Mr. Nissen studies several areas, primarily focusing on how physical activity environments influence health in different populations, particularly suburban communities and marginalized groups. His research includes exploring wearable technology to monitor both physical activity and mental health, aiming to improve health outcomes through data-driven approaches. Additionally, he investigates how agricultural practices, specifically with barley, can improve resilience against climate stress brought on by climate change, which is vital for food security.
Key findings
In a study of Hispanic families, children were found to engage in about 60 minutes of vigorous physical activity daily, while their parents participated for around 30 minutes, showing a strong correlation between neighborhood appearance and physical activity levels.
In assessments of wearable devices, over 13,000 articles were reviewed, with only 222 meeting quality standards, indicating a need for higher quality data in tracking real-life physical behavior.
Barley plants with enhanced levels of the protein HvHSFA2 demonstrated improved heat tolerance, which could inform agricultural practices to combat climate change effects.
Frequently asked questions
Does Dr. Nissen study wearable technology?
Yes, he researches how wearable devices can monitor physical activity and their relationship with mental health.
What populations does Dr. Nissen focus on in his research?
He focuses on various groups, including Hispanic families, students, and patients with specific health conditions.
Is Dr. Nissen's work relevant to farmers?
Absolutely, his research on barley aims to improve crop resilience in the face of climate change, which is crucial for agricultural practices.
Publications in plain English
Applying AI in the Context of the Association Between Device-Based Assessment of Physical Activity and Mental Health: Systematic Review.
2025
JMIR mHealth and uHealth
Woll S, Birkenmaier D, Biri G, Nissen R, Lutz L +3 more
Plain English This research paper reviews studies that use wearable technology, like fitness trackers, to monitor physical activity and assess mental health conditions such as stress and depression. Out of over 11,000 studies, 49 were selected, showing that many focused on metrics like step count and often included small groups of participants, with more than half having under 100 people involved. The findings highlight the potential of combining AI with wearable data to improve mental health prediction and management, but point out significant gaps in study quality and data collection that need to be addressed for these tools to reach their full potential.
Who this helps: This helps patients, particularly those dealing with mental health issues.
Association between neighborhood environment and self-reported and objectively measured physical activity in Hispanic families.
2025
Frontiers in sports and active living
Nissen R, Fraga K, Woll A, Vega-López S, Krell-Roesch J +1 more
Plain English This study looked at how the surroundings of Hispanic families in South Phoenix affect their physical activity levels. Researchers found that children spend about 60 minutes a day in vigorous activities, while their parents engage in around 30 minutes, with better neighborhood appearance linked to more physical activity for kids. This is important because it highlights how safe and attractive neighborhoods can help families be more active.
Who this helps: This helps Hispanic families, urban planners, and community health workers.
Conserved heat shock factors HvHSFA2 and HvHSFA3 control barley heat stress memory through diverged mechanisms.
2025
Nature communications
Pratx L, Dakhiya Y, Nissen R, Purushotham P, Hoffie I +3 more
Plain English This study looked at how two specific proteins in barley, HvHSFA2 and HvHSFA3, help the plant remember past heat stresses and respond better to high temperatures. Researchers found that when these proteins were mutated, barley's memory for heat stress weakened, reducing its ability to handle heat. In contrast, increasing the levels of HvHSFA2 improved heat tolerance without harming the plant's growth. This matters because it offers a clear way to enhance heat resistance in barley and possibly other cereal crops, making them more resilient to climate change.
Who this helps: This helps farmers and agricultural scientists seeking to improve crop resilience in warmer climates.
Assessment of 24-hour physical behaviour in adults via wearables: a systematic review of validation studies under laboratory conditions.
2023
The international journal of behavioral nutrition and physical activity
Giurgiu M, Ketelhut S, Kubica C, Nissen R, Doster AK +7 more
Plain English This research looked at how well wearable devices (like fitness trackers) measure physical activity in adults by reviewing 545 laboratory studies from 1994 to 2022. The findings showed that most studies (73.8%) focused on measuring exercise intensity, while very few examined biological states or types of activity. Most studies were of low quality, and only 4.4% were considered to have low risk of bias, highlighting the need for better research methods and comprehensive validation in this area.
Who this helps: This helps patients and researchers who rely on accurate data from wearables to understand physical activity and health.
Quality Evaluation of Free-living Validation Studies for the Assessment of 24-Hour Physical Behavior in Adults via Wearables: Systematic Review.
