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At least 451 records · Page 25Linked to original sources

PubMed2005

Spherical mechanism analysis of a surgical robot for minimally invasive surgery -- analytical and experimental approaches.

Recent advances in technology have led to the fusion of MIS techniques and robot devices. However, current systems are large and cumbersome. Optimizing the surgical robot mechanism will eventually lead to its integration into the operating room (OR) of the future becoming the extended presence of the surgeon and nurses in a room occupied by the patient alone. By optimizing a spherical mechanism using data collected in-vivo during MIS procedures, this study is focused on a bottom-up approach to developing a new class of surgical robotic arms while maximizing their performance and minimizing their size. The spherical mechanism is a rotational manipulator with all axes intersecting at the center of the sphere. Locating the rotation center of the mechanism at the MIS port makes this class of mechanism a suitable candidate for the first two links of a surgical robot for MIS. The required dexterous workspace (DWS) is defined as the region in which 95% of the tool motions are contained based on in-vivo measurements. The extended dexterous workspace (EDWS) is defined as the entire abdominal cavity reachable by a MIS instruments. The DWS is defined by a right circular cone with a vertex angle of 60 degrees and the EDWS is defined by a cone with an elliptical cross section created by two orthogonal vertex angles of 60 degrees and 90 degrees. A compound function based on the mechanism's isotropy and the mechanism stiffness was considered as the performance metric cost function. Optimization across both the DWS and the EDWS lead to a serial mechanism configuration with link length angles of 74 degrees and 60 degrees for a serial configuration. This mechanism configuration maximized the kinematic performance in the DWS while keeping the EDWS as its reachable workspace. Surgeons, using a mockup of two mechanisms in a MIS setup, validated these results experimentally. From these experiments the serial configuration was deemed most applicable for MIS robotic applications compared to a parallel mechanism configuration. The mechanical design of a cable actuated surgical robot was based on optimized link length angles. The system is currently being integrated into a fully operated two-arm system. Small form-factor surgical robotic arms with optimized dexterous workspaces will facilitate the integration of multiple arms while avoiding self-collision in the OR of the future.

Robotics↗

PubMed2005

[Changes of grip and pinch strength after carpal tunnel release].

OBJECTIVES: Evaluation of changes of the total grip strength, two-point pinch, three-point pinch, key-pinch and a subjective improvement of the dexterity of the hand measured by functional part of Levine questionnaire within first year after carpal tunnel release. PATIENTS AND METHODS: Thirty-nine patients with carpal tunnel syndrome (CTS) were evaluated for changes of aforementioned grips, pinches and completed the Levine questionnaire. All measurements were performed with set of digital dynamometers. Patients were assessed before the operation and at 3, 6 and finally at 12 months after surgery. In all cases carpal tunnel was released by double incision open technique. RESULTS: All grips and pinches improved significantly within first year after surgery with respect to preoperative values. Mean total grip strength increased at 3 months to 109%, at 6 months to 123% and at 12 months to 138%. Statistically significant difference was noted at 6 and 12 months. Mean value of two-point pinch was at 3 months of 117% preoperative value, at 3 months of 131% and at 12 months of 145%. Statistically significant difference was noted at 12 months. Mean value of three-point pinch was at 3 months of 114% preoperative value, at 6 months of 130% and at 12 months of 144%. Statistically significant difference was noted at 6 and 12 months. Mean value of key-pinch strength was at 3 months of 105% preoperative value, at 6 months of 117% and at 12 months of 145%. Statistically significant difference was noted at 6 and 12 months. Subjective evaluation of dexterity of the hand by functional part of Levine questionnaire revealed statistically significant improvement in all four post-operative examinations. CONCLUSION: Power of the hand improved gradually within whole first year after carpal tunnel release, however statistically significant difference was noted as late as at 6 and 12 months after surgery. In subjective opinion of patients the dexterity of the hand improves gradually during whole 12 months follow-up.

Adult↗

PubMedDate not supplied

[Computer-based rehabilitation of cognitive impairments and motor arm function of patients with hemiparesis after stroke].

