Kidney function and retinol status in type 2 diabetes mellitus patients

Kidneys play an important role in retinol turnover. We postulated that retinol homeostasis is disturbed in diabetic nephropathy. The aim of this research was to study the effect of kidney impairment on urinary excretion and on serum concentrations of retinol in type 2 diabetes mellitus patients. For this purpose, 41 type 2 diabetes patients and 9 sex -and age-matched healthy subjects were enrolled. Serum and urinary retinol and retinol-binding protein (RBP) were assessed by high-pressure liquid chromatography and enzyme-linked immunosorbent assay, respectively. The study showed that 17 out of 41 diabetic patients (41.5%) and none of the controls excreted retinol in urine (P < 0.02). Retinol excretion in the urine in these patients was 1.5-fold more prevalent than hypercreatininemia. Urinary retinol significantly correlated with clinically diagnosed nephropathy (P = 0.02). All but one of the patients with hypercreatininemia excreted retinol in the urine. Serum retinol and RBP in patients with hypercreatininemia were higher than in controls (P < 0.002). Values of urinary retinol, unlike urinary RBP, albumin and total protein, did not overlap between patients and controls. Our results indicate that (i) urinary retinol is a specific sign of tubular damage in type 2 diabetic patients and (ii) urinary retinol enables a more clear-cut identification of proximal tubule dysfunction in type 2 diabetes patients than urinary RBP or albumin.     

Trends in Evolving Technologies in the Operating Room of the Future

Technology has much to offer the surgical disciplines. However, teamwork, open communication, and a willingness to adapt and adopt new skills and processes are critical to achieving improved clinical outcomes.     

Schizophrenia-like neurophysiological abnormalities in 22q11.2 deletion syndrome and their association to COMT and PRODH genotypes

22q11.2 deletion syndrome (22q11.2DS) is a common genetic risk factor for the development of schizophrenia. We investigated two neurophysiological endophenotypes of schizophrenia – P50 sensory gating and mismatch negativity in 22q11.2DS subject and evaluated their association with catechol O-methyltransferase (COMT) and proline dehydrogenase (PRODH) genetic variants. We also assessed the association of neurophysiological measures with schizophrenia-like symptomatology in 22q11.2DS. Fifty-nine subjects, 41 with 22q11.2DS and 18 typically developing controls, participated in the study. The participants with 22q11.2DS were genotyped for the COMT Val¹⁵⁸Met (rs4680) and PRODH Gln¹⁹Pro (rs2008720) and Arg¹⁸⁵Trp (rs4819756) polymorphisms. Following psychiatric evaluation, all the participants underwent neurophysiological recordings and executive function assessment. The 22q11.2DS group showed poorer sensory gating of the P50 response than the controls. Within the 22q11.2DS group, the COMT Met allele was associated with poorer sensory gating, while both the COMT Met allele and the PRODH Pro-Arg haplotype were associated with smaller mismatch negativity amplitudes. Smaller mismatch negativity amplitudes predicted greater impairment of executive functions and greater severity of schizophrenia-like negative symptoms in 22q11.2DS. The current study demonstrates that sensory gating impairments that are typical of schizophrenia are found in 22q11.2DS subjects. Our results further suggest that COMT and PRODH genetic variations contribute to sensory gating and mismatch negativity schizophrenia-like impairments in 22q11.2DS, possibly via dopaminergic/glutamatergic networks. The associations of mismatch negativity impairments with increased severity of schizophrenia-like negative symptoms and poorer executive functions performance in our 22q11.2DS sample suggest that mismatch negativity is a potential endophenotype for schizophrenia in 22q11.2DS.     

Quantitative Detection of Thrombin Activity in an Ischemic Stroke Model

Thrombin, a central factor in thrombogenesis, affects cells in the brain through protease activated receptors. Low levels of thrombin activity are neuroprotective while higher levels are deleterious, and we have therefore developed a new method for its direct quantitative measurement in brain slices following stroke. Thrombin activity was measured by a fluorescent substrate on fresh coronal slices taken from the ipsilateral and contralateral hemispheres 24–72 h following permanent right middle cerebral artery occlusion. Prolyl endopeptidase and aminopeptidases were inhibited as a critical step to insure the specificity of the assay for thrombin detection. Infarct volume was assessed using TTC staining. Thrombin activity in the right ischemic hemisphere was significantly higher compared to the contralateral hemisphere (32?±?6 and 27?±?10 mU/ml, mean?±?SE in the two most affected slices from the ischemic hemisphere vs. 21?±?6 and 8?±?2 mU/ml in corresponding contralateral slices; p?<?0.05). Thrombin levels in the ischemic and contralateral hemispheres were significantly higher compared to healthy control mice and were above the range known to be protective to brain cells. A significant correlation was found between thrombin activity in the ischemic hemisphere and the infarct volume. Results of studies based on this method may translate into potential thrombin based therapies.     

