Determination of camostat and its metabolites in human plasma - Preservation of samples and quantification by a validated UHPLC-MS/MS method.

OBJECTIVES: Camostat mesilate is a drug that is being repurposed for new applications such as that against COVID-19 and prostate cancer. This induces a need for the development of an analytical method for the quantification of camostat and its metabolites in plasma samples. Camostat is, however, very unstable in whole blood and plasma due to its two ester bonds. The molecule is readily hydrolysed by esterases to 4-(4-guanidinobenzoyloxy)phenylacetic acid (GBPA) and further to 4-guanidinobenzoic acid (GBA). For reliable quantification of camostat, a technique is required that can instantly inhibit esterases when blood samples are collected. DESIGN AND METHODS: An ultra-high-performance liquid chromatography-tandem mass spectrometry method (UHPLC-ESI-MS/MS) using stable isotopically labelled analogues as internal standards was developed and validated. Different esterase inhibitors were tested for their ability to stop the hydrolysis of camostat ester bonds. RESULTS: Both diisopropylfluorophosphate (DFP) and paraoxon were discovered as efficient inhibitors of camostat metabolism at 10 mM concentrations. No significant changes in camostat and GBPA concentrations were observed in fluoride-citrate-DFP/paraoxon-preserved plasma after 24 h of storage at room temperature or 4 months of storage at -20 °C and -80 °C. The lower limits of quantification were 0.1 ng/mL for camostat and GBPA and 0.2 ng/mL for GBA. The mean true extraction recoveries were greater than 90%. The relative intra-laboratory reproducibility standard deviations were at a maximum of 8% at concentrations of 1-800 ng/mL. The trueness expressed as the relative bias of the test results was within ±3% at concentrations of 1-800 ng/mL. CONCLUSIONS: A methodology was developed that preserves camostat and GBPA in plasma samples and provides accurate and sensitive quantification of camostat, GBPA and GBA by UHPLC-MS/MS.

Hormone-secreting adrenal tumours cause severe hypertension and high rates of poor pregnancy outcome; a UK Obstetric Surveillance System study with case control comparisons.

OBJECTIVE: To examine the management and outcomes of adrenal tumours in pregnancy. DESIGN: A national observational, cohort study over 4 years using the UK Obstetric Surveillance System (UKOSS). SETTING: Consultant-led obstetric units. PATIENTS: Women with phaeochromocytoma, primary aldosteronism or Cushing's syndrome diagnosed before or during pregnancy. METHODS: Clinical features of UKOSS cases were compared with those of women with adrenal tumours reported from 1985-2015. Nested case-control comparisons involving the UKOSS cases as well as those identified in the literature were performed for pregnancy outcome data using UKOSS controls with uncomplicated singleton (n = 2250) pregnancy and data from the Office of National Statistics (ONS). MAIN OUTCOME MEASURES: Incidence, management and frequency of adverse maternal and offspring outcomes of adrenal tumours in pregnancy. RESULTS: Fifteen pregnant women met the inclusion criteria: ten phaeochromocytoma, three primary aldosteronism and two Cushing's syndrome. All of the tumours had an incidence rate <2 per 100 000 pregnancies. Clinical symptoms were similar to those in non-pregnant women due to the hormones released. All women had severe hypertension, and in those diagnosed in pregnancy prior to conception. There was a significantly increased risk of adverse pregnancy outcomes in affected women, with increased rates of stillbirth, preterm labour and operative delivery. CONCLUSIONS: Adrenal tumours are associated with increased risks for pregnant women and their babies. Data on these tumours to inform practice are limited and international collaborative efforts are likely to be needed. TWEETABLE ABSTRACT: Study of hormone-secreting adrenal tumours in pregnancy linked with high BP and high rates of fetal morbidity.

A district general hospital experience of palliative biliary stenting.

