Statistical challenges posed by uncontrolled master protocols: sensitivity analysis of the vemurafenib study.

Within the evidentiary hierarchy of experimental inquiry, randomized trials are the gold standard. Oncology patients enter clinical studies with diverse lifestyles, treatment pathways, host tissue environments, and competing comorbidities. Randomization attempts to balance prognostic characteristics among study arms, thereby enabling statistical inference of 'average benefit' and attribution to the studied therapies. In contrast, interpretations of uncontrolled trials require additional scrutiny to attempt to place the findings in the context of external evidence. Counter-factual reasoning and speculation across trials may be obscured by the disproportionate enrollment of prognostic subpopulations which may be unknown from publications of trial reports. Recent modifications to the regulatory environment (Food and Drug Administration Safety and Innovation Act) have elevated the importance of non-comparative trials. Moreover, the emergence of recent innovations in precision medicine have yielded trial designs that partition potentially heterogeneous subpopulations into 'statistically exchangeable' cohorts by histologies, or genetic alterations, further elevating the importance of single-cohort analyses. As patient cohorts become ever more refined into smaller targeted subsets, consumers of reports of uncontrolled trials should be further empowered with improvements in reporting practices that better describe the enrolled prognostic subpopulations and importantly their association with study end points. This article demonstrates the issue with a sensitivity analysis of the findings reported in a recent trial that was devised to evaluate the preliminary clinical efficacy of vemurafenib in BRAF V600 mutation-positive nonmelanoma cancers.

Comparing patient-generated blood glucose diary records with meter memory in diabetes: a systematic review.

AIMS: To synthesize evidence relating to comparisons between patient-generated blood glucose records and meter memory in diabetes and to identify any predictors of agreement. METHODS: A systematic literature search was performed to identify articles comparing meter and diary records in those unaware of this assessment. RESULTS: Eleven observational studies, covering patients with Type 1, Type 2 and gestational diabetes were included spanning 1984-2009. Failure to record blood glucose measurements in the diary was the most extensive 'error', but addition of values, which were not measured, was a greater cause for concern. When present to a high degree, 'errors' lead to decreased variability in diary records compared with meter records. Allowing for a minimal amount of disagreement, just over 50% of adult diaries can be considered as 'accurate/reliable'. Disagreements were most extensive in teenagers and young adults, but the pregnant populations were only slightly better. Agreement was not related to sex, number of insulin injections or duration of monitoring. Those who were younger were more likely to have 'errors', while those who monitored more frequently had more 'accurate' diaries. CONCLUSIONS: The lack of meter-diary agreement suggests that the real reason for monitoring is not understood by many patients, raising issues about motivation, perceived need to impress healthcare providers and denial of poor control. Considering that diaries are used to inform decisions about therapy when HbA1c is raised or in pregnancy, when HbA1c is not suitable, there is significant cause for concern in relation to their clinical utility.

Provision of laboratory services for lipid analysis in the United Kingdom.

BACKGROUND: National guidelines have been developed in the UK to reduce coronary heart disease mortality. This audit assesses provision of lipid analyses by UK Clinical Biochemistry services to support their implementation. METHODS: Audit standards were derived from published guidelines. A questionnaire based on these was circulated to all UK Clinical Biochemistry laboratories. RESULTS: Of 108 replies, routine lipid profiles included triglycerides, HDL-, LDL-cholesterol and total:HDL cholesterol ratio in 98, 85, 72 and 44%, respectively. Only 33% and 27% analysed triglycerides and HDL, respectively, when asked simply to measure cholesterol. Seventy-six percent of the reports stated whether specimens were collected after fasting. For primary prevention, 46% of laboratories stated results should be interpreted in association with other risk factors; 20% referred explicitly to national/local guidelines. Only 19 laboratories quoted secondary prevention treatment thresholds for total cholesterol or LDL-cholesterol. Sixty laboratories occasionally added extra tests and/or interpretive comments. Eight laboratories appeared to provide no input from senior medical/scientific staff into report validation. CONCLUSIONS: These results indicate scope for improvement in the provision of lipid analyses and of information to support their interpretation. We recommend laboratories should routinely provide LDL- and non-HDL-cholesterol results, and that reports should quote treatment thresholds/targets in keeping with current guidelines.

