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Míguez-Burbano MJ, Angarita I, Shultz JM, Shor-Posner G, Klaskala W, Duque JL, Lai H, Londoño B, Baum MK. HIV-related high risk sexual behaviors and practices among women in Bogotá, Colombia. Women Health 2001; 30:109-19. [PMID: 10983613 DOI: 10.1300/j013v30n04_08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Determinants associated with high-risk sexual behaviors were investigated in 1,133 sexually active women in Bogotá, Colombia. A self-administered questionnaire was completed by two groups of women: 721 representing the general population (GP), and 412 commercial sex workers (CSWs). High-risk sexual behaviors for HIV/AIDS were evident in both groups. Nevertheless, consistent condom use was reported by only 6% of the GP group, as compared to 67% of the CSWs. Failure to recognize high-risk routes for HIV infection was indicated in 69% of the GP women for anal sex, and by the majority of both groups for intercourse during menses (56% GP women and 54% CSWs). Multivariate analysis revealed that education level, actual age, and age of first sex experience were significant predictors of high-risk sexual practices. The necessity for educational programs regarding high-risk sexual practices and risk of HIV/ AIDS is evident for HIV/AIDS prevention.
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Lu JZ, Zhang JG, Lai H. [The relationship between ECochG and glycerol test in vertigo patients (report of 112 cases)]. LIN CHUANG ER BI YAN HOU KE ZA ZHI = JOURNAL OF CLINICAL OTORHINOLARYNGOLOGY 2000; 14:510-1. [PMID: 12563946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
OBJECTIVE For further investigating the diagnostic value of the ECochG in Meniere's disease. METHOD 112 vertigo patients including Meniere's disease, sudden deafness, cervical vertigo and other vertigo disease, had been done ECochG, glycerol test, audiometry and caloric test. The results were compared with those of normal group. RESULT In Meniere's disease, the positive rate of abnormal-SP/AP in ECochG was 54.69% and the positive rate of glycerol test was 53.12%. There are no statistics difference (P > 0.05) between this two tests with X analysis. CONCLUSION We think that the glycerol test and other relative examination are necessary for the diagnosis of Meniere's disease while the-SP/AP > 0.4 ms in the examination of ECochG.
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Siniscalco M, Robledo R, Orru S, Contu L, Yadav P, Ren Q, Lai H, Roe B. A plea to search for deletion polymorphism through genome scans in populations. Trends Genet 2000; 16:435-7. [PMID: 11203137 DOI: 10.1016/s0168-9525(00)02101-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Qiu SR, Lai H, Yarmoff JA. Self-limiting growth of metal fluoride thin films by oxidation reactions employing molecular precursors. PHYSICAL REVIEW LETTERS 2000; 85:1492-1495. [PMID: 10970537 DOI: 10.1103/physrevlett.85.1492] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2000] [Indexed: 05/23/2023]
Abstract
FeF (2) films are grown by the reaction of XeF (2) and SeF (6) with iron foil. The growth initially follows the Mott-Cabrera parabolic rate law, indicating that the process is diffusion limited. At a certain film thickness, however, the growth abruptly stops, with the thickness using XeF (2) being nearly double that with SeF (6). It is suggested that the shutdown is due to the inability of the molecules to dissociate when too far from the substrate and that SeF (6) must approach more closely than XeF (2). This work suggests the use of molecular precursors to grow thin films via a self-limiting chemical process.
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Lai H, Tsumori T, Shiroyama T, Yokota S, Nakano K, Yasui Y. Morphological evidence for a vestibulo-thalamo-striatal pathway via the parafascicular nucleus in the rat. Brain Res 2000; 872:208-14. [PMID: 10924695 DOI: 10.1016/s0006-8993(00)02457-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We observed by anterograde and retrograde tracing techniques that projection fibers originating from the medial vestibular nucleus (MVe) of the rat terminated in the dorsal two-thirds of the lateral part of the parafascicular thalamic nucleus (PF), where neurons sending their axons to the dorsolateral part of the striatum existed. It was further revealed that the vestibular fibers made asymmetrical synaptic contacts mainly with dendrites and additionally with soma of the striatum-projecting PF neurons. These data suggest that output signals from the MVe may be transmitted disynaptically to the striatal neurons via the PF neurons.
