Show them what they can't see! An evaluation of the use of customized 3D printed models in head and neck anatomy

Difficulty in visualizing anatomical structures has been identified as a challenge in anatomy learning and the emergence of three-dimensional printed models (3DPMs) offers a potential solution. This study evaluated the effectiveness of 3DPMs for learning the arterial supply of the head and neck region. One hundred eighty-four undergraduate medical students were randomly assigned to one of four learning modalities including wet specimen, digital model, 3DPM, and textbook image. Posttest scores indicated that all four modalities supported participants' knowledge acquisition, most significantly in the wet specimen group. While the participants rated 3DPMs lower for helping correct identification of structures than wet specimens, they praised 3DPMs for their ability to demonstrate topographical relationships between the arterial supply and adjacent structures. The data further suggested that the biggest limitation of the 3DPMs was their simplicity, thus making it more difficult for users to recognize the equivalent structures on the wet specimens. It was concluded that future designs of 3DPMs will need to consider the balance between the ease of visualization of anatomical structures and the degree of complexity required for successful transfer of learning. Overall, this study presented some conflicting evidence of the favorable outcomes of 3DPMs reported in other similar studies. While effective for anatomy learning as a standalone modality, educators must identify the position 3DPM models hold relative to other modalities in the continuum of undergraduate anatomy education in order to maximize their advantages for students.

Polyethylenimine-based amphiphilic core-shell nanoparticles: study of gene delivery and intracellular trafficking

Amphiphilic core-shell nanoparticle, which is composed of a hydrophobic core and a branched polyethylenimine (PEI) shell, has been designed and synthesized as a novel gene delivery nanocarrier. In our previous study, we demonstrated that the core-shell nanoparticle was not only able to efficiently complex with plasmid DNA (pDNA) and protect it against enzymatic degradation, but also three times less cytotoxic, and threefold more efficient in gene transfection than branched 25 kDa PEI. This paper reports our further studies in the following three aspects: (1) the ability of the PEI-based nanoparticles to deliver gene in various mammalian cell lines; (2) intracellular distributions of the nanoparticles and their pDNA complexes in HeLa cells; and (3) incorporation of nuclear targeting agent into the nanoparticle/pDNA complexes to enhance the nuclear targeting ability. The PEI-based nanoparticles were able to transfect both human and non-human cell lines and their transfection efficiencies were cell-dependent. Within our four tested cell lines (MCF-7, BEL 7404, C6 and CHO-K1), gene transfer using PEI-based core-shell nanoparticles displayed gene expression levels comparable to, or even better than, the commercial Lipofectamine™ 2000. Confocal laser scanning microscopy showed that the nanoparticles and their pDNA complexes were effectively internalized into the HeLa cells. The in vitro time series experiments illustrated that both the nanoparticle/pDNA complexes and PEI-based nanoparticles were distributed in the cytoplasmic region after transfection for 10 and 60 min, respectively. Nuclear localization was also observed in both samples after transfection for 20 and 60 min, respectively. Incorporation of the high mobility group box 1 (HMGB1) protein for nuclear targeting has also been demonstrated with a simple approach: electrostatic complexation between the PEI-based nanoparticles and HMGB1. In the in vitro transfection study in MCF-7 cells, the expression level of the firefly luciferase gene encoded by the pDNA increased remarkably by up to eightfold when the HMGB1 protein was incorporated into the nanoparticle/pDNA complexes. Our results demonstrate that the PEI-based core-shell nanoparticles are promising nanocarriers for gene delivery.

Value of serum procalcitonin, neopterin, and C-reactive protein in differentiating bacterial from viral etiologies in patients presenting with lower respiratory tract infections

The values of procalcitonin (PCT), neopterin, and C-reactive protein (CRP) alone and in combination to differentiate bacterial from viral etiology in patients with lower respiratory tract infections (LRTIs) were evaluated. Sera obtained on the day of hospitalization for LRTI from 139 patients with confirmed bacterial etiology and 128 patients with viral etiology were examined. A further 146 sera from healthy Chinese subjects with no infection were included as controls. The area under the receiver operating characteristic (ROC) curve (area under curve [AUC]) for distinguishing bacterial from viral infections was 0.838 for CRP and 0.770 for PCT (P < 0.05). The AUC for distinguishing viral from bacterial infections was 0.832 for neopterin (P < 0.05). When the markers were used in combination, AUC of ROC (CRP/neopterin) was 0.857, whereas (CRP x PCT)/neopterin was 0.856. Combination of 2 or all 3 of the biomarkers may improve the discriminatory power in delineating bacterial versus viral etiology in LRTI.

