Novel approach for efficient resonance tracking in photoacoustic gas sensor systems based on a light-induced wall signal

Photoacoustic gas sensing is a method suited for the detection of radiation absorbing molecular species in the gas phase. Due to the backgroand-free detection, it has considerable benefits in the measurement of very low concentrations down to the parts-per-trillion range. Yet in resonant systems, the resonance frequency depends on several parameters like temperature or gas composition and therefore must be continuously determined. In the present work, we propose a new method of tracking the resonance frequency using a photoacoustic signal generated at the walls of the resonant cell. The method has been evaluated with two different photoacoustic setups intended for the detection of NO₂. We further propose an algorithm for finding the resonance frequency and evaluated the performance thereof. With this method, it is possible to detect the resonance frequency of a cylindrical and a dumbbell-shaped cell in less than two seconds and with an accuracy < 0.06% and < 0.2%, respectively.

Longitudinal rate of change in depression symptoms from pre- to post-COVID-19 onset among US mothers

Background

The extent of the psychological impact of the pandemic is still unfolding. Despite existing literature, most studies lack rigor. We assessed the longitudinal rate of intra-individual change in maternal depression symptoms from before to after COVID-19 onset among US mothers enrolled in a home visiting program with robust adjustment for family contextual factors. We hypothesize that the rate of change in maternal depression symptoms increased after the pandemic onset.

Methods

Eligibility included mothers with ≥1 depression assessment both prior to and after March 16, 2020; thresholds of ≥ 13 on the Edinburgh Postnatal Depression Scale and ≥10 on the Patient Health Questionnaire-9 identified probable depression. We used a generalized linear mixed effects longitudinal model with a random intercept and random slope for time (years) to analyze probable depression (event=‘Yes') pre- and post-COVID. Covariates for model estimation were based on the literature and theory.

Results

Our cohort of 3,431 mothers included 43% non-Hispanic White, 21% non-Hispanic Black, and 31% Hispanic races/ethnicities; 58% from rural/small towns, 18% Spanish-speaking, 63% with one child, median age of 29 and median 2 years follow-up. Households included: 82% low income, 24% low education, 10% insecure housing, 29% single parents, 21% mental illness, 10% substance abuse, and 8% domestic violence. Fourteen percent screened positive for depression pre-COVID, and 10% post-COVID. Depression was significantly higher pre- versus post-COVID, with no significant difference in the rate of change over time. Significant variables (p &lt; 0.05) associated with depression included race/ethnicity, region of the country, number of home visits, mental illness, substance abuse, and domestic violence.

Conclusions

After controlling for family contextual factors, we did not find a significant increase in maternal depression post-COVID-19. Additional research is needed to examine subgroups and the timing of events.

Key messages

• The extent of the psychological impact from the pandemic is still unfolding.

• It is difficult to fully articulate its effects without rigorous, longitudinal research designs.

Expert opinion on NSCLC small specimen biomarker testing - Part 1: Tissue collection and management

Biomarker testing is crucial for treatment selection in advanced non-small cell lung cancer (NSCLC). However, the quantity of available tissue often presents a key constraint for patients with advanced disease, where minimally invasive tissue biopsy typically returns small samples. In Part 1 of this two-part series, we summarise evidence-based recommendations relating to small sample processing for patients with NSCLC. Generally, tissue biopsy techniques that deliver the greatest quantity and quality of tissue with the least risk to the patient should be selected. Rapid on-site evaluation can help to ensure sufficient sample quality and quantity. Sample processing should be managed according to biomarker testing requirements, because tissue fixation methodology influences downstream nucleic acid, protein and morphological analyses. Accordingly, 10% neutral buffered formalin is recommended as an appropriate fixative, and the duration of fixation is recommended not to exceed 24–48 h. Tissue sparing techniques, including the ‘one biopsy per block’ approach and small sample cutting protocols, can help preserve tissue. Cytological material (formalin-fixed paraffin-embedded [FFPE] cytology blocks and non-FFPE samples such as smears and touch preparations) can be an excellent source of nucleic acid, providing either primary or supplementary patient material to complete morphological and molecular diagnoses. Considerations on biomarker testing, reporting and quality assessment are discussed in Part 2.

