Biomedical subjects

J He

Publications and source records attributed to J He.

At least 235 records · Page 13Linked to original sources

PubMed1998

Sister chromatid exchange and micronucleus frequency in human lymphocytes of 1,650 subjects in an Italian population: II. Contribution of sex, age, and lifestyle.

Sister chromatid exchange (SCE) and micronuclei (MN) analysis was carried out on 1,650 healthy individuals living in Pisa and in two nearby small cities, Cascina and Navacchio (Ca-Na). The effect of smoking on SCEs was linearly correlated with the number of cigarettes per day, and an increase of 7.3% SCEs was detectable for as few cigarettes as 1-10/day. Ex-smokers showed intermediate mean values of SCEs (8.09 +/- 1.88) in comparison with never smokers (7.54 +/- 1.61) and current smokers (8.45 +/- 1.94). Mean values of SCEs of ex-smokers decreased linearly with time of smoking cessation, reaching the mean values of never smokers within 8 years. The extent of SCE decrease was inversely proportional to the number of cigarettes previously smoked. No interaction between smoking habits and coffee or alcohol drinking on SCEs was observed. A borderline (P = 0.053) increase in mean SCE values in coffee drinkers (more than 3 cups/day) was found. The age effect on SCEs was remarkable in Ca-Na, but not in Pisa donors. Job type was not associated with significant modification of mean values of SCEs. Multiple logistic regression analysis revealed a statistically significant association between the proportion of high frequency cells (HCF) outliers and coffee consumption. Age and sex appeared to be by far the most important variables associated with modifications in MN frequency, which increased by 0.04 per thousand and 0.02 per thousand per year in males and females, respectively. Children and young donors (age < or = 40 years) showed lower MN frequency regardless of sex, whereas sex appeared to determine a significantly higher increase of MN only in females older than 40 years. In contrast, in males the MN rate by age tended to level off after the age of 30-50. MN frequencies of Pisa blue- and white-collar workers were statistically significantly higher than in students (+0.71 and +0.55 per thousand, respectively). Smoking did not determine any increase of MN frequency. A total lack of correlation (P = 0.913) between MN and SCEs was observed.

Adolescent↗

PubMed1998

Transduction of recombinant human erythropoietin receptor cDNA into daughter progenitors derived from single CD34(3+) cord blood cells changes the differentiation profile of daughter progenitors.

In this study, we tested the capacity to change the differentiation profile of progenitor cells by retroviral-mediated transduction of EpoR cDNA into one of the paired daughter cells derived from single CD34(3+) CB cells. Our results show that for the non-viral-treated daughter cells, the majority (99.6%) formed the same colony type. However, with cells transduced with viral vectors, 7.1% of the daughter cells transduced with the EpoR cDNA formed either a burst forming unit-erythroid (BFU-E) or a colony-forming unit-granulocyte, macrophage, erythroid, megakaryocyte (CFU-GEMM) colony compared to the other daughter cell transduced with viral supernatant lacking EpoR cDNA, which formed either a colony-forming unit granulocyte-macrophage (CFU-GM) or a high proliferative potential-colony forming cell (HPP-CFC) colony. Expression of the transduced EpoR cDNA was confirmed in individual colonies by RT-PCR analysis. These results substantiate in a more rigorous fashion our previous results that it is possible to change the Epo-responsive differentiation profile of progenitor cells by transduction into these cells of an EpoR cDNA and this change was apparent only in daughter cells derived from single CD34(3+) kit+ cells transduced with EpoR cDNA.

Antigens, CD↗

PubMed1998

Chemokine receptors in HIV-1 infection of the central nervous system.

Several members of the chemokine receptor are used as coreceptors for HIV-1 infection in the central nervous system (CNS). CCR5 and CCR3 are coreceptors together with CD4 for HIV-1 infection of microglia, the major target for HIV-1 infection in the CNS. Microglia express CXCR4, but their infection by HIV-1 viruses that use only CXCR4 as a coreceptor is relatively inefficient. CXCR4 is also expressed in subpopulations of neurons that are resistant to HIV-1 infection. Additional orphan chemokine receptors that can mediate HIV-1 or SIV entry are expressed in the brain or neurally-derived cell lines, but their role in CNS infection has not been defined. The pattern of chemokine receptor expression in the brain is likely to determine the tropism of HIV-1 for particular CNS target cells and to impact inflammatory and degenerative mechanisms associated with CNS infection.