OBJECTIVE: To evaluate the usefulness of the computer program made for the patients after stroke to treat their cognitive impairments and hemiparesis. RESEARCH DESIGN AND METHODS: The experimental group involved 10 patients after stroke who were obliged to train on a computer every day during their three-week stay on the rehabilitation ward. The control group involved 10 patients after stroke who did not participate in any computer training during their rehabilitation process. The first part of the computer tasks trains the attention impairments and visual-motor co-ordination problems. We modified the joystick by adding special buttons to train movements of the wrist, thumb and forefinger of the impaired hand. Computer tasks are made in the way to stimulate both the cognitive functions and hand dexterity at the same time. RESULTS: This initial research shows a statistically significant improvement of the cognitive functions and hand dexterity among patients from the experimental group. According to these results we did not observe any significant improvement in the cognitive functions among patients who did not train on a computer (control group). CONCLUSIONS: The results of this research suggest the usefulness of this computer program in training cognitive impairments and visual-motor co-ordination as well as hand dexterity among the patients after stroke.

Activities of Daily Living↗

PubMed2006

Gender differences in the attainment of motor skills on the Movement Assessment Battery for Children.

Differences in the age of attainment of motor skills between boys and girls have been established in previous studies. It has been noted that boys develop ball skills earlier than girls and that girls acquire manual dexterity before boys. The purpose of this study was to determine if the same differences could be identified in a group of typically developing seven and eight year old children using the Movement Assessment Battery for Children Test (MABC Test). In this study, a physiotherapist administered the MABC Test to 103 randomly selected children (boys-60, girls-43). The MABC Test examines children's motor skills in the areas of manual dexterity, ball skills and balance. Results were analyzed using analysis of variance (ANOVA). The ANOVA results indicated significant differences between boys' and girls' ball skill scores and manual dexterity scores.

Age Factors↗

PubMed1989

Differential effects of TGF-beta 1 on lymphohemopoiesis in long-term bone marrow cultures.

Latent transforming growth factors beta (TGF-beta) are easily detectable in embryonic and adult hematopoietic tissues and in vitro studies show that they are potent antagonists of lymphopoiesis and myelopoiesis when converted to biologically active form. To learn more about possible roles in hematopoiesis, active TGF-beta 1 was added to cultures prepared to support myeloid cells (Dexter conditions) or B lineage lymphocytes (Whitlock-Witte conditions) and studied in detail. Hematopoiesis was permanently arrested in Dexter cultures treated with 40 pmol/L (1 ng/mL) of active TGF-beta from initiation. In addition, adipogenesis was inhibited in a dose-dependent manner, and adherent layers from treated cultures were defective when recharged with fresh bone marrow cells. Ongoing neutrophil production was terminated in established cultures when addition of the factor was delayed for 8 weeks. In contrast, in experiments with Whitlock-Witte cultures, some of the flasks produced lymphocytes in the continuous presence of TGF-beta 1 (40 pmol/L). Lymphopoiesis was completely arrested by ten-fold higher concentrations, and this was most effective when added at the beginning of culture. Precursors of lymphocytes as well as the microenvironmental elements necessary for supporting their growth survived 2 weeks of cytokine treatment (400 pmol/L) in Dexter cultures. Normal outgrowth of lymphocytes occurred when the cultures were switched to Whitlock-Witte conditions. Surface marker expression on lymphocytes growing in TGF-beta resistant or previously treated cultures was not unusual. These studies demonstrate that TGF-beta is a negative regulator of hematopoiesis in long-term cultures and show that this includes effects on microenvironmental elements. At low concentrations, production of myeloid cells was preferentially affected.

Animals↗

PubMed1987

The effect of lithium on growth factor production in long-term bone marrow cultures.

