Search PubMed⌕ Search

Biomedical subjects

A Kim

Publications and source records attributed to A Kim.

At least 109 records · Page 6Linked to original sources
PubMed1996

cDNA sequence and genomic structure of the murine p55 (Mpp1) gene.

MPP1 is an X-linked human gene encoding a heavily palmitoylated membrane protein (p55) with homology to the Drosophila tumor suppressor gene lethal(1) discs-large. As a first step toward studying the effects of mutations in this gene in a mammalian system, the nucleotide sequence of the mouse Mpp1 cDNA has been determined along with the intron-exon boundaries. Mpp1 is ubiquitously expressed and encodes a p55 protein of 466 amino acids with 93 and 65% identity to the human and puffer fish (Fugu rubripes) p55 sequences, respectively. The genomic structure of the Mpp1 gene is likewise conserved with 12 exons. The location of the Mpp1 gene, on the X chromosome, is also conserved between the human and the mouse. Conservation of the Mpp1 gene between mouse and human gives support to the notion that construction and study of a mouse knockout model may help establish the function of the human MPP1 gene, a potential tumor suppressor gene.

Amino Acid Sequence↗
PubMed1996

An update on core needle biopsy for radiologically detected breast lesions.

BACKGROUND: Traditionally, radiologically detected lesions of the breast have been evaluated by open surgical biopsy with wire localization. Recently, core needle biopsy has been introduced as an alternative to open surgical biopsy. The authors evaluated their own results with long term follow-up after core needle biopsy and reviewed the experience of other physicians with this new technique. METHODS: Four hundred thirty-one core needle biopsies performed at UCLA were analyzed. The outcome of these cases was determined by either surgery or long term follow-up. Statistical analysis was performed to determine the accuracy of the method. RESULTS: Definitive outcome was obtained in 96% of the core needle biopsy cases, with a median follow-up time of 18 months (range, 6-38 months). The authors achieved a sensitivity of 99% and a specificity of 100%. The false-negative rate was 1.7%. There were no complications in this series. CONCLUSIONS: Core needle biopsy is a highly accurate and safe method for the diagnosis of radiologically detected lesions of the breast.

Biopsy, Needle↗
PubMed1996

Role of protein kinase C-beta isozyme in activation of latent human immunodeficiency virus type 1 in promonocytic U1 cells by phorbol-12-myristate acetate.

Protein kinase C (PKC) appears to play a role in replication of human immunodeficiency virus type 1 (HIV-1). PKC is a family of at least 12 isozymes. In this study, we investigated a role of Ca(2+)-dependent PKC isozymes (alpha, beta, and gamma) in activation of latent HIV-1 in U1, a chronically infected promonocytic cell line, using polyclonal rabbit anti-PKC isozyme antibodies as specific inhibitors. Antibodies were introduced intracellularly by electroporation and then cells were stimulated with PMA. HIV-1 production was measured as p24 antigen using ELISA and reverse transcriptase activity. Anti-PKC beta antibody significantly inhibited PMA-induced HIV-1 production, whereas antibodies against PKC alpha and gamma had no significant effect. Furthermore, anti-PKC beta antibody inhibited PMA-induced activation of NF-kappa B and HIV-1 LTR. Preincubation of anti-PKC beta antibody with its antigenic peptide reversed the inhibitory effect of anti-PKC beta antibody. This study suggest that PKC beta plays a role in PMA-induced activation of latent HIV-1.

Animals↗
PubMed1996

Inhibition of acute in vivo human immunodeficiency virus infection by human interleukin 10 treatment of SCID mice implanted with human fetal thymus and liver.

To improve the usefulness of in vivo mode for the investigation of the pathophysiology of human immunodeficiency virus (HIV) infection, we modified the construction of SCID mice implanted with human fetal thymus and liver (thy/liv-SCID-hu mice) so that the peripheral blood of the mice contained significant numbers of human monocytes and T cells. After inoculation with HIV-1(59), a primary patient isolate capable of infecting monocytes and T cells, the modified thy/liv-SCID-hu mice developed disseminated HIV infection that was associated with plasma viremia. The development of plasma viremia and HIV infection in thy/liv-SCID-hu mice inoculated with HIV-1(59) was inhibited by acute treatment with human interleukin (IL) 10 but not with human IL-12. The human peripheral blood mononuclear cells in these modified thy/liv-SCID-hu mice were responsive to in vivo treatment with exogenous cytokines. Human interferon gamma expression in the circulating human peripheral blood mononuclear cells was induced by treatment with IL-12 and inhibited by treatment with IL-10. Thus, these modified thy/liv-SCID-hu mice should prove to be a valuable in vivo model for examining the role of immunomodulatory therapy in modifying HIV infection. Furthermore, our demonstration of the vivo inhibitory effect of IL-10 on acute HIV infection suggests that further studies may be warranted to evaluate whether there is a role for IL-10 therapy in preventing HIV infection in individuals soon after exposure to HIV such as for children born to HIV-infected mothers.