2022
JMIR mHealth and uHealth
Giurgiu M, Timm I, Becker M, Schmidt S, Wunsch K +8 more
Plain English This study looked at the quality of research on wearable devices used to track physical activity in real-life settings. Out of over 13,000 research articles, only 222 met the necessary quality standards for inclusion. Most studies focused on measuring activity intensity, while far fewer assessed biological states or specific types of activities. Importantly, a large proportion of the studies (72.9%) had high methodological risk, indicating that many findings may not be reliable or valid.
Who this helps: This research benefits patients, doctors, and researchers by highlighting the need for better validation of wearable devices.
Drivers of productivity: Being physically active increases yet sedentary bouts and lack of sleep decrease work ability.
2021
Scandinavian journal of medicine & science in sports
Giurgiu M, Nissen R, Müller G, Ebner-Priemer UW, Reichert M +1 more
Plain English This study looked at how physical activity, sitting too long, and sleep affect students' feelings about their ability to work. The researchers found that being more physically active and getting up from sitting helped students feel more capable at work, while sitting for more than 20 minutes and not getting around 8 hours of sleep hurt their sense of productivity. These findings highlight the importance of staying active and having good sleep habits for improving work performance among students.
Who this helps: This helps students improve their work performance and productivity.
Four aspects of spiritual care: a phenomenological action research study on practicing and improving spiritual care at two Danish hospices.
2021
Palliative care and social practice
Viftrup DT, Nissen R, Søndergaard J, Hvidt NC
Plain English This study looked at how spiritual care is provided to patients in two hospices in Denmark, examining both patients' and staff's views and experiences. Researchers conducted 12 individual interviews and 9 focus group discussions, identifying four main areas of spiritual care: relationships, individuality, physical presence, and communication. They found that while staff were initially hesitant to talk about spiritual issues, they recognized the importance of initiating these conversations to better support patients in meeting their spiritual needs.
Who this helps: This helps hospice patients and their caregivers.
A comparison of the Sensory Profile scores of children with autism and an age- and gender-matched sample.
2013
South Dakota medicine : the journal of the South Dakota State Medical Association
Brockevelt BL, Nissen R, Schweinle WE, Kurtz E, Larson KJ
Plain English This study looked at how children with autism respond to sensory experiences compared to children without autism, focusing on kids aged 3 to 9 years. Researchers found that children with autism scored significantly differently in all areas of sensory processing, indicating they handle sensory information in ways that are distinct from their peers. This matters because understanding these differences can help improve support and interventions for children with autism.
Who this helps: This helps children with autism and their caregivers.
A survey of cleft team patient experience in obtaining dental care.
2009
The Cleft palate-craniofacial journal : official publication of the American Cleft Palate-Craniofacial Association
Becker DB, Lee F, Hill S, Nissen R, Huebener D +3 more
Plain English This study looked at how patients with cleft lip and/or palate, aged 7 to 12, experience getting dental care. Out of 374 eligible patients, 171 were interviewed, revealing that 84.8% had regular dental checkups, but those with private insurance were much more likely to receive care compared to those with Medicaid or no insurance. This is important because it highlights significant differences in access to dental care based on insurance, impacting the health and satisfaction of kids who need specialized care.
Who this helps: This helps patients and their families, especially those on Medicaid or without insurance.
Plain English This study looked at how certain small RNA molecules, called microRNAs, behave in developing mouse embryos. The researchers found specific patterns of expression for two microRNAs, miR-10a and miR-196a, which show similar patterns to genes that are important for body development. Notably, miR-196a was found to block the expression of a development-related gene called Hoxb8, highlighting its role in shaping how embryos form.
Who this helps: This research aids scientists working on developmental biology and may have implications for understanding developmental disorders.
Lesions of the diagonal band of broca enhance drinking in the rat.
2003
Journal of neuroendocrinology
Sullivan MJ, Cunningham JT, Mazzella D, Allen AM, Nissen R +1 more
Plain English This study looked at how a specific brain area in rats, called the diagonal band of Broca, affects drinking behaviors and the hormone vasopressin, which helps control water balance. Researchers found that rats with damage to this area drank more in response to dehydration compared to control rats, specifically increasing their water intake in reaction to certain conditions, but their regular drinking habits and urine output remained unchanged. This is important because it helps us understand how the brain regulates thirst and fluid balance, which could have implications for treating dehydration-related issues in humans.
