Biomedical subjects
Publications and source records attributed to S Lee.
Models of transplantation of the heart and lung in the rat have been important in determining the mechanisms of rejection and their treatment. Reviewed here are several important milestones contributing to the current state of the art of clinical heart and lung transplantation.
Previous studies have suggested that hepatic arterial flow in heterotopic partial liver transplants is necessary to ensure graft survival and regenerative capacity. This report presents findings in a syngeneic rat strain (Lewis) that partial liver transplants can be successfully heterotopically transplanted in the long term with the only inflow coming from the portal vein. When the host liver undergoes a nearly complete resection at 3-4 weeks, the transplanted liver regenerates to maintain the health of the host. Moderate to massive hepatocellular necrosis occurs in the first 3 months postoperatively, with recovery by 4-5 months. Liver transplants 8-10 months postoperatively appear architecturally normal. No host liver tissues were found to be regenerating after subtotal host liver resection. We conclude that portal vein reconstruction without hepatic arterial inflow can sustain a partial liver transplant in the long term, replacing the function of the host liver.
This periodic report includes intermittent results of consecutive pancreaticoduodenal (Pd) and kidney (Kt) transplants in inbred rats and results on double kidney transplants that did not follow sequential transplant protocol. Eight 24-month-old Lewis pancreas, kidney, and aorta served histological controls showing normal histological architecture with no atherosclerosis developed in the aorta. Thirty-four month old pancreas and thirty-two month old kidneys, which resided in young hosts for at least three occasions, appeared as youthful Pd and Kt grafts. They show normal histological appearance for more than the expected life span of a Lewis rat. The fact that not only pancreases but also kidneys outlived their host leads to the study of other different organs' viability as aged valuable grafts. Nevertheless, the threats by the development of atherosclerosis in graft-associated aortas resulted in slow progression of the follow-ups.
The aim of our study was to examine the effect of labor and birth canal compression on the rate of clearance of lung fluid. We recruited 10 babies born by vaginal delivery and 10 born by elective cesarean section (ECS). Thoracic gas volume (TGV) was measured using total body plethysmography, and functional residual capacity (FRC) by argon dilution, at ages 4-6 h and 24 h. Additional measurements were obtained at age 48 h in the infants born by ECS. Our results showed significant increases in mean TGV (from 23.1 mL/kg to 27.4 mL/kg, P = 0.002) and FRC (from 21.2 mL/kg to 24.1 mL/kg, P = 0.04) between 4-6 h and 24 h of age after ECS delivery. Lung volumes did not change significantly over the next 24 h (TGV, 27.4 mL/kg, P = 0.97; FRC, 25.5 mL/kg, P = 0.42). In those infants born by vaginal delivery, the mean TGV at 4-6 h and 24 h were 26.7 and 28.7 mL/kg, respectively (P = 0.09), and the mean FRC results were 23.1 and 24.9 mL/kg, respectively, P = 0.08). The TGV tended to be lower at 4-6 h in those born by ECS than in infants born vaginally (23.1 vs. 26.7 mL/kg, P = 0.05). We conclude that there is a delay of up to 24 h in the establishment of final lung volumes in babies born without exposure to labor or passage through the birth canal, and that this may explain the increased respiratory morbidity associated with delivery by ECS.