Animals↗
PubMed1996

Evidence of cortical metabolic dysfunction in early Huntington's disease by single-photon-emission computed tomography.

We compared perfusion of prefrontal, motor, and sensory cortices and basal ganglia in 29 Huntington's disease (HD) patients and nine controls. We found a significant reduction in perfusion in patients with HD of short (< 6 years, n = 10), medium (6-10 years, n = 8), and long duration (> 10 years, n = 11) compared with controls. Among short-duration patients, we observed decreases in cortical perfusion before evidence of atrophy on magnetic resonance imaging, suggesting that decreases in neuronal activity, as reflected by perfusion levels, precede gross structural changes. As expected, decreased perfusion was marked in basal ganglia. The extent of cortical perfusion correlated with clinical assessments of functional capabilities as well as with the duration of disease. Prefrontal perfusion correlated with cognitive measures, and motor cortical perfusion correlated with physical disability and activities of daily living scores. We found no significant clinical correlations with sensory cortical perfusion. Single-photon-emission computed tomography may be a sensitive method for assessing disease progression in clinical trials and pharmacologic intervention.

Adult↗
PubMed1996

SCID-hu mice: a model for studying disseminated HIV infection.

Modifications that we introduced into the implantation of human fetal thymus and liver into SCID mice (thy/liv-SCID-hu mice) markedly increased the population of human T cells and monocytes present in the peripheral blood and peripheral lymphoid compartment of these mice. As a result, the modified thy/liv-SCID-hu mice developed disseminated HIV infection after intraimplant or i.p. inoculation. After chronic HIV infection of these mice, depletion of the peripheral human T cells was observed as reported in HIV-infected individuals. In addition, these mice also developed plasma viremia after infection with HIV. The peripheral blood mononuclear cells were responsive to in-vivo cytokine regulation as evidenced by induction of human IFN-gamma gene expression by human IL-12 and inhibition by human IL-10. Acute treatment with human IL-10 but not with human IL-12 inhibited the development of plasma viremia and HIV infection in thy/liv-SCID-hu mice inoculated with HIV-1(59), a clinical isolate. SCID mice transplanted with cultured human fetal bone marrow displayed significant engraftment of the mouse bone marrow with human precursor cells and population of the peripheral blood with human B cells and monocytes. The peripheral blood of these bone marrow-transplanted SCID mice also became populated with human T cells after they were implanted with human thymic tissue due to migration of human precursor cells from the mouse bone marrow to the implanted human thymus. Thus, these modified SCID-hu mice should prove to be a valuable in-vivo model for studying the immunopathogenesis of HIV infection and for examining the in-vivo efficacy of immunomodulatory, drug and gene therapy in modifying HIV infection.

Animals↗
PubMed1996

Quantitative comparison of multiple myeloma tumor contamination in bone marrow harvest and leukapheresis autografts.

Autologous transplantation is increasingly being used to treat patients with multiple myeloma (MM). Recently, peripheral blood progenitor cell (PBPC) harvest have been preferred over autologous bone marrow (BM) harvests due to reduced engraftment time, ease of attainment, and presumptive reduction of occult tumor involvement. To resolve this latter assumption quantitatively, we have used the unique immunoglobulin (Ig) heavy chain variable region sequence of the patient's myeloma cell as a marker of clonality. Samples from PBPC collections and 'back-up' BM harvests were obtained from 13 patients with MM and analyzed for tumor contamination using patient-specific oligonucleotide primers and the polymerase chain reaction. As expected, the percentage of tumor cells contaminating the BM harvest (median, 0.74%) was higher than in the PBPC specimens (median, 0.0024%). Because of the increased total number of cells required for PBPC transplantation, the increase in total number of contaminating cells in the BM vs PBPC autografts was less pronounced, (BM:PBPC tumor contamination ratios ranging from 0.9 to > 4500; median, 14). This confirms that in most but not all cases unmanipulated PBPC products are preferable over BM harvests as a method of reducing myeloma autograft tumor contamination.

