Determination of resistance status to amitraz in the cattle tick Rhipicephalus (Boophilus) microplus from Luzon, Philippines, through bioassay and molecular analysis.

Tick infestations and tick-borne diseases are among the leading causes of economic losses in the cattle industry worldwide. Amitraz is one of the most commonly used chemical acaricides against the cattle tick Rhipicephalus (Boophilus) microplus. Resistance to amitraz has been reported in many countries but not in the Philippines. This study aimed to determine whether cattle ticks from provinces in northern and southern Luzon, Philippines, are resistant to amitraz. Engorged or nearly engorged female ticks were collected from 21 farms and allowed to lay eggs to produce larvae. Larval packet test (LPT) was performed using three concentrations of amitraz, as well as a negative control (diluent). Reverse-transcription polymerase chain reaction (RT-PCR) was also performed to amplify a fragment of the octopamine/tyramine receptor gene and was subjected to sequence analysis by multiple nucleotide and amino acid sequence alignments together with reference strain, amitraz-susceptible strain, and amitraz-resistant strain reported in other countries. LPT results suggest the absence of resistance in all of the tested populations. Interestingly, analysis of the octopamine/tyramine receptor amino acid sequence revealed four out of 14 larval pools having substitutions similar to that of the reported amitraz-resistant strains. Although no apparent resistance was observed in this study, prudent use of amitraz should be practiced as the development of resistance is still likely to occur in the future.

Retrieval Analysis of Neck-Stem Coupling in Modular Hip Prostheses.

BACKGROUND: Dual-taper modular stems have suffered from high revision rates caused by adverse local tissue reactions secondary to fretting and corrosion. We compared the fretting and corrosion behavior of a group of modular neck designs to that of a design that had been recalled for risks associated with fretting and corrosion at the modular neck junction. METHODS: We previously analyzed fretting and corrosion on 60 retrieved Rejuvenate modular neck-stem implants. Here we compare those results to results from 26 retrieved implants from 7 other modular neck designs. For the 26 additional cases, histology slides of tissue collected at revision were reviewed and graded for aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). Multivariate analyses were performed to assess differences in fretting and corrosion, adjusting for confounding factors (eg, length of implantation). RESULTS: The Rejuvenate design had higher damage and corrosion scores than the other 7 designs (P < .01). Histologic samples from the recalled design were 20 times more likely to show ALVAL than samples from the other designs (P < .01). Mixed metal couples had higher fretting (P < .01) and corrosion (P = .02) scores than non-mixed metal couples. CONCLUSION: Fretting and corrosion occurred on all modular neck-stem retrievals regardless of design. However, mixed metal couples suffered more corrosion than homogenous couples. This may be due to the lower modulus of the titanium alloy used for the stem, allowing for increased metal transfer and surface damage when loaded against a cobalt alloy modular neck, which in turn could account for the higher ALVAL and corrosion scores. Due to increased corrosion risk with mixed metals and increased neck fracture risk with non-mixed metal stem and necks, we suggest that clinicians avoid implantation of modular neck-stem systems.

5 points on hip resurfacing.

Hip resurfacing has enjoyed a resurgence in popularity as an alternative to total hip replacement (THR) for the treatment of end-stage arthritis in younger, active patients. However, technical difficulties in implant positioning have been realized, as the procedure has been introduced amongst surgeons new to the concept. Furthermore, as the follow-up interval increases beyond the short-term, it is evident that certain issues with the metal-on-metal bearing surface may lead to complications. These 5 points on hip resurfacing are selected to highlight the factors that will help ensure an optimal outcome.

Adoption of hip resurfacing arthroplasty at hospital for special surgery: a cohort study.

