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Biomedical subjects

B Kim

Publications and source records attributed to B Kim.

At least 19 recordsLinked to original sources

Operative techniques and morbidity with subthalamic nucleus deep brain stimulation in 100 consecutive patients with advanced Parkinson's disease.

OBJECTIVE: Subthalamic nucleus (STN) stimulation for patients with medically refractory Parkinson disease (PD) is expanding. Reported experience has provided some indication of techniques, efficacy, and morbidity, but few centres have reported more than 50 patients. To expand this knowledge, we reviewed our experience with a large series of consecutive patients. METHODS: From March 1999 to September 2003, 191 subthalamic stimulator devices (19 unilateral) were implanted in 100 patients with PD at New York Presbyterian Hospital/Columbia University Medical Center. Sixteen patients had undergone a prior surgery for PD (pallidotomy, thalamotomy, or fetal transplant). Microelectrode guided implantations were performed using techniques similar to those described previously. Electrode implantation occurred 1-2 weeks before outpatient pulse generator implantation. RESULTS: Reductions of dyskinesias and off severity/duration were similar to prior published reports. Morbidity included: 7 device infections (3.7%), 1 cerebral infarct, 1 intracerebral haematoma, 1 subdural haematoma, 1 air embolism, 2 wound haematomas requiring drainage (1.0%), 2 skin erosions over implanted hardware (1.0%), 3 periprocedural seizures (1.6%), 6 brain electrode revisions (3.1%), postoperative confusion in 13 patients (6.8%), and 16 battery failures (8.4%). Of the 100 patients, there were no surgical deaths or permanent new neurological deficits. The average hospital stay for all 100 patients was 3.1 days. CONCLUSION: Subthalamic stimulator implantation in a large consecutive series of patients with PD produced significant clinical improvement without mortality or major neurological morbidity. Morbidity primarily involved device infections and hardware/wound revisions.

Adult↗

Cofilin activity during insulin-like growth factor I-stimulated neuroblastoma cell motility.

Insulin-like growth factor I (IGF-I) is a potent stimulator of neuroblastoma cell motility. Cell motility requires lamellipodium extension at the leading edge of the cell through organized actin polymerization, and IGF-I stimulates lamellipodial elaboration in human neuroblastoma cells. Rac is a Rho GTPase that stimulates lamellipodial formation via the regulation of actin polymerization. In this study, we show that IGF-I-stimulated phosphatidylinositol 3-kinase (PI-3K) activity promotes rac activation and subsequent activation of the down- stream effectors LIM kinase and cofilin. Overexpression of wild-type LIM kinase and wild-type Xenopus ADF/cofilin (XAC) suppresses IGF-I-stimulated motility in SH-SY5Y cells, while expression of dominant negative LIM kinase and constitutively active XAC increases SH-SY5Y motility in the absence of IGF-I stimulation. These results suggest that regulation by cofilin of actin depolymerization is important in the process of neuroblastoma cell motility, and IGF-I regulates cofilin activity in part through PI-3K, rac, and LIM kinase.

Actin Depolymerizing Factors↗

Dissolved organic matter from agricultural fields in the irrigation period.

The aim of this study was to quantify and characterize the dissolved organic carbon (DOC) of paddy fields and crop fields in Tottori, Japan. Dissolved organic carbon (DOC) and ultraviolet (UV) absorbance was measured for the filtrated water of each samples. DOC concentration and SUVA (specific UV absorbance) of biodegradation analysis samples were determined around 50 days after the incubation. In the Fukui paddy fields, DOC concentration varied seasonally from 1.1 to 10.1 mg.Cl(-1), showing higher concentration in heavy runoff of non-agriculture period in April. However, DOC concentration variation did not always correspond to rainfall. The Obadake paddy fields also showed a similar pattern with Fukui paddy fields. The daily DOC discharge per area in Fukui (up), Fukui (down), Obadake (south), Obadake (north) paddy fields influent from paddy fields were 0.02, 0.0161, 0.0135 and 0.0027 kg.a(-1).day(-1), respectively. These differences resulted from differences in agricultural types and customs of farmers according to paddy fields and fields. Also, SUVA (an indirect means to evaluate humic substances (hydrophobic fraction)) of the studied influent waters from paddy fields were generally lower than the influent waters from crop fields. The non-biodegradable DOC accounted for 50.2-98%, 46.8-85.5% of the total DOC in the paddy fields and crop fields.

