Risk factors for voluntary interruption of pregnancy and possible preventive public health actions.

INTRODUCTION: Voluntary interruption of pregnancy (VIP) is one of the most frequent healthcare procedures in the world and a Public Health concern in many countries, especially after liberalization of the abortion laws. The study has been carried out to identify the factors that still influence a fraction of female population towards abortion in the absence of fetal malformations. METHODS: We conducted a cross-sectional study in the period 2012-2016. The survey was carried out on all VIPs performed at the Gynecology and Obstetrics Unit of the University Hospital "G. Martino" in Messina, Italy. RESULTS: The analyzed sample consisted of 1131 women, aged between 16 and 50 years. Only 4% of VIPs was due to a diagnosis of fetal malformation. In relation to the presence or absence of fetal malformations as the possible reason for VIP, the sample was split up into two groups and the socio-demographic characteristics were considered. VIPs in the absence of malformations were significantly more frequent in younger women with a lower educational level, in unmarried and unemployed women and in women who already had children. These results were confirmed to Pearson test that indicated that all these variables were related to VIP in the absence of malformations. CONCLUSIONS: Based on our results, it is crucial to further prevent requests for VIPs through information and sex education programs for adolescents in schools and consultants, and responsible procreation promotion programs.

Campylobacter: from microbiology to prevention.

In last years, Campylobacter spp has become one of the most important foodborne pathogens even in high-income countries. Particularly, in Europe, Campylobacteriosis is, since 2005, the foodborne disease most frequently notified and the second in USA, preceded by the infection due to Salmonella spp. Campylobacter spp is a commensal microorganism of the gastrointestinal tract of many wild animals (birds such as ducks and gulls), farm animals (cattle and pigs) and companion animals (such as dogs and cats) and it is responsible for zoonoses. The transmission occurs via the fecal-oral route through ingestion of contaminated food and water. The disease varied from a watery diarrhea to a severe inflammatory diarrhea with abdominal pain and fever and can be burdened by some complications. The main recognized sequelae are Guillain-Barré Syndrome (GBS), the Reactive Arthritis (REA) and irritable bowel syndrome (IBS). Recently, many cases of Campylobacter spp isolated from human infections, showed an important resistance to various antibiotics such as tetracyclines and fluoroquinolones. For these reasons, the prevention of this infection plays an essential role. Many preventive measures exist to limit the transmission of the pathogens and the subsequent disease such as the health surveillance, the vaccination of the poultry and the correct food hygiene throughout the entire production chain. A global surveillance of Campylobacteriosis is desirable and should include data from all countries, including notifications of cases and the microbiological data typing of strains isolated from both human and animal cases.

Humidifiers for oxygen therapy: what risk for reusable and disposable devices?

INTRODUCTION: Nosocomial pneumonia accounts for the vast majority of healthcare-associated infections (HAI). Although numerous medical devices have been discussed as potential vehicles for microorganisms, very little is known about the role played by oxygen humidifiers as potential sources of nosocomial pathogens. The purpose of this research was to evaluate the safety of the reuse of humidifiers by analysing the rate of microbial contamination in reusable and disposable oxygen humidifiers used during therapy, and then discuss their potential role in the transmission of respiratory pathogens. METHODS: Water samples from reusable and disposable oxygen humidifiers were collected from different wards of the University Hospital of Messina, Italy, where nosocomial pneumonia has a higher incidence rate due to the "critical" clinical conditions of inpatients. In particular, we monitored the Internal Medicine and Pulmonology wards for the medical area; the General Surgery and Thoracic and Cardiovascular Surgery wards for the surgical area and the Intensive Care Unit and Neonatal Intensive Care Unit for the emergency area. The samples were always collected after a period of 5 days from initial use for both types of humidifiers. Samples were processed using standard bacteriological techniques and microbial colonies were identified using manual and automated methods. RESULTS: High rates of microbial contamination were observed in samples from reusable oxygen humidifiers employed in medical (83%), surgical (77%) and emergency (50%) areas. The most relevant pathogens were Pseudomonas aeruginosa, amongst the Gram-negative bacteria, and Staphylococcus aureus, amongst the Gram-positive bacteria. Other pathogens were detected in lower percentage. The disposable oxygen humidifier samples showed no contamination. CONCLUSIONS: This research presents evidence of the high rate and type of microbial contamination of reusable humidifiers employed for oxygen therapy. These devices may thus be involved in the transmission of potential pathogens. It could be important, for the prevention of nosocomial pneumonia, to replace them with singleuse humidifiers for which the absence of microbial contamination has been confirmed.