BACKGROUND: Palliative management of malignant pancreaticobiliary (PB) disease typically takes the form of endoscopic biliary stenting with a covered metal stent. We set out to assess outcomes from endoscopic biliary stenting (endoscopic retrograde cholangiopancreatography, ERCP) for malignant disease in our district general hospital (DGH). METHODS: We identified patients with malignant PB disease who underwent primary ERCP between 2011 and 2012. Case notes were reviewed for clinical outcomes and involvement of palliative care. RESULTS: 38 patients underwent biliary stenting in this period. Median age was 75.6 years (53.6-99.8 years). 35 stents were placed for primary PB malignancy. 31 of these stents were covered metal stents and 6 were uncovered. Bilirubin decreased from a median of 218 to 112 µmol/L (median decrease 55 µmol/L). Complications occurred in the following 13 cases: 7 blocked stents (18.9%), 2 of which were associated with sepsis; 2 cases of stent migration (8.1%); 3 cases of biliary sepsis (8.1%) and 1 episode of pancreatitis (2.7%). Subsequently, 12 patients underwent a single repeat ERCP and 1 patient underwent 3 further ERCPs. Median survival following ERCP and stent was 78 days (10-806). 28 patients (76%) were known to the hospital palliative care team. CONCLUSIONS: Our DGH provides local service with complication rates comparable to those described in the literature. This allows care of patients with limited prognosis to be treated close to home. The majority of stent complications and mortality occur within 3 months. Input from the palliative care team is useful when considering whether a patient has a prognosis long enough to benefit from the procedure.

A rare occurrence of hairy cell leukemia in a congolese child: a presentation and challenge of diagnosis in low resource settings.

BACKGROUND: Hairy cell leukemia is a rare form of leukemia and has been rarely reported in African and pediatric population. OBSERVATION: We are reporting a 4-year-old child who was received for investigation for persistent anemia, prolonged fever, and thrombocytopenia. Bone marrow aspiration showed hypercellular marrow with cells characterized by irregular windblown-appearing cell borders with pseudopod-like projections. Our patient presented with hairy cell leukemia. CONCLUSION: The diagnosis was thought to be most consistent with hairy cell leukemia based on the distinctive morphology of the cells.

Does post-mastectomy radiotherapy represent a contraindication to skin-sparing mastectomy and immediate reconstruction: an update.

The use of skin-sparing mastectomy (SSM) to facilitate breast reconstruction is increasing due to a wide acceptance of improved cosmetic outcomes and evidence of equivalence in oncologic outcomes. The rates of patients undergoing mastectomy for whom post-mastectomy radiotherapy (PMRT) will be recommended is increasing as evidence of decreased loco-regional recurrence and increased survival mounts. PMRT may adversely effect complication rates and cosmetic outcomes for patients undergoing immediate breast reconstruction and PMRT--although the evidence for this is methodologically flawed. This article summarises the above evidence and highlights a reconstructive algorithm that may be used to mitigate the possible deleterious effects of PMRT on results.

Older rehabilitation patients are at high risk of malnutrition: evidence from a large Australian database.

BACKGROUND/OBJECTIVES: Routine nutrition screening is recommended for all older patients admitted to hospital however data on the prevalence of malnutrition in rehabilitation settings is sparse. This study assessed the nutritional status of older patients admitted to rehabilitation hospitals over a 5 year period and described the association between nutritional status and length of hospital stay (LOS) in this context. The usefulness of a recently revised version of the shortened MNA (MNA-SF) was also investigated. METHODS: A retrospective analysis was conducted of patients aged 65 + y admitted to two rehabilitation hospitals in New South Wales, Australia between 1st March 2003-30th June 2004, and 11th January 2005-10th December 2008. Nutritional status was determined on admission by trained dietitians using the full MNA instrument and the MNA-SF. Information on diagnosis-related grouping and length of stay (LOS) was obtained. RESULTS: Data was available for 2076 patients with a mean age of 80.6 (27.7) y. Thirty-three percent and 51.5% of patients were classified as malnourished and at nutritional risk, respectively. Controlling for date of admission and diagnosis related grouping, LOS was higher in malnourished and at risk groups compared to their well nourished peers (P < 0.001) by 18.5 and 12.4 days, respectively. MNA-SF demonstrated high sensitivity but relatively low specificity against the full MNA. CONCLUSION: The majority of older patients in the rehabilitation setting are nutritionally compromised which adversely influences LOS. In order to encourage more widespread screening, the MNA-SF may be able to replace the full MNA.

The use of thalidomide in the management of bleeding from a gastric cancer.

