from both chronic phase and blast crisis were analyzed at 10 loci. No MSI was observed in any of the 17 cases of blast crisis. These results indicate that MSI is rare and is not associated with progression to blast crisis in most cases of CML.

Blast Crisis↗

PubMed1997

Microsatellite instability during the progression of acute myelocytic leukaemia.

We studied microsatellite instability (MSI) at the onset and during progression of 17 individuals with acute myelocytic leukaemia (AML). These included two cases of MO, eight with M1 and seven with M4, according to the FAB classification. The DNA from diagnostic, remission and relapsed stages of their disease was analysed at 69 loci. Two MSI were found in the diagnostic and remission phase paired samples (12%), and eight MSI were identified in six of the relapsed phase samples (35%). These results indicate that mismatch repair errors such as MSI are unimportant at the onset of AML, but might have importance during the progression of the disease.

Acute Disease↗

PubMed1997

Molecular basis of Kell blood group phenotypes.

The molecular basis of different Kell blood group phenotypes is reviewed. Sequence analysis of the Kell gene (KEL) established that single base substitutions, resulting in amino acid changes, are responsible for the different phenotypes. Most of the amino acid substitutions, with the exception of the one responsible for expression of KEL6 (Jsa), occur at the amino-terminal half of the protein, a domain that has least amino acid homology with a family of zinc endopeptidases, which include neutral endopeptidase 24.11 and endothelin-converting enzyme-1. Some of the genes were expressed in transfected cells and typed with alloantibodies to confirm that the identified mutations are responsible for antigen expression. Clinical applications of Kell blood group genotyping which include prenatal diagnosis to monitor hemolytic disease of the newborn are discussed.

Amino Acid Sequence↗

PubMed1997

The KEL24 and KEL14 alleles of the Kell blood group system.

BACKGROUND: The Kell blood group system consists of at least 21 antigens, which may be classified into five sets of alleles and at least 10 independently expressed antigens. The molecular basis of four of the five sets of alleles has been described; point mutations in KEL leading to amino acid substitutions characterize the alleles. In this study, the point mutation associated with the remaining allele, KEL14/KEL24, was determined. STUDY DESIGN AND METHODS: The 19 exons of KEL were amplified from genomic DNA by a polymerase chain reaction (PCR) procedure. The PCR products were sequenced. DNA sequences from unrelated KEL:14,24 and KEL:-14,24 individuals were compared to the DNA sequence of the common KEL:14,-24 phenotype. RESULTS: DNA from the KEL:14,24 person yielded both G and C at nt 659, indicating an Arg and Pro polymorphism in amino acid residue 180 of Kell protein. DNA from the KEL:-14,24 person had a G659C mutation in exon 6, indicating an Arg180Pro substitution. The G659C change introduces an Hae III restriction enzyme site, which was used to confirm the base mutations by restriction fragment length polymorphism analysis of the PCR products. CONCLUSION: A G659C mutation, predicting an Arg180Pro change in Kell protein, is associated with the KEL14/KEL24 allele.

Alleles↗

PubMed1997

A randomized, double-blind, placebo-controlled trial of cidofovir gel for the treatment of acyclovir-unresponsive mucocutaneous herpes simplex virus infection in patients with AIDS.

The safety and efficacy of cidofovir gel for treatment of acyclovir-unresponsive herpes simplex virus infections in AIDS patients was evaluated in a randomized, double-blind, multicenter trial. Cidofovir (0.3% or 1%) or placebo gel was applied once daily for 5 days. Ten of 20 cidofovir-treated and none of 10 placebo-treated patients had complete healing or >50% decreased area (P = .008); 30% of cidofovir-treated patients versus 0 placebo recipients had complete healing (P = .031). Viral shedding ceased in 13 (87%) of 15 cidofovir-treated and 0 of 9 placebo-treated patients (P = .00004). For cidofovir-treated patients, median time to complete or good response was 21 days, and median time to negative viral culture was 2 days (P = .025, P = .0001, respectively). Median lesion area decreases were 58% for cidofovir-treated versus 0 for placebo-treated patients (P = .005), and mean pain score changes were -1.84 versus -0.34 (P = .042). Application site reactions occurred in 25% of cidofovir-treated and 20% of placebo-treated patients; none was dose-limiting. Cidofovir therapy provided significant benefits in lesion healing, virologic effect, and pain reduction.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Conformal radiotherapy computation by the method of alternating projections onto convex sets.

