Force controlled and teleoperated endoscopic grasper for minimally invasive surgery--experimental performance evaluation

Minimally invasive surgery generates new user interfaces which create visual and haptic distortion when compared to traditional surgery. In order to regain the tactile and kinesthetic information that is lost, a computerized force feedback endoscopic surgical grasper (FREG) was developed with computer control and a haptic user interface. The system uses standard unmodified grasper shafts and tips. The FREG can control grasping forces either by surgeon teleoperation control, or under software control. The FREG performance was evaluated using an automated palpation function (programmed series of compressions) in which the grasper measures mechanical properties of the grasped materials. The material parameters obtained from measurements showed the ability of the FREG to discriminate between different types of normal soft tissues (small bowel, lung, spleen, liver, colon, and stomach) and different kinds of artificial soft tissue replication materials (latex/silicone) for simulation purposes. In addition, subjective tests of ranking stiffness of silicone materials using the FREG teleoperation mode showed significant improvement in the performance compared to the standard endoscopic grasper. Moreover, the FREG performance was closer to the performance of the human hand than the standard endoscopic grasper. The FREG as a tool incorporating the force feedback teleoperation technology may provide the basis for application in telesurgery, clinical endoscopic surgery, surgical training, and research.

Performances of hill-type and neural network muscle models-toward a myosignal-based exoskeleton

Muscle models are the essential components of any musculoskeletal simulation. In addition, muscle models which are incorporated in neural-based prosthetic and orthotic devices may significantly improve their performance. The aim of the study was to compare the performances of two types of muscle models in terms of predicting the moments developed at the human elbow joint complex based on joint kinematics and neuromuscular activity. The performance evaluation of the muscle models was required to implement them in a powered myosignal-driven exoskeleton (orthotic device). The experimental setup included a passive exoskeleton capable of measuring the joint kinematics and dynamics in addition to the muscle myosignal activity (EMG). Two types of models were developed and analyzed: (i) a Hill-based model and (ii) a neural network. The task, which was selected for evaluating the muscle models performance, was the flexion-extension movement of the forearm with a hand-held weight. For this task the muscle model inputs were the normalized neural activation levels of the four main flexor-extensor muscles of the elbow joint, and the elbow joint angle and angular velocity. Using this inputs, the muscle model predicted the moment applied on the elbow joint during the movement. Results indicated a good performance of the Hill model, although the neural network predictions appeared to be superior. Relative advantages and shortcomings of both approaches were presented and discussed.

Utility of intracardiac echocardiography (ICE) in electrophysiology: ICEing the CAKE (catheter ablation knowledge enhancement)

PURPOSE

Previous studies have demonstrated the utility of intracardiac echocardiography (ICE) during electrophysiologic procedures including radiofrequency catheter ablation. The purpose of this study was to analyze the initial learning experience with ICE during invasive electrophysiologic procedures.

METHODS

During a 1-month ICE trial, patients scheduled for radiofrequency catheter ablation underwent concurrent imaging using a 9 French, 9 MHz catheter in the right atrium proximal to important endocardial structures and diagnostic/ablation catheters. The procedure length, fluoroscopy and ICE times were systematically recorded during each procedure. In addition, the images were analyzed and recorded and their utility was evaluated after each case. A case control analysis was also performed.

RESULTS

Seven patients underwent ICE (as part of an ICE trial period) during their electrophysiology study between July 21 and August 13, 1998. This study demonstrated the utility of ICE in identifying radiofrequency catheter tip stability and intracardiac and endocardial structures, including the crista terminalis, coronary sinus, and foramen ovale.

CONCLUSION

ICE contributes to the electrophysiology arsenal for both diagnostic and therapeutic procedures. In particular, this technique demonstrated a decrease in fluoroscopy time as compared to a case control population. This technique limits radiation to the patient and operator. In addition, endocardial structures, which may be pivotal in diagnosing and treating cardiac arrhythmias, were easily identified. Radiofrequency catheter stability can also be assessed with this technique.

