Unique Physiological Response Research Articles

Four-session treatment for specific phobias: Memory regression as a therapeutic tool for blood phobia

This study addresses the effectiveness of memory regression as a therapeutic method for individuals with blood-injection-injury (BII) phobia, a condition that manifests itself through extreme fear and avoidance of seeing blood, receiving injections, or being present in invasive medical situations. Differentiated from other phobias by its unique physiological response, including fainting, and the feeling of disgust, BII significantly impacts patients' lives, limiting access to essential medical care and influencing professional and lifestyle choices. The prevalence of this phobia ranges from 0.8 to 1.5% among children and adolescents, reaching 3 to 4.5% in adults, but its therapeutic approach is often neglected in the specialized literature. This article explores memory regression as a promising intervention, suggesting that by revisiting and reinterpreting the past traumatic experiences that underlie the phobia, patients can achieve a deeper understanding and resolution of their fears. Preliminary results indicate a significant reduction in anxiety and phobic avoidance, demonstrating the potential of memory regression as a valuable tool in the therapeutic arsenal for the treatment of IBD. This study contributes to the field of psychotherapy by providing insights into the applicability and efficacy of memory regression, emphasizing the importance of innovative approaches in the treatment of specific phobias.

From data to decision: Machine learning determination of aerobic and anaerobic thresholds in athletes.

Lactate analysis plays an important role in sports science and training decisions for optimising performance, endurance, and overall success in sports. Two parameters are widely used for these goals: aerobic (AeT) and anaerobic (AnT) thresholds. However, determining AeT proves more challenging than AnT threshold due to both physiological intricacies and practical considerations. Thus, the aim of this study was to determine AeT and AnT thresholds using machine learning modelling (ML) and to compare ML-obtained results with the parameters' values determined using conventional methods. ML seems to be highly useful due to its ability to handle complex, personalised data, identify nonlinear relationships, and provide accurate predictions. The 183 results of CardioPulmonary Exercise Test (CPET) accompanied by lactate and heart ratio analyses from amateur athletes were enrolled to the study and ML models using the following algorithms: Random Forest, XGBoost (Extreme Gradient Boosting), and LightGBM (Light Gradient Boosting Machine) and metrics: R2, mean absolute error (MAE), mean squared error (MSE) and root mean square error (RMSE). The regressors used belong to the group of ensemble learning algorithms that combine the predictions of multiple base models to improve overall performance and counteract overfitting to training data. Based on evaluation metrics, the following models give the best predictions: for AeT: Random Forest has an R2 value of 0.645, MAE of 4.630, MSE of 44.450, RMSE of 6.667; and for AnT: LightGBM has an R2 of 0.803, the highest among the models, MAE of 3.439, the lowest among the models, MSE of 20.953, and RMSE of 4.577. Outlined research experiments, a comprehensive review of existing literature in the field, and obtained results suggest that ML models can be trained to make personalised predictions based on an individual athlete's unique physiological response to exercise. Athletes exhibit significant variation in their AeT and AT, and ML can capture these individual differences, allowing for tailored training recommendations and performance optimization.

FRI175 Presentation, Etiology And Outcomes Of Adrenal Hemorrhage A Large Single-center Study