Synthesis of beam profiles for a given dose prescription is a central problem in radiotherapy. Care must be taken in the beam design to expose the tumour volume at a high level, to avoid significant irradiation of critical organs, and to minimize exposure of all other tissue. Use of the synthesis procedure known as alternating projections onto convex sets (POCS) is shown to be a viable approach to beam design. POCS is a powerful tool for signal and image restoration and synthesis. Convex sets of signals obeying desired constraint sets are first specified. Then, by repeated projections onto these sets, convergence is to a signal obeying all desired constraints if the constraint sets have a finite intersection. In this paper we apply the method of POCS to conformal radiotherapy dose computation. The performance of the method is shown through three representative examples.

Algorithms↗

PubMed1997

Insecticidal activity of monoterpenoids to western corn rootworm (Coleoptera: Chrysomelidae), twospotted spider mite (Acari: Tetranychidae), and house fly (Diptera: Muscidae).

Acute toxicities of 34 naturally occurring monoterpenoids were evaluated against 3 important arthropod pest species; the larva of the western corn rootworm, Diabrotica virgifera virgifera LeConte; the adult of the twospotted spider mite. Tetranychus urticae Koch; and the adult house fly. Musca domestica L. Potential larvicidal or acaricidal activities of each monoterpenoid were determined by topical application, leaf-dip method, soil bioassay, and greenhouse pot tests. Phytotoxicity was also tested on a corn plant. Citronellic acid and thymol were the most topically toxic against the house fly, and citronellol and thujone were the most effective on the western corn rootworm. Most of the monoterpenoids were lethal to the twospotted spider mite at high concentrations; carvomenthenol and terpinen-4-ol were especially effective. A wide range of monoterpenoids showed some larvicidal activity against the western corn rootworm in the soil bioassay. Perillaldehyde, the most toxic (LC50 = 3 micrograms/g) in soil, was only 1/3 as toxic as carbofuran, a commercial soil insecticide (LC50 = 1 microgram/g). Selected monoterpenoids also effectively protected corn roots from attack by the western corn rootworm larvae under greenhouse conditions. alpha-Terpineol was the best monoterpenoid in the greenhouse pot test. The acute toxicity of monoterpenoids was low relative to conventional insecticides. Some monoterpenoids were phytotoxic to corn roots and leaves. l-Carvone was the most phytotoxic, whereas pulegone was the safest. The results with thymyl ethyl ether, one of the synthetic derivatives of thymol, showed a potential of derivatization to reduce monoterpenoid phytotoxicity.

Animals↗

PubMed1997

Effect of repeated activin-A treatment on the activity of the hypothalamic-pituitary-gonadal axis of the adult male rat.

The present study was undertaken to determine whether recombinant activin-A increases mRNA levels of the peptide GnRH, and whether this phenomenon correlates with increased FSH and/or LH release. One acute s.c. injection of activin-A (120 micrograms/kg body weight) to adult male rats was found to significantly (P < 0.01) increase plasma FSH levels, with no detectable changes in LH or testosterone (T) release. Similarly, there were no significant differences between GnRH mRNA values measured in the medial preoptic area of the hypothalamus. When activin-A was administered s.c. every 8 h for seven consecutive treatments, similar results were obtained for gonadotropin release; in addition, we observed a significant (p < 0.01) up-regulation of hypothalamic GnRH mRNA levels. The administration of activin-A intracerebroventricularly (i.c.v., 6 micrograms/rat) according to the same chronic schedule also produced a significant (p < 0.01) increase in FSH levels, as well as a modest, but detectable, elevation in LH concentrations, and a large augmentation of T secretion. In contrast, there were no changes in steady-state GnRH mRNA concentrations. Collectively, these results show that both the systemic (s.c.) and the central (i.c.v.) injection of activin-A stimulates FSH secretion. While we had originally thought that the lack of response of hypothalamic GnRH neurons to i.c.v. activin injections might have been due to increased steroid feedback, the observation that comparable results were obtained in both intact and castrated rats does not support this hypothesis. One possibility is that the previously reported stimulatory influence of i.c.v. activin-A treatment on neurons that manufacture corticotropin-releasing factor, and consequently on circulating catecholamine concentrations, may have increased testicular activity independently of changes in pituitary function.

