Robotic control in knee joint replacement surgery.

A brief history of robotic systems in knee arthroplasty is provided. The place of autonomous robots is then discussed and compared to more recent 'hands-on' robotic systems that can be more cost effective. The case is made for robotic systems to have a clear justification, with improved benefits compared to those from cheaper navigation systems. A number of more recent, smaller, robot systems for knee arthroplasty are also described. A specific example is given of an active constraint medical robot, the ACROBOT system, used in a prospective randomized controlled trial of unicondylar robotic knee arthroplasty in which the robot was compared to conventional surgery. The results of the trial are presented together with a discussion of the need for measures of accuracy to be introduced so that the efficacy of the robotic surgery can be immediately identified, rather than have to wait for a number of years before long-term clinical improvements can be demonstrated.

Computer-assisted hip resurfacing surgery using the acrobot navigation system.

The authors have previously reported on the laboratory development of the Acrobot Navigation System for accurate computer-assisted hip resurfacing surgery. This paper describes the findings of using the system in the clinical setting and including the improvements that have been made to expedite the procedure. The aim of the present system is to allow accurate planning of the procedure and precise placement of the prosthesis in accordance with the plan, with a zero intraoperative time penalty in comparison to the standard non-navigated technique. At present the navigation system is undergoing final clinical evaluation prior to a clinical study designed to demonstrate the accuracy of outcome compared with the conventional technique. While full results are not yet available, this paper describes the techniques that will be used to evaluate accuracy by comparing pre-operative computed tomography (CT)-based plans with post-operative CT scans. Example qualitative clinical results are included based on visual comparison of the plan with post-operative X-rays.

Preoperative planning and intraoperative guidance for accurate computer-assisted minimally invasive hip resurfacing surgery.

Hip resurfacing is an alternative to total hip replacement (THR) and is particularly suitable for the younger, more active patient. However, it is a more demanding procedure. This paper describes a system that enables the surgeon to plan the surgery preoperatively with optimally sized and placed components, and then transfer this plan to an intraoperative system that registers computer models to the real patient and tracks surgical tools, allowing the surgeon to ensure that the bone is resected correctly and that the components are fitted in accordance with the plan. The paper describes a series of instruments used with the system which are locked to the bone. These instruments serve the dual purpose of soft tissue retraction and bone immobilization. The system will shortly be the subject of laboratory and clinical evaluation. Registration, a cornerstone of the tracked instrument system, has been tested, and accuracy measures are provided. Experimental results for the remainder of the system will be provided after clinical trials.

Asymptomatic perianal shedding of herpes simplex virus in patients with acquired immunodeficiency syndrome.

OBJECTIVE: To determine the frequency of asymptomatic perianal shedding of herpes simplex virus (HSV) in adult patients with acquired immunodeficiency syndrome (AIDS). DESIGN: Cross-sectional study. SETTING: A 1000-bed, state-supported hospital in Brazil that provides comprehensive health care. PATIENTS: Eighty-two consecutively hospitalized patients with AIDS (Centers for Disease Control and Prevention class C). MAIN OUTCOME MEASUREMENT: Specimens for HSV culture were obtained with premoistened swabs of the perianal region at approximately 7-day intervals during the hospitalization of each patient. After the specimens were inoculated into cultures of human foreskin and Vero cells, supernatants of cultures showing the cytopathic effect characteristic of HSV infection were tested for virus in a confirmatory immunoenzymatic assay. Typing of HSV was performed by polymerase chain reaction amplification of HSV-1- and HSV-2-specific DNA polymerase sequences. RESULTS: On early into the study, 12 (15%) of 82 patients had perianal ulceration and 70 did not. None of the patients in the latter group developed perianal ulcers during the study period, but HSV was isolated at least once from 17 (24%) of them. Nine of the 17 asymptomatic perianal shedders had a mean of 3 perianal swabs collected before the first HSV isolation, and 11 (65%) of 17 had a total of 18 perianal swabs collected 8 to 62 days after the HSV isolation. All postpositive samples were negative for HSV except 1 obtained from a patient 13 days after the first positive sample. Twelve of the 17 asymptomatic perianal shedders of HSV were followed up clinically for 8 to 62 days after the first episode of shedding and none developed perianal ulceration. CONCLUSIONS: We conclude that asymptomatic perianal shedding of HSV is common in patients with AIDS, even among those without a history of perianal HSV lesions. This shedding appears to be short-lived, intermittent, and not associated with early subsequent development of perianal ulcers. These findings present a new perspective on the natural course of perianal HSV infection in patients with AIDS.