Abstract Disclosure: M. Chinthapalli: None. P. Dogra: None. R. Sandooja: None. L. Rahimi: None. N.M. Iniguez Ariza: None. T. Foster: None. I. Bancos: None. Introduction: Adrenal glands are susceptible to hemorrhage due to their unique vasculature and physiological stress response. Scarce data are available on the presentation, etiology, and outcomes of adrenal hemorrhage (AH). Objective: To describe the presentation, etiological associations, and outcomes of patients with unilateral and bilateral AH. Methods: Single-center retrospective longitudinal study of consecutive patients reported to have AH on imaging performed between January 1st 2017-December 31st 2021. Clinical, baseline and follow up imaging, and laboratory data were reviewed. Subgroup analysis was performed based on the laterality (unilateral vs. bilateral) of AH. Results: Of 454 patients with AH (median age 62 years (IQR 50-70), 160 (35%) women), 383 (85%) had unilateral AH, 60 (13%) presented with synchronous bilateral AH, and 9 (2%) had unilateral AH followed by contralateral AH at a later time (metachronous bilateral AH). Only 93 (20%) patients had an evaluation by an endocrinologist. AH was discovered incidentally in 190 (42%) patients, and during evaluation for abdominal or back pain in 133 (29%), trauma in 104 (23%), sepsis in 19 (4%), and adrenal insufficiency in 8 (2%). Primary etiology of AH was a post-procedural complication in 154 (34%), trauma in 126 (28%), coagulopathy in 54 (12%), anticoagulant or antiplatelet therapy in 52 (12%), adrenal neoplasm in 29 (6%) and sepsis in 20 (4%). Metastasis (15, 50%) represented the most common adrenal neoplasm associated with AH. In 208 (46%) patients, diagnosis of AH occurred in the hospital setting, and in 246 (54%) during an outpatient evaluation. In the 393 patients with available baseline imaging, the median size of AH was 3.1 cm (IQR 2.2-4.0). During a median imaging follow-up of 6 months (IQR 3-12), AH reduced in size with a median decrease of -2.6 cm (IQR -1.8 to -3.7) on the right and -2.0 cm (IQR -1.0 to -4.8) on the left. Compared to patients with unilateral AH, those with bilateral AH were more likely to be diagnosed in the hospital setting (61 vs. 43%, P=0.006), have an underlying coagulopathy (50 vs. 4%, P<0.0001), or sepsis (13 vs. 3%, P<0.0001), be on anticoagulant or antiplatelet therapy (48 vs. 21%, P<0.0001), develop primary adrenal insufficiency (61 vs. 0%, P<0.0001) and have larger baseline AH size (4 cm vs. left 2.7 and right 3.1 cm, P=0.0002), but a similar rate of resolution. Conclusions: AH frequently presents as unilateral hemorrhage and can occur secondary to various etiologies, with trauma and postprocedural complication being the most common. Association with an underlying adrenal mass is uncommon, seen only in 6%. Bilateral AH carries a high risk for primary adrenal insufficiency and is more likely to occur in hospitalized patients, possibly due to an increased prevalence of underlying coagulopathy, sepsis and need for anticoagulation or antiplatelet therapy. Presentation: Friday, June 16, 2023

The influence of asymmetrical bipolar pulses and interphase intervals on the bipolar cancellation phenomenon in the ovarian cancer cell line

The application of negative polarity electrical pulse (↓) following positive polarity pulses (↑) may induce bipolar cancellation (BPC), a unique physiological response believed to be specific to nanosecond electroporation (nsEP). The literature lacks analysis of bipolar electroporation (BP EP) involving asymmetrical sequences composed of nanosecond and microsecond pulses. Moreover, the impact of interphase interval on BPC caused by such asymmetrical pulse needs consideration. In this study, the authors utilized the ovarian clear carcinoma cell line (OvBH-1) model to investigate the BPC with asymmetrical sequences. Cells were exposed to pulses delivered in 10-pulse bursts but as uni- or bipolar, symmetrical, or asymmetrical sequences with a duration of 600 ns or 10 µs and electric field strength equal to 7.0 or 1.8 kV/cm, respectively. It was shown that the asymmetry of pulses influences BPC. The obtained results have also been investigated in the context of calcium electrochemotherapy. The reduction of cell membrane poration, and cell survival have been observed following Ca2+ electrochemotherapy. The effects of interphase delays (1 and 10 µs) on the BPC phenomenon were reported. Our findings show that the BPC phenomenon can be controlled using pulse asymmetry or delay between the positive and negative polarity of the pulse.

Millimeter waves alter DNA secondary structures and modulate the transcriptome in human fibroblasts.

As millimetre wave (MMW) frequencies of the electromagnetic spectrum are increasingly adopted in modern technologies such as mobile communications and networking, characterising the biological effects is critical in determining safe exposure levels. We study the exposure of primary human dermal fibroblasts to MMWs, finding MMWs trigger genomic and transcriptomic alterations. In particular, repeated 60 GHz, 2.6 mW cm-2, 46.8 J cm-2 d-1 MMW doses induce a unique physiological response after 2 and 4 days exposure. We show that high dose MMWs induce simultaneous non-thermal alterations to the transcriptome and DNA structural dynamics, including formation of G-quadruplex and i-motif secondary structures, but not DNA damage.