Drug non-adherence and associated risk factors among Chinese geriatric patients in Hong Kong

OBJECTIVES

To study the prevalence of drug non-adherence among Chinese elderly people and its associated risk factors.

DESIGN

Cross-sectional survey.

SETTING

Medical and Geriatrics specialist out-patient clinic in a regional hospital.

PATIENTS

Elderly patients (> or =65 years) with chronic diseases requiring regular medications were selected by systematic sampling.

MAIN OUTCOME MEASURES

Drug non-adherence; potential risk factors studied include patients' factors, availability of assistance, and prescription factors.

RESULTS

Two hundred and nine elders participated with 84% response rate. Estimated mean prevalence rate of drug non-adherence was 37% (standard deviation, 7%). The risk factors for drug non-adherence were: (1) self-perceived adverse drug effects (odds ratio=2.5; 95% confidence interval, 1.2-5.2; P=0.017); (2) use of respiratory drugs (2.7; 1.0-7.5; P=0.048); (3) complicated drug regimens (7.4; 3.2-16.9; P<0.001); and (4) necessity to cut tablets (4.8; 2.1-10.7; P<0.001). Presence of caregiver/community nursing services assistance to pack medication (odds ratio=0.2; 95% confidence interval, 0.1-0.5; P=0.001), and the use of medication boxes (0.5; 0.3-1.0; P=0.050) were found to be the protective factors against drug non-adherence.

CONCLUSION

Drug non-adherence is an important concern in patient management. Medication regimen should be simplified as far as possible, in particular to avoid cutting pills or use of different dosage at different timing. Patients receiving drugs for respiratory diseases should be the first target group for intervention. Patients should be encouraged to voice out their perceived adverse drug effects.

Clopidogrel-induced hepatotoxicity after percutaneous coronary stenting

Clopidogrel, an adenosine diphosphate receptor blocker, is widely used as an adjunctive antiplatelet therapy in acute coronary syndrome and percutaneous coronary stenting. The occurrence of hepatotoxicity is rare. We describe the occurrence of symptomatic liver disease in a 74-year-old man 5 weeks following commencement of therapy with clopidogrel. The reported cases of clopidogrel-induced hepatotoxicity are reviewed and the clinical significance of this event are discussed.

Fixation using acetabular reconstruction cage and cancellous allografts for intraoperative acetabular fractures associated with cementless acetabular component insertion

Displaced acetabular fractures that occur during insertion of cementless acetabular component are a rare but very serious complication. We report two cases that were treated successfully with the utilization of an acetabular reconstruction cage and morsellized allografts.

Risk modeling, assessment, and management of lahar flow threat

The 1991 eruption of Mount Pinatubo in the Philippines is considered one of the most violent and destructive volcanic activities in the 20th century. Lahar is the Indonesian term for volcanic ash, and lahar flows resulting from the massive amount of volcanic materials deposited on the mountain's slope posed continued post-eruption threats to the surrounding areas, destroying lives, homes, agricultural products, and infrastructures. Risks of lahar flows were identified immediately after the eruption, with scientific data provided by the Philippine Institute of Volcanology, the U.S. Geological Survey, and other research institutions. However, competing political, economic, and social agendas subordinated the importance of scientific information to policy making. Using systemic risk analysis and management, this article addresses the issues of multiple objectives and the effective integration of scientific techniques into the decision-making process. It provides a modeling framework for identifying, prioritizing, and evaluating policies for managing risk. The major considerations are: (1) applying a holistic approach to risk analysis through hierarchical holographic modeling, (2) applying statistical methods to gain insight into the problem of uncertainty in risk assessment, (3) using multiobjective trade-off analysis to address the issue of multiple decisionmakers and stakeholders in the decision-making process, (4) using the conditional expected value of extreme events to complement and supplement the expected value in quantifying risk, and (5) assessing the impacts of multistage decisions. Numerical examples based on ex post data are formulated to illustrate applications to various problems. The resulting framework from this study can serve as a general baseline model for assessing and managing risks of natural disasters, which the Philippines' lead agency-the National Disaster Coordinating Council (NDCC)-and other related organizations can use for their decision-making processes.