Who this helps: Patients with conditions related to fluid balance and hydration.
Hypothalamic A14 and A15 catecholamine cells provide the dopaminergic innervation to the supraoptic nucleus in rat: a combined retrograde tracer and immunohistochemical study.
1999
Neuroscience
van Vulpen EH, Yang CR, Nissen R, Renaud LP
Plain English This study looked at where certain brain cells that release dopamine come from and how they connect to a part of the brain involved in hormone regulation. Researchers found that the main source of these dopamine-releasing cells in the hypothalamic supraoptic nucleus comes from small groups of neurons called A14 and A15. Specifically, they found these connections in six rats, confirming that the majority of dopamine signals for this function come from these specific areas.
Who this helps: This research benefits doctors and neuroscientists studying brain function and hormone regulation.
D221 in thymidylate synthase controls conformation change, and thereby opening of the imidazolidine.
1998
Biochemistry
Sage CR, Michelitsch MD, Stout TJ, Biermann D, Nissen R +2 more
Plain English This study examined the protein thymidylate synthase (TS) and how a specific part of it, called Asp-221, affects its ability to function. Researchers found that changing Asp-221 to another amino acid (specifically Asn-221) disrupts the protein's normal activity, with only a few variations allowing for function. They found that the interaction between Asp-221 and the cofactor is crucial for the protein to work properly, as it ensures the correct positioning for further chemical reactions.
Who this helps: This research benefits scientists developing drugs targeting cancer treatment by understanding how certain proteins work.
Regulation of spontaneous phasic firing of rat supraoptic vasopressin neurones in vivo by glutamate receptors.
1995
The Journal of physiology
Nissen R, Hu B, Renaud LP
Plain English This study looked at how certain brain cells in rats that produce the hormone vasopressin fire signals in a rhythmic way. Researchers found that nearly all tested vasopressin neurons responded strongly to a chemical called NMDA (27 out of 28 neurons), and also reacted well to other chemicals called AMPA and kainate. These findings suggest that a specific set of receptor mechanisms are crucial for maintaining this regular activity of vasopressin neurons, while similar neurons that produce oxytocin are mostly controlled by different receptors.
Who this helps: This helps researchers studying hormone regulation and could benefit patients with conditions related to vasopressin and oxytocin imbalances.
N-methyl-D-aspartate receptor antagonist ketamine selectively attenuates spontaneous phasic activity of supraoptic vasopressin neurons in vivo.
1994
Neuroscience
Nissen R, Hu B, Renaud LP
Plain English This study looked at how ketamine, a medication that blocks certain receptors in the brain, affects the activity of neurons that release the hormone vasopressin in rats. The researchers found that administering ketamine significantly reduced the rhythmic firing of these vasopressin-secreting neurons in 16 out of 19 instances, showing that ketamine effectively dampens their activity. This research matters because understanding how to control vasopressin neuron activity could have implications for treating conditions related to hormone regulation, such as those affecting fluid balance or blood pressure.
Who this helps: This benefits patients with hormone-related disorders, particularly those dealing with fluid and blood pressure issues.
[Functional treatment of surgically treated empyema of the knee joint].
1994
Der Unfallchirurg
Draijer F, Lorentzen T, Nissen R, Havemann D
Plain English This study looked at how patients with knee-joint empyema (an infection forming pus in the joint) recover after surgery. The findings showed that those who had surgery for knee-joint empyema experienced longer recovery times and worse outcomes compared to patients with less severe knee injuries, like skin wounds or punctures. This matters because it highlights the need for targeted treatment approaches based on the type of injury, which can help improve recovery for those affected.
Who this helps: Patients with knee-joint infections and their doctors.
GABA receptor mediation of median preoptic nucleus-evoked inhibition of supraoptic neurosecretory neurones in rat.
1994
The Journal of physiology
Nissen R, Renaud LP
Plain English This study looked at how a specific brain region called the median preoptic nucleus (MnPO) affects two types of hormone-producing nerve cells in rats, which produce vasopressin and oxytocin. The researchers found that stimulation from the MnPO generally decreased activity in vasopressin cells in 120 out of 139 cases and increased activity in oxytocin cells in only 51 out of 59 cases, showing that MnPO has a mostly calming effect on these hormones. Understanding this regulation is important because it could shed light on how our body controls water balance and social behaviors.
Who this helps: Patients with hormonal imbalances or disorders related to vasopressin and oxytocin.
