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PubMed1981

Macrophage T cell interaction in man: binding of antigen-specific human proliferating and helper T cells to antigen-pulsed macrophages.

Adsorption of T cells over monolayers of autologous, but not allogeneic, macrophages (M phi) pulsed with tetanus toxoid (TT) antigen resulted in the specific depletion of the capacity of the T cells to proliferate and to release T cell helper factor in response to stimulation, with TT antigen. T cells that bound to the TT-pulsed M phi monolayers were specifically enriched in their capacity to proliferate in response to TT. Turkey antiserum to the human B cell glycoprotein p 29,34, but not turkey antiserum to human beta 2 microglobulin, inhibited the binding of TT-reactive T cells to TT-pulsed M phi. This inhibition resulted from the binding of the anti-p 29,34 antiserum to DR determinants expressed on the surface of the M phi. Immunosorbent purified IgG anti-TT, added in great excess, did not inhibit the binding of TT-reactive T cells to TT-pulsed M phi monolayers. Soluble TT antigen and rabbit antiidiotypic IgG, directed against IgG F(ab')2 anti-TT obtained from the cell donor, minimally inhibited the binding of TT-reactive T cells to TT pulsed M phi monolayers. M phi pulsed with urea-denatured TT, which contained less than 1% native TT, depleted T cell reactivity to TT to an extent almost equivalent to that achieved by M phi pulsed with native TT. These results indicate that human antigen-reactive T cells bind to the DR determinants of M phi pulsed with antigen and that the immunogenic moiety of antigen recognized by the majority of antigen reactive human T cells may differ from native antigen.

Adsorption↗
PubMed1982

Characteristics of the pulsed ultrasound field.

Pulsed ultrasound fields show some quantitative differences from continuous fields. In order to support the analysis of bioeffects of pulsed ultrasound fields these differences are characterized. For each observation point, the sound pulse is calculated by wavelet addition. The total pulse length has a maximum near the transducer surface, corresponding to large differences in acoustical pathlength from the surface elements. Accordingly, the spectrum varies strongly in the near field. In the far field, pulse-length and spectrum are almost constant as long as frequency-dependent absorption is negligible. The radiation field at each point is described by the time integral of sound intensity over one pulse (energy transport per unit area) and by the corresponding "dose" (absorbed energy per unit volume in one pulse). Differences between the spatial distributions of these two quantities are mainly detectable in the near field, which is also the region where differences between continuous and pulsed ultrasound (at the same centre frequency) are considerable.

Energy Transfer↗
PubMed1993

[Trials in ab-interno sclerostomy with a pulsed dye laser using a scleral dye: reactive black 5].

Several reports have described the successful performance of ab interno sclerostomies using a pulsed dye laser (666 nm) a goniolens and methylene blue as a scleral dye. However, the laser energy was found to have a bleaching effect on the methylene blue; therefore, methylene blue was replaced by reactive black-5 (RB-5), which seemed to be a more stable dye. To assess laser parameters using RB-5 we compared the number of pulses needed to perforate excised human sclera at different pulse durations (4-8 microseconds), energy levels (50, 100, 130-150, 200, 300 mJ) and delivery angles (20 degrees, 30 degrees, 45 degrees, 90 degrees). Fewer pulses were needed at a shorter pulse duration and higher energy levels. Above 200 mJ, 8 pulses for perforation could not be reduced; however, the width of the fistula increased. With a decrease in the delivery angle, the number of pulses for perforation increased non-proportionally above the calculated increase of the length of the fistula. At an angle of 20 degrees no perforation could be achieved even if 200 pulses of the maximal energy of 200 mJ were applied. This indicates that eyes with flat anterior chambers cannot be successfully treated.

Coloring Agents↗
PubMed1993

Precise ablation of skin with reduced collateral damage using the femtosecond-pulsed, terawatt titanium-sapphire laser.

