[Unilateral subthalamic stimulation in the treatment of advanced Parkinson's disease]

INTRODUCTION

The use of unilateral subthalamic stimulation (USTS) in the treatment of advanced Parkinson's disease can be effective and offer a series of advantages on comparing this technique with bilateral subthalamic stimulation (BSTS).

PATIENTS AND METHODS

We studied 35 consecutive patients: 22 with BSTS and 13 with USTS (six left and seven right). The epidemiological features and the scores on the functional assessment scales -Hoehn and Yahr, Schwab and England, and the Unified Parkinson's Disease Rating Scale (UPDRS) I to IV- were not significantly different in the two groups, except for the Hoehn and Yahr in off (USTS: 3.3 +/- 0.3; BSTS: 4.1 +/- 0.2; p = 0.004).

RESULTS

The overall percentages of improvement six months after surgery were UPDRS I: 12%; II: 21.6%; III-medication off/stimulator on: 30.6% (with respect to the baseline off state); III-on/on: 8.8% (with respect to the baseline on state); IV: 48.9%. Reduction in the levodopa equivalent dose: USTS: 26.3%; BSTS: 17%. These percentages of improvement were not significantly different in the two groups. If we consider the motor scale in medication-off and stimulator-on in the sixth month and we compare it with the same in the off state before surgery, the axial motor symptoms improved by 17.1% (USTS) and 25% (BSTS); in the extremities, USTS: 39.1% in the limbs contralateral to the implanted electrode, and 14.5% in the ipsilaterals; BSTS: right extremities, 32.6%; left extremities, 31.5%. No significant differences were found on comparing the electrical power consumed by the electrodes in the two groups of patients in the sixth month of treatment.

CONCLUSIONS

USTS was effective in improving the axial symptoms. In our series, the reduction in medication following surgery was similar to that of the patients with BSTS.

Computer simulation of damage on distal femoral articular cartilage after meniscectomies

It is commonly accepted that total or partial meniscectomies cause wear of articular cartilages that leads to severe damage in a period of few years. This also produces alteration of the biomechanical environment and increases articular instability, with a progressive and degenerative arthrosic pathology. Due to these negative consequences, total meniscectomy technique has been avoided, with a clear preference for partial meniscectomies. Despite the better results obtained with this latter technique, it has been demonstrated that the knee still suffers progressive long-term wear, which alters the properties of the surface of articular cartilage. In this paper, a phenomenological isotropic damage model of articular cartilage is presented and implemented in a finite element code. We hypothesized that there is a relation between the increase of shear stress and cartilage degeneration. To confirm the hypothesis, the obtained results were compared to experimental ones. It is used to investigate the effect of meniscectomies on articular damage in the human knee joint. Two different situations were compared for the tibio-femoral joint: healthy and after meniscectomy. The distribution of damaged regions and the damage level distribution resulted qualitatively similar to experimental results, showing, for instance that, after meniscectomy, significant degeneration occurs in the lateral compartment. A noteworthy result was that patterns of damage in a total meniscectomy model give better agreement to clinical results when using relative increases in shear stress, rather than an absolute shear stress criterion. The predictions for partial meniscectomies indicated the relative severity of the procedures.

Biomechanical modeling of refractive corneal surgery

The aim of refractive corneal surgery is to modify the curvature of the cornea to improve its dioptric properties. With that goal, the surgeon has to define the appropriate values of the surgical parameters in order to get the best clinical results, i.e., laser and geometric parameters such as depth and location of the incision, for each specific patient. A biomechanical study before surgery is therefore very convenient to assess quantitatively the effect of each parameter on the optical outcome. A mechanical model of the human cornea is here proposed and implemented under a finite element context to simulate the effects of some usual surgical procedures, such as photorefractive keratectomy (PRK), and limbal relaxing incisions (LRI). This model considers a nonlinear anisotropic hyperelastic behavior of the cornea that strongly depends on the physiological collagen fibril distribution. We evaluate the effect of the incision variables on the change of curvature of the cornea to correct myopia and astigmatism. The obtained results provided reasonable and useful information in the procedures analyzed. We can conclude from those results that this model reasonably approximates the corneal response to increasing pressure. We also show that tonometry measures of the IOP underpredicts its actual value after PRK or LASIK surgery.

