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At least 145 records · Page 8Linked to original sources

PubMed1994

Responses of peripheral auditory neurons to two-tone stimuli during development: I. Correlation with frequency selectivity.

The responses of peripheral auditory neurons to two-tone stimuli were used to inferentially examine the nature of cochlear processing during development. Rate suppression was not seen in the youngest animals, and was first observed at 77 gestational days, in units exhibiting adultlike frequency selectivity. Suppression was highly correlated with the degree of tuning, and neurons were segregated into three classes based on these responses. Broadly tuned neurons (type IB) with low characteristic frequencies (CFs) did not exhibit suppression, and were observed early in postnatal life. Sharply tuned, but still immature neurons (type IS) exhibited suppression, but to a lesser degree than mature neurons (type M). One interpretation of these results is that basilar membrane mechanics are linear during the final stages of cochlear development, indicating that the immature signal transduction process is fundamentally different from that of adults.

Acoustic Stimulation↗

PubMed1988

Interleukin 2 production in patients with Chagas' disease: correlation with anti-parasite antibody responses.

Peripheral blood mononuclear cells (PBMC) isolated from chronic chagasic patients and control individuals in Recife, Brazil were examined for the ability to produce IL-2 in response to concanavalin A (Con A) stimulation. Overall, there was little difference in the range of the response (IL-2 production) between the chagasic and control groups. Within the chagasic group, however, there was a high negative correlation between IL-2 production and the level of anti-parasite antibody. This correlation is thought to be a reflection of the fact that individuals with more recent or more vigorous infections exhibit higher anti-parasite antibody responses but also display a greater degree of immunosuppression, as reflected in depressed IL-2 production.

Adult↗

PubMed1981

T-cell growth factor-mediated proliferation of lymphocytes from a T-chronic lymphocytic leukaemia patient lacking mitogen and alloantigen responsiveness.

Peripheral blood lymphocytes from a patient with chronic lymphocytic leukaemia of T cell origin (T-CLL PBL), were found to lack PHA and Con A responsiveness and to have a very poor responder activity in mixed lymphocyte cultures. In spite of the presence of Ia-like antigens on 36% of the T-CLL PBL, negligible stimulator capacity in MLC was observed. Proliferation of the T-CLL PBL could be induced and maintained both by exogenous T cell growth factor (TCGF) containing PHA, and mitogen-free TCGF. In addition, restoration of the responder and stimulator capacity in MLC was obtained in the presence of mitogen-free TCGF. These results indicate that the lack of response to mitogens and alloantigens of the T-CLL PBL has to be attributed to the failure of these cells to produce TCGF upon activation.

Adult↗

PubMed1991

Responsiveness of peripheral veins to vasodilators and the effect of nifedipine on alpha-adrenergic responsiveness in hypertension.

Vasodilators have varying hemodynamic properties that may be important in determining their efficacy for different disorders. We used the dorsal hand vein technique to measure the effects of several vasodilators infused locally and to measure the action of systemically administered nifedipine. The venodilatory effects of hydralazine, verapamil, diazoxide, and nitroglycerin were determined in peripheral veins of healthy subjects. The potency (ED50, the dose producing half-maximal response) was as follows: nitroglycerin (0.0007 micrograms/min) greater than verapamil (6.5 micrograms/min) greater than diazoxide (75 micrograms/min) greater than hydralazine (660 micrograms/min). The effect of oral nifedipine on alpha-adrenergic responsiveness of hand veins was determined. Nifedipine given in therapeutic doses for the treatment of hypertension was associated with a threefold increase in the ED50 for phenylephrine (92 to 277 ng/min; p less than 0.05) and norepinephrine (2.9 to 11.5 ng/min; p less than 0.05). Therapeutic doses of nifedipine are associated with measurable shifts in the dose-response curves to these two alpha-adrenergic agonists in the hand vein. The hand vein technique can be used not only to compare the potency of locally infused drugs but also to measure venous effects of vasoactive drugs at therapeutic concentrations achieved after systemic administration.

