Delayed luminescence induced by complex domains in water and in TEOS aqueous solutions

Many recent studies on water have conjectured a complex structure composed of hydrogen bonded low- and high-density domains. In this work the structure of pure water and aqueous solutions of silica gel (TEOS) has been investigated by using delayed luminescence, which has previously shown a significant increase in aqueous salt solutions where low-density domain formation is expected. Photon emission shows an Arrhenius trend with an activation energy in water-TEOS solutions larger than in pure water and salt-water solutions. Moreover, delayed photon emission decay shows an intrinsic lifetime of about 5 μs both in solutions and in pure water that, along with secondary lifetimes induced by the presence of TEOS, could be related to the formation of different domains.

Association between maternal serum high mobility group box 1 levels and pregnancy complicated by gestational diabetes mellitus

BACKGROUND AND AIMS

Gestational diabetes mellitus (GDM), is characterized by chronic, low-grade subclinical inflammation with altered production of cytokines and mediators. Recently, a new protein acting as a "danger signal", high mobility group box 1 (HMGB1), that migrates quickly during electrophoresis, has been identified. The aim of our study was to analyze serum levels of HMGB1 in pregnant women, with or without GDM, in the third trimester of pregnancy to evaluate correlation with insulin resistance and other risk factors for GDM.

METHODS AND RESULTS

Seventy five pregnant women positive to the 75 g oral glucose tolerance test (OGTT) were included in the study group and 48 pregnant women who were negative to the screening test, were randomly selected using a computer-generated randomisation table. A significant positive univariate correlation was observed between serum HMGB1 levels, HOMA-IR index, glycaemia values at OGTT and pre-pregnancy BMI. Moreover, logistic regression analysis showed that serum HMGB1 was independent linked to GDM.

CONCLUSION

Our study demonstrated that HMGB1, a marker of chronic inflammation, is associated to GDM and insulin resistance level, in the third trimester of pregnancy.

High mobility group protein B1: a new biomarker of obesity in pregnant women?

Obesity is associated with an increased risk of an adverse pregnancy outcome. The aim of this study was to analyze the serum levels of high mobility group protein B1 (HMGB1) in obese pregnant women, to assess the role of this protein in the pathogenesis of this disease and to evaluate its possible function as a diagnostic marker for obesity-related complications in obese women. Study participants were randomly selected, from a cohort of pregnant women afferent to our department. A total of 120 women were enrolled in this study: 60 pregnant women had normal body mass index (BMI) and 60 women resulted obese. Pre-pregnancy BMI, weight increase and HMGB1 levels were evaluated for each pregnant woman enrolled. Matching serum HMGB1 levels in two groups, our data evidenced higher levels in the obese women, with a statistically significant difference (p = 0.0023). A significant positive univariate correlation was observed between serum HMGB1 levels and BMI in obese women. HMGB1 serum levels may therefore represent a predictive marker of disease in pregnant women (r = 20.9 and p = 0.0001). Further studies are needed in order to validate the role of this cytokine, with the aim of making it possible to use in clinical practice not only for diagnostic purposes, but especially for the early recognition of complications related to it.

Monitoring molecular response by BCR-ABL, JH and WT-1 in Ph+ all treated with imatinib containing regimen: preliminary report of two cases

We carried out sequential molecular monitoring of different markers on two BCR-ABL positive ALL patients receiving a standard dose induction regimen, which was followed by a maintenance therapy that alternated imatinib and chemotherapy administration. Molecular study was performed at diagnosis, at the end of the induction phase, and then every three months during maintenance therapy. Each marrow sample underwent BCR-ABL analysis (p210 and p190 expression by RT-PCR and Real-time PCR) and monoclonal JH rearrangement analysis, while WT1 gene expression was detected by Real-time PCR. At diagnosis we detected high WT1 expression associated with the presence of both BCR-ABL transcripts and monoclonal JH rearrangement in both patients. Hematological remission, as well as a molecular status characterized by undetectable BCR-ABL expression, normal levels of WT1 expression, and persistence of monoclonal JH rearrangement, were achieved by both patients post-therapy. Follow up of patient 1 showed a progressive increase in WT-1 and in p-190 transcript, which was followed by cytogenetic and hematological relapse. We observed a progressive increase in the p210 transcript without a concomitant increase in WT-1 levels in patient 2. JH rearrangement was detected in all the samples analyzed. The molecular results may indicate the persistence of JH rearranged clonal cells with undetectable BCR-ABL. From a clinical point of view, our preliminary experience suggests that simultaneous analysis of BCR-ABL, JH and WT-1 expression may improve the study of MRD in Ph+ ALL.

Fine structure of the secretory and sensory organs on the cephalon and the first pereionite of Trichoniscus alexandrae Caruso (Crustacea, Isopoda)

Trichoniscus alexandrae Caruso is a blind troglobiont isopod; males possess secretory and sensory organs on the cephalon and 1st pereionite consisting of cuticular pits hosting a tuft of setae and gland openings. Such organs are absent in females. Three types of cuticular structures have been observed: (a) lamellar setae, which likely play a role in protecting the gland openings and favouring the evaporation of secretions; (b) contact chemoreceptors, each provided with six bipolar sensory cells, a scolopale cell and enveloping cells; (c) a secretory cell complex, consisting of a long cylindrical slender duct-forming cell, with the function of transporting to the cuticular surface a secretion produced by two deeper secretory cells. The duct-forming cell is characterized by the presence of numerous microtubules in its cytoplasm, and is provided with a flattened duct. It is suggested that the secretion produced by the secretory cells could serve for sex-recognition.

Haemopoietic growth factors in myelodysplastic syndromes: towards patient-oriented therapy?