ROLE OF HYPERCORTISOLEMIA IN PROGRESSION OF THE COMORBID COURSE OF CORONARY ARTERY DISEASE, DIABETES MELLITUS TYPE 2 AND ANEMIA

INTRODUCTION: Hyperactivation of stress-limiting mechanisms of the organism is a unique physiological response of the human being to chronic hypoxia of different origins.
 OBJECTIVES: Investigation of dynamics of cortisol synthesis changes in patients with coronary artery disease with comorbid diabetes mellitus type 2 and anemic syndrome in patients of older age groups.
 METHODS: Blood cortisol level was measured in 40 old and senile coronary artery disease patients with comorbid diabetes mellitus type 2 and anemic syndrome of different degrees of severity. The control group consisted of 12 patients with coronary artery disease without comorbidities that were not significantly different through gender and age from the patients of the research groups. Possible effects of telmisartan on the degree of chronic hypoxia were also investigated.
 RESULTS: In patients of old and senile age with coronary artery disease and comorbid anemic syndrome, same as in case of coronary artery disease and anemic syndrome on the background of diabetes mellitus type 2, activation of the cortisol synthesis is observed, likely in response to hypoxia as a stress factor in anemia. The degree of severity of the detected changes was different depending on the degree of anemia severity. There was no normalization of cortisol content in blood in any of the major experimental groups regardless the prescribed treatment with ACE inhibitors or telmisartan.
 CONCLUSIONS: In patients with coronary artery disease, same as in the case of a comorbid course of coronary artery disease and diabetes mellitus type 2, an increase of cortisol secretion in response to anemic hypoxia was observed. As the degree of severity of the anemic syndrome progressed, gradual decreasing of cortisol blood level was detected. Reduction of the intensity of stress-limiting systems in the organism by telmisartan prescription may help to eliminate the adverse effects of hypercortisolemia on the progression of coronary artery disease, especially on the background of comorbid diabetes mellitus type 2 and anemia.

Invited review: Management strategies capable of improving the reproductive performance of heat-stressed dairy cattle

Impaired fertility during periods of heat stress is the culmination of numerous physiological responses to heat stress, ranging from reduced estrus expression and altered follicular function to early embryonic death. Furthermore, heat-stressed dairy cattle exhibit a unique metabolic status that likely contributes to the observed reduction in fertility. An understanding of this unique physiological response can be used as a basis for improving cow management strategies, thereby reducing the negative effects of heat stress on reproduction. Potential opportunities for improving the management of dairy cattle during heat stress vary greatly and include feed additives, targeted cooling, genetic selection, embryo transfer and, potentially, crossbreeding. Previous studies indicate that dietary interventions such as melatonin and chromium supplementation could alleviate some of the detrimental effects of heat stress on fertility, and that factors involved in the methionine cycle would likely do the same. These supplements, particularly chromium, may improve reproductive performance during heat stress by alleviating insulin-mediated damage to the follicle and its enclosed cumulus-oocyte complex. Beyond feed additives, some of the simplest, yet most effective strategies involve altering the timing of feeding and cooling to take advantage of comparatively low nighttime temperatures. Likewise, expansion of cooling systems to include breeding-age heifers and dry cows has significant benefits for dams and their offspring. More complicated but promising strategies involve the calculation of breeding values for thermotolerance, the identification of genomic markers for heat tolerance, and the development of bedding-based conductive cooling systems. Unfortunately, no single approach can completely rescue the fertility of lactating dairy cows during heat stress. That said, region-appropriate combinations of strategies can improve reproductive measures to reasonable levels.

Fired Up by Morality: The Unique Physiological Response Tied to Moral Conviction in Politics

Studies provide mounting evidence that morally convicted attitudes elicit passionate and unyielding political responses. Questions remain, however, whether these effects occur because moral conviction is another strong, versus a distinctly moral dimension of attitude strength. Building on work in moral psychology and neuroscience, I argue that moral conviction stems from a distinctive mode of mental processing that is tied to automatic affective reactions. Testing this idea using a lab experiment designed to capture self‐reported moral conviction and physiological arousal, I find that conviction about political objects positively predicts arousal evoked by the objects, while attitude extremity and importance do not. These findings suggest that moral conviction items do tap into moral processing, helping to validate the conviction measure. They also illustrate the value of using physiological indicators to study politics, help explain why morally convicted attitudes trigger such fervent responses, and raise normative questions about political conflict and compromise.

