Open-air sprays for capturing and controlling airborne float coal dust on longwall faces.

Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening.

Characterization of airborne float coal dust emitted during continuous mining, longwall mining and belt transport.

Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof and ribs of mine airways. If deposited, float dust is re-entrained during a methane explosion. Without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting, which is the adding of inert material to airway surfaces, is the main control technique currently used by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, the Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section and a coal-handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation, and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8.

Sampling and analysis method for measuring airborne coal dust mass in mixtures with limestone (rock) dust.

Airborne coal dust mass measurements in underground bituminous coal mines can be challenged by the presence of airborne limestone dust, which is an incombustible dust applied to prevent the propagation of dust explosions. To accurately measure the coal portion of this mixed airborne dust, the National Institute for Occupational Safety and Health (NIOSH) developed a sampling and analysis protocol that used a stainless steel cassette adapted with an isokinetic inlet and the low temperature ashing (LTA) analytical method. The Mine Safety and Health Administration (MSHA) routinely utilizes this LTA method to quantify the incombustible content of bulk dust samples collected from the roof, floor, and ribs of mining entries. The use of the stainless steel cassette with isokinetic inlet allowed NIOSH to adopt the LTA method for the analysis of airborne dust samples. Mixtures of known coal and limestone dust masses were prepared in the laboratory, loaded into the stainless steel cassettes, and analyzed to assess the accuracy of this method. Coal dust mass measurements differed from predicted values by an average of 0.5%, 0.2%, and 0.1% for samples containing 20%, 91%, and 95% limestone dust, respectively. The ability of this method to accurately quantify the laboratory samples confirmed the validity of this method and allowed NIOSH to successfully measure the coal fraction of airborne dust samples collected in an underground coal mine.

Recurrence of type 1 diabetes after simultaneous pancreas-kidney transplantation in the absence of GAD and IA-2 autoantibodies.

We report herein the patterns of type 1 diabetes recurrence in a simultaneous pancreas-kidney transplant (SPK) recipient, in the absence of rejection. A 38-year-old female underwent SPK for end-stage nephropathy secondary to type 1 diabetes. Fasting blood glucose, HbA1c, fructosamine, C-peptide and autoantibodies (GAD-65, IA-2) were monitored throughout follow-up. At 3.5 years post-SPK, HbA1c and fructosamine increased sharply, indicating loss of perfect metabolic control, despite C-peptide levels in the normal-high range. Exogenous insulin was restarted 4 months later. C-peptide levels abruptly fell and became undetectable at 5.5 years. Autoantibody levels, which were undetectable at the time of SPK, never converted to positivity. Pancreas retranspantation was performed at 6 years. The failed pancreas graft had a normal macroscopic appearance. On histology, there were no signs of cellular or humoral rejection in the kidney or pancreas. A selective peri-islet lymphocytic infiltrate was observed, together with near-total destruction of ß cells. At 2.5 years post retransplantation, pancreatic graft function is perfect. This observation indicates unequivocally that pancreas graft can be lost to recurrence of type 1 diabetes in the absence of rejection. GAD-65 and IA-2 autoantibodies are not reliable markers of autoimmunity recurrence.

Effect of the environment on wear ranking and corrosion of biomedical CoCrMo alloys.

The corrosion behaviour and the wear ranking of biomedical high carbon (HC) and low carbon (LC) CoCrMo alloys sliding against an alumina ball in four different simulated body fluids [NaCl and phosphate buffered solutions (PBS) with and without albumin] has been analyzed by tribocorrosion and electrochemical techniques. The effects of alloy and of albumin on corrosion depend on the base electrolyte: differences between LC and HC alloy were only observed in NaCl solutions but not in PBS. Albumin increased significantly corrosion of both alloys in PBS solutions while its effect in NaCl was smaller. The wear ranking of the HC and LC alloys also depends on the environment. In the present study, HC CoCrMo alloy had lower wear resistance in NaCl and PBS + albumin than the LC alloy, while no differences between both alloys were found in the other solutions. This was attributed to surface chemical effects affecting third body behaviour.

Cutaneous melanoma with metastasis in a cynomolgus monkey (Macaca fascicularis).

BACKGROUND: A 3.3-year-old-male cynomolgus macaque (Macaca fascicularis) showed a focally extensive soft, dark, discoid dermal mass, 0.5 cm in diameter, on the dorsal surface of the right hind foot, over the fourth and fifth metatarsal bones. METHODS AND RESULTS Microscopic examination revealed a cutaneous melanoma with local lymphatic invasion, characterized by neoplastic melanocytes within the subcapsular sinus of popliteal and inguinal lymph nodes. The diagnosis was confirmed by immunohistochemistry and transmission electron microscopy. CONCLUSIONS: To our knowledge, this is the first documented case of melanoma in a cynomolgus monkey.