Medical management of severe gastrointestinal bleeding can present a therapeutic challenge. We describe a case of bleeding secondary to gastric cancer that failed to settle, despite treatment with tranexamic acid, etamsylate and sucralfate. Thalidomide was prescribed for its antiangiogenic properties. Bleeding settled within 1 week of starting 300 mg of thalidomide nocte. The effect appeared to be dose dependent, with bleeding recurring only when the dose was reduced to 100 mg of thalidomide nocte.

Training-induced improvement in lipid oxidation in type 2 diabetes mellitus is related to alterations in muscle mitochondrial activity. Effect of endurance training in type 2 diabetes.

AIM: We investigated whether or not, in type 2 diabetic (T2D) patients, an individualized training effect on whole-body lipid oxidation would be associated with changes in muscle oxidative capacity. METHODS: Eleven T2D patients participated in the study. Whole-body lipid oxidation during exercise was assessed by indirect calorimetry during graded exercise. Blood samples for measuring blood glucose and free fatty acids during exercise, and muscle oxidative capacity measured from skeletal muscle biopsy (mitochondrial respiration and citrate synthase activity), were investigated in the patients before and after a 10-week individualized training program targeted at LIPOXmax, corresponding to the power at which the highest rate of lipids is oxidized (lipid oxidation at LIPOXmax). RESULTS: Training induced both a shift to a higher-power intensity of LIPOXmax (+9.1+/-4.2W; P<0.05) and an improvement of lipid oxidation at LIPOXmax (+51.27+/-17.93 mg min(-1); P<0.05). The improvement in lipid oxidation was correlated with training-induced improvement in mitochondrial respiration (r=0.78; P<0.01) and citrate synthase activity (r=0.63; P<0.05). CONCLUSION: This study shows that a moderate training protocol targeted at the LIPOXmax in T2D patients improves their ability to oxidize lipids during exercise, and that this improvement is associated with enhanced muscle oxidative capacity.

Genomic DNA sequence comparison between two inbred soybean cyst nematode biotypes facilitated by massively parallel 454 micro-bead sequencing.

Heterodera glycines, the soybean cyst nematode (SCN), is a damaging agricultural pest that could be effectively managed if critical phenotypes, such as virulence and host range could be understood. While SCN is amenable to genetic analysis, lack of DNA sequence data prevents the use of such methods to study this pathogen. Fortunately, new methods of DNA sequencing that produced large amounts of data and permit whole genome comparative analyses have become available. In this study, 400 million bases of genomic DNA sequence were collected from two inbred biotypes of SCN using 454 micro-bead DNA sequencing. Comparisons to a BAC, sequenced by Sanger sequencing, showed that the micro-bead sequences could identify low and high copy number regions within the BAC. Potential single nucleotide polymorphisms (SNPs) between the two SCN biotypes were identified by comparing the two sets of sequences. Selected resequencing revealed that up to 84% of the SNPs were correct. We conclude that the quality of the micro-bead sequence data was sufficient for de novo SNP identification and should be applicable to organisms with similar genome sizes and complexities. The SNPs identified will be an important starting point in associating phenotypes with specific regions of the SCN genome.

Estradiol activates mast cells via a non-genomic estrogen receptor-alpha and calcium influx.

BACKGROUND: Allergic airway diseases are more common in females than in males during early adulthood. A relationship between female hormones and asthma prevalence and severity has been suggested, but the cellular and molecular mechanisms are not understood. OBJECTIVE: To elucidate the mechanism(s) by which estrogens enhance the synthesis and release of mediators of acute hypersensitivity. METHODS: Two mast cell/basophil cell lines (RBL-2H3 and HMC-1) and primary cultures of bone marrow derived mast cells, all of which naturally express estrogen receptor-alpha, were examined. Cells were incubated with physiological concentrations of 17-beta-estradiol with and without IgE and allergens. Intracellular Ca(2+) concentrations and the release of beta-hexosaminidase and leukotriene C(4) were quantified. RESULTS: Estradiol alone induced partial release of the preformed, granular protein beta-hexosaminidase from RBL-2H3, BMMC and HMC-1, but not from BMMC derived from estrogen receptor-alpha knock-out mice. The newly synthesized LTC(4) was also released from RBL-2H3. Estradiol also enhanced IgE-induced degranulation and potentiated LTC(4) production. Intracellular Ca(2+) concentration increased prior to and in parallel with mediator release. Estrogen receptor antagonists or Ca(2+) chelation inhibited these estrogenic effects. CONCLUSION: Binding of physiological concentrations of estradiol to a membrane estrogen receptor-alpha initiates a rapid onset and progressive influx of extracellular Ca(2+), which supports the synthesis and release of allergic mediators. Estradiol also enhances IgE-dependent mast cell activation, resulting in a shift of the allergen dose response.

