What over 1,000,000 participants tell us about online research protocols

With the ever-increasing adoption of tools for online research, for the first time we have visibility on macro-level trends in research that were previously unattainable. However, until now this data has been siloed within company databases and unavailable to researchers. Between them, the online study creation and hosting tool Gorilla Experiment Builder and the recruitment platform Prolific hold metadata gleaned from millions of participants and over half a million studies. We analyzed a subset of this data (over 1 million participants and half a million studies) to reveal critical information about the current state of the online research landscape that researchers can use to inform their own study planning and execution. We analyzed this data to discover basic benchmarking statistics about online research that all researchers conducting their work online may be interested to know. In doing so, we identified insights related to: the typical study length, average completion rates within studies, the most frequent sample sizes, the most popular participant filters, and gross participant activity levels. We present this data in the hope that it can be used to inform research choices going forward and provide a snapshot of the current state of online research.

Selenium status of low-selenium area residents: Polish experience

The concentration of selenium (Se) in human organism varies widely between geographical areas depending on its content in soil and plants, dietary Se intake, bioavailability and retention, mineral interactions and other factors. The study includes healthy inhabitants of different regions of Poland; pregnant women, lactating women, children from 0 to 15 years of age and adults. Systematic determinations allow us to observe changes of the concentration of Se in time, which may be significant for developing preventive action. The results obtained confirm our thesis that Se concentration in the blood of the inhabitants of Poland depends on the region of the country. In recent years, in a considerable number of Polish inhabitants, the concentration of Se in blood plasma has been relatively low-about 50-55 microg/l, and the calculated daily dietary intake about 30-40 microg/day. The low levels of the element in the blood and urine are probably due to its deficiency in the diet.

Comparison of gravimetry and hydrolysis/derivatization/gas chromatography-mass spectrometry for quantitative analysis of fat from standard reference infant formula powder using supercritical fluid extraction

This paper describes a comparative study of the gravimetric versus hydrolysis/derivatization/gas chromatography-mass spectrometry determination of fat in infant formula. Fat was extracted using supercritical carbon dioxide modified with a small amount of ethanol, the extract was weighed, and the total fat was determined gravimetrically. Subsequently, another sample of the supercritical fluid fat extract was hydrolyzed to yield free fatty acids, which were converted to their methyl ester derivatives (FAMEs). Quantification was performed by GC-MS. NIST Standard Reference Material (SRM-1846) was used to validate both fat determination methods. Results showed that the gravimetric average percent fat was 26.86%, whereas the GC-MS method yielded 24.64%. Some peaks were detected in the ion chromatogram from the GC-MS that were identified as nonfatty acids such as aldehydes, which may account for the higher percentage fat measured as weight of extract rather than measured as FAMEs expressed as triglycerides.

Tay-Sachs screening in the Jewish Ashkenazi population: DNA testing is the preferred procedure

A unique screening program for the identification of Tay-Sachs Disease (TSD) heterozygotes has been performed in the tradi- tional Orthodox Ashkenazi Jewish (AJ) community since 1983. In recent years the program has utilized the biochemical assay for the determination of hexosaminidase A levels by the heat inactivation technique as well as by direct DNA analysis. The three mutations which were analyzed were those that have been shown to be prevalent among AJ TSD patients and carriers, namely the four nucleotide insertion mutation in exon 11 (1278+TATC), the splice mutation at the 5' end of intron 12 (1421+1g-->c), and the adult mutation, a Gly(269)-->Ser substitution in exon 5 (G269S). A total of 103,133 individuals were tested by biochemical analysis, and 38,197 of them were also assayed by DNA testing. Furthermore, 151 chromosomes from TSD patients or obligate heterozygotes were subjected to DNA analysis for one of the three mutations. DNA testing of the latter identified one of the three AJ mutations in every case, predicting a very high detection rate of heterozygotes in this community by this method. By contrast, the sensitivity of the enzyme assay ranged from 93.1% to 99.1% depending on the exclusion (inclusion) of inconclusive results as positive, while the specificity ranged from 88.1% to 98.8% depending on the inclusion (exclusion) of inconclusive results as positive. Our results strongly support the use of DNA testing alone as the most cost-effective and efficient approach to carrier screening for TSD in individuals of confirmed Ashkenazi Jewish ancestry.