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Lai S, Chen J, Celentano D, Page JB, Lai H, Yang J, Liu W, McCoy CB, Yu XF. Adoption of injection practices in heroin users in Guangxi Province, China. J Psychoactive Drugs 2000; 32:285-92. [PMID: 11061679 DOI: 10.1080/02791072.2000.10400451] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
This preliminary study collected data from 326 heroin users in Guangxi Province, China, in 1997. Logistic regression analysis was performed to identify the risk factors for injection. Survival analysis identified factors independently associated with time from initiation of heroin use to adoption of injection. Four factors were independently associated with injection: number of friends who used heroin in the last year, duration of heroin use, dose of heroin consumed, and total number of times detoxified in drug treatment and rehabilitation centers. Only gender and duration of heroin use were independently associated with time to first injection. Median time to first injection was 11 months for males and 22 months for females. Median time to first injection varied by age. Median time to injection for those who used heroin for more than one year was 8.1 months; it was 19.1 months for on to five years of use, and 40.5 months for more than five years of use. This study's preliminary findings suggest that younger, more recent heroin users, and males are at increased risk of becoming injectors, a major risk behavior for HIV acquisition.
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Lai S, Lai H, Krongrad A, Lamm S, Schwade J, Roos BA. Radical prostatectomy: geographic and demographic variation. Urology 2000; 56:108-15. [PMID: 10869637 DOI: 10.1016/s0090-4295(00)00557-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Previous reports have documented a geographic variation in the use of radical prostatectomy. We examined whether this phenomenon can be explained by factors other than geography alone. METHODS This study was based on the data from nine geographic regions of the Surveillance, Epidemiology, and End Results (SEER) program for the years 1983 through 1994. Patients with localized or regional prostate cancer were included in the analysis. Logistic regression analysis was used to investigate the influence of geographic and demographic factors on the use of radical prostatectomy. The squared multiple correlation coefficient R(2) was used to measure the proportion of variation in the selection of radical prostatectomy explained by each factor of interest. RESULTS As previously reported, the use of radical prostatectomy was significantly associated with geographic location; the degree of geographic variation varied as a function of age and was most dramatic in the youngest (younger than 45 years) and the oldest (75 years or older) groups. Overall, however, geography explained less than 2% of the total variation in the use of radical prostatectomy. Age was the most important factor that influenced the use of radical prostatectomy. CONCLUSIONS Geography explains only a small proportion of the variation in the use of radical prostatectomy. In fact, of the factors examined, only age appeared to meaningfully explain the variation in the use of radical prostatectomy. Overall, our ability to explain the variation in the use of radical prostatectomy remains meager, and new factors must be identified if we are to better understand how patients and physicians make clinical decisions.
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Lai H, Carino M. Intracerebroventricular injection of mu- and delta-opiate receptor antagonists block 60 Hz magnetic field-induced decreases in cholinergic activity in the frontal cortex and hippocampus of the rat. Bioelectromagnetics 2000; 19:432-7. [PMID: 9771587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
In previous research, we have found that acute exposure to a 60 Hz magnetic field decreased cholinergic activity in the frontal cortex and hippocampus of the rat as measured by sodium-dependent high-affinity choline uptake activity. We concluded that the effect was mediated by endogenous opioids inside the brain because it could be blocked by pretreatment of rats before magnetic field exposure with the opiate antagonist naltrexone, but not by the peripheral antagonist naloxone methiodide. In the present study, the involvement of opiate receptor subtypes was investigated. Rats were pretreated by intracerebroventricular injection of the mu-opiate receptor antagonist, beta-funaltrexamine, or the delta-opiate receptor antagonist, naltrindole, before exposure to a 60 Hz magnetic field (2 mT, 1 hour). It was found that the effects of magnetic field on high-affinity choline uptake in the frontal cortex and hippocampus were blocked by the drug treatments. These data indicate that both mu- and delta-opiate receptors in the brain are involved in the magnetic field-induced decreases in cholinergic activity in the frontal cortex and hippocampus of the rat.
