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At least 127 records · Page 7Linked to original sources
PubMed2006

Alterations in the maternal peripheral microvascular response in pregnancies complicated by preeclampsia and the impact of fetal sex.

OBJECTIVE: Peripheral microvascular function is altered in preeclampsia (PE). Recent studies suggest that maternal physiology varies with fetal sex. We wanted to examine if there were sex-specific differences in maternal peripheral microvascular function in normal pregnancy and pregnancy complicated by PE. METHODS: Peripheral microvascular responses were examined using the noninvasive technique of laser Doppler flowmetry in normotensive healthy pregnant women and in women diagnosed with PE. We measured baseline perfusion, response to thermal hyperemia, post-occlusive reperfusion, and vasodilatation in response to corticotropin-releasing hormone (CRH), a potent vasodilator in human skin. RESULTS: At 31 to 40 weeks' gestation those women with a male fetus exhibited increased vasodilatation in response to CRH (P <.05) and greater baseline perfusion (P <.05) than those pregnant with a female fetus. PE women pregnant with a male fetus demonstrated a significantly reduced vasodilatation in response to CRH (P <.05), reduced baseline perfusion (P <.05), and reduced response to thermal hyperemia (P <.05) compared to normotensive women pregnant with a male fetus. Microvascular function was not significantly different between preeclamptic and normotensive women with a female fetus. CONCLUSION: These data show that there are differences in maternal peripheral microvascular function in relation to fetal sex.

Adolescent↗
PubMed2001

Effect of cervical vagotomy on sympathetic nerve responses to peripheral interleukin-1beta.

Although the vagus nerve is an important neural pathway mediating immune-to-brain communication, the role of the vagus in mediating sympathetic nerve discharge (SND) responses to peripheral cytokines is not well established. In the present study we determined renal, interscapular brown adipose tissue (IBAT), splenic, and lumbar SND responses before and for 60 min after the intravenous administration of interleukin-1beta (IL-1beta, 100 ng) in chloralose-anesthetized, sham-vagotomized and cervical-vagotomized (bilateral) rats. In sham-vagotomized rats, IL-1beta administration increased (P<0.05) splenic and lumbar SND while renal and IBAT SND remained unchanged from control levels. Renal, splenic, and lumbar SND were increased (P<0.05) whereas IBAT SND remained unchanged from control after IL-1beta in vagotomized rats. Renal, splenic, and lumbar SND responses were significantly higher after IL-1beta in vagotomized compared with sham-vagotomized rats. These results demonstrate that regionally-selective SND (renal, splenic, and lumbar) responses to IL-1beta can occur in the absence of the vagus nerve and suggest that the vagus nerve provides a tonic inhibition to the discharges in these nerves in response to peripheral IL-1beta.

Adipose Tissue, Brown↗
PubMed1988

Dynamic response of peripheral chemoreflex loop to changes in end-tidal CO2.

The dynamic ventilatory response of the peripheral chemoreflex loop after isoxic step changes in end-tidal PCO2 (PETCO2) (range 5-30 Torr) was studied in 12 alpha-chloralose-urethan-anesthetized cats. The technique of artificial brain stem perfusion allowed the response to be observed in isolation from the central chemoreflex loop. The data were fitted by an exponential with time delay. During normoxia the mean time constant and time delay (with SD) were 8.6 +/- 7.3 and 3.3 +/- 0.9 s, respectively (9 cats, 56 runs). During hypoxia [arterial PO2 (PaO2) approximately 60 Torr] these values were 6.0 +/- 4.5 and 2.9 +/- 0.9 s (6 cats, 38 runs). In 17 of the 94 runs an augmented breath occurred in the first three breaths after the stepwise increase in PETCO2. For these augmented breaths, tidal volume, inspiratory time, and expiratory time were not different from the next augmented breath occurring in the same run in the steady state. Neither a rate-sensitive component nor a central neural mechanism (central afterdischarge), with the property of maintaining an increased but slowly declining respiratory activity for some minutes after cessation of the PETCO2 challenge, was found. We conclude that the description of the ventilatory response of the peripheral chemoreflex loop to step changes in PETCO2 with a single exponential and time delay is adequate.

Animals↗
PubMed1992

Myocardial and peripheral vascular responses to behavioral challenges and their stability in black and white Americans.