Differential gene expression of hepatocellular carcinoma using cDNA microarray analysis

A cDNA microarray technique, which allows simultaneous analysis of differential expression of mRNA of over 4000 known human genes, was utilized to study the gene expression in 10 pairs of HCC and nontumorous tissues from ethnic Chinese patients in Hong Kong. A total of 211 genes were found to be highly expressed and 147 genes were downregulated in more than 1 out of 10 of the HCC pairs. The results were significant by two-tailed Wilcoxon test (P < or = 0.05 with 95% confidence) on the intensity of each DNA spot of the 10 HCC pairs. Six genes were highly expressed and 10 genes were downregulated in more than 30% of HCC pairs. Results are consistent with other published reports using traditional differential display, subtractive hybridization, or immunohistochemical staining methods. We also detected that beta-actin and glyceraldehyde 3-phosphate dehydrogenase (G3PDH), which have been commonly used as an internal standard control in mRNA expression studies, were highly expressed in HCC when compared with nontumorous tissue. It is concluded that cDNA microarray analysis is an effective method in the detection of differential gene expression in HCC.

IL-6 enhanced the retinoic acid-induced differentiation of human acute promyelocytic leukemia cells

It has been shown that retinoic acid (RA) induced the expression of interleukin-6 (IL-6) in human acute promyelocytic leukemia HL-60 cells. In the present study, we examined the ability of RA to induce the expression of gp130, the signal-transducing receptor component for IL-6, in HL-60 and a RA-supersensitive cell line HL-60/S4. We found that RA induced the expression of gp130, at both the mRNA and protein levels, in HL-60 and HL-60/S4 cells. Interestingly, the induction of gp 130 expression observed in the RA-supersensitive HL-60/S4 cells was much more pronounced than that observed in HL-60 cells. Furthermore, activation of the RA-induced gp130 by exogenous IL-6 potentiated the differentiating effects of RA. The synergistic effects observed for IL-6 and RA was also much stronger in HL-60/S4 cells than in HL-60 cells. Our findings suggest that the differentiating effects of RA may partially be mediated by the up-regulation of IL-6/gp130 signaling in HL-60 and HL-60/S4 cells.

Induction of TrkA expression by differentiation inducers in human myeloid leukemia KG-1 cells

We have recently reported that retinoic acid (RA) induced the expression of trkA, the high affinity receptor for nerve growth factor (NGF), in human myeloid leukemia KG-1 cells. In the present study, we report that the expression of trkA was also induced by several other differentiation inducers, including 1alpha, 25-dihydroxyvitamin D3 (Vit D3), 1-beta-D-arabinofuranosyl cytosine (Ara-C), sodium butyrate (NaBut), and phorbol 12-myristate 13-acetate (PMA). Interestingly, RA in combination with NaBut or PMA synergistically induced cellular differentiation as well as the expression of trkA in KG-1 cells. Furthermore, activation of the induced trkA receptor by exogenous NGF potentiated the differentiating effects of RA and NaBut. Our results demonstrated that the induction of trkA is an event associated with the differentiation of KG-1 cells. Our findings suggest that NGF, in addition to its pivotal roles in the nervous system, may also play important roles in hematopoietic differentiation.