Adult↗

PubMed1993

Effect of polyadenylic.polyuridylic acid on cellular responses of peripheral blood mononuclear cells from patients with chronic active hepatitis B.

We have investigated in vitro proliferative responses of peripheral blood mononuclear cells and productions of interferon-gamma and soluble interleukin-2 receptors by these cells from 6 patients with chronic active hepatitis B immediately before and 24 hours after a single intravenous injection of 100 mg of polyadenylic.polyuridylic acid. Cell proliferations were assessed by the technique of tritiated-thymidine incorporation and productions of interferon-gamma and soluble interleukin-2 receptors were measured by enzyme-linked immunosorbent assay. The administration of polyadenylic.polyuridylic acid to the patients has resulted in significant increases of in vitro proliferations of their peripheral blood mononuclear cells as well as productions of interferon-gamma by these cells. However, in vitro productions of soluble interleukin-2 receptors were not changed significantly. These results suggest that the enhanced cellular responses by polyadenylic.polyuridylic acid might be due to the increased sensitivity rather than the increased expression of cellular interleukin-2 receptor.

Adult↗

PubMed1988

Human gingival Langerhans cells as accessory cells in mitogen induced T cell responses.

Peripheral blood and gingival tissue was collected from patients undergoing surgery for the treatment of periodontal disease. Both unfractionated peripheral blood mononuclear cells and a T cell-enriched, monocyte-depleted lymphocyte population were isolated from the blood samples while a gingival epithelial cell suspension was prepared from the oral aspect of the gingival tissue. The blood cells (1 X 10(5)) were then co-cultured with the gingival epithelial cells (1 X 10(5) and 1 X 10(4)) in 200 microliters aliquots in microtitre trays for three days to see if the epithelial cells could act as accessory cells in the lymphocyte response to the mitogen, phytohaemagglutinin (PHA). Lymphocyte proliferation was assessed by measuring the uptake of [6-3H] thymidine during the last 18 hours of culture. Removal of monocytes from peripheral blood mononuclear cells led to a significant, but not total, reduction in the proliferative response to PHA. When gingival epithelial cells were added to the T cells they restored their response to PHA in a dose dependent fashion. As Langerhans cells were the only potentially immunocompetent cells seen in the epithelial cell suspensions, it is concluded that these cells are acting as accessory cells in the T cell response to PHA.

Adult↗

PubMed1987

Effect of AVP on pressor responses to peripheral sympathetic stimulation in the rat.

Studies were carried out to determine whether arginine vasopressin (AVP) could modulate pressor responses to peripheral sympathetic stimulation or potentiate systemic norepinephrine (NE) vasoconstrictor effects. The effects of graded 30-min infusions of AVP (0.02, 0.2, and 2.0 ng X kg-1 X min-1) on the pressor responses to either electrical stimulation of spinal sympathetic outflow or NE injection (0.1, 0.5, and 1.0 micrograms/kg) were determined in central nervous system-ablated rats. Spinal stimulation with increasing frequency (0.25, 0.5, and 1.0 Hz, n = 8) at a constant voltage (20 V) or increasing voltage (8, 10, 15, and 20 V, n = 6) at a constant frequency (1 Hz) elicited significant stimulus-response relationships in mean arterial pressure (MAP). Similarly, NE increased MAP in a dose-related manner. AVP had no significant effect (P less than 0.05) on pressor responses to increasing frequency or voltage stimulation or to NE injection. We conclude that pressor responses to sympathetic stimulation in the rat are not modulated by actions of AVP to inhibit peripheral sympathetic ganglionic transmission or potentiate NE vasoconstrictor effects.

Animals↗

PubMed1997

Rats with decreased brain cholecystokinin levels show increased responsiveness to peripheral electrical stimulation-induced analgesia.