Agriculture↗

Randomized trial of tacrolimus versus cyclosporine in steroid withdrawal in living donor renal transplant recipients.

The introduction of new immunosuppressants has prompted trials of steroid withdrawal. However, several groups have reported a higher incidence of rejection. We conducted a randomized two-arm, parallel-group, open-label, prospective study to compare steroid withdrawal (at 6 months posttransplant) from the regimens of tacrolimus + mycophenolate mofetil (MMF) (FK group) versus cyclosporine + MMF (CSA group). The entry criteria were recipients of first living donor transplants with no diabetes mellitus (DM), congestive heart failure, chronic liver disease, or acute rejection within 6 months posttransplant. The primary endpoint was a biopsy-proven acute rejection episode or treatment failure within 1 year posttransplant. While 87 recipients were assigned to FK (n = 43) and CSA groups (n = 44) before transplantation, 76 recipients (FK 39, CSA 37) could be tapered off steroids at 6 months posttransplant, since 11 were excluded due to acute rejection within 6 months posttransplant (FK two, CSA three) or protocol violations (FK two, CSA four). After steroid withdrawal, the incidence of acute rejection episodes was 0% in the FK group and 13.5% in the CSA group (P < .05). Other results at 12 months posttransplantation were comparable: the incidences of DM 7.8% versus 0% (FK group vs CSA group), hypercholesterolemia 41.0% versus 59.5%, hypertensives 48.7% versus 59.6% as well as the levels of plasma creatinine 1.21 +/- 0.24 versus 1.31 +/- 0.50 mg/dL (P > .05 in every variable). These data suggest that steroid withdrawal is successful in first living donor renal transplant recipients. Tacrolimus may be significantly more effective than cyclosporine to prevent acute rejection after steroid withdrawal.

Adrenal Cortex Hormones↗

Nitric oxide-mediated vasorelaxation by Rhizoma Ligustici wallichii in isolated rat thoracic aorta.

The vasorelaxant effect of Rhizoma Ligustici wallichii and its possible mechanism of action on the vasomotor tone of the rat thoracic aortic rings were examined in an organ bath. Chloroform extracts of Rhizoma Ligustici wallichii (Ch1LW) elicited a dose-dependent, transient, relaxing response in endothelium-intact rat aorta contracted with norepinephrine (NE). This relaxant effect was abolished by removal of the endothelium and also by pretreatment with nitric oxide synthase inhibitors. Neither a muscarinic receptor antagonist nor a cyclooxygenase inhibitor altered the Ch1LW-induced relaxation. Tetramethylpyrazine, derived from Rhizoma Ligustici wallichii as a potent vasodilating component, induced a complete relaxation in both endothelium-intact and denuded rat aortas contracted by NE, but nitric oxide synthase inhibitors did not affect the relaxation. Ch1LW-induced endothelium-dependent relaxation was mediated by nitric oxide released from the endothelium, and could be caused by component(s) other than tetramethylpyrazine.

Animals↗

Usefulness of reversed display of soft-copy abdominal radiographs for urinary calculi detection.

PURPOSE: To determine the usefulness of reversed display of soft-copy abdominal radiographs for urinary calculi detection. MATERIAL AND METHODS: Sixty radiographs with a single urinary calculus less than 5 mm in the long diameter (15 in the kidney; 15 in the proximal ureter; 15 in the mid-ureter, 15 in the distal ureter) and 15 radiographs without calculi were evaluated. Four readers blinded to the presence or absence of urinary calculi on each radiograph reviewed the radiographs in the conventional display, reversed display, and combination of conventional and reversed displays at 1-week intervals. All images were evaluated in random order and the presence or absence of urinary calculi was interpreted using the confidence score from 1 to 5. RESULTS: Multireader analysis for calculi in all locations showed a greater area under the receiver operating curve for combination of the two displays (0.764) than for the conventional display alone (0.655) (P=0.031). In the single-reader analysis for calculi in all locations, the third reader showed a greater area under the receiver operating curve for the reversed display (0.784) than for the conventional display (0.622) (P=0.027). Multireader analysis of the calculi in the kidney showed a greater area under the receiver operating curve for combination of the two displays (0.824) than for the conventional display alone (0.703) (P=0.043). CONCLUSION: The reversed display of soft-copy abdominal radiographs may be useful for urinary calculi detection.