Pancreatic fistulas following distal pancreatectomy are unrelated to the texture quality of the pancreas

PURPOSE

The relevance of pancreatic texture for pancreatic fistula (POPF) formation after distal pancreatectomy (DP) remains ill defined. Recent POPF definition adjustments and common subjective pancreatic texture assessment are further drawbacks in the investigation of pancreatic texture as a factor for POPF development after DP.

METHODS

The predictive value of pancreatic texture by histologic assessment was investigated for POPF formation after DP, respecting the updated 2016 fistula definition. Histologic evaluation at the resection margin included amount of steatosis, degree of fibrosis, and pancreatic duct size.

RESULTS

A total of 102 patients who underwent DP were included. Thirty-six patients developed POPF. There was no difference in histologic variables in patients with and without POPF. In the univariate analysis, none of the three histologic features showed significant correlation with POPF formation. The ROC (receiver operating characteristic) curve demonstrated poor utility for the grade of steatosis 0.481 ± 0.058 (p = 0.75) and grade of fibrosis 0.466 ± 0.058 (p = 0.57) as predictive factors for POPF formation.

CONCLUSION

Results indicate that pancreatic texture does not predict POPF formation following DP. This is particularly relevant in the context of the increasing use of robotic and laparoscopic approaches for DPs with limited clinical pancreatic texture assessment by palpation.

Social determinants of health, adverse childhood experiences, and maternal-infant relationship

Background

Low strength of maternal-infant relationship (MIR) is consistently associated with early childhood obesity risk. Because obesity often persists once it develops, primary prevention is needed early. Home visiting programs support families with social determinants of health (SDH) and adverse childhood experiences (ACEs); SDH and ACEs contribute to health inequities. Addressing SDH and ACEs may facilitate improvements in MIR and ultimately mitigate early childhood obesity risk. Limited to no research has examined the association between ACEs, SDH, and MIR. In the context of a national, evidence-based home visiting program, we asked: are SDH and ACEs associated with low MIR?

Methods

This sample includes 6,972 children ages 0–&lt;24 months enrolled in the Parents as Teachers home visiting program across the United States from sites using the Life Skills Progression (LSP) instrument through February 2020. Low MIR is dichotomized from a 1-5 scale, with low scores reflecting low nurturing, bonding, and responsiveness. We used the literature, theory, and a stepwise logistic regression model-building process to identify a parsimonious model for MIR.

Results

Preliminary results reflect 34.2% Hispanic or Latino, 22.7% non-Hispanic Black, 35.3% non-Hispanic Other race; 83.9% low income; 36.9% low education; and 13.4% mothers scoring low for MIR. Notable findings from modeling include: physical ACEs, captured here as child abuse or neglect (OR: 5.01, 95% CI: 4.10-6.11); mental illness ACEs, captured here as a mother/parent with mental illness (OR: 1.31, 95% CI: 1.05-1.63), or the mother/parent treated violently (OR: 1.95, 95% CI: 1.56-2.40). Protective associations include mothers' support of child development and self-esteem scores.

Conclusions

Understanding the complex interplay of SDH, ACEs, and MIR is critical for developing interventions that address “upstream” family characteristics in order to mitigate early childhood obesity risk. ACEs play a predominant role.

Key messages

This is the first known study to concurrently examine maternal-infant relationship, social determinants of health, and adverse childhood experiences. Home visiting programs may be critical partners in addressing these needs given their reach.