Induction of gp130 and LIF by differentiation inducers in human myeloid leukemia K562 cells

It has been previously shown that phorbol 12-myristate 13-acetate (PMA), a potent differentiation inducer, induced the expression of both interleukin-6 (IL-6) and IL-6 receptor alpha component (IL-6Ralpha) in K562 leukemia cells. In the present study, we examined the ability of several differentiation inducers to regulate the expression of the signal-transducing receptor component for IL-6, gp130, and cytokine leukemia inhibitory factor (LIF) in K562 cells. We found that the expression of gp130 was dramatically induced at both the mRNA and protein levels by the two megakaryocytic inducers sodium butyrate (NaBut) and PMA. In contrast, the mRNA expression of LIF was induced by the two erythroid inducers 1-beta-D-arabinofuranosyl cytosine (Ara-C) and hemin. Furthermore, activation of the PMA-induced gp130 receptor by exogenous IL-6 potentiated the differentiating effects of PMA. Our findings suggest that IL-6/gp130 signaling may be involved in the regulation of the megakaryocytic differentiation of K562 cells.

The differentiating effect of retinoic acid and vincristine on acute myeloid leukemia

We have shown previously that granulocytic maturation and differentiation occurred when HL-60 cells and leukemia cells from a patient with acute promyelocytic leukemia (APL) were exposed to all-trans retinoic acid (ATRA) after treatment with a noncytotoxic concentration of vincristine (VCR), suggesting that VCR might have synergistic action with ATRA in the treatment of APL. Leukemic cells obtained from 24 patients with AML were exposed to 20 nM VCR for 1 h, followed by 1 microM ATRA for 6 days. Changes in the expression of myeloid leukocyte antigens were observed using flow cytometry. Differentiation phenotype as determined by the decrease or increase in maturation cell marker was observed in three samples treated with VCR alone, four samples treated with RA alone, and two samples treated with the combination of VCR and RA. The results suggest that treatment using VCR and ATRA may be effective in the differentiation therapy of AML.

Genetic and environmental risk factors for Parkinson's disease in a Chinese population

An epidemiological study of the environmental and genetic factors as well as the possible interplay between them was conducted among 215 patients with Parkinson's disease and 313 controls in a Chinese population in Hong Kong. In univariate analysis, a regular tea drinking habit was found to be a protective factor, which had not been reported before. Smoking (a protective factor), family history, duration of pesticide exposure (in years) in farming and pesticide exposure during farming in women (both risk factors) have been reported previously. In multivariate analysis, current smoking reached borderline significance at the 5% level and the variables, years exposed to pesticides and family history were significant at the 10% level. By contrast with the common occurrence of polymorphism of the CYP2D6 gene (a gene involved with xenobiotic metabolism) in white people, it is very rare in China and is not thought to be a significant factor contributing to Parkinson's disease in Chinese people.

Induction of NG108-15 cells differentiation by human bone marrow stromal cells

The survival and differentiation of neuronal cells is dependent on factors such as neurotrophins, cytokines and components of extracellular matrix. Bone marrow stromal cells have been shown to support the growth and differentiation of neuroblastoma cells. In an attempt to study the effects of bone marrow stromal cells on neuronal differentiation, we have co-cultured neuroblastoma x glioma hybrid NG108-15 cells with human bone marrow stromal cells. After co-culturing, clones exhibiting morphological differentiated phenotype and high level of neurofilament expression were isolated. Interestingly, these clones maintain their ability to proliferate in contrast to differentiated NG108-15 cells induced by dibutyryladenosine 3',5'-cyclic monophosphate. These results suggested that bone marrow stromal cells can induce partial differentiation of NG108-15 cells.

Intrinsic secondary structure of human TNFR-I mRNA influences the determination of gene expression by RT-PCR

The secondary structure of human tumor necrosis factor receptor I (TNFR-I) mRNA based on its lowest folding energy was predicted. Three combinations of primers selected from open-regions and four combinations of primers from closed-regions of TNFR-I mRNA structure were employed for single-tube reverse transcription-polymerase chain reaction (RT-PCR) for the determination of TNFR-I gene expression in U937 cell. All the primers were designed with the same criteria. However, the different primers generated distinct quantities of RT-PCR products from the same concentration of TNFR-I mRNA, implying that the determination of gene expression by RT-PCR was affected by the mRNA secondary structure. In addition, the sensitivity of the open-region RT-PCR was approximately one hundred-fold higher than that in the closed-regions of TNFR-I mRNA. The low efficiency of the closed-region RT-PCR was not correlated with the G/C content of the TNFR-I mRNA structure. These results suggest that consideration of the influence of intrinsic mRNA structure of a gene is essential prior to the determination of gene expression by quantitative RT-PCR, and this open-region strategy of primer design may yield an efficient primer for in vitro amplification of cDNA by RT-PCR.