Area Under Curve↗

Suppressive effects of PG201, an ethanol extract from herbs, on collagen-induced arthritis in mice.

OBJECTIVE: PG201 has been formulated using 12 herbs known to have anti-inflammatory and protective effects on damaged tissue and bone among other functions. The present study was done in order to assess the therapeutic effects of PG201 in collagen-induced arthritis (CIA) in mice. METHODS: DBA/1 mice were immunized with bovine type II collagen. After a second collagen immunization, mice were treated with PG201 orally at 10 mg/kg once a day for 18 days. Paws were evaluated macroscopically for redness, swelling and deformities. The levels of TNF-alpha and IL-1beta in the ankle were examined. The severity of arthritis within the knee joints was evaluated by histological assessment of cartilage destruction and pannus formation. Molecular indicators related to CIA pathology were analysed by measuring the serum levels of matrix metalloproteinase 2 (MMP-2), tissue inhibitor of matrix metalloproteinase 2 (TIMP-2) and the anti-inflammatory cytokines interleukin (IL)-4 and IL-10. RESULTS: Administration of PG201 significantly suppressed the progression of CIA and inhibited the production of TNF-alpha and IL-1beta in the paws. The erosion of cartilage was dramatically reduced in mouse knees after treatment with PG201. In the serum of PG201-treated mice, the level of TIMP-2 and the ratio of TIMP-2 to MMP-2 were significantly elevated, and the level of IL-4, but not of IL-10, was increased. CONCLUSION: Administration of PG201 has therapeutic effects on CIA. Protection of cartilage was particularly prominent. PG201 is a potential therapy for rheumatoid arthritis.

Animals↗

Commissioning, evaluation, quality assurance and clinical application of a virtual micro MLC technique.

Multileaf collimators (MLCs) are a valuable tool in modern radiation therapy, offering flexible and convenient field shaping. One disadvantage, however, is the undulation of the dose distribution at the edge shaped by the leaves due to the finite leaf width. An attempt to reduce the effect of this undulation is the objective of the commercial linear accelerator package HD270, which incorporates three-dimensional couch translation together with leaf adjustment to emulate finer leaf widths. In this paper we report on the commissioning and evaluation of this feature, together with the development of a process for quality assurance, as well as description of a clinical application of this technique. It is concluded that this technique could be applied reliably to situations currently utilizing MLC for shielding, with little added cost in treatment time, provided that a comprehensive quality assurance program is in place to monitor the performance of this complicated procedure.

Algorithms↗

Mucosal immune responses following oral immunization with rotavirus antigens encapsulated in alginate microspheres.

Availability of effective oral vaccine delivery vehicles should contribute to the success of oral immunization in domestic animals. To achieve this goal, we evaluated alginate microspheres for their capacity to induce mucosal immune responses following oral and enteric immunizations. Mice were immunized with either live porcine rotavirus (PRV) or its recombinant VP6 protein, encapsulated in alginate microspheres or unencapsulated. VP6-specific IgG (but no IgA) antibodies were detected in the sera of mice after a single intraperitoneal (i.p.) immunization with either VP6 in Incomplete Freund's adjuvant (VP6-IFA), VP6 in alginate microspheres (VP6-MS) or with live PRV in incomplete Freund's adjuvant (PRV-IFA). In contrast, VP6-specific IgA (but no IgG) was detected in culture supernatants of mesenteric lymph nodes from mice immunized i.p. with either VP6-IFA or with PRV-IFA. Oral immunization with VP6-MS induced the highest level of VP6-specific fecal IgA antibody, similar to responses induced by oral immunization with live PRV. Furthermore, the VP6-specific fecal IgA could be boosted by a secondary i.p. immunization with VP6. Further experiments were performed in a sheep intestinal 'loop' model to evaluate uptake of microspheres by Peyer's patches. Microspheres containing colloidal carbon were specifically bound and transported by follicle-associated epithelium of Peyer's patches. Additionally, mucosal immune responses were detected following enteric immunization with porcine serum albumin (PSA) encapsulated in alginate microspheres. Our results confirm that alginate microspheres are an effective oral delivery vehicle for protein antigens and intestinal IgA antibody responses are induced by antigens encapsulated in alginate microspheres without any additional mucosal adjuvant. These investigations confirm that alginate microspheres have the potential as an effective delivery vehicle for oral immunization of ruminants.