Influence of the tunnel angle in ACL reconstructions on the biomechanics of the knee joint

BACKGROUND

A high tension in anterior cruciate ligament grafts affects both graft and knee functional performance. Clinical observations suggest that impingement of the graft against the posterior cruciate ligament might cause high graft tensions. Also, meniscal injury has been well documented in association with damage in the anterior cruciate ligament.

METHODS

In this paper, we present the results obtained in a three-dimensional finite element model of the human knee, corresponding to different aspects of anterior cruciate ligament reconstruction with bone-patellar tendon-bone grafts. This model was used to investigate the effect of the angle in the coronal plane of femoral and tibial tunnels. Firstly, graft tension was computed in a knee moved from 0 degrees to 60 degrees of flexion and the results were compared with experimental ones obtained by other authors. Secondly, the resulting kinematics under an anterior load of 134 N was compared to that of the intact knee.

FINDINGS

The obtained results showed that the closest anterior tibial translation to that of the intact knee was obtained with femoral and tibial tunnels with angles of 60 degrees. In this same case, a lower graft tension was also obtained. The results demonstrated noticeable increases in the meniscal stresses after anterior cruciate ligament reconstruction.

INTERPRETATION

Our results showed that impingement only depends on the femoral tunnel angle. On the contrary, laxity principally depends on the tibial tunnel angle. The angle of the femoral tunnel affects the graft tension while the tibial tunnel affects laxity, meniscal stresses and strains.

Sleep disturbances, socioeconomic status, and seizure control as main predictors of quality of life in epilepsy

Improving quality of life is the most important goal for patients with epilepsy. To recognize the factors associated with quality of life in patients with epilepsy in Mexico, we performed a cross-sectional survey using the Quality of Life in Epilepsy 31 (QOLIE-31) inventory to assess the quality of life of 401 adult patients with epilepsy at the National Institute of Neurology and Neurosurgery of Mexico. Clinical and demographical data were collected. Multiple regression was used to determine which factors affected quality of life in our patients. The variables that most strongly predicted a lower QOLIE-31 total score after multiple regression were sleep disorders (P<0.001), socioeconomic status (P<0.001), female gender (P=0.002), and high seizure frequency (P=0.001). In our study, neither depression nor time of evolution of epilepsy had significant influence on QOLIE-31 scores.

Basiliximab in lung transplantation: preliminary experience

BACKGROUND

Basiliximab is a chimeric anti-interleukin-2 monoclonal antibody that has shown safety and efficacy in the prophylaxis of acute organ rejection in renal, liver, heart, and kidney-pancreas transplantation (Tx). The aim of this study was to present our initial experience with the use of Basiliximab in lung Tx.

METHODS

Basiliximab (2 doses of 20 mg on day 0 and day 4) was administered to 16 patients treated with cyclosporine, azathioprine, and steroids between September 13, 2001 and August 26, 2003, including 12 men and 4 women patients with a mean age of 56.5 years (range, 19-69). The indication for use in transplantations were: reduced renal function (n = 14), post-Tx acute renal failure (n = 1) and steroid-resistant acute rejection (n = 1). Eight double-lung and eight single-lung Tx were performed for emphysema (n = 6), idiopathic pulmonary fibrosis (n = 7), silicosis (n = 2), and cystic fibrosis retransplantation (n = 1).

RESULTS

The incidence of acute rejection was 16.6% (2 patients). Infections included cytomegalovirus (CMV) 33.3% (n = 4), bacterial 16.6% (n = 2), and fungal 8.3% (n = 1). Two patients died in the postoperative period and another at 3 months. There was no reaction to the medicine, and no malignancies or Bronchiolitis Obliterans Syndrome (BOS) during a follow-up period of more than 1 year in 10 patients.