The purpose of this study was to assess the short term stability of myocardial and peripheral vascular responses to behavioral challenges, and to compare the response patterns of Black and White men. Blood pressure and heart rate, as well as stroke volume, cardiac output, total peripheral resistance, and systolic time interval measures derived from the impedance cardiogram were obtained in 12 Black and 12 White men. These measures were taken prior to and during an evaluative speech stressor, a mirror star tracing task, and a forehead cold pressor test presented during two laboratory sessions scheduled two weeks apart. In general, total peripheral resistance and impedance-derived baseline measures showed acceptable reproducibility (G greater than .85). With a few exceptions, adequate reliability was also demonstrated for change (delta) scores. All tasks raised blood pressure responses above resting levels. Blacks demonstrated significantly greater increases in total peripheral resistance responses across tasks. Whites but not Blacks also revealed increases above baseline in cardiac output and contractility as estimated by the Heather Index. These findings are consistent with the view that Blacks show greater vascular responsiveness than Whites across a variety of tasks, but reveal less myocardial responsiveness.

Adult↗
PubMed1977

Aortocoronary vein graft flow in response to peripheral venous administration of sodium nitroprusside or diazepam.

Vein graft flow (VGF) in response to peripheral venous administration of sodium nitroprusside (SNP) or diazepam was studied in 13 anesthetized patients following cardiopulmonary bypass for aortocoronary vein bypass graft operations. SNP (0.5 microgram/kg/min) significantly reduced mean arterial pressure (p less than 0.05). VGF paralleled the decreased blood pressure, but the reduction was not significant (p greater than 0.05). Diazepam (0.1 mg/kg) did not significantly alter blood pressure or VGF. We conclude that peripheral venous administration of SNP or diazepam is not a pharmacologically reliable method by which to increase VGF in the period immediately following a graft operation.

Blood Pressure↗
PubMed1992

Impaired proliferative responses of peripheral blood B cells from splenectomized subjects to phorbol ester and ionophore.

The responses of peripheral blood B cells to mitogenic stimulation were examined in 12 splenectomized subjects without residual splenic function, as determined by pitted erythrocyte counts. These were compared to a group of healthy controls matched for age and sex. Polyclonal anti-immunoglobulin evoked a normal transient elevation in intracellular free Ca2+ in splenectomized subjects, thereby suggesting that the early events of the signal transduction pathway are not impaired. However, mitogenic stimulation by pre-treatment with phorbol ester and culture in presence of a calcium ionophore (Ionomycin) resulted in reduced uptake of 3H-thymidine and subsequent proliferation. Nevertheless, entry into the mitotic cycle, as assessed by expression of Ki67, was slightly, but not significantly impaired. Unlike in normal controls, where up to 7% of freshly-isolated B cells were Ki67+, almost no Ki67+ peripheral B cells were observed in splenectomized subjects. The data are consistent with the hypothesis that peripheral B cells in splenectomized subjects are in a reduced state of activation compared with normal controls and require additional growth factor stimulation before they can undergo mitosis.

Adolescent↗
PubMed1994

Response of peripheral blood mononuclear cells to mitogenic stimulation in young calves.

Sixteen Holstein bull calves were used to evaluate effects of increasing blood BHBA, as a consequence of ruminal development, on response of peripheral blood mononuclear cells to mitogenic stimulation. Calves were blocked by date of birth and assigned to weaning at 35 or 49 d of the study. Calves began the study at 4 d of age. Milk replacer was fed at 10% of BW to d 7 prior to weaning; thereafter, milk replacer offered was reduced by 50%. Calf starter was offered from d 1. Blood was sampled at wk 0, 2, 4, 6, 8, and 10 at 4 h after the a.m. feeding. Blood glucose declined, and blood BHBA increased, as calf starter intake increased. Blood BHBA increased at weaning in each treatment group and exceeded 1 mM during the week of weaning. Responses of peripheral blood mononuclear cells to stimulation with concanavalin A, pokeweed mitogen, or phytohemagglutinin were unaffected by increasing blood BHBA and increased with age. Increased concentration of blood BHBA in young calves from increased starter intake did not impair immune response.

3-Hydroxybutyric Acid↗
PubMed2000

Central control of cardiac baroreflex responses during peripheral hyperosmolality.

Acute increases in peripheral osmolality evoke a pressor response and baroreflex-mediated bradycardia. These experiments were designed to determine if the fall in heart rate during peripheral sodium loading is 1) equivalent to bradycardia accompanying phenylephrine (PE) infusion, 2) mediated by the parasympathetic (PSNS) or sympathetic (SNS) nervous system, and 3) controlled by the median preoptic nucleus (MnPO). Male rats received an intravenous infusion of isotonic saline, hypertonic saline (2.5 M NaCl), or PE for 30 min. Blood pressure increased equivalently in the hypertonic NaCl and PE groups. However, heart rate fell more in animals infused with PE. Furthermore, pretreatment with methylatropine to block the PSNS had no effect on bradycardia, whereas blocking SNS influences on cardiac function significantly attenuated the fall in heart rate during peripheral hyperosmolality. Finally, kainic acid administration in the MnPO before testing increased bradycardia observed during hypertonic saline loading. Taken together, these data suggest that acute peripheral hyperosmolality acts at the MnPO to reduce cardiac SNS withdrawal during the pressor response that reduces the associated baroreflex bradycardia.

