Biomedical subjects

R Fei

Publications and source records attributed to R Fei.

10 recordsLinked to original sources

PubMed2000

Hemispheric interaction, metacontrol, and mnemonic processing in split-brain macaques.

These experiments explored the interactions remaining between the cerebral hemispheres in two split-brain macaques. The 'split' was earlier confirmed by showing that one hemisphere was incapable of identifying visual images seen by the other. The critical tests for residual interactions were intermingled with control trials in a continuous recognition task. These tests were of two kinds: 'parallel processing', to determine how simultaneous viewing by both hemispheres affected subsequent recognition by one of them alone; and 'conflict', where opposite responses were demanded from the two hemispheres, thus assessing the issue of metacontrol. Two types of stimuli were also employed: ART, in which each hemisphere saw essentially the same image; and BIPARTITE, in which images were entirely different for each hemisphere. Since, with either type of stimulus, performance was best when viewed by both hemispheres at both encoding and retrieval, 'parallel processing' was highly efficient. However, when both hemispheres viewed initially and only one was subsequently queried, performance was significantly worse than when each hemisphere acted alone on each occasion. It is thus reasoned that when both hemisphere view together, the resultant memory trace somehow reflects the bilaterality, a conclusion concordant with observations of Marcel on blindsight. Processing different images (BIPARTITE) was somewhat more disruptive in this regard than if the same image was viewed by each hemisphere. This was particularly true in the conflict situation, where for one hemisphere the item seen was NEW and for the other it was OLD. A response of 'OLD' was, at first, consistently rewarded. When this well-established protocol was changed, the hemispheres in each animal were gradually able to revise their joint behavior. This, together with the effect of disparate images, and the deficiency evoked when the animals were forced to recognize unilaterally an image first viewed under bilateral conditions, all manifest considerable, and complex, interaction between the hemispheres despite absence of the forebrain commissures. The superior colliculus seems a likely focal point for such interhemispheric effects.

Animals↗

PubMed1999

Long-term reversal of hemispheric specialization for visual memory in a split-brain macaque.

Accuracy of response and pattern of ocular fixations in three split-brain macaques were used to evaluate performance of each hemisphere in a continuous visual recognition task. The animal indicated by ocular fixation upon response points whether a displayed image or face was 'NEW' or 'OLD'. An inadvertent lesion of cingulate gyrus severely reduced contralateral fixations and impaired performance of the affected hemisphere in one animal, confirming the inferred relation between hemisphere and laterality of fixations. The hemispheres in the other two animals were initially remarkably similar in accuracy with human faces and with images; but the right hemisphere was significantly superior to the left for macaque faces. Parallel to this, in the one animal tested while simultaneously using both eyes/hemispheres, fixations were made primarily on the left half of human and macaque faces (right hemispheric control), whereas for images the ocular fixations were predominantly focused on the right half. However, after further, extensive training the left hemisphere performed with significantly greater accuracy than the right on all material and this shift was accompanied and further corroborated by a reversal of the fixational pattern to favor the right half of faces, as continued to be the case with images. Thus, over the long term both the pattern of ocular fixations and the accuracy of performance demonstrate a migration from right to left hemispheric dominance as familiarity with the task increased. Performance of the initially superior hemisphere actually diminished with this shift, presenting a uniquely puzzling question of hemispheric balance in the absence of the forebrain commissures.

Animals↗

PubMed1999

Development of a universal immunoenzyme quantitative assay for detecting amplified products of nucleic acid and its preliminary application in hepatitis C virus.

OBJECTIVE: To develop a universal quantitative immunoenzyme assay (EIA) for detecting amplified products of nucleic acid and its application in hepatitis C virus (HCV). METHODS: The appropriate cycle number of amplification was selected to stop polymerase chain reaction (PCR) before the "plateau stage". At the same time, primers HCV (3) of the second PCR were modified with biotin so that the amplified products were labeled. The products were diluted and subsequently added to the streptavidin-coated wells, and the biotinylated products were captured, followed by denaturation of NaOH, and non-biotinylated strands were removed. Hybridization was performed by adding the specific probe labeled with fluorescein. Finally antifluorescein horse radish peroxidase (HRP) conjugates were added, after washing, 3, 3', 5, 5',-tetramethylbenzidine (TMB) was added to the wells and then measured on a microplate reader. RESULTS: EIA detection of amplified products of HCV showed that this assay was rapid, sensitive, specific and accurate. Correlation between the initial number of viral template and the EIA of amplified products was good. We also prospectively investigated the response to interferon in five patients with HCV coinfection. Results showed that this assay could be used as a guidance to the clinical therapy in directing the use of antiviral drugs. CONCLUSIONS: This assay could be widely used as a universal technique for the quantitative detection of amplified products of all nucleic acid (such as virus, bacterium) and other human genes (such as HLA B27), it has vast vistas.

Hepacivirus↗

PubMed1998

Analysis of low-speed rotational atherectomy for the reduction of platelet aggregation.