Induction of TrkA receptor by retinoic acid in leukaemia cell lines

To explore the potential involvement of neurotrophins in the actions of retinoic acid (RA) on leukaemia differentiation, we examined the ability of RA to regulate the expression of neurotrophins and Trk receptors in several leukaemia cell lines. Expression of TrkA was dramatically induced by RA at both the mRNA and protein level in leukaemia cell lines K562 and KG-1. Furthermore, while no expression of trkB and trkC was detected, constitutive expression of nerve growth factor (NGF), neurotrophin-3 and neurotrophin-4/5 could be detected in leukemia cells. Our findings suggested that NGF/trkA may potentially be involved in the RA-induced differentiation of leukemia cells.

In vitro amplification of human basic fibroblast growth factor mRNA by RNA-specific exon-junction primers

Highly sensitive and RNA-specific primers for the determination of human basic fibroblast growth factor (bFGF) gene expression by RT-PCR were identified. The RNA-specific primers could amplify bFGF mRNA from 10 pg to 1 ng of total cellular RNA without interfering with the presence of genomic DNA of the cell. The feasible temperatures of the primers annealed to the template were 55 degrees C, 60 degrees C and 65 degrees C. In addition, different locations of primers on the bFGF mRNA molecule yielded distinct amounts of RT-PCR products from the same concentration of RNA, suggesting that the mRNA secondary structure of bFGF affected the RT-PCR. Owing to high sensitivity and specificity of the primers to bFGF RNA, the RNA-specific primers may be potentially utilized for the determination of human bFGF gene expression by in situ RT-PCR.

Identification and characterization of an RNA specific primer for human tumor necrosis factor receptor I (TNFR-I)

An RNA specific primer amplified TNFR-I cDNA from cellular RNA by single-tube (ST) RT-PCR without interfering with the presence of genomic DNA of cell was identified. The primer detected TNFR-I from 1 ng of cellular RNA by ST RT-PCR, and was not cross-reacted with TNFR-II despite of the homologous sequence between TNFR-I and -II. In addition, the mechanism of the RNA specificity of the primer was investigated. An intron of 0.43 kb was inserted in the 5'-925 of TNFR-I mRNA sequence. The result corresponded with the previous determination of TNFR-I gene structure. Thus, it appears that the RNA specificity of the primer might be resulted from the antisense primer hybridizing to exon-intron junction. Owing to its high sensitivity and specificity to TNFR-I RNA, the RNA specific primer may be potentially utilized for the determination of human TNFR-I gene expression by in situ RT-PCR.

Microtubule-dependent multilobular organization of the nucleus in sensitive and multidrug-resistant L0 leukemia cells

The relationship between the nuclear morphology and the microtubular organization of L100 and L1000 cells, two vincristine-induced multidrug resistant human acute lymphocytic leukemia cell lines, was examined and compared to that of L0 parental cells. The L0 parental cells contained a round nucleus and the microtubules were evenly distributed throughout the cytoplasm. In contrast, the microtubules of the L100 and L1000 cells were localized between the lobular structures of a multilobulated nucleus. Disassembly of microtubules in L100 and L1000 cells by colchicine resulted in the loss of the multilobulated morphology of the nucleus. While the total cellular content of tubulin of L0 and L100 cells was similar, the content of microtubules of L100 cells was only 55% of that observed in L0 cells. Two, 28 kDa (pI 6.9) and 31 kDa (pI 4.4), microtubule-associated proteins were found to be overexpressed in L100 and L1000 cells. The results indicate that the multilobulated nuclear morphology of L100 and L1000 cells is dependent upon the unique and intact organization of the microtubules; the distinct organization of the microtubules and the multilobular nuclear morphology of the two resistant cell lines may be due to the differential expression of specific microtubule-associated proteins.