Recombinant human erythropoietin (r-EPO) has been used in Myelodysplastic Syndrome (MDS) patients with anaemia since the early nineties. In low-risk MDS patients, other haemopoietic growth factors (HGFs) (granulocyte-colony stimulating factor, G-CSF, granulocyte-macrophage-colony stimulating factor, GM-CSF, and interleukin 3, IL-3) have been used to synergise the effects of r-EPO on erythroid growth and to increase neutrophil count in patients with severe neutropenia. In high-risk MDS, or in patients with post-MDS AML, myeloid HGFs have been used to push blasts into the S-phase, thus increasing their sensitivity to antiblastic drugs. Several trials have shown that r-EPO can increase haemoglobin levels and improve QoL in patients with anaemia associated to MDS. The selection of patients with a high probability of response to HGFs is based on the careful consideration of several clinical and biological parameters, i.e., among others, basal EPO and transfusional needs, disease duration, FAB or WHO subtypes, and IPSS score. Treatment of anaemic MDS patients with HGFs should become "patient oriented" and different types, schedules, and duration of treatment have to be designed according to the specific criteria which most likely predict, for each individual patient, the best chance of responding favourably to therapy.

Cytogenetic and fluorescence in situ hybridization monitoring in Ph+ Chronic Myeloid Leukemia patients treated with imatinib mesylate

Imatinib mesylate determines a favorable clinical course in most Ph positive Chronic Myeloid Leukemia (CML) patients in the chronic phase. Cytogenetic response is usually evaluated by analyzing 20-25 bone marrow metaphases using standard banding techniques. Since this methodology has very low sensitivity, we compared the results obtained by standard banding techniques to the ones obtained by fluorescent in situ hybridization (FISH). This was also done to identify any possible discrepancies between the two techniques. We analyzed 40 Ph+ CML patients in the chronic phase who had previously been treated with interferon alpha (IFNalpha) and who were receiving imatinib. The studies were performed by utilizing the same BM cell samples fixed in acetic acid/methanol, before imatinib therapy and then quarterly. Comparison of cytogenetic results to FISH results at 3 and 6 months of imatinib treatment showed that some patients who had achieved major cytogenetic response (i.e.<35% of examined metaphases showing Ph), showed retention of a higher number of persisting Ph+ cells when examined by FISH, and they did not achieve major FISH response (i.e. <35% of examined interphase cells show the BCR-ABL fusion signal). The discrepancy we found between the results that were obtained by analyzing metaphases and interphase cells disappeared in the subsequent examinations. Moreover, we found that 4 patients (10%) were still Ph+ in all the metaphases we examined even though they achieved excellent clinical response. On the basis of this small series of patients, we suggest that cytogenetic evaluation of patients on imatinib therapy should be performed by utilizing the classic banding technique (metaphase examination), but also by using the FISH technique (interphase examination), since the two methodologies may provide different results.

Acid exposure and altered acid clearance in GERD patients treated for Helicobacter pylori infection

BACKGROUND

After the eradication of Helicobacter pylori, an increased incidence of gastroesophageal reflux disease and acid gastric secretion have been reported.

AIM

To evaluate the effect of Helicobacter pylori-eradication on proximal and distal gastroesophageal reflux and acid clearance in patients with gastroesophageal reflux disease.

PATIENTS AND METHODS

Sixty-eight gastroesophageal reflux disease patients (age range 18-61 years) were studied by upper endoscopy. All underwent esophageal manometry and dual probe 24-h pH-metry.

RESULTS

Percent of time at pH<4 was significantly increased in the proximal esophagus of Helicobacter pylori-eradicated patients compared to Helicobacter pylori-negative (2.4+/-0.5 vs. 1.0+/-0.2; p<0.01); no differences were found in the distal esophagus (14.0+/-3.7 vs. 9.0+/-1.4%, NS). The total number of reflux episodes was significantly higher in the proximal oesophagus of Helicobacter pylori-eradicated patients (37+/-3 vs. 22+/-3, p<0.05). In the distal esophagus, acid clearance was significantly longer, both during total time (1.4+/-0.2 vs. 0.8+/-0.7 min, p<0.01), and in the supine period (8.5+/-2.7 vs. 2.7+/-0.4 min, p<0.05). No differences were reported in the manometric parameters of the two groups of patients.

CONCLUSION

In patients with gastroesophageal reflux disease, Helicobacter pylori eradication is associated with increased acid exposure of the proximal esophagus and delayed distal acid clearance.

Iatrogenic gastroduodenal ulcers during hepatic intra-arterial chemotherapy

BACKGROUND/AIMS

Various percentages of iatrogenic gastroduodenal ulcers during hepatic intra-arterial chemotherapy have been reported in the literature. The aim of this study was to analyze a homogeneous cohort of patients in order to evaluate the evolution and management of this complication.

METHODOLOGY

We retrospectively reviewed the clinical charts of 80 patients with primary or metastatic liver tumors who received 186 hepatic arterial infusion chemotherapy courses of 5-fluorouracil, cisplatin and mitomycin-C. All of the patients complaining of upper gastrointestinal symptoms during or after hepatic arterial infusion underwent esophagogastroduodenoscopy.

RESULTS

Esophagogastroduodenoscopy was performed in 14 patients, all of whom had gastroduodenal ulcers. Two of ten investigated patients were Helicobacter pylori positive. All of the patients were treated with a proton pump inhibitor and five also received major analgesics. All of the ulcers healed without complications. Six patients did not continue with hepatic arterial infusion for reasons other than ulcers. Eight patients received a subsequent hepatic intra-arterial chemotherapy course, five despite the persistence of an active ulcer.

CONCLUSIONS

Iatrogenic gastroduodenal ulcers are probably due to ischemia and the direct toxicity of the anticancer agents. They are Helicobacter pylori independent and do not represent an absolute contraindication for the continuation of hepatic intra-arterial chemotherapy.

Allogeneic bone marrow transplantation (BMT) for adults with acute lymphoblastic leukemia (ALL): predictive role of minimal residual disease monitoring on relapse

We developed a PCR-based method to monitor clonogenic IgH VDJ rearrangement as a possible predictor of relapse in patients with acute B-ALL after allogeneic bone marrow transplantation (BMT). We studied 23 patients at diagnosis, before and after BMT. At the time of BMT, 13 patients were in first complete remission, eight in second complete remission and two in relapse. Four patients were PCR negative before BMT and remained PCR negative also after BMT (-/- pattern). They are still in remission after a median follow-up of 41 months. Nineteen patients were MRD-positive before BMT: three were PCR negative at first determination after BMT (+/- pattern) and maintain remission. Sixteen patients were PCR-positive at first determination after BMT (+/+ pattern): five became PCR negative (+/+/- pattern) (four with chronic graft-versus-host disease (GVHD) and two after donor lymphocyte infusions (DLI)). Nine patients remained PCR-positive (+/+/+ pattern) (four remain in remission, and six relapsed); two patients died before transplant. In conclusion, PCR negative patients before BMT remained negative post-BMT; many pre-BMT positive patients had initial MRD positivity after BMT: 37% of them achieved a molecular remission with cGVHD or DLI.

