Albumin and calcium reference interval using healthy individuals and a data-mining approach

BACKGROUND

Harmonization of reference intervals for analytes that have a sound calibration and metrological traceability is a widely recommended practice. The UK Pathology Harmony has recently harmonized reference intervals for calcium and albumin. In this study, we have determined the reference intervals for calcium and albumin on the UK's most commonly used analytical platforms.

METHOD

A prospective reference population of healthy individuals was recruited according to the IFCC CRIDL criteria. A second indirect population was collected from 14 primary care setting and measured in laboratories using various analytical platforms and methods (Roche, Abbott, Beckman and Siemens analytical platforms).

RESULTS

In total, 299 subjects were recruited; the central 95th centile values for calcium for three out of four analytical platforms were in a close agreement with UK Pathology Harmony reference intervals of 2.2-2.6 mmol/L. Reference intervals of BCG methods from both cohorts and irrespective of analytical platforms were higher for both lower and upper reference limits than those for BCP. In comparison, the indirect study showed an age-related variation. The younger population reference intervals varied by up to 5.7% at the lower reference limit and up to 12% at the upper reference limit compared with Pathology Harmony reference intervals, and the older population showed a variation of up to 14% at both limits.

CONCLUSION

While calcium reference intervals can be a subject for harmonization, albumin reference intervals studied showed large variation which is unsupportive of embracing a common reference interval for albumin.

The impact of the analytical performance specifications of calcium and albumin on adjusted calcium

Aim

The generation of accurate, comparable results from traceable measurement procedures is a primary goal in harmonization efforts. In this study, the analytical performance of routine methods for calcium and albumin measurement is assessed to define the impact of the analytical bias of calcium and albumin on adjusted calcium equation performance and on reference intervals.

Method

In collaboration with the Wales External Quality Assurance Scheme, six months’ worth of anonymized data that cover a concentration range of clinical interest were collected. The data were grouped by analytical platforms/methods.

Results

Albumin BCG methods are positively biased (8%) to BCP methods. The overall bias for BCP methods ranges from 5.1 to –4.3% and the overall bias for BCG methods is from 2 to –6.7%. Bias for both methods is higher than the allowable minimal bias for albumin. Calcium concentrations for Roche Cobas CPC and NM-BAPTA, Beckman Arsenazo III, Abbott Architect Arsenazo III were within bias of 1.5 to –1%. However, Siemens calcium methods CPC and Arsenazo III appear to suffer from concentration-dependent bias ranging from +3 to –6%, which exceeds even the minimal allowable limits for calcium (1.3%). Adjusted calcium shows significant bias of 11%. Even with the exclusion of Siemens Advia, the scatter of adjusted calcium results exceeds that for total calcium.

Conclusion

This study shows wider than acceptable analytical variation for albumin and calcium. This variation may contribute to overall adjusted calcium equations variation and invalidate the application of a harmonized reference interval for calcium and albumin.

The effect of different analytical platforms and methods on the performance of population-specific adjusted calcium equation

Background

A recent attempt to improve the diagnostic value of adjusted calcium addressed a primary care-specific adjusted calcium equation, but validated the new equation for Roche Cobas, BCG and NM-BAPTA methods only. In this study, we aim to validate a population-specific equation for other methods and platforms.

Method

We collected retrospective patient data-sets from 15 hospital laboratories using a range of commercially available analytical platforms and methods for calcium and albumin measurements. Raw data-sets were collected and filtered according to Payne’s criteria, and separate adjusted calcium equations were derived for hospitalized and primary care patients.

Results

Mean albumin and calcium results were significantly higher in primary care populations ( P <  0.0001). The prevalence of hypocalcaemia using adjusted calcium ranged between 6% and 44% for inpatient data-sets and was higher in users of BCG methods. The application of community-specific adjustment equation to primary care data-sets reduced the prevalence of hypocalcaemia (mean 1.7%, range 0.8–3.7%).