BACKGROUND AND DESIGN: The precise ablation of skin was studied using an ultrashort-pulsed, high-intensity titanium-sapphire (Ti:Al2O3) laser capable of peak intensities of tens of terawatts (TW; 1 TW = 10(12) watts [W]) per square centimeter. Rat skin was exposed in vitro to femtosecond-pulsed Ti:Al2O3 laser radiation at 800 nm, while varying the number of pulses and the intensity up to 46 TW/cm2. Ablation was evaluated by monitoring the amount of tissue removed per pulse as a function of energy, and by light microscopic examination of damage to adjacent, nonirradiated tissue. OBSERVATIONS: Ablation depth per pulse was 0.1 micron at threshold intensity, and it was increased with both the energy per pulse and the number of pulses. Minimal damage to adjacent healthy tissue was observed, varying 0 to 30 microns. CONCLUSION: The results suggest that ablation of skin with femtosecond-pulsed, terawatt Ti:Al2O3 laser may have potential for precision cutaneous surgery, and in vivo studies are indicated.

Animals↗
PubMedDate not supplied

The effect of a perioperative steroid pulse on surgical stress in hepatic resection.

Little has been reported on the control of cytokine release, which is induced by surgical stress. The aim of this study was to investigate the effect of a perioperative short-term steroid pulse on surgical stress. Seventeen patients with a non-cholestatic liver, who underwent hepatic resection, were included in this study. The patients were classified into two groups consisting of a control group (n = 11) and a steroid pulse group (n = 6), in whom 30 mg/kg of methylprednisolone was intravenously administered 3 hours before the operation, and thereafter 1 gram of methylprednisolone was also intravenously administered both immediately after operation and on postoperative day 1. Interleukin 6 was serially measured, and the perioperative clinical parameters including C-reactive protein were compared between both the control and the steroid pulse groups. The IL-6 values immediately after operation, as well as at postoperative days 1 and 3 in the steroid pulse group were significantly lower than those in the control group. The value of the C-reactive protein at postoperative day 3 in the steroid pulse group was significantly lower than that in the control group, and the postoperative peak value of bilirubin as well as the incidence of postoperative complications in the control group tended to be higher than those in the steroid pulse group. In addition, the steroid pulse demonstrated no adverse side effects. A perioperative short-term steroid pulse using methylprednisolone is thus suggested to reduce surgical stress by decreasing cytokine release.

Aged↗
PubMed1996

Time discrete, near infrared photoplethysmography (NIRP) for non-invasive investigation of the volume pulse in man.

UNLABELLED: In pulse oximetry the principles of photoplethysmography are used for determination of heart rate and in some devices to also display the volume pulse. It has been suggested, that a more detailed analysis of the signal may allow quantitative analysis of peripheral hemodynamic events. We describe a new computer assisted time discrete analysis of the volume pulse, studying its reliability and the method s fundamental assumption of a linear relationship between changes in amplitude and changes in time sequences of the volume pulse. METHOD: In a finger clip two diodes emit near infrared (840 nm, NIR) and red light (640nm, RED) into the finger tip, where it is remitted mainly by the erythrocytes. 70 sec of recorded signal is filtered and the resulting volume pulse analysed off-line using a computer. On each volume pulse the time of the first (Tmax), the second maximum (time of dicrote, Td) and the duration of the volume pulse (Tp) are measured and the mean values displayed. In addition, the fundamental arterial oscillation Tag = Td - Tmax and all the above values in relation to Tp are calculated. Using NIRP, 54 healthy young volunteers (19 female, mean age 27.0 +/- 3.4 years) were studied and the individual mean values calculated from 960 measurements. The reliability during 10 repetitive measurements was investigated in 26 of the 54 volunteers. In 12 subjects 5 repetitive measurements were obtained from each finger and compared with each other. In 11 subjects the linear relationship between amplitude and time sequence was tested on > 30 000 single volume pulses. The finger clip photoelectrode was levelled with the right atrium in all measurements, skin close to the clip and room temperature were recorded. RESULTS: From the mean individual values the following time discrete values were calculated for the NIR signal (n = 41): Tp = 882.3 +/- 142.6 ms, Tmax = 214.8 +/- 28.3 ms, Td = 452.7 +/- 32.4 ms, Tdec = 667.4 +/- 133.6 ms, Tag = 237.9 +/- 36.3 ms, Tmax/Tdec = 0.34 +/- 0. 07, Td/Tdec = 0.7 +/- 0.11. For each parameter the individual standard deviation during 10 repetitive measurements (26 subjects) ranged between 2.2 and 6.1%. The time sequences found were not significantly different between the individual fingers. A linear relationship between changes in time sequence and changes in amplitude was found in all tested subjects (mean r = 0.96). CONCLUSION: These results show, that the values obtained with time discrete NIRP are highly reproducible and show an individual SD of less than 6.5% under steady state conditions. The linear relationship between time sequence and amplitude found in the present study has to be confirmed in further studies on patients with pathologies of the macro- and microcirculation.