Control of foot trajectory in human locomotion: role of ground contact forces in simulated reduced gravity

We studied the changes of vertical contact forces, lower limb kinematics, and electromyographic activity (EMG) at different speeds and gravitational loads. To this end healthy subjects were asked to walk on a motorized treadmill while the percentage of body weight unloaded (body weight support, BWS) was modified in steps by means of a well-characterized unloading system. BWS was set at 0, 35, 50, 75, 95, or 100% of body weight. Walking speed was 0.7, 1.1, 2, 3, or 5 km/h. We found that changing BWS between 0 and 95% resulted in drastic changes of kinetic parameters but in limited changes of the kinematic coordination. In particular, the peak vertical contact forces decreased proportionally to BWS; at 95%-BWS they were 20-fold smaller than at 0% and were applied at the forefoot only. Also, there were considerable changes of the amplitude of EMG activity of all tested lower limb muscles and a complex re-organization of the pattern of activity of thigh muscles. By contrast, the corresponding variation of the parameters that describe shape and variability of the foot path was very limited, always <30% of the corresponding values at 0 BWS. Moreover, the planar co-variation of the elevation angles was obeyed at all speed and BWS values. Minimum variance of limb trajectory occurred at 3 km/h. At 100% BWS, subjects stepped in the air, their feet oscillating back and forth just above but never contacting the treadmill. In this case, step-to-step variability of foot path was much greater than at all other BWS levels but was restored to lower values when minimal surrogate contact forces were provided during the "stance" phase. The results did not depend on the specific instruction given to the subject. Therefore we conclude that minimal contact forces are sufficient for accurate foot trajectory control.

Role of diaphragmatic crura and lower esophageal sphincter in gastroesophageal reflux disease: manometric and pH-metric study of small hiatal hernia

The rapid pull-through (RPT) technique during esophageal manometry helps to identify various pressure profiles of hiatal hernia (HH), based on the presence of two high pressure zones: the diaphragmatic crura (DC) and the lower esophageal sphincter (LES). Our aim was to correlate different HH profiles with frequency of reflux episodes in patients with gastroesophageal reflux disease (GERD). Seventy-eight patients with GERD and HH underwent esophageal manometry with RPT and were grouped according to the prevalent pressure profile of HH. Twenty-four-hour pH-metry served to quantify traditional (TR) and nontraditional refluxes (drop of 1 pH unit with pH > 4 or pH < 4 and time < 5 sec) (NTR) during total, upright, and recumbent periods. The group with a prevalent "flat" HH profile, representing LES and DC impairment, had significantly more TRs in total time of reflux (P < 0.01) and in recumbent and upright periods (P < 0.05) compared to the group with a prevalence of the two pressure peaks, corresponding to LES and DC efficiency. However, the group with the flat profile had significantly more NTRs + TRs than the group with pressure peaks in total time (P < 0.01) and recumbent position (P < 0.001) but not in the upright position. Hiatal hernia predisposes to GERD, but only the associated impairment of the LES and diaphragmatic crura pressures represents a condition of high risk for gastroesophageal reflux events.

Functional dyspepsia symptoms, gastric emptying and satiety provocative test: analysis of relationships

BACKGROUND

The correlation between symptoms and observed impaired function in functional dyspepsia is still inconsistent. The aims of the study were to obtain a measure of satiety by a meal test; to verify whether this compares with severity of symptoms assessed using a reproducible questionnaire; and to correlate the parameters of satiety test and gastric emptying with all the dyspeptic symptoms.

METHODS

Fifty-two functional dyspepsia patients reported their symptoms on a standardized questionnaire that considered belching, bloating, early satiety, epigastric pain and burning, nausea, postprandial fullness and vomiting. They were monitored for gastric emptying of a solid caloric meal using a radionuclide technique and underwent a test to quantify meal-induced satiety by a liquid caloric meal.

RESULTS

The number of kilocalories ingested during the satiety test until the occurrence of maximum satiety in healthy subjects was 110% higher than in the dyspeptic group (mean +/- s(mean): 1110 +/- 23 versus 532 +/- 56; P < 0.01). We found a significant positive correlation between gastric emptying rate and kcal of the satiety test (P < 0.01; r = 0.428). Logistic regression showed a significant inverse association between severity of early satiety-coded as absent, mild, moderate or severe, kcal of meal test (P = 0.01), and gastric emptying lag phase (P = 0.03). Bloating was associated directly with t(1/2) of gastric emptying (P = 0.03) and inversely with lag phase (P = 0.02).

CONCLUSIONS

The satiety test gives a fine numerical measure of satiety and confirms the results of a symptoms questionnaire. Our study showed an indirect correlation between severity of early satiety--as measured by the satiety test, and gastric emptying rate, as well as an association between bloating and delayed gastric emptying.

Lymphoplasmacytic lymphoma/immunocytoma: towards a disease-targeted treatment?

