Further evidence of a prolonged hypotensive and a bradycardic effect after mandibular extension in normal volunteers.

We previously reported that in normotensive humans submaximal mouth opening (mandibular extension) obtained by an ad hoc dilator (spring device), associated with partial masticatory movements and prolonged for 10 minutes is followed by a long-lasting reduction of blood pressure (BP) and heart rate (HR). Similar results were obtained by us in anesthetized rats. A recent independent study failed to confirm the results in the normotensive human. We reassessed, in 25 normotensive volunteers, the effects on BP and HR of mandibular extension obtained by the spring device associated with partial masticatory movements compared to a control procedure, consisting in keeping a tongue depressor between the incisor teeth. Both procedures were applied for 10 minutes and systolic BP (SBP), diastolic BP (DBP) and HR were measured every 10 minutes by an automatic recorder, for 30 minutes before and 120 minutes after the procedures in seated subjects watching nature documentary films on laptop screen.Baseline levels (mean of the last 3 measurements before procedure) did not significantly differ between the experimental and control sessions. Two way repeated measures ANOVA on absolute (recorded) values did not reveal a significant main effect of treatment for SBP, DBP and HR, but a significant main effect of time (P<0.001) for BP and HR. In addition, a significant interaction of time and treatment was found for SBP (P<0.001) and DBP (P=0.005), but not for HR. In addition, two way repeated measures ANOVA was done on changes from baseline obtaining a significant main effect of treatment (P<0.001) and time (P<0.001) and a significant interaction of time and treatment for SBP (P<0.001) and DBP (P<0.01). Post-hoc comparisons revealed significantly lower values for SBP and DBP in experimental compared to control values at almost all times and this decrement was by about 5 mmHg. Furthermore, for both absolute values and changes from baseline, the interaction effect was, for BP, of a qualitative type as indicated by an opposite effect in the time-course between control and experimental sessions. This study thus provides confirmatory evidence that submaximal mouth opening for a relatively brief time is followed by prolonged albeit small reductions of BP in normotensive human volunteers.

Persistent effects after trigeminal nerve proprioceptive stimulation by mandibular extension on rat blood pressure, heart rate and pial microcirculation.

The trigemino-cardiac reflex is a brainstem reflex known to lead to a decrement in heart rate and blood pressure, whereas few data have been collected about its effects on the cerebral hemodynamic. In this study we assess the in vivo effects of trigeminal nerve peripheral stimulation by mandibular extension on pial microcirculation and systemic arterial blood pressure in rats. Experiments were performed in male Wistar rats subjected to mandibular extension obtained inserting an ad hoc developed retractor between the dental arches. Mean arterial blood pressure and heart rate were recorded and the pial arterioles were visualized by fluorescence microscopy to measure the vessel diameters before (15 minutes) during (5-15 minutes) and after (80 minutes) mandibular extension. While in control rats (sham-operated rats) and in rats subjected to the dissection of the trigeminal peripheral branches mean arterial blood pressure, heart rate and pial microcirculation did not change during the whole observation period (110 minutes), in rats submitted to mandibular extension, mean arterial blood pressure, heart rate and arteriolar diameter significantly decreased during stimulation. Afterward mean arterial blood pressure remained reduced as well as heart rate, while arteriolar diameter significantly increased evidencing a vasodilatation persisting for the whole remaining observation time. Therefore, trigeminal nerve proprioceptive stimulation appears to trigger specific mechanisms regulating systemic arterial blood pressure and pial microcirculation.

The ovarian cycle as a factor of variability in the laboratory screening for primary aldosteronism in women.