Using the P77PMC strain of rat, which is genetically prone to audiogenic seizures, and also has decreased levels of cholecystokinin (CCK), we examined the analgesic response to peripheral electrical stimulation, which is, in part, opiate-mediated. A number of studies have suggested that CCK may function as an antagonist to endogenous opiate effects. Therefore, we hypothesized that the P77PMC animals would show an enhanced analgesic response based on their decreased CCK levels producing a diminished endogenous opiate antagonism. We found that the analgesic effect on tail flick latency produced by 100 Hz peripheral electrical stimulation was more potent and longer lasting in P77PMC rats than in control rats. Moreover, the potency of the stimulation-produced analgesia correlated with the vulnerability to audiogenic seizures in these rats. We were able to block the peripheral electrical stimulation-induced analgesia (PSIA) using a cholecystokinin octapeptide (CCK-8) administered parenterally. Radioimmunoassay showed that the content of CCK-8 in cerebral cortex, hippocampus and periaqueductal gray was much lower in P77PMC rat than in controls. These results suggest that low CCK-8 content in the central nervous system of the P77PMC rats may be related to the high analgesic response to peripheral electrical stimulation, and further support the notion that CCK may be endogenous opiate antagonist.

Acoustic Stimulation↗

PubMed2000

Ethyleneglycol-bis-(beta-aminoethylether)tetraacetate as a blood anticoagulant: preservation of antigen-presenting cell function and antigen-specific proliferative response of peripheral blood mononuclear cells from stored blood.

We examined the progressive and irreversible loss of antigen-specific lymphoproliferative responses in peripheral blood mononuclear cells (PBMC) obtained from blood exposed for prolonged periods to EDTA as an anticoagulant. The responses of these lymphocytes to interleukin-2 or to concanavalin A were, however, unaffected. The observed loss was not due to depletion of metal ions by EDTA, since the addition of several divalent cations to whole blood during storage in EDTA or to lymphocytes from EDTA-stored blood during antigen stimulation in vitro did not alleviate the defect. Reconstitution of antigen-specific T-cell lines or Percoll-purified T cells with adherent antigen-presenting cells in antigen stimulation assays revealed that the presenting cells and not the effector T-cells were the targets of EDTA-mediated damage. The anticoagulant heparin helped to circumvent this problem. Surprisingly, EGTA, another metal ion chelator, could successfully replace EDTA, with a marginal loss in antigen-specific responses. Lymphoproliferative responses to antigens of Japanese encephalitis virus (JEV) and Mycobacterium tuberculosis were both significantly preserved in EGTA. JEV antigen-specific responses of PBMC obtained from the blood of convalescent JEV patients and stored in EGTA for as long as 24 h (n = 20) were comparable to those of fresh PBMC (n = 10), while PBMC from blood stored in EDTA (n = 17) for 16 h or longer failed to respond. We recommend that EGTA be used as the anticoagulant of choice for applications that require the lymphocyte proliferation assay, especially when on-site testing facilities are not available.

Antigen Presentation↗

PubMed1989

The role of cortisol in the peripheral granulocyte response to insulin-induced hypoglycaemia in man.

Peripheral blood leukocyte counts and plasma hormonal changes in response to acute insulin-induced hypoglycaemia were examined in 16 patients undergoing assessment of pituitary function. Eight subjects had a normal cortisol secretory response (Group 1), and 8 patients had definite hypopituitarism in whom the cortisol responses were deficient or absent (Group 2). An equivalent degree of hypoglycaemia was achieved in both groups. In Group 1a biphasic rise in leukocyte count occurred following hypoglycaemia, with an early rise in lymphocytes at 15 minutes after the acute hypoglycaemic reaction, and a later rise in granulocytes. A similar rise in lymphocytes was observed in Group 2, but the rise in the granulocyte count was attenuated, increasing from a basal value of 3.6 +/- 0.6 x 10(9) cells/L to a peak of 7.4 +/- 1.1 x 10(9) cells/L, compared with a peak of 11.7 +/- 1.2 x 10(9) cells/L in Group 1 (P less than 0.05). The usual increment in plasma cortisol in response to hypoglycaemia occurred in Group 1, but plasma cortisol did not rise in Group 2. A correlation was observed between the magnitude of the granulocyte rise and the increment in plasma cortisol in individual subjects (r = 0.64, P less than 0.02). This suggests that the rise in peripheral granulocytes following insulin-induced hypoglycaemia in man is mediated by cortisol released from the adrenal gland, following activation of the hypothalamic-pituitary-adrenal axis.