AIDS Dementia Complex↗

PubMed1998

Downregulation of right ventricular phosphodiesterase PDE-3A mRNA and protein before the development of canine heart failure.

Phosphodiesterase III (PDE-3) inhibitors are inotropes used to treat congestive heart failure (HF). Previous studies showed PDE-3A mRNA levels were reduced in the left ventricle (LV) in dogs subjected to pacing-induced HF. The present study evaluated a time-course for RV-specific changes in PDE-3A mRNAs and proteins after pacing for 3 wk (n = 4) or in HF (4-5 wk; n = 4-6). Total RNA from LV/RV tissues was isolated for Northern analyses; cytosolic and microsomal proteins were prepared for PDE-3A immunoblots. PDE-3A mRNAs (7-8 and 10 kb) were normalized against glyceraldehyde-3-phosphodehydrogenase (GAPDH) or ribosomal 18s with similar results. PDE-3A/GAPDH ratios in 3 wk were unchanged in LV, but significantly (p < 0.05) reduced by 48% in RV vs unpaced controls (n = 8). In contrast, PDE-3A (7-8 kb)/GAPDH ratios were significantly reduced in HF by 50-59% in both ventricles. Consistent with mRNA levels, significant reductions in microsomal 135 kDa (93-96%) and cytosolic 120 kDa PDE-3A (57-69%) were seen in both ventricles in HF or in the RV at 3 wk; an LV-specific reduction (50%) in cytosolic 80 kDa PDE-3A in HF was also detected. In summary, RV-specific downregulation of PDE-3A mRNA/protein(s) at 3 wk suggests that hemodynamic rather than humoral mechanisms are responsible, and provides a molecular basis for the limited efficacy of milrinone in the progression of HF.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1998

Atmospheric mercury deposition on Fanjing Mountain Nature Reserve, Guizhou, China.

Fanjing Mountain Nature Reserve (FMNR) is surrounded with several Hg emission sources within distances of 100-200 km. At the two sites studied, Tongren and Danzai, Hg emission and deposition fluxes, Hg concentration in the air, soil and other samples are all several hundred times higher than at other relatively clean areas. Hg accumulation in soil and moss at FMNR varies with the sampling heights. Total Hg deposition to this area has been estimated to be 115 micrograms m-2 y-1 using moss bag technique. Dry deposition was determined to be about 5.2 micrograms m-2 month-1 during March to June, corresponding to more than 50% of the total deposition.

Air Pollutants, Occupational↗

PubMed1998

Long-latency neurons in auditory cortex involved in temporal integration: theoretical analysis of experimental data.

A previous experimental study (He et al., 1997) found 132 duration-selective neurons with long latencies of greater than 30 ms in the dorsal zone of cat auditory cortex. The mechanism by which such long-latency neurons integrate information during their latent period is investigated by analysis of the temporal relationship between the stimulus and neuronal response. In the present study, we developed a one-layer perceptron to examine the above temporal relationship of the experimental results. The acoustic stimulus was represented as a contiguous series of sequential short time epochs. The perceptron was trained by using the spike data as the desired outputs and the acoustic stimuli (in digital format) as the inputs. The adaptive weights between the outputs and the inputs after training indicated the temporal relationship between neuronal responses and the stimuli. The contribution of each time epoch of the stimulus could be either positive or negative: the positive contribution corresponds to excitatory input and the negative contribution to inhibitory input. Long-duration-selective neurons were found to receive mainly excitatory input along the entire effective stimulus duration. However, duration-tuned neurons received excitatory input for only the time period from the stimulus onset to their best durations, and inhibitory thereafter. The temporal integration pattern of short-duration-selective neurons was similar to duration-tuned neurons. However, short-duration-selective neurons received excitatory input only at the beginning of the stimulus. Each of the duration-threshold neurons integrated auditory information only for a restricted time period of the stimulus, suggesting that they have a time window over the stimulus time domain. Non-duration-threshold neurons have time windows extending from the stimulus onset onward. The assembly of duration-threshold neurons and non-duration-threshold neurons may collectively represent the time axis of the stimulus.