Clinical observations suggest that eradication of the hepatitis B virus (HBV) is immune-mediated. Vigorous cytotoxic T lymphocyte (CTL) activity directed at HLA class I-bound viral epitopes are detected during acute hepatitis B, but not in chronic hepatitis B carriers. A CTL epitope derived from the hepatitis B core protein amino acids 18-27 has been incorporated into a vaccine also comprised of a T-helper cell epitope and 2 palmitic acid residues (CY-1899). The aim of this study was to determine whether repeated doses of CY-1899 given to patients with chronic hepatitis B could initiate in vivo CTL activity and viral clearance. Patients with chronic hepatitis B received up to 4 doses (ranging from 0.05 mg to 15 mg) 6 weeks apart. Following vaccination, patients were monitored for hepatitis B surface antigen and "e" status, HBV-DNA levels, liver biochemistry, CTL activity, and any adverse events. Ninety patients with chronic hepatitis B infection received CY-1899. Mean CTL responses were all low but were maximal following vaccination with 5 mg CY-1899. Peak CTL responses never exceeded 10 lytic units (LU) regardless of vaccine dose, this value being well below that seen following resolution of acute hepatitis B. No significant changes in liver biochemistry or viral serology were observed during follow-up. No serious adverse events were noted. Administration of the single-epitope vaccine, CY-1899, initiated CTL activity, but of a magnitude lower than that observed during spontaneous HBV clearance. This low-level CTL activity was not associated with viral clearance.
We have explored the possibility of using avian cells for the expression of human proteins. We found that various avian cells including quail fibrosarcoma cells (QF), duck embryo cells (DE) and primary chicken embryo fibroblasts (CE) could efficiently be transfected with DNA by calcium phosphate coprecipitation, and that promoters which are transcriptionally active in mammalian cells also functioned well in these avian cells. Among the promoters we tested, the major immediate early promoter of human cytomegalovirus drove the highest level of chloramphenicol acetyl transferase (CAT) expression, outperforming the SV40 early promoter and the RSV LTR. Using the bacterial CAT gene as a reporter, we found that levels of CAT activity were higher in QF and DE cells than in mammalian cells such as CHO, HeLa, Vero and 293T cells. We further cloned a sequence encoding human erythropoietin (EPO) and compared its expression in QF and mammalian cells. Consistent with the CAT data, in transient transfection assays, QF cells produced higher levels of EPO than the mammalian cell lines tested. QF cells which can be passaged permanently were stably transfected with an EPO expression vector. The subcloned QF line was able to produce up to 1,700 U/ml EPO from 3 x 10(6) cells in 72 h. Purified QF-produced EPO showed a broad but discrete protein band, ranging from 33 to 41 kD and was as biologically active as CHO-produced EPO. Although a number of factors still remain to be optimized, our results demonstrate the potential of avian cells such as QF as producers of heterologous proteins.
The products of the Ha-, Ki-, and N-ras proto-oncogenes comprise a family of 21 kDa guanine nucleotide-binding proteins which play a crucial role in growth factor signal transduction and in the control of cellular proliferation and differentiation. Activating mutations in the ras oncogenes occur in a wide variety of human tumors. Ras proteins undergo a series of posttranslational processing events. The first modification is addition of the 15-carbon isoprene, farnesyl, to a Cys residue near the carboxy-terminus of Ras. Prenylation allows the Ras oncoprotein to localize to the plasma membrane where it can initiate downstream signalling events leading to cellular transformation. Inhibitors of the enzyme which catalyzes this step, farnesyl protein transferase (FPT), are a potential class of novel anticancer drugs which interfere with Ras function. SCH 59228 is a tricyclic FPT inhibitor which inhibits the farnesylation of purified Ha-Ras with an IC50 of 95 nM and blocks the processing of Ha-Ras in Cos cells with an IC50 of 0.6 microM. SCH 59228 has favorable pharmacokinetic properties upon oral dosing in nude mice. The in vivo efficacy of SCH 59228 was evaluated using a panel of tumor models grown in nude mice. These included several rodent fibroblast lines expressing mutationally-activated (val12) forms of the Ha-Ras oncogene. In some cases, these proteins contain their native C-terminal sequence (CVLS) which directs farnesylation. In one model, the C-terminal sequence was altered to CVLL, making the expressed protein a substrate for a distinct prenyl transferase, geranylgeranyl protein transferase-1. When dosed orally at 10 and 50 mg/kg (four times a day, 7 days a week) SCH 59228 significantly inhibited tumor growth of cells expressing farnesylated Ha-Ras in a dose-dependent manner; over 90% growth inhibition was observed at the 50 mg/kg dose. Tumor growth of cells expressing the geranylgeranylated form of Ha-Ras was less potently inhibited. Growth of tumors derived from a rodent fibroblast line expressing activated Ki-Ras containing its native C-terminal sequence (CVIM), which preferentially directs farnesylation, was also inhibited by SCH 59228. Inhibition in the Ki-Ras model was less than that observed in the Ha-Ras model. In contrast, tumors derived from cells transformed with the mos oncogene were not significantly inhibited even at the highest dose level. SCH 59228 also significantly and dose-dependently inhibited the growth of human colon adenocarcinoma DLD-1 xenografts (which express activated Ki-ras). These results indicate that SCH 59228 possesses in vivo antitumor activity upon oral dosing in tumor models expressing activated ras oncogenes. This is the first report of oral antitumor activity with an FPT inhibitor. These results are discussed in light of recent observations on alternative prenylation of some Ras isoforms.