Activins↗

PubMed1997

Nonreamed locking intramedullary nailing for open fractures of the tibia.

The use of nonreamed interlocking tibial nails in the management of open fractures of the tibial shaft has gained wide acceptance. This technique has been reported to have reproducible good results with a low incidence of complications in Type I, Type II, and Type IIIA open tibial shaft fractures. The use of nonreamed nails in Type IIIB fractures continues to be a source of controversy. The treatment of 72 open fractures of the tibial shaft with nonreamed interlocking intramedullary nailing is detailed. There were 27 Type I, 22 Type II, 11 Type IIIA, and 12 Type IIIB open tibial shaft fractures. There were three (4.2%) deep infections; one Type II, one Type IIIA, and one Type IIIB. Forty-nine fractures (68%) united by 6 months, all fractures had united by 12 months. The use of nonreamed locking intramedullary nailing in Types I, II, IIIA, and IIIB open fractures of the tibial shaft is supported.

Adolescent↗

PubMed1997

Lithium pharmacokinetics in Chinese manic-depressive patients.

The pharmacokinetics of lithium was studied in 16 manic-depressive Chinese adults who were on lithium therapy in Hong Kong. A two-compartment open model was used to describe the plasma data obtained. The steady-state volume of distribution and total plasma clearance were estimated to be 63.4 +/- 38.3 L and 1.47 +/- 0.49 L/hr, respectively, which were similar to those reported in studies of Caucasian subjects. The lithium clearance was found to be significantly related to lean body mass (r = 0.646, p < 0.01) but not to either total body weight, age, or creatinine clearance. Interindividual variability in lithium clearance was substantially reduced to a coefficient of variation of 24.6% from 33.3% when lean body mass was considered. The combined plasma and urine data indicate that the rate and extent of lithium absorption were similar to those of earlier studies in Caucasian subjects on a standard lithium dosage.

Adult↗

PubMed1997

Microvascular anastomotic thrombosis in experimental diabetes mellitus.

An experimental model was developed to investigate the effects of glycemic control and pentoxifylline administration on microvascular anastomotic patency rates in streptozotocin-induced diabetic rats. Diabetes was confirmed by blood glucose levels of more than 300 mg/dl prior to administering insulin and/or pentoxifylline. Microvascular anastomoses of the femoral artery and vein were performed 4 weeks after induction of diabetes. Subsequently, the comparative rates of anastomotic thrombosis in diabetic and nondiabetic groups with or without insulin or pentoxifylline administration were assessed by direct visualization of the anastomotic sites after 4 days. The results suggest that hyperglycemia impairs the post-operative patency of microvascular venous anastomoses. The diabetic animals maintained under insulin regimens that tightly controlled their serum glucose levels (100 to 200 mg/dl) experienced patency rates similar to those of nondiabetic controls (p < 0.05). Pentoxifylline improved microvenous patency at all levels of hyperglycemia studied, suggesting a possible hemorrheologic mechanism for microvascular venous anastomotic thrombus formation in diabetic animals.

Anastomosis, Surgical↗

PubMed1997

A novel threonine --> proline mutation at the end of 2B rod domain in the keratin 2e chain in ichthyosis bullosa of Siemens.

We report a novel mutation in a case of ichthyosis bullosa of Siemens that results in a threonine --> proline substitution in a novel location, codon 485 in a highly conserved residue position of the IATYRKLLEGE consensus motif at the end of the 2B rod domain segment of the keratin 2e chain. The disease phenotype is consistent with the inappropriate substitution of a proline near the end of the rod domain, because it lies near the predicted molecular overlap region of coiled-coil molecules, which is critical for the maintenance of the structural integrity of keratin intermediate filaments.

Biopsy↗

PubMed1997

Effect of three different modes of alcohol administration on the activity of the rat hypothalamic-pituitary-adrenal axis.