Adult↗
PubMed1996

Molecular analysis of a silent polymorphism in the PDZ domain of p55, the major palmitoylated erythrocyte membrane protein.

Two independently published cDNA sequences of p55, the X-linked major palmitoylated erythrocyte membrane protein, revealed a discrepancy between G and T at position 358 (Genbank: M64925). This results in codon 85, in exon 3 in the PDZ (PSD-95, discs-large, Z0-1) domain, being either ACG or ACT. As both ACG and ACT code for threonine, this represents a silent polymorphism. Polymerase chain reaction (PCR), single-stranded conformational polymorphism (SSCP), and direct-sequencing analysis of exon 3 of the p55 gene was performed in 98 subjects of African and European origin. Of the 70 females studied, the frequency of G versus T at position 358 was 0.76:0.24, while of the 28 males, 16 had a G and 12 a T at position 358 (0.57:0.43). In subjects of African origin, the frequency of G versus T at position 358 was 0.78:0.22; in subjects of European origin the ratio was 0.63:0.37.

Blood Proteins↗
PubMed1995

Antioxidant function of recombinant human natural killer enhancing factor.

Natural killer enhancing factor (NKEF) is a member of a new class of highly conserved antioxidant proteins. Members of this family have been described as thiol-specific antioxidants. In this study, we show that recombinant proteins encoded by the two human NKEF genes (nkef-A and B) possess antioxidant function in the protection of protein and DNA from oxidative damage. The production of separate proteins from each of the genes encoding NKEF is an important step in the elucidation of its function.

Antioxidants↗
PubMed1995

Host primary olfactory axons make synaptic contacts in a transplanted olfactory bulb.

Previous light microscopic studies have shown that host olfactory neurons are able to grow into a transplanted fetal olfactory bulb, and behavioral studies have shown that animals with transplanted olfactory bulbs recover functional olfactory abilities. We examined the olfactory bulb transplant at the ultrastructural level to determine whether synaptic contacts are reestablished between host olfactory neurons and donor olfactory bulb. Mature rats that, as neonates, had received embryonic olfactory bulb transplants following olfactory bulb removal were studied. An antibody specific for olfactory marker protein was used to identify the primary olfactory neurons; it was bound by a gold-conjugated secondary antibody for visualization. To preserve the antigenicity of the olfactory marker protein for immunolabeling, Lowicryl K4M hydrophilic resin was used. Synaptic contacts were unmistakable between labeled axons of host olfactory neurons and unlabeled processes within glomerulus-like areas of the transplanted olfactory bulb. The surrounding neuropil contained other elements similar to those found in normal tissue, including synaptic contacts between unlabeled profiles. We clearly show that the transplanted olfactory bulb exhibits sufficient plasticity to form an array of normal synaptic contacts, including the contacts from host primary olfactory neurons.

Animals↗
PubMed1995

Divergent effects of chronic HIV-1 infection on human thymocyte maturation in SCID-hu mice.

We have recently developed a modified SCID-hu mouse model in which the implanted human thymus and liver (hu-thy/liv) and human peripheral T cells become infected with HIV-1 after i.p. inoculation. By using this model, we evaluated the effect of HIV-1 infection on thymic maturation and observed that different HIV-1 strains had divergent effects of thymic maturation. Although minimal effects on continued thymopoiesis in the hu-thy/liv implant were observed after chronic infection with two primary patient isolates, HIV-1(28) and HIV-1(59), and with HIV-1ADA, HIV-1Ba-L, HIV-1JR-CSF, HIV-1JR-FL, and HIV-1SF162, significant thymocyte depletion was detected after infection with HIV-1IIIB and HIV-1RF. Thus, the effect of HIV-1 infection on thymocyte maturation may depend upon the strain of HIV-1 infecting the thymus. Despite the minimal effects on thymopoiesis observed in the hu-thy/liv implanted in SCID-hu mice 6 mo after infection with HIV-1(28), significant changes were seen in the human T cell population circulating in the peripheral blood of these mice. These changes ranged from an inversion of the CD4/CD8 ratio of peripheral human T cells in some SCID-hu mice to the almost complete depletion of peripheral human T cells observed in other SCID-hu mice. Because these effects were associated with the detection of HIV-1 infection of the peripheral human T cells, these modified SCID-hu mice should prove to be a valuable model for investigating the effects of chronic HIV-1 infection on the peripheral human T cell population.