Platelet activation is an important determinant of acute outcomes of percutaneous intervention. The objective of this study was to assess the effect of rotational atherectomy on platelet activation in an in vitro model. Freshly collected heparinized porcine blood was exposed to a 2.0-mm Rotablator burr rotating at one of three speeds: 180,000, 140,000, or 0 rpm. The specimens were analyzed immediately for concentration and size of platelet aggregates and plasma-free hemoglobin. There were significantly more platelet aggregates of >20-microm diameter at higher speeds (7,434+/-2,193 at 180,000, vs. 2,269+/-627 at 140,000, vs. 633+/-258 aggregates/ml at 0 rpm; P < 0.001). Plasma-free hemoglobin, a simple measure of cell damage, decreased with decreasing rotational speed (429+/-168 mg/dl at 180,000, vs. 88+/-44 mg/dl at 140,000, vs. 9+/-9 mg/dl at 0 rpm; P < 0.0001). In vitro, platelet activation decreases with decreasing burr speed, suggesting that the use of the Rotablator system at its minimum approved speed (140,000 rpm) could prove clinically beneficial.

Animals↗

PubMed1998

Experimental hypersensitivity pneumonitis: location of transferring cells.

Cultured cells from Micropolyspora faeni-sensitized donors can adoptively transfer murine experimental hypersensitivity pneumonitis (EHP). We sought to determine the location of transferred cells in recipient animals, the influence of the origin of the cultured cells, and the effect of specific intratracheal challenge. We labeled cultured sensitized spleen or lung-associated lymph node (LALN) cells with CFDA-SE, a cytoplasmic stain, before transfer to naive recipients, which were sacrificed 1 h, 1 day, or 4 days thereafter. We also transferred labeled cultured spleen cells to recipients that were challenged with intratracheal M. faeni and sacrificed 4 days later (MF). Controls were recipients of M. faeni-sensitized and cultured cells challenged with intratracheal normal saline (NS) and recipients of ovalbumin (OVA)-sensitized cells cultured with M. faeni and challenged with intratracheal M. faeni (OVA). The number and proportion of cells that were stained were determined in dispersed spleen, peripheral and lung-associated lymph nodes, and lung parenchyma. The extent of the pulmonary inflammatory response was measured by determining the proportion of microscopic fields that were abnormal and the total number of dispersed pulmonary cells. CFDA-SE stained cells uniformly, and stained cells could be detected in recipients for up to 7 days after transfer. CFDA-SE treatment (0.5 microM) did not affect the ability of cells to transfer EHP adoptively. Transferred cells could be detected easily in lung, lung-associated and peripheral lymph nodes, blood, and spleen. Transferred cells localized to the lung at 1 h but then rapidly decreased with no difference between labeled cells from spleen and LALN. After intratracheal M. faeni challenge, there was no difference in the proportion of labeled cells in the lung among any of the groups (MF, NS, or OVA). There was an increase in the number of lung cells in the MF group compared with the control (NS and OVA) groups. We conclude that cells capable of transfer are transiently (1 h) trapped in the lung but are much decreased in the lung by four days after transfer. After intratracheal antigen challenge of recipients, there is a substantial increase in the number of pulmonary cells in animals exhibiting adoptive EHP but not in the control groups. Transferred cells responsible for EHP are increased in the lungs of animals with adoptive EHP.

Adoptive Transfer↗

PubMed1997

Mid-Infrared Diode Laser Spectroscopy of X ; 1 A ' HC35 Cl

The observation of the C-Cl stretching fundamental of HC35 Cl in its ground X ; 1 A ' state is reported. HCCl was formed in a continuous flow system by the excimer laser photolysis of CHBr2 Cl at 193 nm and the transient absorption recorded by infrared diode laser spectroscopy. The band has a -type character and the fundamental vibrational frequency is found to be 811.5963 cm-1 . No evidence was found for perturbations in either the ground or vibrationally excited states, implying that the excited triplet a 3 A " states lies above the C-Cl stretching level in HCCl. The observed rotation-vibration transitions were well fit by a standard asymmetric rotor Hamiltonian. There is a decrease in the A rotational constant on vibrational excitation, suggesting that some bend-C-Cl stretch coupling is present.

Journal Article↗

PubMed1995

Experimental hypersensitivity pneumonitis: in vitro effects of interleukin-2 and interferon-gamma.