A novel NGS library preparation method to characterize native termini of fragmented DNA

Biological and chemical DNA fragmentation generates DNA molecules with a variety of termini, including blunt ends and single-stranded overhangs. We have developed a Next Generation Sequencing (NGS) assay, XACTLY, to interrogate the termini of fragmented DNA, information traditionally lost in standard NGS library preparation methods. Here we describe the XACTLY method, showcase its sensitivity and specificity, and demonstrate its utility in in vitro experiments. The XACTLY assay is able to report relative abundances of all lengths and types (5′ and 3′) of single-stranded overhangs, if present, on each DNA fragment with an overall accuracy between 80–90%. In addition, XACTLY retains the sequence of each native DNA molecule after fragmentation and can capture the genomic landscape of cleavage events at single nucleotide resolution. The XACTLY assay can be applied as a novel research and discovery tool for fragmentation analyses and in cell-free DNA.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

A ligation-based single-stranded library preparation method to analyze cell-free DNA and synthetic oligos

Background

Cell-free DNA (cfDNA), present in circulating blood plasma, contains information about prenatal health, organ transplant reception, and cancer presence and progression. Originally developed for the genomic analysis of highly degraded ancient DNA, single-stranded DNA (ssDNA) library preparation methods are gaining popularity in the field of cfDNA analysis due to their efficiency and ability to convert short, fragmented DNA into sequencing libraries without altering DNA ends. However, current ssDNA methods are costly and time-consuming.

Results

Here we present an efficient ligation-based single-stranded library preparation method that is engineered to produce complex libraries in under 2.5 h from as little as 1 nanogram of input DNA without alteration to the native ends of template molecules. Our method, called Single Reaction Single-stranded LibrarY or SRSLY, ligates uniquely designed Next-Generation Sequencing (NGS) adapters in a one-step combined phosphorylation/ligation reaction that foregoes end-polishing. Using synthetic DNA oligos and cfDNA, we demonstrate the efficiency and utility of this approach and compare with existing double-stranded and single-stranded approaches for library generation. Finally, we demonstrate that cfDNA NGS data generated from SRSLY can be used to analyze DNA fragmentation patterns to deduce nucleosome positioning and transcription factor binding.

Conclusions

SRSLY is a versatile tool for converting short and fragmented DNA molecules, like cfDNA fragments, into sequencing libraries while retaining native lengths and ends.

Ancient DNA Resolves the History of Tetragnatha (Araneae, Tetragnathidae) Spiders on Rapa Nui

Rapa Nui is one of the most remote islands in the world. As a young island, its biota is a consequence of both natural dispersals over the last ~1 million years and recent human introductions. It therefore provides an opportunity to study a unique community assemblage. Here, we extract DNA from museum-preserved and newly field-collected spiders from the genus Tetragnatha to explore their history on Rapa Nui. Using an optimized protocol to recover ancient DNA from museum-preserved spiders, we sequence and assemble partial mitochondrial genomes from nine Tetragnatha species, two of which were found on Rapa Nui, and estimate the evolutionary relationships between these and other Tetragnatha species. Our phylogeny shows that the two Rapa Nui species are not closely related. One, the possibly extinct, T. paschae, is nested within a circumtropical species complex (T. nitens), and the other (Tetragnatha sp. Rapa Nui) appears to be a recent human introduction. Our results highlight the power of ancient DNA approaches in identifying cryptic and rare species, which can contribute to our understanding of the global distribution of biodiversity in all taxonomic lineages.

Spleen preserving management of a non-parasitic splenic cyst in pregnancy

Non-parasitic splenic cysts are rare entities. In pregnancy, they are rarer still, with as few as seven cases reported in the literature. There is little consensus regarding the optimal management of this condition in pregnancy. Although small, the theoretical risk of intrapartum splenic rupture is associated with a fetal mortality rate as high as 70%. The authors of at least three case reports advocate total splenectomy as first-line management of splenic cyst in pregnancy. Paradoxically, spleen conserving surgery is the recognised gold standard treatment for symptomatic splenic cysts in non-pregnant patients. We present a case of a large maternal splenic cyst that was treated successfully with a laparoscopic cystectomy.