Acoustic Stimulation↗

PubMed1998

Indirect laser photoacoustic detection for trace samples on membranes.

An indirect laser photoacoustic technique is described. The basic principle, the experimental set-up and the influencing factors are discussed in detail. This method was used to quantify phenylamine, arginine and methylene blue on membranes. The linear ranges of the calibration curve are up to two orders of magnitude. With 1 microliter of sample solution, the detection limits are 0.25, 1.52 and 0.14 pmol for phenylamine, arginine and methylene blue, respectively.

Absorption↗

PubMed1998

Effects of pre-exposure of mouse testis with low-dose (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation.

PURPOSE: To investigate the effects of pre-exposure of mouse testis with low-doses of (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation. MATERIALS AND METHODS: Testes of the B6C3F1 hybrid strain mice were pre-irradiated with 0.05 Gy of (16)O8+ ions or 60Co gamma-rays and then after 4 h given a test irradiation with 2 Gy of the same radiation type. SOD activity and thiobarbituric acid reactive substances (TBARS) in the testes were determined by spectrophotometric and TBA methods respectively at 4 h after irradiation. Testis weight, sperm count and sperm morphology were analysed at day 35 after irradiation. RESULTS: Compared with controls, there was a significant increase in SOD activity and a significant decrease in TBARS level of pretreated testes. Testis weight loss, sperm count reduction and sperm abnormalities were significantly lower in the pretreated testes. The bioeffects of a 2 Gy dose of (16)O8+ ions relative to 60Co gamma-rays were 1.84 +/- 0.28 for testis weight, 1.22 +/- 0.25 for sperm count and 1.29 +/- 0.10 for sperm abnormalities. CONCLUSIONS: These data suggest that pre-exposure of testes with a low dose of heavy ions or gamma-rays renders the organ more resistant to subsequent high-dose irradiation. The increase of SOD activity and the decrease of lipid peroxidation levels induced by low-dose ionizing irradiation may be involved in this resistance. The effects with heavy ion irradiation were greater than with gamma-rays.

Animals↗

PubMed1998

Seroprevalence of human herpesvirus 8 among Zambian women of childbearing age without Kaposi's sarcoma (KS) and mother-child pairs with KS.

The seroprevalence of human herpesvirus 8 (HHV-8) among a group of Zambian women of reproductive age and among mother-child pairs in which either one of them has Kaposi's sarcoma (KS) was determined. A cross-sectional group of 378 pregnant women was randomly recruited into the study, and 183 (48.4%) had HHV-8 antibodies. Among the human immunodeficiency virus (HIV)-1-infected women, 51.1% were HHV-8-seropositive, whereas of HIV-1-negative women, 47.3% were HHV-8-seropositive. In addition, 21 women index patients with KS and 5 young children index patients with KS were studied. All children with KS had mothers who were HHV-8-seropositive, while not all children whose mothers had KS were infected with HHV-8. Our study suggests that there is a high HHV-8 seroprevalence among Zambian women, and the rate is almost the same in HIV-1-positive and -negative women. This high seroprevalence may be a contributing factor toward the increased frequency of KS in this population.

Adolescent↗

PubMed1998

Stretch reflex sensitivity: effects of postural and muscle length changes.

In this study, a combination of clinical evaluation, laboratory testing, and model simulation of spasticity is performed under various postural conditions to investigate the changes in the sensitivity and specific mechanisms of spasticity. Fifty-nine multiple sclerosis patients participated in the study and received spasticity evaluation based on both the Ashworth scale and the pendulum test. Spasticity was found to increase in the pendulum test when the subjects were tested in a supine posture, compared to when they were sitting. Three patterns of stretch reflex response were seen for similar leg swing trajectories. While it was clear that the increased stretch of rectus femoris in the supine posture contributed to the increased spasticity, the results of modeling showed that other more complex factors were also involved. The supraspinal descending modulation associated with postural control may play a more dominant role in the severity of spasticity. The results suggest that the biomechanical test of spasticity should be performed for several different postures or ranges of movement with muscle activities monitored simultaneously, so that the effect of various factors can be examined. The work also indicates that a neuromusculoskeletal model with detailed muscle dynamics and stretch reflex loops is a valuable tool for investigating the neural mechanisms of spasticity.