Primary aldosteronism is increasingly investigated in hypertension being associated with an elevated cardiovascular risk. Aldosterone has been reported to increase in the luteal phase in normal women but to our knowledge the influence of the ovarian cycle on the first screening for primary aldosteronism (that is, on the levels of plasma aldosterone and its relationship to PRA levels) was never investigated. We measured hormonal levels during one cycle in 26 low-renin mild hypertensive outpatients. LH, FSH, 17 beta-estradiol, progesterone, aldosterone and PRA were assayed at the seventh, fourteenth, twenty-first and twenty-eighth days of the cycle after 30 min of recumbency. Aldosterone and PRA increased from the seventh (follicular phase) to twenty-first day (luteal phase) from 11.2 to 17.8 ng 100 ml(-1) and from 0.23 to 0.35 ng ml(-1) h(-1), respectively (both P=0.004) The proportion of patients with aldosterone >15 ng 100 ml(-1) significantly increased from the follicular to the luteal phase, (8/26 vs 19/25, P=0.018); a similar increase was found for Aldosterone-PRA Ratio >30 combined with either a minimum PRA value of 0.5 ng ml(-1) h(-1) or aldosterone >15 ng 100 ml(-1) (7/26 vs 16/25 and 7/26 vs 17/25 respectively, P<0.05). Aldosterone was positively related to PRA and progesterone. Higher aldosterone levels may be frequently encountered in the second part of the ovarian cycle in low-renin hypertensive women. This variability appears to be an important factor to be taken into account in the first-step laboratory screening for primary aldosteronism and should be considered in the process of standardization of the diagnostic work-up for this disease.

Effect of canrenone on the digitalis site of Na+/K(+)-ATPase in human placental membranes and in erythrocytes.

It has been reported that canrenone, which is used in hypertensive therapy as an antialdosteronic drug, may also act as a blocker of ouabain effects. Several studies suggest that human plasma contains an endogenous ouabain-like factor similar to ouabain, which may be increased in hypertension, in pregnancy, and in the neonatal state. This study evaluated (1) the effect of canrenone on Na+/K(+)-ATPase in relation to ouabain in human placental membranes and erythrocytes by 3H-ouabain binding assay; (2) the capacity of canrenone (10 microM) to reverse the inhibition of Na+/K(+)-ATPase by ouabain and by ouabain-like factor (from umbilical cord plasma) in human erythrocytes employing a 86Rb uptake assay. Increasing concentrations of canrenone (0-350 microM) partially competed with 3H-ouabain binding in placental membrane (40%) and erythrocytes (60%). Scatchard plot from radioreceptor assay in placental membrane showed that ouabain and canrenone compete for the same binding site. In erythrocytes, canrenone completely reversed the inhibition caused by ouabain (5 x 10(-9) M) and ouabain-like factor (2 x 10(-9) M ouabain equivalents). A reduction of inhibition of about 50% was observed with ouabain and ouabain-like factor respectively at a concentration of 5 x 10(-8) M and 2 x 10(-8) M (ouabain equivalents). Our results thus provide evidence that canrenone, at therapeutical concentrations, is a partial competitive agonist of ouabain and of ouabain-like factor in human placental membranes and erythrocytes.

Are serum inhibin concentrations new markers of placental tumours in the course of chemotherapy?

BACKGROUND: The study was conducted to evaluate whether the detection of serum molecular forms of inhibin (A and B) could be useful for the diagnosis, prognosis and follow-up of placental tumours. METHODS: A total of 17 patients with hydatidiform mole (n = 13), invasive mole (n = 1) or choriocarcinoma (n = 3) were studied; serum concentrations of inhibins A and B, human chorionic gonadotrophin (HCG) and its free beta subunit (HCGbeta) were measured before chemotherapy (after mole evacuation for eight patients) and also during the course of chemotherapy (for 10 patients). RESULTS: After evacuation or before chemotherapy for refractory disease, serum inhibin A and B concentrations were found to be increased in 10/17 and 4/17 patients, when HCG and HCGbeta were high in all patients. In 10 patients with a follow-up during treatment, nine had a high concentration of inhibin A which correlated with those of HCG and HCGbeta. Normalization of inhibin A was faster than that of HCG and HCGbeta for three and six patients respectively. There was no correlation between changes of inhibin B and HCGbeta concentrations. CONCLUSIONS: Our results suggest that inhibins A and B are not useful markers and that HCG determination still remains the most useful marker for diagnosis and follow-up of placental tumours.