Animals↗
PubMed1995

Multiple myeloma clones are derived from a cell late in B lymphoid development.

We have previously demonstrated that the immunoglobulin (Ig) heavy chain variable region (VH) sequences expressed by the malignant clone in multiple myeloma (MM) contain a high degree of somatic mutation without clonal diversity. This sequence can be used to identify all members of the malignant clone in this B cell malignancy. We sequenced the variable regions expressed by patients with MM and generated primers from the complementarity determining region (CDR) sequences specific for each patient's tumor. Using these primers, we performed PCR amplification on highly purified subpopulations of cells separated by expression of CD10, CD34 and CD38. The results of these experiments demonstrate: 1) there is a small fraction of CD10-expressing tumor cells in MM patients, 2) CD34-bearing malignant cells do not exist in MM, and 3) although the vast amount of tumor is in the CD38-expressing cells, a small amount of tumor is in the CD38-negative population. We also used these primers to determine whether pre-class switch (i.e., Cmu-expressing lymphocytes) clonal cells exist in these patients. After PCR amplification with CDR1 and Cmu primers, colony hybridization was performed using both framework 3 (FR3) and CDR3 probes. Out of > 200 FR3-hybridizing colonies, < or = 5 colonies also hybridized with the CDR3 probe. Colonies which hybridized with both these probes were sequenced, and none of these sequences matched even closely the CDR3 expressed by the malignant clone. These results make the existence of a pre-class switch malignant cell unlikely in MM. Overall, these results suggest that the malignant clone in MM derives from a cell late in B lymphocyte development.

ADP-ribosyl Cyclase↗
PubMed1995

Frontal cingulotomy reconsidered from a WGA-HRP and c-Fos study in cat.

A recent positron emission tomography (PET) study demonstrated that the anterior cingulate cortex (area 24), in addition to SI and SII cortices, was activated by painful stimuli. In order to elucidate the participation of relay nuclei in the ascending pain pathway to area 24, we performed a regrograde labelling study with WGA-HRP injection into area 24 in cats. Area 24 was found to receive pain-related thalamic inputs from the intralaminar nuclei including the central medial nucleus, midline nuclei, modiodorsal nucleus and possibly the submedial nucleus. We then examined the expression of Fos protein in CNS induced by formalin injection into the face in cats. Fos positive neurons were demonstrated in areas 23 and 24, the anterior limbic area, insular cortex, midline and paraventricular nuclei in the thalamus, paraventricular nucleus and other areas in the hypothalamus, and in many nuclei in the brainstem in both the formalin-injected group and the control group (anesthesia only). Labelled regions appeared to correspond to stress-related sites. The sole difference from the control group was the expression of Fos in the coronal gyrus and in the trigeminal caudalis nucleus in the experimental group. Although more Fos positive cells were observed in area 24 in experimental than in control cats, the difference was not significant. Our findings suggest that the demonstrated response of area 24 on PET scan represents stress- and emotion-related events rather than pain. Surgical intervention into the anterior cingulate cortex including cingulotomy thus appears to relieve stress and emotion associated with chronic pain, but not pain itself.

Animals↗
PubMed1995

Human immunodeficiency virus-1 principal neutralizing domain peptide-toxin A conjugate vaccine.

To enhance the potential efficacy of peptide-based vaccines for human immunodeficiency virus-1 (HIV-1), a principal neutralizing domain (PND) peptide (KRIHIGPGRAFYT) (HIV-1MN) was covalently coupled to Pseudomonas aeruginosa toxin A (TA). Immunization of guinea-pigs with this conjugate vaccine, in the absence of an adjuvant, engendered a high-affinity antibody response to the homologous HIV-1MN PND peptide and to analogous peptides from variant strains of HIV-1. A substantial proportion of such antibodies was directed to the conserved GPGRAF motif. Anti-PND peptide antibodies were capable of neutralizing the homologous strain, HIV-1MN, in addition to two heterologous (RF, IIIB) variants, as determined either by inhibition of syncytia formation or by suppression of p24 antigen production in cultured cells. Therefore, the method of conjugation used preserved critical neutralizing epitopes expressed by the PND peptide. Monovalent or polyvalent PND-TA conjugates, which meet all safety criteria for human use, are a promising approach towards the development of an acquired immunodeficiency syndrome (AIDS) vaccine.