Adult↗
PubMedDate not supplied

Determination of the optimal pulses in MR imaging with magnetization transfer contrast at 7 Tesla.

OBJECTIVE: The magnetization transfer contrast (MTC) effect depends on the shape, duration, amplitude, and offset frequency of the saturation pulse. In the present study, we investigated optimal combinations of these four parameters in vitro. METHODS: All experiments were performed with a 7.05 Tesla MR system, and the spin echo technique (TR 500/TE 30) was adopted. We used a simple phantom composed of 1% agar and water, representing restricted and free proton pools, respectively. Signal intensity changes were measured in the agar (Ma) and water (Mw), when the shape, duration, magnitude, and offset frequency of the saturation pulses were varied. The MTC effect was examined with the Mw/Ma ratio. RESULTS: The suppression of Mw was less with the gauss pulse than with the square and sinc pulses. The gauss pulse had the best MTC effect. The suppression of both Ma and Mw was greatest with a saturating duration of 60 msec. The MTC effect was greatest with a longer saturation pulse. The larger the amplitude, the stronger the MTC effect obtained. Mw was suppressed with an offset frequency of less than 3 kHz, and the MTC effect was greatest with an offset frequency closer to the spectrum of the free proton pool. CONCLUSION: In the present study the optimal MTC pulse at 7 Tesla is the gauss pulse with longer duration, maximal amplitude, and approximately 3 kHz off resonance.

Contrast Media↗
PubMed2000

Pulse pressure not mean pressure determines cardiovascular risk in older hypertensive patients.

BACKGROUND: Current guidelines for the management of hypertension rest almost completely on the measurement of systolic and diastolic blood pressure. However, the arterial blood pressure wave is more correctly described as consisting of a pulsatile (pulse pressure) and a steady (mean pressure) component. OBJECTIVE: To explore the independent roles of pulse pressure and mean pressure as determinants of cardiovascular prognosis in older hypertensive patients. METHODS: This meta-analysis, based on individual patient data, pooled the results of the European Working Party on High Blood Pressure in the Elderly trial (n = 840), the Systolic Hypertension in Europe Trial (n = 4695), and the Systolic Hypertension in China Trial (n = 2394). The relative hazard rates associated with pulse pressure and mean pressure were calculated using Cox regression analysis, with stratification for the 3 trials and with adjustments for sex, age, previous cardiovascular complications, smoking, and treatment group. RESULTS: A 10-mm Hg wider pulse pressure increased the risk of major cardiovascular complications; after controlling for mean pressure and the other covariates, the increase in risk ranged from approximately 13% for all coronary end points (P = .02) to nearly 20% for cardiovascular mortality (P = .001). In a similar analysis, mean pressure predicted the incidence of cardiovascular complications but only after removal of pulse pressure as an explanatory variable from the model. Furthermore, the probability of a major cardiovascular end point increased with higher systolic blood pressure; at any given level of systolic blood pressure, it also increased with lower diastolic blood pressure, suggesting that the wider pulse pressure was driving the risk of major complications. CONCLUSIONS: In older hypertensive patients, pulse pressure not mean pressure is the major determinant of cardiovascular risk. The implications of these findings for the management of hypertensive patients should be further investigated in randomized controlled outcome trials in which the pulsatile component of blood pressure is differently affected by antihypertensive drug treatment.

Aged↗
PubMed2002

Potential for use of pulse wave analysis in determining the interaction between sildenafil and glyceryl trinitrate.