Induction of trk receptors by retinoic acid in a human embryonal carcinoma cell line

Retinoic acid induced the differentiation of human embryonal carcinoma cells (NT2/D1) into several morphologically distinct cell types, including those resembling terminally differentiated postmitotic CNS neurones. The mechanism by which retinoic acid influences the process of neuronal differentiation in the CNS, however, remains unknown. In the present study, we have examined the ability of retinoic acid to induce the expression of the receptors that mediate the actions of the neurotrophins, using reverse transcription-polymerase chain reaction and Northern blot analysis. Our study demonstrated that the expression of mRNAs for three human trk receptors was significantly induced after treatment with retinoic acid. These findings suggest that the actions of retinoic acid on neuronal differentiation in the human CNS may potentially be mediated by the neurotrophins.

Pathogenesis of IgA nephropathy in ethanol consumption: animal model and cell culture studies

Using the intragastric ethanol infusion model of IgA nephropathy, we investigated the hypothesis that in this model mesangial changes commence prior to the deposition of IgA. We studied the two cellular components of the glomerular mesangium: the mononuclear phagocyte and the contractile mesangial cell. In the in vivo model, we observed a mononuclear phagocyte influx in the mesangium of alcoholic rats before the deposition of IgA. Using molecular techniques on cultured contractile mesangial cells, we demonstrated a threefold increase in interleukin-6 mRNA expression in contractile cells incubated with ethanol. These mesangial changes in the cellular composition, and in the autocrine cytokine system, suggest a direct role for ethanol in the pathogenesis of IgA nephropathy.

The effects of microtubule disrupting drugs on the differentiation of HL-60 leukemia cells

We and others have previously shown that microtubules (MT) are stained more intensely and are organized differently in differentiating leukemia cells. To study the effects of the MT disrupting drugs, colchicine (Coln) and vincristine (VCR), on the maturation process, HL-60 leukemia cells were pretreated with Coln or VCR for 1 h and then exposed to either retinoic acid (RA) or dimethyl sulfoxide (DMSO). Neither Coln nor VCR induced the differentiation of HL-60 cells, but in combination with RA increased the percentage of nitroblue tetrazolium-positive cells, the expression of the mature myelocyte surface marker Mo 1, and the content of MT over the effects produced by RA alone. In contrast, pretreatment with Coln or VCR delayed the commitment to a differentiation pathway induced by DMSO. The supra-additivity exhibited between Coln and RA required the administration of Coln prior to RA; thus, Coln had no effect when given two days after the cellular exposure to RA. The findings suggest that (a) a combination of non-cytotoxic concentrations of Coln or VCR with RA may have clinical utility as inducers of leukemia cell maturation, and (b) MT may be involved in modulating signal transduction during the initiation of HL-60 cell differentiation.

Changes in actin and actin-binding proteins during the differentiation of HL-60 leukemia cells

Actin and actin-binding proteins form a peripheral network on the cytosolic side of the plasma membrane. These cytoskeleton proteins are involved in functions that require cellular movement and may also have a role in modulating signal transduction during cellular proliferation and differentiation. To measure changes in F-actin and actin-binding proteins during HL-60 differentiation, cells were induced to mature along the granulocytic pathway by exposure to 1 microM retinoic acid (RA) for 5 days and were analyzed for F-actin and actin-binding proteins by flow cytometry. The amounts of F-actin and spectrin in untreated HL-60 cells and in those undergoing differentiation by treatment with the retinoid did not differ. N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)-phallacidin was used to measure F-actin content and a monoclonal antibody followed by fluorescence isothiocyanate-conjugated goat anti-mouse immunoglobulin antibody was used to measure the content of spectrin; cells were analyzed by flow cytometry. In contrast, cells exposed to RA contained larger amounts of alpha-actinin, vinculin, talin, lipocortin I, and lipocortin II, as determined with their respective antibodies followed by flow cytometric analysis as described above. An RA-supersensitive clone of HL-60, designated HL-60/S4, exhibited lower constitutive levels of alpha-actinin, vinculin, and talin but a higher constitutive level of lipocortin II than parental cells. Treatment of HL-60/S4 with RA led to increases in vinculin, talin, lipocortin I, and lipocortin II. An RA-resistant clone, designated HL-60/R3, constitutively expressed larger amounts of alpha-actinin, vinculin, lipocortin I, and lipocortin II than parental HL-60 cells. Treatment of HL-60/R3 with RA resulted in decreases in the amounts of these actin-binding proteins. Changes in actin-binding proteins that occur during the differentiation of HL-60 cells suggest that these proteins may be of importance to the expression of the mature phenotype.