BACKGROUND: Hip resurfacing arthroplasty (HRA) is an alternative to traditional total hip replacement (THR) that allows for the preservation of femoral bone. It is a more technically difficult procedure that has led some researchers to report an unsatisfactory learning curve (Berend et al., J Bone Joint Surg Am Suppl 2:89-92, 2011; Mont et al., Clin Orthop Relat Res 465:63-70, 2007). PURPOSE: The purpose of this study was to investigate the adoption of HRA at our institution, examining the clinical results, revision rate, and modes of failure. Additionally, a comparison of three different implant systems was performed. METHODS: A retrospective review of a consecutive series of HRA performed at our institution between the years 2004 and 2009 was carried out. A total of 820 HRA with a minimum of 2 years of follow-up were included in the study. The majority of included patients were males (70%), with osteoarthritis (92%). The average age was 49.8 years, and the mean BMI was 27.5 kg/m(2). RESULTS: The average Harris hip score improved from 61 to 96.5 postoperatively. Thirteen revisions (1.6%) were performed for femoral neck fracture, femoral head osteonecrosis, acetabular loosening, metal reactivity/metallosis, and metal allergy. The overall Kaplan-Meier survival curve with revision surgery as an endpoint showed 98.5% survival at 5 years. There were no observable differences in clinical scores or revision rates between the different implant systems. CONCLUSIONS: HRA can be successfully adopted with a low complication rate, given careful patient selection, specialized surgical training, and use of good implant design.

Metal-on-metal surface replacement: a triumph of hope over reason: opposes.

Hip resurfacing has been performed for over a decade but still raises controversy as an alternative to traditional total hip arthroplasty (THA). Concerns exist about the potential complications of hip resurfacing, including femoral neck fracture and osteonecrosis of the femoral head. Recently, attention has been given to the metal-on-metal bearing of hip resurfacing with regard to production of metal ions, possible tissue necrosis, and rare instances of metal hypersensitivity. Given the success of the gold-standard THA, it is understandable why some surgeons believe metal-on-metal surface replacement to be "a triumph of hope over reason." However, this article opposes that viewpoint, demonstrating that data exist to justify the practice of preserving bone in younger patients. Hip resurfacing can maintain femoral bone without the expense of removing additional acetabular bone by using modern implants with incremental sizing. Furthermore, many of the problems cited with the bearing couple (such as excess metal production) have been due to poor implant designs, which have now been removed from the market. Finally, we now realize that the metal-on-metal articulation is more sensitive to malposition; thus, good surgical technique and experience can solve many of the problems that have been cited in the past. National registry results confirm that in a select population, hip resurfacing performs comparably to THA, while fulfilling the goal of bone preservation.

Stiffness after TKR: how to avoid repeat surgery.

Stiffness after total knee replacement (TKR) is a frustrating complication that has many possible causes. Although the definition of stiffness has changed over the years, most would agree that flexion <75° and a 15° lack of extension constitutes stiffness. The management of this potentially unsatisfying situation begins preoperatively with guidance of the patient's expectations; it is well-known that preoperative stiffness is strongly correlated with postoperative lack of motion. At the time of surgery, osteophytes must be removed and the components properly sized and aligned and rotated. Soft tissue balancing must be attained in both the flexion/extension and varus/valgus planes. One must avoid overstuffing the tibiofemoral and/or patellofemoral compartments with an inadequate bone resection. Despite these surgical measures and adequate pain control and rehabilitation, certain patients will continue to frustrate our best efforts. These patients likely have a biological predisposition for formation of scar tissue. Other potential causes for the stiff TKR include complex regional pain syndrome or joint infection. Close follow-up of a patient's progress is crucial for the success in return of range of motion. Should motion plateau early in the recovery phase, the patient should be evaluated for manipulation under anesthesia. The results of reoperations for a stiff TKR are variable due to the multiple etiologies. A clear cause of stiffness such as component malposition, malrotation, or overstuffing of the joint has a greater chance of regaining motion than arthrofibrosis without a clear cause. Although surgical treatment with open arthrolysis, isolated component, or complete revision can be used to improve TKR motion, results have been variable and additional procedures are often necessary.

Comparison of bone removed during total hip arthroplasty with a resurfacing or conventional femoral component: a cadaveric study.

We sought to examine the amount of bone removed during total hip arthroplasty with a resurfacing femoral component, compared to with a conventional, stemmed femoral component, by using 6 male and 4 female cadaveric pelves with attached bilateral proximal femora. Using randomized assignment and order, a total hip arthroplasty with a resurfacing femoral implant was performed on one side, and total hip arthroplasty with a cementless, stemmed femoral implant was performed on the contralateral side. The relationship between native femoral head diameter and the implanted acetabular socket was on average within 2 mm for both procedures. No significant difference was observed in the amount of acetabular bone removed (9.8 g for hip resurfacing vs 8.8 g). However, a resurfacing component resulted in approximated 3 x less bone removal from the femur (25.8 g vs 75.1 g). This study shows that the preservation of femoral bone with a resurfacing femoral component does not result in an increased removal of acetabular bone when compared to the use of a conventional, stemmed femoral component.