Common bean varieties demonstrate differential physiological and metabolic responses to the pathogenic fungus Sclerotinia sclerotiorum.

Plant physiology and metabolism are important components of a plant response to microbial pathogens. Physiological resistance of common bean (Phaseolus vulgaris L.) to the fungal pathogen Sclerotinia sclerotiorum has been established, but the mechanisms of resistance are largely unknown. Here, the physiological and metabolic responses of bean varieties that differ in physiological resistance to S.sclerotiorum are investigated. Upon infection, the resistant bean variety A195 had a unique physiological response that included reduced photosynthesis and maintaining a higher leaf surface pH during infection. Leaf metabolomics was performed on healthy tissue adjacent to the necrotic lesion at 16, 24, and 48hr post inoculation, and 144 metabolites were detected that varied between A195 and Sacramento following infection. The metabolites that varied in leaves included amines/amino acids, organic acids, phytoalexins, and ureides. The metabolic pathways associated with resistance included amine metabolism, uriede-based nitrogen remobilization, antioxidant production, and bean-specific phytoalexin production. A second experiment was conducted in stems of 13 bean genotypes with varying resistance. Stem resistance was associated with phytoalexin production, but unlike leaf metabolism, lipid changes were associated with susceptibility. Taken together, the data supports a multifaceted, physiometabolic response of common bean to S.sclerotiorum that mediates resistance.

Rebuttal from Scott K. Powers, Ashley J. Smuder, David Fuller and Sanford Levine

Drs Sieck and Mantilla have presented an eloquent argument that diaphragm muscle fibre atrophy following unilateral phrenicotomy, tetrodotoxin (TTX) nerve blockade or high cervical spinal hemisection injury does not result from muscle inactivity alone. Nonetheless, we retain our position that when diaphragmatic contractile work is diminished during prolonged mechanical ventilation (MV), the ensuing diaphragm fibre atrophy occurs primarily due to decreased diaphragm contractile activity. In our response to Dr Sieck and Mantilla's position, we highlight several fundamental differences between the unilateral denervation model of diaphragm inactivity and the reduced diaphragmatic contractile work that occurs during prolonged MV. A fundamental difference between these two models of diaphragm inactivity is that prolonged MV results in atrophy of all diaphragm muscle fibre types whereas unilateral phrenic denervation promotes a transient hypertrophy of diaphragmatic type I and IIa fibres followed by atrophy of type IIx and IIb fibres. This is a unique physiological response as muscle hypertrophy does not occur in any other model of skeletal muscle inactivity. Another major difference is that diaphragm movement patterns differ markedly between the unilateral phrenic denervation model of diaphragm inactivity and MV. During MV, both hemidiaphragms move synchronously as the lungs inflate and empty. In contrast, following unilateral phrenic denervation, the contralateral hemidiaphragm contracts and shortens, thus eliciting small fibre length changes in the paralysed hemidiaphragm (Zhan et al. 1995). Since muscle fibre size is a highly regulated process controlled by mechanical signals, neurotrophic influences, and paracrine signalling which regulate muscle protein turnover (Rennie et al. 2004), the possibility exists that distortion of the paralysed diaphragm elicits an anabolic signalling response to promote hypertrophy. Importantly, not all studies report diaphragmatic hypertrophy following denervation-induced inactivity. Indeed, a study from Dr Sieck's laboratory revealed that unilateral denervation of the rat diaphragm results in a net loss of muscle protein after 5 days (Argadine et al. 2009). It follows that this deficit of muscle protein should translate into diaphragm fibre atrophy but unfortunately, this study did not report diaphragm fibre size. Further, in direct contrast to the rat data, hemidiaphragm paralysis in humans results in atrophy of diaphragm slow muscle fibres with atrophy of fast fibres occurring at a slower time course (Welvaart et al. 2011). Interestingly, these results agree with the Sieck–Mantilla initial theoretical argument that inactivity-induced diaphragm muscle fibre atrophy should occur most rapidly in slow fibres. In conclusion, based on our work and the work of others, we maintain the position that during prolonged MV, when diaphragm work against external loads is greatly diminished, the ensuing diaphragm atrophy is primarily due to decreased diaphragm contractile work.

