A handheld luminometer with sub-attomole limit of detection for distributed applications in global health

Luminescence is ubiquitous in biology research and medicine. Conceptually simple, the detection of luminescence nonetheless faces technical challenges because relevant signals can exhibit exceptionally low radiant power densities. Although low light detection is well-established in centralized laboratory settings, the cost, size, and environmental requirements of high-performance benchtop luminometers are not compatible with geographically-distributed global health studies or resource-constrained settings. Here we present the design and application of a ~$700 US handheld, battery-powered luminometer with performance on par with high-end benchtop instruments. By pairing robust and inexpensive Silicon Photomultiplier (SiPM) sensors with a low-profile shutter system, our design compensates for sensor non-idealities and thermal drift, achieving a limit of detection of 1.6E-19 moles of firefly luciferase. Using these devices, we performed two pilot cross-sectional serology studies to assess sars-cov-2 antibody levels: a cohort in the United States, as well as a field study in Bangladesh. Results from both studies were consistent with previous work and demonstrate the device's suitability for distributed applications in global health.

Evolving etiologies, comorbidities, survival, and costs of care in adult encephalitis

Encephalitis is a central nervous system disorder, often caused by infectious agents or aberrant immune responses. We investigated causes, comorbidities, costs, and outcomes of encephalitis in a population-based cohort. ICD-10 codes corresponding to encephalitis were used to identify health services records for all adults from 2004 to 2019. Data were cross-validated for identified diagnoses based on laboratory confirmation using univariate and multivariate statistical analyses. We identified persons with a diagnosis of encephalitis and abnormal cerebrospinal fluid (CSF) results (n = 581) in whom viral genome was detected (n = 315) in a population of 3.2 million adults from 2004 to 2019. Viral genome-positive CSF samples included HSV-1 (n = 133), VZV (n = 116), HSV-2 (n = 34), enterovirus (n = 4), EBV (n = 5), and CMV (n = 3) with the remaining viruses included JCV (n = 12) and HHV-6 (n = 1). The mean Charlson Comorbidity Index (2.0) and mortality rate (37.6%) were significantly higher in the CSF viral genome-negative encephalitis group although the mean costs of care were significantly higher for the CSF viral genome-positive group. Cumulative incidence rates showed increased CSF VZV detection in persons with encephalitis, which predominated in persons over 65 years with a higher mean Charlson index. We detected HSV-2 and VZV more frequently in CSF from encephalitis cases with greater material-social deprivation. The mean costs of care were significantly greater for HSV-1 encephalitis group. Encephalitis remains an important cause of neurological disability and death with a viral etiology in 54.2% of affected adults accompanied by substantial costs of care and mortality. Virus-associated encephalitis is evolving with increased VZV detection, especially in older persons.

Human pegivirus viremia in HCV/HIV co-infected patients: Direct acting antivirals exert anti-pegivirus effects

BACKGROUND

Human pegivirus (HPgV) is a single-stranded RNA virus​ that is closely related to hepatitis C virus (HCV)​. HPgV has also been shown to infect patients with human immunodeficiency virus (HIV). The mechanisms and disease outcomes of HPgV infections are largely unknown, although it has been implicated in both cancer and neurological diseases. There are no established therapies for HPgV.

OBJECTIVES

To estimate the prevalence of HPgV in a cohort of HCV/HIV co-infected patients undergoing treatment for HCV with direct acting antivirals (DAA) and investigate the effect of DAA therapy on HPgV infection.

STUDY DESIGN

RNA was extracted from plasma samples collected at time points before, during, and after DAA. HPgV RNA abundance was quantified by droplet digital PCR assays targeting the NS5A and 5'UTR domains and confirmed by RT-qPCR. Clinical, demographic and treatment data were analysed.

RESULTS

HPgV RNA was detected and quantified in 26 of 100 patients' plasma (26%) before starting DAA. Patients with detectable HPgV were more likely to be male, had higher peak HIV plasma levels, and a history of injection drug use. Patients receiving sofosbuvir/ledipasvir (n = 9) displayed significantly lower HPgV levels at time of DAA completion and had lower post-DAA HPgV rebound​ levels compared to patients receiving sofosbuvir/velpatasvir (n = 11) although both regimens significantly reduced viremia directly following DAA completion. Sustained suppression of HPgV was ​also observed among patients (n = 2) receiving pegylated-interferon.