Conclusion

We demonstrated that the use of a community-specific calcium adjustment equation to a primary care population reduces both the percentage and the variation of hypocalcaemia between different laboratories.

Prospective study comparing the outcome of a population-specific adjusted calcium equation to ionized calcium

Background

Calcium circulates bound to albumin and changes in albumin concentration will therefore affect total calcium measurements. In order to mitigate this, correction factors are frequently used. The most widely used correction equation was described by Payne and colleagues in 1973. This equation was derived from well-defined hospitalized patients’ data. Current clinical practice is consistent with the general application of the adjusted calcium equation irrespective of clinical setting. This study aims to assess the validity of this approach by the derivation of a community care-specific adjusted calcium equation (‘community equation’) and the comparison of its performance to a hospitalized patient equation and ionized calcium.

Method

Retrospective data were collected according to Payne’s criteria from an inpatient and community care setting. Data were used to derive the two equations: the in-patient equation and community equation. The outcome of these equations was compared with ionized calcium obtained from 123 healthy participants.

Results

The community equation correctly identified the calcium status of 92% of the 123 healthy participants, while the inpatient equation identified 46% only. Regression analysis against ionized calcium showed a higher R2 for the community equation than for the inpatient equation. Furthermore, we have shown that mean albumin and calcium concentrations are significantly different between these two populations.

Conclusion

In this study, we found that the diagnostic accuracy of the adjusted calcium equation in ambulant patients was improved by the derivation of a population-specific equation for the community care setting.

Exploring natural product chemistry and biology with multicomponent reactions. 5. Discovery of a novel tubulin-targeting scaffold derived from the rigidin family of marine alkaloids

We developed synthetic chemistry to access the marine alkaloid rigidins and over 40 synthetic analogues based on the 7-deazaxanthine, 7-deazaadenine, 7-deazapurine, and 7-deazahypoxanthine skeletons. Analogues based on the 7-deazahypoxanthine skeleton exhibited nanomolar potencies against cell lines representing cancers with dismal prognoses, tumor metastases, and multidrug resistant cells. Studies aimed at elucidating the mode(s) of action of the 7-deazahypoxanthines in cancer cells revealed that they inhibited in vitro tubulin polymerization and disorganized microtubules in live HeLa cells. Experiments evaluating the effects of the 7-deazahypoxanthines on the binding of [(3)H]colchicine to tubulin identified the colchicine site on tubulin as the most likely target for these compounds in cancer cells. Because many microtubule-targeting compounds are successfully used to fight cancer in the clinic, we believe the new chemical class of antitubulin agents represented by the 7-deazahypoxanthine rigidin analogues have significant potential as new anticancer agents.

Bulbispermine: a crinine-type Amaryllidaceae alkaloid exhibiting cytostatic activity toward apoptosis-resistant glioma cells

The Amaryllidaceae alkaloid bulbispermine was derivatized to produce a small group of synthetic analogues. These, together with bulbispermine's natural crinine-type congeners, were evaluated in vitro against a panel of cancer cell lines with various levels of resistance to pro-apoptotic stimuli. Bulbispermine, haemanthamine, and haemanthidine showed the most potent antiproliferative activities as determined by the MTT colorimetric assay. Among the synthetic bulbispermine analogues, only the C1,C2-dicarbamate derivative exhibited notable growth inhibitory properties. All active compounds were found not to discriminate between the cancer cell lines based on the apoptosis sensitivity criterion; they displayed similar potencies in both cell types, indicating that the induction of apoptosis is not the primary mechanism responsible for antiproliferative activity in this series of compounds. It was also found that bulbispermine inhibits the proliferation of glioblastoma cells through cytostatic effects, possibly arising from rigidification of the actin cytoskeleton. These findings lead us to argue that crinine-type alkaloids are potentially useful drug leads for the treatment of apoptosis-resistant cancers and glioblastoma in particular.