Evaluation of graft-host response for various tissue sources and animal models

The efficacy of pancreatic islet transplants in correcting hyperglycemia and slowing the progression of complications in diabetics has been confirmed by many experimental and clinical studies. Unfortunately, the availability of human islets is extremely limited and, therefore, treatment of large numbers of human diabetic patients will almost certainly require either the use of islets harvested from animals (xenografts) or the use of insulin-secreting genetically modified cells of either human or animal origin. There is currently no effective regimen which will allow long-term survival of xenogeneic islets from widely unrelated donor-recipient combinations, such as pig-to-rodent, pig-to-dog, or pig-to-primate. There is considerable interest in the development of immunoisolation techniques for protection of donor islets. However, most materials used in immunoisolation devices are relatively bio-incompatible. Poly-L-lysine-alginate microcapsules are biocompatible and provide an optimal geometry for transmembrane diffusion of insulin and nutrients. Microcapsules allow long-term survival of xenogeneic islets in diabetic rodents or dogs with induced diabetes. However, mice and rats with spontaneous diabetes destroy encapsulated islet grafts within 2 to 3 weeks. Biopsies reveal large numbers of macrophages, immunoglobulins and limited numbers of helper and cytotoxic T-cells in the peri-microcapsule environment of the peritoneal cavity. Cytokines have been identified in peritoneal fluid from mice with islet grafts and may play a role in encapsulated islet destruction. Targeted immunomodulation by treatment of recipients with either anti-helper T-cell antibodies, or fusion proteins which block costimulatory interactions between antigen presenting cells and host T-cells have demonstrated synergy in significant prolongation of encapsulated islet xenograft survival in NOD mice with spontaneous diabetes. Technical improvements in microcapsule design also have contributed to prolonged graft survival. "Double-wall" microencapsulation provides a more durable microcapsule and islet pretreatment prior to encapsulation reduces the frequency of defective capsules with islets entrapped in the membrane. Long-term durability of encapsulated islet grafts remains a concern and further improvements in microcapsule design are a prerequisite to clinical trials.

Systemic heparin in the early management of ruptured intracranial aneurysms: review of 104 consecutive cases and comparison with concurrent controls

The records of 104 patients treated prophylactically with heparin during gradual carotid ligation after rupture of an intracranial aneurysm, 11 patients, who received heparin after the development of an ischemic neurological deficit during clamp closure, and 46 patients who did not receive heparin during clamp closure were reviewed. The incidence of ischemic neurological deficit, both permanent and transient, was 19.2% in the prophylactic heparin group compared with 38.6% in the control group. The incidence of recurrent intracranial hemorrhage was 9.6% in the heparin group vs. 26.1% in the control group. All differences were statistically significant at or below P less than 0.01 by the Mantel-Haenszel statistical test. Possible mechanisms for the reduction in morbidity and mortality in patients receiving heparin are discussed.

Rearrangement and transcription of a T-cell receptor beta-chain gene in different T-cell subsets

The functionally defined sets of T lymphocytes--helper T cells, cytotoxic T cells, and suppressor T cells--were examined for the possible involvement of a recently identified T-cell receptor beta gene locus in receptor formation. Since gene rearrangements are required for functional gene expression, cloned T-cell lines from each of the groups were surveyed for the expression of unique gene rearrangements. In addition, cell lines that showed gene rearrangements were further tested for the expression of the mature 1.2- to 1.3-kilobase mRNA transcribed from a productive gene rearrangement. The results of such experiments show that helper and cytotoxic T cells may use a common beta chain of the receptor, whereas suppressor cells do so rarely, if at all.