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84
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Lai H, Singh NP. Acute exposure to a 60 Hz magnetic field increases DNA strand breaks in rat brain cells. Bioelectromagnetics 2000; 18:156-65. [PMID: 9084866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Acute (2 h) exposure of rats to a 60 Hz magnetic field (flux densities 0.1, 0.25, and 0.5 mT) caused a dose-dependent increase in DNA strand breaks in brain cells of the animals (assayed by a microgel electrophoresis method at 4 h postexposure). An increase in single-strand DNA breaks was observed after exposure to magnetic fields of 0.1, 0.25, and 0.5 mT, whereas an increase in double-strand DNA breaks was observed at 0.25 and 0.5 mT. Because DNA strand breaks may affect cellular functions, lead to carcinogenesis and cell death, and be related to onset of neurodegenerative diseases, our data may have important implications for the possible health effects of exposure to 60 Hz magnetic fields.
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85
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Lai H, Singh NP. Melatonin and a spin-trap compound block radiofrequency electromagnetic radiation-induced DNA strand breaks in rat brain cells. Bioelectromagnetics 2000; 18:446-54. [PMID: 9261542 DOI: 10.1002/(sici)1521-186x(1997)18:6<446::aid-bem7>3.0.co;2-2] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Effects of in vivo microwave exposure on DNA strand breaks, a form of DNA damage, were investigated in rat brain cells. In previous research, we have found that acute (2 hours) exposure to pulsed (2 microseconds pulses, 500 pps) 2450-MHz radiofrequency electromagnetic radiation (RFR) (power density 2 mW/cm2, average whole body specific absorption rate 1.2 W/kg) caused an increase in DNA single- and double-strand breaks in brain cells of the rat when assayed 4 hours post exposure using a microgel electrophoresis assay. In the present study, we found that treatment of rats immediately before and after RFR exposure with either melatonin (1 mg/kg/injection, SC) or the spin-trap compound N-tert-butyl-alpha-phenylnitrone (PBN) (100 mg/kg/injection, i.p.) blocks this effects of RFR. Since both melatonin and PBN are efficient free radical scavengers it is hypothesized that free radicals are involved in RFR-induced DNA damage in the brain cells of rats. Since cumulated DNA strand breaks in brain cells can lead to neurodegenerative diseases and cancer and an excess of free radicals in cells has been suggested to be the cause of various human diseases, data from this study could have important implications for the health effects of RFR exposure.
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Lai H, Carino MA, Ushijima I. Acute exposure to a 60 Hz magnetic field affects rats' water-maze performance. Bioelectromagnetics 2000; 19:117-22. [PMID: 9492169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Rats were trained in six sessions to locate a submerged platform in a circular water-maze. They were exposed to a 1 mT, 60 Hz magnetic field for one hour in a Helmholtz coil system immediately before each training session. In addition, one hour after the last training session, they were tested in a probe trial during which the platform was removed and the time spent in the quadrant of the maze in which the platform was located during the training sessions was scored. Control animals were sham-exposed using the exposure system operating with the coils activated in an anti-parallel direction to cancel the fields. A group of "non-exposed" control animals was also included in the study. There was no significant difference between the magnetic field-exposed and control animals in learning to locate the platform. However, swim speed of the magnetic field-exposed rats was significantly slower than that of the controls. During the probe trial, magnetic field-exposed animals spent significantly less time in the quadrant that contained the platform, and their swim patterns were different from those of the controls. These results indicate that magnetic field exposure causes a deficit in spatial "reference" memory in the rat. Rats subjected to magnetic field exposure probably used a different behavioral strategy in learning the maze.