Adult↗

PubMed1998

Coactivation to reduce variability in the elderly.

The aim of this experiment was to determine whether elderly persons exhibit reciprocal phasing of muscle activity and scale EMG burst amplitude in the same manner as young people. Seven young and 7 elderly adults performed 30( elbow flexion movements at 800 ms duration to a visual target against varying inertial loads. The elderly were not able to achieve the required movement duration as frequently and spent a greater portion of the movement accelerating than the young. The young and the elderly subjects scaled EMG burst amplitude to the increasing loads in the same fashion, although the elderly subjects coactivated the agonist/antagonist muscles more than did the young subjects and thus did not accelerate the limb as rapidly. We hypothesized that the elderly used coactivation to reduce movement variability, and we developed a single-joint model with two muscles to examine this hypothesis. The model simulation correctly predicted the variability reduction due to coactivation. It appears, however, that this reduces the capability to accelerate rapidly.

Adult↗

PubMed1998

Afferent and efferent connections of nucleus praeeminentialis in the channel catfish: a reevaluation.

Nucleus praeeminentialis (nPr) is an isthmic nucleus that has been described in the brains of electrosensory teleost fishes and a single non-electrosensory species. The nucleus receives axon collaterals of ascending medullary sensory lemniscal neurons. Axons of nPr neurons project in turn back down onto those same populations of medullary projection neurons via a descending parallel fiber system (the molecular layer or cerebellar crest). Thus nPr forms a link in a sensory feedback loop that modulates the activity of neurons that relay information from medulla to midbrain. The purpose of this study is to investigate the nature of the afferent and efferent connections of the nPr with the specific aim of investigating other sources of input into this modulatory circuit. Transport of neuronal tracers (horseradish peroxidase, DiI and dextran amines) revealed that nPr has extensive interconnections with nuclei in the basal metencephalon, cerebellum, octavolateralis column and basal medulla. A previously described source of afference, the torus semicircularis in the mesencephalon, was not indicated by our studies. Our studies suggest that in addition to regulating the sensitivity and resolution of electrosensory and mechanosensory lateral line systems, the nPr may play a role in the resolution of signal ambiguities posed by auditory or vestibular stimulation of the saccular endorgan of the inner ear.

Afferent Pathways↗

PubMed1998

Seven-year incidence of hypertension in a cohort of middle-aged African Americans and whites.

Many studies have suggested that African Americans have a higher prevalence of hypertension than whites. The authors conducted a prospective study of hypertension incidence from 1987-1988 to 1994-1995 in 140 African American and 237 white adults aged 30 to 54 years at baseline. The study participants were screened for participation in the Trials of Hypertension Prevention, phase 1, an 18-month lifestyle modification intervention trial aimed at lowering blood pressure, at the Baltimore Clinical Center. Baseline age, blood pressure, body mass index, and heart rate were similar in the two groups. Compared with whites, however, African Americans had a lower percentage of men, college graduates, and households with an income > or = $40,000 per year. African Americans also had lower mean urinary sodium to creatinine ratio and potassium to creatinine ratio, but a similar sodium to potassium ratio. The incidence of hypertension (blood pressure > or = 160/95 mm Hg and/or taking antihypertensive medication) over 7 years of follow-up was nearly identical: 25.7% in African Americans and 25.3% in whites. Baseline age, gender, blood pressure, and heart rate were all associated with the incidence of hypertension. Even after adjustment for these covariables, the risk of hypertension was not higher in African Americans compared with whites. These results indicate that middle-aged African Americans and whites have a similar risk of developing hypertension given the same age, initial blood pressure, and body mass index at baseline.