Blood Glucose↗

PubMed1987

Blastogenic response of peripheral blood lymphocytes from multiparous pregnant ewes.

The immunocompetence of pregnant multiparous ewes was investigated with respect to the blastogenic response of peripheral blood lymphocytes of (PBL) to three mitogens: PHA, Con A, and PWM. The profile of PBL responses shows 1) progressive suppression at 36 and 66 days of gestation, 2) enhanced response at 97 days of gestation, which approaches the mean values observed at the premating period, and 3) a redecline of the response at 137 days of gestation to depressed values lower than observed at 36 and 66 days of gestation. The results suggest that mitogen-treated lymphocytes were depressed and that the immunodepressive factor(s), which can influence lymphocytes at the systemic level, may be involved in the maintenance of the ovine fetal semiallograft.

Animals↗

PubMed1996

HPLC fractionated soluble egg antigen from Schistosoma mansoni elicits a heterogeneous human immune response.

Peripheral blood mononuclear cells (PBMC) from five chronic schistosomiasis patients, three former patients, a SEA sensitized individual, and normal controls were tested in lymphoblastogenesis assays for their ability to proliferate in response to soluble egg antigen (SEA) and soluble worm antigen preparation (SWAP) from Schistosoma mansoni. Cells from all patients and the SEA sensitized individual gave significantly higher responses than the normal controls when stimulated with SEA and SWAP. However, the chronic patients' SEA responses were much lower than those of the former patients and the SEA sensitized individual. When cells from the same donors were tested in the in vitro granuloma assay, all produced significant granulomatous responses except the normal controls. Once it was established that all individuals in the study gave significant lymphoproliferative responses and granulomatous reactions, SEA was subjected to HPLC fractionation to identify immunogenic protein components of SEA. HPLC separation yielded 25 major fractions. SEA responses from the sensitized individual and former patients exhibited broad, unregulated responsiveness including fractions with neutral, less charged proteins while the chronic patients demonstrated a more restricted range of responsiveness. SEA-HPLC fractions 14, 21, and 22 contain the most immunodominant proteins based on cellular proliferation data from reactive individuals tested.

Adolescent↗

PubMed1989

Proliferative response of peripheral blood mononuclear cells to autologous and allogeneic muscle in patients with polymyositis/dermatomyositis.

We examined the proliferative responses of peripheral blood mononuclear cells (PBMC) to autologous and homologous muscle homogenates in 21 patients with early, active, untreated polymyositis/dermatomyositis (PM/DM), 8 patients with chronic PM/DM, 10 patients with myopathies other than PM/DM, 7 patients with connective tissue diseases without myositis, and 12 healthy individuals. PBMC from patients with PM/DM and from control subjects were incubated with various dilutions of autologous and homologous muscle homogenates. PBMC from patients with active PM/DM underwent significant proliferation on exposure to both the autologous muscle and the homologous muscle homogenates. In contrast, PBMC from patients with chronic PM/DM, other myopathies, connective tissue diseases without myositis, and from healthy individuals did not respond to either autologous or homologous muscle. Our findings demonstrate that the PBMC of patients with PM/DM are sensitized to muscle.

Adolescent↗

PubMed1999

Patients with obstructive sleep apnea have an abnormal peripheral vascular response to hypoxia.