Unprecedented C-2 arylation of indole with diazonium salts: Syntheses of 2,3-disubstituted indoles and their antimicrobial activity

A novel reaction of indole with aryldiazonium salts leading to the formation of 2-aryl-3-(arylazo)indoles was discovered. The products were found to possess potent anti-MRSA and anti-LLVRE activities. The SAR studies indicate that the potentially metabolically labile azo functionality can be replaced with ether oxygen and thioether sulfur atoms without any loss of activity.

Ghrelin does not orchestrate the metabolic changes seen in fasting but has significant effects on lipid mobilisation and substrate utilisation

OBJECTIVE

Short-term fasting is associated with increased GH pulsatility and mobilisation of fats, but underlying mechanisms are unclear. We studied ghrelin's role during fasting and the effects of exogenous ghrelin on lipid mobilisation.

DESIGN

Randomised placebo-controlled study.

METHODS

In this study, ten controls (body mass index (BMI) 23.3±3.2), ten morbidly obese subjects (BMI 50.1±10.6) and six post-gastrectomy subjects (BMI 25.2±1.0) were fasted for 36  h undergoing regular blood sampling. On a separate occasion, subjects were infused with either i.v. ghrelin (5  pmol/kg per min) or saline over 270  min.

RESULTS

Obese and post-gastrectomy subjects had lower ghrelin compared with controls (ANOVA, P=0.02) during the fast. Controls and gastrectomy subjects showed a similar increase in GH pulsatility, circulating non-esterified fatty acids (NEFA) and 3β-hydroxybutyrate (3 HB). Obese subjects had an impaired GH response (P<0.001), reduced excursions of 3 HB (P=0.01) but no change in NEFA excursions (P=0.09) compared with controls. Ghrelin infusion increased GH, NEFA and ketone bodies (ANOVA, P<0.0001) in all the three groups, but GH response was impaired in the obese subjects (P=0.001). Ghrelin also induced a significant (ANOVA, P=0.004) biphasic NEFA response to meals in all the subjects.

CONCLUSIONS

Despite low circulating ghrelin, gastrectomy subjects maintain a normal metabolic response to fasting, implying that ghrelin plays a minimal role. In contrast, infused ghrelin has significant effects on lipid mobilisation and induces a marked biphasic NEFA response to meals. Hence, ghrelin may play a significant role in meal-related substrate utilisation and metabolic flexibility.

The four-variable modification of diet in renal disease formula underestimates glomerular filtration rate in obese type 2 diabetic individuals with chronic kidney disease

AIMS/HYPOTHESIS

GFR is commonly estimated using the four-variable Modification of Diet in Renal Disease (MDRD) formula and this forms the basis for classification of chronic kidney disease (CKD). We investigated the effect of obesity on the estimation of glomerular filtration rate in type 2 diabetic participants with CKD.

METHODS

We enrolled 111 patients with type 2 diabetes mellitus in different stages of CKD. GFR was measured using (51)Cr-labelled EDTA plasma clearance and was estimated using the four-variable MDRD formula.

RESULTS

The bias between estimated and measured GFR was -22.4 (-33.8 to -11.0) p < 0.001 in the obese group compared with -6.04 (-17.6 to -5.5) p = 0.299 in the non-obese group. When GFR was indexed to body surface area of 1.73 m(2), the bias remained significant at -9.4 (-13.4 to -5.4) p < 0.001 in the obese participants.

CONCLUSIONS/INTERPRETATION

This study suggests that the four-variable MDRD formula significantly underestimates GFR in obese type 2 diabetic participants with CKD.

One-pot multicomponent synthesis of diversely substituted 2-aminopyrroles. A short general synthesis of rigidins A, B, C, and D

Privileged medicinal scaffolds based on the structures of tetra- and pentasubstituted 2-aminopyrroles were prepared via one-pot multicomponent reactions of structurally diverse aldehydes and N-(aryl-, hetaryl-, alkylsulfonamido)acetophenones with activated methylene compounds. This methodology was used in a four-step synthesis of alkaloids rigidins A, B, C, and D in overall yields of 61%, 58%, 60%, and 53%, respectively. Of these, rigidins B, C, and D were synthesized for the first time.