Clinical magnetic resonance imaging of pancreatic islet grafts after iron nanoparticle labeling.

There is a crucial need for noninvasive assessment tools after cell transplantation. This study investigates whether a magnetic resonance imaging (MRI) strategy could be clinically applied to islet transplantation. The purest fractions of seven human islet preparations were labeled with superparamagnetic iron oxide particles (SPIO, 280 microg/mL) and transplanted into four patients with type 1 diabetes. MRI studies (T2*) were performed prior to and at various time points after transplantation. Viability and in vitro and in vivo functions of labeled islets were similar to those of control islets. All patients could stop insulin after transplantation. The first patient had diffuse hypointense images on her baseline liver MRI, typical for spontaneous high iron content, and transplant-related modifications could not be observed. The other three patients had normal intensity on pretransplant images, and iron-loaded islets could be identified after transplantation as hypointense spots within the liver. In one of them, i.v. iron therapy prevented subsequent visualization of the spots because of diffuse hypointense liver background. Altogether, this study demonstrates the feasibility and safety of MRI-based islet graft monitoring in clinical practice. Iron overload (spontaneous or induced) represents the major obstacle to the technique.

Methods for functionalization of microsized polystyrene beads with titania nanoparticles for cathodic electrophoretic deposition.

Functionalization of colloidal particles based on the use of polyelectrolytes and heterocoagulation was combined with electrophoretic deposition (EPD), with the aim of depositing titania-polystyrene (TiO(2)-PS) composite particles on Ti6Al4V substrates. The composite particles were obtained by heterocoagulation of TiO(2) nanoparticles on the surface of monosized polystyrene beads of 4.6 microm in diameter. Two alternative methods were developed for the preparation of the TiO(2)-PS suspensions in organic fluids for cathodic electrodeposition. The first method was carried out in alkaline aqueous medium with the use of polyelectrolytes and intermediate control measurements of zeta potential, conductivity, and pH; the second one was carried out directly in the organic solvent used for EPD, typically isopropanol. Examples of deposits obtained by EPD in both suspensions and a comparative analysis between the two methods are presented.

An analysis of the in vivo deterioration of Co-Cr-Mo implants through wear and corrosion.

The degradation of Co-Cr-Mo ASTM F75-92 hip implants after a harvesting period of 81 months in sheep was investigated. Hip prostheses and tissue samples were obtained from a medical study involving total hip arthroplasty of the cemented type in 12 sheep. Upon euthanasia, the explants were retrieved for analyses of the surfaces and evidence of degradation, while tissue samples from the interface regions were harvested for chemical analysis and evidence of Co, Cr, and Mo contents. Clear evidence of wear and corrosion was detected. Results also indicated that the modes of metal transport through the poly(methyl methacrylate) bone cement play an important role as the surface degradation mechanisms of the metal. The results are being discussed in terms of electrochemical and triboelectrochemical behaviour of the Co-Cr-Mo alloy.

In-situ Generated Tribomaterial in Metal/Metal Contacts: current understanding and future implications for implants.

Artificial hip joints operate in aqueous biofluids that are highly reactive towards metallic surfaces. The reactivity at the metal interface is enhanced by mechanical interaction due to friction, which can change the near-surface structure of the metal and surface chemistry. There are now several reports in the literature about the in-situ generation of reaction films and tribo-metallurgical transformations on metal-on-metal hip joints. This paper summarizes current knowledge and provides a mechanistic interpretation of the surface chemical and metallurgical phenomena. Basic concepts of corrosion and wear are illustrated and used to interpret available literature on in-vitro and in-vivo studies of metal-on-metal hip joints. Based on this review, three forms of tribomaterial, characterized by different combinations of oxide films and organic layers, can be determined. It is shown that the generation of these tribofilms can be related to specific electrochemical and mechanical phenomena in the metal interface. It is suggested that the generation of this surface reaction layer constitutes a way to minimize (mechanical) wear of MoM hip implants.

Impact of a sirolimus/tacrolimus-based immunosuppressive regimen on kidney function after islet transplantation.