Beneficial metabolic actions of a stable GIP agonist following pre-treatment with a SGLT2 inhibitor in high fat fed diabetic mice.

The purpose of the present study was to examine if a stable glucose-dependent insulinotropic polypeptide (GIP) agonist could exert beneficial metabolic control in diabetic mice which had been pre-treated with sodium-glucose-cotransporter-2 (SGLT2) inhibitor dapagliflozin (DAPA). High fat fed mice administered low dose streptozotocin (STZ) received vehicle, DAPA once-daily over 28 days, or DAPA once-daily for 14 days followed by (DAla(2))GIP once-daily for 14 days. Energy intake, body weight, glucose and insulin concentrations were measured at regular intervals. Glucose tolerance, insulin tolerance test, dual-energy X-ray absorptiometry (DEXA) and pancreatic histology were examined. Once-daily administration of (DAla(2))GIP for 14 days in high fat fed diabetic mice pre-treated with DAPA demonstrated significant decrease in body weight, blood glucose and increased insulin concentrations which were independent of changes in energy intake. Similarly, glucose tolerance, glucose-stimulated insulin secretion, insulin sensitivity and HOMA-ß were significantly enhanced in (DAla(2))GIP-treated mice. DEXA analysis revealed sustained percentage body fat loss with no changes in lean mass, bone mineral content and density. Pancreatic immunohistochemical analysis revealed decreased islet number and increases in islet area, beta cell area and pancreatic insulin content. The DAPA-induced increase in alpha cell area was also reversed. Additional acute in vitro and in vivo experiments confirmed that the impaired action of (DAla(2))GIP under hyperglycaemic-induced conditions was significantly reversed by DAPA treatment. These data demonstrate that (DAla(2))GIP can exert beneficial metabolic control in high fat fed diabetic mice pre-treated with DAPA. The results highlight possibility of a targeted and personalized approach using a GIP agonist and SGLT2 inhibitor for the treatment of type 2 diabetes.

Treatment of diabetic ketoacidosis using normalization of blood 3-hydroxybutyrate concentration as the endpoint of emergency management. A randomized controlled study.

OBJECTIVE: To compare the efficacy of an extended insulin regimen using correction of hyperketonemia as endpoint with a more conventional regimen in the treatment of diabetic ketoacidosis. RESEARCH DESIGN AND METHODS: A total of 22 patients admitted to a Belfast teaching hospital with clinical and biochemical features of diabetic ketoacidosis (pH < 7.25 and/or bicarbonate < 16 mmol/l) were randomized to either conventional or extended insulin regimens. In the conventional regimen, insulin was administered at 5 U/h until near-normoglycemia (blood glucose < or = 10 mmol/l) and then administered at a reduced rate until clinical recovery. In the extended regimen, administration of insulin at 5 U/h was continued beyond attainment of normoglycemia, until resolution of hyperketonemia (3-hydroxybutyrate < 0.5 mmol/l). Main outcome measures were 3-hydroxybutyrate and bicarbonate levels during the 24 h after attainment of near-normoglycemia. RESULTS: After near-normoglycemia, correction of hyperketonemia was achieved earlier with the extended treatment (5.9 +/- 0.8 vs. 21.8 +/- 3.4 h, P = 0.0004 [mean +/- SD]). The area under the curve of 3-hydroxybutyrate against time for 24 h after near-normoglycemia was reduced with the extended treatment (24.9 +/- 3.8 vs. 55.9 +/- 6.7 mmol.l-1.h-1, P = 0.001). These differences remained statistically significant after adjustment for higher baseline levels of 3-hydroxybutyrate at near-normoglycemia in the extended treatment group. Bicarbonate levels at 6 and 12 h after near-normoglycemia were not significantly different between groups. CONCLUSIONS: The extended insulin regimen, which was easy to implement at ward level, produced a more rapid resolution of ketosis than the conventional regimen.

Abnormalities of serum apo A1 containing lipoprotein particles in patients with primary biliary cirrhosis.