Force-feedback grasper helps restore sense of touch in minimally invasive surgery

The age of minimally invasive surgery has brought forth astounding changes in the health care field. Less pain and quicker patient recovery have been demonstrated with several types of operations that were once performed by an open technique. With these changes have come reports of complications. The decreased sense of touch is just one of several limitations inherent to current techniques of minimally invasive surgery that limit detection of subtle or unapparent lesions on palpation, such as common duct stones and liver lesions. The purpose of this study is to demonstrate the ability of a force-feedback-equipped grasper to restore some of the sense of touch that is lost in minimally invasive surgery. To demonstrate this ability, we created six silicone phantoms of identical dimensions but graded compliance, and asked 10 subjects to place them in increasing/decreasing order of compliance. They used three tools (their dominant gloved hand, a standard laparoscopic Babcock grasper, and our force-feedback device fitted with the identical Babcock grasper) to rate the compliance of the samples in a blinded fashion. These conditions thus approximated the conditions of open surgery, minimally invasive surgery, and minimally invasive surgery fitted with a force-sensing device, in terms of palpating tissues. Five surgeons skilled in minimally invasive surgery and five nonsurgeons participated in the study. The results indicate that the force-feedback device is significantly (P <0.05) better than a standard Babcock grasper at rating tissue compliance, but was not as successful as a gloved hand (mean of squared errors = 1.06, 3. 15, and 0.25, respectively). There was no significant difference between surgeons and nonsurgeons in rating compliance. We conclude that this force-feedback instrument is able to partially restore the sense of touch in minimally invasive surgery. This restored ability may thus potentially result in more efficient operations with improved diagnostic capabilities and fewer complications during minimally invasive surgery.

Design of conditionally active STATs: insights into STAT activation and gene regulatory function

The STAT (signal transducer and activator of transcription) signaling pathway is activated by a large number of cytokines and growth factors. We sought to design a conditionally active STAT that could not only provide insight into basic questions about STAT function but also serve as a powerful tool to determine the precise biological role of STATs. To this end, we have developed a conditionally active STAT by fusing STATs with the ligand-binding domain of the estrogen receptor (ER). We have demonstrated that the resulting STAT-ER chimeras are estrogen-inducible transcription factors that retain the functional and biochemical characteristics of the cognate wild-type STATs. In addition, these tools have allowed us to evaluate separately the contribution of tyrosine phosphorylation and dimerization to STAT function. We have for the first time provided experimental data supporting the model that the only apparent role of STAT tyrosine phosphorylation is to drive dimerization, as dimerization alone is sufficient to unmask a latent STAT nuclear localization sequence and induce nuclear translocation, sequence-specific DNA binding, and transcriptional activity.

Three-dimensional joint transform correlator

The three-dimensional (3-D) joint transform correlator is demonstrated with realistic targets. Three-dimensional objects observed by multiple cameras are correlated with a 3-D reference object. The number of cameras and their directions of observation are particularly considered.

Localization of postsynaptic density-93 to dendritic microtubules and interaction with microtubule-associated protein 1A

Postsynaptic density-93 (PSD-93)/Chapsyn-110 is a member of the membrane-associated guanylate kinase (MAGUK) family of PDZ domain-containing proteins. MAGUKs are widely expressed in the brain and are critical elements of the cytoskeleton and of certain synapses. In the ultrastructural studies that are described here, PSD-93 localizes to both postsynaptic densities and dendritic microtubules of cerebellar Purkinje neurons. The microtubule localization is paralleled by a high-affinity in vivo interaction of PSD-93 via its guanylate kinase (GK) domain with microtubule-associated protein 1A (MAP1A). GK domain truncations that mimic genetically identified mutations of a Drosophila MAGUK, discs-large, disrupt the GK/MAP-1A interaction. Additional biochemical experiments demonstrate that intact MAGUKs do not bind to MAP1A as effectively as do isolated GK domains. This appears to be attributable to an intramolecular inhibition of the GK domain by the PDZs, because GK binding activity of full-length MAGUKs is partially restored by a variety of PDZ ligands, including the C termini of NMDA receptor 2B, adenomatous polyposis coli (APC), and CRIPT. Beyond demonstrating a novel cytoskeletal link for PSD-93, these experiments support a model in which intramolecular interactions between the multiple domains of MAGUKs regulate intermolecular associations and thereby may play a role in the proper targeting and function of MAGUK proteins.