We have previously reported that lithium chloride (LiCl) stimulates the production of granulocyte-macrophage colony-forming cells (GM-CFC), pluripotent stem cells (CFU-S), and differentiated granulocytes, macrophages and megakaryocytes in murine Dexter marrow cultures and that this effect appears to be mediated indirectly by a radioresistant adherent marrow cell. In this study we have established that exposure of murine Dexter cultures to LiCl (4 mEq/L) causes an increase of colony-forming cell megakaryocytes (CFU-meg) over 1 to 6 weeks of culture in both supernatant (188% to 611%) and stromal phases (123% to 246%). Moreover, we have shown that lithium treatment of either irradiated (1,100 rad) or unirradiated stromal cells increased production of activities stimulating formation of megakaryocyte, granulocyte, macrophage, and mixed lineage colonies and proliferation of the factor-dependent cell line, FDC-P1. This FDC-P1 stimulatory activity was completely blocked by an antibody to purified recombinant granulocyte-macrophage colony stimulating factor (rGM-CSF). The baseline or lithium-induced--stromal-derived bone marrow colony stimulating activity was partially blocked by the antibody to rGM-CSF and by an antibody to purified colony stimulating factor I (CSF-1); the two antibodies combined resulted in greater than 90% inhibition of the lithium-induced marrow stimulatory activity. In addition, radioimmunoassay (RIA) showed that although CSF-1 was detectable in supernatants of these cultures, exposure to lithium did not increase CSF-1 levels. These data indicate that Dexter stromal cells produce CSF-1 and GM-CSF and that lithium appears to exert its stimulatory effects on in vitro myelopoiesis by inducing production of GM-CSF.

Animals↗

PubMed1987

Stromal cell regulation of lymphoid and myeloid differentiation.

In vitro microenvironmental influences seem to be critical for both B lymphocyte and myeloid differentiation. Studies on murine Dexter cultures and Whitlock-Witte lymphocyte cultures suggest the presence of two critical stromal regulatory cells: an alkaline-phosphatase-positive epithelioid cell and a macrophage. Further data suggest that these cells are capable of producing colony stimulating factor-1, granulocyte-macrophage CSF, a myeloid synergizing activity, and probably separate B cell growth factors. Isolation of a cell line from Dexter stroma was accomplished and this line produced CSF-1, GM-CSF, a pre-B cell and myeloid synergizing activity, and an activity acting on differentiated B cells. We speculate that the Dexter and Whitlock-Witte in vitro culture systems are regulated by factors produced by the two adherent cell types. A lineage nonspecific factor capable of inducing cells into the B lineage or synergizing with interleukin-3, GM-CSF, and CSF-1 is produced, which presumably acts on early stem cells. In addition, the cell line produces GM-CSF, CSF-1, and a factor acting on differentiated B cells. We speculate that in these culture systems, these "terminal differentiating hormones" regulate the final pathway of differentiation, whereas the pre-B-synergizing activity supports early stem cells that can then respond to the other differentiating hormones.

Animals↗

PubMed1988

Effects of transcutaneous scopolamine and depth on diver performance.

Transdermal scopolamine is an effective anti-motion-sickness medication that has less CNS side effects at normal ambient pressure than orally ingested agents. To see whether it has an effect on performance at depth, 24 healthy sport divers were exposed to depths equivalent to 5 m (1.5 ATA) and 36 m (4.8 ATA) in a dry recompression chamber, breathing air and wearing a skin patch containing either scopolamine or inactive placebo. Patches and dive depths were presented in a counterbalanced, double-blind experimental design. Tests of sentence comprehension, simple arithmetic, and manual dexterity were used to evaluate psychometric and cognitive performance. Drug side effects were recorded. The Bennett Hand Tool Dexterity Test was evaluated for its suitability for repeated measures testing, and found to be robust. Manual dexterity and sentence comprehension were significantly impaired at depth whereas arithmetic skills were not. No significant effects on diver performance from transdermal scopolamine were seen. Certain side effects such as blurred vision were more common with scopolamine than with placebo. The use of transdermal scopolamine as an antiemetic during diving operations deserves field evaluation.

Administration, Cutaneous↗

PubMed1987

A stromal cell line from myeloid long-term bone marrow cultures can support myelopoiesis and B lymphopoiesis.