RNA-dependent RNA polymerase (RDRP) activity was identified in lysates of Eimeria maxima sporozoites and E. necatrix sporozoites and merozoites. Pretreatment of cell lysates with DNase I, RNase A, proteinase K and actinomycin D prior to RDRP assay was employed to characterize RDRP activity. DNase I and actinomycin D had little effect, while proteinase K abolished RDRP activity in both species. RNase A at a concentration of 1 mg/ml also reduced the polymerase activity in E. maxima and E. necatrix sporozoite lysates to 2% and 0%, respectively. Gel electrophoresis of RDRP products revealed that while most migrated at sizes less than 3 kb, a proportion of labelled products of E. necatrix and E. maxima also migrated to the sizes of their respective putative viral genomes. The RDRP products of E. necatrix were shown to be single-stranded by digestion with RNase in both low- and high-salt solutions and by methylmercuric hydroxide treatment. Moreover, the RDRP products of E. necatrix only hybridized to the 5.6-kb dsRNA of E. necatrix but not to the 4.5-kb dsRNAs of E. necatrix or E. maxima.
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PURPOSE: Depression is a highly prevalent, morbid, and costly illness that is often unrecognized and inadequately treated. Because depression questionnaires have the potential to improve recognition, we evaluated the accuracy and effects on primary care of two case-finding instruments compared to usual care. SUBJECTS AND METHODS: The study was conducted at three university-affiliated and one community-based medical clinics. Consecutive patients were randomly assigned to be asked a single question about mood, to fill out the 20-item Center for Epidemiologic Studies Depression Screen, or to usual care. Within 72 hours, patients were assessed for Diagnostic and Statistical Manual of Mental Disorders Third Revised Edition (DSM-III-R) disorders by an assessor blinded to the screening results. Process of care was assessed using chart audit and administrative databases; patient and physician satisfaction was assessed using Likert scales. At 3 months, depressed patients and a random sample of nondepressed patients were re-assessed for DSM-III-R disorders and symptom counts. RESULTS: We approached 1,083 patients, of whom 969 consented to screening and were assigned to the single question (n = 330), 20-item questionnaire (n = 323), or usual care (n = 316). The interview for DSM-III-R diagnosis was completed in 863 (89%) patients; major depression, dysthymia, or minor depression was present in 13%. Both instruments were sensitive, but the 20-item questionnaire was more specific than the single question (75% vs 66%, P = 0.03). The 20-item questionnaire was less likely to be self-administered (54% vs 90%) and took significantly more time to complete (15 vs 248 seconds). Case-finding with the 20-item questionnaire or single question modestly increased depression recognition, 30/77 (39%) compared with 11/38 (29%) in usual care (P = 0.31) but did not affect treatment (45% vs 43%, P = 0.88). Effects on DSM-III-R symptoms were mixed. Recovery from depression was more likely in the case-finding than usual care groups, 32/67 (48%) versus 8/30 (27%, P = 0.03), but the mean improvement in depression symptoms did not differ significantly (1.6 vs 1.5 symptoms, P = 0.21). CONCLUSIONS: A simple question about depression has similar performance characteristics as a longer 20-item questionnaire and is more feasible because of its brevity. Case-finding leads to a modest increase in recognition rates, but does not have consistently positive effects on patient outcomes.