Management of two influenza vaccination campaign in health care workers of a university hospital in the south Italy.

BACKGROUND: In Europe, flu remains one of the major public health problems. Healthcare workers (HCWs) are a category at high-risk of contracting the infection and infecting their patients; consequently, for this category, vaccination is highly recommended. Unfortuntely, coverage levels remain insufficient with rates ranging between 4 and 40. STUDY DESIGN: The purpose of our work was to evaluate the adherence of HCWs to the influenza vaccination and to carry out a combination of educational and motivational interventions in order to increase the rate of adherence to the vaccination in this workers' category. METHODS: We conducted two different influenza vaccination campaigns, 2014-2015 and 2015-2016. The study was divided in two steps. In the first, preliminary step, an anonymous questionnaire was administered to HCWs containing a set of questions in order to gain information about the number of subjects willing to undergo the vaccination and the reasons that led others toits rejection. In the second step, vaccination campaigns were carried out preparing an appropriate vaccination calendar that was communicated to all interested Units and vaccination points located in various wards. RESULTS: We found a slightly improved compliance trend, from an average of 2.3% in the previous years to 3.3% in 2014 and 7.4% in 2015. CONCLUSIONS: Despite the observed increase, the adherence remains very low. We found that the main causes of this result are the fear of adverse effects, the negligence and indolence of the same workers and a lack of risk perception of contracting the disease and transmitting it to patients. Our work stressed the importance of offering correct information and of meeting the needs of HCWs, often unable to leave their ward for the excess workload. This could be, in future years, one of the possible solutions to increase vaccination adherence.

Seroprevalence of hev antibodies in a sample of pregnant women in the city of Messina.

BACKGROUND: Hepatitis E virus (HEV) is widespread in developing countries and the disease is also increasing in the developed ones. This infection in pregnancy can cause spontaneous abortion and neonatal death in 56% of newborns. STUDY DESIGN: The study was conducted on a sample of 352 pregnant women, 326 Italian and 26 foreign, in order to confirm the presence of HEV in our territory, to analyze wrong habits of the population and to suggest preventive actions against the risk to contract the infection during pregnancy. METHODS: We asked all women under study to fill an anonymous questionnaire immediately before taking a venous blood samples to determine the presence of anti-HEV antibodies. The questionnaire contained a set of questions to gain information about lifestyles and risk factors to contract HEV. RESULTS: The questionnaire revealed that a portion of the tested women have risk behaviours, as consumption of raw or undercooked food, eating unwashed food and traveling to endemic areas. The percentage of women positive for HEV antibodies was 3.4%, in agreement with national data; all the women were Italian. CONCLUSIONS: This study confirms the circulation of HEV in the city of Messina. For this reason, it is highly recommended to disseminate hygienic and appropriate behaviours and feeding habits in order to prevent the risk to contract the infection.

Response to anti-HBV vaccine and 10-year follow-up of antibody levels in healthcare workers.

BACKGROUND: Despite improvements in public health and antiviral treatments, vaccination is still the most effective means of prevention of hepatitis B virus (HBV) infection. However, little is known about the duration of protection given by the anti-HBV vaccine. Healthcare workers represent a category at risk not only of contracting infection but also of being a source of contagion to patients. OBJECTIVES: To assess individual responses to the anti-HBV vaccine and duration of protection 10 years after its administration in a cohort of healthcare workers employed by the University Hospital 'G. Martino' in Messina, Italy. METHODS: One hundred and seventy medical staff who had been vaccinated following an incident carrying risk of HBV infection were included in this study. The group was followed over a 10-year period, and HBV antibody levels were assessed using an automated microparticle enzyme immunoassay. RESULTS: Protective antibody levels (≥10 mIU/ml) were found in 65% of subjects who had completed the full vaccine schedule (three doses) and in 35% of subjects who had only received one or two doses of anti-HBV vaccine. Moreover, 10 years after vaccination, HBV antibody levels were inversely related to age at vaccination (P < 0.001). No differences were found between males and females. CONCLUSIONS: This study, in line with the literature, shows the importance of completing the full vaccine schedule (three doses). Moreover, in order to have an effective and durable antibody response and avoid the risk of contracting HBV after an injury at work, it is important to recommend anti-HBV vaccination at a young age, ideally during childhood in accordance with the national vaccination policy.