A computer-assisted training/monitoring system for TURP structure and design.

A generic framework for a computer-assisted system for both soft tissue endoscopic surgery and surgical training is being researched and developed. The concept demonstrator is a specific system for transurethral prostatic resection (TURP). The main novelty of the research is that it is not confined to an in vitro trainer system. An in vivo monitoring version of the system, for use in the operating theater, is also being researched. This paper presents the framework's structure and design using the United Modeling Language. It also discusses and justifies the underlying information technologies chosen to implement this approach. Object-oriented concepts and well-proven mathematical tools have been adopted as the foundation of this research and development. The rationale for having chosen such tools is presented. The objectives are to arrive at a system which is modular, general, and reusable.

Mercury content in shark species from the South-Eastern Brazilian coast.

We present here the first results of Hg concentrations in three small shark species (Rhizoprionodon lalandei, R. porosus and Mustelus higmani) from the SE Brazilian coast. Mercury concentrations in R. lalandei ranged from 21.5 to 280.0 ng.g-1 dry weight (d.w.) (average 74.6 ng.g-1 d.w.; 17.9 ng.g-1 wet weight). In R. porosus, concentrations ranged from 7.6 to 90.5 ng.g-1 d.w. (average 42.2 ng.g-1 d.w., 9.4 ng.g-1 wet weight), whereas in M. higmani, concentrations ranged from 13.0 to 162.8 ng.g-1 d.w. (average 54.9 ng.g-1 d.w., 13.4 ng.g-1 wet weight). These concentration ranges are very low compared with values reported for other large shark species of the Southwestern Atlantic Ocean. There was a significant positive correlation between Hg concentrations and individual size, suggesting that biomagnification is occurring in these animals.

Phosphorous and sulfur nutrition modulate antioxidant defenses in Myracrodruom urundeuva plants exposed to arsenic.

We investigated if plant nutrition and antioxidant system activation are correlated features of arsenic (As)-tolerance in Myracrodruom urundeuva. Plants were grown for 120 days in substrates with 0, 10, 50 and 100mg Askg(-1) and its As-tolerance was demonstrated. As-concentrations greater than 10mgkg(-1) decreased plant growth and photosynthesis but did not induce plant death. Plants coupled alterations in stomatal conductance and transpiration to avoid As-deleterious effects to the photosynthetic apparatus. As-toxicity in M. urundeuva was due to lipid peroxidation induced by hydrogen peroxide accumulation. Ascorbate peroxidase (APX) and gluthatione peroxidase (GPX) had central roles in hydrogen peroxide (H2O2) scavenging in leaves, and their activities were linked to changes in redox potentials (ascorbate and glutathione pools). APX and GPX inactivation/degeneration led to H2O2 accumulation and related lipid peroxidation. Increased phosphorus (P) and sulfur (S) concentrations in leaves were related to increased APX and GPX activities by stimulating increases in glutathione biosynthesis. We concluded that P and S nutrition were directly linked to As-tolerance in M. urundeuva plants by increasing antioxidant system activities.