Major channels involved in neuropsychiatric disorders and therapeutic perspectives

Voltage-gated ion channels are important mediators of physiological functions in the central nervous system. The cyclic activation of these channels influences neurotransmitter release, neuron excitability, gene transcription, and plasticity, providing distinct brain areas with unique physiological and pharmacological response. A growing body of data has implicated ion channels in the susceptibility or pathogenesis of psychiatric diseases. Indeed, population studies support the association of polymorphisms in calcium and potassium channels with the genetic risk for bipolar disorders (BPDs) or schizophrenia. Moreover, point mutations in calcium, sodium, and potassium channel genes have been identified in some childhood developmental disorders. Finally, antibodies against potassium channel complexes occur in a series of autoimmune psychiatric diseases. Here we report recent studies assessing the role of calcium, sodium, and potassium channels in BPD, schizophrenia, and autism spectrum disorders, and briefly summarize promising pharmacological strategies targeted on ion channels for the therapy of mental illness and related genetic tests.

Fructose consumption during pregnancy and lactation induces fatty liver and glucose intolerance in rats

Nutritional insults during pregnancy and lactation are health risks for mother and offspring. Both fructose (FR) and low-protein (LP) diets are linked to hepatic steatosis and insulin resistance in nonpregnant animals. We hypothesized that dietary FR or LP intake during pregnancy may exacerbate the already compromised glucose homeostasis to induce gestational diabetes and fatty liver. Therefore, we investigated and compared the effects of LP or FR intake on hepatic steatosis and insulin resistance in unmated controls (CTs) and pregnant and lactating rats. Sprague-Dawley rats were fed a CT, or a 63% FR, or an 8% LP diet. Glucose tolerance test at day 17 of the study revealed greater (P < .05) blood glucose at 10 (75.6 mg/dL vs 64.0 ± 4.8 mg/dL) minutes and 20 (72.4 mg/dL vs 58.6 ± 4.0 mg/dL) minutes after glucose dose and greater area under the curve (4302.3 mg∙dL(-1)∙min(-1) vs 3763.4 ± 263.6 mg∙dL(-1)∙min(-1)) for FR-fed dams compared with CT-fed dams. The rats were euthanized at 21 days postpartum. Both the FR- and LP-fed dams had enlarged (P < .05) livers (9.3%, 7.1% body weight vs 4.8% ± 0.2% body weight) and elevated (P < .05) liver triacylglycerol (216.0, 130.0 mg/g vs 19.9 ± 12.6 mg/g liver weight) compared with CT-fed dams. Fructose induced fatty liver and glucose intolerance in pregnant and lactating rats, but not unmated CT rats. The data demonstrate a unique physiological status response to diet resulting in the development of gestational diabetes coupled with hepatic steatosis in FR-fed dams, which is more severe than an LP diet.

Root attributes affecting water uptake of rice (Oryza sativa) under drought

Lowland rice roots have a unique physiological response to drought because of their adaptation to flooded soil. Rice root attributes that facilitate growth under flooded conditions may affect rice response to drought, but the relative roles of root structural and functional characteristics for water uptake under drought in rice are not known. Morphological, anatomical, biochemical, and molecular attributes of soil-grown rice roots were measured to investigate the genotypic variability and genotype×environment interactions of water uptake under variable soil water regimes. Drought-resistant genotypes had the lowest night-time bleeding rates of sap from the root system in the field. Diurnal fluctuation predominated as the strongest source of variation for bleeding rates in the field and root hydraulic conductivity (Lp r) in the greenhouse, and was related to expression trends of various PIP and TIP aquaporins. Root anatomy was generally more responsive to drought treatments in drought-resistant genotypes. Suberization and compaction of sclerenchyma layer cells decreased under drought, whereas suberization of the endodermis increased, suggesting differential roles of these two cell layers for the retention of oxygen under flooded conditions (sclerenchyma layer) and retention of water under drought (endodermis). The results of this study point to the genetic variability in responsiveness to drought of rice roots in terms of morphology, anatomy, and function.