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87
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Lai H, Carino M. 60 Hz magnetic fields and central cholinergic activity: effects of exposure intensity and duration. Bioelectromagnetics 2000; 20:284-9. [PMID: 10407513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
In previous research, we have found that acute exposure to a 60 Hz magnetic field caused a decrease in cholinergic activity in the frontal cortex and hippocampus of the rat. In the present study, the effects of exposure to different intensities of the magnetic field and durations of exposure were investigated. Rats were exposed to a 60 Hz magnetic field for 60 min at a flux density of either 0.5, 1.0, 1.5, or 2.0 mT. A significant decrease in cholinergic activity was observed in the frontal cortex and hippocampus immediately after exposure to the 2.0 mT field. No significant effect was observed at lower intensities. In another experiment, effect of exposure to a 1.0 mT magnetic field for 30, 45, 60, and 90 min was investigated. A decrease in cholinergic activity was found in both brain areas after 90 min of exposure. No significant effect was observed after shorter durations of exposure. In a further experiment, the exposure duration was extended to 3 h at flux densities of 0.5, 0.1, and 0.05 mT. A significant decrease in cholinergic activity was observed in the frontal cortex and hippocampus of the rat immediately after exposure to all the intensities. It is concluded that the intensity and duration of exposure interact. By increasing the duration of exposure, effects can be observed at lower intensities.
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Abstract
Medium-chain triacylglycerols (MCTs) have been shown to provide better nutritional support than long-chain triacylglycerols (LCTs). This study compares the efficacy of MCT combined with LCT with LCT alone in pediatric patients with surgical stress. Two groups of patients (n = 19 in each) received equivalent amounts of glucose (12 g. kg. d) and amino acids (2 g. kg. d), but one group received 10% Lipofundin MCT/LCT and the other received 10% LCT (1.5 g. kg. d) in a randomized study. Total parenteral nutrition (TPN) was given for 14 d. Blood and urine samples were collected before and after TPN administration for determination of various biochemical parameters. Indirect calorimetry was also performed to determine respiratory quotients and fuel utilization. After 14 d of TPN in the MCT/LCT group, there was a significantly higher blood lymphocyte percentage, a decreasing tendency of serum asparate aminotransferase and of total and direct bilirubin (P < 0.05). These changes were not observed in the LCT group. A significantly better nitrogen balance and a higher ketogenesis from day 3 were observed in the MCT/LCT group. The MCT/LCT group showed a more marked increased utilization of fat than the LCT group, whereas carbohydrate oxidation was less in the MCT/LCT group than in the LCT group (P < 0.05). In children after surgery, MCT/LCT is more protein sparing and induces a better immune response when compared with LCT-containing lipid emulsion. A TPN regimen containing MCT/LCT is likely to result in rapid oxidation of fats for energy without compromising the respiratory system.
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Campbell Dwyer EJ, Lai H, MacDonald RC, Salvato MS, Borden KL. The lymphocytic choriomeningitis virus RING protein Z associates with eukaryotic initiation factor 4E and selectively represses translation in a RING-dependent manner. J Virol 2000; 74:3293-300. [PMID: 10708446 PMCID: PMC111830 DOI: 10.1128/jvi.74.7.3293-3300.2000] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Only a few host cell proteins that associate with arenaviruses have been identified. To date, the arenavirus Z protein associates with the promyelocytic leukemia protein PML and the ribosomal P proteins. The majority of PML is present in nuclear bodies which are translocated to the cytoplasm by infection with the arenavirus, lymphocytic choriomeningitis virus (LCMV). The Z protein is a small zinc-binding RING protein with an unknown function which is required for the viral life cycle. Here, we demonstrate an association between Z and the host cell translation factor, eukaryotic initiation factor 4E (eIF-4E) in infected and transfected cells. Z's association with both ribosomal proteins and this translation factor led us to investigate whether Z could modulate host cell translation. In cell culture, Z selectively represses protein production in an eIF-4E-dependent manner. Specifically, we see reduction in cyclin D1 protein production with no effect on glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in cells transfected with Z. Previous reports indicate that cyclin D1 is sensitive to eIF-4E levels, whereas GAPDH is not. Consistent with this, we observe preferential downregulation of cyclin D1 during infection and no effect on GAPDH. Further, no changes in RNA levels were observed for cyclin D1 or GAPDH transcripts. The interaction between eIF-4E and Z may provide a mechanism for slower growth observed in infected cells and a viral strategy for establishing chronic infection.