OBJECTIVE: Maternal vaccination may become a central strategy in the prevention of early-onset group B Streptococcal sepsis. Unlike earlier group B streptococcal polysaccharide vaccines that were poorly immunogenic, newer vaccines conjugated to tetanus toxoid have been developed and have improved immunogenicity. We sought to evaluate a conjugated vaccine using our rabbit model of ascending infection. STUDY DESIGN: Rabbit does were randomized to receive either conjugated group B streptococcal type Ia (Ia-tetanus toxoid) or conjugated group B streptococcal type III (III-tetanus toxoid) vaccine. Does were vaccinated 7 days before conception and 7 and 21 days after conception. On days 28 to 30 of a 30-day gestation, does were inoculated intracervically with 10(6) colony-forming units of type Ia group B Streptococcus. Labor was induced if does were undelivered after 72 hours. Does were observed up to 7 days after inoculation. Offspring were observed up to 4 days. We obtained maternal cultures from the uterus, peritoneum, and blood and offspring cultures from the mouth, anus, and blood. Antibody levels were also determined. RESULTS: Offspring survival was significantly improved in the group receiving Ia-tetanus toxoid (P =.047). Outcomes such as maternal sepsis and severe illness, although not reaching statistical significance, showed a trend toward improved outcomes in the Ia-tetanus toxoid group. CONCLUSIONS: This is the first study to evaluate the conjugated group B streptococcal vaccine by using any model of ascending infection. The Ia-tetanus toxoid vaccine led to improved survival and was immunogenic but fell short of its expected efficacy in preventing ascending group B streptococcal disease under these experimental conditions.
Lipid-peptide interaction has been investigated using cationic amphiphilic alpha-helical peptides and systematically varying their hydrophobic-hydrophilic balance (HHB). The influence of the peptides on neutral and acidic liposomes was examined by 1) Trp fluorescence quenched by brominated phospholipid, 2) membrane-clearing ability, 3) size determination of liposomes by dynamic light scattering, 4) morphological observation by electron microscopy, and 5) ability to form planar lipid bilayers from channels. The peptides examined consist of hydrophobic Leu and hydrophilic Lys residues with ratios 13:5, 11:7, 9:9, 7:11, and 5:13 (abbreviated as Hels 13-5, 11-7, 9-9, 7-11, and 5-13, respectively; Kiyota, T., S. Lee, and G. Sugihara. 1996. Biochemistry. 35:13196-13204). The most hydrophobic peptide (Hel 13-5) induced a twisted ribbon-like fibril structure for egg PC liposomes. In a 3/1 (egg PC/egg PG) lipid mixture, Hel 13-5 addition caused fusion of the liposomes. Hel 13-5 formed ion channels in neutral lipid bilayer (egg PE/egg PC = 7/3) at low peptide concentrations, but not in an acidic bilayer (egg PE/brain PS = 7/3). The peptides with hydrophobicity less than Hel 13-5 (Hels 11-7 and Hel 9-9) were able to partially immerse their hydrophobic part of the amphiphilic helix in lipid bilayers and fragment liposome to small bicelles or micelles, and then the bicelles aggregated to form a larger assembly. Peptides Hel 11-7 and Hel 9-9 each formed strong ion channels. Peptides (Hel 7-11 and Hel 5-13) with a more hydrophilic HHB interacted with an acidic lipid bilayer by charge interaction, in which the former immerses the hydrophobic part in lipid bilayer, and the latter did not immerse, and formed large assemblies by aggregation of original liposomes. The present study clearly showed that hydrophobic-hydrophilic balance of a peptide is a crucial factor in understanding lipid-peptide interactions.
