Quantitative measurement of lead in paint by XRF analysis without manual substrate correction

X-ray fluorescence analysis has been used for measurement of lead in paint for more than a decade. The early systems provided a nondestructive alternative technology to laboratory-based technologies, but were somewhat time consuming and often led to inconclusive results. The procedure required manual substrate correction, multiple measurements, operator's discretion in validating a measurement due to interfering elements and laboratory analysis of inconclusive samples. A new instrument, the RMD LPA-1 system, has been developed based on X-ray fluorescence technology that addresses all of the drawbacks to the older systems. This new system uses a carefully designed and controlled geometry and modern microprocessor technology to automatically provide a rapid quantitative measurement of lead in paint with a 95% confidence level. The improved precision and accuracy achieved with this system are due to geometric enhancements and a mathematical approach which incorporates corrections for both random and systematic errors such as matrix effects and Compton scatter. This technology has been incorporated in a hand-held X-ray fluorescence lead paint analyzer system. A key design philosophy for this system was to maintain a very narrow, task-specific focus, the system was not designed to be an all purpose XRF analyzer, rather it is optimized to meet regulatory requirements of lead paint testing in the most efficient manner. The development of the LPA-1 system is an example of what can be accomplished by listening to the needs and desires of the users, rethinking the design of an existing technique and incorporating modern microprocessor technology.     

A new immune-competent animal model of mucosally derived squamous cell carcinoma.

OBJECTIVES: To develop an immune-competent animal model for mucosally derived squamous cell carcinoma (SCCA). STUDY DESIGN: Fifteen Fischer 344 rats were inoculated with 1, 2, 5, 10, or 20 x 10(6) FAT7 cells in their flanks. The animals were observed for tumor growth and metastasis. RESULTS: All animals developed tumors that grew exponentially. Pulmonary metastases developed in all animals and 13% developed lymph node metastases. CONCLUSION: The FAT7 flank tumor in Fischer 344 rats is a new animal model that closely resembles the behavior of human mucosal head and neck cancer. SIGNIFICANCE: The existence of an immune-competent, mucosally derived, and reliable animal model of SCCA that somewhat resembles human head and neck SCCA gives the opportunity to perform immune-modulating experiments on head and neck cancer in these animals. EBM rating: B-3.     

Multivisceral transplantation for abdominal tumors in children: A single center experience and review of the literature

Standard management of intra‐abdominal pediatric solid tumors requires complete resection. However, tumors with multiple organ and vascular involvement present a unique surgical challenge. We conducted a retrospective chart review of four patients, aged 2‐14 years, undergoing MVT for intra‐abdominal tumors with significant involvement of the visceral arteries and/or portomesenteric venous system at our institution. Indications for MVT included hepatocellular carcinoma, inflammatory myofibroblastic tumor, and two cases of hepatoblastoma. Grafts included liver, stomach, small bowel, and pancreas in all patients, with two patients also receiving spleens, and one, a partial esophageal transplant. Median hospital stay was 80 days. Postoperative complications included reoperation for abdominal hematoma and bowel obstruction, steroid responsive intestinal rejection, wound dehiscence, fungemia, seizures, and chyle leak with pleural effusion. One patient developed Epstein‐Barr virus‐associated complications which responded well to treatment. On follow‐up (range 2.8‐7.8 years), all patients have satisfactory graft function and no evidence of recurrent disease. MVT is an effective means of achieving complete gross resection of intra‐abdominal malignancies in patients with multiple organ and vascular involvement.     

Strategies That Facilitate Extraction-Free SARS-CoV-2 Nucleic Acid Amplification Tests

The COVID-19 pandemic has resulted in an unprecedented global demand for in vitro diagnostic reagents. Supply shortages and hoarding have impacted testing capacity which has led to inefficient COVID-19 case identification and transmission control, predominantly in developing countries. Traditionally, RNA extraction is a prerequisite for conducting SARS-CoV-2 nucleic acid amplification tests (NAAT); however, simplified methods of sample processing have been successful at bypassing typical nucleic acid extraction steps, enabling extraction-free SARS-CoV-2 NAAT workflows. These methods involve chemical and physical approaches that are inexpensive and easily accessible alternatives to overcome extraction kit supply shortages, while offering acceptable test performance. Here we provide an overview of three main sample preparation strategies that have been shown to facilitate extraction-free SARS-CoV-2 NAATs.     

Superior calcium bioavailability of effervescent potassium calcium citrate over tablet formulation of calcium citrate after Roux-en-Y gastric bypass

BackgroundCalcium supplementation is commonly recommended for patients after Roux-en-Y gastric bypass to avert bone loss. To test the hypothesis that effervescent (liquid) potassium-calcium-citrate (PCC) might be more bioavailable than a tablet formulation of calcium citrate (Citracal Petite), the present study compared a single dose response of the 2 compounds. The present study was conducted at the University of Texas Southwestern Medical School at Dallas.MethodsA total of 15 patients who had undergone Roux-en-Y gastric bypass were included in a 2-phase, crossover, randomized study comparing the single-dose bioavailability of PCC versus Citracal Petite. After following a restricted diet for 1 week, the participants ingested either a single dose of 400 mg elemental calcium as PCC or Citracal Petite. Sequential serum and urine samples were collected for a 6-hour period after the dose and analyzed for calcium, parathyroid hormone, and acid-base parameters.ResultsCompared with citracal petite, PCC significantly increased the serum calcium concentrations at 2, 3, and 4 hours after the oral load. The peak to baseline variation and increment in serum calcium (area under the curve) were significantly greater after PCC (P = .015 and P = .002, respectively). Concurrently, the baseline to nadir variation and decrement in serum parathyroid hormone (area over the curve) were significantly greater after PCC (P = .004 and P = .005, respectively). Moreover, compared with Citracal Petite, PCC caused a significantly greater increment in urinary citrate (P < .0001) and potassium (P = .0004) and a significantly lower increase in urinary ammonium (P = .045).ConclusionIn patients who have undergone Roux-en-Y gastric bypass, PCC was superior to Citracal Petite in conferring bioavailable calcium and suppressing parathyroid hormone secretion. PCC also provided an alkali load.     

Bench-to-bedside review: Rapid molecular diagnostics for bloodstream infection - a new frontier?

ABSTRACT: Among critically ill patients, the diagnosis of bloodstream infection poses a major challenge. Current standard bacterial identification based on blood culture platforms is intrinsically time-consuming and slow. The continuous evolvement of molecular techniques has the potential of providing a faster, more sensitive and direct identification of causative pathogens without prior need for cultivation. This may ultimately impact clinical decision-making and antimicrobial treatment. This review summarises the currently available technologies, their strengths and limitations and the obstacles that have to be overcome in order to develop a satisfactory bedside point-of-care diagnostic tool for detection of bloodstream infection.