The production of B lymphocytes and myeloid cells occurs in the bone marrow in association with a supporting population of stromal cells. To determine whether these processes are dependent upon the same or different populations of stromal cells, stromal cell lines were generated from the adherent layer of a Dexter type long-term bone marrow culture. These cultures support myeloid cells and their precursors, a B cell precursor, and the adherent layer cells with support B cell differentiation under appropriate conditions. Two of the lines examined, S10 and S17, express class I histocompatibility antigens but not other hemopoietic cell surface determinants such as Thy-1, Lyt-1, Ig, Ia, Mac-1, or BP-1. Both lines could support myelopoiesis under Dexter conditions upon seeding with nylon wool-passed bone marrow. The nylon wool passage depletes stromal cells capable of forming adherent layers in vitro but retains hemopoietic precursors. The number of cells and colony-forming units-granulocytes/macrophages in the nonadherent cell population recovered 3 wk post-seeding had increased 19-fold and 10-fold, respectively, in the reseeded cultures of S10 and S17. After 3 wk of growth in Dexter conditions, the reseeded cultures were transferred to conditions optimal for B cell differentiation described by Whitlock and Witte. After 4 wk of growth, hemopoietic cells were consistently recovered from S17 cultures but not those of S10. A proportion of these cells from S17 cultures expressed the 14.8 antigen and were surface IgM positive. Surviving hemopoietic cells present in cultures of S10 were primarily macrophages. These findings indicate that S17 but not S10 can support both myelopoiesis and B lymphopoiesis and suggest that one stromal cell population has the capacity to form a hemopoietic microenvironment for both lineages.

Animals↗

PubMed1984

Production of T lymphocyte colony-forming units from precursors in human long-term bone marrow cultures.

T cell differentiation in human marrow was studied in Dexter type long-term bone marrow cultures. In these cultures, T lymphocyte colony-forming units (TL-CFU), E rosette-forming cells (E+), and T3+, T4+, and T8+ cells (assayed by indirect immunofluorescence) were found to be present for at least 7 weeks. It was investigated whether the existence of T cells in long-term culture resulted from the persistence of inoculated T lymphocytes or from the production by immature progenitors. No significant numbers of E+, T3+, T4+, or T8+ cells were detected in cultures that were established from E+ lymphocyte-depleted bone marrow, indicating little or no production of T lymphocytes from E-negative precursors. On the other hand, bone marrow cells purged of E+ lymphocytes did not contain TL-CFU, but appeared to regain high numbers of TL-CFU during Dexter culture; this suggested that an earlier step in T cell differentiation may take place in this culture system. The generation of TL-CFU in the E-negative long-term marrow cultures only occurred when an adherent stroma layer had been established in the culture flask; it did not require added mitogens or detectable interleukin 2 in the culture medium. TL-CFU in fresh marrow (TL-CFU II) are mature (E+, T3+) T cells and are capable of producing helper (T4+) and suppressor/cytotoxic (T8+) phenotype cells in colonies. The TL-CFU newly formed in E-depleted Dexter cultures (TL-CFU I) are distinct from this population, as they are E-negative and give rise to colonies of the helper type only. T3 cell depletion of the marrow inoculum prior to culture did not prevent the appearance of TL-CFU I in long-term culture; this suggests that TL-CFU I are derived from an E- and T3- precursor (pre-TL-CFU).

Bone Marrow Cells↗

PubMed1995

Management of impotence in a developing country.

Three hundred and seventy five impotent men attended our Andrology clinic between July 1988 and June 1993. Their ages ranged from 20-89 years. Associated factors were diabetes mellitus, testicular failure, trauma, venous leak and hyperprolactinaemia. We categorised them into subgroups of highly educated men with manual dexterity and financial ability but impairment of manual dexterity, financially able but illiterate men, and illiterate poor with or without manual dexterity. Penile prostheses were implanted in 15; 48 were treated with vasoactive substances; 4 with vacuum devices and two had ligation of venous leaks. However, 297 (79%) men did not get the treatment best suited for their problems and received only supplementary hormones and/or psychological reassurance. In the developing countries, the selection of the appropriate treatment modality for impotence is compounded by considerations of economic, social and educational factors.

Adult↗

PubMed1993

Lead exposure and the motor developmental status of urban six-year-old children in the Cincinnati Prospective Study.