Adrenergic beta-Antagonists↗
PubMed1995

Alterations in pallidal neuronal responses to peripheral sensory and striatal stimulation in symptomatic and recovered parkinsonian cats.

The spontaneous activity, responses to peripheral sensory and ipsilateral caudate nucleus stimulation of globus pallidus (GP) and entopeduncular nucleus (ENTO) neurons were studied in cats while normal, symptomatic for 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced parkinsonism, and when spontaneously recovered from gross parkinsonian motor deficits. Administration of MPTP resulted in parkinsonian motor symptoms that spontaneously recovered approximately 4-6 weeks after the MPTP administration. Post-mortem dopamine levels in recovered animals was approximately 95% below levels previously measured in normal animals. In symptomatic animals, the mean spontaneous firing rate for GP units was decreased by 50% and increased by 55% for ENTO units recorded. Spontaneous firing rates for GP and ENTO units in recovered cats were not significantly different from those observed in normal cats. In normal cats, 31.4% of GP and 29% of ENTO units tested responded to tactile stimulation of the face. Only 12.2% of GP and 13% of ENTO units responded to such stimulation in parkinsonian animals while the responses were generally less specific (larger receptive fields, more bilateral receptive fields, and more responses to multiple stimulation types) than normal. In recovered cats GP and ENTO responses resembled those observed in normal cats. There was no difference in the overall percentage of pallidal units responding to striatal stimulation across the 3 experimental conditions. There was, however, an increase in the percentage of units responding with complex response sequences (i.e. decrease in activity followed by an increase in activity) in symptomatic animals as compared to normal and recovered animals. The results suggest that loss of striatal dopamine in parkinsonian animals has profound effects on the sensory responsiveness of GP and ENTO neurons and that these effects coincide with the appearance of and recovery from parkinsonian motor deficits. These data further support the notion that sensory information processing by the basal ganglia may play an important role in influencing motor output.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1989

Comparison of the acute renal and peripheral vascular responses to frusemide and bumetanide at low and high dose.

1. The effects of equipotent doses of frusemide (10 mg and 100 mg) and bumetanide (250 micrograms and 2.5 mg) upon renal and peripheral vascular responses, urinary prostaglandin excretion, plasma renin activity, angiotensin II and noradrenaline were compared in nine healthy volunteers. 2. Frusemide (10 mg and 100 mg) and bumetanide (2.5 mg) increased renal blood flow acutely compared with placebo but bumetanide (250 micrograms) had no effect. The changes in peripheral vascular responses were not significantly different from placebo. 3. Urinary prostaglandin metabolite excretion was acutely increased by all treatments, with no inter-treatment difference. Plasma renin activity was increased acutely by both doses of frusemide and by bumetanide (2.5 mg) compared with placebo and to bumetanide (250 micrograms). There were no differences between the latter two treatments. Angiotensin II was increased significantly 30 min after frusemide 100 mg and bumetanide 2.5 mg, and by all four treatments at 50 min when compared with placebo. There were no significant differences between either of the low doses or the higher doses. Plasma noradrenaline was unchanged by all treatments. 4. Frusemide 100 mg and bumetanide 2.5 mg have the same effects on the renal vasculature and the renin-angiotensin-prostaglandin system. Under the conditions of this study, frusemide 10 mg had different effects on plasma renin activity than bumetanide 250 micrograms.

Adult↗
PubMed2001

[Analysis of unusual late responses of peripheral nerves].