Cognitive and motor slowing in Alzheimer's disease and geriatric depression

While response slowing on psychological tasks is a symptom of both depression and Alzheimer's disease (AD), the underlying mechanisms may be quite different: a slowing of cognitive processing in AD and a motor retardation in depression. This hypothesis was tested by examining the rate at which participants performed a simple cognitive operation: subvocal pronunciation. Participants were shown words of between one and three syllables and were asked to decide whether each word ended in a particular sound. This task required participants to transform the written word into its phonological representation, an operation thought to involve subvocal pronunciation. Decision time rose linearly with the number of syllables in all three subject groups. The linear function of the AD patients had a significantly greater slope, indicating a slower rate of subvocal pronunciation, whereas the slope was the same for the normal old and depressed. Both the depressed and AD patients had a higher intercept than the normal old, suggesting a sensorimotor slowing. After treatment, the intercept of the linear function for depressed patients fell, but there was no change in the slope. Thus, this study suggests that AD produces a slowing in both cognitive and motor processes, whereas depression results solely in a motor retardation.

A small, nonpeptidyl mimic of granulocyte-colony-stimulating factor [see commetns]

A nonpeptidyl small molecule SB 247464, capable of activating granulocyte-colony-stimulating factor (G-CSF) signal transduction pathways, was identified in a high-throughput assay in cultured cells. Like G-CSF, SB 247464 induced tyrosine phosphorylation of multiple signaling proteins and stimulated primary murine bone marrow cells to form granulocytic colonies in vitro. It also elevated peripheral blood neutrophil counts in mice. The extracellular domain of the murine G-CSF receptor was required for the activity of SB 247464, suggesting that the compound acts by oligomerizing receptor chains. The results indicate that a small molecule can activate a receptor that normally binds a relatively large protein ligand.

Computerized endoscopic surgical grasper

We report a computerized endoscopic surgical grasper with computer control and a force feedback (haptic) user interface. The system uses standard unmodified grasper shafts and tips. The device can control grasping forces either by direct surgeon control, via teleoperation, or under software control. In this paper, we test an automated palpation function in which the grasper measures mechanical properties of the grasped tissue by applying a programmed series of squeezes. Experimental results show the ability to discriminate between the normal tissues of small bowel, lung, spleen, liver, colon, and stomach. We anticipate applications in telesurgery, clinical endoscopic surgery, surgical training, and research.

Association of plasma homovanillic acid with behavioral symptoms in patients diagnosed with dementia: a preliminary report

Neuroleptic treatment of psychotic symptoms or agitated behavior in elderly patients diagnosed with dementia is associated with reduced efficacy and increased rates of neuroleptic-induced parkinsonism in comparison to younger patients with schizophrenia. We report the first study to examine the relationship between an in vivo measure of dopaminergic function, plasma homovanillic acid (pHVA), and ratings of psychosis, agitation, and parkinsonism before and after neuroleptic treatment in dementia patients. Pretreatment pHVA was significantly correlated with parkinsonian rigidity, with a trend observed with agitation and hostility. Though mean pHVA did not change during perphenazine treatment, intraindividual change in pHVA at day 15 was correlated with improvement in hostility, with a similar trend for improvement in agitation. These preliminary findings are consistent with reports associating dopaminergic function with agitated, but not psychotic, symptoms in patients diagnosed with dementia, and with a reduced responsivity of dopaminergic systems to neuroleptic treatment in these patients.

Drug migration from the adhesive matrix to the polymer film laminate facestock in a transdermal nitroglycerin system

The apparent loss of nitroglycerin in a prototype transdermal nitroglycerin system was investigated by attenuated total reflectance infrared (ATR-IR) microspectroscopy and high performance liquid chromatography (HPLC). Several transdermal nitroglycerin lots placed under controlled storage conditions exhibited loss of drug potency (up to 10%) along with the appearance of a defect in the polymer film laminate facestock. A significant loss of nitroglycerin from the transdermal drug/adhesive matrix may reduce the bioavailabilty of nitroglycerin to the patient. ATR-IR analysis confirmed that nitroglycerin migrated from the drug/adhesive matrix to the facestock polyester layer under storage conditions and that nitroglycerin was retained in the facestock polyester layer. An alternate sample extraction solution successfully removed the nitroglycerin from both the adhesive matrix and facestock polyester layer with nearly 100% labeled strength recovered. The relationship between the migration of nitroglycerin into the facestock polyester layer and the appearance of the defect in the facestock aluminum layer is discussed and a nitroglycerin-aluminum metal reaction mechanism is proposed.