Increased circulating levels of ouabain-like factor in patients with asymptomatic left ventricular dysfunction.

BACKGROUND: Much evidence has been accumulated that human plasma contains digitalis-like factor(s) with Na/K ATPase inhibitor properties. Increased concentrations of ouabain-like factor (OLF) have been reported in patients with moderate to severe hypertension and in patients with overt congestive heart failure due to dilated cardiomyopathy. AIM: The presence of circulating OLF has not been investigated in borderline to mild hypertension or in the early stage of dilated cardiomyopathy. METHODS AND RESULTS: The study population consisted of 18 normal volunteers, 24 patients with borderline to mild hypertension, 47 patients with asymptomatic left ventricular dysfunction (ALVD) due to dilated cardiomyopathy and 26 patients with cardiac arrhythmias but normal left ventricular function. OLF values (pM ouabain equivalent) were assayed in extracted plasma, using a radioimmunoassay for ouabain. OLF was, respectively, 29.4+/-20.6 pM in normal controls, 39.1+/-23.8 pM in hypertensives, 35+/-18 pM in patients with cardiac arrhythmias, 52.3+/-25.8 pM in ALVD patients not treated with digoxin and 64.6+/-29.6 pM in ALVD patients treated with digoxin. Patients with ALVD, both treated and not treated with digoxin, had OLF significantly higher (P<0.05) than all the other groups. In patients with ALVD no correlation between OLF and left ventricular ejection fraction was observed. In the hypertensive group no correlation between OLF and both diastolic and systolic pressure was found. CONCLUSION: Increased concentrations of OLF were observed in patients with left ventricular dysfunction due to dilated cardiomyopathy, before the occurrence of overt heart failure, suggesting that OLF may be an early marker of the disease.

Selective inhibition of human erythrocyte Na+/K+ ATPase by cardiac glycosides and by a mammalian digitalis like factor.

Na+/K+ATPase is a transport membrane protein which contains the functional receptor for digitalis compounds. In this work we compare the inhibition curves of Na+/K+ATPase measured by the inhibition of 86Rb uptake in human red blood cells by cardiac glycosides and by an endogenous digitalis like factor (EDLF) extracted from human newborn cord blood. The curves of Na+/K+TPase inhibition show a monophasic shape for ouabain, strophantidin, digitoxin, proscillaridin and EDLF whereas a biphasic shape for ouabagenin, digoxin, digoxigenin and digitoxigenin. All the drugs are potent inhibitors of erythrocyte Na+/K+ATPase with an IC50 ranging from 1.8 x 10(-9) M to 1.4 x 10(-11) M for the higher affinity binding site and from 1.8 x 10(-6) M to 5.5 x 10(-9) M for the lower affinity site. Digitoxigenin is the most active showing the higher active site at 1.4 x 10(-11) M. Ouabain and digoxin have higher affinity compared with their corresponding genins, while digitoxigenin shows a binding site with higher affinity than the respective cardiac glycosides. The increased affinity of the drugs to Na+/K+ATPase may be related to a lipophilic region in correspondence of the carbons 10, 9, 11, 12, 13 of the steroid nucleus, situated in the opposite side with respect of the C-OH-14. The comparison of the inhibition curves and the HPLC profile of newborn EDLF and of the investigated cardenolides suggest that EDLF may be a compound identical or very similar to ouabain.

Endogenous digitalislike factors in obstructive sleep apnea.