Lymphoplasmacytic-lymphoplasmacytoid lymphoma (LPL)/Waldenstrom's macroglobulinemia (WM) or immunocytoma (IMC) consists of diffuse proliferation of small mature B lymphocytes, plasmacytoid lymphocytes, and plasma-cells. The nosographic definition includes the lack of histological, immunophenotypic, cytogenetic, and molecular markers considered specific of other types of lymphoma. The cells show surface Ig (usually IgM), B-cell-associated antigens and display the CD5-, CD23- and CD10- phenotype, which allows for differential diagnosis from B-CLL and mantle cell lymphoma. t(9;14)(p13;q32) chromosomal translocation has been found in 50% of all LPL cases. The cytogenetic rearrangement juxtaposes the PAX-5 gene, which encodes for an essential transcription factor for B-cell proliferation and differention, to the Ig heavy chain gene. The combination of chlorambucil and prednisone holds as the standard treatment and seems to guarantee good control of the disease in most patients. Similar therapeutic results have been described with the combination of cyclophosphamide, vincristine, prednisone with (CHOP) or without doxorubicin (CVP), or with a combination of other alkylating agents and prednisone. Nucleoside analogues, alone or in combination with alkylating agents and anthracyclines, provide good salvage therapy for IMC and being increasingly employed as first line therapy. In a multicentric European trial Foran et al. administered the chimeric anti-CD20-monoclonal antibody (Rituximab) to 28 patients with previously treated IMC. Seven out of 25 evaluable patients (28%) achieved a partial response. Byrd et al. examined the outcome of 7 previously treated WM patients who received weekly infusions of rituximab (375 mg/m2). Therapy was well tolerated by all patients, and there was no decrease in cellular immune function, or significant infectious morbidity. Partial responses were noted in three of these patients, including two with fludarabine-refractory disease. These data suggest that rituximab exerts clinical activity on heavily pre-treated patients with WM. Furthermore, Weide et al. first reported that WM-associated polyneuropathy can be treated effectively with a combination of chemotherapy and the anti-CD20 monoclonal antibody rituximab. Most published trials exploring the efficacy of high dose treatment as salvage therapy for relapsed or refractory low grade non Hodgkin's lymphoma have included prevalently follicular or lymphocytic lymphomas. In selected high risk patients radioimmunotherapy with autologous stem-cell rescue, and myeloablative therapy followed either by autologous stem cell transplantation (SCT) or allogeneic SCT might represent an alternative strategy.

Molecular analysis of patients with relapsed or refractory intermediate-high grade non-Hodgkin's lymphoma with bone marrow infiltration undergoing peripheral blood progenitor cell transplantation

BACKGROUND AND OBJECTIVES

IgH gene rearrangement studies with a polymerase chain reaction (PCR) technique can detect the persistence of clonal cells at molecular level during the remission phase. This persistence of clonal cells can be used to establish the relationship between minimal residual disease (MRD) and clinical outcome. We have developed a three-step single strand conformational polymorphism PCR strategy which is able to detect clonal B lymphoid cells at a frequency as low as 1 clonal cell in 10(6) normal cells.

DESIGN AND METHODS

Twenty patients with intermediate or high-grade B non-Hodgkin's lymphoma (NHL) were evaluated. Patients were pre-treated with a median of two (range 1-4) conventional chemotherapy lines before high-dose cyclophosphamide (HDCY). All patients had their bone marrow (BM) involved by disease (median 10%; range 5-50%). Nineteen patients were offered high-dose therapy followed by peripheral blood progenitor cells (PBPC) autografting.

RESULTS

MRD analysis was performed for each patient at the end of conventional chemotherapy and every three months after high dose therapy. All these patients achieved complete response (CR) after high dose therapy (HDT). Six patients relapsed after a median time of 24.5 months. All the studied apheresis samples were positive at the molecular analysis. All 6 patients still positive at the molecular analysis after PBPC autografting relapsed. The remaining 13 patients who were negative maintained CR.

INTERPRETATION AND CONCLUSIONS

Whereas the detection of clonal cells in the apheresis samples did not predict an unfavorable outcome, the disappearance of the clonal rearranged band from the BM sample after HDT proved to be a favorable prognostic factor and was associated with long-lasting disease-free status

Detection of minimal residual disease in B-lymphoproliferative disorders: a three step SSCP-PCR method

The most recent therapeutic approaches can improve the outcome of B-cell neoplasia. By PCR analysis we amplify tumor specific DNA sequences of clonal IgH rearrangement from a limited number of malignant cells against a background of normal B cells. Recently described PCR based techniques for tracking minimal residual disease (MRD) in B lymphoproliferative disorders have given promising but discordant results, with significant variations in the sensitivity and specificity of the procedures. We have developed a three step single strand conformational polymorphism polymerase chain reaction (SSCP-PCR) strategy which is able to detect clonal malignant cells in B lymphoproliferative disorders at a frequency as low as 1 in 10(6) cells. Since this method is simple, rapid, reliable and as specific as ASO-PCR, it could be especially useful in monitoring patients affected by B lymphoproliferative disorders in complete haematological and immunophenotypic remission.

Baroreflex and oscillation of heart period at 0.1 Hz studied by alpha-blockade and cross-spectral analysis in healthy humans

1. Parameters derived from frequency-domain analysis of heart period and blood pressure variability are gaining increasing importance in clinical practice. However, the underlying physiological mechanisms in human subjects are not fully understood. Here we address the question as to whether the low frequency variability (approximately 0.1 Hz) of the heart period may depend on a baroreflex-mediated response to blood pressure oscillations, induced by the alpha-sympathetic drive on the peripheral resistance. 2. Heart period (ECG), finger arterial pressure (Finapres) and respiratory airflow were recorded in eight healthy volunteers in the supine position with metronome respiration at 0.25 Hz. We inhibited the vascular response to the sympathetic vasomotor activity with a peripheral alpha-blocker (urapidil) and maintained mean blood pressure at control levels with angiotensin II. 3. We performed spectral and cross-spectral analysis of heart period (RR) and systolic pressure to quantify the power of low- and high-frequency oscillations, phase shift, coherence and transfer function gain. 4. In control conditions, spectral analysis yielded typical results. In the low-frequency range, cross-spectral analysis showed high coherence (> 0.5) and a negative phase shift (-65.1 +/- 18 deg) between RR and systolic pressure, which indicates a 1-2 s lag in heart period changes in relation to pressure. In the high-frequency region, the phase shift was close to zero, indicating simultaneous fluctuations of RR and systolic pressure. During urapidil + angiotensin II infusion the low-frequency oscillations of both blood pressure and heart period were abolished in five cases. In the remaining three cases they were substantially reduced and lost their typical cross-spectral characteristics. 5. We conclude that in supine rest conditions, the oscillation of RR at low frequency is almost entirely accounted for by a baroreflex mechanism, since it is not produced in the absence of a 0.1 Hz pressure oscillation. 6. The results provide physiological support for the use of non-invasive estimates of the closed-loop baroreflex gain from cross-spectral analysis of blood pressure and heart period variability in the 0.1 Hz range.