A model plant pathogen from the kingdom Animalia: Heterodera glycines, the soybean cyst nematode.

The soybean cyst nematode, Heterodera glycines, adversely affects the production of soybean, Glycine max, in many areas of the world, particularly in the United States, where it is the most economically important soybean pathogen. Despite the availability of hundreds of H. glycines-resistant soybean cultivars, the nematode continues to be a major limiting factor in soybean production. The use of nonhost rotation and resistance are the primary means of reducing losses caused by the nematode, but each of these options has disadvantages. As a subject for study of nematode parasitism and virulence, H. glycines provides a useful model despite its obligately parasitic nature. Its obligately sexual reproduction and ready adaptation to resistant cultivars, formerly referred to as "race shift," presents an excellent opportunity for the study of virulence in nematodes. Recent advances in H. glycines genomics have helped identify putative nematode parasitism genes, which, in turn, will aid in the understanding of nematode pathogenicity and virulence and may provide new targets for engineering nematode resistance.

Estrogen receptor alpha (ERalpha) deficiency in macrophages results in increased stimulation of CD4+ T cells while 17beta-estradiol acts through ERalpha to increase IL-4 and GATA-3 expression in CD4+ T cells independent of antigen presentation.

The effects of 17beta-estradiol (E2) on immune function have been extensively reported. The effects are dependent on concentration and duration of exposure and potential differences in signaling between the known E2 receptors, estrogen receptors (ER) alpha and ERbeta. Through the use of ER-deficient mice, we and others have begun to demonstrate the role of the two known receptors in modulating immune functional activities. Previous studies have shown that cells of the innate immune system have altered function (bactericidal capacity) and patterns of cytokine expression (increased proinflammatory cytokine expression) through amelioration of ERalpha signaling. In this study, we extend these studies to analysis of T cell differentiation and proliferation in APC-dependent and APC-independent in vitro assay systems. Our results demonstrate that ERalpha deficiency in splenic macrophages, but not CD11c+ splenic dendritic cells pulsed with OVA significantly enhances proliferative responses and IFN-gamma production by transgenic OVA peptide-specific (OT-II) CD4+ T cells when compared with Ag-pulsed APC from wild-type littermates. The addition of E2 in this culture system did not significantly affect the production of IFN-gamma. In addition, when purified CD4+ T cells from ERalpha-deficient and wild-type littermates were stimulated with anti-CD3/CD28 Ab in the absence of E2, there were no significant differences in IFN-gamma or IL-4 production. However, the addition of E2 significantly increased IL-4 secretion, as well as increased GATA-3 mRNA levels from ERalpha-replete CD4+ T cells, while this effect was abrogated in ERalpha-deficient CD4+ T cells.

Management of asymptomatic cholelithiasis for patients awaiting renal transplantation.

BACKGROUND: There is no consensus regarding the most appropriate management of asymptomatic cholelithiasis in patients awaiting renal transplantation. Cholecystectomy is considered before renal transplantation because of potential worsened complications from cholelithiasis with posttransplantation immunosuppression. This study reviewed the outcomes for operative and nonoperative management of asymptomatic cholelithiasis in patients awaiting renal transplantation. METHODS: A retrospective chart review of all patients who received renal transplant at the authors' institution during the period 1994 to 2000 was completed. All patients underwent pretransplantation abdominal ultrasound. RESULTS: Of the 411 patients receiving renal transplants (242 men and 169 women with a mean age of 45.7 years), 32 had cholelithiasis at the pretransplantation workup (7.8%), and 35 had gallbladder abnormalities (8.5%): polyps, thickened wall, sludge, bile duct dilation. Before transplantation, 12 of the 32 patients (38%) with cholelithiasis underwent uncomplicated cholecystectomy. None of the remaining 19 patients with cholelithiasis required cholecystectomy after renal transplantation (mean follow-up period 6.2 years). Of the 35 patients with gallbladder abnormalities, 2 required post transplantation elective cholecystectomy. CONCLUSIONS: No evidence was found for increased morbidity related to cholelithiasis or gallbladder abnormalities after renal transplantation. As in the general population, the risks associated with asymptomatic cholelithiasis do not appear to warrant prophylactic cholecystectomy for patients awaiting renal transplantation.