Recent studies have provided evidence that hypoxia may stimulate the release of endogenous digitalislike factors (EDLF). Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia during sleep and may be associated with sympathetic activation and a high risk of developing hypertension. This study was designed to measure EDLF in the plasma of patients with OSA diagnosed by polysomnography, with patients being classified by the number of apneic-hypopneic episodes/h sleep (apnea-hypopnea index, AHI). Plasma was obtained in the morning from 8 male normotensive OSA patients (OSA-N) (AHI 70+/-6), 2 untreated hypertensive OSA patients (OSA-HT), and 11 age-matched healthy male controls (C). EDLFs of different hydrophobicities were separated from the same plasma sample by solid-state C18-cartridges with 25% acetonitrile (ACN) (EDLF-1) followed by 40% ACN (EDLF-2). This procedure recovered ouabain in the first fraction and digoxin and digoxigenin in the second. EDLF was quantified in pM ouabain-equivalents by a human placenta radioreceptor assay. EDLF-1 levels were similar for OSA-N and C (231+/-55 vs. 258+/-58), whereas EDLF-2 levels were increased in OSA-N (244+/-51 vs. 110+/-25 in C, p=0.02). Norepinephrine was increased in apneics. The two OSA-HT had EDLF and norepinephrine levels similar to OSA-N. These preliminary results suggest that OSA is associated with an increase in the more hydrophobic EDLF levels in both normotensive and hypertensive states. No significant increase was found for the less hydrophobic ouabain-like EDLF.

Exposure to a hypogeomagnetic field or to oscillating magnetic fields similarly reduce stress-induced analgesia in C57 male mice.

Previous studies have shown that exposure to altered magnetic fields alters analgesic responses in a variety of species, including humans. Here we examined whether deprivation of the normally occurring geomagnetic field also affects stress-induced analgesia, by measuring the nociceptive responses of C57 male mice that were restraint-stressed in a hypogeomagnetic environment (inside a mu-metal box). Stress-induced analgesia was significantly suppressed in a manner comparable to that observed in mice that were either exposed to altered oscillating magnetic fields or treated with the prototypic opiate antagonist naloxone. These results represent the first piece of evidence that a period in a hypogeomagnetic environment inhibits stress-induced analgesia.

[Mesogastrectomy in the surgical treatment of gastric carcinoma. Experience with 61 cases]. / La mesogastrectomia nella chirurgia del carcinoma gastrico. Esperienza di 61 casi.

BACKGROUND: In gastric cancer surgery, to search for a technique to remove the entire posterior mesogastric region using a standardised operation using well defined methods and anatomic-embryological planes. METHODS: A concise description of the embryological evolution of the posterior mesogastrium allow the formation of the mesogastric fascia (and the supramesocolic fascia of the omentum--which is a continuation) to be documented. It is also clear that the mesogastric fascia is the embryological--anatomical equivalent of Treitz's fascia, pancreatic retro-head, and Toldt's retrocolic fascia, of which it is a structural continuation. Like Treitz's and Toldt's fascias, the mesogastric fascia also represents the surgical plane for the detachment of the region in question and allows maximum safety and radicality. By carrying out primary ligature of the arteries at the origin and the veins at the outlet, the entire posterior mesogastric region, with the relative lymph node stations, can be removed en bloc with maximum radicality and safety, and also in line with the principle of "no touch isolation". We used this technique to operate 61 cases, 17% of all cases of gastric carcinomas between 1973 and 1994. RESULTS: Mesogastrectomy was required in 87% of cases with carcinoma in a high localisation or widespread nature of the linitis plastica type. Only 23 cases (37%) were at pTNM II and III A stages. Thirty-eight cases (63%) were at stages III B and IV. In non-selected cases and those with severe associated pathologies and undergoing emergency surgery, and those cases that were extended beyond mesogastrectomy, morbidity was above all linked to pleural effusion. There were only 2 cases (3%) of operating mortality owing to two technical errors: an esophago-jejunal anastomotic dehiscence (the only case in the series, 1.6%) caused by esophageal cancer nests in the suture and a case of necrosis in the left hepatic region following the section of the left gastric artery at the origin despite the existence of a large hepatic collateral vessel. The results for stages II and III A were excellent: stage II, 100% survival at 5, 10 and 15 years; stage III A 88% survival at 5 years, 70% at 10 years, 55% at 15 years, but only two deaths from neoplasia at 2.7 and 4.6 years. The results for stages III B and IV are comparable to large series undergoing traditional forms of surgery. Postoperative conditions of nutrition and quality of life were good and patients resumed activities with the aid of constant chlorhydric-peptic replacement treatment and the total extraction of gastric mucosa. CONCLUSIONS: We believe that mesogastrectomy represents a real advance in both technical terms and results for stages II and III A; it is debatable for stages III B and IV, although individual cases who survived for more than 10 years were also reported. The case of a stage pT3N0M1 = IV pathology, with a single hepatic metastasis that increased until one year and then spontaneously resolved leaving the patient alive and in good health 20 years and 6 months after the operation is truly amazing.