Baroreflex and oscillation of heart period at 0.1 Hz studied by alpha-blockade and cross-spectral analysis in healthy humans

1. Parameters derived from frequency-domain analysis of heart period and blood pressure variability are gaining increasing importance in clinical practice. However, the underlying physiological mechanisms in human subjects are not fully understood. Here we address the question as to whether the low frequency variability (approximately 0.1 Hz) of the heart period may depend on a baroreflex-mediated response to blood pressure oscillations, induced by the alpha-sympathetic drive on the peripheral resistance. 2. Heart period (ECG), finger arterial pressure (Finapres) and respiratory airflow were recorded in eight healthy volunteers in the supine position with metronome respiration at 0.25 Hz. We inhibited the vascular response to the sympathetic vasomotor activity with a peripheral alpha-blocker (urapidil) and maintained mean blood pressure at control levels with angiotensin II. 3. We performed spectral and cross-spectral analysis of heart period (RR) and systolic pressure to quantify the power of low- and high-frequency oscillations, phase shift, coherence and transfer function gain. 4. In control conditions, spectral analysis yielded typical results. In the low-frequency range, cross-spectral analysis showed high coherence (> 0.5) and a negative phase shift (-65.1 +/- 18 deg) between RR and systolic pressure, which indicates a 1-2 s lag in heart period changes in relation to pressure. In the high-frequency region, the phase shift was close to zero, indicating simultaneous fluctuations of RR and systolic pressure. During urapidil + angiotensin II infusion the low-frequency oscillations of both blood pressure and heart period were abolished in five cases. In the remaining three cases they were substantially reduced and lost their typical cross-spectral characteristics. 5. We conclude that in supine rest conditions, the oscillation of RR at low frequency is almost entirely accounted for by a baroreflex mechanism, since it is not produced in the absence of a 0.1 Hz pressure oscillation. 6. The results provide physiological support for the use of non-invasive estimates of the closed-loop baroreflex gain from cross-spectral analysis of blood pressure and heart period variability in the 0.1 Hz range.

Influence of leg muscle vibration on human walking

We studied the effect of vibratory stimulation of different leg muscles [bilateral quadriceps (Q), hamstring (HS) muscles, triceps surae (TS), and tibialis anterior (TA)] in seven normal subjects during 1) quiet standing, 2) stepping in place movements, and 3) walking on the treadmill. The experiments were performed in a dimly illuminated room, and the subjects were given the instruction not to resist the applied perturbation. In one condition the velocity of the treadmill was controlled by a feedback from the subject's current position. In normal standing, TA vibration elicited a prominent forward body tilt, whereas HS and TS vibration elicited backward trunk or whole body inclination, respectively. Q vibration had little effect. During stepping in place, continuous HS vibration produced an involuntary forward stepping at about 0.3 m s(-1) without modifying the stepping frequency. When the subjects (with eyes closed) kept a hand contact with an external still object, they did not move forward but perceived an illusory forward leg flexion relative to the trunk. Q, TS, and TA vibration did not cause any systematic body translation nor illusory changes in body configuration. In treadmill locomotion, HS vibration produced an involuntary steplike increase of walking speed (by 0.1-0.6 m.s(-1)). Continuous vibration elicited larger speed increments than phasic stimulation during swing or stance phase. For phasic stimulation, HS vibration tended to be more effective when applied during swing than during stance phase. Q, TA, and TS vibration had little if any effect. Vibration of thigh muscles altered the walking speed depending on the direction of progression. During backward locomotion, the walking speed tended to decrease after HS vibration, whereas it significantly increased after Q vibration. Thus the influence of leg muscle vibration on stepping in place and locomotion differed significantly from that on normal posture. We suggest that the proprioceptive input from thigh muscles may convey information about the velocity of the foot movement relative to the trunk.

Neck muscle vibration makes walking humans accelerate in the direction of gaze

We studied the effect of the continuous vibration of symmetrical dorsal neck muscles in seven normal subjects during (a) quiet standing, (b) stepping in place movements and (c) walking on the treadmill. The experiments were performed in a darkened room and the subjects were given the instruction not to resist the applied perturbation. In one condition the velocity of the treadmill was controlled by feedback from the subject's current position. Head, trunk and leg motion were recorded at 100 Hz. In normal standing, neck vibration elicited a prominent forward body sway. During stepping in place, neck vibration produced an involuntary forward stepping at about 0.3 m s-1 without modifying the stepping frequency. If the head was turned horizontally 45 and 90 deg to the right or to the left, neck muscle vibration caused stepping approximately in the direction of the head naso-occipital axis. For lateral eye deviations, the direction of stepping was roughly aligned with gaze direction. In treadmill locomotion, neck vibration produced an involuntary step-like increase of walking speed (by 0.1-0.6 m s-1), independent of the initial walking speed. During backward locomotion, the walking speed tended to decrease during neck vibration. Thus, continuous neck vibration evokes changes in the postural reference during quiet standing and in the walking speed during locomotion. The results suggest that the proprioceptive input from the neck is integrated in the control of human posture and locomotion and is processed in the context of a viewer-centred reference frame.

Spatial, not temporal cues drive predictive orienting movements during navigation: a virtual reality study

A fundamental property of the human brain is the ability to make predictions of future sensory and motor events. We have recently found that steering manoeuvres when walking along curvilinear trajectories are controlled by an anticipatory guidance of the direction of head (and eyes). However it is unclear whether a time-related or space-related signal triggers such anticipatory head orienting movements. By simulating navigation along a multi-legged virtual corridor we show that anticipatory orienting movements are triggered (in standing subjects) by reaching specific locations rather than by the time to the approaching corridor's bend. Similar to what happens in car driving, specific spatial features of the route rather than time to collision seem to drive steering.

