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Biomedical subjects

D M Lee

Publications and source records attributed to D M Lee.

At least 19 recordsLinked to original sources
PubMed2000

Linkage of the CCR5 Delta 32 mutation with a functional polymorphism of CD45RA.

A 32-bp deletion in CCR5 (CCR5 Delta 32) confers to PBMC resistance to HIV-1 isolates that use CCR5 as a coreceptor. To study this mutation in T cell development, we have screened 571 human thymus tissues for the mutation. We identified 72 thymuses (12.6%) that were heterozygous and 2 (0.35%) that were homozygous for the CCR5 Delta 32 mutation. We found that thymocyte development was normal in both CCR5 Delta 32 heterozygous and homozygous thymuses. In 3% of thymuses we identified a functional polymorphism of CD45RA, in which cortical and medullary thymocytes failed to down-regulate the 200- and 220-kDa CD45RA isoforms during T cell development. Moreover, we found an association of this CD45 functional polymorphism in thymuses with the CCR5 Delta 32 mutation (p = 0.00258). In vitro HIV-1 infection assays with CCR5-using primary isolates demonstrated that thymocytes with the heterozygous CCR5 Delta 32 mutation produced less p24 than did CCR5 wild-type thymocytes. However, the functional CD45RA polymorphism did not alter the susceptibility of thymocytes to HIV-1 infection. Taken together, these data demonstrate association of the CCR5 Delta 32 mutation with a polymorphism in an as yet unknown gene that is responsible for the ability to down-regulate the expression of high m.w. CD45RA isoforms. Although the presence of the CCR5 Delta 32 mutation down-regulates HIV-1 infection of thymocytes, the functional CD45RA polymorphism does not alter the susceptibility of thymocytes to HIV-1 infection in vitro.

Adolescent↗
PubMed2000

Regulation of force and unloaded sliding speed in single thin filaments: effects of regulatory proteins and calcium.

1. Measurements of the unloaded sliding speed of and isometric force exerted on single thin filaments in in vitro motility assays were made to evaluate the role of regulatory proteins in the control of unloaded thin filament sliding speed and isometric force production. 2. Regulated actin filaments were reconstituted from rabbit F-actin, native bovine cardiac tropomyosin (nTm), and either native bovine cardiac troponin (nTn), troponin containing a TnC mutant, CBMII, in which the sole regulatory site in cardiac TnC (site II) is inactivated (CBMII-Tn), or troponin containing a point mutation in TnT (I79N, where isoleucine at position 79 is replaced with asparagine) associated with familial hypertrophic cardiomyopathy (FHC). 3. Addition of regulatory proteins to the thin filament increases both the unloaded sliding speed and the isometric force exerted by myosin heads on the thin filaments. 4. Variation of thin filament activation by varying [Ca2+] or the fraction of CBMII/TnC bound to the thin filament at pCa 5, had little effect on the unloaded filament sliding speed until the fraction of the thin filament containing calcium bound to TnC was less than 0.15. These results suggest that [Ca2+] primarily affects the number of attached and cycling crossbridges. 5. The presence of the FHC TnT mutant increased the thin filament sliding speed but reduced the isometric force that heavy meromyosin exerted on regulated thin filaments. These latter results, together with the increased sliding speed and isometric force seen in the presence of regulatory proteins, suggest that thin filament regulatory proteins exert significant allosteric effects on the interaction of crossbridges with the thin filament.

Actins↗
PubMed2000

An analysis of drug interaction between morphine and neostigmine in rats with nerve-ligation injury.