WATER USE RESPONSES OF SHIRAZ VINES UNDER PARTIAL ROOT ZONE DRYING IN A WATER-LIMITING ENVIRONMENT

The response of vines to deficit irrigation can be strongly influenced by variety, environmental and management factors such as climate, soil type, irrigation frequency, and amount of water applied. In the 2003/2004 season water was applied at two levels (0.9 and 0.45 ETc) either as partial root-zone drying (PRD) or as conventional drip irrigation (CI) to field-grown Shiraz vines in north-eastern Victoria, Australia. Application of PRD to vines resulted in a unique physiological response distinct from conventional irrigation, with PRD reducing water loss from the canopy under conditions of high evaporative demand. When water availability was not limited (i.e. shortly after irrigation events) PRD vines tightly regulated water loss from the canopy at high and low vapour pressure deficit (VPD). Measurements of stomatal conductance throughout the season suggest that for most of the experiment all vines experienced some degree of water stress. Limited water availability, low to medium vigour vines, restricted root development and high evaporative demand were all factors in the vine's response to PRD. The amount of water applied was the dominant influence on vine yield and vegetative growth in these experiments but there was a clear distinction between PRD and CI in the way that vines responded to evaporative demand.

Exercise limitation in patients with Fontan circulation: a review

The aim of the current literature study was to perform a literature review of the factors contributing to exercise limitation and physiological response to exercise in patients with Fontan circulation. In patients with Fontan circulation, peak oxygen uptake ranged from about 14.4 to 32.3 ml/min/kg, and showed a slowed acceleration in the kinetics of oxygen uptake at the onset of exercise. Peak heart rate during exercise was decreased to an average of 153 +/- 10 bpm and arterial oxygen saturation was also decreased at peak exercise, with an average of 89.5 +/- 1.94%. Cardiac output was subnormal, owing to reduced stroke volume, heart rate response and affected pulmonary venous return. Ventilatory anaerobic threshold was below normal values. Moreover, the ventilatory equivalent for carbon dioxide was found to be higher. Patients with Fontan circulation possess a unique physiological response to exercise. Although there is a wide range in exercise capacity among patients, all patients have reduced tolerance to exercise. Cardiac, pulmonary, and muscular factors might play a role in reduced exercise capacity and this distinct response to exercise.

Phytoextraction of Weathered p,p′-DDE by Zucchini (Cucurbita pepo) and Cucumber (Cucumis sativus) Under Different Cultivation Conditions

ABSTRACT Previous studies have shown that zucchini (Cucurbita pepo) and cucumber (Cucumis sativus) under field conditions are good and poor accumulators, respectively, of persistent organic pollutants from soil. Here, each species was grown under three cultivation regimes: dense (five plants in 5 kg soil); nondense (one plant in 80 kg soil); and field conditions (two to three plants in approximately 789 kg soil). p,p′-DDE and inorganic element content in roots, stems, leaves, and fruit were determined. In addition, rhizosphere, near-root, and unvegetated soil fractions were analyzed for concentrations of 11 low-molecular-weight organic acids (LMWOA) and 14 water-extractable inorganic elements. Under field conditions, zucchini phytoextracted 1.3% of the weathered p,p′-DDE with 98% of the contaminant in the aerial tissues. Conversely, cucumber removed 0.09% of the p,p′-DDE under field conditions with 83% in the aerial tissues. Under dense cultivation, cucumber produced a fine and fibrous root system not observed in our previous experiments and phytoextracted 0.78% of the contaminant, whereas zucchini removed only 0.59% under similar conditions. However, cucumber roots translocated only 5.7% of the pollutant to the shoot system, while in zucchini 48% of the p,p′-DDE in the plant was present in the aerial tissue. For each species, the concentrations of LMWOA in soil increased with increasing impact by the root system both within a given cultivation regime (i.e., rhizosphere > near-root > unvegetated) and across cultivation regimes (i.e., dense > nondense > field conditions). Under dense cultivation, the rhizosphere concentrations of LMWOAs were significantly greater for cucumber than for zucchini; no species differences were evident in the other two cultivation regimes. To enable direct comparison across cultivation regimes, total in planta p,p′-DDE and inorganic elements were mass normalized or multiplied by the ratio of plant mass to soil mass. For cucumber, differences in total p,p′-DDE and inorganic element content among the cultivation regimes largely disappear upon mass normalization, indicating that greater uptake of both types of constituents in the dense condition is due to greater plant biomass per unit soil. Conversely, for zucchini the mass normalized content of p,p′-DDE and inorganic elements is up to two orders of magnitude greater under field conditions than under dense cultivation, indicating a unique physiological response of C. pepo in the field. The role of cultivation conditions and nutrient availability in controlling root morphology, organic acid exudation, and contaminant uptake is discussed.