Interactions between posture and locomotion: motor patterns in humans walking with bent posture versus erect posture

Human erect locomotion is unique among living primates. Evolution selected specific biomechanical features that make human locomotion mechanically efficient. These features are matched by the motor patterns generated in the CNS. What happens when humans walk with bent postures? Are normal motor patterns of erect locomotion maintained or completely reorganized? Five healthy volunteers walked straight and forward at different speeds in three different postures (regular, knee-flexed, and knee- and trunk-flexed) while their motion, ground reaction forces, and electromyographic (EMG) activity were recorded. The three postures imply large differences in the position of the center of body mass relative to the body segments. The elevation angles of the trunk, pelvis, and lower limb segments relative to the vertical in the sagittal plane, the ground reaction forces and the rectified EMGs were analyzed over the gait cycle. The waveforms of the elevation angles along the gait cycle remained essentially unchanged irrespective of the adopted postures. The first two harmonics of these kinematic waveforms explain >95% of their variance. The phase shift but not the amplitude ratio between the first harmonic of the elevation angle waveforms of adjacent pairs was affected systematically by changes in posture. Thigh, shank, and foot angles covaried close to a plane in all conditions, but the plane orientation was systematically different in bent versus erect locomotion. This was explained by the changes in the temporal coupling among the three segments. For walking speeds >1 m s(-1), the plane orientation of bent locomotion indicates a much lower mechanical efficiency relative to erect locomotion. Ground reaction forces differed prominently in bent versus erect posture displaying characteristics intermediate between those typical of walking and those of running. Mean EMG activity was greater in bent postures for all recorded muscles independent of the functional role. The waveforms of the muscle activities and muscle synergies also were affected by the adopted posture. We conclude that maintaining bent postures does not interfere either with the generation of segmental kinematic waveforms or with the planar constraint of intersegmental covariation. These characteristics are maintained at the expense of adjustments in kinetic parameters, muscle synergies and the temporal coupling among the oscillating body segments. We argue that an integrated control of gait and posture is made possible because these two motor functions share some common principles of spatial organization.

Time course of gaze influences on postural responses to neck proprioceptive and galvanic vestibular stimulation in humans

We have previously shown that postural responses to vibration of neck dorsal muscles (NS) and to galvanic stimulation of the vestibular system (GS) are influenced by the direction of gaze. Here, we describe the time course of this effect. We found that eye orienting movements during NS induce shifts of body inclination toward the direction of gaze with a latency of about 2 s: the time course is smooth and a steady state is attained after about 5 s from eye movements. If eye eccentricity is maintained and NS or GS are sequentially repeated for as long as 2 min, the direction of sway drifts in the direction opposite to eye deviation. The findings reveal that the frames of reference for the control of posture may have a dynamic nature.

Manometric study of hiatal hernia and its correlation with esophageal peristalsis

The pathogenesis of gastroesophageal reflux disease (GERD) is considered multifactorial, but alterations of the esophagogastric junction (EGJ) and hiatal hernia play a prominent role. The correlations between hiatal hernia and the other pathogenetic factors are as yet unclear, and they need to be investigated by a methodological approach based on new anatomic and functional criteria. Our aim was to study, by stationary manometry, the relationships between small reducible hiatal hernia, identified by endoscopy, and esophageal peristalsis, in patients with and without GERD. According to the absence or presence of esophagitis (E), and the absence or presence of hiatal hernia (H), 58 subjects were divided into four groups: controls 10; H 14; E 10; and HE 24. Stationary manometry was performed by the rapid pull-through (RPT) technique, with catheter water perfused, to study the lower esophageal high pressure zone [lower esophageal sphincter (LES) and diaphragmatic crura] and the parameters of esophageal peristalsis. In patients with hiatal hernia, the various combinations of peak and/or deflection of manometric line pressure identified five EGJ profiles, only one of which reveals (by one-peak profile due to superimposed LES and diaphragmatic crura) the reducibility of the hernia. The frequency of the five profiles was calculated in the HE and H groups: a two-peak profile was significantly more prevalent in these patients, although less so in the group with esophagitis. In E patients the distal amplitude and the distal propagation of esophageal waves were significantly lower than in the other three groups (P < 0.05 vs controls and group HE; P < 0.01 vs group H). Furthermore, the distal amplitude was significantly higher in the group H than in the HE (P < 0.01). Our results show a better definition of hiatal hernia morphology, via the RPT technique, disclosing five pressure profiles. In addition, a significant link was found between small reducible hiatal hernia without GERD and wave amplitude of the distal esophagus. The amplification of peristaltic clearing may be considered the initial protective process against acid reflux; the breakdown of this mechanism may trigger the pathological sequence of GERD.

Effect of gaze on postural responses to neck proprioceptive and vestibular stimulation in humans

1. We studied the effect of gaze orientation on postural responses evoked by vibration of neck dorsal muscles or by galvanic stimulation of the vestibular system during quiet standing in healthy humans. Various gaze orientations were obtained by different combinations of horizontal head-on-feet (-90, -45, 0, 45, 90 deg) and eye-in-orbit (-30, 0, 30 deg) positions. The instantaneous centre of foot pressure was recorded with a force platform. 2. With a symmetrical position of the vibrator relative to the spine, neck muscle vibration elicited a body sway in the direction of the head naso-occipital axis when the eyes were aligned with it. The same result was obtained both during head rotations and when the head and trunk were rotated together. 3. For lateral eye deviations, the direction of the body sway was aligned with gaze orientation. The effect of gaze was present both with eyes open and eyes closed. After long-lasting (1 min) lateral fixation of the target the effect of gaze decreased significantly. 4. Postural responses to galvanic vestibular stimulation tended to occur orthogonal to the head naso-occipital axis (towards the anodal ear) but in eight of the 11 subjects the responses were also biased by the direction of gaze. 5. The prominent effect of gaze in reorienting automatic postural reactions indicates that both neck proprioceptive and vestibular stimuli are processed in the context of visual control of posture. The results point out the importance of a viewer-centred frame of reference for processing multisensory information.

Motor Patterns in Walking

Despite the fact that locomotion may differ widely in mammals, common principles of kinematic control are at work. These reflect common mechanical and neural constraints. The former are related to the need to maintain balance and to limit energy expenditure. The latter are related to the organization of the central pattern-generating networks.