CONCLUSION

Basiliximab appeared to reduce the incidence of acute organ rejection and showed a good safety profile in terms of infections and adverse events.

A three-dimensional finite element analysis of the combined behavior of ligaments and menisci in the healthy human knee joint

We present here a three-dimensional FE model of the healthy human knee that included the main structures of the joint: bones, all the relevant ligaments and patellar tendon, menisci and articular cartilages. Bones were considered to be rigid, articular cartilage and menisci linearly elastic, isotropic and homogeneous and ligaments hyperelastic and transversely isotropic. Initial strains on the ligaments and patellar tendon were also considered. This model was validated using experimental and numerical results obtained by other authors. Our main goal was to analyze the combined role of menisci and ligaments in load transmission and stability of the human knee. The results obtained reproduce the complex, nonuniform stress and strain fields that occur in the biological soft tissues involved and the kinematics of the human knee joint under a physiological external load.

A finite element simulation of the effect of graft stiffness and graft tensioning in ACL reconstruction

BACKGROUND

The anterior cruciate is the most frequent knee ligament to be totally disrupted. Surgical reconstruction of the anterior cruciate ligament is a common practice to treat the disability or chronical instability of knees due to anterior cruciate ligament insufficiency. Some of the factors that influence the success or failure of the anterior cruciate ligament reconstruction are the integrity of secondary restraints, the preoperative laxity of the knee, the status of the articular and meniscal cartilages, the selection of the graft material, the surgical technique, the graft tension and the postoperative rehabilitation.

METHODS

In this paper we present and discuss the results obtained with a three-dimensional finite element model of the human knee joint corresponding to different aspects of human anterior cruciate ligament reconstruction. In particular, this model was used to investigate the effect of graft stiffness and graft tensioning on the knee joint biomechanics. The initial graft tension was set to 0, 20, 40 or 60 N with the knee at 0 degrees , 30 degrees and 60 degrees of flexion. Three different stiffnesses corresponding to those of patellar tendon, gracilis and quadrupled semitendinosus grafts were analyzed.

FINDINGS

The resulting kinematics in each of these cases under an anterior load of 134 N was compared to that of the intact knee. The obtained results showed that, after reconstruction, the closest anterior tibial translation to that of the intact knee is obtained with a bone-patellar tendon-bone graft with a pretension of 60 N.

INTERPRETATION

However, this initial tension produces an important additional stress in the graft during the knee movement. This may cause problems in revascularization and remodelling during the postoperative healing process. A lower pretension of about 40 N should therefore be recommended in the present conditions.

Finite element analysis of the effect of meniscal tears and meniscectomies on human knee biomechanics

BACKGROUND

Many authors have suggested that the high levels of shear and tensile stresses that appear in the articular cartilage after meniscectomy are partly responsible for cartilage pathologies, such as osteoarthrosis.

METHODS

In this paper, we investigate the effect of meniscal tears and meniscectomies on the human knee joint. Solid models of the tibia, femur, menisci and cartilage were generated from MRI images. A three-dimensional finite element model was developed that included the femur, tibia, cartilage layers, menisci and ligaments. The femur and tibia were considered to be rigid, the articular cartilage and menisci to be linearly elastic, isotropic and homogeneous and the ligaments were modelled as hyperelastic. Three different situations were compared: a healthy tibio-femoral joint, a tibio-femoral joint with tears in one meniscus and a tibio-femoral joint after meniscectomy.

FINDINGS

The minimal principal stresses corresponding to a compressive load at 0 degrees flexion were obtained for the posterior zone of the medial meniscus and the corresponding region of the articular cartilage. Under an axial femoral compressive load, the maximal contact stress in the articular cartilage after meniscectomy was about twice that of a healthy joint.

INTERPRETATION

This fact could partially explain the cartilage damage and degeneration that have been observed after meniscectomy.