Patients with primary biliary cirrhosis (PBC) do not appear to have an increased risk of cardiovascular disease despite elevations in serum cholesterol. Recent evidence has pointed to LpA1 (an apo A1 containing particle which contains apo A1 but not apo A2) in protecting against atherosclerosis. The aim of this study was to investigate apo Al containing particles in the serum of patients with PBC. Lipids and apolipoproteins were measured in 31 patients with PBC (30 females) and 27 control subjects (26 females). Patients were divided into 3 groups: group 1 with bilirubin < 18 micromol/l (n = 17); group 2 with bilirubin > 18 micromol/l (n = 11); and group 3 with end stage liver disease (ESLD, n = 3). As expected group 1 and 2 patients had higher total cholesterol, HDL cholesterol and phospholipids than control subjects. Apo B and apo A1 concentrations were similar to control subjects. However, LpA1 was greatly increased: 0.96 g/l (0.60-1.50), median (range) in group 1 and 1.09 g/l (0.75-1.33) in group 2 versus 0.62 g/l (0.45-0.93) for controls both P < 0.005 and the percentage of total apo A1 in the LpA1 fraction was increased: 54.8% (37.9-63.4) in group 1 and 55.7% (47.8-73.7) in group 2 versus 36.8% (25.1-49.1) for controls, both P < 0.005. Apo A2 concentration was reduced in group 1 0.38 g/l (0.30-0.51) and group 2 0.31 g/l (0.14-0.58) versus controls 0.43 g/l (0.36-0.57), P < 0.05 and P < 0.005 respectively. Patients with ESLD had reduced HDL cholesterol, apo A1, LpA1 and apo A2 compared to controls. These results suggest that PBC is associated with an altered distribution of apo A1 favouring an increased concentration of the protective LpA-I particles. Increased LpA1 concentration may be one of the factors contributing to the paradoxically low incidence of atherosclerosis in PBC patients.

Rare apolipoprotein E variant identified in a patient with type III hyperlipidaemia.

We report a rare apolipoprotein E variant in an Irish female with Type III hyperlipidaemia who has the phenotype E2E1 as determined by isoelectric focusing. Sequence analysis of the apolipoprotein E gene from the proband and from four other family members, using DNA amplified by the polymerase chain reaction, demonstrated the presence of a point mutation in the common epsilon 2 allele with a G-->A transition at nucleotide 3791. This was confirmed by digestion with the restriction endonuclease TaqI, which cuts at a new site within the apolipoprotein E gene, created by the base change. This mutation results in a substitution of aspartic acid for glycine at position 127 of the mature protein. We believe this to be the first description of this apolipoprotein E variant in a family from the British Isles. The mutation appears to be 'recessive' with respect to the expression of Type III hyperlipidaemia, although it may be somewhat more potent in this regard than the parent epsilon 2 allele. The Type III hyperlipidaemia is responsive to treatment with diet and gemfibrozil.

Determinants of negative priming.

The negative priming task is widely used to investigate attentional inhibition. A critical review of the negative priming literature considers various parameters of the task (e.g., time course, relation to interference, level of occurence, and susceptibility to changes in task context). It takes into account life span data and the performance of patients diagnosed with schizophrenia. On these bases, the review suggests that negative priming can be produced by 2 mechanisms: memorial and inhibitory. With respect to inhibition, the review suggests that (a) there are 2 systems, one responsible for identity and the other for location information; and (b) inhibition is a flexible, postselection process operating to prevent recently rejected information from quickly regaining access to effectors, thus helping to establish coherence among selected thought and action streams.

Analogs of camptothecin.

Several compounds having portions of the camptothecin ring system were prepared. These compounds were screened against L1210 lymphoid leukemia with negative results. Two of the analogs which contained the pyridine and hydroxylactone D and E rings were also screened for inhibition of DNA and RNA syntheses in HeLa cells. Each of these analogs had decreased activity as compared with comptothecin and there was no degradation of DNA in the HeLa cells. This suggest that the D and E rings are not a sufficient requirement for camptothecin-like activity.

A controlled-attention view of working-memory capacity.