UNLABELLED: Intrathecal neostigmine reverses mechanical allodynia in humans and animals. The efficacy of morphine in a neuropathic pain state is still controversial. This study examines the antiallodynic interaction between morphine and neostigmine in a rat model of neuropathic pain. Rats were prepared with tight ligation of left L5-6 (fifth and sixth lumbar) spinal nerves and chronic intrathecal catheter implantation. Mechanical allodynia was measured by using application of von Frey hairs to the left hindpaw. Morphine (1, 3, 10, and 30 microg) and neostigmine (0.3, 1, 3, and 10 microg) were administered intrathecally to obtain the dose-response curves and the 50% effective dose (ED(50)) for each drug. ED(50) values and fractions of the ED(50) values (1/2, 1/4, and 1/8) were administered intrathecally in an equal dose ratio to establish the ED(50). Isobolographic and fractional analyses for the drug interaction were performed. Intrathecal morphine produced a moderate antagonism of the tactile allodynia. A morphine-neostigmine combination produced a dose-dependent increase in withdrawal threshold of the lesioned hind paw with reduced side effects. Both analyses revealed a synergistic interaction after the coadministration of morphine and neostigmine. These experiments suggest that the antiallodynic action of a morphine-neostigmine combination is synergistic at the spinal level. IMPLICATIONS: This study indicates that, by using both isobolographic and fractional analyses, the antiallodynic effect of intrathecal morphine and neostigmine is synergistic when coadministered intrathecally. In a rat model of neuropathic pain, the intrathecal morphine produced a moderate antagonism on touch-evoked allodynia at the spinal level.

Analgesics, Opioid↗
PubMed2000

Adult T cell leukemia/lymphoma with lymphopenia in a Korean.

We experienced a case of adult T cell leukemia/lymphoma (ATLL) in a 48-year-old Korean female, who has never been abroad since birth and no history of blood transfusion. The patient had hypercalcemia and multiple lymphadenopathy. Histopathologic study of left cervical lymph node (LN) and bone marrow (BM) revealed that infiltrates of malignant lymphoid cells were composed of small, medium and large cells with pleomorphic nuclei. Smears of peripheral blood (PB) showed lymphopenia (16%) with the appearance of a few atypical lymphoid cells (less than 2%), but not the typical clover leaf cells seen in ATLL. Immunophenotypic study of LN and BM revealed T cell phenotype. PB showed increased CD4+ T cell (T(H), CD3/CD4+, 57%) and decreased CD8+ T cell counts (T(S), CD3/CD8+, 6.7%). The sera of the patient and her family were reactive for HTLV-I antibody. The specific sequences of pol, env, and tax of HTLV-I DNA were detected in the lymphoma cells and peripheral blood mononuclear cells (PBMC) using polymerase chain reaction. Ultrastructural examination of PBMC confirmed numerous type c virus particles in extracellular space. This case was an acute type of ATLL without overt leukemic features in PB. Despite chemotherapy and intensive conservative treatment, she died 3 months after admission.

Biopsy↗
PubMed2000

Altered immune responses in apolipoprotein E-deficient mice.

Apolipoprotein E (apoE) is a 34 kDa glycosylated protein with multiple biological properties. In addition to its role in cholesterol transport, apoE has in vitro immunomodulatory properties. Recent data suggest that these immunomodulatory effects of apoE may be biologically relevant, and apoE-deficient mice have altered immune responses after bacterial inoculation and increased susceptibility to endotoxemia induced by lipopolysaccharide (LPS). To better understand the mechanism by which apoE-modulates immune responses, we tested the role of human apoE isoforms in assays of human T cell proliferation, and analyzed the immune responses of apoE-deficient mice. Both the E3 and E4 isoforms of apoE induced similar suppression of human lymphocyte function in assays of T cell proliferation, including mitogenic responses to phytohaemagglutin (PHA), stimulation of the T cell receptor with alphaCD3, and antigen-specific response to tetanus toxoid. ApoE-deficient mice showed no quantitative differences in thymic, splenic, or bone marrow lymphocyte populations, nor were there in vitro abnormalities in splenocyte proliferation after stimulation with alphaCD3 to suggest an inherent T cell defect in apoE-deficient mice. ApoE deficient animals, however, had significantly higher levels of antigen-specific IgM after immunization with tetanus toxoid, and impaired delayed type hypersensitivity responses as compared to control C57-BL/6 mice. These results support a growing body of evidence demonstrating an interplay between lipid metabolism and immune responses, and suggest that apoE plays a biologically relevant role in regulating humoral and cell-mediated immunity.

Adjuvants, Immunologic↗
PubMed1999

Resistance of CD7-deficient mice to lipopolysaccharide-induced shock syndromes.

