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Biomedical subjects

Henry Lin

Publications and source records attributed to Henry Lin.

At least 19 recordsLinked to original sources
PubMed2006

Most early disseminated cancer cells detected in bone marrow of breast cancer patients have a putative breast cancer stem cell phenotype.

PURPOSE: The presence of disseminated tumor cells (DTC) in the bone marrow of breast cancer patients is an acknowledged independent prognostic factor. The biological metastatic potential of these cells has not yet been shown. The presence of putative breast cancer stem cells is shown both in primary tumors and distant metastases. These cells with a CD44(+)CD24(-/low) phenotype represent a minor population in primary breast cancer and are associated with self-renewal and tumorigenic potential. Recognizing the potential effect of prevalence of putative stem cells among DTC, we evaluated the bone marrow DTC. EXPERIMENTAL DESIGN: We employed the double/triple-staining immunohistochemistry protocol and modified the established bone marrow cytokeratin (CK) staining protocol by adding steps for additional antigens, CD44 and/or CD24. We evaluated 50 bone marrow specimens, previously categorized as CK(+) from early breast cancer patients. CK(+) cells were examined for CD44 and CD24 expression by light microscopy, fluorescence microscopy, and spectral imaging. RESULTS: We detected the putative stem cell-like phenotype in all CK(+) specimens. The mean prevalence of putative stem/progenitor cells was 72% and median prevalence was 65% (range, 33-100%) among the overall DTC per patient, compared with primary tumors where this phenotype is reported in <10% of cells. CONCLUSIONS: This is the first evidence of the existence of the putative stem-like phenotype within the DTC in bone marrow in early breast cancer patients. All patients had a putative stem cell phenotype among the DTC and most individual DTC showed such phenotype. Future molecular characterization of these cells is warranted.

Bone Marrow↗
PubMed2006

Comparative gene expression analysis of NKT cell subpopulations.

Natural killer T (NKT) cells are a lymphocyte lineage, which has diverse immune regulatory activities in many disease settings. Most previous studies have investigated the functions of this family of cells as a single entity, but more recent evidence highlights the distinct functional and phenotypic properties of NKT cell subpopulations. It is likely that the diverse functions of NKT cells are regulated and coordinated by these different NKT subsets. Little is known about how NKT subsets differ in their interactions with the host. We have undertaken the first microarray analysis comparing the gene expression profiles of activated human NKT cell subpopulations, including CD8(+) NKT cells, which have often been overlooked. We describe the significant gene expression differences among NKT cell subpopulations and some of the molecules likely to confer their distinct functional roles. Several genes not associated previously with NKT cells were shown to be expressed differentially in specific NKT cell subpopulations. Our findings provide new insights into the NKT cell family, which may direct further research toward better manipulation of NKT cells for therapeutic applications.

CD4-Positive T-Lymphocytes↗
PubMed2006

Diffusion-weighted MR imaging abnormalities in pediatric patients with surgically-treated intracranial mass lesions.

INTRODUCTION: Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) technique that measures the degree of water diffusion in vivo. DWI abnormalities are frequently observed on immediate postoperative imaging following surgical resection of gliomas in adults. These abnormalities subsequently demonstrate contrast enhancement, which may be confused with lesion recurrence. The purpose of this study was to investigate the occurrence of these postoperative abnormalities in pediatric patients with intracranial mass lesions. METHODS: Thirty-three consecutive patients <or=18 years old with a newly diagnosed intracranial mass lesion underwent MRI, including DWI, before and immediately after surgical treatment. RESULTS: The median patient age was 9.9 years (range 0.2-18 years). Supratentorial and infratentorial lesions were identified in 22 and 11 patients, respectively. Infiltrative and noninfiltrative, as well as benign and malignant lesions, were included. Postoperative imaging demonstrated areas of reduced diffusion adjacent to the resection cavity in 20 (61%) cases. The median volume of these areas was 1.7 cm3 (range 0.3 cm3-12.0 cm3). Subsequent imaging studies in 9 of the 18 cases showed contrast enhancement in the area corresponding to the DWI abnormality. There were no clinical deficits attributable to any of the diffusion abnormalities. There was no association between the occurrence of these abnormalities and whether the lesion was infiltrative, non-infiltrative, benign, or malignant. CONCLUSIONS: DWI abnormality on immediate postoperative MRI is common following surgery for newly diagnosed intracranial mass lesions in pediatric patients. Focal contrast enhancement in the postoperative period may be confused with recurrence for some lesions. Our study suggests that immediate postoperative DWI is useful in interpreting new areas of focal contrast enhancement on subsequent imaging in children who have had surgery for brain tumors.