[The single-stage surgery of colorectal neoplastic occlusion. The experience of 133 cases]. / La chirurgia in un tempo dell'occlusione neoplastica colon-rettale. Esperienza di 133 case.

BACKGROUND AND AIM: 133 cases of occluded colorectal neoplasms (14% of the entire series): 30 (23%) of the right colon, 103 (77%) of the left colon-rectum; 69 males (52%) and 64 females (48%); mean age 67.5 years old, range 33-91 years. pTNM: stage II, 28 cases (21%); stage III: 43 cases (32%); stage IV, 62 cases (47%). The aim of this study was to resolve the occlusive symptoms and to treat the neoplasm in a single operation. METHODS: In the 62 cases at stage IV, surgery was solely palliative: 49 (79%) derivations, 13 (21%) entero-enterostomies and 36 (58%) preternatural anus; 11 (18%) standard hemicolectomies, extended in two cases to hepatic resection, and 2 (3%) Hartmann's operations. In the 71 cases at stages II and III, surgery took the form of standard colic exeresis with primary ligature of the colonic vessels at source and at the outlet; 15 (21%) right colectomies, 50 (70%) left colectomies, extended in 6 cases (8%) to abdomino-perineal amputation; 6 segmentary colectomies, 3 (4%) of the transverse colon and 3 (4%) Hartmann's operations. The following aspects are essential in this single-stage surgery: urgency; massive dose antibiotic treatment limited to the pre- and perioperative stages; peritoneal cleansing using accurate, methodical, repeated and abundant lavage; perioperative colonic preparation using direct colotomic perioperative lavage or using a trans-buccoenteric access (using Grosz-Dennis tube); the peritonisation of the retroperitoneum with the omentum and the protection of the anastomosis using omental wrapping and active lavage and, for colorectal anastomosis, even using the 3-way tube, lavage and active aspiration, in a transanal trans- or sub-anastomotic position. Total parenteral feeding is useful for 6-7 days. RESULTS: In the 62 cases at stage IV, postoperative morbidity was 3 cases (6%): 3 suppurations of laparotomy, and mortality occurred in 10 cases (16%): one case of anastomotic disunion (pre-Gullino's tube), 3 cases of septic shock and 6 cardiorespiratory failures. Mean postoperative hospitalisation was 14 days. All these patients died owing to the spread of neoplasms within 1-40 months, mean 13 months. The worst results were obtained in entero-enterostomies: 1-9 months, mean 5 months. In the 71 cases at stages II and III, postoperative morbidity was 3 cases (4%): a small anastomotic filtration after right colectomy and 2 suppurations of the laparotomic incision; mortality amounted to 10 cases (14%): one case of septic shock, one of acute hepatitis, one intestinal infarction and one cardiac infarction, 3 pulmonary embolisms and 3 cardiorespiratory failures. Mean postoperative hospitalisation was 13 days, only 10 in cases of left colectomy with anastomosis protected by Gullino's tube. The long-term results were very good in these 71 patients: over 5-year survival of 50% (Kaplan-Meier). CONCLUSIONS: Using this courageous single-stage surgery, the results are optimal even at a distance, together with reduced surgical trauma and a shorter hospital stay.

