One month later, seeing toddlers with oddly red hair, cracked skin, and swollen limbs no longer shocks me. Nor am I shocked that some of them never return home.It’s Summer 1972. I’ve just finished college and I’m spending the summer in Haiti. When I finally reach l’Hôpital le Bon Samaritain after an 8-hour journey in a rickety Malnutrition, an age-old killer and accomplice in the deaths of impoverished children, is my first introduction to tropical medicine.Seven years later, I attend the London School of Tropical Medicine and Hygiene and take a deeper dive into malnutrition’s history, physiology, and perilous synergy with infectious diseases. Nonetheless, my fellow students and I are still “looking through a glass darkly.”Then come science and strategies that fuel hope. When experts in the 1980s and 1990s champion micronutrients plus diverse, balanced diets; WHO’s initial package of Expanded Programme on Immunization vaccines; and oral rehydration for childhood diarrhea, child survival rises. Over time, re-feeding regimens meant to rescue children from death are replaced by ready-to-use therapeutic foods, which often forestall it.The Lancet, global food insecurity had continued to grow and worsen malnutrition. So is the glass half empty or half full? And how should a public-facing author weigh discouraging facts against the past three decades’ otherwise quiet-but-steady progress?Today, global experts also parse proximate causes of malnutrition from colonialism to climate to monoculture, as well as lifelong consequences such as stunting.Within Our Grasp—Childhood Malnutrition Worldwide and the Revolution to End It, Sharman Apt Russell weaves modern nutritional science with interviews and blueprints for hope. Looking back, what especially inspires hope are stories of people determined to fight malnutrition, like those who developed the nutrient-rich paste Plumpy’Nut . Does Russell’s book also carry a whiff of cultural tourism? Yes. But, to me, this was far outweighed by the book’s sincere and illuminating conversations with newly empowered farmers, organizers, and teachers  during the author’s 2016 field trip to Malawi.In Library Journal describes Within Our Grasp, and that’s just one of many glowing blurbs on Amazon. A professor emeritus in humanities at Western New Mexico University and associate faculty at Antioch University, Russell previously authored Diary of a Citizen Scientist , Knocking on Heaven’s Door (winner of the Arizona/New Mexico Book Award), Teresa of the New World (winner of the Arizona Authors Association Award), and (with funding from the Rockefeller Foundation) Hunger: An Unnatural History.“Russell’s passion for citizen science and her jargon-free presentation of information relating to malnutrition will open worlds for most readers, from high school students to sociologists” is how Within Our Grasp is an excellent book to recommend to undergrads majoring in global development, students of medicine and public health, and post-graduate trainees embarking on overseas rotations in low- and middle-income countries. Or anyone else, for that matter, who wants to explore modern solutions to the age-old problems of hunger and survival of the weakest.In short, Within Our Grasp, I turned to three American Society of Tropical Medicine and Hygiene colleagues for further perspective. For 35 years, Dr. Terrie Taylor has done malaria research in Malawi, where Russell did her grassroots reporting. Dr. Natasha Hochberg currently studies the nexus of undernutrition and tuberculosis in India. Dr. David Hamer’s work is largely focused on implementation research designed to advance maternal, newborn, and child health in real-life settings in low- and middle-income countries.After finishing My earliest research project in Africa involved onchocerciasis in Sudan. I was mainly based in Khartoum, but the field sites were up north in a place called Abu Hamad and in southern Sudan (not yet a country) in a town called Wau. As far as I could tell, those folks were not suffering from malnutrition. I wouldn’t say it was a time of plenty—they had fairly monotonous diets—but there was plenty of food.Then I went to Malawi in July 1986, and it was a much more appealing place to work. There were roads! There was electricity! You could imagine functioning there. Of course, it was also the best time of year to be there. The harvest had just finished, so everybody had food. I was still hoping to study onchocerciasis, but when I met the only pediatrician at Queen’s Hospital in Blantyre, she thought I should I focus on malaria, which was the single highest cause of admissions to the hospital for kids and the highest cause of death. So, I began my work on malaria.But once the medical school opened in 1991, there was “handover,” or morning report. So I would go to the morning report and listen to this litany of how many kids were admitted yesterday, which wards they went to, and how many died.Malnutrition had, far and away, the highest mortality rate: 30%, 40%, compared with 10% in other sections of Pediatrics. The malnutrition wards were overflowing with marasmic and kwash kids. Overflowing.Yes, it was the early nineties, and it was grim. As Sharman Apt Russell describes in her book, there were people trying many different approaches to malnutrition without really understanding it. But slowly there were breakthroughs in management.I remember when Mark Manary came to Malawi as a proponent of Project Peanut Butter. He was a quiet, serious person who did a ton of work and built this factory, but you had to pry the story out of him. He was never showy; it was never about him.He had just started to encourage community-based management of malnutrition as opposed to hospital-based care. It was much more sustainable, much more cost-effective.I double-checked with the head of Pediatrics. Now, the kids who come into the hospital for malnutrition are those with co-morbidities, like cerebral palsy, or very bad birth injuries. The hospital doesn’t see “regular” malnutrition any more.I also asked about possible bias because I have always worked in the central hospital in a big city as opposed to a rural setting, but he said the improvement in nutritional status was evident at all levels of the health-care system. Then I discovered a very nice survey that covered 10,000 kids in 10 districts—rural and urban. Rates of child malnutrition are now at an all-time low of 5%. There was a little blip with COVID and the food insecurity associated with it, but the overall situation is so much better. The messages about balanced diets are getting through, and Chiponde is available for free through the Ministry of Health. That’s something else I wanted to emphasize. Malawi has been unusual on the continent in hewing to free health for all.It’s true there are two parallel health systems—private and public—but the public system works. The Chiponde gets out to the health centers, and kids who need it come and pick it up on a regular basis and take it home. It’s also logged in. People keep track of it.Although it had been building since the bad rains of the previous year, it hit very quickly. The cassava failed, and then the maize stocks were sold from Malawi. So it was a juxtaposition of adverse weather and bad political decisions followed by no communication. Then, all of a sudden, we realized, “Oh my God. There’s no food.” Malawi had already fallen from grace with the Danes and the Brits, so it wasn’t easy to generate external support.I was there just six months, and the malaria season was rough, but the famine lasted until the crops came in. At that point, things began to improve, and there was also a change in government. Against international advice, the next president invested in fertilizers. Within two or three years, maybe by 2005 or 2006, Malawi was exporting maize.With respect to climate, people are starting to notice that everything is exaggerated. The cold season is colder. The rainy season is wetter. But beyond that . . . it’s kind of like what’s been happening in the U.S. “Oh, this is the 10th hundred-year storm.” So awareness of climate change is just beginning to dawn.In terms of agriculture and technology, Africa is definitely embracing more technology that enhances productivity . . . in fact, the benefits of that technology probably outweigh the negative impacts of weather. Right now, for example, there’s not a lot of pesticide use, but the land is being flogged with fertilizer.What impressed me most were the stories of the community-based workers who hung in there through thick and thin. And the well-observed details. It also made me go back in time and think. I’ve seen three and a half decades of attempts to use a variety of community-based approaches in Malawi. People just kept at it. This is how long it takes to see results. We’ve seen it with malaria, we’ve seen it with maternal mortality rates, and we’ve seen it with malnutrition.Why put so much emphasis on understanding the intersection of HIV and TB, or diabetes and TB, or evaluating new diagnostics, while paying so little attention to the role of undernutrition? From a research perspective, there are so many questions to answer. And from a public health perspective, there’s so much we need to do.Yes, while working internationally in places like Peru, Honduras, Bangladesh, Niger, and Togo, the intersection of poverty and infectious diseases was always apparent to me. But my research focusing on undernutrition and TB [tuberculosis] began roughly 10 years ago at a meeting in India where TB researchers were talking about designing novel diagnostic