Enzymolysis approach to compare cu availability from human milk and infant formulas

The purpose of the present paper is to develop an easy and quick in vitro method to compare copper availability from breast milk and infant formulas. This study focuses on the differences caused by the use of pH 2.0 (adult gastric pH) or pH 5.0 (newborn gastric pH) in the first stage of the enzymolysis. pH affects Cu solubility, a possible estimator of the availability. Selection of a digestor, times of enzymolysis, centrifugation parameters, and Cu determination by ETAAS were discussed as well. Percentage of Cu solubility was larger from breast milk (gastric pH 2.0, 65.3 +/- 14.0 vs 40.0 +/- 13.9%; gastric pH 5.0, 61.2 +/- 16.5 vs 26.6 +/- 10.3%), but the soluble content was larger from infant formulas for both pHs (gastric pH 2.0, 245.3 +/- 82.1 vs 113.0 +/- 103.4 ng mL(-1); gastric pH 2.0, 169.3 +/- 76.9 vs 75.3 +/- 21.9 vs ng mL(-1)).

[Chickenpox outbreak in Herrera del Duque, Badajoz, Spain]

INTRODUCTION

Chickenpox is a worldwide disease with high morbidity but few complications, although complications can be sevre in immunocompromised individuals and healthy adults. The annual chickenpox rate declared to the National Notification Disease Surveillance System is approximately 5 cases per 1,000 inhabitants in Extremadura (Spain). The aim of this study was to identify and describe the characteristics and cost of an epidemic outbreak of chickenpox in Extremadura.

METHODS

Between November 2000 and March 2001, a descriptive study was performed. Cases of chickenpox were actively sought in a cohort of schoolchildren in Herrera del Duque (Badajoz). The protocols of the Monitoring Network of the Autonomous Community of Extremadura was used for case definition. Microbiological confirmation was performed by isolation of the virus and the presence of IgM and IgG markers in serum. We analyzed the direct and indirect tangible costs as well as the intangible costs of the outbreak.

RESULTS

Seventy-five cases were identified, of which 94.7% occurred in children aged between 1-9 years, mainly boys. The attack rate was 18.5 cases per 1,000 inhabitants and 68.2% occurred in children aged less than 10 years charing a home. The clinical course was benign, without hospital admissions or complications. A total of 71.6% of children aged between 3 and 8 years were susceptible. A possible temporary aggregation of cases in the school was analyzed and a relative risk of 5.01 (p < 0.0001) was obtained. The virus was isolated in the 4 vesicle samples studied and serology was positive (IgM) in the 9 serum samples studied. The total cost of the outbreak was of 927,21 e, with a mean of 12,53 e per case and 205 school days lost.

CONCLUSION

A chickenpox outbreack was confirmed in Herrera del Duque, with person-to-person transmission, affecting children aged between 1 and 9 years. The high susceptibility of the pupils, the characteristics of teaching, and the meetings prior to the carnivals played a determining role in the transmission of the epidemic. The estimated cost of this outbreak was 76% less than the cost that would have been generated by single-dose vaccination of the 75 individuals who contracted the disease.

[Evolution and treatment response in microscopic colitis]

AIM

To study the clinical characteristics, treatment response and evolution in patients with microscopic colitis.

MATERIAL AND METHODS

We performed a retrospective analysis of 24 patients (15 with collagenous colitis and 9 with lymphocytic colitis). Clinical and diagnostic features, treatment response and evolution according to the presence of maintenance therapy were evaluated.