Administration, Oral↗

Experimental infection of piglets with transmissible gastroenteritis virus: a comparison of three strains (Korean, Purdue and Miller).

Eighty-four colostrum-deprived piglets aged 1 day were inoculated with either a Korean strain of transmissible gastroenteritis virus (TGEV) or one of two American strains (Purdue and Miller). The purpose was to compare, by morphometric analysis and in-situ hybridization, the Korean strain with the two American strains in respect of pathogenicity and viral distribution over a period of 72 h. The progression of infection in pigs infected with the Korean strain was much slower than that in pigs infected with either of the two American strains. At 6 h post-inoculation (hpi), the mean score of the villous height/crypt depth (VH/CD) ratio of pigs inoculated with the Purdue or Miller strain was significantly less than that of pigs inoculated with the Korean strain or uninfected control pigs. At 12-72 hpi, however, the VH/CD ratio of all infected pigs was significantly less than that of control pigs. In-situ hybridization showed significant differences between the Korean and American strains in terms of the amount of TGEV nucleic acid at 6, 12 and 60 hpi. TGEV nucleic acid was detected in the duodenum, jejunum and ileum of pigs inoculated with the Purdue or Miller strain but only in the jejunum and ileum of those inoculated with the Korean strain. The results suggested that the Korean strain was less virulent than the two American strains.

Animals↗

Structural relaxation, self-diffusion, and kinetic heterogeneity in the two-dimensional lattice Coulomb gas.

We present Monte Carlo simulation results on the equilibrium relaxation dynamics in the two-dimensional lattice Coulomb gas, where finite fractions f of the lattice sites are occupied by positive charges. In the case of high-order rational values of f close to the irrational number 1-g [g identical with (square root of 5-1)/2 is the golden mean], we find that the system exhibits, for a wide range of temperatures above the first-order transition, a glassy behavior resembling the primary relaxation of supercooled liquids. Single-particle diffusion and structural relaxation show that there exists a breakdown of proportionality between the time scale of diffusion and that of structural relaxation analogous to the violation of the Stokes-Einstein relation in supercooled liquids. Suitably defined dynamic cooperativity is calculated to exhibit the characteristic nature of dynamic heterogeneity present in the system.

Journal Article↗

Insulin-like growth factor I stimulates motility in human neuroblastoma cells.

Motility is an important process that contributes to cancer cell spread. Growth factors are key regulators of motility in many cell types. Insulin-like growth factor I (IGF-I) causes SH-SY5Y human neuroblastoma cells to undergo dynamic morphological changes, leading to the extension of lamellipodia. IGF-I stimulated lamellipodia extension requires signaling through both phosphatidylinositol 3-kinase (PI3-K) and MAP kinase pathways. IGF-I, over a period of hours, stimulates SH-SY5Y and SHEP neuroblastoma cells to become more motile. While SH-SY5Y and SHEP cells use different insulin receptor substrate (IRS) isoforms to transduce signals from the IGF-I receptor, IGF-I has the same relative effect on the motility of both cell lines. Blocking the PI3-K and MAP kinase pathways attenuates the ability of IGF-I to increase motility. Overexpression of PTEN also attenuates IGF-I mediated motility. These results delineate some of the proximal events in the signaling mechanism utilized by IGF-I to stimulate cell motility.