The relationship between asymptomatic lead exposure and subtle deficits in intellectual attainment has been relatively well established by modern studies. However, neuromotor performance has rarely been the focus of these investigations. It was postulated that motor developmental outcomes may be more sensitive indicators of lead's adverse effects on the central nervous system as they are probably less confounded with social factors than cognitive and academic outcomes. A comprehensive neuromotor assessment battery was administered to 245 six-year-old urban inner-city children enrolled in the Cincinnati Lead Study. These children have been followed since birth with quarterly assessments of blood lead concentrations, medical status, and neurobehavioral development. Prior to covariate adjustment, neonatal, but not prenatal blood lead levels were associated with poorer scores on assessments of bilateral coordination, upper-limb speed and dexterity, and a composite index of fine-motor coordination. Averaged postnatal blood lead levels were also associated with lower scores on the aforementioned subtests as well as a measure of visual-motor control. Following statistical adjustment for covariates, neonatal blood lead levels were associated with poorer performance on a measure of upper-limb speed and dexterity and the fine-motor composite. Postnatal blood lead levels remained significantly associated with poorer scores on measures of bilateral coordination, visual-motor control, upper-limb speed and dexterity, and the fine-motor composite. Low to moderate lead exposure is associated with moderate deficits in gross and especially fine-motor developmental status. Results of this study provide support for recent initiatives to reduce the exposure of children to sources of environmental lead.

Age Factors↗

PubMed1994

Relationship of performance on the ERGOS work simulator to illness behavior in a workers' compensation population with low back versus limb injury.

A prospective blinded cohort study was performed to test for a difference in the pattern of physical activity factors measured with the ERGOS work simulator in subjects with low back injuries versus those with limb injuries. Also tested was the relationship between physical activity factors measured with the ERGOS and several psychological tests and measures of nonorganic pain behavior in subjects with low back pain. Subjects were 70 men, 22 to 64 years old, who attended a 2-week physical capacity assessment after undergoing rehabilitation for a work-related injury. In subjects with a complaint of low back pain, nonorganic pain behavior was measured with the Waddell score. In addition, two brief psychological tests, the Coopersmith Self-Esteem Inventory and analog self-rating of wellness, were administered. It was found that subjects with low back complaints underperformed globally in comparison with subjects with limb complaints. This underperformance was statistically significant (P < .05) for 7 of 13 strength variables and 2 of 7 dexterity variables. In the subjects with low back complaints, those who exhibited excessive illness behavior (Waddell score, 3 to 5) performed significantly worse on all 13 strength variables and on 3 of 7 dexterity variables. In the subjects with low back complaints, those with low self-assessment ratings were found to have a high Waddell score (P < .01) and to perform significantly worse (P < .05) on 12 of 13 strength variables and 6 of 7 dexterity variables. There were no significant relationships (P > .05) between Coopersmith Self-Esteem score and Waddell score or performance on ERGOS testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1996

Subjective effects of double gloves on surgical performance.

This randomised trial compared single gloves with combinations of double gloves to determine the subjective effects on comfort, sensitivity and dexterity in 32 surgeons. Glove perforation rates were also compared. Single gloves of the surgeon's normal size (method A) were used as control. Double gloves were worn in three different ways, selected randomly: normal gloves inside and gloves one-half size larger outside (method B); the larger gloves inside and the normal gloves outside (method C); and lastly, two pairs of gloves of normal size (method D). Double gloves by all three methods significantly protected against needle perforation of the inner gloves when compared with single gloves, but also significantly impaired comfort, sensitivity and dexterity. When the three types of double gloving were compared, there appeared to be advantages for method C for all modalities, but the differences did not reach statistical significance; also, more surgeons expressed a preference for method C. Perforation of the inner gloves was significantly less for double gloves than for single gloves. We conclude that double gloves often protect the surgeon against needle perforations, but are felt to impair comfort, sensitivity and dexterity.

Attitude of Health Personnel↗

PubMedDate not supplied

The cytoplasmic differentiation of jumelle Stylonychia.

Jumelle Stylonychia with oppositely oriented peristomes, which we obtained by artificial operations, carried on not only asexual reproduction and generation, but sexual reproduction and encystment as well, and seemingly tended to form a new species [7-10]. Our recent experimental analysis revealed that the sinister grew more and more dependent on its dextral sister organism, losing the ability of independent existence. Once cut off from the dexter, the organelles of the sinister ceased to regenerate, and the sinister died. But, if, when cutting, a portion is left connected to the dexter, the sinister will then be able to regenerate, and all its organelles become completely revealed. This indicates that dependence on the dexter weakened the metabolic functions of the sinister, primarily influencing the cytoplasm, which is manifested by the formation and development of its organelles. This, in effect, is a phenomenon of cytoplasmic differentiation induced by co-existence of the jumeaux.