Perinuclear zone and diagonal band lesions enhance angiotensin responses of rat supraoptic neurons.
1994
The American journal of physiology
Cunningham JT, Nissen R, Renaud LP
Plain English This study looked at how certain brain areas in rats affect the response of neurons that produce the hormone vasopressin when exposed to a substance called angiotensin II. Researchers found that damaging two specific areas in the brain increased the sensitivity of these neurons to angiotensin II: lesions in the diagonal band of Broca and the perinuclear zone led to a stronger reaction to the substance than normal. This matters because understanding these mechanisms could help improve treatments for conditions related to fluid balance in the body, such as hypertension (high blood pressure).
Who this helps: This research benefits patients dealing with blood pressure issues and doctors treating those conditions.
Membrane properties of organum vasculosum lamina terminalis neurons recorded in vitro.
1993
The American journal of physiology
Nissen R, Bourque CW, Renaud LP
Plain English This study looked at specific neurons in the brain, known as OVLT neurons, taken from rats to understand how they respond to different electrical signals and changes in their environment. Researchers found that a large majority of these neurons (32 out of 34) reacted to certain types of stimulation by firing electrical signals, which indicates they are active and capable of influencing neighboring neurons. Additionally, when the concentration of salt in their surroundings increased, the neurons became more excited, suggesting that they play a role in responding to changes in body fluids.
Who this helps: This research benefits scientists studying brain functions related to hydration and hormones.
Norepinephrine injections in diagonal band of Broca selectively reduced the activity of vasopressin supraoptic neurons in the rat.
1993
Brain research
Cunningham JT, Nissen R, Renaud LP
Plain English This study looked at how norepinephrine injections into a specific area of the brain called the diagonal band of Broca affect neurons that produce vasopressin, a hormone important for regulating blood pressure. Researchers found that these injections stopped the activity of 80% of vasopressin-secreting neurons, while only 7% of oxytocin-secreting neurons showed a similar drop in activity. This matters because it helps us understand how the brain regulates hormones linked to blood pressure, which could have implications for treating conditions related to blood pressure regulation.
Who this helps: This information benefits doctors and researchers working on treatments for blood pressure-related disorders.
Electrophysiology of central pathways controlling release of neurohypophysial hormones. Focus on the lamina terminalis and diagonal band inputs to the supraoptic nucleus.
Lateral hypothalamic lesions alter baroreceptor-evoked inhibition of rat supraoptic vasopressin neurones.
1993
The Journal of physiology
Nissen R, Cunningham JT, Renaud LP
Plain English This study looked at how damage to a specific part of the brain (the lateral hypothalamus) affects the way certain neurons respond when blood pressure changes. Researchers found that in normal rats, most neurons (34 out of 39) reacted to increased blood pressure, but in rats with damage to the lateral hypothalamus, only 12 out of 34 neurons showed the same response. This matters because it helps us understand how the brain regulates important hormones like vasopressin, which can influence blood pressure and fluid balance in the body.
Who this helps: This helps doctors and researchers looking to improve treatments for conditions related to blood pressure and hormone regulation.
Rat supraoptic neurons are resistant to glutamate neurotoxicity.
1992
Neuroreport
Hu B, Cunningham JT, Nissen R, Renaud LP, Bourque CW
Plain English This study examined how rat neurons in a specific brain region, the supraoptic nucleus (SON), respond to glutamate toxicity. Researchers found that even when surrounding cells were damaged, the SON neurons remained unharmed and continued to function normally, showing no significant differences in their activity compared to healthy cells. This discovery is important because it reveals that these neurons have a natural resistance to glutamate's harmful effects, which could play a crucial role in understanding brain health and developing therapies for neurodegenerative diseases.
Who this helps: This helps patients with neurodegenerative diseases and their doctors.
Ibotenate lesions of the diagonal band of broca attenuate baroreceptor sensitivity of rat supraoptic vasopressin neurons.
1992
Journal of neuroendocrinology
Cunningham JT, Nissen R, Renaud LP
Plain English This study looked at how certain brain cells in rats affect the body's response to changes in blood pressure. Researchers found that when they damaged a specific area of the brain called the diagonal band of Broca, fewer vasopressin-secreting neurons responded to increases in blood pressure—only 8 out of 21 neurons tested were affected, compared to 19 out of 21 in normal rats. This matters because it helps us understand how the brain regulates important functions like blood pressure and fluid balance, which can influence treatments for various medical conditions.