BACKGROUND: The early part of the central aortic pressure pulse, with amplitude (PI - Pd), is generated by left ventricular ejection, while the latter part (or augmented pressure), with amplitude (Ps - Pi), is generated by the reflected wave arriving during systole. The effects of arterial vasodilator agents, especially nitrates, on central aortic systolic blood pressure are grossly underestimated by sphygmomanometric measurements of brachial artery pressure. HYPOTHESIS: The objective of this study was to investigate the potential for use of central arterial pulse wave analysis, obtained noninvasively from the radial pulse, in determining the interaction between sildenafil and the nitric oxide donor drug glyceryl trinitrate (GTN). METHODS: Central aortic pressure waveforms were generated from noninvasively measured radial artery pressure wave-forms and subjected to pulse wave analysis to determine the interaction between sildenafil and transdermally applied GTN. RESULTS: Transdermal GTN (2.5, 5.0, and 15 mg per 24-h patches) alone caused no consistent change in sphygmomanometer-determined systolic or diastolic pressures, but there was a consistent, dose-related fall in amplitude of the augmented systolic pressure, (Ps - Pi), of 4.0, 7.0, and 11 mmHg, respectively, with little change in diastolic pressure. The 2.5 mg patch caused a fall of 4.0 mmHg in aortic systolic pressure, while augmentation index (AIx) fell from 20 to 11% and pulse pressure fell 18%. When oral sildenafil (50 mg) was administered after GTN (2.5 mg), aortic systolic pressure fell another 4.0 mmHg. This decrease in systolic pressure caused a fall in AIx to almost 0.0%; pulse pressure fell another 9.0%. CONCLUSION: These modifications in aortic systolic and pulse pressure are due primarily to reduction in wave-reflection amplitude and are not detected by sphygmomanometer-measured brachial artery pressure.

Administration, Cutaneous↗
PubMed1995

Effect of spike pulses on the orientation of the agarose gel matrix.

The orientation of the agarose gel matrix in two-part, "stair-step" electric fields has been studied by transient electric birefringence. Stair-step electric fields are those in which a pulse of a given amplitude is immediately followed by a short, higher voltage "spike" pulse of the same polarity. A single stair-step pulse orients the agarose gel matrix as though the two portions of the pulse were individually applied to the gel. However, a series of consecutive stair-step pulses causes an anomalous increase in the amplitude of the birefringence, suggesting that increased numbers of agarose fiber bundles are orienting in the electric field. Spike pulses > or = 10 V/cm appear to cause junction zone breakdown, freeing large numbers of agarose fiber bundles and microgel domains from the constraints of the gel matrix. The implications of these results for pulsed field gel electrophoresis are discussed.

Birefringence↗
PubMed1989

The application of spinors to pulse synthesis and analysis.

We show how spinors may be used to solve many problems in pulse synthesis and analysis. They provide an elegant simple notation for many problems. We show how one can specify the component of a spinor and then, by exactly solving the Bloch equations, synthesize a hard pulse sequence or a soft pulse which will yield the desired spinor. This is done by generalizing our previous approach to inverting the Bloch equations. This can be applied to synthesizing refocusing pulses. Finally, some simple consequences about symmetric pulses are derived. It is shown that given a symmetric inversion pulse, one can always synthesize an asymmetric inverting pulse of the same duration, which, as an inversion, is better.

Humans↗
PubMed1975

The genesis of the pulse contours of the distal leg arteries in man.

In order to clarify the genesis of the human pressure and flow pulse contours of the distal leg arteries, in particular the posterior tibial artery, pulse recordings were performed with transcutaneous techniques under normal conditions and in the state of strong vasodilatation (reactive hyperaemia) in the distal parts of the lower legs. From the experimental results it is concluded that the contour of the incident pressure wave arriving in the leg arteries is very similar to the pressure pulse contour of the abdominal aorta, while the resulting contour in the leg arteries is determined by this incident wave and superimposed reflected waves. The latter arise from positive reflection in the periphery of the lower legs. The travel in retrograde direction, are reflected negatively in proximal regions, particularly in the abdominal aorta, and appear again, with opposite sign, in the leg arteries. In addition, retrograde waves reflected positively at the aortic valve and then traveling in antegrade direction also influence the pulse contours. By considering this wave travel, the genesis of the characteristic contours of the pressure and flow pulses of the lower leg arteries is explained in a satisfactory way. This is demonstrated by a simplified graphical pulse construction as well as by the calculation of pulse contours on the basis of a theoretical tube model of the arterial system with the aid of a digital computer. The results of these calculations are discussed with respect to the findings of previous investigators who used analog and digital models of the arterial system.

Adolescent↗
PubMedDate not supplied

[The pulse-respiratory quotient of persons with stable and instable postural circulation while standing (author's transl)].