F-waves are routinely evaluated in nerve conduction studies on proximal peripheral nerves. However, unusual late responses other than F-waves that show variation in latency and configuration sometimes confound evaluation of the F-waves. The unusual late responses were analyzed in this study. In two patients with cervical radiculopathy, two patients with brachial plexus injury and 9 patients with polyneuropathy, A-waves showing constant latency and configuration were recorded in addition to temporally dispersed F-waves. The A-waves in these patients persisted after supramaximal stimulation of the peripheral nerves, although the A-waves should normally disappear in response to supramaximal stimulation. The supramaximally stimulated A-waves were prominent in polyneuropathy and nerve lesions with demyelinating pathology. A patient with Guillain-Barré syndrome showed unusual repetitive discharges that might be important electrodiagnostic findings in the early stage of illness. In patients with myotonic dystrophy, electrical stimulation elicited repetitive discharges that continued from the M-waves. Recordings with a concentric needle electrode showed characteristics similar to those of myotonic discharges recorded during needle electrode insertion. When the repetitive discharges were mild, the F-waves were recorded. Absence of the F-waves in myotonic dystrophy might be related to the myotonic discharges elicited by electrical stimulation, and may not imply impaired conduction of the peripheral nerves. A patient with myokymia showed repetitive discharges with constant configuration but variable latency, although the F-waves were normal. These repetitive discharges may be evoked by ephaptic transmission resulting from abnormal excitability of the peripheral nerves or muscles of different etiologies.

Adolescent↗
PubMed1988

Peripheral vascular responses to hyperthermia in the rat.

To investigate the sequence and nature of the peripheral vascular responses during the prodromal period of heat stroke, rats were implanted with Doppler flow probes on the superior mesenteric (SMA), left iliac (LIA) or left renal (LRA), and external caudal (ECA) arteries. Studies were performed in unanesthetized rats (n = 6) exposed to 46 degrees C and in chloralose-anesthetized animals (n = 11) at 40 degrees C. Core (Tc) and tail-skin temperatures, heart rate, and mean arterial blood pressure (MAP) were also monitored. In both groups, prolonged (70-150 min) exposure progressively elevated Tc from 37.0 to 44.0 degrees C. MAP rose to a plateau then fell precipitously as Tc exceeded 41.5 degrees C. SMA resistance increased throughout the early stages of heating, with a sharp decline from this elevated level 10-15 min before the precipitous fall in MAP. ECA resistance fell initially but increased in the terminal stage of heating. In unanesthetized animals, LIA resistance progressively declined. In chloralose-anesthetized animals LRA resistance rose progressively, then increased markedly as Tc exceeded 41.5 degrees C. These data support the hypothesis that a selective loss of compensatory splanchnic vasoconstriction may trigger the cascade of events that characterize heat stroke. This differential vascular response was similar in both unanesthetized and anesthetized animals.

Animals↗
PubMed1982

Variation in mitogen-induced ovine lymphocyte blastogenesis: adherent cells or 2-mercaptoethanol restore randomly depressed responses.

Peripheral blood leucocytes (PBL) isolated 23 times over a 6-week period from four normal sheep showed considerable variation in serially tested responses to predetermined optimal concentrations of concanavalin A (Con A), phytohaemagglutinin (PHA), and pokeweed mitogen (PWM). Con A responses, in particular, varied widely and were often randomly depressed (21 of 91 times compared to 15 of 91 times for PHA or PWM). The addition of as few as 1% adherent cells (AC) to depressed cultures fully restored the PBL proliferative response to normal levels. Addition of greater numbers of AC (5 or 10%) had little further enhancing effect on depressed cultures. The addition of 1, 5, or 10% AC to cultures that were responding at normal levels increased responses only slightly. Autologous or allogeneic AC were equally effective. Addition of 2-mercaptoethanol (2-ME) to depressed cultures only partially restored the blastogenic response to Con A and had little effect on normal cultures.

Animals↗
PubMedDate not supplied

[Assessment of the response of peripheral blood mononuclear leukocytes on Helicobacter pylori infection in children].

In the study the proliferative response of peripheral blood mononuclear leukocytes (PBML) from children with chronic dyspepsia (chr. d) to H.p. antigens was investigated. From 38 children aged 7-18, with chr. d., blood was collected just before upper GI endoscopy. Twenty one patients were found to be H.p. (+). PBML were used for the cultures and were stimulated with heat-killed H.p. G27 bacteria, heated and unheated glycine extract (GE) of H.p. G27 or with H.p. LPS containing Lewis X and Lewis Y determinants, in the presence or absence IL-2. The cell proliferation was estimated on the basis of [3H] - thymidine incorporation. In the cultures, the phenotype of responding cells was determined by an EIA with monoclonal antibody to human CD3, CD4 and CD8. PBML from patients H.p. (-), responded to killed H.p. bacteria and to heated GE more frequently and more intensively than PBML from the H.p.(+). IL-2 enhanced PBML response to these antigens. Unheated GE did not induce PBML proliferation even in the cultures with IL-2. LPS alone induced proliferation of PBML from 3 patients (2 H.p. - and 1 H.p.+). However, in the presence of IL-2, LPS induced proliferation of PBML from 15 patients. In the cultures of PBML stimulated with whole bacteria or heated EG, T cells dominated. In the cultures of PBML from H.p. (+) we found a higher percentage of CD8 cells in comparison with the cultures of PBML from H.p. (-). Data demonstrate a significant variation in the response of PBML from dyspeptic children to H.p. antigens.