Changes in microtubules, microtubule-associated proteins, and intermediate filaments during the differentiation of HL-60 leukemia cells

The cytoskeleton is composed mainly of microtubules (MT), microfilaments, and intermediate filaments (IF) that form a structural network which connects cellular membranes, cytoplasmic organelles, and the nucleus. Since the cytoskeleton may be involved in modulating signal transduction and in the morphological and structural changes that occur during cellular proliferation and differentiation, cytoskeletal changes were measured by immunofluorescence microscopy and fluorescence-activated cell sorter analysis during the differentiation of HL-60 leukemia cells induced by retinoic acid (RA). Differentiated HL-60 cells exhibited increased staining intensity and altered organization of MT and IF, as visualized by immunofluorescence microscopy with anti-tubulin monoclonal antibody and anti-vimentin antibody, respectively. A new procedure was developed and used to measure the content of the cytoskeletal components of HL-60 cells during the process of maturation. HL-60 cells were fixed with formaldehyde in an MT-stabilizing buffer, permeabilized using L-lysophosphatidylcholine, stained for immunofluorescent measurement with antibodies specific for particular cytoskeletal components, and analyzed by flow cytometry. Terminally differentiated cells produced by exposure to RA contained larger amounts of MT and the IF vimentin. During the course of the maturation process, a transient increase in the amounts of the microtubule-associated proteins, (MAPs) MAP2 and tau, occurred. An RA-supersensitive clone, designated HL-60/S4, and an RA-resistant clone, designated HL-60/R3, were developed by mutagenization and selection. Use of these clones supported the concept that the observed changes in MT, MAPs, and vimentin were associated with the differentiation process rather than being due to other effects produced by the retinoid. Thus, the findings suggest that changes in MT, MAPs, and IF are important to the terminal maturation of leukemia cells.

Gene construction and mutagenesis for site specific modification of protein with carbohydrate

We reported the construction of the structural gene for trans-activator (Tat) protein of human immunodeficiency virus. While maintaining the same amino acid sequence as the viral protein, the corresponding nucleotide sequence was modified to create additional recognition sites for restriction endonucleases and to prevent basepair mismatch during gene assembly. The oligonucleotides were synthesized chemically, purified and assembled into five gene blocks. The gene blocks were cloned into plasmid vectors and later reassembled into a complete gene. The use of gene blocks facilitated in vitro mutagenesis by the cassette mutagenesis method.

Relationship between 1-chloro-2,4-dinitrobenzene-induced cytoskeletal perturbations and cellular glutathione