Patients with obstructive sleep apnea (OSA) have been reported to have an augmented pressor response to hypoxic rebreathing. To assess the contribution of the peripheral vasculature to this hemodynamic response, we measured heart rate, mean arterial pressure (MAP), and forearm blood flow by venous occlusion plethysmography in 13 patients with OSA and in 6 nonapneic control subjects at arterial oxygen saturations (Sa(O(2))) of 90, 85, and 80% during progressive isocapnic hypoxia. Measurements were also performed during recovery from 5 min of forearm ischemia induced with cuff occlusion. MAP increased similarly in both groups during hypoxia (mean increase at 80% Sa(O(2)): OSA patients, 9 +/- 11 mmHg; controls, 12 +/- 7 mmHg). Forearm vascular resistance, calculated from forearm blood flow and MAP, decreased in controls (mean change -37 +/- 19% at Sa(O(2)) 80%) but not in patients (mean change -4 +/- 16% at 80% Sa(O(2))). Both groups decreased forearm vascular resistance similarly after forearm ischemia (maximum change from baseline -85%). We conclude that OSA patients have an abnormal peripheral vascular response to isocapnic hypoxia.

Adult↗

PubMed1990

Effect of Mycobacterium leprae's phenolic glycolipid-I on interferon-gamma augmentation of monocyte oxidative responses.

Peripheral blood monocytes were pretreated with phenolic glycolipid-I (PGL-I), dimycocerosyl phthiocerol (DIM), or mycoside A, then cultured in the presence or absence of interferon-gamma (IFN-gamma). Their oxidative responses to Mycobacterium leprae, phorbol myristate acetate (PMA), and opsonized zymosan were evaluated. In response to M. leprae, monocytes pretreated with PGL-I released less O2- than nonlipid-treated control cells. The IFN-gamma augmentation of oxidative responses was suppressed only when in PGL-I-pretreated monocytes and only when the stimulus was M. leprae. This suggests that PGL-I, by affecting the IFN-gamma enhancement of phagocytic cell oxidative responses, aids further the intracellular survival of M. leprae.

Antigens, Bacterial↗

PubMed1989

[Peripheral circulatory responses during dental treatment under local anesthesia. Comparison between plethysmogram and ultrasonic Doppler blood flow].

In this study, peripheral circulatory responses during dental treatment under local anesthesia were observed. Changes in hemodynamics data, ECG, systolic blood pressure (SBP), diastolic blood pressure (DBP), digital and ear-lobe plethysmogram (PT), and radials and external carotid artery ultrasonic doppler blood flow (FW) were recorded by means of a multipurpose monitoring system. An improved fixed probe was devised for the purpose of stabilizing the external carotid artery FW record, and the ear-piece facebow system (Hanau, No. 153) was remodeled. Radial FW index D/S1 and external carotid FW index d/S1 were analyzed to determine systolic velocity S1 and diastolic velocity D or d. Pressure tests and cold stimulation tests were performed as fundamental research. Comparative investigations were made of changes in PT and FW in the light of SBP, DBP and heart rate (HR). A total of 71 instances of dental treatment was performed on 25 non-hypertensive patients (N-HT) and 25 patients with essential hypertension (HT). The patients were divided into 2 groups according to the local anesthetic employed: the E group, to whom 1:80,000 epinephrine with an addition of 2% lidocaine was administered, and the NE group, to whom 1:25,000 norepinephrine was administered. Results and conclusions 1. When peripheral blood flow was interrupted during the pressure test, digital PT and radial FW were disappeared. 2. Digital PT, radial diastolic FW D, and index D/S1 decreased greatly as a result of the cold stimulation test. It was suggested that changes in digital PT accord with the diastolic velocity D of radial FW. 3. At the stage of local anesthesia, SBP rose most in the HT-NE group. There was a tendency for digital PT and radial FW D either to decrease or to increase. It was assumed that cardio-stroke volume increased when PT and FW increased. Decreases in digital PT and radial FW apparently indicate increased capillary resistance. 4. Greatest increases in HR at the stage of local anesthesia occurred in the N-HT-E group. Digital PT and radial FW D tended to decrease. In cases of increased HR, PT and FW tended to decrease. In comparison with conditions immediately before treatment, digital PT and radial FW D decreased more in the N-HT group than in the HT group.