Metabolic differentiation in actively swarming Salmonella

Most current paradigms of microbial metabolism have been derived from studying cells grown under a variety of nutrient compositions in aqueous environments. With recent advances in genomics and experimental techniques, alternative forms of bacterial growth are increasingly being explored. When propagated on nutrient-rich semi-solid media, several species of bacteria undergo a morphological differentiation into swarmers that are capable of migrating on surfaces. Recent studies indicate that swarmer differentiation represents much more than a motility phenotype, as several clinically important attributes are also co-regulated. We demonstrate that migrating swarmer cells of Salmonella are metabolically differentiated compared to the vegetative swimmer cells grown in the same nutrient environment. Furthermore, once the cells have differentiated, the swarmers remain in this physiological state under conditions that do not promote the initial differentiation. The bacterium's capacity to override some of the classic paradigms of metabolic regulation established in aqueous environments represents a unique physiological response by the pathogen that may be advantageous in polymicrobial environments such as the host.

Tissue-Specific Gene Expression and Ecdysone-Regulated Genomic Networks in Drosophila

During insect metamorphosis, each tissue displays a unique physiological and morphological response to the steroid hormone 20-hydroxyecdysone (ecdysone). We assayed gene expression in five tissues during metamorphosis onset. Larval-specific tissues display major changes in genome-wide expression profiles, whereas tissues that survive into adulthood display few changes. In one larval tissue, the salivary gland, we used a computational approach to identify a regulatory motif and a cognate transcription factor involved in regulating a set of coexpressed genes. During the metamorphosis of another tissue, the midgut, genes encoding factors from the hedgehog, Notch, EGF, dpp, and wingless pathways are activated by the ecdysone regulatory network. Mutation of the ecdysone receptor abolishes their induction. Cell cycle genes are also activated during the initiation of midgut metamorphosis, and they are also dependent on ecdysone signaling. These results establish multiple new connections between the ecdysone regulatory network and other well-studied regulatory networks.

Applied physiology of diving.

Recreational diving is a popular sport, although human ability to stay in and under water is severely limited physiologically. An understanding of these limitations enhances safety and enjoyment of sports diving. Breath-hold diving involves head-out water immersion, apnoea and submersion, exercise, cold stress, and pressure exposure. Each of these components, by itself, elicits prominent and specific physiological effects. Combination of these factors produces a unique and interesting physiological response generally known as diving reflex. Humans display weak diving responses, but exhibit no oxygen conservation function. Nevertheless, application of diving-induced physiological changes is now finding its way into clinical practice. Apnoea, face immersion, and head-out water immersion all show promise of clinical application. There are several spin-offs from diving research worth noting. Diuresis, enhancement of cardiac performance, and redistribution of blood flow, all produced by head-out water immersion, have been shown to be clinically useful, besides providing physiological data useful to space travel. Results from investigations on apnoea have been shown to be relevant to the following: treating some forms of cardiac arrhythmias; understanding drowning, sudden infant death syndrome and sleep apnoea; and confirming hyperventilation as the major cause of drowning. In comparison to marine mammals, humans are poor divers because of severe physiological constraints which limit their breath-hold time, diving depth, and ability to conserve body heat. Although under special circumstances humans can achieve unusually long breath-hold time and reach exceptional depth with a single breath, the sustainable working time and depth are only about 1 minute and 5 metres, respectively. Hypothermia inevitably results in divers working in the ocean. Without thermal protection, the intolerable limit of 35 degrees C is reached within 30 minutes in winter (10 degrees C) water and within 60 to 90 minutes in summer. Nevertheless, effective harvest work can be performed by humans in the ocean, and recreational benefits enhanced when these physiological limitations are respected. An unusual circulatory state exists during head-out water immersion in that there is a sustained increase of stroke volume. This results in 30% increase in cardiac output when the subject is resting in thermal neutral water, indicating a substantial overperfusion for the oxygen requirement. Furthermore, animal experiments showed that the elevated blood flow is preferentially channeled to the liver, fat, and the organs in the splanchnic region.(ABSTRACT TRUNCATED AT 400 WORDS)