Cell Division↗

Characterization of full-length HIV type 1 subtype C sequences from South Africa.

Four full-length genome subtype C sequences from South Africa, three of which are being used for vaccine development, were characterized. Three isolates were obtained from recently infected individuals in KwaZulu/Natal: Du151, Du422, and Du179. A fourth isolate, CTSc2, was obtained from an individual residing in Cape Town. All four strains used the CCR5 coreceptor, although Du179 also used CXCR4. The four isolates clustered within subtype C, but the three Du isolates formed a subcluster with a bootstrap value of 100%, with CTSc2 outside the subcluster. None of the strains showed evidence of intersubtype recombination, as expected from the predominance of subtype C in South Africa. All 4 isolates had a 16-amino acid truncation on the 3' end of the Rev protein, identified in other subtype C isolates. Like many other subtype C strains, Du151, Du422, and Du179 had three NF-kappa B-binding sites in the LTR; however, CTSc2 had only two.

Genome, Viral↗

Crystal structure of LexA: a conformational switch for regulation of self-cleavage.

LexA repressor undergoes a self-cleavage reaction. In vivo, this reaction requires an activated form of RecA, but it occurs spontaneously in vitro at high pH. Accordingly, LexA must both allow self-cleavage and yet prevent this reaction in the absence of a stimulus. We have solved the crystal structures of several mutant forms of LexA. Strikingly, two distinct conformations are observed, one compatible with cleavage, and the other in which the cleavage site is approximately 20 A from the catalytic center. Our analysis provides insight into the structural and energetic features that modulate the interconversion between these two forms and hence the rate of the self-cleavage reaction. We suggest RecA activates the self-cleavage of LexA and related proteins through selective stabilization of the cleavable conformation.

Amino Acid Sequence↗

High proportion of unrelated HIV-1 intersubtype recombinants in the Mbeya region of southwest Tanzania.

BACKGROUND: In Mbeya, a rural region of southwest Tanzania, HIV-1 subtypes A, C and D have been co-circulating since the early 1990s. OBJECTIVE: To define to what extent the co-existence of subtypes has led to recombinant HIV-1 strains and whether there is evidence for epidemic spread of any circulating recombinant form. METHODS: Nine HIV-1-seropositive young adults from Mbeya Town with no evident high-risk behaviour contributed peripheral blood mononuclear cells for this study. Nine virtually full-length-genome-sequences were amplified from this DNA and phylogenetically analysed. RESULTS: Out of the nine samples, two were subtype A (22%), two were subtype C (22%) and five were recombinants (56%): four A/C recombinants and one C/D recombinant. None of the recombinants were related to each other; all of them had different mosaic structures. Most of the genome in the recombinants was subtype C. CONCLUSION: A high proportion of unrelated intersubtype recombinants, none of them apparently spreading in the population, may be present in southwest Tanzania.

Adolescent↗

The AG recombinant IbNG and novel strains of group M HIV-1 are common in Cameroon.

The genetic diversity of group M HIV-1 is highest in west central Africa. Blood samples from four locations in Cameroon were collected to determine the molecular epidemiology of HIV-1. The C2-V5 region of envelope was sequenced from 39 of the 40 samples collected, and 7 samples were sequenced across the genome. All strains belonged to group M of HIV-1. The circulating recombinant form CRF02 AG (IbNG) was the most common strain (22/39, 56%). Two of these were confirmed by full genome analysis. Four samples (4/39, 10%) clustered with the sub-subtype F2 and one of these was confirmed by full genome sequencing. Recombinant forms, each different but containing subtype A, accounted for the next most common form (7/39, 18%). Among these recombinants, those combining subtypes A and G were the most common (4/7, 57%). Also found were 3 subtype A, 2 subtype G, and 1 subtype B strain. Many recombination break points were shared between IbNG and the other AG recombinants, though none of these other AG recombinants included IbNG as a parent. This suggests that there was an ancestral AG recombinant that gave rise to CRF02 AG (IbNG), the successful circulating recombinant form, and to others that were less successful and are now rare.

Acquired Immunodeficiency Syndrome↗