Adolescent↗
PubMed2006

Acetyl-CoA synthetase overexpression in Escherichia coli demonstrates more efficient acetate assimilation and lower acetate accumulation: a potential tool in metabolic engineering.

The overexpression of acetyl-CoA (CoA) synthetase (ACS) in Escherichia coli showed significant reduction in acetate during glucose fermentation. It also greatly enhanced acetate assimilation when acetate was used as a carbon source. These features are ideal for applications in metabolic engineering. ACS overexpression can be strategically applied to reduce acetate byproduct, recover wasted carbon, and redirect carbon flux toward more favorable pathways. The native acs gene was cloned and overexpressed in E. coli. Studies showed significant effects on acetate production and assimilation in cultures grown in minimal and complex media with glucose or acetate as the carbon source.

Acetate-CoA Ligase↗
PubMed2006

Analysis of the effect of different NKT cell subpopulations on the activation of CD4 and CD8 T cells, NK cells, and B cells.

OBJECTIVE: NKT cells have diverse immune regulatory functions including activation of cells involved in Th1- and Th2-type immune activities. Most previous studies have investigated the functions of NKT cells as a single family but more recent evidence indicates the distinct functional properties of NKT cell subpopulation. This study aims to determine whether NKT cell subpopulations have different stimulatory activities on other immune cells that may affect the outcome of NKT cell-based immunotherapy. METHODS: NKT cells and NKT cell subpopulations (CD4(+)CD8(-), CD4(-)CD8(+), CD4(-)CD8(-)) were cocultured with PBMC and their activities on immune cells including CD4(+) and CD8(+) T cells, NK cells, and B cells were assessed by flow cytometry. The production of cytokines in culture was measured by enzyme-linked immunsorbent assay. RESULTS: The CD4(+)CD8(-) NKT cells demonstrated substantially greater stimulatory activities on CD4(+) T cells, NK cells, and B cells than other NKT cell subsets. The CD4(-)CD8(+) NKT cells showed the greatest activity on CD8(+) T cells, and were the only NKT cell subset that activated these immune cells. The CD4(-)CD8(-) NKT cells showed moderate stimulatory activity on CD4(+) T cells and the least activity on other immune cells. CONCLUSION: The results here suggest that NKT cell subpopulations differ in their abilities to stimulate other immune cells. This highlights the potential importance of manipulating specific NKT cell subpopulations for particular therapeutic situations and of evaluating subpopulations, rather than NKT cells as a group, during investigation of a possible role of NKT cells in various disease settings.

Coculture Techniques↗
PubMed2006

Kallikrein-mediated proteolysis regulates the antimicrobial effects of cathelicidins in skin.

The presence of cathelicidin antimicrobial peptides provides an important mechanism for prevention of infection against a wide variety of microbial pathogens. The activity of cathelicidin is controlled by enzymatic processing of the proform (hCAP18 in humans) to a mature peptide (LL-37 in human neutrophils). In this study, elements important to the processing of cathelicidin in the skin were examined. Unique cathelicidin peptides distinct from LL-37 were identified in normal skin. Through the use of selective inhibitors, SELDI-TOF-MS, Western blot, and siRNA, the serine proteases stratum corneum tryptic enzyme (SCTE, kallikrein 5) and stratum corneum chymotryptic protease (SCCE, kallikrein 7) were shown to control activation of the human cathelicidin precursor protein hCAP18 and also influence further processing to smaller peptides with alternate biological activity. The importance of this serine protease activity to antimicrobial activity in vivo was illustrated in SPINK5-deficient mice that lack the serine protease inhibitor LEKTI. Epidermal extracts of these animals show a significant increase in antimicrobial activity compared with controls, and immunoabsorption of cathelicidin diminished antimicrobial activity. These observations demonstrate that the balance of proteolytic activity at an epithelial interface will control innate immune defense.

Animals↗
PubMed2006

Immunogene therapy as a treatment for malignant brain tumors in young mice.