The pulse-respiratory quotient of patients with postural circulatory instability is the same in a prone position as that of patients with stable postural circulation, however, it is higher in an upright postiion. This is not only caused by the higher pulse frequency of postural circulatory instable patients while standing, but also by the lower respiratory rate. The difference of the pulse-respiratory quotient between standing and lying indicates with more accuracy the diagnosis of postural circulatory instability. The severity of the symptoms is related not only to the pulse and respiratory rate, but also to the pulse-respiratory quotient. Tachycardiac patients with a high pulse-respiratory quotient show clinically symptoms more severe than tachycardiac patients with lower pulse-respiratory quotients. Due to the results shown here, the terms of rhythmical concordance and discordance are proposed.

Adolescent↗
PubMedDate not supplied

[Principles of the genesis of pressure and flow pulse contours of the human carotid artery (author's transl)].

In order to clarify the genesis of the characteristic pressure and flow pulse contours of the common carotid artery of man, at first transcutaneous pulse recordings were carried out on healthy resting subjects during breathing of room air and of a mixture of 95% O2 and 5% CO2 (Carbogen). The latter was used to cause vasodilation of the cerebral resistance vessels and thus reducing the peripheral reflection coefficient. Secondly pulse constructions were performed by means of a theoretical inhomogeneous tube model using a digital computer. A side branch of this model represented the carotid artery. The pressure pulse of the aortic arch of the model was used as generating pulse for the carotid system. A satisfactory simulation of the carotid pressure and flow pulse contours under normal conditions and during peripheral vasodilation requires an intermediate reflection (positive for antegrade waves) at a site near the middle of the total transmission time of the carotid model system. The adequacy of the model is demonstrated by comparison of the recorded and constructed pulses.

Adult↗
PubMed1996

Continuous pulse amplitude monitoring of infrainguinal bypass grafts in the first 24 postoperative hours.

To evaluate continuous pulse amplitude monitoring (CPAM) as a method for early postoperative graft surveillance following infrainguinal bypass surgery, a prospective observational study was carried out in 34 consecutive infrainguinal bypass grafts. CPAM tracings were compared with pre- and postoperative pulse palpation, ankle/brachial index (ABI) measurements, and pulse volume recordings (PVR). The utility of each method was defined by its ability to demonstrate graft patency in the first 24 hours. Pulse palpation was considered a useful monitoring tool if a postoperative pedal pulse was found in the absence of palpable preoperative pulses. The ABI qualified in this respect if a postoperative increase of at least 0.25 could be demonstrated; for PVR tracings an increase of at least one category was required. The utility of CPAM was established by an increase of at least 5 mm compared to the preoperative values. There were no early graft failures. We were therefore unable to calculate the ability of the studies to predict graft failure. The percentages (95% confidence limits) for which pulse palpation, ABI, and PVR were found capable of demonstrating graft patency were 50% (range 34% to 66%), 53% (range 36% to 70%), and 71% (range 54% to 83%), respectively. CPAM appeared to be far superior to these three methods with a utility of 94% (range 81% to 98%; p < 0.05). Patient and operator acceptability of CPAM was high. Skin pressure problems are a potential risk if the CPAM probe is left attached to the skin for more than 24 hours. CPAM was a valuable and reliable means of monitoring infrainguinal vascular reconstructions. Apart from being inexpensive, continuous, objective, and simple, CPAM is noninvasive and painless. It is advisable to remove the probe 24 hours after surgery, when the most crucial period for graft monitoring has passed.

Adult↗
PubMed2006

Absent pedal pulse and impaired balance in older people: a cross-sectional and longitudinal study.