In 2 experiments the authors examined whether individual differences in working-memory (WM) capacity are related to attentional control. Experiment 1 tested high- and low-WM-span (high-span and low-span) participants in a prosaccade task, in which a visual cue appeared in the same location as a subsequent to-be-identified target letter, and in an antisaccade task, in which a target appeared opposite the cued location. Span groups identified targets equally well in the prosaccade task, reflecting equivalence in automatic orienting. However, low-span participants were slower and less accurate than high-span participants in the antisaccade task, reflecting differences in attentional control. Experiment 2 measured eye movements across a long antisaccade session. Low-span participants made slower and more erroneous saccades than did high-span participants. In both experiments, low-span participants performed poorly when task switching from antisaccade to prosaccade blocks. The findings support a controlled-attention view of WM capacity.

Inhibition of fibrin monomer polymerisation by myeloma immunoglobulin.

Myelomatosis was diagnosed in a 64 year old man on the basis of a serum paraprotein band (type IgG lambda, 42 g/l), plasma cell infiltration of bone marrow, and multiple lytic lesions evident on skull x ray picture. Blood specimens taken into plain glass tubes showed bulky gelatinous clot formation with minimal clot retraction. Coagulation tests were significantly abnormal with an increase in thrombin time, prothrombin time, and reptilase time. The possibility that the paraprotein was interfering with fibrin production was investigated. The rate of fibrin monomer polymerisation (measured turbidometrically) was reduced in patient plasma compared with control plasma. Although purified fibrin monomer prepared from the patient's fibrinogen polymerised normally, the addition of purified paraprotein caused a dose dependent reduction in the rate of polymerisation. These results suggest that the paraprotein was impairing fibrin formation by inhibiting fibrin monomer polymerisation. After chemotherapy the paraprotein concentration decreased and the coagulation results returned to normal.

Premonitory urges as "attentional tics" in Tourette's syndrome.

The author, a graduate student with Gilles de la Tourette's syndrome, proposes that pre-tic sensory experiences result from a specific attentional deficit. Based on his own introspective case study, the author argues that the premonitory urges that precede tics are not unique sensory events, but rather are manifestations of somatosensory hyperawareness which serves as the aversive stimulus toward which tics are purposively directed. An "attentional tic" theoretical framework for the study of Tourette's syndrome is suggested and discussed in reference to inhibitory theories of attention.

Determination of a diabetes control and complications trial-aligned HbA(1c) reference range in pregnancy.

A diabetes control and complications trial (DCCT)-aligned 95% inter-fractile reference range for glycated haemoglobin in non-diabetic pregnancy was determined as 4.1-5.9% (n=493; two-sided 90% confidence intervals around the lower and upper limits are 4.0-4.2% and 5.8-6.0%, respectively).

Dual mechanisms of negative priming.

Three experiments examined whether negative priming is a dually determined effect produced by inhibitory mechanisms and by a memorial process. Younger adults (Experiment 1) and older adults (Experiments 1-3) were tested in procedures that varied the likelihood of inducing retrieval of the prior trial. This was done by making test-trial target decoding difficult (Experiments 1 & 2) or by making prior information useful on some nonnegative priming trials (Experiment 3). Younger adults demonstrated negative priming under retrieval and nonretrieval conditions, with patterns of performance indicating different sources of negative priming effects. Older adults showed negative priming only under retrieval-inducing conditions, consistent with the view of deficient inhibitory mechanisms for older adults. The data suggest that contextual variables critically determine whether negative priming is largely due to inhibition or to episodic retrieval.

Inhibitory attentional mechanisms and aging.

Two experiments sought to elicit distractor suppression in older adults. Experiment 1 used a procedure that increased suppression in younger adults, thus creating a more sensitive measure of suppression in older adults. To compensate for older adults' slowed processing, Experiment 2 used a longer stimulus exposure duration. Neither experiment produced suppression in older adults; both experiments, however, included trial types that elicited parallel facilitatory effects for both age groups. Older adults thus seemed to process distractors but failed to engage inhibitory mechanisms in their rejection of distracting stimuli. Finally, both experiments tested the relationships among suppression, interference, and everyday cognitive failure. Neither experiment suggested relationships between reaction time effects and self-reported cognitive lapses. Results are discussed within L. Hasher and R. T. Zacks's (1988) attentional framework.

Working-memory capacity, proactive interference, and divided attention: limits on long-term memory retrieval.