Spectroscopic identification of an amorphous-to-crystalline drug transition in a solid dispersion SCH 48461 capsule formulation

Changes in the dissolution of a solid dispersion capsule formulation composed of amorphous SCH 48461 in a polyethylene glycol 8000 matrix were investigated. SCH 48461 [(3R,4S)-1,4-bis(4-methoxyphenyl)-3-(3-phenylpropyl)-2-azetidinone] is a potent cholesterol absorption inhibitor with low water solubility and low melting point. Several capsule lots placed under controlled storage conditions exhibited a slowing of dissolution as a function of time with large inter-lot and intra-lot dissolution variations. Capsule contents were analyzed by attenuated total reflectance infrared (ATR-IR) microspectroscopy and solid-state cross-polarization, magic angle spinning (CPMAS) 13C-nuclear magnetic resonance (NMR) spectrometry. ATR-IR microspectroscopic analysis showed large IR spectral differences between the lots including the presence of a crystalline drug fraction in lots which exhibited incomplete dissolution. Solid-state CPMAS 13C-NMR analysis confirmed the presence of a crystalline drug fraction in the problematic capsule lots. Both ATR-IR and CPMAS 13C-NMR spectral results produced a rank ordering of the crystalline drug fraction present in the capsule lots that correspond to the dissolution results.

Effect of sertraline on plasma nortriptyline levels in depressed elderly

BACKGROUND

Several serotonin selective reuptake inhibitors have been reported to be inhibitors of the cytochrome P450 2D6 (CYP2D6). Thus, they may increase the plasma level of secondary amine tricyclic antidepressants, which are predominantly metabolized through this enzyme. Except for a few case reports, no clinical data document the degree of this drug-drug interaction in elderly depressed patients.

METHOD

We systematically examined this interaction by determining the change in plasma nortriptyline levels in 14 elderly depressed patients in whom sertraline was added to nortriptyline.

RESULTS

After addition of 50 mg/day of sertraline, the median increase in plasma nortriptyline level over baseline was 2% (range, -26% to 117%; p = .30). In 2 patients (14%), there was an increase of 50% or more. For patients taking higher sertraline doses (N = 7; 100 or 150 mg/day), the median increase in plasma nortriptyline level over baseline was 40% (range, -12% to 239%; p = .08).

CONCLUSION

Overall, a modest effect of sertraline was observed on nortriptyline metabolism in these elderly depressed patients. This is consistent with prior reports of a weak inhibition of CYP2D6 by sertraline in vitro and in young healthy volunteers. However, some patients showed a change in plasma nortriptyline level that would be considered clinically significant. Thus, careful monitoring of plasma nortriptyline levels is recommended in all patients treated with a combination of nortriptyline and sertraline.

The effects of perphenazine on the concentration of nortriptyline and its hydroxymetabolites in older patients

Twenty-five older patients who presented with psychotic depression were treated with a combination of nortriptyline and perphenazine. Plasma levels of nortriptyline, E-, and Z-10-OH nortriptyline (E- and Z-10-OH-NT) were measured before and after addition of perphenazine. The mean (+/-SD) initial nortriptyline dose was 59 +/- 24 mg/day, whereas the mean final nortriptyline and perphenazine doses were 56 +/- 24 and 19 +/- 13 mg/day, respectively. The mean plasma level to dose quotient for perphenazine (0.45 +/- 0.34 nM/mg/day) was comparable to the mean quotient reported previously in older psychotic patients treated with perphenazine alone. After addition of perphenazine, the median quotient of nortriptyline plasma level to nortriptyline dose (L/D) increased significantly (from 6.1 to 8.6). This change was inversely correlated with baseline nortriptyline L/D. The median ratio of E-10-OH-NT to nortriptyline plasma level decreased significantly (from 1.6 to 1.3), whereas the median ratio of Z-10-OH-NT to nortriptyline plasma level did not change significantly. These results are consistent with the known inhibition by perphenazine of the cytochrome P450 2D6 (sparteine/debrisoquine hydroxylase), the major enzyme involved in the oxidative metabolism of nortriptyline, mostly through the formation of E-10-OH-NT. This complex alteration in the metabolism of nortriptyline induced by perphenazine emphasizes the relevance of measuring plasma levels not only of nortriptyline but also of its hydroxymetabolites in older patients who are more likely to be sensitive to their differing cardiovascular, anticholinergic, and cognitive effects.