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Tsumori T, Yokota S, Lai H, Yasui Y. Monosynaptic and disynaptic projections from the substantia nigra pars reticulata to the parafascicular thalamic nucleus in the rat. Brain Res 2000; 858:429-35. [PMID: 10708697 DOI: 10.1016/s0006-8993(99)02368-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We examined a direct pathway and an indirect pathway via the reticular thalamic nucleus (RT) from the substantia nigra pars reticulata (SNr) to the parafascicular thalamic nucleus (PF) by using anterograde and retrograde tract tracing methods. After biotinylated dextranamine (BDA) injection into the dorsolateral part of the SNr, many labeled fibers and axon terminals were distributed in the ventral part of the RT, as well as in the ventrolateral part of the PF, bilaterally with an ipsilateral dominance. After BDA injection into the ventral part of the RT, a plexus of labeled axons was found bilaterally with an ipsilateral dominance in the ventrolateral part of the PF. After combined injections of BDA into the dorsolateral part of the SNr and cholera toxin B subunit (CTb) into the ventrolateral part of the PF on the same side, overlapping distribution of BDA-labeled fibers and CTb-labeled neurons was observed in the ventral part of the RT ipsilateral to the injection sites, where the BDA-labeled axon terminals made symmetrical synaptic contacts with soma and dendrites of the CTb-labeled neurons.
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Leung TF, Chik KW, Li CK, Lai H, Shing MM, Chan PK, Lee V, Yuen PM. Incidence, risk factors and outcome of varicella-zoster virus infection in children after haematopoietic stem cell transplantation. Bone Marrow Transplant 2000; 25:167-72. [PMID: 10673675 DOI: 10.1038/sj.bmt.1702119] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We report a retrospective analysis of VZV infection after haematopoietic stem cell transplantation (HSCT) in children. Thirty-three (30%) of the total 109 children who were transplanted during a 7 year period developed post-transplant VZV infection. Twenty-four of these 33 (73%) children had VZV infection within 1 year following HSCT. The cumulative incidences of post-transplant VZV infection at 1 and 5 years were 26% and 45%, respectively. The positive and negative predictive values of pretransplant VZV serology in recipients on the development of HZ following HSCT were 39% and 88%, respectively. Pretransplant VZV seropositivity in recipients was the only risk factor for post-transplant herpes zoster (HZ) infection on multivariate analysis. All patients responded to acyclovir. The median duration of VZV infection was 5 days. Three (11%) and one (3%) children with HZ developed visceral dissemination and post-herpetic neuralgia, respectively. No mortality was directly attributed to VZV infection. VZV infection remains a major cause of morbidity in children after HSCT. Further studies are warranted to evaluate the potential use of VZV vaccine in these children. Bone Marrow Transplantation (2000) 25, 167-172.
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Fletcher M, Miguez-Burbano MJ, Shor-Posner G, Lopez V, Lai H, Baum MK. Diagnosis of human immunodeficiency virus infection using an immunoglobulin E-based assay. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2000; 7:55-7. [PMID: 10618277 PMCID: PMC95822 DOI: 10.1128/cdli.7.1.55-57.2000] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/1999] [Accepted: 09/29/1999] [Indexed: 11/20/2022]
Abstract
Immunoglobulin assays that are sensitive and specific for detecting human immunodeficiency virus type 1 (HIV-1) infection are especially important in developing countries where PCR and viral culture may not be readily available. Immunoglobulin E (IgE), which is elevated in HIV-1 infection, is the only antibody that does not cross the placenta, making it potentially valuable for viral detection in both children and adults. This study developed an assay for detection of HIV specific IgE antibodies in adults. A total of 170 serum samples from 170 adults (116 HIV positive and 54 HIV negative) were analyzed. Serum or plasma samples were treated by using the protein G affinity method. The HIV status was determined by using two IgG enzyme-linked immunosorbent assays (ELISAs) and one Western blot evaluation. The IgE enzyme immunoassay test for HIV-1 correctly identified the HIV status in 98.8% of the samples (168 of 170). One false-positive and one false-negative test occurred with the IgE ELISA, as well as with the IgG ELISA test but were correctly identified by the IgE test. Analysis of the data demonstrated a high specificity (99%) and sensitivity (99%) of the IgE test, with 95% confidence intervals. The IgE assay appears to be sensitive and specific, suggesting that IgE-specific antibodies offer an effective method to detect HIV-1 infection in adults.