The present study compared the effect of different modes of alcohol administration on the activity of the hypothalamic-pituitary-adrenal (HPA) axis. In a first series of studies, we investigated the influence of the intraperitoneal (ip) and intragastric (ig) effect of acutely administered alcohol. Over a 3-hr period, alcohol induced dose-related increases in adrenocorticotropic hormone (ACTH) and alcohol levels in the circulation. There was a good correlation between blood ACTH and alcohol levels (ip treatment, R = 0.84; ig treatment, R = 0.79). Measurement of steady-state mRNA of the immediate early gene NGFI-B, taken as an index of neuronal activation in the paraventricular nucleus (PVN) of the hypothalamus of rats administered 3 g of alcohol/kg, indicated significant (p < 0.01) increases between 60 and 180 min after both ip and ig alcohol injection, with peak stimulation at 1 and 2 hr, respectively. Although NGFI-B mRNA levels had returned to control level in the parvicellular portion of the PVN of animals administered the drug ip 4 hr earlier, they were still significantly (p < 0.01) elevated 4 hr after ig treatment. A second series of studies used rats fed an alcohol diet containing 6.4% alcohol (w/v), or pair-fed. The rats were tested during the 4th or 6th night of treatment. Despite blood alcohol levels ranging between 0.060 and 0.140% w/v, there was no significant rise in plasma ACTH/corticosterone levels in animals fed the drug, and no detectable NGFI-B mRNA in their PVN. Collectively, these results indicate that both the ip and the ig acute injection of alcohol induced dose-related increases in plasma ACTH levels. PVN neuronal activation was also observed. In contrast, the alcohol diet had no effect on HPA hormone levels or PVN expression of NGFI-B.

Administration, Oral↗

PubMed1997

Enhancement of human immunodeficiency virus type 1 envelope-mediated fusion by a CD4-gp120 complex-specific monoclonal antibody.

The entry of human immunodeficiency virus type 1 (HIV-1) into cells is initiated by binding of the viral glycoprotein gp120-gp41 to its cellular receptor CD4. The gp120-CD4 complex formed at the cell surface undergoes conformational changes that may allow its association with an additional membrane component(s) and the eventual formation of the fusion complex. These conformational rearrangements are accompanied by immunological changes manifested by altered reactivity with monoclonal antibodies specific for the individual components and presentation of new epitopes unique to the postbinding complex. In order to analyze the structure and function of the gp120-CD4 complex, monoclonal antibodies were generated from splenocytes of BALB/c mice immunized with soluble CD4-gp120 (IIIB) molecules (J. M. Gershoni, G. Denisova, D. Raviv, N. I. Smorodinsky, and D. Buyaner, FASEB J. 7:1185-1187 1993). One of those monoclonal antibodies, CG10, was found to be strictly complex specific. Here we demonstrate that this monoclonal antibody can significantly enhance the fusion of CD4+ cells with effector cells expressing multiple HIV-1 envelopes. Both T-cell-line-tropic and macrophage-tropic envelope-mediated cell fusion were enhanced, albeit at different optimal doses. Furthermore, infection of HeLa CD4+ (MAGI) cells by HIV-1 LAI, ELI1, and ELI2 strains was increased two- to fourfold in the presence of CG10 monoclonal antibodies, suggesting an effect on viral entry. These findings indicate the existence of a novel, conserved CD4-gp120 intermediate structure that plays an important role in HIV-1 cell fusion.

Animals↗

PubMed1997

Human immunodeficiency virus type 1 infection of mature CD3hiCD8+ thymocytes.

Although CD4+ cells are the primary targets of human immunodeficiency virus type 1 (HIV-1) infection, earlier reports have suggested that intrathymic infection of CD8+ cells may occur. However, it was unclear whether HIV-1-infected CD8+ thymocytes were truly mature single-positive (SP) cells. In the present study, SCID mice implanted with human fetal thymus and liver tissues (SCID-hu mice) were infected with three primary isolates of HIV-1 and infected thymocytes were analyzed to assess maturational status. After intra-implant or intraperitoneal injection with HIV-1, thymocytes were sorted by three-color flow cytometric analysis into mature populations of CD3hiCD4+ and CD3hiCD8+ SP cells of > 99% purity (< 0.3% CD4-containing cells in the CD8+ population). The presence of HIV-1 provirus in the sorted thymocyte populations was determined by quantitative PCR. A fraction of mature CD3hiCD8+ thymocytes contained HIV-1 proviral DNA, and evidence of viral mRNA transcription in these cells was demonstrated by in situ hybridization. In contrast, when uninfected CD3hiCD8+ thymocytes were cocultured with HIV-1-infected CD4+ thymocytes, no evidence of productive HIV-1 infection was detected. Thus, HIV-1 infection of CD8+ thymocytes in the SCID-hu mouse does not occur by direct contact with the virus. Rather, cell surface CD4 is required; therefore, precursor cells are the likely primary target of HIV-1 infection in the thymus. During ontogeny, some of these infected cells continue their differentiation into mature CD8+ SP thymocytes that contain proviral DNA and express viral RNA.