Surveillance of microbiological contamination and correct use of protective lead garments.

BACKGROUND: Healthcare associated infections are an important threat of Public Health. Several studies investigated the possible role played by the hospital environment in the transmission of nosocomial pathogens. In addition to the "classic" nosocomial surfaces, some researches focused their attention on "alternative" surfaces. Little is known about the protective lead garments used in operating rooms. STUDY DESIGN: This study was conducted in three phases to investigate the microbiological contamination and the normal use of these garments. In the first step, we administered a questionnaire to know the frequency and the type of sanitation. Then, in the second step, we conducted the microbiological samplings and, finally, in the third step, we carried out a surveillance on the use of these garments during the surgical procedures. METHODS: In the first step, we administered the questionnaire through direct interview. For microbiological sampling we used sterile swabs, the normal growth media and the API Identification System (bioMérieux). RESULTS: The study showed that the garments are sanitized only in 66.7% of the cases with a non-defined frequency. Moreover, a bacterial contamination was found on 88 garments with a positivity of 80.7% and the units with the higher rate of contamination were Urology, Orthopedics, Neuroradiology and Intensive Cardiac Care. Finally, 100% of the surgical team members wore sterile disposable shirts above the protective lead garments while this was never true for the rest of the nursing and anaesthesia team. CONCLUSIONS: To prevent the contamination of these garments, it is important to develop appropriate sanitation procedures and to store them in special cabinets also subjected to sanitation. Finally, it is necessary to focus on the correct use of the protective lead garments.

Determination of ultra-trace Sb(III) in seawater by stripping chronopotentiometry (SCP) with a mercury film electrode in the presence of copper.

This work reports the determination of ultra-trace of Sb(III) in seawater by using a stripping chronopotentiometric (SCP) method with a mercury film electrode. A sensitivity and detection limit of 360 ms L microg(-1) and 8 ng L(-1) (70 pM), respectively, were accomplished for a 15-min electrolysis time. Compared to the only two chronopotentiometric methods reported for Sb(III) determination in seawater, our method is more sensitive and does not need to use a medium exchange procedure before the stripping step. Moreover, the use of a double electrolysis potential (-450 mV and -250 mV) allows the analysis of Sb(III) independently from the Cu level in the sample. The method was successfully used to study the behaviour of dissolved Sb(III) in the Penzé estuary, NW France.

Selective stimulation of pig radial nerve: comparison of 12-polar and 18-polar cuff electrodes.

Aiming at the development of an implantable neuroprosthesis for restoration of hand function in tetraplegic patients (C5/C6), we examined and compared the stimulation performance of two different neural electrode designs. Our studies on the radial nerve of adult pigs proved the feasibility of selective control of different forearm muscles by using only one multichannel nerve cuff electrode. The results gained by applying a 12-polar cuff electrode design were poor, while the potential of an 18-polar design was very encouraging.

Structural and functional properties of hemocyanin from Cyanagraea praedator, a deep-sea hydrothermal vent crab.

Cyanagraea praedator (Crustacea: Decapoda: Brachyura) is an endemic species of the East Pacific Rise hydrothermal vents, living in the upper part of black smoker chimneys. Because we were seeking species that have made respiratory adaptations to the hydrothermal environment, we looked at Cyanograea hemocyanin (Hc) and determined its quaternary structure and the oxygen-binding properties in relation to temperature, pH, and lactate. C. praedator Hc is composed of dodecamers and hexamers, with dodecamers formed by the perpendicular association of two hexamers. The composition of these polymers was determined by electrophoresis and, for the first time, by electrospray mass spectrometry. Dodecamers and hexamers are composed of six subunits common to the two forms, with molecular mass ranging from 75,008 Da to 75,534 Da. In addition, we found two dodecamer-specific subunits, at 75,419 Da and 75,629 Da. The native hemocyanin possesses a high oxygen affinity (P(50) varies between 4 and 10 Torr at pH 7.5, 15 degrees C) and a large Bohr coefficient (Delta log P(50)/DeltapH approximately -1.8). Oxygen affinity is not affected by lactate or, surprisingly, temperature between 5 degrees C and 35 degrees C (DeltaH = 1.16 kJ/mol(1) 5-35 degrees C). Dialysis of native hemolymph elicited a significant increase in Hc-O(2) affinity (DeltaP(50) = 2.5 Torr at pH 7.5), an effect opposite the usual trend observed for crustacean hemocyanins. In this article these functional properties are interpreted in relation to characteristics of the environment.