CONCLUSIONS

HPgV RNA ​was frequently detected in HCV/HIV co-infected patients and ​was​ supressed by DAA and pegylated interferon therapies with sofosbuvir-ledipasvir showing greatest antiviral activity. These findings suggest potential treatment strategies for HPgV infections​.

Screening of potential novel candidate genes in schwannomatosis patients

Schwannomatosis comprises a group of hereditary tumor predisposition syndromes characterized by, usually benign, multiple nerve sheath tumors, which frequently cause severe pain that does not typically respond to drug treatments. The most common schwannomatosis‐associated gene is NF2, but SMARCB1 and LZTR1 are also associated. There are still many cases in which no pathogenic variants (PVs) have been identified, suggesting the existence of as yet unidentified genetic risk factors. In this study, we performed extended genetic screening of 75 unrelated schwannomatosis patients without identified germline PVs in NF2, LZTR1, or SMARCB1. Screening of the coding region of DGCR8, COQ6, CDKN2A, and CDKN2B was carried out, based on previous reports that point to these genes as potential candidate genes for schwannomatosis. Deletions or duplications in CDKN2A, CDKN2B, and adjacent chromosome 9 region were assessed by multiplex ligation‐dependent probe amplification analysis. Sequencing analysis of a patient with multiple schwannomas and melanomas identified a novel duplication in the coding region of CDKN2A, disrupting both p14ARF and p16INK4a. Our results suggest that none of these genes are major contributors to schwannomatosis risk but the possibility remains that they may have a role in more complex mechanisms for tumor predisposition.

Population estimate and rate of increase of southern right whales Eubalaena australis in southeastern Australia

In Australian waters, southern right whales Eubalaena australis form 2 genetically distinct populations that have shown contrasting patterns of recovery since whaling ceased: a western population in South Australia and Western Australia and an eastern population in southeastern Australia (Tasmania, Victoria and New South Wales). Here, we provide an abundance estimate derived from a breeding female superpopulation mark-recapture model for the southeastern southern right whale population. The population comprises 268 individuals (68 breeding females) and has increased at a rate of 4.7% per annum between 1996 and 2017. There has been no significant change in the annual abundance of mother-calf pairs sighted at the only calving ground (Logans Beach in Victoria) over the last 3 decades. The total number of southern right whales (i.e. all adults and calves) using the southeastern Australian coastline has increased by 7% since 1985. Unlike the population estimate (which was restricted to breeding females sighted prior to the post-breeding southward migration), this estimate is likely to include transiting whales from the southwestern population. The theoretical population model predicts 19 breeding females at Logans Beach in 2018 and 28 in 2028; the actual number of breeding females, as of 2018, is 14. This study provides the first complete estimate of population size and rate of increase of southern right whales along the southeastern Australian coastline. This knowledge is critical for assessing population status and recovery of southern right whales in Australia. It provides a basis for monitoring persistence and responses of the population to environmental stressors.

Impairment of Nrf2- and Nitrergic-Mediated Gastrointestinal Motility in an MPTP Mouse Model of Parkinson's Disease

BACKGROUND

Gastrointestinal (GI) motility dysfunction is the most common non-motor symptom of Parkinson's disease (PD). Studies have indicated that GI motility functions are impaired before the onset of PD.

AIMS

To investigate the underlying mechanism of PD-induced GI dysmotility in MPTP (1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine)-induced animal model.

METHODS

C57BL/6 mice were administered with or without a selective dopamine neurotoxin, MPTP, to induce parkinsonian symptoms. In addition to in vivo studies, in vitro experiments were also conducted in colon specimens using l-methyl-4-phenylpyridinium (MPP+), a metabolic product of MPTP. Gastric emptying, colon motility, nitrergic relaxation, and western blot experiments were performed as reported.

RESULTS

MPTP-induced PD mice showed decreased expression of nuclear factor erythroid 2-related factor (Nrf2) and its target phase II genes in gastric and colon neuromuscular tissues. Decreased levels of tetrahydrobiopterin (BH4, a critical cofactor for nNOS dimerization) associated with uncoupling of nNOS in gastric and colon tissues exposed to MPTP. Impaired enteric nitrergic system led to delayed gastric emptying and slower colonic motility compared to the control mice. In vitro results in colon specimens confirm that activation of Nrf2 restored MPP+-induced suppression of alpha-synuclein, tyrosine hydroxylase (TH), Nrf2, and heme oxygenase-1. In vitro exposure to L-NAME [N(w)-nitro-L-arginine methyl ester], a NOS synthase inhibitor, reduced protein expression of TH in colon tissue homogenates.