Clinical development of metformin extended-release tablets for type 2 diabetes: an overview.

Glumetz (Depomed, Inc., Menlo Park, CA, USA) is a recently approved gastric retentive extended-release formulation of metformin (M-ER) that provides effective, sustained and well-tolerated glycemic control with once daily administration. Pharmacokinetic studies have demonstrated a similar bioavailability of M-ER administered once daily to immediate-release metformin given twice daily. In addition, M-ER has demonstrated a nearly linear dose proportionality with a relative bioavailability of highest dose to lowest dose of 80%, whereas with immediate-release metformin the relative bioavailability of the highest dose to the lowest dose is only 58%. M-ER demonstrated a positive food effect and should be administered with a meal, preferably the evening meal. Because metformin is only eliminated through renal mechanisms, the use of M-ER, as is the case with other formulations, is contraindicated in patients with renal impairment. Administration of M-ER with sulfonylureas (SUs) had no effect on the pharmacokinetics of metformin. In controlled clinical trials M-ER demonstrated efficacy for 24 weeks as a monotherapy or in combination with SU. Additionally, glycemic control was maintained for an extra 24 weeks in an open-label monotherapy extension study of M-ER. M-ER was well tolerated in all studies.

Influence of forest machine function on operator exposure to whole-body vibration in a cut-to-length timber harvester.

The influence of machine function (tree felling and processing, and machine movement over the terrain) on operator exposure to whole-body vibration in a cut-to-length (CTL) timber harvester was evaluated. Vibrations were measured on the seat and the cabin chassis in three orthogonal (x, y, z) axes for the tree felling and processing, and during motion on a test track. It was found that the level of vibration transmitted to the operator during felling and processing was mainly affected by the tree size (diameter). For tree diameter at breast height (dbh) range of 0.25-0.35 m that was investigated, the vertical (z-axis) vibration component during processing increased by up to 300%, and increased by 50% during felling. However, the associated vibration levels were not sufficient to pose any serious health risks to the operator for an exposure limit of 8 h. Vibration at the operator seat and cabin chassis was predominant in the lateral (y-axis) and vertical (z-axis) respectively, during vehicle motion over the standard test track. Vibration peaks of approximately 0.20 and 0.17 ms(-2) occurred at 5 and 3.2 Hz respectively.

Influence of tyre inflation pressure on whole-body vibrations transmitted to the operator in a cut-to-length timber harvester.

The influence of tyre inflation pressure on whole-body vibrations transmitted to the operator during the movement of a cut-to-length timber harvester was evaluated. Vibration measurements were taken in three orthogonal (x, y, z) axes at tyre pressure settings of 138, 345 and 414 kPa. Vibration was predominant in the vertical (z) direction with the peak rms acceleration value for the operator seat (0.281 ms(-2)) occurring at approximately 3.2 Hz. The corresponding peak value for the operator cabin chassis was 0.425 m s(-2) at 4 Hz. At 414 kPa, there was potential health risk on the operator for exposures above 8h duration. The vibration total values recorded for the operator seat at the maximum tyre inflation pressure setting were classed as "fairly uncomfortable" (ISO standard 2631-1), and vertical seat vibration transmissibility was highest between 4 and 8 Hz at the 345 kPa tyre pressure setting. The recorded values of WBV were significantly reduced by a reduction in tyre inflation pressure which may therefore be used to moderate the magnitude of WBV on wheeled timber harvesters.

Evolving metabolic changes during the first postoperative year after subthalamotomy.