AIM: Islet transplantation is gaining recognition as a therapeutic option for selected diabetic patients. The immunosuppressive regimen based on sirolimus/low-dose tacrolimus is considered a major breakthrough that allowed considerable improvement in graft survival. A high incidence of side effects associated with such a regimen has been reported in the literature, but this immunosuppressive protocol is generally considered safe or even protective to the kidney. Herein, we analyze the impact of the sirolimus/low-dose tacrolimus-based protocol on kidney function. PATIENTS AND METHODS: Five islet-after-kidney and 5 islet-transplant-alone patients were enrolled and followed up. Renal function was assessed by the periodic measurement of serum creatinine and by the presence of albuminuria. Metabolic control markers and graft function were followed, as well as immunosuppressive whole blood trough levels. RESULTS: Kidney function significantly decreased in 6 of 10 patients. Neither metabolic markers nor immunosuppressive drugs levels were significantly associated with the decreased kidney function. CONCLUSION: Although a specific etiology was not identified, subsets of patients presented a higher risk for decrease of kidney function. The presence of low creatinine clearance, albuminuria, and long-established kidney graft were associated with poorer outcomes.

Effect of HLA matching in simultaneous pancreas-kidney transplantation.

UNLABELLED: Simultaneous pancreas-kidney (SPK) transplantation has become the therapy of choice for type 1 diabetic patients with end-stage renal disease. The current analysis examined the impact of HLA matching on graft outcome following SPK transplantation. The study population was obtained from patients enrolled in the Euro-SPK 001 study. PATIENTS AND METHODS: The effect of HLA matching on graft function and survival was assessed in 180 SPK recipients in whom complete donor-recipient HLA data were available. A group of 45 patients with 0 to 3 HLA mismatches (MM) was compared to 135 patients with 4 to 6 MM. RESULTS: There were no differences in 3-year kidney, pancreas, or patient survival rates between the 0 to 3 and 4 to 6 MM groups. Biological parameters of kidney and pancreas graft function were similar in both groups. Significantly more patients with 0 to 3 MM (66%) were rejection free at 3 years than those with 4 to 6 MM (41%; P = .003). The relative risk of acute rejection was 2.6 times higher among patients with 4 to 6 MM than among those with 0 to 3 MM. In conclusion, there was no evidence that HLA matching was associated with improved kidney or pancreas survival. However, a higher rate of acute rejection was observed with poor HLA matches, which may impact long-term survival.

Adverse tissue reaction to corrosion at the neck-stem junction after modular primary total hip arthroplasty.

Complications related to the neck-stem junction of modular stems used for total hip arthroplasty (THA) are generating increasing concern. A 74-year-old male had increasing pain and a cutaneous reaction around the scar 1 year after THA with a modular neck-stem. Imaging revealed osteolysis of the calcar and a pseudo-tumour adjacent to the neck-stem junction. Serum cobalt levels were elevated. Revision surgery to exchange the stem and liner and to resect the pseudo-tumour was performed. Analysis of the stem by scanning electron microscopy and by energy dispersive X-ray and white light interferometry showed fretting corrosion at the neck-stem junction contrasting with minimal changes at the head-neck junction. Thus, despite dry assembly of the neck and stem on the back table at primary THA, full neck-stem contact was not achieved, and the resulting micromotion at the interface led to fretting corrosion. This case highlights the mechanism of fretting corrosion at the neck-stem interface responsible for adverse local tissue reactions. Clinical and radiological follow-up is mandatory in patients with dual-modular stems.

In vivo electrochemical corrosion study of a CoCrMo biomedical alloy in human synovial fluids.

The present study was initiated with the aim to assess the in vivo electrochemical corrosion behaviour of CoCrMo biomedical alloys in human synovial fluids in an attempt to identify possible patient or pathology specific effects. For this, electrochemical measurements (open circuit potential OCP, polarization resistance Rp, potentiodynamic polarization curves, electrochemical impedance spectroscopy EIS) were carried out on fluids extracted from patients with different articular pathologies and prosthesis revisions. Those electrochemical measurements could be carried out with outstanding precision and signal stability. The results show that the corrosion behaviour of CoCrMo alloy in synovial fluids not only depends on material reactivity but also on the specific reactions of synovial fluid components, most likely involving reactive oxygen species. In some patients the latter were found to determine the whole cathodic and anodic electrochemical response. Depending on patients, corrosion rates varied significantly between 50 and 750 mg dm(-2)year(-1).

Successful implementation of guidelines for encouraging the use of beta blockers in patients after acute myocardial infarction.

