Cadmium in forest ecosystems around lead smelters in Missouri.

The development of Missouri's new lead belt within the past decase has provided an excellent opportunity to study the dissemination and effects of heavy metals in a deciduous forest ecosystem. Primary lead smelters within the new lead belt have been identified as potential sources of cadmium as well as lead, zinc, and copper. Sintering and blast furnace operations tend to produce significant quantities of small particulates highly enriched in cadmium and other heavy metals. At one smelter, samples of stack particulate emissions indicate that as ms accompanied by 0.44 lb zinc, 4.66 lb lead, and 0.01 lb copper/hr. These point-source emissions, as well as a number of other sources of fugitive (wind blown) and waterborne emissions contribute to a significant deposition of cadmium in the surrounding forest and stream beds. Mobilization of vagrant heavy metals may be significantly increased by contact of baghouse dusts or scrubber slurries with acidic effluents emanating from acid plants designed to produce H2SO4 as a smelter by-product. Two separate drainage forks within the Crooked Creek watershed permit some comparisons of the relative contributions of cadmium by air-borne versus water-borne contaminants. Cadmium and other heavy metals have been found to accumulate in the forest litter and partially decomposed litter along stream beds. Greater solubility, lower levels of complexation with organic ligands in the litter, and greater overall mobility of cadmium compared with lead, zinc, and copper result in appreciable contributions of dissolved cadmium to the watershed runoff. The present paper attempts to define the principle sources and current levels of heavy metal contamination and summarizes the efforts undertaken by the industry to curtail the problem

The Distribution Of Chlorine And Iodine In Soil In The Vicinity Of Lead Mining And Smelting Operations, Bixby Area, S.E. Missouri, U.S.A.

Iodine and Cl are enriched in soils in the vicinity of the Magmont and Buick lead mines near Bixby, southeastern Missouri. The enrichments, up to 5.6 ppm I and 305 ppm Cl, are against regional background of 1.26 ppm I and 41 ppm Cl. The area of highest I and Cl is thought to reflect a zone of base metal sulphide mineralization occurring about 400 m below the surface. Iodine and Cl are also enriched in soils immediately adjacent to a tailings pond, hence these elements would appear to be leached from this source. A zone of enhanced I values (up to 2.65 ppm I) to the north of a lead smelter is superimposed on a much larger zone of lead enrichment (up to 12,000 ppm Pb) and is thought to represent I released from sulphide ores on smelting. © 1988

Magnetic systems for cancer immunotherapy

Immunotherapy is a rapidly developing area of cancer treatment due to its higher specificity and potential for greater efficacy than traditional therapies. Immune cell modulation through the administration of drugs, proteins, and cells can enhance antitumoral responses through pathways that may be otherwise inhibited in the presence of immunosuppressive tumors. Magnetic systems offer several advantages for improving the performance of immunotherapies, including increased spatiotemporal control over transport, release, and dosing of immunomodulatory drugs within the body, resulting in reduced off-target effects and improved efficacy. Compared to alternative methods for stimulating drug release such as light and pH, magnetic systems enable several distinct methods for programming immune responses. First, we discuss how magnetic hyperthermia can stimulate immune cells and trigger thermoresponsive drug release. Second, we summarize how magnetically targeted delivery of drug carriers can increase the accumulation of drugs in target sites. Third, we review how biomaterials can undergo magnetically driven structural changes to enable remote release of encapsulated drugs. Fourth, we describe the use of magnetic particles for targeted interactions with cellular receptors for promoting antitumor activity. Finally, we discuss translational considerations of these systems, such as toxicity, clinical compatibility, and future opportunities for improving cancer treatment. &nbsp;</p

Stem subsidence of polished and rough double-taper stems: In vitro mechanical effects on the cement-bone interface

Background and purpose Many clinical reports have indicated that polished hip stems show better clinical results than rough stems of the same geometry. It is still unknown, however, what the mechanical effects are of different surface finishes on the cement at the cement-bone interface. We compared mechanical effects in an in vitro cemented hip arthroplasty model

Effectiveness of computer-navigated minimally invasive total hip surgery compared to conventional total hip arthroplasty: design of a randomized controlled trial

BACKGROUND: Moderate to severe osteoarthrosis is the most common indication for Total Hip Arthroplasty (THA). Minimally Invasive Total Hip Surgery (MIS) and computer-navigated surgery were introduced several years ago. However, the literature lacks well-designed studies that provide evidence of superiority of computer-navigated MIS over a conventional THA technique. Hence, the purpose of this study is to compare (cost)effectiveness of computer-navigated MIS with a conventional technique for THA. It is our hypothesis that computer-navigated MIS will lead to a quicker recovery during the early postoperative period (3 months), and to an outcome at least as good 6 months postoperatively. We also hypothesize that computer-navigated MIS leads to fewer perioperative complications and better prosthesis positioning. Furthermore, cost advantages of computer-navigated MIS over conventional THA technique are expected. METHODS/DESIGN: A cluster randomized controlled trial will be executed. Patients between the ages of 18 and 75 admitted for primary cementless unilateral THA will be included. Patients will be stratified using the Charnley classification. They will be randomly allocated to have computer-navigated MIS or conventional THA technique. Measurements take place preoperatively, perioperatively, and 6 weeks and 3 and 6 months postoperatively. Degree of limping (gait analysis), self-reported functional status and health-related quality of life (questionnaires) will be assessed preoperatively as well as postoperatively. Perioperative complications will be registered. Radiographic evaluation of prosthesis positioning will take place 6 weeks postoperatively. An evaluation of costs within and outside the healthcare sector will focus on differences in costs between computer-navigated MIS and conventional THA technique. DISCUSSION: Based on studies performed so far, few objective data quantifying the risks and benefits of computer-navigated MIS are available. Therefore, this study has been designed to compare (cost) effectiveness of computer-navigated MIS with a conventional technique for THA. The results of this trial will be presented as soon as they become available