tests and improving adherence to treatment, and a leader in the field made a powerful statement. In effect, Anurag Bhargava said, “You’re missing the picture. Malnutrition is really the leading driver of TB worldwide.” His talk had a profound effect on me as I thought, First of all, with 10 million cases and 1.5 million deaths in 2020, TB remains the leading infectious killer worldwide after COVID-19. But what we now know is that a quarter of TB cases worldwide, and, in some parts of the world, more than 50% of cases are attributable to malnutrition. That in itself is striking, but there are actually many ways in which malnutrition and TB intersect. Malnutrition not only increases the risk of developing active TB disease, but also drives poor outcomes. Malnourished people more often fail therapy, which increases onward transmission and places them at a heightened risk for drug-resistant infections. Finally, they more often develop severe disease, and they’re more likely to die of TB.Clinical Infectious Diseases.We now have data from our Indian cohorts that correlate malnutrition and mycobacterial burden and patients’ radiographic extent of disease. In one of our studies, TB patients with severe malnutrition had, on average, 11% more lung affected compared with those with a normal body mass index, and they also had an almost 5-fold increased odds of pulmonary cavitation. This reinforces the idea that malnutrition affects the pathogenesis of disease. Malnutrition also affects the pharmacokinetics and absorption of TB drugs. This has been demonstrated by data from our colleagues showing low levels of rifampicin and isoniazid in malnourished children. So now we’re starting to move to population-level work. What can be done about this? Our research group recently completed modeling work which suggests that nutritional interventions could be a cost-effective way to prevent TB disease in India; this paper has now been published in One example is the Papworth Village Settlement in England in the pre-antibiotic era of the early 1900s, where TB patients received food, housing, employment, and medical supervision. Anurag Bhargava and his team went back and analyzed its data to compare the rates of disease among family members of Papworth residents with rates among contacts of TB patients in surrounding areas. Although the Papworth interventions did not reduce TB transmission (children still became infected), they markedly reduced progression to TB disease. Other data come from a World War II prisoners of war camp in Germany, where they looked at rates of TB disease among different groups of soldiers, some of whom received a 1,000 calorie-per-day Red Cross supplement in addition to the standard camp diet. Those who did not receive the additional protein and calories had much higher rates of TB disease.Unfortunately not yet, partly because diagnosing TB in children is tricky. It’s not impossible, but it requires a whole different algorithm. That’s why our current work is primarily focused on adults. At the same time, my hope is eventually to move into the world of kids, not only because malnutrition increases their risk for many respiratory infections, but because they’re also at higher risk than adults for progressing to active TB following exposure. My ultimate goal is to encourage public health programs to build inter-sectoral collaborations and integrate nutrition in the fight against TB and other infectious diseases.On my first day as an undergraduate at Amherst, I met a friend who later repeatedly said, “You need to go to Bangladesh. My country needs people to work in it.” And so I eventually went to Dhaka during medical school and did research at the Institute for Food Science and Nutrition. I also spent time at the International Centre for Diarrhoeal Disease Research  and rotated through a clinical unit where I was floored to see so many children with marasmus and kwashiorkor, and eyes completely destroyed by a lack of vitamin A. I also saw a variety of infections superimposed on wasting and stunting. That’s what triggered my interest.In 2011, I went to Zambia because I had just received a ten-million-dollar grant from the Gates Foundation for a community-based intervention using chlorhexidine for newborn cord care. But being in Zambia was like being in a public health grocery store. There were just so many things to pull off the shelf and work on. Among other things, I had the opportunity to evaluate the impact of a nationwide program of rural sanitation and hygiene on wasting and stunting.Yes. In 2019, wasting, which is the leading risk factor for child pneumonia deaths, contributed to 55% of deaths. In addition, 90% of wasting-related child pneumonia deaths occurred in 40 low- and middle-income countries, the majority in Africa. So even though wasting accounts for a relatively small proportion of undernutrition compared with underweight or stunting, when it’s present, it’s a major risk factor both for acquiring infection and for more severe cases of pneumonia and diarrhea. In malaria, the data are more complicated, but wasting probably increases its severity as well. So we really need to address wasting to reduce both the burden and mortality of infectious diseases in younger children.Stunting, on the other hand, is a different problem because it’s so widespread and multifactorial. Some of it may start in the antenatal period, or even pre-conception. When that happens, children are small for gestational age at birth. But most stunting results from what happens to a child during their first year or two of life. This includes inadequate nutrition and dietary protein, and probably micronutrients like zinc that are important for growth. In addition, inadequate hygiene, poor sanitation, and contaminated water leading to food- and waterborne infections and diarrhea, all contribute to stunting.kapenta, because protein-calorie malnutrition is a major factor in stunting. We also encouraged adding locally available fruits and vegetables that mothers might not otherwise use.For several years now, we’ve been looking at one particular strategy in Zambia. In fact, we just completed our data collection in rural areas of Eastern and Southern Province. Although I sometimes call it a pilot study, we actually started with a small, randomized controlled trial of community-based mothers’ groups  where we enrolled mothers with children who were six months or younger. We picked one mother to be the leader and gave her a curriculum. Every two weeks, the mothers met and received education in a fun, interactive way that included games, challenges, and practical teaching about age-appropriate nutrition. That meant we emphasized breastfeeding during the first six months of life; then safe complementary foods; then dietary diversity using low-cost, locally-available sources of proteins such as ground nuts (peanuts) or, in Zambia, little baby fish called Our goal over time was to improve nutritional status, growth, and cognitive development. Our 2014–2016 study of 500 children in southern Zambia accomplished all three goals. So, for the last two and a half years, we’ve been doing the same thing on a larger scale with 5,000 mother–baby pairs along with a detailed evaluation of a subset, because we don’t need the full 5,000 for adequate power. It will be interesting to see if our latest data replicate our previous results, because the more recent program was integrated into public health plus community-based organizations.The funding came primarily from USAID Zambia, but also Grand Challenges Canada, which had a program called Saving Brains. That just ended, but USAID subsequently funded an offshoot emphasizing child development. Fortunately, my team includes two people with this expertise. A book of Zambian folk stories has now been translated into multiple Bantu languages to evaluate our program’s impact on older children from some of our households with respect to their ability to read.American Journal of Tropical Medicine and Hygiene. One of the leaders of ARISE is Wafaie Fawzi at the Harvard School of Public Health. During the early part of the pandemic, ARISE conducted a series of rural and urban surveys using cell phones. One high-level takeaway in 1,800 households was COVID-19’s negative effects on the price of food and dietary quality. Dietary diversity and prime diet quality scores also fell. This was partly due to higher prices, but also to decreased access to food.Although I wasn’t directly involved in the study, I served as an associate editor for a collection of papers done by ARISE, a network of collaborators in Ethiopia, Nigeria, and Burkina Faso, and published in 2021 in the For years, a lot of acute malnutrition was managed at the hospital level. But in recent years, there’s been a push to see if some management can be offloaded to the primary health center or the community. For moderate acute malnutrition, this is entirely feasible. For milder cases or variants of severe acute malnutrition, it’s also possible, but first you need screening procedures. Then you need referral systems so children can be adequately assessed to determine whether they can be safely managed at home as opposed to a health facility. You also need people trained to monitor the children and provide appropriate supplements.Basically, a lot of my work over the last 20 years has involved testing health interventions that are already backed by science. But we still need to figure out how to make them happen in real-world settings. Once that becomes clear, we can develop better guidelines and implementation strategies.


