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PubMed2002

National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses.

OBJECTIVE: To present recommendations for the prevention, recognition, and treatment of exertional heat illnesses and to describe the relevant physiology of thermoregulation. BACKGROUND: Certified athletic trainers evaluate and treat heat-related injuries during athletic activity in "safe" and high-risk environments. While the recognition of heat illness has improved, the subtle signs and symptoms associated with heat illness are often overlooked, resulting in more serious problems for affected athletes. The recommendations presented here provide athletic trainers and allied health providers with an integrated scientific and practical approach to the prevention, recognition, and treatment of heat illnesses. These recommendations can be modified based on the environmental conditions of the site, the specific sport, and individual considerations to maximize safety and performance. RECOMMENDATIONS: Certified athletic trainers and other allied health providers should use these recommendations to establish on-site emergency plans for their venues and athletes. The primary goal of athlete safety is addressed through the prevention and recognition of heat-related illnesses and a well-developed plan to evaluate and treat affected athletes. Even with a heat-illness prevention plan that includes medical screening, acclimatization, conditioning, environmental monitoring, and suitable practice adjustments, heat illness can and does occur. Athletic trainers and other allied health providers must be prepared to respond in an expedient manner to alleviate symptoms and minimize morbidity and mortality.

Journal Article↗
PubMed1992

Vasoactive intestinal peptide and noradrenaline exert long-term control on glycogen levels in astrocytes: blockade by protein synthesis inhibition.

Vasoactive intestinal peptide (VIP) and noradrenaline (NA) have been previously shown to promote glycogenolysis in mouse cerebral cortex (Magistretti, 1990). This action, which is fully expressed within a few minutes, is exerted on astrocytes (Sorg and Magistretti, 1991). In the present article, we report a second, temporally delayed, action of VIP or NA in primary cultures of mouse cerebral cortical astrocytes; thus, following glycogenolysis, an induction of glycogen resynthesis is observed, resulting, within 9 hr, in glycogen levels that are 6-10 times higher than those measured before the application of either neurotransmitter. This effect of VIP or NA is concentration dependent and, for NA, is mediated by adrenergic receptors of the beta subtype. The continued presence of the neurotransmitter is not necessary for this long-term effect, since pulses as short as 1 min result in the doubling of glycogen levels 9 hr later. The induction of glycogen resynthesis triggered by VIP or NA is dependent on protein synthesis, since both cycloheximide and actinomycin D abolish it entirely. The ability to elicit glycogenolysis is not sufficient per se to trigger the induction of glycogen resynthesis. Thus, two glycogenolytic agents such as methoxamine, an alpha 1-adrenergic agonist, and phorbol 12,13-dibutyrate, both acting via protein kinase C activation, are unable to induce glycogen resynthesis. This observation, taken together with the fact that dibutyryl-cAMP application also results in enhanced glycogen resynthesis, strongly suggests that the long-term effect of VIP or NA is mediated by the cAMP second-messenger pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Evidence that endogenous somatostatin (SRIF) exerts a tonic inhibitory effect on the rat renin--angiotensin--aldosterone system.

The bolus ip. administration of a SRIF antagonist (SRIF-A) (60 nM/rat) significantly increased renin activity (PRA) and plasma aldosterone concentration (PAC) in rats, without affecting natremia, kalaemia and the blood levels of ACTH or corticosterone. SRIF-A also raised PAC in rats whose renin-angiotensin system had been pharmacologically interrupted by combined captopril/angiotensin-II infusion and in which PRA was very low. The ip. injection of an equimolar dose of SRIF completely reversed these effects of SRIF-A, but the administration of SRIF alone did not affect either PRA or PAC. Taken together, these data would suggest that, in the rat, endogenous SRIF exerts, under basal conditions, a two-fold maximum tonic inhibitory effect on both renin release by kidneys and aldosterone secretion by zona glomerulosa cells.

Adrenocorticotropic Hormone↗
PubMed1992

Does isradipine exert a special early-morning blood pressure-lowering effect?