Bivalirudin for the treatment of patients with confirmed or suspected heparin-induced thrombocytopenia.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is an adverse immune-mediated response to unfractionated heparin and, less commonly, low molecular weight heparin. It is associated with a high thrombotic risk and the potential for limb and life-threatening complications. Argatroban is the only approved and currently available anticoagulant for HIT treatment in the USA. OBJECTIVES: To report safety and efficacy outcomes with bivalirudin for HIT treatment. METHODS: We retrospectively examined records from our registry of patients with a suspected, confirmed or previous history of HIT and who had received bivalirudin for anticoagulation in a single tertiary-care center over a 9-year period. RESULTS: We identified 461 patients who received bivalirudin: 220 (47.7%) were surgical patients, and 241 (52.3%) were medical patients. Of this population, 107 (23.2%) were critically ill, and 109 (23.6%) were dialysis-dependent. Suspected, confirmed and previous history of HIT were reported in 262, 124 and 75 patients, respectively. Of 386 patients with suspected or confirmed HIT, 223 patients (57.8%) had thrombosis at HIT diagnosis. New thrombosis was identified in 21 patients (4.6%) while they were on treatment with therapeutic doses of bivalirudin. No patient required HIT-related amputation. Major bleeding occurred in 35 patients (7.6%). We found a significant increase in major bleeding risk in the critically ill population (13.1%; odds ratio 2.4, 95% confidence interval 1.2-4.9, P = 0.014). The 30-day all-cause mortality rate was 14.5% (67 patients), and eight of 67 (1.7%) deaths were HIT-related. CONCLUSION: Bivalirudin may be an effective and safe alternative option for the treatment of both suspected and confirmed HIT, and appears to reduce the rate of HIT-related amputation.

Zinc tolerance modulation in Myracrodruon urundeuva plants.

We investigated Zn tolerance and related tolerance mechanisms of Myracrodruon urundeuva by evaluating the growth (biomass production, pigment content, and photosynthetic activity) and antioxidant systems (redox potential and antioxidant enzyme activities) of seedlings exposed to increasing Zn doses. Plants were grown for 120 days in substrates with 0, 50, 80, 120 and 200 mg Zn kg(-1) and demonstrated Zn-tolerance. Zn doses greater than 80 mg Zn kg(-1) were phytotoxic but not lethal, and Zn toxicity under these conditions was imposed by oxidative stress caused by hydrogen peroxide (H2O2) accumulation and related lipid peroxidation. Zn tolerance in M. urundeuva is linked to the activity of antioxidant systems in their leaves that are modulated by that metal: both superoxide dismutase (SOD) and catalase (CAT) were always higher in the presence of Zn; lower Zn doses stimulated ascorbate peroxidase (APX) and glutathione reductase (GR) activities, but enzyme activity was inhibited at high doses; APX appeared to be the main peroxidase in H2O2 scavenging as stimulated guaiacol peroxidase (GPX) activity was not sufficient to avoid H2O2 accumulation at higher Zn doses; the modulation of APX and GR activities was linked to changes in the redox status of leaves.

Phosphorus improves arsenic phytoremediation by Anadenanthera peregrina by alleviating induced oxidative stress.

Due to similarities in their chemical behaviors, studies examining interactions between arsenic (As)--in special arsenate--and phosphorus (P) are important for better understanding arsenate uptake, toxicity, and accumulation in plants. We evaluated the effects of phosphate addition on plant biomass and on arsenate and phosphate uptake by Anadenanthera peregrina, an important Brazilian savanna legume. Plants were grown for 35 days in substrates that received combinations of 0, 10, 50, and 100 mg kg(-1) arsenate and 0, 200, and 400 mg kg(-1) phosphate. The addition of P increased the arsenic-phytoremediation capacity of A. peregrina by increasing As accumulation, while also alleviating As-induced oxidative stress. Arsenate phytotoxicity in A. peregrina is due to lipid peroxidation, but not hydrogen peroxide accumulation. Added P also increased the activity of important reactive oxygen species-scavenging enzymes (catalase and ascorbate peroxidase) that help prevent lipid peroxidation in leaves. Our findings suggest that applying P represents a feasible strategy for more efficient As phytoremediation using A. peregrina.

Threshold photoelectron spectroscopy of ozone.