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Wang B, Lai H. Acute exposure to pulsed 2450-MHz microwaves affects water-maze performance of rats. Bioelectromagnetics 2000; 21:52-6. [PMID: 10615092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Rats were trained in six sessions to locate a submerged platform in a circular water maze. They were exposed to pulsed 2450-MHz microwaves (pulse width 2 micros, 500 128;pulses/s, average power density 2 mW/cm(2), average whole body specific absorption rate 1.2 W/kg) for 1 h in a circular waveguide system immediately before each training session. One hour after the last training session, they were tested in a probe trial during which the platform was removed and the time spent in the quadrant of the maze in which the platform had been located during the 1-min trial was scored. Three groups of animals, microwave-exposed, sham-exposed, and cage control, were studied. Microwave-exposed rats were slower than sham-exposed and cage control rats in learning to locate the platform. However, there was no significant difference in swim speed among the three groups of animals, indicating that the difference in learning was not due to a change in motor functions or motivation. During the probe trial, microwave-exposed animals spent significantly less time in the quadrant that had contained the platform, and their swim patterns were different from those of the sham-exposed and cage control animals. The latter observation indicates that microwave-exposed rats used a different strategy in learning the location of the platform. These results show that acute exposure to pulsed microwaves caused a deficit in spatial "reference" memory in the rat.
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Yang P, Pimental R, Lai H, Marcus S. Direct activation of the fission yeast PAK Shk1 by the novel SH3 domain protein, Skb5. J Biol Chem 1999; 274:36052-7. [PMID: 10593886 DOI: 10.1074/jbc.274.51.36052] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The p21-activated kinase (PAK) homolog Shk1 is essential for cell viability in the fission yeast Schizosaccharomyces pombe. Roles have been established for Shk1 in the regulation of cell morphology, sexual differentiation, and mitosis in S. pombe. In this report, we describe the genetic and molecular characterization of a novel SH3 domain protein, Skb5, identified as a result of a two-hybrid screen for Shk1 interacting proteins. S. pombe cells carrying a deletion of the skb5 gene exhibit no discernible phenotypic defects under normal growth conditions, but when subjected to hypertonic stress, become spheroidal in shape and growth impaired. Both of these defects can be suppressed by overexpression of the Shk1 modulator, Skb1. The growth inhibition that results from overexpression of Shk1 in S. pombe cells is markedly suppressed by a null mutation in the skb5 gene, suggesting that Skb5 contributes positively to the function of Shk1 in vivo. Consistent with this notion, we show that Skb5 stimulates Shk1 catalytic function in S. pombe cells. Furthermore, and perhaps most significantly, we show that bacterially expressed recombinant Skb5 protein directly stimulates the catalytic activity of recombinant Shk1 kinase in vitro. These and additional data described herein demonstrate that Skb5 is a direct activator of Shk1 in fission yeast.