OBJECT: New and innovative forms of effective treatments for malignant brain tumors in children are urgently needed. The authors have previously shown that intracerebral injection into the tumor bed of allogeneic fibroblasts genetically engineered to secrete interleukin-2 (IL-2) results in prolongation of survival and an antitumor immunocytotoxic response in adult mice that harbor intracerebral gliomas. The first goal of this study was to determine if malignant gliomas (GI261) could be treated in mice (C57BL/6) in the pediatric age group (weanlings [2-3 weeks old] and adolescents [3-4 weeks old]). The second goal was to determine the effectiveness of using IL-2-secreting allogeneic fibroblasts as a protective vaccine to prevent the development of intracerebral gliomas in these young mice. METHODS: Using GI261 glioma cells derived from a spontaneously arising glioma in C57BL/6 immunocompetent mice, animals 2 to 4 weeks of age received an intracranial injection of 5 x 10(4) tumor cells into the right frontal lobe through a bur hole. The treatment vaccine consisted of 10(6) allogeneic IL-2-secreting fibroblasts, given at the time of tumor injection (treatment experiments) or at three weekly intervals prior to tumor injection (protection experiments). Control groups received either medium or nonsecreting allogeneic fibroblasts. The effects of this treatment on survival and long-term immunity were investigated. The results demonstrate a significant prolongation of survival in animals harboring intracerebral gliomas that were treated with intracerebral injections of IL-2-secreting allogeneic fibroblasts (p < 0.05). Morbidity and mortality rates did not increase as a result of intracerebral immunization. Compared with naive controls, long-term survivors demonstrated immune memory, as evidenced by prolongation of survival when they were rechallenged with tumor cells. The results of the protection experiment demonstrate a significant delay (p < 0.005) in the development of gliomas in the animals pretreated with either allogeneic nonsecreting or allogeneic IL-2-secreting fibroblasts prior to the introduction of tumor cells. In addition, in 78% of these animals a tumor did not develop when rechallenged. CONCLUSIONS: These results demonstrate the efficacy and safety of using intratumoral injection of IL-2-secreting allogeneic fibroblasts as a treatment or protective vaccine in young mice. It is hoped that these preclinical studies will lead to a clinical trial for the treatment of malignant brain tumors in children.

Age Factors↗
PubMed2006

Molecular biology of bladder cancer: prognostic and clinical implications.

The role of various molecular determinants involved in the genesis, progression, and outcome of bladder cancer has been the focus of investigations for the past 2 decades. Increasingly, the analysis of the interplay between these molecular factors is taking center stage. We review herein the studies examining the effects of deregulation of the various molecules implicated in the cell cycle, apoptosis, and angiogenesis pathways and analyze the central role of p53 in regulating these pathways. Technological advancements enable detection and quantification of gene transcripts and protein products, helping us move toward achieving the goal of establishing diagnostic, prognostic, and therapeutic marker panels. Recent studies have therefore focused on multiple-marker analyses to generate informative panels that can have greater clinical value for bladder cancer management. The use of molecular marker panels can provide a more objective alternative to clinical parameters for diagnosis and treatment decisions. Clinical trials aimed at treating urothelial carcinoma based on a patient's molecular profile can be predicted to empower clinicians to personalize patient management through increased therapeutic efficacy.

Apoptosis Regulatory Proteins↗
PubMed2006

Advantages of a unique DNA-based vaccine in comparison to paclitaxel in treatment of an established intracerebral breast cancer in mice.

In this study we compared the benefits of treating C3H/He mice with an established intracerebral breast carcinoma by immunization with a unique DNA-based vaccine to chemotherapy with paclitaxel. Prior studies revealed the immunotherapeutic properties of a vaccine prepared by transfer of genomic DNA from breast cancer cells into a highly immunogenic cell line. Here, C3H/He mice with an established intracerebral breast cancer were treated either by injection into the tumor bed through a unique cannula system with the cell based vaccine or with paclitaxel administered intraperitoneally. Both treatment strategies were effective in prolonging survival and stimulating a systemic anti-tumor immune response (p< 0.025). However, unlike mice treated with the vaccine, the animals that received paclitaxel alone displayed significant toxic side effects. No additional therapeutic advantage was detected when these two treatment strategies were combined. The vaccine tended to provide a somewhat better therapeutic and clearly better systemic immunologic effect based on two independent spleen cell assays in comparison to paclitaxel.

Journal Article↗
PubMed2005

Ultrasonography in community emergency departments in the United States: access to ultrasonography performed by consultants and status of emergency physician-performed ultrasonography.