The blood pressure-lowering effect of isradipine at 1.25-2.5 mg twice daily (taken at 0700 and 1900 h) was assessed in a double-blind study involving 28 men with mild-to-moderate hypertension. After a 4-week placebo period, patients were randomized to receive either isradipine (group I) or placebo (group II) for 8 weeks. At the end of the placebo and active-treatment periods, patients were evaluated by 24-h ambulatory blood pressure monitoring. Data were analyzed according to two time periods: daytime, 1000-2300 h; nighttime and early morning, 2300-1000 h. Intersubject analyses were performed comparing values at the end of placebo with those at the end of active treatment. Intrasubject two-way analysis of variance showed that the time of day or night had no influence on blood pressure changes. Comparison of systolic (SBP) and diastolic (DBP) blood pressures with isradipine indicated that there were significantly greater average decreases in SBP at 0600-0800 h than at 1800-2000 h (p = 0.038), and at 0800-1100 h than at 2000-2300 h (p = 0.045). This was also true for the average decreases in DBP (p = 0.006). In conclusion, isradipine exerts blood pressure control throughout 24 h with a pronounced action during the early morning (0600-0800 h) period.

Adult↗
PubMed1992

A new instrument for controlling pressure exerted on the sclera during contact Nd:YAG laser cyclodestruction.

We tested the device described by Rol et al in their article in this issue, designed to define and precisely control the pressure applied to the sclera during contact cyclodestruction with a cw-Nd:YAG laser. Since scleral transparency, and hence transmission of laser energy, depends on the pressure applied, control of this parameter represents an important advance toward the goal of standardizing the cyclodestructive procedure. In eight of nine cadaver pig eyes, pressure was exerted on the sclera using the pressure-controlling device, with a setting of 0.25 N for two of these eyes, and one of 0.4 N for the other six. In the remaining eye, pressure was controlled intuitively by an experienced surgeon. Applying forces of 0.25 or 0.4 N yielded similar success rates, although these fluctuated greatly even under constant pressure conditions (from 17% to 50% at 0.25 N; from 27% to 42% at 0.4 N). The highest success rate (55%) was achieved by the intuitively controlled pressure irradiations of the experienced surgeon. The variation in coagulation intensity that occurred despite constant pressure suggests that additional factors contribute to the results achieved. Nonetheless, this pressure-controlling probe represents an important achievement. It will permit not only the novice but even experienced operators to adhere unambiguously to a protocol of quantitative, reproducible parameters, and will also help researchers to better understand the relationship between energy delivered and intraocular pressure reduction achieved in contact cyclophotocoagulation.

Animals↗
PubMed1992

Role of neuroendocrine hormones in murine T cell development. Growth hormone exerts thymopoietic effects in vivo.

Growth hormone (GH) and other neuroendocrine mediators have been implicated previously in T cell development. We therefore examined thymic development in DW/J dwarf mice. DW/J mice lack acidophilic anterior pituitary cells and consequently are totally deficient in the production of GH, as well as other neuroendocrine hormones. DW/J dwarf mice had greatly hypoplastic thymi that continued to decrease in size as the mice aged. Characterization of the different T cell subpopulations within the thymi of dwarf mice indicated a deficiency in CD4+/CD8+ double-positive thymocytes. This deficiency of progenitor cells became more complete as the mice aged culminating in the total disappearance of this subpopulation in some dwarf mice > 3 mo of age. Analysis of the lymph nodes indicated that a population of double-positive (CD4/CD8) T cells appeared in some mice concurrent with the disappearance of double-positive cells in the thymus suggesting that these thymocytes may have migrated to the periphery. However, peripheral T cells from dwarf mice did exhibit Ag-specific responses indicating that these mice have functional T cells. Treatment of the mice with recombinant human GH, which binds both murine growth hormone receptors and murine prolactin receptors, or ovine GH, which binds murine growth hormone receptors but not murine prolactin receptors, resulted in an increase in thymic size and the reappearance of the CD4+/CD8+ double-positive cells within the thymus. Additionally, after GH treatment, the double-positive cells disappeared from the lymph nodes. The thymi of mice treated with GH failed to attain normal size but did develop a normal distribution of T cell progenitors. Thus, GH exerts significant thymopoietic effects in vivo. Neuroendocrine hormones may be important for normal T cell differentiation to occur within the murine thymus.

Animals↗
PubMed1992

Effects of brief, heavy exertion on circulating lymphocyte subpopulations and proliferative response.