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Chang E, Bartholomeusz G, Pimental R, Chen J, Lai H, Wang LH, Yang P, Marcus S. Direct binding and In vivo regulation of the fission yeast p21-activated kinase shk1 by the SH3 domain protein scd2. Mol Cell Biol 1999; 19:8066-74. [PMID: 10567532 PMCID: PMC84891 DOI: 10.1128/mcb.19.12.8066] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Ste20/p21-activated kinase homolog Shk1 is essential for viability and required for normal morphology, mating, and cell cycle control in the fission yeast Schizosaccharomyces pombe. Shk1 is regulated by the p21 G protein Cdc42, which has been shown to form a complex with the SH3 domain protein Scd2 (also called Ral3). In this study, we investigated whether Scd2 plays a role in regulating Shk1 function. We found that recombinant Scd2 and Shk1 interact directly in vitro and that they interact in vivo, as determined by the two-hybrid assay and genetic analyses in fission yeast. The second of two N-terminal SH3 domains of Scd2 is both necessary and sufficient for interaction with Shk1. While full-length Scd2 interacted with only the R1 N-terminal regulatory subdomain of Shk1, a C-terminal deletion mutant of Scd2 interacted with both the R1 and R3 subdomains of Shk1, suggesting that the non-SH3 C-terminal domain of Scd2 may be involved in defining specificity in SH3 binding domain recognition. Overexpression of Scd2 stimulated the autophosphorylation activity of wild-type Shk1 in fission yeast but, consistent with results of genetic analyses, did not stimulate the activity of a Shk1 protein lacking the R1 subdomain. Results of additional two-hybrid experiments suggest that Scd2 may stimulate Shk1 catalytic function, at least in part, by positively modulating protein-protein interaction between Cdc42 and Shk1. We propose that Scd2 functions as an organizing center, or scaffold, for the Cdc42 complex in fission yeast and that it acts in concert with Cdc42 to positively regulate Shk1 function.
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Abstract
In this paper, we describe a method for the visualization of double-strand breaks in a single electrostretched Escherichia coli DNA molecule. We also provide evidence that electrostretched or migrated DNA under neutral microgel electrophoresis conditions is made up of individual chromosomes. Using the neutral microgel electrophoresis technique, DNA migration (stretching) was measured and the number of DNA double-strand breaks were counted following exposure of E. coli cells to 0, 12.5, 25, 50, or 100 rad of X-rays. The use of an intense fluorescent dye, YOYO and custom-made slides have helped us in visualizing individual bacterial DNA molecules. Bacterial DNA appears similar in structure compared to electrostretched DNA from human lymphocytes. We were able to detect changes in DNA migration (stretching) induced by an X-ray dose as low as 12.5 rad and an increase in the number of DNA breaks induced by a dose as low as 25 rad. The extent of DNA migration and number of breaks were directly correlated to X-ray dosage.
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Míguez-Burbano MJ, Jaramillo CA, Palmer CJ, Shor-Posner G, Velásquez LS, Lai H, Baum MK. Total immunoglobulin E levels and dengue infection on San Andrés Island, Colombia. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 1999; 6:624-6. [PMID: 10391876 PMCID: PMC95741 DOI: 10.1128/cdli.6.4.624-626.1999] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/1999] [Accepted: 04/26/1999] [Indexed: 11/20/2022]
Abstract
An evaluation of total immunoglobulin E (IgE) and dengue serostatus in 168 subjects from San Andrés Island, Colombia, revealed altered levels of IgE in 89% of the population. IgE levels were higher in patients with a history of dengue or with a current secondary or current primary infection than in subjects with no exposure (P = 0. 01). Dengue infection accounted for 23% of the variation in IgE levels.