Radiation sensitivity of 9L gliosarcoma cells at different oxygen pressures

Monolayer cultures of 9L gliosarcoma cells received radiation doses of 0-1750 ret at oxygen pressures ranging from 50 to 545 mmHg. Growth inhibition, which could be demonstrated in all radiated cell cultures, was most pronounced in those receiving the highest dose of radiation. There was no relationship between the radiation sensitivity of the cells and the oxygen pressure of the fluid media of the cell cultures at the time radiation was administered. Cells subjected to the lowest oxygen tensions (50-52 mmHg) did not grow whether they had received radiation or not. The technical difficulty of removing oxygen from tissue culture media is described. Possible points of significance in the findings of this study are discussed with regard to previous observations on the radiosensitivity of the 9L tumor model, current concepts in radiobiology, and implications for future studies of human tumors in cell culture.

Insulin-specific antibodies and insulitis in mice immunized with purified porcine insulin

The murine antibody response to porcine insulin is controlled by immune response genes of the major histocompatibility complex. Animals of the one haplotype (H-2d) produce specific antibodies to pork insulin, while animals of other haplotypes do not. We analysed the antibody responses to purified pork insulin by animals of responder and non-responder haplotypes, and attempted to correlate these responses with histopathological findings at necropsy. Animals of responder and non-responder haplotypes immunized with insulin or control preparations generally presented similar pathological pictures. We found granulomatous inflammatory infiltrates in the liver and the periphery of the pancreas, mononuclear interstitial pancreatic infiltrates, and mononuclear hepatic pericholangitis. Those were ascribe to adjuvant. One animal (H-2d) immunized with insulin showed focal peri-insulitis. Otherwise, the inflammatory infiltrates in the islets reported by others were not observed. The significance of insulitis in experimental insulin immunity is discussed.

Evaluation of megadose vitamin therapy in an experimental brain tumor

A mixture of vitamins C and B12 in high dosage, which has been reported to eradicate ascites tumors in rats, was tested for its antineoplastic effect against the L9 glioma in Fisher CDF strain rats. No difference in survival time between animals receiving the vitamin mixture and controls could be demonstrated. Possible reasons for the different response to therapy in the two experimental tumor systems are discussed.

[Biochemical and immunological characterization of a suppressor factor specific for the terpolymer GAT]

It has been possible to extract a suppressor factor specific for antigen from non-responder animals that have developed suppressor cells. This factor shows a high affinity for the antigen and cross-reacts with related antigens. It does not carry antigenic determinants of the constant region of immunoglobulin molecules but carries Ia determinants and has an affinity for the GAT comparable to the affinity of the anti-GAT antibodies.

The effect of isordil and cyclospasmol on vascular spasm induced in the basilar artery of the cat

Vasospasm of the basilar artery of the cat was induced by subarachnoid bleeding and was observed by a transoral approach to the vessel. Intravenous Isordil (2 to 4 mg/kg) given following vasospasm produced vasodilatation with minimal arterial hypotension. Cyclospasmol, administered intravenously after vasospasm or orally prior to vasospasm, was ineffective in relieving or preventing basilar artery spasm.

A combined technique for treating certain aneurysms of the anterior communicating artery

✓ Thirty-one patients with aneurysms of the anterior communicating artery that filled from both sides during carotid arteriography were treated by a combined operative procedure consisting of clip-ligation of one proximal anterior cerebral artery followed by gradual occlusion of the opposite common carotid artery with a Crutchfield clamp. In 14 patients, intravascular pressure recordings in the carotid vessels in the neck were obtained both before and immediately after ligation of the anterior cerebral artery. Before ligation the average intravascular pressure reduction was 55%, while after ligation the average reduction was 71%. Of the 31 patients, 22 have had good results and no recurrent hemorrhage. Nine patients died, four from recurrent hemorrhage. Follow-up carotid arteriography in nine patients showed the aneurysm obliterated in six, smaller in one, and unchanged in two. The results of this study indicate that treatment of certain anterior communicating aneurysms by the combined operative approach described is useful.