CD7 is an immunoglobulin superfamily molecule involved in T and natural killer (NK) cell activation and cytokine production. CD7-deficient animals develop normally but have antigen-specific defects in interferon (IFN)-gamma production and CD8(+) CTL generation. To determine the in vivo role of CD7 in systems dependent on IFN-gamma, the response of CD7-deficient mice to lipopolysaccharide (LPS)-induced shock syndromes was studied. In the high-dose LPS-induced shock model, 67% of CD7-deficient mice survived LPS injection, whereas 19% of control C57BL/6 mice survived LPS challenge (P < 0.001). CD7-deficient or C57BL/6 control mice were next injected with low-dose LPS (1 microgram plus 8 mg D-galactosamine [D-gal] per mouse) and monitored for survival. All CD7-deficient mice were alive 72 h after injection of LPS compared with 20% of C57BL/6 control mice (P < 0.001). After injection of LPS and D-gal, CD7-deficient mice had decreased serum IFN-gamma and tumor necrosis factor (TNF)-alpha levels compared with control C57BL/6 mice (P < 0.001). Steady-state mRNA levels for IFN-gamma and TNF-alpha in liver tissue were also significantly decreased in CD7-deficient mice compared with controls (P < 0.05). In contrast, CD7-deficient animals had normal liver interleukin (IL)-12, IL-18, and interleukin 1 converting enzyme (ICE) mRNA levels, and CD7-deficient splenocytes had normal IFN-gamma responses when stimulated with IL-12 and IL-18 in vitro. NK1.1(+)/ CD3(+) T cells are known to be key effector cells in the pathogenesis of toxic shock. Phenotypic analysis of liver mononuclear cells revealed that CD7-deficient mice had fewer numbers of liver NK1.1(+)/CD3(+) T cells (1.5 +/- 0.3 x 10(5)) versus C57BL/6 control mice (3.7 +/- 0.8 x 10(5); P < 0.05), whereas numbers of liver NK1.1(+)/CD3(-) NK cells were not different from controls. Thus, targeted disruption of CD7 leads to a selective deficiency of liver NK1.1(+)/ CD3(+) T cells, and is associated with resistance to LPS shock. These data suggest that CD7 is a key molecule in the inflammatory response leading to LPS-induced shock.

Animals↗
PubMed1999

A simple and sensitive method in using the ratios of cholesteryl ester molecular species as indexes of oxidative stress in plasma and lipoprotein fractions.

To develop a simpler method for lipid peroxidation which may replace the classic gold standard of measuring the loss of polyunsaturated fatty acids, we investigated the use of ratios of molecular species of neutral lipids (MSNL) separated by gas chromatography in a single step. We sub-fractionated lipoproteins and subjected each to oxidation. Among different combinations of ratios of MSNL, we found that the ratios of cholesteryl esters (CE) containing C20/C16 (R1) and C18/C16 (R2) decreased most rapidly with increasing Cu2+ concentration and with increasing oxidation time, for all lipoproteins. We suggest that these two CE ratios can be used as oxidative indexes for all lipoproteins and thus for intact plasma. Experimental evidence showed that the oxidative index of whole plasma is the weighted average index of its lipoproteins. This method was validated with thiobarbituric acid method. Normal healthy asymptomatic males had R1 value 0.496 +/- 0.130, and R2 4.674 +/- 0.848, and females had R1 0.535 +/- 0.117 and R2 4.569 +/- 0.733 with no significant gender differences. Both ratios showed low variabilities within each individual. The method was tested to be feasible in monitoring vitamin E supplementation study. This CE-ratio method is concentration independent. It is simple, rapid, and highly reproducible, and, suitable for screening plasma on large scale.

Cholesterol Esters↗
PubMed1999

Formal teaching of surgical skills in an obstetric-gynecologic residency.

