Browsing by Subject "Temperature"
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Item ASSOCIATION BETWEEN PLANTAR TEMPERATURE INCREASE AND PLANTAR SHEAR STRESSES IN HEALTHY SUBJECTS(2014-03) Brem, Ryan; Bawa, Binky; Master, Hiral; Flyzik, Michael; Yavuz, MetinUnnoticed repetitive plantar stresses are believed to cause diabetic foot ulcers. In severe cases, the development of these foot ulcers can lead to lower extremity amputations. The measurement of vertical plantar pressure has previously been used to predict where ulcers may develop, but was eventually determined to be a poor predictor of these occurrences. Shear is an additional element of plantar stresses that has not been thoroughly investigated due to the lack of available stress platforms with the capability of measuring the horizontal component stresses. Previous investigations have implemented the use of plantar temperature profiles in an attempt to develop an alternative method for determining plantar loading. Increases in temperature were seen and may have been a result of friction from plantar shear forces according to these reports. However, the potential relationship between temperature and shear has not been investigated thoroughly. If significant associations can be determined between the location and magnitude of both peak shear and temperature, researchers and clinicians may develop a better understanding of diabetic foot ulcer formation which could potentially lead to improvements in therapeutic footwear. Purpose (a): Sites of increased plantar temperature have been suggested to indicate plantar loading in previous investigations. However, this idea has not been successfully validated. The purpose of this study was to determine if a linear relationship existed between walking-induced increases in plantar temperature and measured plantar stresses. Significant relationships between the two variables would suggest thermographs to be an effective tool used to assess plantar tri-axial and/or shear loading, potentially leading to significant advancements in the study of biomechanical factors related to the diabetic amputations. Methods (b): Thirteen healthy participants were recruited, and informed consent was obtained prior to the study. Pre-exercise baseline plantar temperature profiles were measured with the use of an infrared thermal camera. Participants were then asked to walk on a custom-built platform that was used to measure tri-axial plantar stress distributions. Subjects then walked barefoot on a treadmill for 10 minutes. Post-exercise temperature distribution was measured and recorded. After all data were collected, sites of increased peak temperature and peak stress for each foot were documented. The frequency in which the two different sites matched was determined. In addition, increased peak temperature values were correlated against plantar stress magnitudes. Results (c): Peak temperature increase site matched the location of peak shear in 23% of participants. Peak temperature increase site also occurred at the peak resultant stress site in 39% of participants. A significant correlation was found between the magnitudes of temperature increase and peak shear (R = 0.78, p = 0.02). Conclusions (d): A moderate linear relationship was established between peak plantar temperature increase and the horizontal component of plantar stresses. It may be useful to explore a potential non-linear association between these two variables. If a non-linear relationship can be modeled, predicting plantar shear may be possible. The ability to predict plantar shear could allow for assistance in assessing the risk of ulcer development in the diabetic foot and subsequent amputation. Thermographs are still not a reliable source for the prediction of shear, but our initial results warrant further investigation.Item CLINICAL VALUE OF TEMPERATURE IN ASSESSING FOOT LOADING IN DIABETIC PATIENTS WITH AND WITHOUT NEUROPATHY(2014-03) Master, Hiral; Brem, Ryan; Bawa, Binky; Flyzik, Michael; Yavuz, MetinUnnoticed repetitive plantar stresses are believed to cause diabetic foot ulcers. In severe cases, the development of these foot ulcers can lead to lower extremity amputations. The measurement of vertical plantar pressure has previously been used to predict where ulcers may develop, but was eventually determined to be a poor predictor of these occurrences. Shear is an additional element of plantar stresses that has not been thoroughly investigated due to the lack of available stress platforms with the capability of measuring the horizontal component stresses. In a limited number of studies higher shear stresses have been found in diabetic patients. Previous investigations have implemented the use of plantar temperature profiles in an attempt to develop an alternative method for determining plantar loading. Increases in temperature were seen and may have been a result of friction from plantar shear forces according to these reports. However, the potential relationship between temperature and shear has not been investigated thoroughly. If significant associations can be determined between the location and magnitude of both peak shear and temperature, researchers and clinicians may develop a better understanding of diabetic foot ulcer formation which could potentially lead to improvements in therapeutic footwear. Purpose (a): Diabetic ulcers lead to an estimated 100,000 amputations every year in the United States. Ulcers are known to have a biomechanical etiology that relates to three dimensional ground reaction forces/stresses. Among these stresses, horizontal shear stress cannot be easily quantified. It was hypothesized that plantar temperatures can estimate shear loading of the foot. The purpose of this study was to explore a site-wise association between peak plantar temperature and peak pressure and shear stresses obtained from diabetic patients using a thermal camera and custom-built pressure-shear plate. If confirmed, thermographs can assist clinicians/researchers in preventing diabetic ulcer related amputations. Methods (b): Two groups, each consisting of 14 diabetic patients with neuropathy (DN) or without neuropathy (DC), were recruited for the study after informed consent was obtained. Resting foot sole temperatures were recorded using an infrared thermal camera. Subjects walked on a 12 ft. walkway that accommodated the stress plate. Stress variables such as peak pressure (PP), peak shear (PS), peak pressure integral time (PTI) and peak shear-time integral (STI) were recorded from five regions of the foot (i.e., hallux, lesser toes, first metatarsal head (1st MTH), central forefoot (2nd and 3rd MTH) and lateral forefoot (4th and 5th MTH)). Results (c): Pearson correlation analysis between each stress variable against temperature were statistically