Detection of digitalis compounds using a surface plasmon resonance-based biosensor.

An automated surface plasmon resonance-based biosensor system has been used to detect endogenous and exogenous digitalis-like factors (EDLF) in the pmolar range in real time. EDLF was purified from umbilical cord blood. EDLF has been suggested to play a role in hypertension and in perinatal adaptation. Highly specific polyclonal anti-ouabain antibodies showed a high affinity binding capacity for ouabain, ouabagenin and strophantidin with an IC50 value of 5 x 10(-10) M, 7.0 x 10(-10) M and 2 x 10(-8) M, respectively. EDLF cross-reacted with antibodies and its concentration in plasma at IC50 was around 50 pmol ouabain equivalent. This study shows the potential usefulness of the biosensor technology for biomolecular interaction analysis. The features of this technology (fully automated, measured in real time, sharpened response) offer several advantages compared with a traditional immunoassay like radioimmunoassay (RIA) in the detection of digitalis compounds in human fluids.

Do geomagnetic disturbances of solar origin affect arterial blood pressure?

OBJECTIVE: Episodic reports suggest that geomagnetic disturbances of solar origin are associated with biological and clinical events, including increased arterial blood pressure (BP). We reassessed this aspect by relating solar activity levels to ambulatory BP measured in our out-patient population. PATIENTS AND METHODS: The ambulatory BP measurements of 447 consecutive untreated patients attending a hypertension out-patient clinic who did a monitoring for diagnostic purposes over 5 years were retrieved. The mean daytime, night-time and 24-h BP and heart rate values were related to the temporally corresponding geomagnetic index k-sum obtained by the nearest observatory. K-sum is a local measurement of the irregular disturbances of the geomagnetic field caused by solar particle radiation. RESULTS: Significant to highly significant positive correlations were observed for k-sum with systolic (daytime and 24 h) and diastolic BP (daytime, night-time and 24 h), but not with heart rate. No correlations were found with the k-sum of 1 or 2 days before the monitorings. Multiple correlations which also included other potential confounding factors (date, age) confirmed a significant effect of k-sum on BP. Comparison made in season-matched subgroups of quiet and disturbed days (using three different criteria of definition), always showed significantly higher values in the disturbed days for all BP parameters except systolic night-time pressure. The difference between the quietest and the most disturbed days was of about 6 to 8 mm Hg for 24-h systolic and diastolic BP. CONCLUSION: These results are unlikely to be due to unrelated secular trends, but seem to reflect a real relation between magnetic field disturbances and BP.

Inhibition of rat Na+/K+-ATPase isoforms by endogenous digitalis extracts from neonatal human plasma.

An unique endogenous digitalis-like factor (EDLF) has been previously purified from human newborn cord plasma and its differential effects tested on the three well defined functional isoforms (alpha1, alpha2 and alpha3) of the alpha subunits of Na+/K+-ATPase in rat. EDLF specifically inhibits the enzymatic activity. It differs from ouabain by three criteria: a preincubation with the membranes is required for full activity, no effect on the rat cerebral alpha3 isoform and a steep dose-response curve with the same apparent potency for rat alpha2 and alpha1 isoforms of high (10(-7) M) and low affinity (3 x 10(-5) M) for ouabain. These results indicate that the Na+/K+-ATPase inhibitor involved in the regulation of sodium and body fluid volume and present in neonate and adult human plasmas is distinct from ouabain.

Ultrasonic myocardial texture in hypertensive mild-to-moderate left ventricular hypertrophy: a videodensitometric study.