Replication of passive whole-body linear displacements from inertial cues. Facts and mechanisms

Using path integration, normal subjects should be able to compute the distance of a traveled path even from the sole inertial sensory input. Blindfolded subjects were submitted to a passive linear forward displacement along 2 to 10 m. Their task was to replicate the traveled distance, still blindfolded, by driving the vehicle they were seated upon using a joystick that controlled linear speed. Subjects replicated both the length and the velocity profile of the passive travel, suggesting that a dynamic record of experienced motion is stored in memory. Even when the replication of passive motion dynamics was made impossible, the subjects could still replicate the displacement. The results are explained by a dynamic feedback model that performs a running comparison between the perceived instantaneous displacement of the ongoing motion and the displacement derived from a spatiotemporal record of perceived passive motion. A multimodal acceleration-related sensory input is transformed into a displacement-related perception through double time-integration.

Basal ganglia and gait control: apomorphine administration and internal pallidum stimulation in Parkinson's disease

Gait coordination was analyzed (four-camera 100 Hz ELITE system) in two groups of idiopathic Parkinson disease (PD) patients. Five patients underwent continuous infusion of apomorphine and were recorded in two different sessions (APO OFF and APO ON) in the same day. Three patients with a previous chronic electrode implantation in both internal globi pallidi (GPi) were recorded in the same experimental session with the electrodes on and off (STIM ON and STIM OFF). The orientation of both the trunk and the lower-limb segments was described with respect to the vertical in the sagittal plane. Lower-limb inter-segmental coordination was evaluated by analyzing the co-variation between thigh, shank, and foot elevation angles by means of orthogonal planar regression. At least 30 gait cycles per experimental condition were processed. We found that the trunk was bent forward in STIM OFF, whereas it was better aligned with the vertical in STIM ON in both PD groups. The legs never fully extended during the gait cycle in STIM OFF, whereas they extended before heel strike in STIM ON. The multisegmental coordination of the lower limb changed almost in parallel with the changes in trunk orientation. In STIM OFF, both the shape and the spatial orientation of the planar gait loops (thigh angle vs. shank angle vs. foot angle) differed from those of physiological locomotion, whereas in STIM ON the gait loop tended to resume features closer to the control. Switching the electrodes on and off in patients with GPi electrodes resulted in quasi-parallel changes of the trunk inclination and of the planar gait loop. The bulk of the data suggest that the basal-ganglia circuitry may be relevant in locomotion by providing an appropriate spatio-temporal framework for the control of posture and movement in a gravity-based body-centered frame of reference. Pallido-thalamic and/or pallido-mesencephalic pathways may influence the timing of the inter-segmental coordination for gait.

Non-specific directional adaptation to asymmetrical visual-vestibular stimulation

Subjective estimates of passive whole-body rotations in darkness were evaluated before and after exposure to asymmetrical incoherent visual-vestibular stimulation (VVS). Two subjects who showed large capacity for adaptation to symmetrical incoherent VVS were enrolled in the study. Strikingly, after 45 min of asymmetrical left-right VVS, perception of rotation decreased equally for rotations to the right and to the left indicating that the calibration of vestibular sensory input for spatial orientation did not undergo a directional specific control.

Motor patterns for human gait: backward versus forward locomotion

Seven healthy subjects walked forward (FW) and backward (BW) at different freely chosen speeds, while their motion, ground reaction forces, and electromyographic (EMG) activity from lower limb muscles were recorded. We considered the time course of the elevation angles of the thigh, shank, and foot segments in the sagittal plane, the anatomic angles of the hip, knee, and ankle joints, the vertical and longitudinal ground reaction forces, and the rectified EMGs. The elevation angles were the most reproducible variables across trials in each walking direction. After normalizing the time course of each variable over the gait cycle duration, the waveforms of all elevation angles in BW gait were essentially time reversed relative to the corresponding waveforms in FW gait. Moreover, the changes of the thigh, shank, and foot elevation covaried along a plane during the whole gait cycle in both FW and BW directions. Cross-correlation analysis revealed that the phase coupling among these elevation angles is maintained with a simple reversal of the delay on the reversal of walking direction. The extent of FW-BW correspondence also was good for the hip angle, but it was smaller for the knee and ankle angles and for the ground reaction forces. The EMG patterns were drastically different in the two movement directions as was the organization of the muscular synergies measured by cross-correlation analysis. Moreover, at any given speed, the mean EMG activity over the gait cycle was generally higher in BW than in FW gait, suggesting a greater level of energy expenditure in the former task. We argue that conservation of kinematic templates across gait reversal at the expense of a complete reorganization of muscle synergies does not arise from biomechanical constraints but may reflect a behavioral goal achieved by the central networks involved in the control of locomotion.

Eye-head coordination for the steering of locomotion in humans: an anticipatory synergy

We investigated head and gaze orientation in six healthy volunteers walking along 90 degrees corner trajectories, both at light and with eyes closed. We found that head and eyes systematically deviated toward the future direction of the curved trajectory. Anticipation lead was about 1 s. Strikingly, the same behaviour was observed in darkness. In backward (BW) locomotion along the trajectory (from end- to start-point), gaze deviated toward the opposite direction, such that the forward locomotor pattern did not appear time-reversed. Orienting movements displayed higher amplitude, reproducibility and time lead in the forward (FW) direction at light. We suggest that anticipatory orienting synergies belong to the behavioural repertoire of human navigation and may reflect the need to prepare a stable reference frame for intended action.

Development of anticipatory orienting strategies during locomotor tasks in children

Some basic problems related to the development of goal-directed locomotion in humans are reviewed here. A preliminary study is presented which was aimed at investigating the emergence of anticipatory head orienting strategies during goal-directed locomotion in children. Eight children ranging from 3.5 to 8 years had to walk along a 90 degrees right corner trajectory to reach a goal, both in light and in darkness. The instantaneous orientation in space of the head, trunk, hips and left foot antero/posterior axes was computed by means of an ELITE four-TV camera, 100 Hz system. The results showed that predictive head orienting movements can occur also in the youngest children. The head starts to rotate toward the goal before the corner point of the trajectory is reached. In children, the head peak rotation coincides with the trajectory corner while in adults the peak is attained before. In children, the walking speed is largely decreased in darkness. The results suggest that feedforward control of goal-directed locomotion appears very early in gait development and becomes increasingly important afterwards.