Identification of protein complexes in detergent-resistant membranes of Plasmodium falciparum schizonts

Merozoite surface proteins of the human malaria parasite Plasmodium falciparum are involved in initial contact with target erythrocytes, a process that begins a cascade of events required for successful invasion of these cells. In order to identify complexes that may play a role in invasion we purified detergent-resistant membranes (DRMs), known to be enriched in merozoite surface proteins, and used blue native-polyacrylamide gel electrophoresis (BN-PAGE) to isolate high molecular weight complexes for identification by mass spectrometry. Sixty-two proteins were detected and these mostly belonged to expected DRM proteins classes including GPI-anchored, multi-membrane spanning and rhoptry proteins. Proteins from seven known complexes were identified including MSP-1/7, the low (RAP1/2 and RAP1/3), and high (RhopH1/H2/H3) molecular weight rhoptry complexes, and the invasion motor complex (GAP45/GAP50/myosinA). Remarkably, a large proportion of identified spectra were derived from only 4 proteins: the GPI-anchored proteins MSP-1 and Pf92, the putative GPI-anchored protein Pf113 and RAP-1, the core component of the two RAP complexes. Each of these proteins predominated in high molecular weight species suggesting their aggregation in much larger complexes than anticipated. To demonstrate that the procedure had isolated novel complexes we focussed on MSP-1, which predominated as a distinct species at approximately 500 kDa by BN-PAGE, approximately twice its expected size. Chemical cross-linking supports the existence of a stable MSP-1 oligomer of approximately 500 kDa, probably comprising a highly stable homodimeric species. Our observations also suggests that oligomerization of MSP-1 is likely to occur outside the C-terminal epidermal growth factor (EGF)-like domains. Confirmation of MSP-1 oligomerization, together with the isolation of a number of known complexes by BN-PAGE, makes it highly likely that novel interactions occur amongst members of this proteome.     

Aggregation of qualitative studies--From theory to practice: Patient priorities and family medicine/general practice evaluations

OBJECTIVE: Aggregation (i.e., meta-ethnography or meta-synthesis) of qualitative studies remains relatively rare and controversial. We have attempted this procedure within an investigation of patient priorities and evaluations of primary care in order to triangulate an instrument development process as well as explore associated dilemmas. METHODS: The procedures included a literature search of qualitative research on patient priorities and evaluations and creation of a framework for quality assessment of retrieved papers. The tool for the evaluation of quality in qualitative studies was piloted, refined, and applied to the retrieved literature. The articles were equally distributed between two teams in random fashion, and inter-rater agreement calculated. Finally, we formulated and applied a strategy for aggregation of data from included papers that allowed comparison to a systematic review of quantitative studies on the topic. RESULTS: Thirty-seven articles met inclusion criteria. Twenty-four of these articles were of sufficient quality to be included in the qualitative aggregation. Inter-rater agreement ranged from 0.22 to 0.77 and 0.38 to 0.60 for pair and assessor comparisons, respectively. The aggregation strategy enabled synthesis within sub-categories of the heterogeneous papers. CONCLUSIONS: We have devised a modestly reliable instrument to assess the quality of qualitative work. The procedure for quality assessment and aggregation appears to be both feasible and potentially useful, though both theoretical and practical problems underline the need for further refinement prior to widespread utilization of this approach. PRACTICE IMPLICATIONS: An instrument to assess the quality of qualitative work within the context of aggregation efforts is described. Calculating inter-rater reliability in this framework can support future quality assessments. A method of breaking a heterogeneous collection of included papers into sub-categories to enable aggregation of qualitative studies is applied and demonstrates its feasibility and potential usefulness.     

CpG DNA stimulates autoreactive immature B cells in the bone marrow

Polyclonal activation of developing B cells is an injurious process, because most of these cells are nontolerant and express autoreactive receptors. CpG DNA is a polyclonal activator of mature B cells, but its effect on developing B cells is unclear. We tested whether developing, nontolerant B cells are responsive to mitogenic stimulation by CpG DNA and whether such a stimulus can interfere with the establishment of central tolerance. We found that developing B cells express Toll-like receptor 9 and undergo a polyclonal response to CpG DNA stimulation, as revealed by proliferation and differentiation to antibody-producing cells. In vitro and ex vivo experiments revealed that stimulation with CpG DNA protects immature B cells from negative selection imposed by apoptosis and receptor editing and results in the production of autoantibodies. Finally, we found that in vivo administration of CpG DNA activates immature B cells in the bone marrow and suppresses the expression of recombination-activating genes in a mouse model of central tolerance and receptor editing. These results suggest that mitogenic signals provided by CpG DNA stimulate nontolerant immature B cells in the bone marrow and have the potential to interfere with central tolerance.     