Myocardial texture analysis of two-dimensional echocardiographic gray level distribution is abnormal in hypertensive patients with severe increase of left ventricular mass. The aim of this study was to investigate the behavior of this parameter in hypertensive patients with absent-to-moderate left ventricular hypertrophy, more representative of the overall hypertensive population. We compared male essential hypertensive patients, with absent or mild-to-moderate left ventricular hypertrophy, with normotensive sedentary healthy subjects as controls. The groups (n = 18 each) were age- (+/- 2 years) and sex-matched. All subjects performed ambulatory blood pressure measurements for the evaluation of 24 h mean systolic and diastolic blood pressure. Quantitative analysis of echocardiographic digitized imaging was performed through a calibrated 256 gray level digitization system to calculate midseptum and midposterior end-diastolic and end-systolic first and second order textural analysis. In particular were observed the mean gray level cyclic variations to deriving the cyclic variation index (CVI). The hypertensives showed a significantly lower CVI compared with controls both for septum (P < .001) and for posterior wall (P < .0001). No significant relationships were found between CVI and relative diastolic thickness both of septum and posterior wall. Conversely, a significant inverse relationship was found between systolic arterial pressure values and CVI both of septum and posterior wall. Abnormalities of two dimensional echocardiographic gray level distribution are present also in hypertensive patients with absent or with mild-to-moderate levels of left ventricular hypertrophy, but seem unrelated to the degree of echocardiographic hypertrophy as such. Changes in collagen network distribution or microcirculatory alterations, secondary to pressure-volume overload per se or to other complex humoral factors, could explain these abnormalities. Further work is needed to establish the clinical, therapeutic, and prognostic implications of these findings.

On the contribution of biomedical engineering and technology to the understanding and the management of arterial hypertension.

There are several reasons why arterial blood pressure, i.e. the pressure within the large arterial vessels, is out of the physical parameters of the human body, one of the most frequently measured. Firstly, arterial blood pressure is a physiologically meaningful parameter, since it represents the driving pressure generated by the heart which maintains blood perfusion in the periphery. Secondly, it is a clinically important parameter: a decline of arterial blood pressure (e.g. in shock) may represent a life-threatening emergency which requires prompt recognition and correction; elevated blood pressure (hypertension) on the other hand is a very common condition, which bears a high risk of cardiovascular mortality and morbidity and can be controlled with appropriate pharmacological means. Thirdly, but not lastly, arterial blood pressure is easily measurable with a fair degree of accuracy by the standard manual sphygmomanometric method and, more recently, by non-invasive automatic techniques. This paper discusses some of the aspects related to arterial blood pressure measurement, in which, in the author's opinion, medical engineering and technology are expected to provide useful advancements. Two major areas will be considered. The first regards the methodologies for arterial blood pressure assessment; the second the identification and acquisition of information additional to blood pressure which would be helpful for a better understanding of blood pressure measurements and/or of risk profiling. For the purpose of this brief paper, we shall mainly use examples and reasonings from our own experience.

Changes in pain perception and pain-related somatosensory evoked potentials in humans produced by exposure to oscillating magnetic fields.

Nociception has been reported to be influenced by exposure to magnetic fields (MFs). The aim of this study was to investigate the effects of 2 h exposure to weak, oscillating MFs on pain perception thresholds and on pain-related somatosensory evoked potentials (SEPs). In 11 healthy volunteers, pain perception thresholds and pain-related SEPs were assessed by intracutaneous electrical stimulation. After sham treatment, pain thresholds significantly increased, whereas after MFs a slight non-significant decrease in thresholds was found. After both treatments pain-related SEP amplitude was reduced, but this decrease was more evident and statistically significant only after MF exposure. The increase found in thresholds after sham exposure may be due to stress-induced analgesia (SIA) and the contrasting behaviour recorded after MF exposure might indicate a suppression of SIA. The significant reduction in pain-related SEP amplitude observed after MF exposure provides the first evidence that human SEPs are influenced by MFs.