STUDY OBJECTIVE: Nearly all emergency medicine residency programs provide some training in emergency physician-performed ultrasonography, but the extent of emergency physician-performed ultrasonography in community emergency departments (EDs) is not known. We seek to determine the state of ultrasonography in community EDs in terms of access to ultrasonography by other specialists and performance of ultrasonography by emergency physicians. METHODS: A 6-page survey that addressed access to ultrasonography performed by other specialists and emergency physician-performed ultrasonography was designed and pilot tested. A list of all US ED directors was obtained from the American College of Emergency Physicians. Twelve hundred of 5264 EDs were randomly selected to receive the anonymous survey, with responses tracked by separate postcard. There were 3 mailings from Fall 2003 to Spring 2004. RESULTS: Overall response rate was 61% (684/1130). Respondents who self-reported as being academic with emergency medicine residents were excluded from further analysis (n=35). A sensitivity analysis (reported in parentheses) was performed on the key outcome question to adjust for response bias. As reported by ED directors, ultrasonography was available in the ED for use by emergency physicians at all times in 19% of EDs (12% to 28%), with an additional 15% (9% to 21%) reporting a machine available for use by emergency physicians in some capacity and 66% (51% to 80%) reporting that there was no access to a machine for emergency physician use. ED directors reported being requested or required to limit ultrasonography orders performed by radiology in 41% of EDs, with less timely access to radiology-performed ultrasonography in off hours. Of EDs with emergency physician-performed ultrasonography, the most common applications were Focused Assessment with Sonography for Trauma (FAST) examination (85%), code situation (72%), and check for pericardial effusion (67%). Of physicians performing ultrasonography, 16% stated they were currently requesting reimbursement (billing). The primary reason cited for not implementing emergency physician-performed ultrasonography was lack of emergency physician training. For the statement "emergency medicine residents now starting residency should be trained to perform and interpret focused bedside ultrasonography," 84% of ED directors agreed, 14% were neutral, and less than 2% disagreed. CONCLUSION: Community ED directors continue to report barriers to obtaining ultrasonography from consultants, especially in off hours. Nineteen percent of community ED directors report having a machine available for emergency physician use at all times; however, two thirds of EDs report no access to ultrasonography for emergency physician use. A majority of community ED directors support residency training in emergency physician-performed ultrasonography.

Clinical Competence↗
PubMed2005

Development of a metabolic network design and optimization framework incorporating implementation constraints: a succinate production case study.

We have developed a pathway design and optimization scheme that accommodates genetically and/or environmentally derived operational constraints. We express the full set of theoretically optimal pathways in terms of the underlying elementary flux modes and then examine the sensitivity of the optimal yield to a wide class of physiological perturbations. Though the scheme is general it is best appreciated in a concrete context: we here take succinate production as our model system. The scheme produces novel pathway designs and leads to the construction of optimal succinate production pathway networks. The model predictions compare very favorably with experimental observations.

Computer Simulation↗
PubMed2005

Complementary detection of prostate-specific antigen using In2O3 nanowires and carbon nanotubes.

We report complementary detection of prostate-specific antigen (PSA) using n-type In2O3 nanowires and p-type carbon nanotubes. Our innovation involves developing an approach to covalently attach antibodies to In2O3 NW surfaces via the onsite surface synthesis of phosphonic acid-succinylimide ester. Electronic measurements under dry conditions revealed complementary response for In2O3 NW and SWNT devices after the binding of PSA. Real-time detection in solution has also been demonstrated for PSA down to 5 ng/mL, a benchmark concentration significant for clinical diagnosis of prostate cancer, which is the most frequently diagnosed cancer.

Indium↗
PubMed2005

Chemostat culture characterization of Escherichia coli mutant strains metabolically engineered for aerobic succinate production: a study of the modified metabolic network based on metabolite profile, enzyme activity, and gene expression profile.

Various Escherichia coli mutant strains designed for succinate production under aerobic conditions were characterized in chemostat. The metabolite profiles, enzyme activities, and gene expression profiles were studied to better understand the metabolic network operating in these mutant strains. The most efficient succinate producing mutant strain HL27659k was able to achieve a succinate yield of 0.91 mol/mol glucose at a dilution rate of 0.1/h. This strain has the five following mutations: sdhAB, (ackA-pta), poxB, iclR, and ptsG. Four other strains involved in this study were HL2765k, HL276k, HL2761k, and HL51276k. Strain HL2765k has mutations in sdhAB, (ackA-pta), poxB and iclR, strain HL276k has mutations in sdhAB, (ackA-pta) and poxB, strain HL2761k has mutations in sdhAB, (ackA-pta), poxB and icd, and strain HL51276k has mutations in iclR, icd, sdhAB, (ackA-pta) and poxB. Enzyme activity data showed strain HL27659k has substantially higher citrate synthase and malate dehydrogenase activities than the other four strains. The data also showed that only iclR mutation strains exhibited isocitrate lyase and malate synthase activities. Gene expression profiles also complemented the studies of enzyme activity and metabolites from chemostat cultures. The results showed that the succinate synthesis pathways engineered in strain HL27659k were highly efficient, yielding succinate as the only major product produced under aerobic conditions. Strain HL27659k was the only strain without pyruvate accumulation, and its acetate production was the least among all the mutant strains examined.