OBJECT: Short-term benefit from unilateral subthalamotomy for advanced Parkinson disease (PD) is associated with metabolic alterations in key targets of subthalamic nucleus (STN) and globus pallidus (GP) output. In this study positron emission tomography (PET) scanning was used to assess these changes and their relation to long-term benefits of subthalamotomy. METHODS: To determine whether the early postoperative changes persisted at longer-term follow up, the authors assessed six patients with advanced PD by using [18F]fluorodeoxyglucose-PET at 3 and 12 months postsurgery. The authors compared each of the postoperative images with baseline studies, and assessed interval changes between the short- and long-term follow-up scans. Clinical improvement at 3 and 12 months was associated with sustained metabolic decreases in the midbrain GP internus (GPi), thalamus, and pons of the lesioned side (p < 0.01). The activity of a PD-related multiregional brain network, which correlated with bradykinesia and rigidity, was reduced at both postoperative time points (p < 0.05). Comparisons of 3- and 12-month images revealed a relative metabolic increase in the GP externus (GPe) (p < 0.001), which was associated with worsening gait, postural stability, and tremor at long-term follow up. CONCLUSIONS: These findings indicate that subthalamotomy may have differential effects on each of the functional pathways that mediate parkinsonian symptomatology. Sustained relief of akinesia and rigidity is associated with suppression of a pathological network involving the GPi and its output. In contrast, the recurrence of tremor may relate to changes in the function of an STN-GPe oscillatory network.

The Stark II reality.

The long awaited final regulations in Phase I of a two-phase rulemaking process under the Stark II law were published on January 4, 2001. The Phase I final rules govern interpretation of the Stark law as it is applied to referrals by a physician for designated categories of health services to entities in which the referring physician has a financial interest. These new regulations are of particular concern to specialists, such as orthopaedic surgeons, whose practices are oriented to ancillary services that are considered designated health services, such as radiology, physical therapy and durable medical equipment, and where the availability of clear guidance is essential to ensure that medically necessary care is provided in a manner that complies with law. However, rather than the "brightline" guidance that the healthcare community sought, the new regulations create uncertainty in areas that had not existed before. The new regulations require physicians to evaluate the full range of their business and professional relationships to avoid the risk of nonpayment of claims, civil money penalties, or program exclusion after the effective date of the new regulations.

Type II achondrogenesis-hypochondrogenesis: morphologic and immunohistopathologic studies.

A 32-wk-gestation female with type II achondrogenesis-hypochondrogenesis has been studied. The clinical features were typical, and radiographs revealed short ribs, hypoplastic ilia, absence of ossification of sacrum, pubis, ischia, tali, calcanei, and many vertebral bodies; the long bones were short with mild metaphyseal flaring. The femoral cylinder index was 6.3. Comparison with previous cases placed the patient toward the mild end of the achondrogenesis-hypochondrogenesis spectrum (Whitley-Gorlin prototype IV). Light microscopy revealed hypercellular cartilage with decreased matrix traversed by numerous fibrous vascular canals. The growth plate was markedly abnormal. Ultrastructural studies revealed prominently dilated rough endoplasmic reticulum containing a fine granular material with occasional fibrils in all chondrocytes. Immunohistologic studies indicated irregular large areas of cartilage matrix staining with monoclonal antibody to human type III collagen. The relative intensity of matrix staining for type II collagen appeared diminished. More striking, however, were intense focal accumulations of type II collagen within small rounded perinuclear structures of most chondrocytes but not other cell types. These results strongly suggest intracellular retention of type II collagen within vacuolar structures, probably within the dilated rough endoplasmic reticulum observed in all chondrocytes by electron microscopy (EM), and imply the presence of an abnormal, poorly secreted type II collagen molecule. Biochemical studies (see companion paper) suggest that this patient had a new dominant lethal disorder caused by a structural abnormality of type II collagen.

Intravascular papillary endothelial hyperplasia. A benign lesion mimicking angiosarcoma.

Observations were made of three cases of intravascular papillary endothelial hyperplasia (IPEH). Lesions of IPEH usually occur on the head and neck area as a subcutaneous red or blue nodule. This papillary proliferation of endothelial and stromal tissue occurs de novo in organizing venous thrombi or in preexisting hemangiomas or phlebectasias. An adequate understanding of this benign vascular disorder is important, since the lesion may be clinically and histologically mistaken for low grade angiosarcoma.

Therapeutic abortion. Attitudes and practices of California physicians.

A questionnaire about attitudes and practices regarding therapeutic abortion was sent to 943 diplomates of the American Board of Obstetrics and Gynecology listed in California. In the 748 replies received, certain disparities between the views and practices of the specialists on the one hand and current California statutes on the other were noted. The responses to the questions strongly suggested that current California laws governing the performance of therapeutic abortion are in need of modernization and liberalization if they are to accord with the views and practices of California obstetrician-gynecologists.