STATEMENT OF PROBLEM: Accuracy of techniques for recording the orientation of the maxillary arch to the articulation of the temporomandibular joints has been reported. The variability contributed by the dentist and the equipment within a technique may also contribute to technical error. PURPOSE: This study investigated the variability of a group of dentists who used an arbitrary ear-face-bow instrument to mount a maxillary cast. MATERIAL AND METHODS: The same maxillary cast on a single experimental subject was mounted on an articulator with a common arbitrary ear-face-bow instrument. This cast was equipped with 4 reference points for the measurement of changes of spatial orientation of the cast, which were determined through coordinate measurements with a machinist's microscope. A repeated measures analysis of variance was used to determine statistically significant changes in spatial orientation with a Wilks' Lambda test to compare mean values. RESULTS: A confidence interval of 95% demonstrated that any dentist might expect a range of +/-1.2 mm error in using this instrument/articulator combination. The 3 dentists did not demonstrate any significant differences in the spatial orientation of their mountings in the vertical or horizontal directions. However, there were significant differences in their mountings in linear distance changes of the patient's posterior right side. CONCLUSION: A range of inherent error attributable to the operator using this instrument was recorded.
BACKGROUND: Studies on the relation between insight and medication adherence are limited in Chinese populations. METHOD: Eighty Chinese outpatients with mood disorder and on lithium for at least one year were asked to complete an 11-item insight scale. Lithium adherence was determined by: (a) subjective report; (b) doctor's clinical impression; or (c) serum lithium level. RESULTS: The overall insight score (median = 9, range 1-11) exhibited no significant difference between adherent (N = 58, 72.5%) and non-adherent (N = 22, 27.5%) patients. A two-factor model emerged on factor analysis. Lithium adherent (median = 7, range 1-7) patients had a significantly higher score than non-adherent (median = 6, range 0-7) patients on the 'medical help seeking' factor (Mann-Whitney U-test Z = 2.00, P < 0.05) but not the 'perception of illness' factor. CONCLUSION: The overall conceptual structure of insight in Chinese and Western patients appears similar, but further study is required to explore the complexity of Chinese patients' explanatory models of their illness and to enhance the validity of the insight scale.
The injection of allogeneic cells via the portal vein (p.v.) is known to reduce responses to donor-alloantigens. In the present study, we have obtained persistent tolerance across Mls and multiple minor histocompatibility complexes by p.v. preimmunization followed by the administration of cyclophosphamide (CY). A hundred percent survival of (BALB/c x DBA/2)F1 (CDF1) skin grafts for more than 200 days was observed when BALB/c mice were preimmunized with spleen cells of CDF1 (3 x 10(7)) via the p.v. and administered 300 mg/Kg CY 2 days after the p.v. injection. Comparable survival of the skin graft was observed when bone marrow cells instead of spleen cells were p.v. preimmunized. However, the survival rate was significantly decreased when LPS-stimulated blastic cells were p.v. preimmunized. Microchimerism has been observed in the liver, thymus, bone marrow and peripheral blood of recipients. V beta 6+ cells decreased in CD4+ cells of recipients of the p.v. preimmunization plus CY treatment. However, there was no difference in the decrease in V beta 6+ cells between recipients accepting the CDF1 skin grafts and recipients that had rejected the skin grafts. Furthermore, no intrathymic depletion of the V beta 6+ cells was observed. From these results, it is suggested that, rather than clonal deletion, other mechanisms such as clonal anergy or suppression may be involved in the induction of persistent tolerance after the p.v. preimmunization plus CY treatment.