BACKGROUND AND AIMS: The purpose of this study was to determine the relationship between abnormal pedal pulse status and postural balance in older people. METHODS: Prospective, population-based cohort study of older residents in the city of Jyväskylä, Finland. A total of 419 individuals aged 75 or 80 at baseline, with known lower extremity pulse status and balance tests performed on a force platform, were eligible for analysis. RESULTS: Cross-sectionally, persons with both dorsal pedal artery pulses absent were found to sway more (p=0.047 anteroposterior velocity, normal standing eyes-open position). The risk of being unable to do the full tandem stance was twofold (OR=2.20, 95% CI 1.29-3.78) for persons without palpable dorsal pedal arteries compared with those with normal pulse status. Balance deterioration was observed at five years (p<0.001 for time) but without group-by-time interaction. At ten years, however, the interaction term became significant for the normal standing eyes-closed position (p=0.025 for anteroposterior velocity and p=0.026 for mediolateral velocity), indicating greater balance deterioration among those with both dorsal pedal artery pulses absent. CONCLUSIONS: According to our study, the absence of both dorsal pedal artery pulses is associated with impaired balance in older people. The association was observed both cross-sectionally and longitudinally. In addition, as diminished pedal pulses are frequently associated with impaired lower extremity circulation, our results have also produced information on the possible pathophysiological mechanisms of balance deterioration in older people, which warrant further study.

Aged↗
PubMed1999

Intravenous cyclophosphamide pulse therapy for the treatment of lung disease associated with scleroderma.

Until recently, renal crisis was the most significant cause of morbidity and mortality in patients with scleroderma (SSc). Nowadays, following the introduction of angiotensin-converting enzyme inhibitors used in renovascular hypertension, pulmonary fibrosis and pulmonary hypertension have become the most common causes of death in SSc. Consequently, the early diagnosis and treatment of pulmonary fibrosis is essential to improve morbidity and mortality in SSc patients. The aim of this study was to investigate the effect of intravenous cyclophosphamide pulse therapy in patients with SSc and evidence of active alveolitis assessed on a high resolution computed tomographic (HRCT) scan, and to compare the effect of cyclophosphamide pulse therapy with oral therapy. Sixteen consecutive patients with SSc were allocated alternately to the two treatment groups. Eight patients were treated with monthly cyclophosphamide pulse therapy (750 mg/ m2) for 12 months; the other eight patients were treated with oral cyclophosphamide (2-2.5 mg/kg/day) for the same period. All patients received concurrently prednisone (10 mg/day). Pulmonary function tests and HRCT scans were performed before therapy and at 6 and 12 months. In the oral cyclophosphamide group, three patients with a grade I pattern showed regression of disease extent. In the other five patients (one with grade II and four with grade III) the pattern and extent of disease remained stable during the study. No statistical differences were found in forced expiratory volume in 1 s, forced vital capacity and total lung capacity during the study period. The diffusing capacity for carbon monoxide increased significantly between baseline and 12 months (p = 0.043). In the cyclophosphamide pulse therapy group, seven patients with a grade I pattern showed regression of disease extent at 6 months (p = 0.018) and 12 months (p = 0.012). One patient with grade III remained stable during the study. In both groups the regression of the extent of disease estimated on HRCT was due to a decrease in the ground glass appearance. The extent of the reticular appearance remained stable throughout the study. Our results indicate that cyclophosphamide pulse therapy is effective in suppressing active alveolitis (ground glass appearance). Although in this study it is not possible to compare pulse therapy with oral therapy because of the different pattern seen on HRCT between the two groups, it seems that oral therapy is also effective in suppressing active alveolitis. Neither regimen improved pulmonary involvement when the reticular appearance predominated over the ground glass appearance on HRCT. It is concluded that either pulse or oral cyclophosphamide therapy may improve the outcome of SSc patients.

Adult↗
PubMed1979

R--pulse wave timing: a technique for continuous cardiovascular monitoring in obstetrics--preliminary report.

A simple, noninvasive technique for continuous cardiovascular monitoring in obstetrics using R--pulse wave timing is described. This preliminary study suggests that different maternal heart rate/R pulse patterns are found in different clinical circumstances. A significant decrease in the R pulse interval occurred in the third trimester in both normal and diabetic women in the left lateral position when compared to the supine position. The R pulse intervals were all prolonged in the standing position in both gravid and nongravid women. During labor R pulse interval usually shortened during uterine contraction. Prolongation of R pulse interval was observed during thiopental injection, hypotension, and excessive bleeding at cesarean section. Exercise testing in healthy male subjects suggested that the change in R pulse interval becomes constant when the oxygen consumption rate reaches a plateau at 100% maximal work load. Further extensive clinical study appears worthwhile since it may add another dimension to cardiovascular monitoring and give an early indication of cardiovascular reserve.

Anesthesia, Obstetrical↗