Minimal stress shielding with a Mallory-Head titanium femoral stem with proximal porous coating in total hip arthroplasty

<p>Abstract</p> <p>Background</p> <p>As longevity of cementless femoral components enters the third decade, concerns arise with long-term effects of fixation mode on femoral bone morphology. We examined the long-term consequences on femoral remodeling following total hip arthroplasty with a porous plasma-sprayed tapered titanium stem.</p> <p>Methods</p> <p>Clinical data and radiographs were reviewed from a single center for 97 randomly selected cases implanted with the Mallory-Head Porous femoral component during primary total hip arthroplasty. Measurements were taken from preoperative and long-term follow-up radiographs averaging 14 years postoperative. Average changes in the proximal, middle and diaphyseal zones were determined.</p> <p>Results</p> <p>On anteroposterior radiographs, the proximal cortical thickness was unchanged medially and the lateral zone increased 1.3%. Middle cortical thickness increased 4.3% medially and 1.2% laterally. Distal cortical thickness increased 9.6% medially and 1.9% laterally. Using the anteroposterior radiographs, canal fill at 100 mm did not correlate with bony changes at any level (Spearman's rank correlation coefficient of -0.18, 0.05, and 0.00; p value = 0.09, 0.67, 0.97). On lateral radiographs, the proximal cortical thickness increased 1.5% medially and 0.98% laterally. Middle cortical thickness increased 2.4% medially and 1.3% laterally. Distal cortical thickness increased 3.5% medially and 2.1% laterally. From lateral radiographs, canal fill at 100 mm correlated with bony hypertrophy at the proximal, mid-level, and distal femur (Spearman's rank correlation coefficient of 0.85, 0.33, and 0.28, respectively; p value = 0.001, 0.016, and 0.01, respectively).</p> <p>Conclusion</p> <p>Stress shielding is minimized with the Mallory-Head titanium tapered femoral stem with circumferential proximal plasma-sprayed coating in well-fixed and well-functioning total hip arthroplasty. Additionally, the majority of femora demonstrated increased cortical thickness in all zones around the stem prosthesis. Level of Evidence: Therapeutic Level III.</p

Electromagnetic Field Effect or Simply Stress? Effects of UMTS Exposure on Hippocampal Longterm Plasticity in the Context of Procedure Related Hormone Release

Harmful effects of electromagnetic fields (EMF) on cognitive and behavioural features of humans and rodents have been controversially discussed and raised persistent concern about adverse effects of EMF on general brain functions. In the present study we applied radio-frequency (RF) signals of the Universal Mobile Telecommunications System (UMTS) to full brain exposed male Wistar rats in order to elaborate putative influences on stress hormone release (corticosteron; CORT and adrenocorticotropic hormone; ACTH) and on hippocampal derived synaptic long-term plasticity (LTP) and depression (LTD) as electrophysiological hallmarks for memory storage and memory consolidation. Exposure was computer controlled providing blind conditions. Nominal brain-averaged specific absorption rates (SAR) as a measure of applied mass-related dissipated RF power were 0, 2, and 10 W/kg over a period of 120 min. Comparison of cage exposed animals revealed, regardless of EMF exposure, significantly increased CORT and ACTH levels which corresponded with generally decreased field potential slopes and amplitudes in hippocampal LTP and LTD. Animals following SAR exposure of 2 W/kg (averaged over the whole brain of 2.3 g tissue mass) did not differ from the sham-exposed group in LTP and LTD experiments. In contrast, a significant reduction in LTP and LTD was observed at the high power rate of SAR (10 W/kg). The results demonstrate that a rate of 2 W/kg displays no adverse impact on LTP and LTD, while 10 W/kg leads to significant effects on the electrophysiological parameters, which can be clearly distinguished from the stress derived background. Our findings suggest that UMTS exposure with SAR in the range of 2 W/kg is not harmful to critical markers for memory storage and memory consolidation, however, an influence of UMTS at high energy absorption rates (10 W/kg) cannot be excluded

Navigated cup implantation in hip arthroplasty: A meta-analysis

Background and purpose Many studies have suggested that navigation-based implantation can improve cup positioning in total hip arthroplasty (THA). We conducted a systematic review and meta-analysis to compile the best available evidence, and to overcome potential shortcomings because of small sample sizes in individual studies