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98
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Campa A, Shor-Posner G, Indacochea F, Zhang G, Lai H, Asthana D, Scott GB, Baum MK. Mortality risk in selenium-deficient HIV-positive children. JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES AND HUMAN RETROVIROLOGY : OFFICIAL PUBLICATION OF THE INTERNATIONAL RETROVIROLOGY ASSOCIATION 1999; 20:508-13. [PMID: 10225235 DOI: 10.1097/00042560-199904150-00015] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine the independent contribution of specific nutritional factors on disease progression and survival in HIV-1-infected children. POPULATION HIV-infected children (N = 24), who were perinatally exposed to the virus and symptomatic, were recruited between October and December of 1990 from the Jackson Memorial Pediatric Immunology Clinic, Miami, Florida, and observed for 5 years. METHODS Immune status was measured by CD4 cell count; nutritional status was determined using serum albumin and plasma trace elements including iron, zinc, and selenium. Cox proportional hazards regression models were used to evaluate the relationship of these parameters to survival. Use of antiretroviral treatment was considered in the statistical model, and age at death was considered a parameter of disease progression. RESULTS Over the course of the study, 12 children died of HIV-related causes. The final Cox multivariate analysis indicated that, of the variables evaluated, only CD4 cell count below 200 (risk ratio [RR] = 7.05; 95% confidence interval [CI], 1.87-26.5); p = .004], and low levels of plasma selenium (RR = 5.96; 95% CI, 1.32-26.81; p = .02) were significantly and independently related to mortality. Among the children who died, those with low selenium levels (< or =85 microg/L), died at a younger age, suggesting more rapid disease progression. CONCLUSIONS In pediatric HIV-infection, low plasma level of selenium is an independent predictor of mortality, and appears to be associated with faster disease progression.
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99
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Zhou Y, Yu C, Lai H. [Determination of active components in caoyiguang wettable powder by reversed-phase high performance liquid chromatography]. Se Pu 1999; 17:211-2. [PMID: 12549173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023] Open
Abstract
The Caoyiguang wettable powder is composed of two active components, synergists and other additives. The active components, bensulfuron methyl (Londax) and metolachlor (Dual), in 15.5% Caoyiguang wettable powder were determined by reversed phase high performance liquid chromatographic method simultaneously. The ZORBAX SB-C18 column (4.6 mm i.d. x 250 mm, 5 microns) and acidic mixture of methanol and water as mobile phase were used. The results showed that the recoveries were 98.1%-102.6%, and the coefficients of variation were 0.4%-0.8%. The method has been used to determine samples with satisfactory results.
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100
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Li K, Wong A, Li CK, Shing MM, Chik KW, Tsang KS, Lai H, Leung TF, Yuen PM. Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells in beta-thalassemia patients: kinetics of mobilization and composition of apheresis product. Exp Hematol 1999; 27:526-32. [PMID: 10089916 DOI: 10.1016/s0301-472x(98)00045-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
beta-Thalassemias are often associated with bone marrow expansion and immunomodulation in terms of lymphocyte subsets and cytokine levels in the peripheral blood. The mobilization of peripheral blood stem cells (PBSC) by cytokines in such a background has not been reported. If achieved, the apheresis product could be used as a stem cell back-up for beta-thalassemia patients prior to bone marrow transplant. PBSC collection may also become a means for providing stem and progenitor cells for gene manipulation and therapy of this disorder. The aim of the study was to assess the administration of G-CSF in mobilizing stem and progenitor cells in these patients and to compare the kinetics of CD34+ cells and lymphocyte subsets with those of healthy PBSC donors. Results showed that the CD34+ cells were effectively mobilized by G-CSF (10-16 micrograms/day per kg) in 20 thalassemia patients and 11 healthy donors. Although no significant difference was observed in levels of daily stem cell counts between the two groups of subjects, a 1 day delay in achieving peak levels of CD34+ cells was observed in the majority of thalassemia patients. The peak increase of CD34+ cells was 21.5 +/- 6.1-fold and 30.8 +/- 7.6-fold of the basal steady-state levels in thalassemia patients and healthy donors, respectively. Similar to the situation of healthy donors, G-CSF stimulated essentially the CD34+ cells and the myeloid lineage (granulocytes, monocytes) in thalassemia patients and had a slight effect on lymphocyte subsets (T-helper, T-suppressor, NK, and B cells) and activation (CD25, HLA-DR, and CD45RO). Compositions of the apheresis products, including CD34+CD38-, CD34+CD33+ and CD34+HLA-DR- cells, were similar in the two groups of subjects. Correlation studies showed that the level of CD34+ cells in the PB is a good indicator of that in the apheresis product (r = 0.88, p < 0.001). The study has demonstrated that under close monitoring of CD34+ cell levels in PB, the mobilization by G-CSF and collection of PBSC in beta-thalassemia patients are feasible.
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