CONCLUSIONS

Loss of Nrf2/BH4/nNOS expression in PD impairs antioxidant gene expression, which deregulates NO synthesis, thereby contributing to the development of GI dysmotility and constipation. Nitric oxide appears to be important to maintain dopamine synthesis in the colon.

Prevention and control of carbapenemase-producing organisms at a regional burns centre

In many parts of the world, carbapenemase-producing organisms (CPOs) are endemic. The transfer of medical patients from such countries to the UK requires us to have control systems in place to avoid onward transmission. This report describes the experience of a regional burns centre challenged by its first four cases of CPO in two separate incidents. Key learning from our experience was the importance of CPOs being considered in empirical antibiotics for any patient from an endemic area. Using contact plates, we demonstrated high bacterial counts after cleaning and we describe a terminal cleaning strategy along with the importance of continuing staff engagement and education.

Ethnic Residential Segregation: A Multilevel, Multigroup, Multiscale Approach Exemplified by London in 2011

We develop and apply a multilevel modeling approach that is simultaneously capable of assessing multigroup and multiscale segregation in the presence of substantial stochastic variation that accompanies ethnicity rates based on small absolute counts. Bayesian MCMC estimation of a log-normal Poisson model allows the calculation of the variance estimates of the degree of segregation in a single overall model, and credible intervals are obtained to provide a measure of uncertainty around those estimates. The procedure partitions the variance at different levels and implicitly models the dependency (or autocorrelation) at each spatial scale below the topmost one. Substantively, we apply the model to 2011 census data for London, one of the world's most ethnically diverse cities. We find that the degree of segregation depends both on scale and group.

Performing slow vital capacity in older people with and without cognitive impairment--is it useful?

BACKGROUND

most patients with moderate cognitive impairment are unable to perform forced spirometry. It has been suggested that slow vital capacity (SVC) is easier to perform than forced vital capacity (FVC) because it requires less understanding and co-ordination. We conducted a study to determine whether that assertion is correct.

METHODS

we studied 83 inpatients, mean age 83 years (range 67-95, 51 female). They had measurements made of FVC, SVC and the Mini-Mental State Examination (MMSE). The spirometry was conducted using the European Respiratory Society/American Thoracic Society standards.

RESULTS

of the 83 subjects, 38 were able to do both FVC and SVC and 32 were unable to do either. The overall concordance was 84%. Twelve were able to do SVC but not FVC (eight due to excessive cough, two due to weakness and two had an MMSE < 24 with poor co-ordination). An inability to do neither FVC nor SVC was predicted by an MMSE < 24/30 (P < 0.0001) with a sensitivity of 88% and specificity of 67%.

CONCLUSION

SVC is not a usable substitute for FVC for elderly patients with cognitive impairment but is of some utility for those who tend to cough. An MMSE < 24/30 is predictive of inability to perform FVC and SVC.

The effects of multiple low doses of organophosphates on target enzymes in brain and diaphragm in the mouse

1. Multiple low doses of the direct acting organophosphates, ecothiopate, paraoxon and mipafox produced persistent and additive inhibition of diaphragm acetylcholinesterase. Paraoxon and mipafox had similar effects on brain acetylcholinesterase. There was greater recovery from inhibition between doses for paraoxon and ecothiopate than for mipafox. 2. Ecothiopate did not inhibit brain acetylcholinesterase but there was a small increase in activity. 3. Mipafox also had a cumulative inhibitory effect on brain neuropathy target esterase. 4. These results have particular implication for the use of multiple low doses of organophosphates occupationally by man.