Pegvisomant interference in GH assays results in underestimation of GH levels

INTRODUCTION

Pegvisomant use in acromegaly negates the use of GH levels to monitor disease activity. To achieve antagonism, plasma concentrations must be approximately 1000-fold greater than GH which with the high homology between the peptides makes GH measurement a challenge when pegvisomant is present.

OBJECTIVE

We investigated the effect of pegvisomant on GH measured using commercially available assays.

METHODS

Pooled serum samples with GH concentrations <0.38, 3.85 and 7.69 microg/l were spiked with increasing pegvisomant concentrations (9000-494 000 microg/l). Samples were analysed by the Nichols Advantage, DPC Immulite 2000, Diasorin IRMA, Beckman Access Dxl, Tosoh AIA and Wallac Delfia assays.

RESULTS

With baseline GH <0.38 microg/l measured levels were <0.38 in all assays except Nichols, Diasorin and Beckman where GH peaked at 1.5, 9.6 and 17.7 micarog/l respectively at low pegvisomant concentrations, falling thereafter. With the other two samples, measured GH levels progressively fell with increasing pegvisomant concentrations, except the Beckman assay where an increase (30.8 microg/l) was seen at a pegvisomant concentration of 9000 microg/l; and Diasorin and Tosoh where smaller increases were seen at lower pegvisomant concentrations, levels gradually falling thereafter.

CONCLUSION

The presence of pegvisomant resulted in artefactually low measured GH in most assays. We speculate this fall is due to assay antibody-binding pegvisomant, reducing the amount of available antibody to bind actual GH thereby producing less sandwich formation: the 'high-dose hook' effect. In most assays, this effect is modest and results in lower GH, but the level of interference makes them unsuitable for studies on the influence of pegvisomant on GH neuroregulation.

Composting is an effective treatment option for sanitization of Phytophthora ramorum-infected plant material

AIMS

To determine the effects of heat and composting treatments on the viability of the plant pathogen Phytophthora ramorum grown on both artificial and various natural substrates.

METHODS AND RESULTS

Phytophthora ramorum was grown on V8 agar, inoculated on bay laurel leaves (Umbellularia californica) and on woody tissues of coast live oak (Quercus agrifolia). Effects on growth, viability and survival were measured as a result of treatment in ovens and compost piles. Direct plating onto PARP medium and pear-baiting techniques were used to determine post-treatment viability. No P. ramorum was recovered at the end of the composting process, regardless of the isolation technique used. By using a PCR assay designed to detect the DNA of P. ramorum, we were able to conclude the pathogen was absent from mature compost and not merely suppressed or dormant.

CONCLUSIONS

Some heat and composting treatments eliminate P. ramorum to lower than detectable levels on all substrates tested.

SIGNIFICANCE AND IMPACT OF THE STUDY

Composting is an effective treatment option for sanitization of P. ramorum-infected plant material. Assaying for pathogen viability in compost requires a direct test capable of differentiating between pathogen suppression and pathogen elimination.

Conversion to dementia from mild cognitive disorder: the Cache County Study

OBJECTIVE

To examine 3-year rates of conversion to dementia, and risk factors for such conversion, in a population-based sample with diverse types of cognitive impairment.

METHODS

All elderly (aged 65 or older) residents of Cache County, UT, were invited to undergo two waves of dementia screening and assessment. Three-year follow-up data were available for 120 participants who had some form of mild cognitive impairment at baseline. Of these, 51 had been classified at baseline with prodromal Alzheimer disease (proAD), and 69 with other cognitive syndromes (CS).

RESULTS

Three-year rates of conversion to dementia were 46% among those with cognitive impairment at baseline. By comparison, 3.3% without impairment converted to dementia in the interval. Among converters, AD was the most common type of dementia. In individuals with at least one APOE epsilon4 allele, those with proAD or CS exhibited a 22- to 25-fold higher risk of dementia than cognitively unimpaired individuals (vs 5- to 10-fold higher risk in those without epsilon4).