OBJECTIVE: To describe a formal teaching program of basic surgical skills in an obstetric-gynecologic residency program and evaluate its effectiveness. METHODS: A surgical skills program was developed for all residents. Using bench and animal laboratory sessions, residents were given instruction and performed both laparoscopic and open abdominal procedures. All were given a pretest and were tested again 6 months later. Residents also evaluated their experiences. RESULTS: To date, the formal teaching sessions have been given to 24 residents, all of whom believed their confidence and technical skills improved as a result of the sessions. On a scale of 1 to 5, the median rating of the bench laboratory experience was 5 (range 4-5), and the pig laboratory was 5 (range 4-5). All residents believed the surgery sessions should be continued and the number of sessions increased. Preliminary evaluation indicated that time to suture a 10-inch incision decreased by 28%, from an average of 225 (standard deviation [SD] 51) seconds to 171 (SD 43) seconds (P < .001), and evaluation of surgical technique significantly improved at the second pretest (P = .013). Laparoscopic placement of pegs on a board in 2 minutes increased from an average of 5 (SD 2.5) to 7.3 (SD 2.6; P = .001). The cost of the bench laboratory sessions was minimal. Each pig was approximately $100, and the facility charge for each 4-hour laboratory session was $1500. CONCLUSION: When formal surgical training was given to obstetric-gynecologic residents, their surgical skills improved subjectively and objectively.

Adult↗
PubMed1999

The antiallodynic effects of intrathecal cholinesterase inhibitors in a rat model of neuropathic pain.

BACKGROUND: This study determined the effect of intrathecally administered cholinesterase inhibitors, edrophonium and neostigmine, on nerve injury-induced, touch-evoked allodynia and identified the pharmacologic characteristics of this action. METHODS: Rats were prepared with tight ligation of the left L5 and L6 spinal nerves and with lumbar intrathecal catheters fitted for long-term monitoring. Edrophonium (3, 10, 30, or 100 microg) or neostigmine (0.3, 1, 3, or 10 microg) was administered intrathecally. Tactile allodynia and motor weakness were assessed. To evaluate the pharmacologic characteristics of the activity, a muscarinic receptor antagonist or a nicotinic receptor antagonist was administered intrathecally before edrophonium or neostigmine was injected. To compare the action of subtype antagonists, the M1 muscarinic receptor antagonist pirenzepine, the M2 antagonist methoctramine, the M3 antagonist 4-DAMP (diphenylacetoxy-N-methypiperidine), and the M4 antagonist tropicamide were administered intrathecally before cholinesterase inhibitors were injected. RESULTS: Intrathecal edrophonium or neostigmine produced a dose-dependent antagonism of the touch-evoked allodynia. Neostigmine resulted in a moderate effect on motor weakness at doses of 3 and 10 microg. Pretreatment with intrathecal atropine but not mecamylamine yielded a complete antagonism of the effects of the cholinesterase inhibitors. In addition, antiallodynia produced by edrophonium (100 microg) was reversed by pretreatment with methoctramine, 4-DAMP, tropicamide, and pirenzepine. In the neostigmine (10 microg) group, only the M1 antagonist pirenzepine had a moderate effect on reversal of increased allodynic threshold. CONCLUSIONS: These experiments suggest that intrathecal edrophonium or neostigmine produces an antagonism on touch-evoked allodynia at the spinal level in a rat model of neuropathic pain and that the antiallodynic action of cholinesterase inhibitors is probably mediated by a spinal muscarinic system, especially at the M1 receptor subtype.

Animals↗
PubMed1999

The plasma levels of homocysteine are elevated in moderate renal insufficiency but do not predict the rate of progression.