Experience and research show that screening for malnutrition in primary care mainly takes place by monitoring the weight parameter and that validated screening instruments are hardly used. In this study we examined the effectiveness and predictive value of weight evolution in screening for (risk of) malnutrition in older people living at home, in comparison with a validated screening tool, namely the Mini Nutritional Assessment Short Form (MNA-SF).This project was a prospective, longitudinal study with quantitative data that took place in the province of Antwerp (Belgium) from December 2020 until June 2021. The target group of this study consisted of people over 70 living at home who were visited by a home nurse on a regular basis (at least once a month). The outcome measure was the weight evolution over six months compared with the score on the MNA-SF at month six. Weight was measured and recorded once a month during 6 months. At the last weight measurement, the MNA-SF was administered. In order to assess their own nutritional state, three additional questions were asked after taking the MNA-SF.A total of 143 patients gave consent to participate, of which 89 were women and 54 men. The mean age was 83.7 years (SD6.62) with a range of 70 to 100 years. Based on the MNA-SF score measured after six months, 53.1% (76/143) of participants had a normal nutritional status, 37.8% (54/143) scored risk of malnutrition and 4.9% (7/ 143) was malnourished. In order to detect people with (risk of) malnutrition, a PPV of 78.6%, a NPV of 60.7%, a sensitivity of 19.3% and a specificity of 96.0% were established with a weight evolution of ≥ 5% weight loss at six months. To detect malnutrition, our results showed respectively 33.3%, 98.4%, 71.4% and 92.3%.In this study, weight evolution has a low sensitivity in screening for (risk of) malnutrition in people over 70 living at home compared to the MNA-SF. However, in order to detect people with malnutrition, this study demonstrated a sensitivity of 71.4% and a specificity of 92.3% for a weight loss of ≥ 5% at six months.The online version contains supplementary material available at 10.1186/s12875-023-02020-w. In a world where there is increasing attention for obesity and the associated health risks, it seems paradoxical to highlight malnutrition. However, malnutrition is a heavily underestimated and frequently occurring pathology . In 2013The negative consequences of malnutrition cannot be underestimated. Studies showed more frequent disease episodes, a slower recovery, a higher risk of falling, a longer hospital stay, more complications, a reduced quality of life and a shorter life expectancy in patients with malnutrition , 4. DeprScreening for malnutrition is indispensable but health care providers only recognize half of malnourished patients , 7. VariPractical experience and research show that screening in primary care mainly takes place by monitoring weight and that validated screening instruments are hardly used , 10, 11.This project was a prospective, longitudinal study with quantitative data. There was no control group. The outcome measure was the weight evolution over six months compared with the score on the MNA-SF at month six.From October to December 2020, home nurse groups in the province of Antwerp (Belgium) were selected by convenience and contacted by telephone to assess their interest in participating in the study. We asked the committed home nurse groups to introduce the study to their patients. The number of participating nurse groups was determined by convenience.The target group of this study consisted of community-dwelling people older than 70, living in the province of Antwerp (Belgium) and visited by a home nurse on a regular basis (at least once a month). Exclusion criteria that were used were: persons with an estimated life expectancy of less than six months and persons on artificial nutrition. The nurse estimated the life expectancy as determined by the ‘surprise question’ in the Palliative Care Indicator Tool (PICT). If the patients agreed to participate, the researcher and the nurse assessed the eligibility for inclusion.We provided the home nurses with the necessary information documents and consent forms per patient. We provided the nurses with the questionnaire, in which the MNA-SF and additional questions were described, and the accompanying manual. In patients who met the inclusion criteria and after the informed consent had been signed, we measured and recorded weight once a month during 6 months, in the morning and without clothing. At the last weight measurement, we administered the MNA-SF and classified patients into three categories: normal nutritional status (MNA-SF score of 12–14), risk of malnutrition (score of 8–11) or malnutrition (score of 0–7) . We refeIn order to assess own nutritional state, we asked three additional questions immediately after taking the MNA-SF, namely:“Do you think you eat well?”“Do you still enjoy eating moments?”“During the past six months, have there been any situations that caused a sudden weight change? And if so, what caused this?”Additional demographic data  were included in the questionnaire.To test weight evolution as a screening instrument against a validated screening tool, namely the MNA-SF, a sample size of 108 patients was calculated. This was based on the sample size necessary for diagnostic testing, with a significance level  of 0.05, a strength of 0.80 and a prevalence of (risk of) malnutrition of 36% .All collected data were stored in an Excel file. A descriptive population table was created based on these data. We categorized body mass index (BMI) according to the limit values for people over 65 of the Flemish Institute for Healthy Living . In thisWe determined the predictive value of weight evolution, compared to the MNA-SF, using evaluation of the sensitivity and specificity visualized in a Receiver Operating Characteristic (ROC) curve. We calculated the weight evolution by determining the percentage difference between the last and the first weight measurement. The positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity were calculated for different cut-off values of weight evolution. This was done for screening for the risk of malnutrition and malnutrition, and also separately for the screening for malnutrition.We performed the statistical analysis in statistical software program R, version 4.0.2.This study was performed in accordance with the Declaration of Helsinki. All participants must give their agreement via informed consent prior to the start of the study. The Ethics Committee of the KU Leuven University Hospitals granted permission for this study on October 15, 2020. (MP016365) All authors gave consent for publication. Participants were informed in advance about publication of the results and consented by signing the informed consent form.In the autumn of 2020, we contacted seven different groups of home nurses from the province of Antwerp, Belgium. Each group committed to this study and selected patients who met the inclusion criteria. In total, 143 patients gave their informed consent to participate, of which 89 were women and 54 men. The mean age was 83.7 years (SD 6.62) with a range of 70 to 100 years.  of participants had a normal nutritional status, 37.8% (54/143) was at risk of malnutrition and 4.9% (7/ 143) was malnourished. The MNA-SF could not be administered to six participants because of death, hospitalization or admission to a residential care center. Of the participants with (risk of) malnutrition, 44.3% (27/61) had a BMI < 23 kg/m², which is defined as underweight for older people . From thOf the total population, 32.9% 47/143) had a psychiatric multimorbidity. 70.2% (33/47) of people with psychiatric multimorbidity had (risk of) malnutrition. With regard to own nutritional assessment, 83.6% (51/61) of the participants with (risk of) malnutrition believed that they were well nourished and 78.7% (48/61) of this group indicated that they enjoyed eating moments, compared to respectively 92.1% (70/76) and 92.1% (70/76) of the participants with a normal score on the MNA-SF. (see Table 43 had a In order to detect people with (risk of) malnutrition, this study showed a PPV of 78,6%, a NPV of 60,7%, a sensitivity of 19.3% and a specificity of 96.0% for a weight evolution of ≥ 5% weight loss over six months. To detect malnutrition, our results showed respectively 33,3%, 98,4%, 71.4% and 92.3%. (see Table These results show that weight evolution in people over 70 living at home is a poor predictor in screening for (risk of) malnutrition. Compared to a validated screening tool, the MNA-SF, a weight loss of 5% or more appears to have a sensitivity of only 20% in detecting (risk of) malnutrition. However, a high specificity is observed (96.0%). A possible explanation for the low sensitivity is that the reduction in food intake is already present before weight loss occurs. Severe weight loss would occur too late to function as a nutritional marker in the screening for (risk of) malnutrition in clinical practice . HoweverIn this study, the prevalence of malnutrition is 5% and 38% of the participants are at risk of malnutrition. In 2013, the Nutri Action II study reported a prevalence of 7% and 28% respectively among 819 older persons living at home in Belgium [When developing the MNA-SF as a screening tool, a sensitivity and specificity of 79.5% and 77.4% were described for a BMI < 23 kg/m² as compared to the results on the full MNA [Our results show that 70.2% (33/47) of people with psychiatric disease have (risk of) malnutrition. This observation supports the finding that the prevalence of (risk of) malnutrition appears to be higher in older persons with dementia or depression as compared to other co-morbidities [A strength of this study is that the predetermined sample size was achieved. In addition, due to the multidisciplinary design and the size of the study population, many different healthcare providers are involved in this study. Another strength of the study is the use of the MNA-SF, a validated and well-developed screening tool for malnutrition for older adults . In addiA limitation of the study is that we included the home nurses via a convenience sample without randomization. In addition, mainly patients from rural areas were included in this study. Home nurses reported that patients in cities were more reluctant to give their informed consent. This may affect the representativeness of the study population. Furthermore, there sample of home nurses was very diverse, which might compromise the homogeneity. A selection bias is possible when nurses did not complete the study for all their patients who met the inclusion criteria or because certain patient groups refused to participate. The nurses might have deliberately selected patients based on their expected nutritional status, or presented the study only to the more cooperative patient, resulting in a lower prevalence of (risk of) malnutrition. The inclusion of people with dementia might also complicate the assessment of certain questions. Finally, the results referring to the malnutrition category in this study should be interpreted with caution, as the sample size was calculated on the basis of the prevalence of (risk of) malnutrition.Weight evolution has a low sensitivity in screening for (risk of) malnutrition in people over 70 living at home as compared to the MNA-SF. In order to detect people with malnutrition, weight loss seems to have a considerable predictive value in this study.To reliably define sensitivity and specificity of weight loss in the screening of malnutrition, a larger population is required with a sample size calculated on the basis of the prevalence of malnutrition.Since the MNA-SF is considered to be the best screening tool for malnutrition in community-dwelling older adults, it is interesting to make this screening tool more widely known among primary care providers. This way, the focus will shift from only monitoring weight evolution to a better, more comprehensive screening. resulting in fewer false negatives. A study into how the MNA-SF can be efficiently implemented in primary care, whether or not multidisciplinary, could provide an added value.Below is the link to the electronic supplementary material.Supplementary Material 1