Ten healthy males (mean age 22.3 +/- 0.8 yr) pedaled with maximal effort for 30 s against a workload adjusted prior to the start of the test to 0.98 N.kg body mass-1. Blood samples were collected before, and 3 min and 1 h following exercise. Peak and average power mean values were 1020 +/- 51 and 738 +/- 34 W, respectively. Total leukocytes increased 40% in response to the exercise bout, but were 16% below pretest levels after 1 h of recovery (F = 123, P < 0.001). Neutrophils and lymphocytes represented approximately 60% and 30% of the leukocytosis, respectively. Lymphocytes increased 30% following exercise, but were 36% below pretest levels after 1 h recovery (F = 56.4, P < 0.001). The post-test lymphocytosis can be explained primarily from the 176% increase in natural killer cells (NK) and 28% increase in cytotoxic/suppressor T cells, while the 1-h recovery lymphopenia occurred because of a sharp decrease in total T cells and a moderate decrease in NK cells. No significant changes in lymphocyte proliferative response or serum immunoglobulin levels were found when appropriate adjustments for changes in plasma volume or lymphocyte subset changes were made. Plasma epinephrine increased 300% in response to the exercise bout, and best explains the measured changes in circulating levels of lymphocyte subsets. These results demonstrate that changes in circulating levels of leukocyte and lymphocyte subsets, especially NK cells, occur rapidly in response to 30 s of brief, heavy exertion.

Adult↗
PubMedDate not supplied

Dual action of cyclin-dependent kinase inhibitors: induction of cell cycle arrest and apoptosis. A comparison of the effects exerted by roscovitine and cisplatin.

Cyclin-dependent kinases (CDKs) have recently raised considerable interest in view of their key role in the regulation of the cell cycle progression. In proliferating cells, distinct CDKs associated with specific cyclins coordinate in an orchestrated way the appropriate transition between different phases of the cell cycle. Mutations and/or aberrant expression of distinct CDKs and their regulatory components lead to uncontrolled proliferation and finally to carcinogenesis. However, in post-mitotic neurons, all CDKs with the exception of CDK5 are silent. CDK5, a proline-directed serine/threonine kinase exhibiting a close structural homology to the mitotic CDKs, binds to p35, the neuron-specific regulatory subunit of CDK5. CDK5 is very abundant in mature neurons and seems to regulate neurotransmitter release through phosphorylation and down-regulation of calcium channel activity. Therefore, the inhibition of CDKs in neurons after oxidative stress and in neurodegenerative disorders has a protective action. Selective CDKs inhibitors were developed as promising drugs for cancer therapy due to their ability to arrest cell cycle progression. The aim of this study was to compare the anti-proliferative effect of roscovitine (ROSC), a potent CDKs inhibitor, with that of cisplatin (CP) on human breast cancer MCF-7 cells. ROSC exerted stronger inhibitory effect on proliferation and cell cycle progression of MCF-7 than CP. Accumulation of G(2)/M arrested cells starting 6 h after onset of ROSC treatment coincided with a strong up-regulation of the p53. Reconstitution with caspase-3 sensitized MCF-7 cells to CP action. It implicates that ROSC inhibits more selectively and efficaciously the proliferation of human breast carcinoma cells.

Apoptosis↗
PubMed2004

The citrus-derived flavonoid naringenin exerts uterotrophic effects in female mice at human relevant doses.