Adult↗

PubMed1998

Effect of uteroplacental insufficiency upon brain neuropeptide Y and corticotropin-releasing factor gene expression and concentrations.

Various hypothalamic functions such as feeding behavior, energy expenditure, body weight gain, level of anxiety, and sexual maturation are mediated by a balance between the concentrations of neuropeptide Y (NPY) and corticotropin-releasing factor (CRF). To test the hypothesis that maternal uteroplacental insufficiency alters the offspring's brain NPY and/or CRF levels, we examined the effect of maternal uterine artery ligation with intrauterine growth restriction (IUGR) (p < 0.05) upon fetal (20 d) and postnatal (4, 14, and 21 d) brain NPY and CRF synthesis, concentrations, and regional distribution. An age-related increase in NPY (0.8 kb) and CRF (1.4 kb) mRNA levels with peak amounts at the 14-d postnatal age (p < 0.05) was observed. IUGR was associated with a 75% increase in fetal brain NPY mRNA levels (p < 0.05) with no change in NPY peptide, CRF mRNA and peptide amounts. Although the increase in NPY mRNA levels persisted postnatally (p < 0.05) at d 4 and 21, CRF mRNA amounts were 2.5-fold higher only in the 4-d IUGR (p < 0.05). Paralleling the mRNA changes, an age-related increase in RIA of NPY and CRF peptide concentrations was noted (p < 0.05). IUGR caused postnatal brain NPY and CRF peptide changes similar to corresponding mRNA levels (p < 0.05), despite normal postnatal circulating glucose, insulin, corticosterone, and leptin concentrations. The age-specific intergroup differences in the NPY and CRF peptide immunoreactivity appeared predominantly in the hypothalamic region. We conclude that maternal uteroplacental insufficiency causing IUGR leads to a pretranslational imbalance in the immediate (4 d) postnatal brain NPY and CRF peptide concentrations, thereby altering the developmental pattern. This alteration in NPY and CRF peptide concentrations, despite normalization of the metabolic milieu was associated with a persistent diminution in body weight. The IUGR-associated pretranslational increase in NPY and not CRF peptide levels at d 21, may herald changes in feeding behavior during the postsuckling phase.

Animals↗

PubMed1998

HIV-1 strain-associated variability in infection of primary neuroglia.

Qualitative differences among strains of Human Immunodeficiency Virus type 1 (HIV-1) may influence viral infectivity for cells of the central nervous system (CNS) and determine or at least significantly influence the neuropathogenesis of brain infection. In this study, we compared infectivity for these cells in vitro among several different laboratory-adapted HIV-1 strains differing in cellular tropism. These strains included three lymphotropic strains (SF2, NL4-3, and SG3.1), two macrophage-tropic strains (SF128A, SF162), and one brain-derived strain (YU2). In microglia, macrophage-tropic strain SF128A established productive infection while the lymphotropic strain SF2 did not. In infected astrocytes, all HIV-1 strains transiently produced variable and much lower levels of p24 antigen. Viral DNA env or tat gene sequences were amplified from infected astrocytes; the amplified signals varied among HIV-1 strains, but the strongest viral DNA signals were obtained from cells infected by the lymphotropic strains SF2 and SG3.1. Transfection of astrocytes with infectious HIV-1 proviral DNA clones confirmed the observation that HIV-1 strains differ in their ability to replicate in astrocytes. Transfection revealed post-entry blocks to replication by macrophage-tropic proviruses pSF128A and pSF162. However, cytomegalovirus (CMV) superinfection of transfected astrocytes enhanced p24 production by lymphotropic HIV-1 proviruses twofold and stimulated p24 production by the otherwise inactive macrophage-tropic proviruses. This study demonstrates the spectrum of HIV-1 strain-associated variation in infectivity for neuroglia, and suggests, in addition, that herpesviral factors or viral-induced cellular factors may stimulate HIV-1 infection in astrocytes and expand the neural cell tropism of certain HIV-1 strains.

Cells, Cultured↗

PubMed1998

Cytomegalovirus and human herpesvirus-6 trans-activate the HIV-1 long terminal repeat via multiple response regions in human fetal astrocytes.