Cultured CD4+ cells are responsible for transfer of adoptive murine experimental hypersensitivity pneumonitis (EHP) (ARRD 1992; 146:1582-8). To characterize interactions that occur in vitro that result in cells able to transfer EHP, we added either antibody to IFN-gamma, antibody to IL-2, or 30 or 300 micrograms/ml IFN-gamma at the onset of 72-hour culture of C3H/HeJ spleen cells from either M. faeni or ovalbumin (control) sensitized donors with 30 micrograms/ml Micropolyspora faeni. We determined the phenotype of cells after culture and the amount of IL-2 or IFN-gamma in the culture supernatants, transferred cells to naive recipients, challenged the recipients intratracheally with M. faeni, and determined the extent of pulmonary inflammatory changes 4 days thereafter. Substantial amounts of IL-2 and IFN-gamma were detected in supernatants of cultures from M. faeni-sensitized animals, and lesser amounts were detected in culture supernatants from ovalbumin-sensitized donors. Treatment of cultures of M. faeni-sensitized cells with antibody to IL-2 or IFN-gamma blocked or reduced measurable IL-2 or IFN-gamma for the duration of culture. Treatment with IFN-gamma blocked increased levels of IL-2 at 48 and 72 hours of culture. Cultured M. faeni-sensitized cells adoptively transfer EHP. Cells from cultures depleted of either IL-2 or IFN-gamma or supplemented with IFN-gamma could transfer EHP equally well. We conclude that in vitro maturation of cells capable of adoptive EHP is not dependent on soluble IL-2 or IFN-gamma and is not altered by exogenous IFN-gamma.

Alveolitis, Extrinsic Allergic↗

PubMed1994

Isolation and ex vivo expansion of CD34+ cells from cord blood using dextran sedimentation and avidin column selection.

Human umbilical cord bloods were fractionated by unit gravity sedimentation in 1% (v/v) dextran, followed by immunoaffinity selection for CD34+ stem and progenitor cells. Dextran sedimentation alone enabled recovery of more than 80% of the nucleated cells present and 90% of the CD34+ cells, as determined by flow cytometry. The addition of an immunoaffinity selection step for CD34+ cells resulted in a 134-fold enrichment for CD34+ cells, with a mean yield of 64 +/- 15%. The resultant CD34+ population contained almost half the CFU-GM activity initially present in the cord bloods and could be expanded ex vivo in liquid culture.

Antigens, CD↗

PubMed1994

Influence of pressure- and flow-triggered synchronous intermittent mandatory ventilation on inspiratory muscle work.

OBJECTIVE: To determine the effect of pressure- and flow-triggered synchronous intermittent mandatory ventilation on inspiratory muscle work. DESIGN: Consecutive clinical, prospective, randomized trial. SETTING: Medical intensive care unit (ICU) of a U.S. Veterans Affairs Medical Center. PATIENTS: Eight patients recovering from acute respiratory failure of various etiologies. INTERVENTIONS: Assist control, followed by randomized application of pressure- and flow-triggered synchronous intermittent mandatory ventilation at 60%, 40%, 20% of the assist-control rate, and flow-triggered continuous positive airway pressure. A total of eight settings were maintained for 10 mins each. MEASUREMENTS AND MAIN RESULTS: Total work rate (joules/min), inspiratory muscle work (joules/L), and pressure time-product per breath (cm H2O-sec) were measured. During pressure- or flow-triggered synchronous intermittent mandatory ventilation, total work rate increased as the mandatory rate was decreased. The method of ventilator triggering had a significant effect on the total work rate. With pressure-triggered synchronous intermittent mandatory ventilation, the total work rate at 60% of the assist-control rate was similar to that with assist-control; whereas with flow-triggered synchronous intermittent mandatory ventilation, this result was achieved at 40% of the assist-control rate. At a machine support level of 20%, total work rate with pressure-triggered synchronous intermittent mandatory ventilation was significantly greater than with flow-triggered synchronous intermittent mandatory ventilation. The method of ventilator triggering had no significant effect on the inspiratory muscle work of the mandatory breaths. This finding was in contrast to the effect on inspiratory muscle work of spontaneous breaths. With pressure-triggered synchronous intermittent mandatory ventilation, inspiratory muscle work of the spontaneous breaths was greater than with the flow-triggered at machine support of 40% and 20%. With either pressure- or flow-triggered synchronous intermittent mandatory ventilation, inspiratory muscle work of the mandatory breaths was not significantly different from that of the corresponding spontaneous breaths, except at the lower machine support levels with the pressure-triggered synchronous intermittent mandatory ventilation. Pressure-time product followed a trend similar to that of inspiratory muscle work. CONCLUSIONS: During synchronous intermittent mandatory ventilation, the method of ventilator triggering has a significant effect on the total work rate and inspiratory muscle work of the spontaneous breaths, particularly at lower machine support levels. Conversely, the method of ventilator triggering has no significant effect on inspiratory muscle work of the mandatory breaths.

Acute Disease↗

PubMed1982

Kinetic studies of haemopoietic progenitor cells (CFU-C) and T-lymphocytes in the liver of human foetus.

In the development of human foetus, liver is an important haemopoietic organ. We have determined the liver weight and total hepatic nucleated cells from 24 foetuses on the one hand, and CFU-C yield, total number of CFU-C and T-lymphocytes in liver from 22 foetuses of different ages on the other. From the kinetic observations through the early developmental period of the foetuses, the maximum yield of CFU-C or the total number of CFU-C in the liver occurs at 4-5 months of gestation; during the first 5 months of gestation the percentage of T-lymphocytes in the liver is about 1-2%.

Cells, Cultured↗