Adolescent↗
PubMed1988

Dietary potassium, blood pressure and peripheral adrenergic responsiveness in the deoxycorticosterone acetate-salt rat.

This study investigated the effect of 6 weeks of dietary potassium (K) supplementation on blood pressure and in vivo and in vitro peripheral adrenergic responsiveness in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Dietary K supplementation did not affect the development of hypertension in DOCA-salt rats. The chronotropic and dipsogenic responses to isoproterenol (ISO) administration were significantly decreased in DOCA-salt rats. Addition of K to the diet resulted in a complete normalization of both of these responses so that they were similar to controls. Aortic smooth muscle from DOCA-salt rats exhibited a significant reduction in the relaxation response to ISO. Dietary K supplementation resulted in only a partial normalization of this response. Enhanced norepinephrine responsiveness was observed in aortic smooth muscle from DOCA-salt rats, but was not affected by dietary K supplementation. These results show that: 1) a 0.5% dietary K supplementation in DOCA-salt rats does not prevent the development of hypertension, 2) the decreased peripheral beta-adrenergic responsiveness observed in DOCA-salt rats is partially normalized by the addition of K to the diet, and 3) the increased alpha- adrenergic sensitivity is not affected by the 0.5% dietary K supplementation in the DOCA-salt rat. It is concluded that dietary K supplementation has differential effects on peripheral alpha- and beta- adrenergic responsiveness in the DOCA-salt rat. These actions may be related to the lack of an antihypertensive effect of K in the present study.

Animals↗
PubMed1996

Spinal cord NMDA receptors modulate peripheral immune responses and spinal cord c-fos expression after immune challenge in rats subjected to unilateral mononeuropathy.

To characterize further the neural involvement in local immune reactions, we evaluated the effect of intrathecal NMDA-receptor blocker dizocilpine maleate (MK-801) on the peripheral immune response itself and on spinal cord c-fos expression induced by the delayed-type hypersensitivity (DTH) response. Immune challenge took place in the hind paw ipsilateral or contralateral to an injured sciatic nerve in both previously sensitized and immune-naive animals. An enhanced immune response was observed bilaterally in the hind paws of animals subjected to unilateral mononeuropathy compared with sham-operated controls. In contrast, no such enhancement was observed when neuropathic animals were challenged in the front paws. The increased DTH response was blocked successfully by the intrathecal administration of an analgesic dose of MK-801. Compared with sham-operated animals, animals subjected to unilateral mononeuropathy showed both a differential distribution and an increase in the number of c-fos-labeled neurons in the dorsal horn of the L3-L5 spinal cord segments after immune challenge. This was observed irrespective of whether the challenge took place ipsilateral or contralateral to the injured nerve. In addition to reversing the changes in immune response, intrathecal administration of MK-801 reversed the pattern of c-fos immunoreactivity in the spinal cord after immune challenge in neuropathic animals. These data suggest that select groups of spinal cord neurons participate in enhancing the peripheral immune response to a specific antigen in neuropathic animals and that this enhancement involves central NMDA receptors.

Animals↗
PubMed1998

Disease stage related in vitro responsiveness of peripheral blood T-lymphocytes in patients with head and neck carcinoma.

The in vitro responsiveness of peripheral blood mononuclear cells (PBMC) T lymphocytes was studied in 81 patients with limited or extended head and neck squamous cell carcinoma (HNSCC), as judged by T, N and T + N stages. Patients included in the study were males below 80 years of age, without auto-immune disease or cachexia, who were not taking any immuno-active medication at the time of diagnosis. The patients were divided into groups according to TNM stage T0-2 vs T3-4, N0-1 vs N2-3 or T + N0-3 vs T + N4-7. When cells from patients with early and late stage, according to T, N or T + N stage, were compared, we found a decreased level of mitogen stimulated T-cells and decreased spontaneous proliferation with increasing disease stage. The same was true if the in vitro mitogenesis of T-cells was analysed separately, depending on the laryngeal or oral cavity/pharyngeal origin of the patients' tumours. If the patients were divided into two groups based on N stage, decreased gamma-interferon, and to some extent interleukin (IL-2), but not IL-4 levels, were found to be related to the disease stage.

Aged↗