PURPOSE: To assess whether implementation of guidelines increases the prescription of drugs, particularly beta blockers, recommended for secondary prevention after acute myocardial infarction. SUBJECTS AND METHODS: Prescription patterns among 355 patients discharged from a public teaching hospital after recovery from myocardial infarction were prospectively monitored in a before-after trial. The implementation strategies included educational interventions (large group meetings), placement of guidelines in patients' records, and bimonthly general reminders sent to physicians. RESULTS: Beta blockers were prescribed in 93 (38%) of 243 survivors of acute myocardial infarction before guideline implementation (12-month control period), as compared with 71 (63%) of 112 patients (P <0.001) after their implementation (6-month period). During the entire study period, the prescription of beta blockers at a neighboring public teaching hospital, used as a comparison, was unchanged. After adjusting for potential confounders, implementation of the guidelines remained significantly associated with prescription of beta blockers at discharge [odds ratio (OR) = 10; 95% confidence interval (CI), 3.2 to 33; P <0.001]. Other independent predictors of prescription of beta blockers were previous coronary artery bypass grafting (OR = 8.7; 95% CI, 2.5 to 31; P = 0.001), hypertension (OR = 2.5; 95% CI, 1.4 to 4.5; P = 0.003), age per 10-year increase (OR = 0.82; 95% CI, 0.67 to 0.99; P = 0.04), secular trend in prescription patterns expressed in months (OR = 0.9; 95% CI, 0.8 to 1.0; P = 0.02), a left ventricular ejection fraction < or = 40% (OR = 0.2; 95% CI, 0.1 to 0.4; P <0.001), the presence of atrioventricular block (OR = 0.1; 95% CI, 0.02 to 0.7; P = 0.02), and concomitant prescription of digoxin (OR = 0.2; 95% CI, 0.05 to 0.8; P = 0.02) or calcium antagonists (OR = 0.06; 95% CI, 0.01 to 0.3; P = 0.001). CONCLUSION: When appropriately developed and implemented by local experts, literature-based guidelines may be effective in modifying use of recommended drugs for secondary prevention of coronary artery disease, such as prescription of beta blockers.

Do physicians modify their prehospital management of patients in response to a public campaign on chest pain?

The goals of this study were to analyze the impact of a public campaign on chest pain on physicians involved in the prehospital care of patients with this symptom, in terms of physician delay, rates of immediate hospitalization, and of transportation by ambulance. Prehospital delays and decisions for all 866 patients with chest pain managed by the community and generalist physicians or by emergency physicians, who presented to the emergency department of a teaching hospital during the 12 months of the campaign, were compared with those of all 749 patients with similar presentations during the 12 months before it. When community and generalist physicians were involved, median (110 minutes) physician delay did not decrease during the campaign, whereas it decreased from 65 to 56 minutes (p <0.003) when emergency physicians were involved. Rates of immediate hospitalization (73%) and of transportation by ambulance (47%) of patients managed by community and generalist physicians were unaffected by the campaign, whereas they increased from 96% and 89%, respectively, to 98% (p = 0.09) and 94% (p <0.02) when emergency physicians were involved. Similar observations were made in patients with confirmed acute myocardial infarction and unstable angina and remained highly significant after adjustment for differences in clinical characteristics. Thus, community and generalist physicians did not significantly modify their prehospital management of patients with chest pain despite a public campaign. To be successful, guidelines on the matter have to be developed with the active participation of these physicians.

Prolonged antinociception following carbon dioxide anesthesia in the laboratory rat.

In the laboratory rat, inhalation (30 s) of high (> 70%) CO2 concentrations resulted in short-term (1-3 min) anesthesia, followed by a prolonged (up to 60 min) mild antinociception. Exposure to 100% CO2 resulted in significant thermal (hot-plate, 52 degrees, and tail-flick) and mechanical (tail-pinch, 886 g force) antinociception. Control animals, placed in the same chamber filled with air, showed no such effects. Rats exposed to 70% CO2 exhibited effects on the hot plate comparable to those seen after inhalation of 100% CO2, indicating that the response is not due to CO2-induced hypoxia. Additionally, recovery from halothane-induced anesthesia of comparable duration did not result in antinociception, confirming that anesthesia alone is not sufficient to produce the effect. Pretreatment with the opiate antagonist naltrexone (0.1-10 mg/kg i.p.) did not diminish the CO2-induced antinociception, suggesting that endogenous opioids are not obligatory in the mechanism of this response. Furthermore, hypophysectomy abolished hot-plate antinociception in animals exposed to 100% CO2 while sham-treated controls exhibited a pattern of hot-plate responses similar to that reported above. Taken together, these findings show that: (1) recovery from CO2-induced anesthesia results in a prolonged mild antinociception, detectable with thermal and mechanical nociceptive tests; and (2) this response may represent a novel from of environmentally induced antinociception, mediated by a non-opiate hormonal substance.