BACKGROUND: Chronic renal failure is characterized by specific alterations of the lipoprotein metabolism. It is also characterized by elevated plasma levels of total homocysteine (tHcy). Hyperhomocysteinemia has been shown to be a risk factor for atherosclerosis in both the general population and in patients with end-stage renal disease. AIM: To analyze whether elevated tHcy levels also may contribute to a higher rate of progression of renal insufficiency in patients with moderately advanced renal failure. METHODS: To investigate whether tHcy concentrations are associated with an accelerated rate of progression of renal insufficiency, we have correlated baseline plasma concentrations of tHcy with the progressive decline of renal function in an observational study of human chronic renal disease. RESULTS: Sixty-three nondiabetic patients (49 men, 14 women) were studied as part of an observational study of patients with moderately advanced renal insufficiency. The average follow-up time of the patient population was 3.0 years, and the mean rate of decline in glomerular filtration rate ((51)Cr- EDTA clearance) was -3.2 +/- (SD) 3.9 ml/min x 1.73 m(2) body surface area. The mean plasma concentration of tHcy at the beginning of the study was 28.3 +/- 12.0 micromol/l. Plasma tHcy concentrations correlated significantly with the glomerular filtration rate (r = -0. 32, p < 0.01). However, there was no association between the initial plasma level of tHcy and the rate of progression as assessed by linear regression analysis (r = 0.02; NS). In contrast, increased levels of apolipoprotein B, low-density lipoprotein cholesterol, and proteinuria were all significantly associated with a more rapid decline in renal function. CONCLUSIONS: Patients with moderately advanced chronic renal insufficiency have elevated plasma levels of homocysteine. The tHcy plasma levels increase in parallel with the degree of reduction in renal function. However, the hyperhomocysteinemia is not prospectively associated with a higher rate of progression of the renal functional impairment. Hence, there is no indication that elevated homocysteine levels play a contributing role for an accelerated glomerulosclerotic process.

Adult↗
PubMed1999

Structure and function of the CD7 molecule.

CD7 is a single-domain Ig superfamily molecule expressed on human T and NK cells, as well as on cells in the early stages of T, B, and myeloid cell differentiation. CD7 is highly expressed on malignant immature T cells and is generally absent on malignant mature T cells, such as CD4+ Sezary leukemia and HTLV-1+ adult T-cell leukemia cells. Because of lack of identification of a natural ligand and lack of a monoclonal antibody against murine CD7, the in vivo functions of CD7 have until recently remained obscure. Recent studies in CD7-deficient mice have provided new insights into CD7 function, and demonstrated key roles for CD7 in regulating peripheral T and NK cell cytokine production and sensitivity to LPS-induced shock syndromes. This article reviews recent work on the expression, structure, and function of CD7, and discusses roles the CD7 molecule might play in T and NK cell development and function.

Animals↗
PubMed1999

Disseminated coccidioidomycosis complicated by vasculitis: a cause of fatal subarachnoid hemorrhage in two cases.

We describe two cases of disseminated coccidioidomycosis that were complicated by fatal subarachnoid hemorrhage. In the first case, a left middle cerebral artery aneurysm and long-segment vasculitis occurred. In the second case, MR imaging revealed an enlarging coccidioidal granuloma at the tip of the basilar artery, and the artery subsequently ruptured. Fatal intracranial hemorrhage is a rare complication of disseminated coccidioidomycosis.

Adult↗
PubMed1998

Immunologic characterization of CD7-deficient mice.

Human CD7 is an Ig superfamily molecule that is expressed on mature T and NK lymphocytes. Although in vitro studies have suggested a role for CD7 in lymphoid development and function, the exact function of CD7 in vivo has remained elusive. One patient has been reported with SCID syndrome attributed to CD7 deficiency. To study in vivo functions of CD7, we have generated CD7-deficient mice and assessed their lymphoid development and function. CD7-deficient mice were viable, had normal peripheral blood and spleen lymphocyte numbers, and had normal specific Ab responses with Ag-driven Ig isotype switching. Thymocyte numbers were normal in 4-wk-old, 6-mo-old, and 1-yr-old CD7-deficient mice, but in 3-mo-old CD7-deficient mice, total thymocyte numbers were significantly increased by 60% (p < 0.02) compared with normal age-matched +/+ littermates. CD7-deficient splenocytes proliferated normally in response to various mitogens, including PHA, anti-CD3, Con A, and LPS. While NK cell numbers and cytolytic activity to YAC targets were normal, CD7-deficient mice had lower Ag-induced MHC class I-restricted CTL activity against OVA-transfected target cells than did +/+ control mice. Thus, CD7-deficient mice did not have a SCID syndrome, but rather had transient increases in thymocyte numbers at age 3 mo and altered splenocyte Ag-specific CTL effecter cell activity. These data suggest a role for CD7 in regulating intrathymic T cell development and in mediating CTL effecter function.

Animals↗
PubMed1998

ATP analogs and muscle contraction: mechanics and kinetics of nucleoside triphosphate binding and hydrolysis.