A genetic linkage map of the soybean cyst nematode Heterodera glycines.

A genetic linkage map of the soybean cyst nematode (SCN) Heterodera glycines was constructed using a population of F2 individuals obtained from matings between two highly inbred SCN lines, TN16 and TN20. The AFLP fingerprinting technique was used to genotype 63 F2 progeny with two restriction enzyme combinations (EcoRI/MseI and PstI/TaqI) and 38 primer combinations. The same F2 population was also genotyped for Hg-cm-1 (H. glycines chorismate mutase-1), a putative virulence gene, using real-time quantitative PCR. Some of the markers were found to be distributed non-randomly. Even so, of the 230 markers analyzed, 131 could be mapped onto ten linkage groups at a minimum LOD of 3.0, for a total map distance of 539 cM. The Hg-cm-1 locus mapped to linkage group III together with 16 other markers. The size of the H. glycines genome was estimated to be in the range of 630-743 cM, indicating that the current map represents 73-86% of the genome, with a marker density of one per 4.5 cM, and a physical/genetic distance ratio of between 124 kb/cM and 147 kb/cM. This genetic map will be of great assistance in mapping H. glycines markers to genes of interest, such as nematode virulence genes and genes that control aspects of nematode parasitism.

Vacuum assisted closure: a review of development and current applications.

Vacuum assisted closure is being increasingly used for wound management. This review examines the history of its development and appraises the current evidence on its use so far.

Estrogen receptor-alpha deficiency promotes increased TNF-alpha secretion and bacterial killing by murine macrophages in response to microbial stimuli in vitro.

In this series of studies, we determined the potential role of intracellular estrogen receptors (ER), ERalpha and ERbeta, on macrophage function in response to bacterial stimuli. The sex hormone 17beta-estradiol (E(2)) and ER have been shown to modulate inflammatory responses as well as T helper cell type 1 (TH1)/TH2 responses. The mechanisms E(2) and its receptors use to alter these immune functions remain largely unknown. ERalpha and ERbeta possess complex actions in tissues where they are expressed. We have characterized the receptor repertoire of murine dendritic cells and thioglycollate-elicited peritoneal macrophages (PM). Both cell types express mRNA for ERalpha. Neither cell type expressed detectable amounts of ERbeta mRNA, as determined by reverse transcriptase-polymerase chain reaction using exon-specific primers spanning each of the seven intron/exon junctions. Primary macrophages from ERalpha- and ERbeta-deficient severe combined immunodeficiency mice [ERalpha knockout (KO) and ERssKO, respectively] were used to delineate the effects and potential mechanisms via which steroid receptors modulate macrophage function. ERalpha-deficient PM exposed ex vivo to lipopolysaccharide or Mycobacterium avium exhibited significant increases in tumor necrosis factor alpha (TNF-alpha) secretion as well as reduction in bacterial load when compared with wild-type (WT) PM. In contrast, ERbeta-deficient PM possessed no significant difference in TNF-alpha secretion or in bacterial load when compared with WT littermates. These studies suggest that ERalpha, but not ERbeta, modulates murine PM function.

Impaired sarcolemmal vesicle lactate uptake and skeletal muscle MCT1 and MCT4 expression in obese Zucker rats.

The present experiments were undertaken to characterize 1) the hindlimb muscle mass lactate uptake and 2) the expression of monocarboxylate transporter isoforms MCT1 and MCT4, as well as lactate dehydrogenase (LDH) isozyme distribution, in various skeletal muscles of Zucker fa/fa rats taken as a model of insulin resistance-related obesity. Initial lactate uptake at six different concentrations was measured in sarcolemmal vesicles (SV) by use of L-[U-(14)C]lactate. Compared with controls, the maximal rate of lactate uptake and affinity were decreased in SV of Zucker rats (approximately 30%) in which MCT4 content was significantly decreased (P < 0.05). MCT4 expression was decreased in soleus, extensor digitorum longus, and red tibialis anterior (RTA; P < 0.05), but not in white tibialis anterior, whereas MCT1 expression was decreased only in RTA of Zucker rats (P < 0.05). Obesity led to a shift toward type M-LDH isozyme in mixed muscles. We conclude that obesity leads to changes in muscular MCT1 and MCT4 expression, which, when associated with LDH isozyme redistribution, may contribute to the hyperlactatemia noted in insulin resistance.