Impact of a public campaign on pre-hospital delay in patients reporting chest pain.

OBJECTIVE: To decrease pre-hospital delay in patients with chest pain. DESIGN: Population based, prospective observational study. SETTING: A province of Switzerland with 380000 inhabitants. SUBJECTS: All 1337 patients who presented with chest pain to the emergency department of the Hôpital Cantonal Universitaire of Geneva during the 12 months of a multimedia public campaign, and the 1140 patients who came with similar symptoms during the 12 months before the campaign started. MAIN OUTCOME MEASURES: Pre-hospital time delay and number of patients admitted to the hospital for acute myocardial infarction (AMI) and unstable angina. RESULTS: Mean pre-hospital delay decreased from 7h 50 min before the campaign to 4 h 54 min during it, and median delay from 180 min to 155 min (P < 0.001). For patients with a final diagnosis of AMI, mean delay decreased from 9 h 10 min to 5 h 10 min and median delay from 195 min to 155 min (P < 0.002). Emergency department visits per week for AMI and unstable angina increased from 11.2 before the campaign to 13.2 during it (P < 0.02), with an increase to 27 (P < 0.01) during the first week of the campaign; visits per week for non-cardiac chest pain increased from 7.6 to 8.1 (P = NS) during the campaign, with an increase to 17 (P < 0.05) during its first week. CONCLUSIONS: Public campaigns may significantly reduce pre-hospital delay in patients with chest pain. Despite transient increases in emergency department visits for non-cardiac chest pain, such campaigns may significantly increase hospital visits for AMI and unstable angina and thus be cost effective.

Characteristics of carbon dioxide-induced antinociception.

This lab previously showed that brief inhalation of high concentrations of CO2 results in a prolonged, moderate antinociception with characteristics of a nonopiate, hormonal mechanism. To further characterize and optimize this response, the effect of a variety of methodological, biological, and stress-related manipulations were studied. No significant differences were found in the CO2-induced response between animals that were tested during different portions of their diurnal cycles, in rats that were unhandled or habituated to nociceptive testing conditions, in male vs. female rats, or in animals of differing weights. Additionally, restraining animals prior to CO2 exposure induced a hot plate antinociceptive response that was not different from the response produced by CO2 alone. In contrast, on the tail flick test, a CO2 -restraint interaction both increased and decreased the response at different times. The present findings show that CO2 antinociception: a) is a reliable phenomenon not altered by a variety of methodological and biological conditions, and b) has characteristics of a novel, stress-mediated antinociceptive response.

Islet autotransplantation for the prevention of surgical diabetes after extended pancreatectomy for the resection of benign tumors of the pancreas.

OBJECTIVE: The objective of this article is to report a single-center experience with islet autotransplantation after extensive pancreatic resection for benign tumors of the pancreas. MATERIALS AND METHODS: Seven patients underwent extensive left pancreatectomy for benign lesions located at the neck of the pancreas. Once an unequivocal diagnosis of a benign nature was ascertained, the rest of the specimen was processed and the unpurified pancreatic digest was infused into the portal vein. The results were compared with those of 8 autotransplantations performed for chronic pancreatitis over the same period. RESULTS: Tumors were 4 cystadenomas, 2 insulinomas and 1 neuroendocrine tumor. Mean islet yields were 275,000 islet equivalents (IEQ) versus 129,000 in chronic pancreatitis (P =.04) or 6700 IEQ/g of tissue versus 1900 (P =.002), resulting in transplantation of 4200 IEQ/kg body weight vs 2150 in chronic pancreatitis (P =.03), respectively at 4-month to 7.5-year follow-up, all patients are alive and 6 of 7 are off insulin. All patients off insulin after at least 1 year currently have a normal IVGTT, with K values ranging between -1.19 and -2.36 (normal < -1.00). All patients, including 1 on insulin, display positive basal and glucagon-stimulated C-peptide levels. CONCLUSIONS: Compared with chronic pancreatitis tissue resected for benign tumors is more likely to achieve good islet yields, and thus insulin independence after autotransplantation. Islet autotransplantation should be considered when extensive pancreatectomy is required for resection of a benign tumor, and only if the benign nature of the lesion is demonstrated unequivocally.