The burden of severe hypoglycemia in type 1 diabetes

Aims: Approximately 1.25 million people in the US have type 1 diabetes mellitus (T1DM), a chronic metabolic disease that develops from the body’s inability to produce insulin, and requires life-long insulin therapy. Poor insulin adherence may cause severe hypoglycemia (SHO), leading to hospitalization and long-term complications; these, in turn, drive up costs of SHO and T1DM overall. This study’s objective was to estimate the prevalence and costs of SHO-related hospitalizations and their additional longer-term impacts on patients with T1DM using basal-bolus insulin.

Methods: Using Truven MarketScan claims, we identified adult T1DM patients using basal-bolus insulin regimens who were hospitalized for SHO (inpatient SHO patients) during 2010–2015. Two comparison groups were defined: those with outpatient SHO-related encounters only, including emergency department (ED) visits without hospitalization (outpatient SHO patients), and those with no SHO- or acute hyperglycemia-related events (comparison patients). Lengths of stay and SHO-related hospitalization costs were estimated and propensity score and inverse probability weighting methods were used to adjust for baseline differences across the groups to evaluate longer-term impacts.

Results: We identified 8,734 patients, of which 4.2% experienced at least one SHO-related hospitalization. Among those who experienced SHO (i.e. of those in the inpatient and outpatient SHO groups), 31% experienced at least one SHO-related hospitalization, while 9% were treated in the ED without subsequent hospitalization. Approximately 79% of patients were admitted directly to the hospital; the remainder were first assessed or treated in the ED. The inpatient SHO patients stayed in the hospital, including time in the ED, for 1.7 days and incurred $3551 in costs. About one-third of patients were hospitalized again for SHO. Inpatient SHO patients incurred significantly higher monthly costs after their initial SHO-related hospitalization than patients in the two other groups ($2084 vs $1313 and $1372), corresponding to 59% or 52% higher monthly costs for inpatient SHO patients.

Limitations: These analyses excluded patients who did not seek ED or hospital care when faced with SHO; events may have been miscoded; and we were not able to account for clinical characteristics associated with SHO, such as insulin dose and duration of diabetes, or unmeasured confounders.

Conclusions: The burden associated with SHO is not negligible. About 4% of T1DM patients using basal-bolus insulin regimens are hospitalized at least once due to SHO. Not only did those patients incur the costs of their SHO hospitalization, but they also incur red at least $712 (52%) more in costs per month after their hospitalization than outpatient SHO or comparison patients. Reducing SHO events can help decrease the burden associated with SHO among patients with T1DM.     

Effect of Rivastigmine on Mobility of Patients with Higher-Level Gait Disorder: A Pilot Exploratory Study

Background

Higher-level gait disorder (HLGD) in older adults is characterized by postural instability, stepping dysrhythmicity, recurrent falls and progressive immobility. Cognitive impairments are frequently associated with HLGD.

Objectives

The aim of this study was to compare gait and cognitive performance before and after the use of rivastigmine in patients with HLGD, free from cognitive impairment or Parkinsonism.

Methods

Fifteen non-demented patients with HLGD (age 79.2 ± 5.9 years; 11 women; Mini-Mental State Examination [MMSE] 28.3 ± 1.4) received escalating doses of rivastigmine for 12 weeks in an open-label, pilot study. They were assessed before and after treatment (week 0 and week 12), and after a 4-week washout period (week 16). Assessments included the Mindstreams computerized neuropsychological battery, Activities-specific Balance Confidence Scale, State-Trait Anxiety Inventory, Geriatric Depression Scale, Timed Up and Go (TUG) test, gait speed and stride time variability. One-way multiple analysis of variance tests for repeated measures were used, and Pillai’s trace test was considered as robust to investigate significant differences.

Results

The mean dose of rivastigmine during the 8–12 week period was 5.1 ± 2.3 mg/day. A positive effect was observed on the Mindstreams memory subscale and anxiety scores [Pillai’s trace: F(6,724) = 0.508, p = 0.010; and F(7,792) = 0.545, p = 0.006, respectively, over the course of the study] as well as on mobility (TUG test) [Pillai’s trace: F(4,863) = 0.448; p = 0.028], whereas gait speed and stride time variability did not change.

Conclusions

The use of relatively low-dose rivastigmine did not affect gait speed and stride time variability; however, the general mobility and anxiety were improved. These preliminary results warrant a larger, randomized, placebo-controlled study.