RESULTS

The mean age of the patients was 59.7 years and most were male. Nine patients took non-steroidal anti-inflammatory drugs (NSAID). No significant association was found with other drugs. Four patients presented associated rheumatological disease. Most patients presented insidious-onset diarrhea without pathological products, which was frequently associated with other symptoms (abdominal pain, bloating, weight loss, asthenia, tenesmus, and incontinence). Seven patients showed a slight increase in globular sedimentation rate. Fat in stools and radiological investigations (transit and opaque enema) were normal in patients who underwent these tests. Endoscopy revealed non-specific alterations in 42% of the patients while results were normal in the remaining patients. One patient showed clinical improvement on withdrawal of NSAIDs and 4 patients improved spontaneously. Clinical response was achieved in 7 of 13 patients treated with antimotility drugs, in 8 of 9 patients treated with salicylates, in 3 treated with oral corticoids, in 1 treated with cholestyramine and in 1 treated with topical budesonide. Nineteen patients required no maintenance therapy, 4 were administered salicylates and 1 was administered cholestyramine. After a mean follow-up of 42 months, evolution was chronic and intermittent in 14 patients and chronic and continuous in 1; 9 patients presented a single episode. No significant differences were found between patients administered maintenance therapy and those who were not or between collagenous colitis and lymphocytic colitis in the parameters analyzed.

CONCLUSIONS

Microscopic colitis constitutes a group of diseases characterized by chronic diarrhea, few systemic effects and minimal radiological and/or endoscopic alterations. Evolution is characterized by recurrent episodes, with good response to treatment with cholestyramine, salicylates or corticoids when required.

[Autoimmune hepatitis with prolonged IGM antibodies to HAV. Are serological markers reliable in ruling out a diagnosis of autoimmune hepatitis?]

We present the case of a 44-year-old woman who was referred to us for jaundice, choluria and acholia. Review of the patient's clinical history revealed that tests for hepatitis A virus (HAV) IgM antibody had been positive 4 and 2 years previously and continued to be so. The patient showed a score of 16 in the International Autoimmune Hepatitis Group's system when the HAV marker was not taken into account and a score of 13 when this marker was taken into account. The persistence of this viral marker for so many years in such patients is probably associated with polyclonal hypergammaglobulinemia. Consequently, we believe that the inclusion of this antibody as a negative datum in the diagnosis of autoimmune virus should be viewed with caution.

Copper fractionation by SEC-HPLC and ETAAS: study of breast milk and infant formulae whey used in lactation of full-term newborn infants

This method will allow the determination of bound copper to low relative molecular mass compounds in milk. The milk whey obtained by ultracentrifugation was submitted to fractionation by size exclusion chromatography (SEC) on a TSK-Gel2000 (Toso Haas) column with a mobile phase of 0.2 M NH4NO3 + NH3, pH 6.7. Fractions of effluent corresponding to the protein peaks were collected and the copper content was determined by ETAAS. The method was sensitive (LOD 0.4 microgram l-1 and LOQ 1.5 micrograms l-1 in the fraction; LOQ 7.5-22.5 micrograms l-1 referred to the milk sample and depended on fraction volume) and precise (RSD +/- 10%). Media sample recoveries from the column were 101.2%. Cu was predominantly present in fractions corresponding to relative molecular mass 76 and 15 kDa of breast milk while copper was mostly found in fractions corresponding to 14 and 38 kDa of cow's milk-based infant formulae; moreover, copper was eluted in the relative molecular mass region < 6 kDa.

[Collagenous colitis: an entity with diverse therapeutic options]

Collagenous colitis is a disorder which has been diagnosed with increasing frequency in the last few years, probably due to the routine obtention of colon biopsy specimens in the study of patients with chronic diarrhoea. Good responses have been reported with a number of therapies, although only a scarce number of clinical trials have been performed, partly because of the small number of patients studied. Two cases of collagenous colitis with different therapeutic approaches are here reported. All medical therapy options for this interesting disorder are reviewed.

[Idiopathic chronic pancreatitis (with diffuse stenosis of Wirsung's duct) in ulcerative colitis]

We describe a case of chronic idiopathic pancreatitis associated with ulcerative colitis. Pancreatitis is a rare extra-intestinal manifestations of inflammatory bowel disease. Chronic idiopathic pancreatitis associated with ulcerative colitis are usually painless, without calcification, with stricture of the main pancreatic duct and with severe exocrine pancreatic insufficiency.