Two experiments examined how individual differences in working-memory capacity (WM) relate to proactive interference (PI) susceptibility. We tested high and low WM-span participants in a PI-buildup task under single-task or dual-task ("load") conditions. In Experiment 1, a finger-tapping task was imposed during encoding and retrieval of each list; in Experiment 2, tapping was required during encoding or retrieval. In both experiments, low spans showed greater PI than did high spans under no load, but groups showed equivalent PI under divided attention. Load increased PI only for high spans, suggesting they use attention at encoding and retrieval to combat PI. In Experiment 2, only low spans showed a dual-task cost on List 1 memory, before PI built up. Results indicate a role for attentional processing, perhaps inhibitory in nature, at encoding and retrieval, and are discussed with respect to theories of WM and prefrontal cortex function.

Immunoglobulin-AST complex.

A case of AST-IgG complex presenting as an isolated AST elevation is described. Measurement of elevated serum AST activity is dependent upon the inclusion of pyridoxal 5-phosphate in the substrate.

Determination of the total protein and triglyceride content of human breast milk on the Synchron CX7 Delta analyser.

BACKGROUND: Premature babies have improved clinical outcomes when fed breast milk with a relatively high protein content. Since there was no convenient way of measuring the macronutrition of breast milk we used our routine laboratory pyrogallol red dye binding method for cerebrospinal fluid microprotein (MTP) and our routine method for serum triglyceride to determine the total protein and triglyceride content of human breast milk. METHODS: The total protein contents of whole and defatted breast milk samples, randomly collected from 115 nursing mothers, analysed using a pyrogallol red dye binding assay on a Synchron CX7 Delta analyser were compared with the total protein contents determined by dry combustion analysis. Triglyceride concentrations, determined on the Synchron CX7 Delta analyser were compared with their respective creamatocrits. RESULTS: Passing and Bablok regression analysis (95% confidence interval) gave the following regression equations: y = 5.98(5.48 to 6.56)x-1.32(-2.02 to -0.73) where y is whole milk MTP (g/L) and x is dry combustion analysis (g/100 g); y = 7.09 (6.54 to 7.78)x-2.44 (-3.46 to -1.67) where y is volume-corrected defatted milk MTP (g/L) and x is dry combustion analysis (g/100 g); y = 7.52 (6.86 to 8.24)x+0.90(-2.42 to 3.37) where y is whole milk triglyceride (mmol/L) and x is creamatocrit (%). CONCLUSION: The Synchron CX7 Delta total protein and triglyceride assays provide practical, rapid and reliable methods for the determination of the macronutrition in human milk.

Levels of peripheral blood cell DNA damage in insulin dependent diabetes mellitus human subjects.

Increased production of reactive oxygen species (ROS) in vivo can lead to cellular biomolecule damage. Such damage has been suggested to contribute to the pathogenesis of insulin dependent diabetes mellitus (IDDM). In this study, we used the alkaline comet assay to measure DNA damage (single-stranded DNA breaks and alkali-labile sites) in freshly isolated whole blood, lymphocytes, monocytes, and neutrophils from 23 subjects with IDDM and 32 age- and sex-matched controls. Analysis of the results showed elevated levels of DNA damage (expressed as % comet tail DNA) in the lymphocyte (4.10+/-0. 47, 3.22+/-0.22), monocyte (4.28+/-0.47, 3.49+/-0.18), and whole blood (4.93+/-0.51, 4.51+/-0.23) fractions from IDDM subjects compared to controls, respectively, but the increases observed were not statistically significant. However, we found significantly elevated basal levels of DNA damage in the neutrophil fraction (8. 38+/-0.64, 4.07+/-0.23; p<0.001, Mann-Whitney U test) in IDDM subjects compared to controls. Given these novel neutrophil findings, we extended the study to include a total of 50 IDDM subjects and 50 age- and sex-matched control subjects and determined basal levels of DNA damage in the neutrophils of all 100 subjects. We found significantly elevated mean levels of DNA damage (8.40+/-0.83, 4. 34+/-0.27; p<0.001, Mann-Whitney U test) in the neutrophils from the IDDM subjects when compared to controls. Our results show that even with acceptable glycaemic control there is a significantly elevated level of DNA damage within diabetic neutrophils in vivo.