Spatial orientation in humans: perception of angular whole-body displacements in two-dimensional trajectories

Vestibular perception of whole-body passive rotation in the horizontal plane was studied by applying two-dimensional (2D) motion to eight blindfolded healthy volunteers: pure rotations in place, corner-like trajectories and arcs of a circular trajectory were randomly applied by means of a remotely controlled robot. Angles embedded in the 2D trajectories were 45 degrees, 90 degrees, 135 degrees and 180 degrees. Stimulation of semicircular canals was the same for all trajectories but was accompanied by concurrent otolith stimulation during circular motion. Subjects participated in two successive experimental sessions. In the first session they were instructed to use a pointer to reproduce the total angular displacement after the motion (REPRODUCTION); in the second session they had to keep pointing towards a remote (15 m) memorised target during the motion (TRACKING). In REPRODUCTION subjects tended to overestimate their rotation angle by 28 +/- 11% (mean +/- SD). There was no systematic effect of the trajectory. Overestimation also occurred when subjects were required to rotate in darkness by 180 degrees (by controlling a joystick). In TRACKING there was virtually no overestimation (6 +/- 17%) and the movement of the pointer matched the dynamics of angular motion. We conclude that (a) the brain can separate and memorise the angular component of complex 2D motion; however, a large inter-individual variability in estimating its amplitude exists; (b) in the range of linear accelerations used in the study, no appreciable effect of otolith-canal perceptual interaction was shown; (c) angular displacements can be dynamically transformed into matched pointing movements; (d) overestimation seems to be typical of delayed judgements of angular displacement and of self-controlled rotations in place. This could be due to the characteristics of the physiological calibration of the vestibular input.

The contribution of otoliths and semicircular canals to the perception of two-dimensional passive whole-body motion in humans

1. Perception of two-dimensional (2-D) whole-body passive motion in the horizontal plane was studied in twelve blindfolded healthy volunteers: pure rotation in place (180 deg), linear motion (4.5 m) and a semicircular trajectory (radius, 1.5 m; angular acceleration, 0.2 rad s-2) were applied in random sequence by means of a remote-controlled robot equipped with a racing-car seat. The seat orientation in the horizontal plane was controlled by the experimenter, independent of the robot trajectory. Thus different degrees of otolith-canal interaction were obtained. The maximal linear acceleration during the semicircular trajectory was 0.1 g; however, the linear acceleration vector was complex as it rotated relative to the subject's head. 2. In the first of two sessions, subjects were instructed to maintain an angular pointer oriented towards a remote (15 m) previously seen target during the passive movements. In the second session they had to make a drawing of the path of the perceived trajectory, after the movement was finished. 3. The results showed that, on average, the movement of the pointer matched the dynamics of the rotatory component of the 2-D motion well. This suggests that, in the range of linear accelerations used in this study, no appreciable influence of otolith input on canal-mediated perception of angular motion occurred. 4. The curvature of the drawn paths was mostly explained by the input to the semicircular canals. Subjects' reconstruction of motion did not account for the directional dynamics of the input to the otoliths occurring during passive motion. 5. This finding proves that reconstructing trajectory in space does not imply a mathematically perfect transformation of the linear and angular motion-related inputs into a Cartesian or polar 2-D representation. Physiological constraints on the interaction between motion direction and change of heading play an important role in motion perception.

Spatial memory and path integration studied by self-driven passive linear displacement. I. Basic properties

According to path integration, the brain is able to compute the distance of a traveled path. In this research we applied our previously reported method for studying memory of linear distance, a crucial mechanism in path integration; our method is based on the overt reconstruction of a passive transport. Passive transport is a special case of navigation in which no active control is performed. Blindfolded subjects were first asked to travel 2 m forward, in darkness, by driving with a joystick the robot on which they were seated. The results show that all subjects but two undershot this distance, i.e., overestimated their own displacement. Then, subjects were submitted to a passive linear forward displacement along 2, 4, 6, 8, or 10 m, and had to reproduce the same distance, still blindfolded. The results show that the distance of the stimulus was accurately reproduced, as well as stimulus duration, peak velocity, and velocity profile. In this first condition, the imposed velocity profile was triangular and therefore stimulus distance and duration were correlated. In a second condition, it was shown that distance was correctly reproduced also when the information about stimulus duration was kept constant. Here, different velocity profiles were used as stimuli, and most subjects also reproduced the velocity profile. Statistical analyses indicated that distance was not reproduced as a consequence of duration, peak velocity, or velocity profile reproduction, but was uniquely correlated to stimulus distance. The previous hypothesis of a double integration of the otolith signal to provide a distance estimate can explain our results. There was a large discrepancy between the accuracy with which the subjects matched the velocity profiles and that of distance reproduction. It follows that, whereas the dynamics of passive motion are stored and available to further use, distance is independently estimated. It is concluded that vestibular and somatosensory signals excited by passive transport can be used to build a dynamic as well as a static representation of the traveled path. We found a close quantitative similarity between the present findings on distance reproduction and those obtained from active locomotion experiments in which the same paradigm was used. This resemblance suggests that the two types of navigation tasks draw on common physiological processes and extends the relevance of our results to naturally occurring path integration.

Integration of somatosensory and vestibular inputs in perceiving the direction of passive whole-body motion

We investigated the contribution of somatosensory and vestibular inputs in the detection of the direction of linear whole-body displacement (1.5 m) at low levels of linear acceleration (peak acceleration 0.2 m/s2), in normal subjects. Subjects sat on a mobile robot wearing opaque goggles and headphones. They indicated the direction of motion by using a laser pointer held by the right hand at the level of the chin. Adaptation to a long-lasting static head turn (45 degrees to the right) was used to modify the perceived head orientation relative to the trunk. After about 15 min the head and trunk were perceived to be aligned with each other. After adaptation subjects pointed in the same direction as in the control condition in spite of the change in the perception of the head orientation. Because space orientated reactions to vestibular stimuli were previously shown to be coded in the perceived head reference frame, these results indicate that somatosensory cues are also integrated in the perception of linear motion. Unexpectedly, after adaptation, trunk and head perceived orientations were attracted toward the direction of the imposed motion. This suggests that the internal representation of body configuration depends also upon available cues from the extrapersonal space.