Cytomegalovirus (CMV) and human herpesvirus-6 (HHV-6) infection stimulated HIV-1 replication and trans-activated the HIV-1 promoter (the long terminal repeat or LTR) to a similar extent in transfected, nonimmortalized, human fetal astrocytes. CMV infection increased basal LTR expression by approximately sevenfold, while HHV-6 infection increased basal LTR expression by fourfold. This enhancing effect required cell-cell contact between CMV-infected or HHV-6-infected and LTR-containing cells. To determine the target regions on the HIV promoter that respond to CMV and HHV-6 trans-activation, several modified LTR-reporter gene constructs were tested. Loss of functional NFkappaB, Sp1, or upstream modulatory sites on the LTR caused significant reduction ofbasal LTR expression in astrocytes. These elements also mediated the trans-activation events during HHV-6 or CMV infection in astrocytes, though to varying degrees. Electrophoretic mobility shift assays (EMSA) indicated that core, enhancer, and upstream modulatory regions of the LTR interacted specifically with nuclear proteins from both uninfected and CMV- or HHV-6-infected human fetal astrocytes. CMV or HHV-6 infection did not appear to induce unique, LTR-specific nuclear binding proteins, but rather enhanced the relative proportion of some of the existing protein complexes, in particular, the complexes formed with the AP-1 binding sites on the HIV-1 LTR (nt - 354 to - 316). Our data suggest that CMV or HHV-6 trans-activation of HIV LTR activity in human fetal astrocytes proceeds via intracellular molecular interactions involving herpesviral gene products, cellular proteins, and multiple sites on the LTR upstream of the TATA box. The pattern of LTR activity in astrocytes suggests that host cell factors modulating HIV expression may differ from those dominant in T-cells or immortalized astroglia, and this could contribute to differences in the astrocyte's ability to support HIV replication.

Astrocytes↗

PubMed1998

Hepatitis E virus infection in eastern India.

Most cases of enterically transmitted non-A, non-B hepatitis in India have so far been attributed to hepatitis E virus (HEV) infection. Most of the documented studies of hepatitis have focused on the incidence of this disease in northern, western, and south central India. A small seroprevalence study was conducted in the eastern Indian city of Patna to assess the degree of HEV infection among acute sporadic hepatitis cases. Forty-two percent (24 of 57) of the cases of acute sporadic hepatitis were positive for anti-HEV antibodies. Absence of any serologic markers of hepatitis A, B, or E in 58% (33 of 57) of the cases with symptoms of acute hepatitis suggest that there may be as yet unidentified enterically transmitted viruses in this area.

Adult↗

PubMed1998

[Epidemiologic features of viral hepatitis in Fujian].

To study the prevalence and the epidemiologic features of viral hepatitis in Fujian, a seroepidemiological survey on five kinds of viral hepatitis infection has been carried out in Fujian province since 1992. Using stratified mulitistage random cluster sampling, 3,809 serum samples were collected from 1,237 families in general population in the disease surveillance points in Fujian province. HBsAg, anti-HBs and anti-HBc were screened by RIA and HBeAg, anti-HAV, anti-HCV anti-HDV anti-HEV were by EIA. The results showed that the standardized prevalence rates of HAV, HBV, HCV, HDV, HEV, HBsAg, anti-HBs, anti-HBc and HBeAg were 76.60%, 77.26%, 3.99%, 2.10%, 18.80%, 17.25%, 34.33%, 68.58% and 8.42% respectively. The HAV, HBV, HEV prevalence rates in rural were higher than in urban areas. The HBsAg prevalence rate among males was higher than females, with peaks evidenced in 5-9 years old and 20-29 years old. There seemed to be significant family clusterings of HBV and HEV infection. There was higher HEV prevalence rate among the young-robusts but lower HAV prevalence rate among children in urban areas. These results suggested that Fujian is a highly prevalent area for HAV, HBV, HCV and HEV infections. Thus HA and HB vaccination should play as the most effective strategy in the prevention of HAV and HBV infections.

Adolescent↗