CONCLUSIONS

Individuals with all types of mild cognitive impairment have an elevated risk of dementia over 3 years, more so in those with an APOE epsilon4 allele. These results suggest value in dementia surveillance for broad groups of cognitively impaired individuals beyond any specific category, and utility of APOE genotyping as a prognostic method.

Therapy of circadian rhythm disorders in chronic fatigue syndrome: no symptomatic improvement with melatonin or phototherapy

BACKGROUND

Patients with chronic fatigue syndrome (CFS) show evidence of circadian rhythm disturbances. We aimed to determine whether CFS symptoms were alleviated by melatonin and bright-light phototherapy, which have been shown to improve circadian rhythm disorders and fatigue in jet-lag and shift workers.

DESIGN

Thirty patients with unexplained fatigue for > 6 months were initially assessed using placebo and then received melatonin (5 mg in the evening) and phototherapy (2500 Lux for 1 h in the morning), each for 12 weeks in random order separated by a washout period. Principal symptoms of CFS were measured by visual analogue scales, the Shortform (SF-36) Health Survey, Mental Fatigue Inventory and Hospital Anxiety and Depression Scale. We also determined the circadian rhythm of body temperature, timing of the onset of melatonin secretion, and the relationship between these.

RESULTS

Neither intervention showed any significant effect on any of the principal symptoms or on general measures of physical or mental health. Compared with placebo, neither body temperature rhythm nor onset of melatonin secretion was significantly altered by either treatment, except for a slight advance of temperature phase (0.8 h; P = 0.04) with phototherapy.

CONCLUSION

Melatonin and bright-light phototherapy appear ineffective in CFS. Both treatments are being prescribed for CFS sufferers by medical and alternative practitioners. Their unregulated use should be prohibited unless, or until, clear benefits are convincingly demonstrated.

Radioimmunoassay for the measurement of thrombospondin in plasma and breast cyst fluid: validation and clinical application

Thrombospondin is an adhesive protein that has been implicated in malignancy, specifically in tumour progression and angiogenesis. We developed a radioimmunoassay for the measurement of thrombospondin in plasma and breast cyst fluid. The assay exhibited high accuracy, with recoveries of 102-136% and acceptable imprecision, with an intra-assay coefficient of variation (CV) of <7.5% across the analytical range 30-1000 ng/mL and inter-assay CV of 4.4% and 7.7% at 152 and 224 ng/mL, respectively. Thrombospondin measured in the breast cyst fluid of patients with gross cystic disease of the breast showed that patients with type II (Na+) cysts had significantly higher concentrations than type I (K+) cysts. The plasma thrombospondin reference range was determined as 131-274 ng/mL. Patients with breast cancer had significantly higher plasma thrombospondin concentrations than normal individuals or patients with benign breast disease. Plasma thrombospondin was higher in breast cancer patients with lymph node involvement.

Expansion/deletion of mature T cells exposed to endogenous superantigens in vivo

Previous studies have shown that in thymectomized hosts exposure of mature T cells to Mlsa (mtv-7) Ag in vivo leads to specific tolerance and the disappearance of Mlsa-reactive V beta 6+ T cells after an initial phase of T cell expansion. To investigate the factors controlling postthymic elimination of mature T cells, we examined T cell responses to Mlsa and other endogenous superantigens in a number of different strain combinations. The results show that the extent of T cell expansion/deletion is influenced by various factors, including the H-2 haplotype of the host and the particular V beta studied. Collectively, the results suggest that the extent of elimination of mature T cells is variable and may be a function of high avidity interactions with APC.