Gavage administration of the citrus flavonoid naringenin, 3',4,5,7-tetrahydroxyflavanon for 4 consecutive days, to immature female mice (postnatal day 17-20) at 4 or 100 mg/kg b.wt. significantly increased uterine weights 3 and 4 times, respectively. Analysis of uterine oestrogen receptor alpha revealed that naringenin significantly increased the cytosolic concentration of oestrogen receptor alpha, whereas in nuclei the oestrogen receptor alpha concentration was significantly decreased as compared to the solvent control. This was in contrast to the positive control 17 beta-oestradiolacetate which acted as a true oestrogen by increasing the concentration of both total and nuclear oestrogen receptor alpha. Both naringenin and 17 beta-oestradiolacetate, however, significantly, induced nuclear oestrogen receptor alpha in the liver, suggesting a tissue specific effect of naringenin on oestrogen receptor alpha distribution. In order to investigate the tissue levels at which the uterotrophic effect was observed, the distribution of an oral dose of tritiated naringenin (4 mg/kg) was investigated in 3-week-old female mice. The radioactivity content (ng naringenin equivalents/g tissue) was found to be highest in the gastrointestinal-tract, followed by the kidneys and liver. Uterus and ovaries were also found to contain relatively high and approximately equal amounts of naringenin. The concentration of naringenin in uterus and ovaries was found to be ten times higher as compared to the mammary tissue. The urinary excretion of more than 25% of the administered dose, within 8 hr after dosing indicated that naringenin is absorbed extensively in mice. The plasma concentration of 0.5 microM found in the present study is similar to the peak plasma concentration of naringenin (0.6 microM) observed in man following ingestion of 400-760 ml of orange juice (Erlund et al. 2001). This could be taken to suggests that ingestion of orange juice and other citrus fruits and juices may give rise to sufficiently high tissue levels of naringenin in man to exert a biological effect.

Administration, Oral↗
PubMedDate not supplied

[The relation between the HLA-DRB1*1501 allele and the severity of multiple sclerosis in a sample of the Spanish population from the Balearic Islands: the influence exerted by sex].

INTRODUCTION: There is some controversy about the possible relation between HLA-DR2 (DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0602) and the severity of multiple sclerosis (MS), which could be due, at least in part, to methodological differences among the different studies dealing with this subject and/or to a lack of phenotypic homogeneity within the series of patients. AIMS: This study aims to contribute information about the possible relation between DR2 (more specifically the HLA-DRB1*1501 allele) and the severity of MS. PATIENTS AND METHODS: We conducted a study of 43 individuals with clinically defined MS, whose degree of severity was determined using Kurtzke's EDSS, and 107 controls from a similar ethnic origin. DETERMINATIONS: HLA typing by PCR-SSO and PCR-SSP, analysis of oligoclonal IgG bands in CSF by isoelectric focusing, and quantification of the intrathecal synthesis of IgG (IgG index, IgG ratio, Reiber's formula and Tourtellotte's formula). STATISTICS: Chi2 test, Mann-Whitney test and Kendall correlation coefficient. RESULTS: DRB1*1501 is associated with the presence of MS only in females and with lower severity of the disease only in males. These associations do not appear to depend on any kind of effect exerted by DRB1*1501 on the intrathecal synthesis of IgG that differs between the two sexes. CONCLUSIONS: The absence of a relation between DRB1*1501 and the severity of MS reported in many studies could be due to not stratifying the patients according to sex. Our findings emphasise how important it is in genetic studies of complex traits to reduce the phenotypic heterogeneity of patients as much as possible.

Adolescent↗
PubMedDate not supplied

The combination metformin/glyburide exerts its hypoglycemic effect mainly by increasing insulin secretion: a controlled, randomized, double-blind, crossover study.

The aim of the present study was to describe the mechanism by which the combination glyburide/metformin exerts its additive hypoglycemic effects. This is a double-blind, randomized and crossover clinical trial. Patients (n = 20) were included in a run-in period of 8 weeks in which an isocaloric diet was prescribed. If they did not achieve the treatment goals (n = 15), they received glyburide, metformin or combined treatment for 10 weeks each using three possible sequences. The dosage was adjusted to reach fasting plasma glucose (FPG) < 7.7 mmol/l. Treatment periods were separated by a 6-12 week washout period. At the beginning and the end of every treatment, insulin sensitivity and insulin secretion were measured by means of a minimal model and an oral glucose tolerance test. All treatment periods were completed by 12 cases. The glycemic goal was reached in 1 case during metformin, in 5 during glyburide and in 10 during the combination. The greatest reduction in HbA1c was achieved during the combination (HbA1c 11 +/- 1.6 vs 9.8 +/- 1.9 vs 9.0 +/- 2.1% for metformin, glyburide and the combination, p < 0.001). Increased insulin secretion was the explanation for the additive effects of the combination (percentual change in acute insulin response during the minimal model = 5.8 vs 51.5 vs 88.2% for metformin, glyburide and the combination, p < 0.05). No change in insulin sensitivity resulted from the treatments. In conclusion, the additive hypoglycemic effects of the combination glyburide/metformin was caused by increased insulin secretion.