Animals↗

PubMedDate not supplied

A comparison of two teaching simulations in preclinical operative dentistry.

The purpose of this study was to determine whether a ceramic tooth would be as effective as a natural tooth in teaching preclinical operative skills. Subjects consisted of all second-year students enrolled in a preclinical inlay course. Students were classified into high- and low-dexterity groups, randomly assigned to one of the tooth simulators, taught the same four procedures, and asked to keep a log of the amount of time spent on each. All students participated in a practical examination that consisted of preparing a cavity for a gold casting using a resin tooth. There were no statistically significant differences between students who prepared natural teeth and those who prepared ceramic teeth for either the qualitative practical examination score or the amount of preparation time required. High-dexterity students achieved significantly higher scores on the practical than did low-dexterity students, whether practicing on natural or ceramic teeth. The MOD onlay required significantly more time to complete than did any of the other preparations on both natural and ceramic tooth simulators. Written evaluations of the ceramic simulators revealed that students perceived ceramic teeth to be as good or better than natural teeth because of their anatomic uniformity.

Analysis of Variance↗

PubMed1976

[Morphology, topography and nomenclature of the human papillary muscles compared with mammalian].

On the internal or parietal surface of the left ventricle in man and in mammals are two papillary muscles, which are almost identical and well developed. In man, these muscles are known as the m. papillaris parietalis anterior sinister and the m. papillaris parietalis posterior dexter, in mammals, the m. papillaris parietalis cranialis sinister and caudalis dexter, or, in shorter form, mm. papillaris parietalis sinister et dexter. In the right ventricle in man, there are two papillary parietal muscles: the mm. papillares anteriores et posteriores. On the septum of this ventricle there is, as in mammals, a muscle called the m. papillaris septalis medialis seu subarteriosus. Beside it are one or several smaller muscles, varying from one individual to another: the mm. papillares septales accessorii seu parvi. In the right ventricle of the mammalian heart is found, in addition to the m. parietalis septalis subarteriosus, already mentioned, a m. papillaris caudalis, more or less well developed in some species and, in the majority of mammals, the m. papillaris septalis cranials, which is always well developed. In certain mammals, there is, in rare cases, a m. papillaris septomarginalis seu parietalis. It may be said, in conclusion, that, in a large number of mammals, there is, on the internal surface of the external wall of the right ventricle, a reasonably well developed m. papillaris parietalis.

Anatomy, Comparative↗

PubMed2007

Robotic surgery in the pediatric airway: application and safety.

OBJECTIVE: To assess the application and safety of transoral robotic surgery in the pediatric airway. DESIGN: An institutional review board-approved study. Experimental laryngeal surgery was performed on 4 pediatric cadaver larynxes as controls. Application of robotic equipment for laryngeal surgery was attempted on 5 patients. SETTING: Tertiary care pediatric medical center. PATIENTS: Five patients with laryngeal cleft and 4 pediatric cadaver larynxes. INTERVENTIONS: (1) The da Vinci Surgical Robot (Intuitive Surgical Inc, Sunnyvale, Calif) was used on 4 cadaver larynxes and assessed for the dexterity, precision, and depth perception that it allowed the surgeon during laryngeal surgery. Procedures were documented with still and video photography. (2) The da Vinci Surgical Robot was used through a transoral approach to attempt repair of a laryngeal cleft in 5 pediatric patients who were under spontaneously breathing general anesthesia. RESULTS: (1) Use of the surgical robot on cadaver larynxes provided great dexterity and precision, delicate tissue handling, good 3-dimensional depth perception, and relatively easy endolaryngeal suturing. (2) The surgical robot could not be used for repair of laryngeal cleft on 3 patients owing to limited transoral access. However, 1 patient with a type 1 laryngeal cleft and 1 patient with a type 2 laryngeal cleft underwent transoral robotic repair with great success. CONCLUSIONS: Surgical robots provide the ability to manipulate instruments at their distal end with great precision, increased freedom of movement, and excellent 3-dimensional depth perception. The size of the equipment can be a limiting factor with regard to the application and success of the transoral approach to airway surgery. We believe that further advances in device technology and a new generation of robotic equipment will facilitate the incorporation of surgical robotics in the advancement of minimally invasive endoscopic airway surgery.

Adolescent↗