Expansion/deletion of mature T cells exposed to endogenous superantigens in vivo

Previous studies have shown that in thymectomized hosts exposure of mature T cells to Mlsa (mtv-7) Ag in vivo leads to specific tolerance and the disappearance of Mlsa-reactive V beta 6+ T cells after an initial phase of T cell expansion. To investigate the factors controlling postthymic elimination of mature T cells, we examined T cell responses to Mlsa and other endogenous superantigens in a number of different strain combinations. The results show that the extent of T cell expansion/deletion is influenced by various factors, including the H-2 haplotype of the host and the particular V beta studied. Collectively, the results suggest that the extent of elimination of mature T cells is variable and may be a function of high avidity interactions with APC.

Phase II study of carboplatin (CBDCA) in refractory multiple myeloma. A Southwest Oncology Group study

Nineteen patients with multiple myeloma resistant to standard alkylating agent therapy or to the VAD regimen received carboplatin at a planned daily dose of 100 mg/M2 on four successive days. Two patients erroneously received a four-fold higher drug dose resulting in bone marrow aplasia and death without antitumor effect in one patient with post-mortem examination. No anti-tumor effect was observed among 15 patients evaluable for response (two lacked follow-up examination of tumor markers). Major toxicities were hematologic and included grade > or = III, leukopenia in 9, thrombocytopenia in 6 and anemia in 3 of the 17 evaluable patients. Their median survival was 9 months. These results indicate that carboplatin is inactive in refractory multiple myeloma.

A phase I study of escalating interferon alpha-2a combined with 5-fluorouracil and leucovorin in patients with gastrointestinal malignancies

On the basis of preclinical data showing synergy between 5-fluorouracil (5-FU), leucovorin (LV) and IFN-alpha-2a, a phase I study was carried out to determine the maximum tolerable dose (MTD) of IFN-alpha-2a with this combination in patients with gastrointestinal malignancies. The treatment consisted of 370 mg/m2 5-FU and 200 mg/m2, LV on days 1 to 5, and IFN-alpha-2a on days 1 to 5 of the first week of chemotherapy and on days 1, 3, 5 of each subsequent week, on a 28-day cycle. Six patients with colorectal, 3 with pancreas, 2 with oesophagus, 2 with hepatocellular and one with gastric cancer were treated. At level III (5 x 10(6) U/m2) all patients experienced grade 3 or 4 toxicity during the first 56 days of treatment and the MTD was declared level II. Grade 3 toxicity comprised of anorexia, mucositis, diarrhoea, and fatigue; in one instance, grade 4 neutropenia occurred. Ten patients were evaluable for response, one patient with an oesophageal cancer had a minor response and one patient with rectal cancer and liver metastases had a radiological complete response lasting 3 months. The recommended dose for this schedule in phase II studies is 5-FU 370 mg/m2, LV 200 mg/m2, and IFN-alpha-2a 4 x 10(6) U/m2.

Hemoptysis following Mustard repair: a late complication

Hemoptysis was the presenting symptom in a 4-year, 11-month-old male who had had a Mustard operation for hemodynamic correction of transposition of the great vessels at the age of five months. Chest roentgenography demonstrated hyperlucency of the left lung and tomography showed compression and narrowing of left main stem bronchus. Angiography documented the absence of antegrade flow in the left pulmonary artery and no pulmonary venous drainage on the left. The left lung was supplied by bronchial collateral arteries which drained by retrograde filling of the left pulmonary artery. It is surmised that pulmonary venous drainage on the left was compromised at surgery and that the dilated main pulmonary artery compressed the left main stem bronchus. This combination promoted bronchial collateral ingrowth. Hemoptysis is a complication of enlargement of bronchial collateral vessels.

Link between caudal regression and Vater syndromes

A variant between caudal and regression and Vater syndromes is presented which was significant anomalies of the genitourinary tract. The patient has a normal 46XX karyotype with the following urogenital anomalies: solitary pelvic kidney with megacalycosis, high ureteral bud or diverticulum, and ectopic insertion of the ureter into the proximal urethra; as well as, sacral agenesis, vaginal atresia, aberrant gonadal tissue, and uterine agenesis.