Effect of initial joint position on nerve-cuff recordings of muscle afferents in rabbits.

The objective was to characterize nerve-cuff recordings of muscle afferents to joint rotation over a large part of the physiological joint range. This information is needed to develop control strategies for functional electrical stimulation (FES) systems using muscle afferent signals for sensory feedback. Five acute rabbit experiments were performed. Tripolar cuff electrodes were implanted around the tibial and peroneal divisions of the sciatic nerve in the rabbit's left leg. The electroneurograms (ENG) were recorded during passive ankle rotation, using a ramp-and-hold profile starting at seven different joint positions (excursion = 5 degrees, velocity = 10 degrees/s, initial positions 60 degrees, 70 degrees, 80 degrees, 90 degrees, 100%, 110 , and 120 ). The amplitude of the afferent activity was dependent on the initial joint position. The steady-state sensitivity of both nerve responses increased with increasing joint flexion, whereas the dynamic sensitivity increased initially but then decreased. The results indicate that recordings of the muscle afferents may provide reliable information over only a part of the physiological joint range. Despite this limitation, muscle afferent activity may be useful for motion feedback if the movement to be controlled is within a narrow joint range such as postural sway.

Neuro-fuzzy extraction of angular information from muscle afferents for ankle control during standing in paraplegic subjects: an animal model.

This paper is part of a project whose aim is the implementation of closed-loop control of ankle angular position during functional electrical stimulation (FES) assisted standing in paraplegic subjects using natural sensory information. In this paper, a neural fuzzy (NF) model is implemented to extract angular position information from the electroneurographic signals recorded from muscle afferents using cuff electrodes in an animal model. The NF model, named dynamic nonsingleton fuzzy logic system is a Mamdani-like fuzzy system, implemented in the framework of recurrent neural networks. The fuzzification procedure implemented was the nonsingleton technique which has been shown in previous works to be able to take into account the uncertainty in the data. The proposed algorithm was tested in different situations and was able to predict reasonably well the ankle angular trajectories especially for small excursions (as during standing) and when the stimulation sites are far from the registration sites. This suggests it may be possible to use activity from muscle afferents recorded with cuff electrodes for FES closed-loop control of ankle position during quite standing.

Nerve cuff recordings of muscle afferent activity from tibial and peroneal nerves in rabbit during passive ankle motion.

Activity from muscle afferents regarding ankle kinesthesia was recorded using cuff electrodes in a rabbit preparation in which tactile input from the foot was eliminated. The purpose was to determine if such activity can provide information useful in controlling functional electrical stimulation (FES) systems that restore mobility in spinal injured man. The rabbit's ankle was passively flexed and extended while the activity of the tibial and peroneal nerves was recorded. Responses to trapezoidal stimulus profiles were investigated for excursions from 10 degrees to 60 degrees using velocities from 5 degrees/s to 30 degrees/s and different initial ankle positions. The recorded signals mainly reflect activity from primary and secondary muscle afferents. Dorsiflexion stretched the ankle extensors and produced velocity dependent activity in the tibial nerve, and this diminished to a tonic level during the stimulus plateau. The peroneal nerve was silent during dorsiflexion, but was activated by stretch of the peroneal muscles during ankle extension. The responses of the two nerves behaved in a reciprocal manner, but exhibited considerable hysteresis, since motion that relaxed the stretch to the driving muscle produced an immediate cessation of the prior stretch induced activity. A noted difference between the tibial and peroneal nerve responses is that the range of joint position change that activated the flexor afferents was greater then for the extensor afferents. Ankle rotation at higher velocities increased the dynamic stretch evoked responses during the stimulus ramp but showed no effect on the tonic activity during the stimulus plateau. Prestretching the muscles by altering the initial position increased the response to the ramp movement, however, for the peroneal nerve, when the prestretch brought the flexor muscles near to their maximal lengths, the response to additional stretch provided by the ramp movement was diminished. The results indicate that the whole nerve recorded muscle afferent activity may be useful for control of FES assisted standing, because it can indicate the direction of rotation of the passively moved ankle joint, along with coarse information regarding the rate of movement and static joint position.

Development and evaluation of a two-dimensional electrocutaneous cognitive feedback system for use in paraplegic standing.