The mechanical behavior of skinned rabbit psoas muscle fiber contractions and in vitro motility of F-actin (Vf) have been examined using ATP, CTP, UTP, or their 2-deoxy forms (collectively designated as nucleotide triphosphates or NTPs) as contractile substrates. Measurements of actin-activated heavy meromyosin (HMM) NTPase, the rates of NTP binding to myosin and actomyosin, NTP-mediated acto-HMM dissociation, and NTP hydrolysis by acto-HMM were made for comparison to the mechanical results. The data suggest a very similar mechanism of acto-HMM NTP hydrolysis. Whereas all NTPs studied support force production and stiffness that vary by a factor 2 or less, the unloaded shortening velocity (Vu) of muscle fibers varies by almost 10-fold. 2-Deoxy ATP (dATP) was unique in that Vu was 30% greater than with ATP. Parallel behavior was observed between Vf and the steady-state maximum actin-activated HMM ATPase rate. Further comparisons suggest that the variation in force correlates with the rate and equilibrium constant for NTP cleavage; the variations in Vu or Vf are related to the rate of cross-bridge dissociation caused by NTP binding or to the rate(s) of product release.

Acid Anhydride Hydrolases↗
PubMed1998

Localization of Bcl-2 in the human fetal müllerian tract.

OBJECTIVE: To determine if apoptosis is involved in development of the human fetal mullerian tract and regression of the uterine septum and to localize Bcl-2. a protein involved with regulating apoptosis. DESIGN: Descriptive controlled study. SETTING: Tertiary academic medical center. PATIENT(S): Eight human fetal uteri from 12 to 21 weeks' gestation. INTERVENTION(S): Immunohistochemistry using a monoclonal antibody for Bcl-2. MAIN OUTCOME MEASURE(S): Immunostaining. RESULTS: Bcl-2 was localized in endometrial cells, tubal muscularis and epithelium, and myometrial edges. It was absent from the septum of 4 uteri. CONCLUSIONS: The presence of Bcl-2 suggests that development of the human fetal müllerian tract involves apoptosis. Bcl-2 may protect the fetal endometrium from apoptosis as it continues to grow. The superior, inferior, and lateral myometrium as well as the tubal epithelium and muscularis also may represent active growth zones that are protected from apoptosis. The notable absence of staining for Bcl-2 in the embryonal uterine septum may indicate lack of protection from apoptosis in this area. This finding supports our hypothesis that apoptosis may be a mechanism by which the uterine septum regresses.

Antibodies, Monoclonal↗
PubMed1998

Keratinocyte growth factor modulates alveolar epithelial cell phenotype in vitro: expression of aquaporin 5.

We investigated the role of keratinocyte growth factor (KGF) in regulation of alveolar epithelial cell (AEC) phenotype in vitro. Effects of KGF on cell morphology, expression of surfactant apoproteins A, B, and C (SP-A, -B, and -C), and expression of aquaporin 5 (AQP5), a water channel present in situ on the apical surface of alveolar type I (AT1) cells but not expressed in alveolar type II (AT2) cells, were evaluated in AECs grown in primary culture. Observations were made on AEC monolayers grown in serum-free medium without KGF (control) or grown continuously in the presence of KGF (10 ng/ml) from either Day 0 (i.e., the time of plating) or Day 4 or 6 through Day 8 in culture. AECs monolayers express AQP5 only on their apical surfaces as determined by cell surface biotinylation studies. Control AECs grown in the absence of KGF through Day 8 express increasing levels of AQP5, consistent with transition toward the AT1 cell phenotype. Exposure of AECs to KGF from Day 0 results in decreased AQP5 expression, retention of a cuboidal morphology, and greater numbers of lamellar bodies relative to control on Day 8 in culture. AECs treated with KGF from Day 4 or 6 exhibit a decrease in AQP5 expression through subsequent days in culture, as well as an increase in expression of surfactant apoproteins. These data, showing that KGF both prevents and reverses the increase in AQP5 (and decrease in surfactant apoprotein) expression that accompanies progression of the AT2 toward the AT1 cell phenotype, support the concepts that transdifferentiation between AT2 and AT1 cell phenotypes is at least partially reversible and that KGF may play a major role in modulating AEC phenotype.

Animals↗