Long-term oral etoposide in metastatic breast cancer: clinical and pharmacokinetic results

To evaluate the activity of long-term, single-agent oral etoposide against advanced breast cancer, this study employed etoposide 50 mg/day and 100 mg/day (given over 14 days) in previously treated and chemotherapy-naive patients with histologically confirmed, recurrent or metastatic breast cancer. Of 38 patients, 24 had had chemotherapy, 34 had prior radiotherapy, and 31 had received hormone therapy. Etoposide courses in both treatment groups were repeated every 4 weeks for at least two courses; delays were instituted when patients' total leukocyte nadir fell to or below 3.0 x 10(9)/l. Dose reductions were made in the 100-mg group (to 50 mg/day) if World Health Organization leukopenia grade 3 or higher was present. Plasma pharmacokinetic profiles were measured in selected patients to assess inter- and intrapatient variability in etoposide's oral bioavailability. No complete responses were achieved among the 36 patients evaluable for response, but eight patients had a partial response. Responses were more frequent at the 100-mg dose and in previously untreated patients (seven of eight partial responders had not had previous chemotherapy). Median duration of response was 16 weeks (range, 7 to 46). Myelosuppression (variable and unpredictable) and alopecia (universal) were the notable toxicities. Pharmacokinetic analyses of oral bioavailability revealed significant interpatient variability, but much less intrapatient variability when successive etoposide courses in individual patients were evaluated. Despite the relatively small number of patients in this study, the responses achieved by previously untreated patients suggest etoposide's value against breast cancer. Further trials should use pharmacokinetic studies to assess bioavailability as well as to help define 'target' etoposide doses, based on plasma etoposide levels, during treatment.

The effects of L-dopa on the activity of methionine adenosyltransferase: relevance to L-dopa therapy and tolerance

L-dopa, the major treatment for Parkinson's disease (PD), depletes S-adenosyl-L-methionine (SAM). Since SAM causes PD-like symptoms in rodents, the decreased efficacy of chronic L-dopa administered to PD patients may result from a rebound increase in SAM via methionine adenosyl transferase (MAT), which produces SAM from methionine and ATP. This was tested by administering intraperitoneally saline, or L-dopa to mice and assaying for brain MAT activity. As compared to controls, L-dopa (100 mg/kg) treatments of 1 and 2 times per day for 4 days did not significantly increase MAT activity. However, treatments of 3 times per day for 4 and 8 days did significantly increase the activity of MAT by 21.38% and 28.37%, respectively. These results show that short interval, chronic L-dopa treatments significantly increases MAT activity, which increases the production of SAM. SAM may physiologically antagonize the effects of L-dopa and biochemically decrease the concentrations of L-dopa and dopamine. Thus, an increase in MAT may be related to the decreased efficacy of chronic L-dopa therapy in PD.

Transendoscopic contact neodymium:yttrium aluminum garnet laser excision of tracheal lesions in two horses

Two male racehorses (1 Standardbred, 1 Thoroughbred) were examined because of intraluminal cervical tracheal lesions, located 60 to 70 cm from the nares. A contact neodymium:yttrium aluminum garnet laser with a chisel probe attached to the fiber end was used to transendoscopically debride a nonhealing tracheal ulcer and to excise a pyogranulomatous mass. In both horses, the surgical sites healed quickly and the lesions did not redevelop.

Ileal diverticulum as a cause of chronic colic in a horse

A 4-year-old Thoroughbred gelding with a history of chronic colic was referred for evaluation of signs of abdominal pain. Exploratory laparotomy revealed a diverticulum of the distal portion of the ileum located between the layers of the mesentery. The diverticulum was similar in location and appearance to acquired ileal diverticula described in human beings. Complete bypass of the diverticulum by ileocecostomy resulted in apparent resolution of the chronic colic in this horse.

Use of gastrotomy to relieve esophageal obstruction in a horse

Esophageal obstruction of 1 week's duration in a gelding was diagnosed by contrast radiography and esophagoscopy. A food bolus was found at the junction of the caudal thoracic portion of the esophagus and the cardia. A gastrotomy was performed through a cranial abdominal incision and a phytobezoar was manually broken down and removed. The gelding was started on complete pellet food and water on the fifth day after surgery. The horse remained clinically normal more than 1 year after surgery.

Studies on the sense organs on the palps of selected culicine mosquitoes

Four structures are found on the maxillary palps of female culicine mosquitoes: microtrichia, scales, sensilla chaetica, and thin-walled, bulb-shaped organs. The bulb organs are localized on the distal half of the ventral part of palpal segment 4, have perforated walls, are carbon dioxide receptors (Kellogg, in press), and vary in number among the species from 29/palp on Aedes aegypti to 89/palp on Culex restuans. An explanation for observed behavioral responses to carbon dioxide is given.