Aerobiosis↗
PubMed2005

Fed-batch culture of a metabolically engineered Escherichia coli strain designed for high-level succinate production and yield under aerobic conditions.

An aerobic succinate production system developed by Lin et al. (Metab Eng, in press) is capable of achieving the maximum theoretical succinate yield of 1.0 mol/mol glucose for aerobic conditions. It also exhibits high succinate productivity. This succinate production system is a mutant E. coli strain with five pathways inactivated: DeltasdhAB, Delta(ackA-pta), DeltapoxB, DeltaiclR, and DeltaptsG. The mutant strain also overexpresses Sorghum vulgare pepc. This mutant strain is designated HL27659k(pKK313). Fed-batch reactor experiments were performed for the strain HL27659k(pKK313) under aerobic conditions to determine and demonstrate its capacity for high-level succinate production. Results showed that it could produce 58.3 g/l of succinate in 59 h under complete aerobic conditions. Throughout the entire fermentation the average succinate yield was 0.94+/-0.07 mol/mol glucose, the average productivity was 1.08+/-0.06 g/l-h, and the average specific productivity was 89.77+/-3.40 mg/g-h. Strain HL27659k (pKK313) is, thus, capable of large-scale succinate production under aerobic conditions. The results also showed that the aerobic succinate production system using the designed strain HL27659k(pKK313) is more practical than conventional anaerobic succinate production systems. It has remarkable potential for industrial-scale succinate production and process optimization.

Aerobiosis↗
PubMed2005

Effect of carbon sources differing in oxidation state and transport route on succinate production in metabolically engineered Escherichia coli.

In mixed-acid fermentation, succinate synthesis requires one mole of phosphoenolpyruvate (PEP), one mole of CO2, and two moles of NADH for every mole of succinate to be formed. Different carbon sources with different properties were used to address these requirements. Sorbitol generates one more mole of NADH than glucose. Fermentation of sorbitol was shown in this study (and by others) to produce significantly more succinate than fermentation of glucose, due to increased NADH availability. Xylose fermentation conserves the intracellular PEP pool, since its transport does not require the phosphotransferase system normally used for glucose transport. The extra PEP can then be assimilated in the succinate pathway to improve production. In this study, fermentation of xylose did yield higher succinate production than glucose fermentation. Subsequent inactivation of the acetate and lactate pathways was performed to study metabolite redistribution and the effect on succinate production. With the acetate pathway inactivated, significant carbon flux shifted toward lactate rather than succinate. When both acetate and lactate pathways were inactivated, succinate yield ultimately increased with a concomitant increase in ethanol yield.

Acetates↗
PubMed2005

Genetic reconstruction of the aerobic central metabolism in Escherichia coli for the absolute aerobic production of succinate.

Most reported efforts to enhance production of the industrially valuable specialty chemical succinate have been done under anaerobic conditions, where E. coli undergoes mixed-acid fermentation. These efforts have often been hampered by the limitations of NADH availability, poor cell growth, and slow production. An aerobic succinate production system was strategically designed that allows E. coli to produce and accumulate succinate efficiently and substantially as a product under absolute aerobic conditions. Mutations in the tricarboxylic acid cycle (sdhAB, icd, iclR) and acetate pathways (poxB, ackA-pta) of E. coli were created to construct the glyoxylate cycle for aerobic succinate production. Experiments in flask studies showed that 14.28 mM of succinate could be produced aerobically with a yield of 0.344 mole/mole using 55 mM glucose. In aerobic batch reactor studies, succinate production rate was faster, reaching 0.5 mole/mole in 24 h with a concentration of 22.12 mM; further cultivation showed that succinate production reached 43 mM with a yield of 0.7. There was also substantial pyruvate and TCA cycle C(6) intermediate accumulation in the mutant. The results suggest that more metabolic engineering improvements can be made to this system to make aerobic succinate production more efficient. Nevertheless, this aerobic succinate production system provides the first platform for enhancing succinate production aerobically in E. coli based on the creation of a new aerobic central metabolic network.

Aerobiosis↗
PubMed2005

Major vascular injury after laparoscopic tubal ligation.

Laparoscopy has become an established approach with diverse applications in both diagnostic and therapeutic surgical procedures. In general, the procedure is safe and effective and offers the advantage of being less invasive than conventional surgery. Complications after laparoscopy are uncommon but among them major vascular injury is potentially the most fatal, with recognition or mortality typically occurring intra-operatively or in the immediate post-operative period. We report the case of a delayed emergency department presentation of a major vascular injury after an elective laparoscopic tubal ligation. The prevalence, diagnosis, pathophysiolgy and management of major vascular injury after laparoscopic surgery is discussed.

Abdominal Pain↗