Threshold photoelectron spectrum of ozone is presented for the first time at a resolution of 21-38 meV using synchrotron radiation in the energy region of 12-21 eV. The ionization energies of the first ionized states were determined and an interpretation of the O3 spectrum with respect to its first three ionic states, 1 2A1, 1 2B2, and 1 2A2, is presented. Above 16 eV the enhancement of the intensities of the 2 2B1, 3 2A1, and 4 2B2 band systems due to the contribution of indirect processes was observed, not accessible by conventional photoelectron spectroscopy. It was also resolved and assigned the extensive vibrational structures of ozone. Between 15.5 and 18.5 eV the main band contours are similar to those found in conventional photoelectron spectroscopy, except that our threshold photoelectron spectrum reveals extensive additional vibrational structures. The band 2 2B1 was found to present an irregular vibrational spacing DeltaE, with a minimum value of 80 meV at approximately 16.47 eV.

Regional odontodysplasia: report of a case involving two separate affected areas.

The purpose of this study was to report in a 12-year old white child a rare clinical condition called regional odontodysplasia. The diagnosis was based on clinical and radiographic findings. Due to the patient's concern over appearance, the treatment involved extracting the affected teeth and subsequently placing partial removable prostheses, thus providing the patient better function and appearance. The teeth that were removed were examined histologically, both in routine preparation stained by hematoxyline and eosin, and in ground sections.

A computer assisted surgical trainer for transurethral resection of the prostate.

PURPOSE: We developed a realistic and reusable computer assisted surgical training system for transurethral resection of the prostate. MATERIALS AND METHODS: A disposable prostate model is housed in a model abdomen. A software program that provides a 3-dimensional (D) illustration of the prostate model was developed. Resectoscope position with reference to the model is tracked by infrared emitting diodes attached to it, which in turn are monitored by an optical tracker. Movement of the loop in relation to the resectoscope is measured by a potentiometer attached to the working element. RESULTS: Resectoscope position was shown on the monitor superimposed on a 3-D image of the prostate model in real time. A 2-D image showed the amount of tissue resected and the proximity of the loop to the capsule. A series of thumbnail images were shown and the highlighted image represented the current position of the resectoscope. It is intended that this system should be interactive, providing continuous feedback on the progress of resection and acting as an interactive training aid. During the course of validating the system several problems were noted, mainly with model movement and permanent deformation of the model during resection. CONCLUSIONS: This system can exist as a stand-alone training aid after the problems have been addressed. The potential application of an in vivo system for routine transurethral prostate resection has great implications for training and quality control.

Beta-thalassemia mutations in the Portuguese population.

In this study we have carried out haplotype analysis on the beta-globin gene cluster and characterized the beta-thalassemia mutation by oligonucleotide hybridization in 14 patients with thalassemia major and 5 with sickle cell/beta-thalassemia originating from southern Portugal. We found that three mutations, namely the beta(0)-39, beta(0) IVS-1 nt 1 and beta(+) IVS-1 nt 110 are prevalent accounting for 53%, 32% and 10% of the beta-thalassemia chromosomes respectively. In general each mutation was associated with a specific chromosomal haplotype; the beta(0)-39 mutation, however, was linked to three different haplotypes. These results indicate that three oligo-probes complementary to the most common mutations allow prenatal diagnosis by oligonucleotide analysis in 96% of the couples at risk of having offspring with thalassemia major in southern Portugal.

Unusual molecular basis of Hb H disease in the Azores Islands, Portugal.

An Azorean family with Hb H disease (10% Hb H) was studied in order to elucidate its molecular basis. DNA studies on the patient only revealed a 4.2 kb "leftward" deletion of paternal origin which implies the co-inheritance of a nondeletional alpha-thalassemia determinant. Restriction endonuclease and oligonucleotide analysis allowed the exclusion of five point mutations: initiation codon (at both alpha 1- and alpha 2-globin genes), IVS-I donor splice junction pentanucleotide deletion, codon 125 CTG----CCG substitution, and Saudi Arabian polyadenylation signal mutation. These findings suggest that the molecular basis of this form of Hb H disease is probably different from those described previously.