Fatigue of electrically activated paralysed muscles is a major factor limiting the duration of functional electrical stimulation (FES) supported paraplegic standing. Fatigue can be significantly delayed by changing the posture. Since paralysed individuals are deprived of proprio- and exteroception from the lower limbs they are not aware of the posture and loading of their paralysed legs. If suitable cognitive feedback (CF) information about posture in the sagittal and frontal planes is provided, they might be able to successfully exercise posture switching. A two-dimensional electrocutaneous CF system was developed. Relative limb loading and the location of the weighted centre of pressure were selected as informational variables. Discrete encoding schemes in the form of spatial and frequency codes were employed and the informational signals were divided into three sub-regions. The ability to correctly interpret the CF was investigated using one- and two-dimension tracking tests in three paralysed subjects, each of whom were studied over five consecutive days. All three subjects were able to use the CF in one-dimension tests. Two subjects could do the same also in two-dimension tests. The encoding scheme which was developed to communicate the selected biomechanical variables proved to be easily understood and thus appropriate for use in paraplegic standing.

Effect of intertrial delay on whole nerve cuff recordings of muscle afferents in rabbits.

Objective. The effect of the stationary period on the muscle afferent responsiveness to passive stretch was studied to determine if muscle afferent activity might be suitable as feedback in motor-neural prostheses control. Methods. Muscle afferent activity was recorded using nerve cuff electrodes applied individually to the tibial and peroneal components of the sciatic nerve in five rabbit preparations. The ankle joint was rotated using a servomotor. The delay between trapezoidal movements was varied (excursion = 30°, velocity = 20°/s) and the duration was increased stepwise in successive trials(2 s, 5 s, 10 s, 20 s, 30 s, and 180 s). Results. An increase in amplitude of the afferent activity with increasing intertrial delay was observed. The afferent responses following a 2-s delay were subtracted from the responses following each of the remaining intervals (5 s-2 s, 10 s-2 s, 20 s-2 s, 30 s-2 s and 180 s-2 s) and were then compared. During the ramp phase a statistically significant difference was found in 85% and 76% of the cases for the tibial and peroneal nerve responses. Significant differences were below 21% for both nerves during four other phases examined. Conclusions. It is suggested that the enhancement in afferent responses caused by the increased intertrial delay may be explained by the change in the mechanical properties of the intrafusal and extrafusal muscle fibers. The consequences of this, when applying muscle afferent activity in motor-neuro prostheses, are discussed.

Strategies for providing upper extremity amputees with tactile and hand position feedback--moving closer to the bionic arm.

A continuing challenge for prostheses developers is to replace the sensory function of the hand. This includes tactile sensitivity such as finger contact, grip force, object slippage, surface texture and temperature, as well as proprioceptive sense. One approach is sensory substitution whereby an intact sensory system such as vision, hearing or cutaneous sensation elsewhere on the body is used as an input channel for information related to the prosthesis. A second technique involves using electrical stimulation to deliver sensor derived information directly to the peripheral afferent nerves within the residual limb. Stimulation of the relevant afferent nerves can ultimately come closest to restoring the original sensory perceptions of the hand, and to this end, researchers have already demonstrated some degree of functionality of the transected sensory nerves in studies with amputee subjects. This paper provides an overview of different types of nerve interface components and the advantages and disadvantages of employing each of them in sensory feedback systems. Issues of sensory perception, neurophysiology and anatomy relevant to hand sensation and function are discussed with respect to the selection of the different types of nerve interfaces. The goal of this paper is to outline what can be accomplished for implementing sensation into artificial arms in the near term by applying what is present or presently attainable technology.

Restoration of lateral hand grasp using natural sensors.

A closed-loop control system for controlling the key grip of a C6 tetraplegic patient was developed. Natural sensors served as the source of the feedback signal. The neural signals from cutaneous receptors were picked up by an implanted cuff electrode placed around the radial branch of the median nerve innervating the lateral part of the index finger. Mechanical stress applied to the skin, like pressure and slips, resulted in an increase in amplitude of the recorded neural signal. The goal of the study was to determine whether the recorded neural signals were able to indicate the slip of an object during lateral grasp and whether the slip could be stopped by increasing the grasp force through functional electrical stimulation of the thumb adductor and flexor.

Perspectives on the role of afferent signals in control of motor neuroprostheses.