ADP Ribose Transferases↗
PubMed1995

A sensitive and semi-quantitative pediatric myoclonus evaluation scale.

One of the difficulties in evaluating myoclonus in childhood is the lack of a standardized scale which addresses the constraints of pediatric scoring. The scale needs to be simple and rapid as well as sensitive and semi-quantitative and applicable across different ages. We videotaped children and young adults with myoclonus of various etiologies, such as progressive myoclonus epilepsy, opsoclonus-myoclonus and other acquired etiologies, and scored the videotapes using a new scale. Each clinical type of myoclonus (spontaneous, action and sensory-evoked myoclonus) was graded separately on a five-point scale for severity, intensity and distribution. Data were evaluated as separate scores and also combined for a total score. Validity and reliability were tested using a judge panel of three blinded, trained observers. Action myoclonus was the predominant form of myoclonus in our patients, and was significantly greater than spontaneous and sensory-evoked myoclonus in frequency, intensity and distribution. Separate statistical analysis performed for progressive myoclonus epilepsy and for opsoclonus-myoclonus showed the same pattern. Total scores between etiologies of myoclonus for frequency and distribution categories were significantly different. Subscores and total scores were highly correlated. We found the new scale to be flexible and adaptable for children and there were few missing values due to non-applicability of a scale item. It was useful for all pediatric age groups. The scale and videotape instructions provide a reliable tool for use in pediatric myoclonic disorders.

Adolescent↗
PubMed1995

Cloning of murine Stat6 and human Stat6, Stat proteins that are tyrosine phosphorylated in responses to IL-4 and IL-3 but are not required for mitogenesis.

By searching a database of expressed sequences, we identified a member of the signal transducers and activators of transcription (Stat) family of proteins. Human and murine full-length cDNA clones were obtained and sequenced. The sequence of the human cDNA was identical to the recently published sequence for interleukin-4 (IL-4)-Stat (J. Hou, U. Schindler, W.J. Henzel, T.C. Ho, M. Brasseur, and S. L. McKnight, Science 265:1701-1706, 1994), while the murine Stat6 amino acid and nucleotide sequences were 83 and 84% identical to the human sequences, respectively. Using Stat6-specific antiserum, we demonstrated that Stat6 is rapidly tyrosine phosphorylated following stimulation of appropriate cell lines with IL-4 or IL-3 but is not detectably phosphorylated following stimulation with IL-2, IL-12, or erythropoietin. In contrast, IL-2, IL-3, and erythropoietin induce the tyrosine phosphorylation of Stat5 while IL-12 uniquely induces the tyrosine phosphorylation of Stat4. Inducible tyrosine phosphorylation of Stat6 requires the membrane-distal region of the IL-4 receptor alpha chain. This region of the receptor is not required for cell growth, demonstrating that Stat6 tyrosine phosphorylation does not contribute to mitogenesis.

Amino Acid Sequence↗
PubMed1995

Identification of malignant cells in multiple myeloma bone marrow with immunoglobulin VH gene probes by fluorescent in situ hybridization and flow cytometry.

Because it has been difficult to identify and separate malignant cells in human lymphoid malignancies, we have developed a flow cytometry-based fluorescent in situ hybridization (FISH) technique using immunoglobulin (Ig) heavy chain variable region (VH) gene probes. After obtaining the specific VH gene sequence expressed by the multiple myeloma IM-9 cell line and the malignant cells in five multiple myeloma patients, sense and antisense biotinylated single-stranded RNA probes were prepared by transcription from the malignant clone's VH DNA sequences. The cells from the IM-9 cell line and from the mononuclear bone marrow cells of multiple myeloma patients were fixed, hybridized with the above biotinylated RNA probes, incubated with streptavidin-phycoerythrin, and analyzed by FACS analysis. The myeloma cells stained positive with their own specific antisense VH biotinylated RNa probes, whereas sense and irrelevant antisense biotinylated probes demonstrated only background staining. Dilutional concentrations of the IM-9 cell line with normal bone marrow cells were also accurately quantitated by this procedure. The application of this technique will allow a more accurate assessment of tumor burden in patients with multiple myeloma and should permit an accurate method of tumor cell purification for clinical as well as biological studies. Furthermore, this technological advance should be equally effective at identifying specific VH gene-expressing cells in other lymphoid malignancies, as well as in nonmalignant B cell disorders.

Bacterial Proteins↗