What this study adds: Electrophysiologic and behavioral assays demonstrate that Mg2+ increases the efficacy of oxytocin; oxytocin efficacy is limited by Mg2+ availability. Clinical significance: Modulating Mg2+ levels may enhance oxytocin efficacy for pain, other uses, and endogenous processes.What is already known: Mg2+) concentration is critical to the activation of the OTR, and a low serum Mg2+ concentration is predictive of a migraine headache. We, therefore, examined the functional impact of Mg2+ concentration on OT-OTR binding efficacy using two complimentary bioassays. Experimental Approach: Current clamp recordings of rat trigeminal ganglia (TG) neurons measured the impact of Mg2+ on an OT-induced reduction in excitability. In addition, we assessed the impact of Mg2+ on intranasal OT-induced craniofacial analgesia in rats. Key Results: While OT alone dose-dependently hyperpolarized TG neurons, decreasing their excitability, the addition of 1.75 mM Mg2+ significantly enhanced this effect. Similarly, while the intranasal application of OT produced dose-dependent craniofacial analgesia, Mg2+ significantly enhanced these effects. Conclusions and Implications: OT efficacy may be limited by low ambient Mg2+ levels. The addition of Mg2+ to OT formulations may improve its efficacy in reducing headache pain as well as for other OT-dependent processes. Background and Purpose: The intranasal administration of oxytocin (OT) reduces migraine headaches through activation of the oxytocin receptor (OTR). Magnesium ion (Mg Thus, alterations of serum or exogenously applied Mg2+ levels should play a critical role in OTR activity and consequently the physiological and psychological functions listed above.Oxytocin (OT) is a nine-residue, cyclized peptide which, through to the oxytocin receptor (OTR), acts as both a hormone, regulating diverse processes such as glucose metabolism, social bonding, lactation, and uterine contraction, as well as a neurotransmitter, modulating neural processes including pain ,2,3,4. IR for OT ,12,13. RR for OT  publishe2+ levels strongly correlate with the frequency of headache attacks in patients with migraine [2+ control of OT binding has not been adequately examined, particularly with regard to the function of OTR activity and pain. The purpose of this study was, therefore, to examine the impact of Mg2+ on OT-OTR binding efficacy by examining these effects in neuronal electrophysiology and pain behavior. The tools selected to address our question included both current clamp experiments on freshly dissociated rat trigeminal ganglia (TG) neurons to determine OT effects on neuronal excitability as well as the in vivo impact of the addition of Mg2+ to intranasally administered OT in a rat model of craniofacial pain.Our previous work showed that OT decreases craniofacial pain in rodent models and headache severity and frequency in patients with migraine . Not surmigraine ,16,17. H2+ on OT-OTR binding efficacy by examining the effects on two key physiologic assays. We have previously demonstrated that OTR levels in trigeminal neurons are dependent, in part, on the presence of inflammatory cytokines [The objective of this study was to examine the impact of Mgytokines . TherefoAll animal care and experimental procedures complied with the laws of the United States and regulations of the Department of Agriculture and were approved by the Stanford University  Institutional Animal Care and Use Committee, in accordance with the 2011 National Institute of Health Guide for the Care and Use of Laboratory Animals. Animal studies are reported in compliance with the ARRIVE guidelines . Ethical permission (A3213-01 on 3 November 2020)2+ effects. Initial sample sizes were approximated by Power analysis, with animals assigned to groups randomly. Drug treatment experiments were conducted in a blinded fashion.Rats  were maintained two per cage in a controlled environment (temperature: 21.5 ± 4.5 °C/relative humidity: 35–55%) under a standard 12 h light/12 h dark lighting cycle . Cage changes occurred twice a week, using standard bedding. Food and water were provided ad libitum. Estrogen levels have been shown to drive OTR expression levels and so could drive substantial variability in response to OT treatment. Thus, we chose to use male animals for these studies to minimize this factor. We are currently pursuing separate experiments intended to explore this issue with regard to MgOT  was dissolved in distilled water as 1 mM stock and diluted for external solutions. Different concentrations of OT  were applied from the reservoir using gravity feeding through a 27G tip-blunted needle with an opening placed about 200 µm away from the recorded cell. The stream of solution covered the cell well when the switch was turned on. The cells were physically stable during perfusion.2+. Each solution was coded by the sponsor and the experimenter performed the experiment in a strictly blinded manner, including drug administration and data analysis.The appropriate amount of test compound was accurately weighed out using a calibrated electrical balance and placed into microcentrifuge tubes. Solutions were prepared for an administration volume of 50 μL containing vehicle or one solution for one of five doses of OT  plus or minus 300 mM magnesium citrate. These doses and concentrations were selected based on the results of prior studies ,19,20. TBriefly, rats  were placed in an anesthesia chamber and anesthetized with 2.5% isoflurane. Prior to TMJ injection, the rat’s mouths were propped open to palpate the target area. In this position, an oval-shaped groove located in the center of the cheek and above the mandible can be distinctly felt. With the syringe positioned at a 30-degree angle from the rat’s cheek, the tip of the needle was inserted just under the articular disc (approximately 1.5 mm in diameter and 1.0 mm deep). Thereafter, 50 µL of CFA  was injected (1 mL syringe with a 25G 5/8-inch needle) into the left TMJ to produce robust and prolonged orofacial inflammation. After CFA injection, rats were returned to home cages. Approximately 24 h later, rats were euthanized by decapitation after induction of deep anesthesia with isoflurane.w/v, final concentration) 0.1% trypsin , 0.1% collagenase Sigma, C1764), and 0.01% DNase  diluted in Dulbecco’s Modified Eagle Medium/Nutrient Mixture F-12 (DMEM/F12) . The tissue pieces were then incubated at 32 °C with a water bath for 55 min. Following digestion, tissue fragments were mechanically dissociated using a series of glass Pasteur pipettes with decreasing internal diameter. Dissociated cells were centrifuged at 180× g for 3 min, the supernatant was removed, and the cells were gently re-suspended in an external recording solution. Cells were then plated onto poly-l-lysine  coated cover slips , and Glucose (10), pH adjusted to 7.3–7.4 using HCl, with or without 1.75 mM MgCl2. The electrode internal solution was composed of (in mM) KF (120), HEPES (10), ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) (11), CaCl2 (1), MgCl2 (1), KCl (10), and KOH (11), pH adjusted to 7.3–7.4 using KOH. Patch-pipettes were fabricated from 1.5 mm outside diameter (OD) borosilicate capillary glass  using a micropipette puller . NaCl, HEPES-Na, KCl, CaCl2, Glucose, HCl, MgCl2, KF, HEPES, EGTA, KOH were purchased from Sigma . Glass pipettes filled this intracellular saline with a resistance of 3–5 MΩ. Whole-cell patch recordings had series resistances of <25 MΩ after whole-cell configuration and were periodically checked with the seal test voltage step  to monitor series resistances throughout the recordings. Hyperpolarizing current pulses  were delivered every 5 s throughout the experiment, unless otherwise specified, in order to monitor membrane input resistance and stabilize membrane potential in control external solution.Whole-cell voltage-clamp recordings were performed using the MultiClamp 700B amplifier  and analyzed offline with pCLAMP10.4 software . The external solution was composed of (in mM) NaCl (130), N-2-Hydroxyethylpiperazine-N’-2-Ethanesulfonic Acid (HEPES)-Na (10), KCl (5), CaCl2+ was applied for 2–5 min until the membrane potential stabilized further (on a new level) for at least 10 s. Measurement of change in membrane potential: After successful current clamp recording, the effect of the vehicle external solution application to cells on membrane potential was measured. After the membrane potential had stabilized for at least 10 s, a solution containing OT plus or minus 1.75 mM Mg® hair removal cream; Church & Dwight Co., Ewing, NJ, USA) and blackened ) cheek were determined. Latency to withdrawal response was used as an indicator of nociceptive responsiveness. We have previously demonstrated, using single-fiber peripheral nerve recordings, that low intensity (slow ramp) skin heating evokes withdrawal responses mediated by the activation of C- (unmyelinated) nociceptive fibers; higher intensity skin heating (rapid ramp) selectively elicits responses mediated by A-delta (myelinated) thermonociceptors [Rats  were used and treated with CFA injection into the TMJ as described above in order to produce a robust inflammation of trigeminally innervated tissue. Approximately 24 h after CFA injection, withdrawal latencies in response to noxious heat applied to the depilated . They were then placed on a heating pad in a supine position as the anesthesia was continued with a nose cone. This horizontal position of the head was maintained throughout the procedure preventing drainage of the drug solution to the trachea and esophagus. The total volume of 50 μL solutions was administered by pipette in 6–7 μL drops in alternating naris every two min, over a total of 14 min. The drop was placed at the naris opening while occluding the opposite naris allowing the animal to snort the drop into the nasal cavity. The rats were allowed to wake up in a separate cage on a heating pad. Rats were then returned to their home cage. Withdrawal latencies in response to A-delta or C fiber cheek stimulation were then remeasured at 60 min following dosing. At the end of the testing session, rats were euthanized by COWithdrawal latencies in response to thermal stimuli (noxious heat) were recorded as an index of thermal pain sensitivity. Increased withdrawal latencies were considered indicative of analgesia/anti-nociception.p < 0.05. Statistical analysis was undertaken only for data sets where each group size was at least n = 5. All results were analyzed using the GraphPad Prism 9.0 software .All data are presented as means ±SD with significance set at 2+. Sidak’s multiple comparison test was used to determine differences at individual concentrations. Significance was set at p < 0.05.Data were acquired using Clampfit—V10.4, Molecular Devices  and data sheets were constructed in Excel (Microsoft) and GraphPad Prism Software. Two-way ANOVA were performed to compare the overall significance of the difference between OT and OT + Mg2+ would significantly increase that response as determined by a significant difference between dose-response curves. Sidak’s multiple comparison tests were used for subsequent pairwise comparisons to pretreatment latencies.All data are expressed as mean withdrawal latency ±SE at 60 min post-dosing. Data generated during the testing of each fiber type  were analyzed, tabulated, and graphed separately. Statistical analyses were conducted using GraphPad Prism statistical software. All tests were conducted at the 0.05 level of statistical significance. Data generated were assessed using separate 2-way repeated-measures ANOVAs to determine if nasal OT produced dose-dependent significant increases in withdrawal latencies for A-delta or C fiber mediated responses and whether the addition of Mg2+, perfusion of cells with vehicle increased membrane potential insignificantly from −59.4 ± 1.9 mV to −60.6 ± 1.9 mV . 