significant (p<0.05) in both groups. The r values ranged between .405 and .511. Despite significant correlation results, peak temperatures could not successfully identify peak stress locations in group DN (14-57%). Success rates were higher for the DC group (50-86%). Conclusions (d): The potential association between plantar stresses and temperature is thought to have a complicated and non-linear relationship. Appropriate modeling schemes can be implemented to explore such relationships. Thus our results warrant further investigation on this topic.Item Effects of temperature on bacterial microbiome composition in Ixodes scapularis ticks(John Wiley & Sons, Inc., 2018-09-21) Thapa, Santosh; Zhang, Yan; Allen, Michael S.Ixodes scapularis, the blacklegged deer tick, is the principal vector of Lyme disease in North America. Environmental factors are known to influence regional and seasonal incidence of Lyme disease and possibly the endemicity of the disease to the northeastern and upper mid-western regions of the United States. With a goal to understand the impact of environmental temperature on microbial communities within the tick, we investigated the bacterial microbiome of colony-reared I. scapularis ticks statically incubated at different temperatures (4, 20, 30, and 37°C) at a constant humidity in a controlled laboratory setting by comparison of sequenced amplicons of the bacterial 16S V4 rRNA gene to that of the untreated baseline controls. The microbiomes of colony-reared I. scapularis males were distinct than that of females, which were entirely dominated by Rickettsia. In silico removal of Rickettsia sequences from female data revealed the underlying bacterial community, which is consistent in complexity with those seen among male ticks. The bacterial community composition of these ticks changes upon incubation at 30°C for a week and 37°C for more than 5 days. Moreover, the male ticks incubated at 30 and 37°C exhibited significantly different bacterial diversity compared to the initial baseline microbiome, and the change in bacterial diversity was dependent upon duration of exposure. Rickettsia-free data revealed a significantly different bacterial diversity in female ticks incubated at 37°C compared to that of 4 and 20°C treatments. These results provide experimental evidence that environmental temperature can impact the tick bacterial microbiome in a laboratory setting.Item Genetically engineered probiotic for the treatment of phenylketonuria (PKU); assessment of a novel treatment in vitro and in the PAHenu2 mouse model of PKU(PLOS, 2017-05-17) Durrer, Katherine E.; Allen, Michael S.; Hunt von Herbing, IonePhenylketonuria (PKU) is a genetic disease characterized by the inability to convert dietary phenylalanine to tyrosine by phenylalanine hydroxylase. Given the importance of gut microbes in digestion, a genetically engineered microbe could potentially degrade some ingested phenylalanine from the diet prior to absorption. To test this, a phenylalanine lyase gene from Anabaena variabilis (AvPAL) was codon-optimized and cloned into a shuttle vector for expression in Lactobacillus reuteri 100-23C (pHENOMMenal). Functional expression of AvPAL was determined in vitro, and subsequently tested in vivo in homozygous PAHenu2 (PKU model) mice. Initial trials of two PAHenu2 homozygous (PKU) mice defined conditions for freeze-drying and delivery of bacteria. Animals showed reduced blood phe within three to four days of treatment with pHENOMMenal probiotic, and blood phe concentrations remained significantly reduced (P < 0.0005) compared to untreated controls during the course of experiments. Although pHENOMMenal probiotic could be cultured from fecal samples at four months post treatment, it could no longer be cultivated from feces at eight months post treatment, indicating eventual loss of the microbe from the gut. Preliminary screens during experimentation found no immune response to AvPAL. Collectively these studies provide data for the use of a genetically engineered probiotic as a potential treatment for PKU.Item Spatial and temporal patterns of dengue incidence in northeastern Thailand 2006-2016(BioMed Central Ltd., 2019-08-23) Phanitchat, Thipruethai; Zhao, Bingxin; Haque, Ubydul; Pientong, Chamsai; Ekalaksananan, Tipaya; Aromseree, Sirinart; Thaewnongiew, Kesorn; Fustec, Benedicte; Bangs, Michael J.; Alexander, Neal; Overgaard, Hans J.BACKGROUND: Dengue, a viral disease transmitted by Aedes mosquitoes, is an important public health concern throughout Thailand. Climate variables are potential predictors of dengue transmission. Associations between climate variables and dengue have usually been performed on large-scale first-level national administrative divisions, i.e. provinces. Here we analyze data on a finer spatial resolution in one province, which is often more relevant for effective disease control design. The objective of this study was to investigate the effect of seasonal variations, monthly climate variability, and to identify local clusters of symptomatic disease at the sub-district level based on reported dengue cases. METHODS: Data on dengue cases were retrieved from the national communicable disease surveillance system in Thailand. Between 2006 and 2016, 15,167 cases were recorded in 199 sub-districts of Khon Kaen Province, northeastern Thailand. Descriptive analyses included demographic characteristics and temporal patterns of disease and climate variables. The association between monthly disease incidence and climate variations was analyzed at the sub-district level using Bayesian Poisson spatial regression. A hotspot analysis was used to assess the spatial patterns (clustered/dispersed/random) of dengue incidence. RESULTS: Dengue was predominant in the 5-14 year-old age group (51.1%). However, over time, dengue incidence in the older age groups (> 15 years) gradually increased and was the most affected group in 2013. Dengue outbreaks coincide with the rainy season. In the spatial regression model, maximum temperature was associated with higher incidence. The hotspot analysis showed clustering of cases around the urbanized area of Khon Kaen city and in rural areas in the southwestern portion of the province. CONCLUSIONS: There was an increase in the number of reported dengue cases in older age groups over the study period. Dengue incidence was highly seasonal and positively associated with maximum ambient temperature. However, climatic variables did not explain all the spatial variation of dengue in the province. Further analyses are needed to clarify the detailed effects of urbanization and other potential environmental risk factors. These results provide useful information for ongoing prediction modeling and developing of dengue early warning systems to guide vector control operations.