K.O. Johnson reviews the architecture and low level neural mechanisms by which the external environment is transduced and encoded into the neural system, summarizing work that correlates neurophysiological and psychophysical testing with isolation of sensory components. The slowly adapting Type I afferent system is responsible for form and texture perception; the rapidly adapting afferent system is responsible for motion perception; and the Pacinian corpuscle system is responsible for vibratory sensation. R.R. Riso reviews the current level of understanding of the major factors to be considered in the design of a functional neuromuscular stimulation (FNS) grasp controller that uses cutaneous sensory feedback to detect slip. The elegant natural control scheme that matches the ratio of grip and lift forces to frictional conditions provides a model for implementing a slip-based control algorithm. D. Popovic discusses the possible use of recordings from more proximal peripheral nerves to determine needed information for synthesis of locomotion. The discussion is illustrated with an animal model where rule-based closed-loop control is used for the ankle joint during treadmill locomotion. Neural signals from the tibial and superficial peroneal nerves were employed to substitute for missing afferent input from cutaneous and proprioceptive sensors. The feasibility of more invasive intraneural electrodes for distinguishing sensory from motor information in mixed nerves is considered. M. Koris raises surgical and functional issues relevant to developing clinical FNS systems. C. Van Doren suggests alternative neurophysiological and engineering approaches.

Efficacy of two temephos formulations against Chironomus salinarius (Diptera: Chironomidae) in the saltwater lagoon of Venice, Italy.

Two formulations of the organophosphorus insecticide, temephos (Abathion Granulare, 1% AI granular and Tambro Compresse, 2% AI tablet) were evaluated against Chironomus salinarius midge larvae in 50 x 50 m experimental plots in the saltwater lagoon of Venice, Italy. Each formulation was applied at 0.2 and 0.4 kg AI/ha. Abathion Granulare produced 56 to 73% larval reduction at 0.2 kg AI/ha and 69 to 83% reduction at 0.4 kg AI/ha during 3 wk after treatment. Abathion Granulare lost effectiveness at 4 wk after application at both rates. Posttreatment larval reductions resulting from Tambro Compresse applications ranged from 77 to 86% for 3 wk, and 82 to 92% for 4 wk at rates of 0.2 and 0.4 kg AI/ha, respectively. The tablet formulation (Tambro Compresse) gave better control of C. salinarius (magnitude and duration) than the granular formulation (Abathion Granulare) in these evaluations.

Somatosensory control of precision grip during unpredictable pulling loads. I. Changes in load force amplitude.

In manipulating 'passive' objects, for which the physical properties are stable and therefore predictable, information essential for the adaptation of the motor output to the properties of the current object is principally based on 'anticipatory parameter control' using sensorimotor memories, i.e., an internal representation of the object's properties based on previous manipulative experiences. Somatosensory afferent signals only intervene intermittently according to an 'event driven' control policy. The present study is the first in a series concerning the control of precision grip when manipulating 'active' objects that exert unpredictable forces which cannot be adequately represented in a sensorimotor memory. Consequently, the manipulation may be more reliant on a moment-to-moment sensory control. Subjects who were prevented from seeing the hand used the precision grip to restrain a manipulandum with two parallel grip surfaces attached to a force motor which produced distally directed (pulling) loads tangential to the finger tips. The trapezoidal load profiles consisted of a loading phase (4 N/s), plateau phase and an unloading phase (4 N/s) returning the load force to zero. Three force amplitudes were delivered in an unpredictable sequence; 1 N, 2 N and 4 N. In addition, trials with higher load rate (32 N/s) at a low amplitude (0.7 N), were superimposed on various background loads. The movement of the manipulandum, the load forces and grip forces (normal to the grip surfaces) were recorded at each finger. The grip force automatically changed with the load force during the loading and unloading phases. However, the grip responses were initiated after a brief delay. The response to the loading phase was characterized by an initial fast force increase termed the 'catch-up' response, which apparently compensated for the response delay--the grip force adequately matched the current load demands by the end of the catch-up response. In ramps with longer lasting loading phases (amplitude greater than or equal to 2 N) the catch-up response was followed by a 'tracking' response, during which the grip force increased in parallel with load force and maintained an approximately constant force ratio that prevented frictional slips. The grip force during the hold phase was linearly related to the load force, with an intercept close to the grip force used prior to the loading. Likewise, the grip force responses evoked by the fast loadings superimposed on existing loads followed the same linear relationship.(ABSTRACT TRUNCATED AT 400 WORDS)