Diphtheria toxin A gene-mediated HIV-1 protection of cord blood-derived T cells in the SCID-hu mouse model

The reconstitutive potential of CD34+-derived cord blood (CB) cells, transduced with a regulated diphtheria toxin A (DT-A) chain gene, was examined in SCID-hu mice harboring a conjoint organ composed of human thymus and liver (thy/liv). The DT-A-transduced cells, injected directly into the thy/liv organ, showed the same engraftment potential as control CB cells transduced with the non-DT-A parental vector. CB cells, distinguishable from the thy/liv cells by the HLA marker B7, were preferentially maintained in ex vivo culture. In the thy/liv organ, the engrafted CB cells represented >80% of the total cells. A majority of cells (>70%) in the thy/liv organ were also CD4+CD8+, as would be expected of maturing thymocytes. The incidence of double-positive cells was highest at 44 days (compared with 30 days and 80 days) after injection of CB cells. This suggested that a minimum time was required to achieve optimal proliferation of cells in the thy/liv organ but that, at later times, all of the early cells had matured. Thus, the population used for engraftment contained early cells but not self-renewing cells. The double-positive cells matured rapidly into single-positive cells (either CD4+ or CD8+) when placed in ex vivo culture. Marked cells (neo+) could readily be detected in the thy/liv-derived cells. The cells transduced with DT-A showed long-term protection in ex vivo culture against HIV T lymphotropic isolate NL4-3. This study shows that DT-A-transduced cells had no apparent disadvantage in engraftment of the thy/liv organ and did not have any toxic effects in vivo. Such cells were protected against HIV infection even when challenged more than 2 months after transduction and after a 44-day engraftment period in the thy/liv mice. These data support the feasibility of toxin gene therapy as a strategy for HIV infection.

Heterozygosity for Tay-Sachs disease in non-Jewish Americans with ancestry from Ireland or Great Britain

We performed a genetic epidemiological analysis of American non-Jewish people with ancestry from Ireland or Great Britain with regard to heterozgosity for Tay-Sachs disease (TSD). This study was prompted by a recent report that the frequency of heterozygosity for TSD among Irish Americans was 1 in 8, a frequency much higher than that recognised for any other population group. We identified 19 of 576 (3.3%) people of Irish background as TSD heterozygotes by the standard thermolability assay for beta-hexosaminidase A (Hex A) activity. Three of 289 people of non-Irish British Isles background (1%) were also identified as heterozygotes by biochemical testing. Specimens from the biochemically identified Irish heterozygotes were analysed for seven different Hex A alpha subunit gene mutations; three (15.8%) had a lethal +1 IVS-9 G to A mutation, previously noted to be a common mutation among TSD heterozygotes of Irish ancestry. Eight of 19 (42.1%) had one of two benign or pseudodeficiency mutations, and no mutation was found in 42.1% of the heterozygotes analysed. These data indicate that non-Jewish Americans with Irish background have a significantly increased frequency of heterozygosity at the Hex A alpha subunit gene locus, but that approximately 42% of the biochemically ascertained heterozygotes have clinically benign mutations. A pseudodeficiency mutation was identified in one of the three TSD heterozygotes of non-Irish British Isles background; no mutations were found in the other two. The data allow for a frequency estimate of deleterious alleles for TSD among Irish Americans of 1 in 192 to 1 in 52. Non-Jewish Americans with ancestry from Great Britain have a minimal, if any, increase in rate of heterozygosity at the TSD gene locus relative to the general population.

Increased urinary nitrite excretion in children with minimal change nephrotic syndrome

OBJECTIVE

We tested the hypothesis that nitric oxide synthesis by the kidney is increased in children with primary nephrotic syndrome.

METHODS

We examined the urinary excretion of nitrite, a stable metabolite of nitric oxide, using the Griess reaction, in children with nephrotic syndrome.

RESULTS

In comparison with healthy children, patients with minimal change nephrotic syndrome had increased urinary nitrite excretion regardless of whether the disease was in relapse or remission (p < 0.025). In contrast, urinary nitrite excretion was similar in control subjects and patients with focal segmental glomerulosclerosis or IgA nephropathy.