2+ resulted in the hyperpolarization of membrane potential ). A post-hoc multiple comparison (Sidak’s) test showed significant difference between OT and OT + Mg2+ groups at 1, 3, 10 (p < 0.05), and 1000 nM OT concentrations (p < 0.05).After a successful current clamp of TG neurons, the vehicle was applied as a control to the external solution. Both with or without 1.75 mM Mgotential B. While tial  and −9.3 ± 1.2 mV (n = 7 for 3 nM OT), respectively ). A post-hoc multiple comparison (Sidak’s) test showed a significant difference between OT and OT + Mg2+ groups at 1 (p < 0.05) and 3 nM OT concentrations (p < 0.05).In fact, while 1 or 3 nM OT had a minimal membrane potential effect (−1.4 ± 1.6 mV (n = 6) and −2.5 ± 0.6 mV (n = 6) hyperpolarization for 1 and 3 nM OT, respectively), the addition of 1.75 mM MgClectively D. Two-wa2+ however, produced a significant  increase in withdrawal latency compared to efficacy in the absence of Mg2+ for both A-delta (p < 0.05) between OT and OT + Mg2+ for A-delta testing at OT doses of 0.5, 1.0, and 32 μg OT; C-fiber responses were significantly different at 0.5, 4.0, 8.0, and 32 μg OT.Baseline testing revealed stable head withdrawal response latencies for A-delta (2.6–3.2 s) and C-fiber (7.5–8.1 s) radiant heat stimulation of the cheek A,B. The  A-delta A and C-f A-delta B testing2+ for OT’s high affinity for its receptor has long been known [2+ coordination site has been elucidated in the high-resolution cryo-electron microscopy structure of OT bound to its receptor, revealing that OT and OTR together form an octahedral Mg2+ coordination site between the receptor and ligand [2+ control of OT binding has not been adequately examined, particularly with regard to how Mg2+ levels could affect the impact of OT-OTR binding on pain as well as other phenomena. The results of the second messenger study described in [2+ is an essential cofactor for full OT-OTR agonism and that Mg2+ concentration-dependently increases Gq and G11 activation in OTR-transfected HEK cells. Interestingly, this study also demonstrated that OT-OTR binding did not reach maximal efficacy at physiologically relevant Mg2+ concentrations [2+ significantly enhanced this effect, implying a supportive impact of Mg2+ on OT craniofacial analgesia. In a demonstration of this support, while intranasal application of OT produced dose-dependent craniofacial analgesia, the addition of 300 mM Mg2+ to the administered OT significantly enhanced this analgesia.The requirement of Mgen known . More red ligand . Howeverribed in  demonstrtrations . Consist+ channel (Kv) current density [2+ to the applied OT in the same concentration range used in the second messenger study produced a significant increase in the degree of hyperpolarization of the membrane. In the absence of Mg2+, the maximal efficacy of OT is not reached, indicating the necessity of Mg2+ for the full agonism of OT. Interestingly, while the efficacy of the highest OT dose (32 μg) demonstrated a decrease in efficacy when compared to lower doses, this inversion was prevented by the addition of Mg2+. These findings indicate that the addition of Mg2+ produces a more robust decrease in cell excitability, consistent with a stronger analgesic effect than that observed with OT alone.The trigeminal nerve provides pain signaling from the head to the central nervous system for the perception of craniofacial pain. Thus, decreases in the excitability of these neurons should produce decreases in craniofacial pain sensitivity. The results of the current study are consistent with our previous finding  that OT  density . As with2+ to OT significantly enhances these analgesic effects. Previously, intravenous Mg2+ has been shown to abort continuous migraines and, when given as an oral supplement, reduce their frequency [2+ induced increase in the affinity of OTR for endogenous OT, thereby decreasing the excitability of trigeminal nociceptive neurons. Similarly, we have hypothesized that the decrease in serum Mg2+ during pre-menstruation and menstruation might help explain the phenomena of menstrual migraine [Using autoradiography and tissue scintillation counts, we have previously demonstrated that radiolabeled OT, when applied nasally, concentrates in the trigeminal nerve and ganglia ,24; an arequency . We havemigraine .2+ and migraine, serum estrogen levels, which vary over the menstrual cycle, have been shown to drive OTR expression levels [2+ and estrogen, it is likely that the effects of OT in females may vary significantly from those in males [2+ on OT analgesia in females across the menstrual cycle.In addition to the menstrual cycle effects on Mgn levels ,27 and hn levels . The varin males . We are 2+ produced shorter withdrawal latencies compared to the OT group without Mg2+. One explanation for this observation is based on our preliminary electrophysiological studies that show 1.75 mM Mg2+, in the absence of OT, is in fact, depolarizing in some cells. Thus, with a very low concentration of OT, it is likely that this depolarizing effect overwhelms any minimal hyperpolarizing effect of the OT. Interestingly, while the efficacy of the highest OT dose (32 μg) demonstrated a decrease in efficacy when compared to lower doses, this inversion was prevented by the addition of Mg2+. In a separate ongoing study (and so not directly comparable), we have similarly found that 128 μg demonstrates a significant drop in efficacy compared to lower doses that were preventable by the addition of Mg2+. Inverted U dose responses have been widely reported for various systems, including social recognition [2+ to an OT formulation should allow the use of higher doses, overcoming this barrier for a number of indications. The second messenger study by Meyerowitz et al. [The lowest OT dose (0.5 μg), supplemented with Mgognition , and, veognition . Althougz et al.  showed t2+ is required for the full agonism of OT and that, for pain and in many other therapeutic or disease settings, the efficacy of OT may be limited by the availability of Mg2+. Thus, the addition of Mg2+ to OT formulations or the development of novel OT analogs based on recently elucidated OTR structural biology [2+ may enable enhanced OTR efficacy.Taken together, the results of these two sets of experiments suggest that Mg biology  that obv


Cross-Modal Hashing (CMH) retrieval methods have garnered increasing attention within the information retrieval research community due to their capability to deal with large amounts of data thanks to the computational efficiency of hash-based methods. To date, the focus of cross-modal hashing methods has been on training with paired data. Paired data refers to samples with one-to-one correspondence across modalities, e.g., image and text pairs where the text sample describes the image. However, real-world applications produce unpaired data that cannot be utilised by most current CMH methods during the training process. Models that can learn from unpaired data are crucial for real-world applications such as cross-modal neural information retrieval where paired data is limited or not available to train the model. This paper provides (1) an overview of the CMH methods when applied to unpaired datasets, (2) proposes a framework that enables pairwise-constrained CMH methods to train with unpaired samples, and (3) evaluates the performance of state-of-the-art CMH methods across different pairing scenarios. Information retrieval refers to obtaining relevant information from a dataset when prompted by a query. When a dataset comprises samples from different modalities such as text, images, video, and audio, this field is known as Multi-Modal Information Retrieval (MMIR). Research towards MMIR methods is gaining considerable interest due to the expansion of data, resulting in a need for efficient methods capable of handling large-scale multi-modal data ,2,3,4,5.Where retrieval speed and storage space are considered top priorities, Cross-Modal Hashing (CMH) networks have recently been favoured over other traditional retrieval methods due to the computational efficiency and compactness that comes with the binary representations produced by hash-based methods ,7. CMH nRecent state-of-the-art CMH methods include Deep Cross-Modal Hashing (DCMH) , AdversaThe data most often used during training of information retrieval networks are paired, e.g., there is one-to-one or one-to-many correspondence between the text and image samples being used. However, such paired data are not always present in real-world data, and often constructed for training machine learning models. Unpaired data where no relationship is given between text and image samples are a common scenario present in the real world, which is not currently accounted for in many proposed CMH methods. Once unpaired samples are introduced into the data being used, pairwise-constrained methods cannot process such unpaired data in their baseline configuration and could therefore be unsuitable for real-world use cases where the data to be used are unpaired.This paper proposes a framework that facilitates the use of unpaired data samples for the training of CMH methods. The proposed framework can be employed to enable CMH methods to include unpaired samples in the learning process. The contributions of this paper are as follows.A comprehensive overview of CMH methods, specifically in the context of utilising unpaired data. The current state of CMH is surveyed, the different pairwise relationship forms in which data can be represented are identified, and the current use or lack of unpaired data is discussed ,13,14. HA new framework for Unpaired Multi-Modal Learning (UMML) to enable training of otherwise pairwise-constrained CMH methods on unpaired data. Pairwise-constrained CMH methods cannot inherently include unpaired samples in their learning process. Using the proposed framework, the MIR-Flickr25K and NUS-WIDE datasets are adapted to enable training of pairwise-constrained CMH methods when datasets