Human spondyloarthropathies are strongly associated with a major histocompatibility complex (MHC) class I allele, HLA-B27. HLA-B27 transgenic mice and rats demonstrate many features of these diseases further confirming the role of HLA-B27 in disease. Yet the exact role of this molecule in disease pathogenesis is not clearly understood. We have previously reported spontaneous arthritis and nail disease in HLA-B27 transgenic mice lacking beta2-microglobulin (B27+beta2m(o)). These observations along with binding studies of B27 derived peptides to HLA-B27 molecule itself led to two hypotheses: (i) HLA-B27 derived peptide as a source of autoantigen; and (ii) HLA-B27 functions as an antigen presenting molecule. In this report, we confirm spontaneous disease in transgenic mice expressing a hybrid B27 molecule with alpha1alpha2 domain of B27 and alpha3 domain of mouse H-2Kd. These mice developed spontaneous arthritis and nail disease when transferred from specific pathogen free barrier facility to the conventional area. Other control mice with MHC class I transgene (e.g., HLA-B7, HLA-Cw3, and H2-Dd) did not develop such disease. In a MHC reassembly assay, binding of similar peptides to both wild type and hybrid B27 molecules was observed. In addition, the hybrid B27 molecule lacks at least one of the 3 proposed peptides from the third hypervariable (HV3) region of HLA-B27. These data strongly suggest that HLA-B27 molecule is an antigen presenting molecule rather than a peptide donor in the disease pathogenesis.
BACKGROUND: The human foot is often modelled as a rigid body in gait analysis. A more realistic model separates this segment into a forefoot and rearfoot. However, no three-dimensional data has been published on dynamic relative ab-adduction between these segments, and how this impacts changes in foot shape. OBJECTIVE: The purpose was to quantify three-dimensionally forefoot ab-adduction relative to the rearfoot in vitro, and to determine how forefoot ab-adduction affects foot length. METHODS: Video data were collected from reflective marker triads affixed to the ends of Steinmann pins drilled into the tibia, calcaneus, cuboid, and the first and fifth metatarsal bones. Medial and lateral foot length and forefoot ab-adduction relative to the rearfoot were calculated under two axial tibial loads (200 N, 600 N) and two input motions (dorsi-plantarflexion, internal-external tibial rotation). RESULTS: It was found that patterns of change for each variable were dependent on the degree of rigidity of the foot. Relative forefoot ab-adduction values ranged from 4.4 degrees of adduction to 1.7 degrees of abduction. Medial foot length values changed +/- 0.8 mm (+/- 0.5%) and lateral foot length values changed +/- 0.5 mm (+/- 0.3%). Medial foot length was correlated positively with relative forefoot abduction, and external tibial rotation was correlated positively with relative forefoot adduction.
The effect of the neurosteroid dehydroepiandrosterone sulfate on inhibitory synaptic transmission was studied in area CA1 of the rat hippocampus using an in vitro hippocampal slice preparation. Synaptic responses elicited by stimulation of Schaffer collateral fibers were recorded extracellularly as population spikes in the somatic region and as synaptic field potentials in the dendritic region. Bath application of dehydroepiandrosterone sulfate (10 microM) enhanced the synaptically evoked somatic population spike with no effect on the dendritic synaptic potential. Isolation of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor-mediated component of the synaptic response by addition of antagonists of N-methyl-D-aspartate and GABA receptors to the perfusion saline demonstrated that dehydroepiandrosterone sulfate had no effect on this component of the dendritic synaptic potential. In contrast, dehydroepiandrosterone sulfate antagonized GABA receptor-mediated inhibitory effects in the somatic region, resulting in an augmentation of the somatic population spike amplitude. Paired-pulse facilitation was unaltered by dehydroepiandrosterone sulfate, thus arguing against possible presynaptic sites of dehydroepiandrosterone sulfate's actions. These results indicate that dehydroepiandrosterone sulfate can alter synaptic transmission in the hippocampus through selective postsynaptic actions on inhibitory synaptic transmission. A synaptic effect of dehydroepiandrosterone sulfate is consistent with a neuromodulatory role for this neurosteroid in the central nervous system, and may contribute to the reported effects of dehydroepiandrosterone sulfate on cognitive processes such as learning and memory.