Who this helps: This helps patients with blood pressure issues and their doctors.
Catecholamine depletion of the diagonal band reduces baroreflex inhibition of supraoptic neurons.
1992
The American journal of physiology
Cunningham JT, Nissen R, Renaud LP
Plain English This study looked at how certain brain cells in rats respond to changes in blood pressure and how the loss of a specific chemical, catecholamine, affects that response. Researchers found that when they depleted catecholamine in a part of the brain called the diagonal band of Broca, only 37% of the vasopressin neurons, which help control blood pressure, were affected by increased blood pressure, compared to 100% in normal conditions. This matters because it helps us understand how brain signals interact with blood pressure regulation, which could inform treatments for conditions related to blood pressure control.
Who this helps: This helps patients with blood pressure disorders and their doctors.
[Post-traumatic edema as a limiting factor in early functional treatment measures and its pharmacodynamic modification].
1989
Langenbecks Archiv fur Chirurgie. Supplement II, Verhandlungen der Deutschen Gesellschaft fur Chirurgie. Deutsche Gesellschaft fur Chirurgie. Kongress
Nissen R, Loeschke S, Peters A
Plain English This study examined the problem of swelling, known as post-traumatic edema, that happens after fractures and makes it hard for patients to start exercising again. Researchers found that using certain medications, specifically cyclooxygenase inhibitors like azapropazone, reduced swelling by 30% after bimalleolar fractures. This is important because less swelling can lead to better recovery and quicker return to movement for those with fractures.
Who this helps: Patients recovering from fractures.
Release of atrial natriuretic factor from intact and hypophysectomized rat hypothalamic expiants.
1989
Journal of neuroendocrinology
Nissen R, Gutkowska J, Renaud LP
Plain English Researchers studied how a substance called atrial natriuretic factor (ANF) is released from the hypothalamus of rats. They found that the release of ANF increased from 6.1 to 11.4 picograms per sample after infusing noradrenaline, a chemical that stimulates the body’s response to stress. Interestingly, while the release levels from normal rat hypothalamus and those with a specific gland removed were similar, the response to noradrenaline was absent in the latter, indicating that certain brain areas play a role in this process.
Who this helps: This research helps scientists better understand how the brain regulates substances that affect blood pressure and fluid balance, which can benefit patients with heart and kidney conditions.
Increased turnover of arterial collagen in hypertensive rats.
1978
Proceedings of the National Academy of Sciences of the United States of America
Nissen R, Cardinale GJ, Udenfriend S
Plain English This study looked at how quickly collagen, a key protein that gives structure to our tissues, breaks down and is replaced in normal and high blood pressure (hypertensive) rats. The researchers found that in rats with high blood pressure, collagen in the aorta and mesenteric artery broke down much faster, with a half-life of only 17 days compared to 60-70 days in normal rats. This difference suggests that high blood pressure may lead to quicker changes in blood vessel structure, which can affect heart health.
Who this helps: This information benefits doctors and researchers studying heart disease and hypertension.
[Peptidyl prolyl hydroxylase activity in relation to the actual collagen biosynthesis in cotton pellet granuloma of guinea pig (author's transl)].
1977
Research in experimental medicine. Zeitschrift fur die gesamte experimentelle Medizin einschliesslich experimenteller Chirurgie
Langness U, Nissen R
Plain English This study examined how a specific enzyme, peptidyl prolyl hydroxylase, is involved in the creation of collagen during the formation of granulomas (tumor-like structures) in guinea pigs. The researchers found a strong link between the activity of this enzyme and the amount of collagen produced, indicating that this enzymatic process may be a crucial step in collagen formation. This information is important because understanding collagen synthesis can help improve treatments for conditions involving tissue repair and scarring.
Who this helps: This helps patients who are dealing with healing from injuries or conditions that affect tissue regeneration.
[20 years in the management of reflux disease using fundoplication].
1977
Der Chirurg; Zeitschrift fur alle Gebiete der operativen Medizen
Nissen R, Rossetti M, Siewert R
Plain English Over the past 20 years, a surgical procedure called fundoplication has become the most commonly used surgery for treating reflux disease because it effectively prevents reflux symptoms. However, some patients experienced complications due to improper diagnosis or technique. To improve outcomes, it's important for doctors to only recommend this surgery when reflux disease is clearly diagnosed.
Who this helps: This research benefits patients suffering from severe reflux disease and doctors who perform this surgery.