CONCLUSION

These findings indicate that measurement of urinary nitrite excretion may be a useful test to help discriminate between minimal change nephrotic syndrome and focal segmental glomerulosclerosis in children with idiopathic nephrotic syndrome.

Optimization of gene transfer using cationic lipids in cell lines and primary human CD4+ and CD34+ hematopoietic cells

Cationic lipids offer several advantages for gene delivery, both in vitro and in vivo. However, high-efficiency gene transfer has been demonstrated only for limited cell types. Here, we examine the level of expression of a luciferase reporter gene, delivered using cationic lipids, in both cell lines and primary human cells including peripheral blood mononuclear cells and CD34(+)-enriched hematopoietic cells. Variables shown to affect the efficiency of gene expression included the type of lipid, the amounts of DNA and lipid, the day of assay following transfection, the media used for lipid:DNA complex formation, the cell number, the promoter driving expression of the reporter gene and the physiological state of the cells (e.g., whether or not cells were differentiated). The maximal luciferase expression observed with the primary cells was one to two orders of magnitude lower than that seen in cell lines. Further studies, possibly involving altering the growth conditions for the cells, or using episomal vectors that will allow extrachromosomal maintenance of the DNA, are required to improve the level of transgene expression in the primary human cell types used here.

An intraventricular axial flow blood pump integrated with a bearing purge system

The future development of implantable axial flow blood pumps must address two major issues: mechanically induced hemolysis and shaft seal reliability. The recent revisions to our miniature intraventricular axial flow left ventricular assist device (LVAD) were aimed particularly at addressing these concerns. To improve hemocompatibility, a new impeller has been designed according to the following criteria: 1) gradual pressure rise along the blade chord; 2) minimized local fluid acceleration to prevent cavitation; 3) minimum surface roughness; and 4) radius edges. Subsequent in vitro hemolysis tests conducted with bovine and ovine blood have demonstrated very low hemolysis (normalized index of hemolysis = 0.0051 +/- 0.0047 g/100 L) with this new impeller design. To address the need for a reliable seal, we have developed a purged seal system consisting of a miniature lip seal and ceramic pressure groove journal bearing that also acts as a purge pump. Several spiral grooves formed on the bearing surface provide viscous pumping of the purge fluid, generating more than 3,000 mmHg at 10,000 rpm. This purge flow flushes the lip seal and prevents blood backflow into the bearing. We have found this purge pump to offer several advantages because it is simple, compact, durable, does not require separate actuation, and offers a wide range of flow, depending upon the groove design. In vivo animal tests demonstrated the potential of the purged seal system.

An unusual genotype in an Ashkenazi Jewish patient with Tay-Sachs disease

The Ashkenazi Jewish population is enriched for carriers of a fatal form of Tay-Sachs disease, a recessive inherited disorder caused by mutations in the alpha-chain of the lysosomal enzyme beta-hexosaminidase A. Approximately 20% of the Ashkenazi carriers harbor a splice junction defect while about 78% bear a 4 base pair (bp) insertion. However, the Ashkenazi Jewish patient used in the original description of the 4 bp insertion carried this lesion in only 1 allele and was negative for the splice junction mutation. We cloned the insertion negative allele and by sequence analysis of the exons found a point mutation in exon 11 that results in substitution of Trp392 with a premature termination codon. Nine Ashkenazi Jewish carriers that tested negative for the major and minor mutations as well as for a lesion causing an adult form of Tay-Sachs disease did not carry the base change defect, suggesting that it may be a recent and/or rare mutation. This finding also indicates that screening the Ashkenazi population solely by recombinant DNA methods for the splice junction, 4 bp insertion, and adult mutations may result in occasional false negatives.

Distribution of three alpha-chain beta-hexosaminidase A mutations among Tay-Sachs carriers

DNA from 176 carriers of the Tay-Sachs gene was tested for the presence of the three mutations most commonly found among Ashkenazi Jews: the so-called insertion, splice junction, and adult mutations. Among 148 Ashkenazi Jews tested, 108 had the insertion mutation, 26 had the splice junction mutation, five had the adult mutation, and nine had none of the three. Among 28 non-Jewish carriers tested, most of whom were obligate carriers, four had the insertion mutation, one had the adult mutation, and the remaining 23 had none of the three.