A brain imaging (single photon emission computerized tomography) study of semantic and affective processing in psychopaths

Psychopaths have been described as human predators who use charm, intimidation, and violence to control others and to satisfy their own needs. Underlying their propensity to violate social norms and expectations is a profound lack of empathy, guilt, or remorse, affective processes that have long resisted scientific investigation. Using brain imaging technology we found that psychopaths differed from nonpsychopaths in the pattern of relative cerebral blood flow during processing of emotional words. The results were consistent with the hypothesis that there are anomalies in the way psychopaths process semantic and affective information.

Three-dimensional optical Fourier transform and correlation

Optical implementation of a three-dimensional (3-D) Fourier transform is proposed and demonstrated. A spatial 3-D object, as seen from the paraxial zone, is transformed to the 3-D spatial frequency space. Based on the new procedure, a 3-D joint transform correlator is described that is capable of recognizing targets in the 3-D space.

Methodological issues in characterizing treatment response in demented patients with behavioral disturbances

Despite the proliferation of instruments developed to rate behavioral disturbances associated with dementia, systematic studies of how ratings on these instruments should be analyzed to measure change in disruptive behaviors or distressing symptoms (ie treatment response) are noticeably absent. Using one of these scales, we compared three methods to characterize treatment response in 52 elderly demented inpatients who participated in a standardized neuroleptic trial. While all three analyses identified a statistically significant improvement, they conveyed differently the clinical improvement experienced by the patients. Categorical outcomes communicated the clinical meaning of improvement better than changes in total score; changes in factor scores best revealed the differential impact of treatment on specific behavioral and symptomatic domains. Given the heterogeneity of the problematic behaviors and symptoms exhibited by demented patients included in treatment trials, regardless of the intervention being tested or of the instrument being used to rate behaviors, a focused approach to characterizing treatment response is needed.

Increased G-CSF responsiveness of bone marrow cells from hematopoietic cell phosphatase deficient viable motheaten mice

The mouse mutation viable motheaten (me(v)) results in defects in the expression and catalytic activity of the cytoplasmic protein tyrosine phosphatase known as hematopoietic cell phosphatase (HCP). This reduction in HCP activity leads to the aberrant regulation of several myeloid and lymphoid cell lineages, including substantial increases in numbers of granulocytes. The differentiation, proliferation, and survival of cells in this lineage are normally supported by granulocyte-colony stimulating factor (G-CSF). In this study we have determined the consequences of the loss of HCP activity in me(v)/me(v) mice on the response of bone marrow cells to G-CSF. Bone marrow from these mice exhibited substantial increases in clonogenic and proliferative responses to G-CSF. These enhanced activities of G-CSF correlated with an increase in the level of immature granulocytic, G-CSF receptor positive cells in the bone marrow. These results suggested the possibility that HCP may regulate the G-CSF receptor by a direct interaction. However, under conditions where the previously described interaction between the erythropoietin receptor and HCP was readily observed, HCP did not detectably associate with the G-CSF receptor.

Plasma levels of citalopram enantiomers and metabolites in elderly patients

Ten patients with dementia and significant behavioral disturbances (mean age of 77.2 +/- 8.2 years) received citalopram, 10 mg/day for 3 days, followed by 20 mg/day for 2 weeks. Six of the 10 patients completing 17 days of treatment had a clinically impressive response, as assessed by significant improvement in six target items on the Neurobehavioral Rating Scale. Eight patients were also analyzed by measuring the racemic and enantiomeric plasma levels of citalopram (CIT) and desmethylcitalopram (DCIT). A sensitive high-performance liquid chromatography (HPLC) assay for citalopram enantiomers and metabolites was developed using ultraviolet detection. The lower limit of detection was 10 ng/ml for each enantiomer. Steady-state plasma level ranges were 11.2 to 92.2 ng/ml for the biologically active S(+) citalopram and 12.8 to 95.7 ng/ml for the inactive R(-) enantiomer. For the S and R enantiomers of desmethylcitalopram, plasma levels ranged from 11.0 to 22.0 ng/ml and 9.2 to 22.0 ng/ml, respectively. The racemic citalopram plasma level to dose ratio of 3.50 was higher than the ratio (1.96) reported by Overo (1982) for 55 younger patients. The stereoselective metabolism of the enantiomers for citalopram and desmethylcitalopram (S(+) and R(-) enantiomers) in these older subjects differed from that reported in younger patients, suggesting possible age-associated changes in CYP2C19 activities. We hypothesize that quantification of S(+) citalopram will permit a more accurate examination of dose/response relationships. This measure seems to be especially important for older subjects, given the wide ranges and higher concentrations evident from our preliminary results.