contain unpaired images, unpaired text, and both unpaired image and text within their training set.Experiments were carried out to (1) evaluate state-of-the-art CMH methods using the proposed UMML framework when using paired and unpaired data samples for training, and (2) provide an insight as to whether unpaired data samples can be utilised during the training process to reflect real-world use cases where paired data may not be available but a network needs to be trained for a CMR task.This paper is organised as follows: The critical step to conducting the task of CMH retrieval is to establish and learn a common latent subspace onto which features from different modalities can be mapped ,16. ThisHamming distance sorting. When comparing two binary string hash codes, hamming distance refers to the number of bits that are different between the two codes, where a short hamming distance represents similarity and a long hamming distance represents divergence. Hamming distance sorting can be used as the nearest neighbour approach, where the hamming distances of the query sample relative to the samples in the retrieval dataset are obtained and ranked. The top samples in the formed rank would be the samples to be retrieved. Hamming distance sorting is computationally efficient and therefore meets the aim of hashing-based retrieval, that being fast query speeds.Hash table retrieval. Hash table retrieval aims to obtain a reduction in the number of distance computations needed when performing the retrieval task. This reduction is achieved through hash tables which sort samples into buckets according to their similarities. Samples closest in similarity will be placed in the same bucket, whereas divergent samples will be placed in different buckets. When a query is made, the most similar bucket that is relative to the query will be selected as the retrieval candidate. By only performing similarity computations among the hash tables and the hash table candidate contents, computing the similarity of the rest of the dataset is avoided.This section presents a classification of multi-modal data in terms of pairwise relationships. The discussion will focus on information retrieval, however the provided classification can be applied to other multi-modal applications. The pairwise relationship of the samples in a dataset dictates the approach to be employed when training a network for an information retrieval task. If pairwise relationships exist, these can be leveraged for improved learning of the task at hand. If pairwise relationships do not exist, i.e., the dataset is unpaired, the approach to designing multi-modal methods for such data will be different. Therefore, it is important to identify the relationship type of the data in use to address the task appropriately. The pairwise relationships are illustrated in 1–1 Paired Samples. This describes a relationship when a sample from one modality  has its direct counterpart in another modality  as seen in 1–Many Paired Samples. This refers to a relationship where a sample  has more than one counterpart in another modality  as shown in 1–1 Aligned Paired Samples. In the case of having more than two modalities, this relationship refers to samples with an aligned one-to-one pairwise basis across the different modalities in the dataset. For example 1–Many Aligned Paired Samples. In the case of having more than two modalities, this relationship refers to samples with an aligned one-to-many pairwise basis across the different modalities present in the dataset. When considering Unpaired Samples. These are fully unpaired samples that are independent in their respective modality and have no direct counterpart in another modality as shown in x is mapped to hash code y. As discussed by Wang et al. [Learning to hash refers to learning a hash function g et al. , the folHash function. The hash function aims to generate hash codes such that nearest neighbour samples in the input space are the closest to each other within the hash subspace. Hashing-based methods have traditionally employed linear projection, kernels, spherical functions and a non-parametric function for their hashing functions [unctions ,24,25. Hunctions  for two unctions .Similarity measures. Similarity measures for the input space and the hash coding space need to be considered. Similarity functions for hashing are most commonly based on the distance between two given samples, which often comes from Euclidean distance. The similarity functions frequently used include the Gaussian function and cosine similarity. The similarity value for deep neural network-based hashing is usually binary, with 1 representing common semantic meaning and 0 otherwise. For the hash code space, hamming distance is commonly used: Let M is the bit length of the hash codes to be compared and Loss function. The main aim when employing the loss function for hashing purposes is to maintain the similarity of samples within the original input space when mapped to the latent subspace, i.e., the nearest neighbours in the subspace should also be the nearest neighbours in the original input space. A widely adopted technique for maintaining input-subspace similarity is pairwise similarity preserving [eserving , which aOptimisation. There are two main issues to be considered with deep hashing methods which call for optimisation. The first issue is the vanishing gradient problem  stemming from the sign function employed for learning to hash. The second issue is the high time complexity when dealing with large amounts of data [z) ≈z. of data . A commo of data , which cFollowing the basis set by Cao et al.  in theirData-independent methods tackle the task of learning to hash independently of the data in use, where the hash function is generally generated through random mapping. The characteristic approach to such a method is using Locality-Sensitive Hashing (LSH) . LocalitData-dependent methods make use of the information available in the dataset as training data to generate the hash function to be used, as opposed to data-independent methods which cannot leverage the information in the dataset for hash function generation. Being able to use this information generally results in improved performance. The following are some characteristic approaches to data-dependent methods: with Cross View Hashing (CVH)  the hashDeep hashing methods came as a result of the recent success of deep neural networks across a multitude of fields and are currently the category of cross-modal hashing methods which is receiving attention ,32,33,34Generalized Semantic Preserving Hashing (GSPH) proposed by Mandal et al.  identifiHu et al.  with theWen et al. , with thGao et al.  proposedRobust Unsupervised Cross-modal Hashing (RUCMH) proposed by Cheng et al.  introducLiu et al.  propose Adaptive Marginalized Semantic Hashing (AMSH) proposed by Luo et al.  introducFlexible Cross-Modal Hashing (FlexCMH) proposed by Yu et al.  leverageThis section describes the learning process of three CMH methods for information retrieval and the aspects which bind these methods to the use of paired samples. The methods Deep Adversarial Discrete Hashing (DADH) , AdversaDADH . The typical workflow of adversarial-based CMH methods is illustrated in AGAH . Similarly to DADH, AGAH follows the adversarial-based CMH workflow as illustrated in JDSH . The main contributions of JDSH include the construction of a joint-modal similarity matrix used for supervised hash code generation and the proposition of the Distribution-based Similarity Decision Weighting (DSDW) method used for strengthening the generated hash codes. The joint-modal similarity construction process starts with separate text and image cosine similarity matrices derived from pre-trained deep neural network feature extraction. The image modality similarity matrix i and text j, N is the total amount of data pairs, The methods DADH and AGAH at their core are adversarial networks. The adversarial step in both methods is based on using an image and text pair to construct a true feature originating from the modality to be processed and a fake feature obtained from the counterpart modality for learning. Therefore, if the sample to be processed is unpaired, the true and fake feature pair cannot be formed, thus introducing a pairwise constraint at the adversarial step. In the case of JDSH, the pairwise constraint resides in the formulation of the joint-modal similarity matrix https://github.com/MikelWL/UMML, accessed on 9 December 2022).To make CMH methods compatible with the processing of unpaired samples, a suitable approach must be employed to include unpaired samples in the datasets to be used. The need for a suitable approach is due to CMH methods often not being compatible with the processing of unpaired samples, as is the case with methods DADH, AGAH and JDSH as discussed in The unpairing process. Let X be a n is the number of image samples and i is the number of image features, and let Y be a n text samples and j text vectors. The dataset D to be unpaired is defined as UMML is needed because pairwise-constrained CMH methods do not support actual unpaired data, thus requiring the use of empty samples to enable unpaired scenario evaluations. Once these unpaired samples are fed to the method being trained, no semantic value will be present within the emptied samples, resulting in semantically unpaired training. The newly unpaired samples are finally bundled with the samples which have been kept paired, and the unpaired dataset variant is constructed. Note that only the training set of the dataset is made unpaired by the UMML framework, as the query/retrieval set is left unaltered to avoid using empty samples as queries/retrievals during testing.MIRFlickr-25K  containsNUS-WIDE  consistsThe experiments compare state-of-the-art cross-modal hashing methods for information retrieval and evaluate their performance in paired and unpaired data scenarios using the proposed UMML framework. These methods are: Adversary Guided Asymmetric Hashing (AGAH) , Joint-mTo evaluate the performance of the CMH models, the widely adopted  retrievaPerformance difference compares the results when training with unpaired samples to results when training with paired samples. Let This section presents the results of experiments conducted using the proposed UMML framework applied to facilitate unpaired learning using the DADH, AGAH and JDSH methods and the MIR-Flicker25K and NUS-WIDE datasets. The training performance of these CMH methods is evaluated across different sampling scenarios: unpaired images, unpaired text, a combination of unpaired images and text, and random sample discarding. The abovementioned methods are also compared to other unpaired CMH methods that can learn unpaired data and thus do not require the UMML framework. Finally, the performance of the most promising method, DADH, is investigated at a more granular level that involves analysing DADH’s performance across each class of the MIR-Flickr25K dataset.Image to text Dataset impacts the performance of models. Different datasets provide different behaviours when unpaired samples are introduced into the training set. With MIR-Flickr25K, DADH and AGAH see different patterns of performance decrease for the ((2)Percentage of Unpairing may impact performance. For MIR-Flickr25K, the performance of methods DADH and AGAH for the  of samples are discarded, the