Exposure of 3T3 cells to micromolar doses of 1-chloro-2,4-dinitrobenzene, a substrate for glutathione-S-transferase, resulted in a rapid depletion of total cellular glutathione accompanied by disassembly of microtubules as visualized by fluorescence microscopy. However, prolonged incubation resulted in cellular recovery from 1-chloro-2,4-dinitrobenzene insult as evidenced by a steady rise in total cellular glutathione accompanied by microtubule reassembly to their normal organization 5 hours after treatment. To evaluate the role of total cellular glutathione in modulating the 1-chloro-2,4-dinitrobenzene-induced cytoskeletal perturbation, we used 1-chloro-2,4-dinitrobenzene and/or buthionine sulfoximine, an effective irreversible inhibitor of glutathione synthesis, to manipulate cellular glutathione levels. Incubation of 3T3 cells with 2.5 microM 1-chloro-2,4-dinitrobenzene and 250 microM buthionine sulfoximine for 5 hours resulted in a complete depletion of total cellular glutathione accompanied by essentially complete loss of microtubules and marked alterations in the density and distribution pattern of microfilaments. Buthionine sulfoximine enhanced markedly the extent and duration of cellular glutathione depletion and the severity of microtubule disruption of 3T3 cells over the level achieved by 1-chloro-2,4-dinitrobenzene treatment alone. Furthermore, buthionine sulfoximine also prevented the restoration of cellular glutathione content and microtubule reassembly that normally were evident 5 hours after 1-chloro-2,4-dinitrobenzene treatment. Exposure of 3T3 cells to 50 microM 2-cyclohexene-1-one, which depletes free glutathione by conjugation, resulted in a complete depletion of total cellular glutathione content without altering the microtubule organization. These results suggest that the total glutathione content may be important for cellular recovery from 1-chloro-2,4-dinitrobenzene-mediated cytoskeletal injuries, and that microtubule disassembly observed in 1-chloro-2,4-dinitrobenzene-treated cells probably results from depletion of cellular glutathione coupled with binding to tubulin and/or other microtubule components.

Biological properties of suppressive E-receptor factor on lymphokine function

A potent immunosuppressive factor isolated from malignant ascites fluids showed serological cross-reactivity with the E-receptor of human peripheral blood T lymphocytes. Thus, this factor was named suppressive E-receptor (SER) factor. In this study, we examined the effect of this immunosuppressor, SER, on lymphokine functions of human mononuclear cells participating in polyclonal T cell activation. SER is active at nanomolar concentrations in vitro and the inhibitory effect of SER was most pronounced when added at the initiation of stimulation with phytohemagglutinin or anti-T3 antibody. Concomitant with the inhibition on PHA-induced DNA synthesis, lymphocytes that were treated with SER failed to progress beyond G1 phase of cell cycle. These growth-arrested cells did expire after 7 days of culture in vitro. This anti-proliferative effect of SER was more easily demonstrated with normal lymphoid cells in culture than transformed cells or fibroblast cells. SER effectively interfered with the lympho-proliferative properties of interleukin 2 (IL 2) on human peripheral blood mononuclear cells and an IL 2-dependent murine cytotoxic T cell line. However, excess quantities of exogenous IL 2, especially when added in conjunction with IL 1, were able to partially overcome the ability of SER to inhibit T cell proliferation. In contrast to the inhibition on DNA synthesis of human lymphoblasts, expression of IL 2 receptor was only minimally inhibited by SER during the first 24 h of culture (24% inhibition at 12 h and 34% inhibition at 24 h) but it was followed by full expression of IL 2 receptor by 48 h. Thus, SER merely reduced the rate of expression of IL 2 receptor and was not able to inhibit the transcription of new message from activated T lymphocytes. Taken together, these studies indicate that SER acts as a noncytolytic anti-proliferative factor on immune responses that are mediated by T cells. SER appears to act on a relatively late event during T cell activation, perhaps on some portion of the DNA replication pathway.

Distinctive RNA transcriptase, polyadenylic acid polymerase, and polyuridylic acid polymerase activities associated with Pichinde virus

Three RNA polymerase activities were found and associated with purified Pichinde virus, a member of the Arenaviridae. A heat-labile polymerase activity which required all four ribonucleoside triphosphates for optimal activity co-sedimented on sucrose gradient centrifugation with the viral ribonucleoprotein complex from detergent-disrupted virus preparations. This enzyme synthesized heteropolymers which represented about 23% of the genome RNA as determined by nucleic acid hybridization. Two relatively heat-stable polymerase activities which differed in their cation requirement and substrate specificity were recovered with the virus-associated ribosomes. These polymerase activities synthesized homopolymers of limited chain length: in the presence of 10 mM Mg2%, polyuridylic acid was made, whereas in the presence of 1 mM Mn2%, polyadenylic acid was made. The addition of complementary RNA synthesized with the viral transcriptase in vitro to the reaction mixture containing the polyadenylic acid polymerase activity resulted in the terminal addition of polyadenylic acid to the complementary RNA. The possible function of the ribosome-associated polymerase activities in the replication of the virus is discussed.