Alterations of medial preoptic area neurons following pregnancy and pregnancy-like steroidal treatment in the rat.

There is a marked increase in the maternal behavior displayed by a female rat following pregnancy-due primarily to exposure to the gonadal hormones progesterone and estradiol (P and E(2), respectively). We examined Golgi-Cox silver-stained, Vibratome-sectioned neurons visualized and traced using computerized microscopy and image analysis. In Part One, we examined the hormonal-neural concomitants in the medial preoptic area (mPOA), an area of the brain that regulates maternal behavior, by comparing cell body size (area in microm(2); also referred to as soma and perikaryon) in the mPOA and cortex of five groups (n = 4-6/group) of ovariectomized (OVX-minus), diestrous, sequential P and E(2)-treated (P+E(2)), late-pregnant, and lactating rats; for Part Two, we examined a subset of mPOA neurons, which were traced in their entirety, from these same subjects. In Part One, whereas there was no difference between OVX-minus and diestrous females, both had smaller somal areas compared to OVX+P+E(2)-treated and late-pregnant females. The area of the soma returned to diestrous/OVX-minus levels in the lactating females. We found no change among the five groups in area of cell body in cortical neurons, which generally lack steroid receptors. In Part Two, which included a more detailed morphometric analysis of mPOA neurons, we examined several additional measures of dendritic structure, including number of proximal dendritic branches (the largest proximal dendrite was defined as the one with the largest diameter leaving the soma); cumulative length of the largest proximal dendrite; area of the cell body; number of basal dendrites; cumulative basal dendritic length; number of basal dendritic branches; and branch-point (distance from cell body to first branch of largest proximal dendrite). Again, we found similar effects on cell body size as in Part One, together with effects on number of basal dendritic branches and cumulative basal dendritic length in pregnant and P+E(2)-treated groups compared to OVX, diestrous, and lactating. An increase in somal area denotes increased cellular activity, and stimulatory effects on additional neuronal variables represents modifications in information processing capacity. Pregnancy and its attendant hormonal exposure, therefore, may stimulate neurons in the mPOA, which then contribute (in an as yet undetermined manner) to the display of maternal behavior. During the postpartum lactational period, when cues from pups primarily maintain maternal attention, the neuronal soma appears to return to a pre-pregnancy, non-hormonally dependent state, whereas other aspects of the dendrite remain altered. Collectively, these data demonstrate a striking plasticity in the brains of females that may be reflected in modifications in behavior.

Inspection of lead aprons: criteria for rejection.

Lead aprons utilized by personnel performing fluoroscopy are routinely inspected for damage to comply with the requirements of hospital accrediting organizations. Fluoroscopic or radiographic examination of lead aprons may reveal imperfections ranging from small pinholes to large tears. Currently, there are no standards establishing a criteria for acceptance or rejection of lead aprons. As a consequence, many facilities have established arbitrary rejection criteria. Often lead aprons are discarded due to small imperfections, a practice that can become costly to these institutions. We have calculated increases in doses to the whole body for varying sizes of holes, including special consideration of the effects on effective dose equivalent when the hole is over the testes and thyroid. ALARA standards for cost per personsievert averted are used to establish a rational basis for criteria of acceptance or rejection of lead aprons.

Radiation safety education for laboratory animal science.

Students enrolled in the laboratory animal science graduate program at MCP Hahnemann University seek to gain entrance to veterinary school or to manage an animal facility within an academic institution, pharmaceutical or biotechnology company conducting biomedical research. Ongoing interaction between faculty in the radiation oncology, radiation safety, and lab animal science disciplines revealed an acute need for radiation safety education for laboratory animal science students who will likely interact with researchers either designing and writing protocols for animal studies using radiation or radioactive materials, or veterinary staff who will use sources of radiation to diagnose and/or treat possible animal injuries and diseases. A core course in the Radiation Sciences graduate program was modified to address the needs of these students, instructing them in radiation safety, detection and counting instrumentation, and radiation biology. These fundamental areas were integrated to help the students gain a sound, basic knowledge of radiation and radioactive materials used in biomedical research.