Anesthesia, Dental↗

PubMed2000

Impaired responses of peripheral blood mononuclear cells to staphylococcal superantigen in patients with severe atopic dermatitis: a role of T cell apoptosis.

Staphylococcus aureus colonization is an almost universal feature of atopic dermatitis. In order to investigate the role of staphylococcal enterotoxin B in the pathogenesis of atopic dermatitis, we assessed the correlation between clinical disease severity and proliferative response of peripheral blood mononuclear cells to staphylococcal enterotoxin B in patients with atopic dermatitis. Peripheral blood mononuclear cells from patients with mild atopic dermatitis showed significantly increased proliferative responses to staphylococcal enterotoxin B compared to controls. In contrast, peripheral blood mononuclear cells from patients with severe atopic dermatitis showed markedly suppressed proliferative responses. Additionally, longitudinal evaluation of peripheral blood mononuclear cell samples from the same patient demonstrated that proliferative responses were suppressed only at times of severe disease exacerbation. Mixing experiments, using autologous T cells and antigen presenting cells that were isolated at different time points from the same patient, demonstrated that T cells of severe atopic dermatitis patients were dysfunctional, but their antigen presenting cell function remained intact. We found no significant differences of interleukin-2 levels in the culture supernatants between healthy controls and atopic dermatitis groups. Fluorescence-activated cell sorter analysis for APO2.7 antigen, an early apoptosis cell marker, demonstrated that approximately 60% of staphylococcal-enterotoxin-B-stimulated T cells expressed APO2.7 antigen in severe atopic dermatitis cases. By contrast, 5%-20% of T cells expressed APO2.7 after staphylococcal enterotoxin B stimulation in cases of mild atopic dermatitis and in healthy controls. Nuclear staining with Hoechst 33258 also showed approximately 40% apoptotic cells in the CD19-CD16-PBMC of severe atopic dermatitis patients, compared with only 5%-10% in the mild atopic dermatitis group and in healthy controls. Blocking monoclonal antibody to Fas ligand partially prevented the staphylococcal-enterotoxin-B-induced apoptosis detected by APO2.7 expression and Hoechst 33258 staining. Suppressed proliferation of peripheral blood mononuclear cells in severe atopic dermatitis patients may be secondary to T cell death by apoptosis. These results suggest that an infection of S. aureus producing staphylococcal enterotoxin B may play a role in aggravation of atopic dermatitis by inducing apoptosis in T cells.

Adult↗

PubMed2001

The peripheral vascular response to exercise is impaired in patients with risk factors for coronary artery disease.

BACKGROUND: Abnormal coronary and brachial artery responses have been described in individuals with risk factors for coronary artery disease (CAD). Peripheral arterial tonometry (PAT), a newly developed digital plethysmographic technique was used to assess peripheral vascular response to exercise in healthy controls and individuals with risk factors. METHODS AND RESULTS: Continuous finger PAT during Bruce protocol exercise test was performed in 30 subjects with risk factors for CAD and 30 healthy individuals. Compared with baseline, the PAT wave amplitude at peak exercise decreased in the subjects but increased in the controls: 83 +/- 28% vs. 114 +/- 40% respectively, p < 0.01. CONCLUSIONS: A different pattern of systemic vascular response to exercise was found in individuals with risk factors for atherosclerosis. Since the vascular behavior in these patients is probably related to endothelial dysfunction, it may be that peripheral arterial tonometry can be used as a simple, readily available technique to assess endothelial function.

Adult↗