remaining 8000 pairs will be utilised for training. Training when discarding 20% of pairs can then be compared to training with a set of which 20% of samples are unpaired. This comparison is illustrated in Results. Evaluation results when incrementally discarding samples from the paired training set, along with the random baseline performance results (labelled as Random) are presented in In terms of sample discarding, DADH and AGAH benefit noticeably from additional training data as shown in Although the DADH, AGAH and JDSH methods were not developed for unpaired training, using the UMML framework, training with unpaired samples resulted in improved results in 53 of the 90 cases evaluated. The performance improvement when including unpaired samples in the training set when compared to discarding the samples outright was more substantial the more limited the amount of paired data was available in the dataset. Therefore, strategies for adapting CMH methods to efficiently train with unpaired samples are needed, particularly when limited paired data is available and unpaired data need to be utilised for improving the learning of the model.The following is a comparison between the pairwise-constrained methods: DADH, AGAH and JDSH when using the proposed UMML framework to enable these methods to learn from fully unpaired samples; and the unpaired CMH methods: Adaptive Marginalized Semantic Hashing (AMSH) , Robust AMSH and FlexCMH are supervised methods that shuffle the training data to create unpaired sample behaviour. RUCMH is an unsupervised method that is independent of pairwise relationships. For the methods DADH, AGAH and JDSH, the 50% image and 50% text UMML unpairing approach is used as discussed in For AMSH, RUCMH and FlexCMH, the results in their respective publications are used for this comparison because the source-code for these methods are not publicly available. For a full specification regarding the training parameters of AMSH , RUCMH  and FlexAs shown in The objective of this experiment is to evaluate the performance of each class in MIR-Flickr25K when training with unpaired samples using DADH. Evaluations were made on a class-by-class basis across the 24 classes in the dataset, where three training set pairing scenarios were evaluated: fully paired, 80% of the training text being unpaired, and 80% of the training images being unpaired.–Unpaired data can improve the training results of CMH methods. Furthermore, if data from both the image and text modalities are present in the training set, initially pairwise-constrained CMH methods can be trained on fully unpaired data.–The extent to which unpaired data are helpful to the training process is relative to the amount of paired samples. The more scarce the paired samples available, the more helpful it can be to use additional unpaired samples for training.–The performance of the models showcased when using unpaired samples for training is dependent on the modality of the unpaired samples, the dataset being used, the class of the unpaired data, and the architecture of the CMH algorithms. These factors influence whether unpaired samples will be helpful to the training process.–The proposed UMML framework adapts the dataset to enable pairwise-constrained CMH methods to train on unpaired samples. When using UMML to enable DADH, AGAH and JDSH to train with unpaired samples, it was observed that the methods perform well when training with unpaired samples. This suggests that further improvements may be observed if the architectures of these methods are adapted to train on unpaired data.This paper explores the topic of Unpaired Cross-Modal Hashing (CMH) and the capabilities of state-of-the-art CMH methods with regards to learning from unpaired data in the context of information retrieval. The UMML framework has been proposed to enable pairwise-constrained CMH methods to learn from unpaired data. Through UMML, experiments have been conducted using DADH, AGAH and JDSH with paired and unpaired sample variations of MIR-Flickr25K and NUS-WIDE datasets. Evaluations to determine how unpaired data affect performance were carried out. Below is a summary of the main observations:With the findings obtained in this study, future works include extending the proposed UMML framework to adapt methods to training with unpaired samples at an architectural level. Future work also includes applying the UMML framework using data from case studies provided by industry.


Natural sciences and engineering use the related interdisciplinary concept of biomimesis. Both neuroscience and humanities have critiqued the notion of representation as mental simulation of objective reality in the individual brain, in favor of non-solipsistic, multidimensional, and dynamic frameworks, including paradigms of distributed mind and 4E  cognition.Both neuroscience and the humanities seek to understand the nature of representation and simulation, yet seldom in dialogue or collaboration. Neuroscience tries to assign metrics of brain activity to specific representations of the outer world. For instance, a flower can be represented by population level activity in the ventral visual stream, or in terms of the motor plans required to grasp it in parietal, premotor and motor areas. It is also represented in much richer associations spanning activity and computations across systems and networks. The humanities encompass what ancient Greeks named In Search of Lost Time, is prized for its introduction of a potentially infinite wealth of associations and mental states, beyond quantifiable data.Scaling issues complicate interdisciplinary efforts to theorize representation. In neuroscience, the scale might be at the level of the neural coding of a transient event (a briefly flashed stimulus in a laboratory experiment), or of carefully controlled events unfolding over longer time scales . In literature, even a single metaphor, such as Proust's madeleine in Research into representation benefits from dialogue and collaboration between the neurosciences and the humanities, through the construction of conceptual and/or experimental bridges. This Research Topic encourages neuroscientists to engage with mimesis, and humanists to engage with systems neuroscience as a portal toward a biological or phenomenological understanding of representation in embodied, experiential, and social senses. Both neuroscientists and scholars in the humanities may ask: How do neurobiological conceptions shed light on representation in mimetic terms? How do neurosciences and humanities visualize or describe representation itself, as a dimension of mental, embodied, and social functioning? Knowing that representation of the thoughts and intentions of others may be grounded in the sensorimotor transformations of distributed circuits in the brain, what new questions can we ask about mimesis? How does network neuroscience account for that? How might brain machine interface shape humans' representation of the internal and external world? These questions open a new frontier in integrative neuroscience, a neurohumanities frontier that calls for integration, or mediation, of the methods, assumptions, and practices. Bridging these two fields, which may initially appear as extremes, is achieved in this collection through questions aimed at intersubjective cognition, bilateral neuroscientific and humanistic analyses of texts and art, and neurocognitive computational models of representation.Gambino and Pulvirenti present imagination as a neurocognitive framework for understanding embodied simulation. Embodied simulation, neuroscientifically understood through activation of sensorimotor mechanisms, may occur during reading in which the reader may cognitively “imitate” or perform “world construction” of the literary text they are immersed in. The authors argue that scientific research may benefit from literature's dynamic and embodied simulation-based interpretation of imagination when formulating questions about cognitive faculties such as perception, imitation, and simulation.Agarwal, who presents an analysis of complementary and alternative medicine (CAM) providers' practices in their treatment of breast cancer survivors. In this original research study, recruited CAM providers undergo semi-structured interviewing that seeks to reveal how providers “tune in” to their patients' internal states and “co-create experiences of pain” through embodied simulation, imagination, and intentional vulnerability. The article then interprets the study's findings within the context of the mirror neuron system. It describes how mimetic self-reflexivity and intersubjectivity may inform research on self-recognition and self-other discrimination with implications for complementary healing practices among breast cancer survivors at risk of post-surgical pain.Embodied simulation is then explored by Hipólito rejects the common analogy made between neurocognitive activity and computers, arguing that properties of the models used in computational cognitive neuroscience  do not literally exist in the brain. The author presents Dynamic Causal Modeling (DCM) and Dynamic Systems Theory (DST) as alternative approaches for dynamically describing neurocognitive activity.Holhol et al. present the importance of ‘cognitive artifacts' as essential tools for cumulative culture and cultural innovation. According to the authors, cognitive artifacts are external artificial devices designed to serve a representative function, a simple example being a map, and more complex examples being literary oral formulae or mathematical proofs. Through three examples from cognitive history, namely, Homerian epics, Euclidean geometry, and Roman law, the authors describe how artifacts shape ‘cognitive niches' for innovation across historical timescales.Tying together cognition, cultural transmission, and representation, Reilly argues that neuroscientific visualizations of mental functioning such as Ramón y Cajal's pen and ink renderings of pyramidal neurons and glial cells fall within the mimetic tradition and bring non-realist techniques to bear in visualization of brain and mind. Once new methodological links between humanities and neuroscientific visualizations of mental functioning are forged, aesthetic works in the humanities such as Lucretia Martel's film “The Headless Woman” may shed new light on representational strategies in neuroscience to make otherwise invisible psychic phenomena observable.Rodríguez Villar explores how structural representations of time in theater can be used as a lens for investigating human perception and cognition in the dramatic form of the Autos sacramentales by the early modern Spanish playwright Pedro Calderón de la Barca. The Christian understanding of time and the characters' perceptions of time presented in this text is linked to neuroscientific evidence of how the human brain processes time, such as circadian rhythms and hippocampal-driven memory encoding.Representation in these six articles extends beyond the symbol processing that was long interpreted as an Archimedean point in neuroscience. They ask new questions about both science and arts as finely honed mimetic systems of embodied sense-making, overlapping with world-making. They reflect broad potential for integrated and intersectional methodologies bridging neuroscience and humanities.MI, DJ, and LEW functioned as editors of the associated Research Topic, Representation in neuroscience and humanities. JU assisted the editors. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Male Tsumura-Suzuki Obese Diabetes (TSOD) mice, a spontaneous metabolic syndrome model, develop non-alcoholic steatohepatitis and liver tumors by feeding on a standard mouse diet. Nearly 70% of liver tumors express glutamine synthetase (GS), a marker of hepatocellular carcinoma. In contrast, approximately 30% are GS-negative without prominent nuclear or structural atypia. In this study, we examined the characteristics of the GS-negative tumors of TSOD mice. Twenty male TSOD mice were sacrificed at 40 weeks and a total of 21 tumors were analyzed by HE staining and immunostaining of GS, liver fatty acid-binding protein (L-FABP), serum amyloid A (SAA), and beta-catenin. With immunostaining for GS, six (29%) tumors were negative. Based on the histological and immunohistological characteristics, six GS-negative tumors were classified into several subtypes of human hepatocellular adenoma (HCA). One large tumor showed generally similar findings to inflammatory HCA, but contained small atypical foci with GS staining and partial nuclear beta-catenin expression suggesting malignant transformation. GS-negative tumors of TSOD mice contained features similar to various subtypes of HCA. Different HCA subtypes occurring in the same liver have been reported in humans; however, the diversity of patient backgrounds limits the ability to conduct a detailed, multifaceted analysis. TSOD mice may share similar mechanisms of HCA development as in humans. It is timely to review the pathogenesis of HCA from both genetic and environmental perspectives, and it is expected that TSOD mice will make further contributions in this regard. We previously reported that male Tsumura-Suzuki Obese Diabetes (TSOD) mice, a spontaneous metabolic syndrome model, developed non-alcoholic steatohepatitis and liver tumors at a high rate after 8 months of age by feeding on a standard mouse diet ,2,3. TSOHepatocellular adenoma is a rare benign tumor of the non-cirrhotic liver that has been associated with oral contraceptive use in young women, steroid use, and type I and type III glycogenic disease . AccordiMost cases of HCA show a benign course, but hemorrhage and malignant transformation have been reported in rare cases ,8,9,10. According to the 2019 WHO classification, HCA is divided into four categories: HNF1α-inactivated HCA (H-HCA), inflammatory HCA (IHCA), beta-catenin-activated HCA (b-HCA), and β-catenin-activated IHCA (b-IHCA) ,16. OtheMutations in the HNFIA gene, which encodes HNF1α, a transcription factor involved in hepatocyte differentiation, result in the loss of protein expression in tumor cells. In immunostaining, antibodies against the liver fatty acid-binding protein (L-FABP), which is positively regulated by the HNF1A gene, are useful diagnostic markers. In this type of HCA, L-FABP is attenuated or shows as negative . The tumInflammatory HCAs account for 35–40% of all HCAs and are the most common subtype . MutatioMutations or deletions in the CTNNB1 (cadherin-associated protein B1) gene encoding β-catenin have been reported to cause activated WNT signaling and tumorigenesis in b-HCA. It is reported that b-HCAs account for 10% of all HCAs and that b-IHCAs, described below, account for 10–15% . Immunosb-IHCA is considered to have features of both IHCA and b-HCA and is at risk for malignant transformation ,22.In this study, we examined in detail the characteristics of GS-negative tumors that spontaneously develop in TSOD mice against the background of metabolic syndrome. We aimed to clarify the dissimilarities between these tumors and human hepatocellular adenomas based on histopathological and immunohistological analyses. The purpose of this study is to propose the utility of the TSOD mouse as an animal model that can help elucidate the natural history of HCA and its pathogenesis, which is still largely unknown.Grossly, there were no liver tumors in TSNO mice, while 19/20 (95%) of TSOD mice examined had one or more liver tumors. One section containing the largest tumor in each of the 19 grossly positive individuals and one largest section of the tumor-free individual were prepared for histopathological analyses. The 20 specimens from 20 individuals were observed microscopically, and all tumors of size ≥1 mm were evaluated. One to two tumors were identified in each section, and a total of 21 tumors were analyzed in detail. In immunostaining for GS, 15 (71%) tumors were GS-positive and six (29%) tumors were GS-negative.The histopathological characters of the GS-positive tumors were as previously reported ,23,24. TGS-negative tumors showed various histological findings mimicking human hepatocellular adenoma. Based on the histological and immunohistological characteristics, the six tumors examined in this study were classified into four types similar to those of human hepatocellular adenoma. The characteristics of each type are described below and listed in Two tumors (tumors 3 and 5) showed similar pathological and immunohistochemical findings to human HNF1 a-inactivated HCA. Hepatocytes showed trabecular structure, and individual cellular atypia was unremarkable. Some tumor cells contained small lipid droplets in the cytoplasm. An invasive growth pattern was not observed  A,B,G,H.Two tumors (tumors 2 and 4) showed similar pathological and immunohistochemical findings to human inflammatory HCA. Hepatocytes showed trabecular structure with dilatation of sinusoids. Pseudoglandular hepatocellular arrangements were occasionally observed, in addition to thick-walled vessels and sparse aggregation of inflammatory cells. An invasive growth pattern was not observed A,B,G,H. One tumor (tumor 1) shared the pathological and immunohistochemical findings of human HNF-1 alpha-inactivated HCA and inflammatory HCA. Pathologically, hepatocytes showed trabecular structure, and individual cellular atypia was unremarkable. There were no clear lipid droplets in the cytoplasm. Sinusoidal dilatation and inflammatory cell aggregation was not observed. An invasive growth pattern was not seen A,B. ImmuOne tumor (tumor 6) showed generally similar pathological and immunohistochemical findings to human inflammatory HCA A–D. HoweTwenty male TSOD mice and TSNO mice were fed on a standard mouse diet and sacrificed at 40 weeks of age. The livers were immediately removed and soaked in 10% neutral buffered formalin, cut surgically into 3-mm-wide whole sections, and the tumors were confirmed grossly. From each individual, one section containing the largest tumor was prepared and subjected to HE staining and immunohistochemical analysis of GS, L-FABP, SAA, and β-catenin. Tumors of size ≤ 1 mm microscopically were included for evaluation.All institutional and national guidelines for the care and use of laboratory animals were followed. Furthermore, this study was performed following the animal experiment guidelines specified in the Institute for Animal Reproduction , which strictly abides by the rules of guidance on animal research ethics from the International Association of Veterinary Editors’ Consensus Author Guidelines on Animal Ethics and Welfare. Approval code from the Experimental Animal Welfare Ethics Committee of Institute for Animal Reproduction is IAR-EAWEC-2021-2-61, which was approved on 18 January 2021. This article does not involve any studies with human subjects.This study revealed that TSOD mice spontaneously develop tumors similar to human HCA, in addition to HCC. HCA is defined as occurring in the normal liver, but a number of tumors with features similar to those of HCA have been reported in the context of alcoholic liver injury and other conditions, and are referred to by various names, including “HCA-like tumor”. The difference between HCA and HCA-like tumor is still inconclusive, as they are considered by some as different disease entities, and by others as having the same characteristics. The background liver of the TSOD mice studied in this study showed various degrees of NASH. In this sense, the term “HCA-like tumor” may be accurate. However, the biological and histopathological characteristics of HCA-like tumors are still unknown, which is why we compared liver tumors of TSOD mice with various subtypes of HCAs in humans.Interestingly, we observed the occurrence of liver tumors with various morphological and immunohistological features, including tumors that are similar to human HNF1 a -inactivated HCA, inflammatory HCA, and b-catenin-activated IHCA (b-IHCA). In humans, HCAs often appear as multiple tumors, and reports of different HCA subtypes occurring in the same liver have been observed. However, few human cases have been reported, and the diversity of patient backgrounds limits the ability to conduct a detailed, multifaceted analyses. TSOD mice are a spontaneous metabolic syndrome model with a background of obesity, hyperlipidemia, and diabetes mellitus under normal feeding conditions and without the need for special treatment, suggesting shared mechanisms with the development of HCA in humans.There are several reports of mouse models that developed HCA. For example, HCA developed in a mouse model of glycogen storage disease ,25 and lThe present analysis of 20 TSOD mice identified at least three subtypes of HCA sharing characteristics of multiple subtypes. Although the molecular basis for each HCA subtype in humans is well established and characteristic histological findings have been accumulated, the events that trigger the development of these tumors remain unclear. Unique to the TSOD mouse model, each subtype is represented by multifaced characteristics, including molecular biological information and immunological aspects with surrounding hepatocytes, that can be compared with each other. Formalin fixation was performed for all liver tumors in the present study. Simultaneous preparation of frozen specimens would enable additional molecular biological analysis and immune cell kinetics analysis.Among the liver tumors identified in this study, one tumor (tumor 6) contained a localized atypical focus within inflammatory HCA. This tumor may be a very useful subject for analysis of the malignant transformation of HCA. We have recently developed a new liver biopsy technique that enables liver tissue to be obtained from the same individual up to four times over time. Tumor 6 was a large tumor, sized approximately 3–15 mm. Targeted liver biopsy of a large liver tumor such as this over time may allow the collection of histological samples of HCA that have a high probability of malignant transformation over time. Analysis of the properties of such tumors over time at the molecular level would be expected to help elucidate the mechanism of the malignant transformation of HCA.As the pathogenesis of HCA becomes clearer, reports of unusual cases such as multiple occurrence or non-normal background liver are increasing. At this point it is timely to review the pathogenesis of HCA from both genetic and environmental perspectives, and it is expected the TSOD mice will make further contributions in such investigations.In conclusion, TSOD mice are expected to be used to analyze how the metabolic syndrome is involved in the development of HCA. In addition, long-term observation will help to elucidate the mechanism of the malignant transformation of HCA.