Animals↗

PubMed1997

Functional interactions between monomers of the retroviral envelope protein complex.

Retroviral vectors have been widely used in human gene therapy protocols. Entry into target cells is directed by the retroviral envelope protein, with receptor binding and postbinding fusion functions contributed mainly by the SU and TM subunits, respectively. We have generated mutants of the Moloney murine leukemia virus (MoMuLV) envelope protein with mutations in both the receptor binding domain of SU and throughout the TM subunit that are functionally inactive when expressed individually. However, the coexpression of these two classes of mutants partially restores envelope protein function and allows transduction. Several lines of evidence indicate that this complementation occurs in trans within envelope protein heterooligomers. The finding that the binding and postbinding functions of a retroviral envelope protein can be contributed by two different monomers should assist in the engineering of envelope proteins for tissue-specific gene delivery.

3T3 Cells↗

PubMed1997

Mutation in the Jak kinase JH2 domain hyperactivates Drosophila and mammalian Jak-Stat pathways.

The Jak (Janus) family of nonreceptor tyrosine kinases plays a critical role in cytokine signal transduction pathways. In Drosophila melanogaster, the dominant hop(Tum-l) mutation in the Hop Jak kinase causes leukemia-like and other developmental defects. Previous studies have suggested that the Hop(Tum-l) protein might be a hyperactive kinase. Here, we report on the new dominant mutation hop(T42), which causes abnormalities that are similar to but more extreme than those caused by hop(Tum-l). We determined that Hop(T42) contains a glutamic acid-to-lysine substitution at amino acid residue 695 (E695K). This residue occurs in the JH2 (kinase-like) domain and is conserved among all Jak family members. We determined that Hop(Tum-1) and Hop(T42) both hyperphosphorylated and hyperactivated D-Stat when overexpressed in Drosophila cells. Moreover, we found that the hop(T42) phenotype was partially rescued by a reduction of wild-type D-stat activity. Finally, generation of the corresponding E695K mutation in murine Jak2 resulted in increased autophosphorylation and increased activation of Stat5 in COS cells. These results demonstrate that the mutant Hop proteins do indeed have increased tyrosine kinase activity, that the mutations hyperactivate the Hop-D-Stat pathway, and that Drosophila is a relevant system for the functional dissection of mammalian Jak-Stat pathways. Finally, we propose a model for the role of the Hop-D-Stat pathway in Drosophila hematopoiesis.

Amino Acid Sequence↗

PubMed1997

New mechanoenergetic evaluation of left ventricular contractility in in situ rat hearts.

We recorded a series of ejecting left ventricular (LV) pressure (P)-volume (V) loops of in situ rat hearts during a gradual ascending aortic occlusion. The end-systolic (ES) P-V relationship (ESPVR) was upward convex curvilinear regardless of LV contractility. The ESPVR was shifted upward in an enhanced contractility by dobutamine and downward in a depressed contractility by propranolol; ESP at a midrange V of 0.1 ml/g LV on each ESPVR increased from 131 +/- 11 to 192 +/- 17 mmHg and decreased from 136 +/- 10 to 110 +/- 7 mmHg, respectively. Furthermore, we obtained an upward concave curvilinear pressure-volume area (PVA; a measure of total mechanical energy)-V (preload) relationship to assess LV work capability in each contractility. This relationship also shifted upward in enhanced contractility and downward in depressed contractility; the PVA at midrange V increased from 7.9 +/- 1.2 to 12.3 +/- 1.5 mmHg. ml.beat-1.g-1 and decreased from 8.2 +/- 0.9 to 6.4 +/- 0.8 mmHg.ml.beat-1.g-1. We conclude that the heights of the ESPVR and PVA-V relationship curves can evaluate LV contractility mechanoenergetically.

Animals↗