Adult↗
PubMed1992

[Multiorgan damage in exertion heatstroke].

The paper reports a fatal case of exertion heat stroke. The etiopathogenetic, clinical and therapeutic aspects of the case are described; although rarely observed, this pathology must be taken into account by the intensive care unit in order to ensure rapid aid and treatment in an attempt to modify the severe prognosis due to multiorgan damage which increases with the intensity and duration of hyperthermia.

Adult↗
PubMed2003

[Chronic exertional compartment syndrome (CECS)].

The chronic exertional compartment syndrome (CECS) consists of a disturbance of the muscular function of a compartment related to a rise in the intramuscular pressure of the aforementioned compartment, during an exercise. The most frequent location of this pathology is the leg. The 2 parts of this article are treating the subject. The clinical presentation is often not very specific and the realization of complementary investigations is essential to confirm the diagnosis. Among those, the measurement of the intramuscular pressures of all the compartments potentially accused, at rest, during an effort and especially in phase of recovery, represents the determining criteria. The physiopathological mechanisms implied in the syndrome and currently recognized, are also the object of this 1st part.

Chronic Disease↗
PubMed2003

[On the rational exertion for the prescriptions and drugs of TCM in preventing and treating SARS].

Based on the main schemes of the prevention and therapy for SARS issued by the state and provincial administrations of traditional Chinese medicine (TCM), the characters and regulations for the application and performance of TCM in preventing and treating SARS were studied by cluster analysis. Some problems in the rational exertions of TCM in preventing and treating SARS were also discussed. Some proposals for the rational uses of traditional Chinese drugs (TCD) in preventing and treating SARS were offered finally in this article.

Cluster Analysis↗
PubMed2004

Measurement of force exerted on footplates by centrifuge subjects.

INTRODUCTION: Increased G-tolerance in flight is usually achieved by isometric contraction of the muscles of the abdomen and of lower extremities, along with forceful expiration against a closed or partially closed glottis. Measurement and analysis of the forces developed by a pilot's leg muscles during +Gz acceleration is one of the steps needed to develop specialized physical conditioning programs. METHODS: We developed a system for continuous measurement of forces exerted on simulated rudder pedals in a human centrifuge. RESULTS: Data from five test subjects showed that the system could measure left-right asymmetry as well as individual differences in pressure patterns during acceleration. DISCUSSION: The results suggest that the measurement system could be useful in training pilots to increase the effectiveness of their anti-G straining maneuvers. Specifically, the system may help pilots learn to adjust their effort to the G profile.

Acceleration↗
PubMed1992

Growth hormone exerts hematopoietic growth-promoting effects in vivo and partially counteracts the myelosuppressive effects of azidothymidine.

Recombinant human growth hormone (rhGH) was administered to mice to determine its effect on hematopoiesis. BALB/c mice and mice with severe combined immune deficiency (SCID), which lack T cells and B cells, were administered intraperitoneal injections of rhGH for 7 days. Upon analysis, both strains of mice exhibited an increase in splenic and bone marrow hematopoietic progenitor cell content and cellularity, indicating that rhGH can act as a hematopoietic growth factor. C57BL/6 mice were then placed on azidothymidine (AZT). AZT is a reverse transcriptase inhibitor currently used as a treatment for acquired immune deficiency syndrome (AIDS), but which also produces significant myelotoxic effects. Treatment of mice with rhGH partially counteracted the myelosuppressive properties of AZT. Bone marrow cellularity, hematocrit values, white blood cell counts, and splenic hematopoietic progenitor cell content were all significantly increased if rhGH (20 micrograms injected intraperitoneally every other day) was concurrently administered with AZT. Administration of ovine GH (ovGH), which, unlike rhGH, has no effect on murine prolactin receptors, also prevented the erythroid-suppressive effects of AZT in mice, but had no significant effect on granulocyte counts. Thus, the effects of GH are mediated at least in part through GH receptors in vivo. Additionally, when mice were initially myelosuppressed by several weeks of AZT treatment, the subsequent administration of ovGH resulted in an increase in splenic hematopoietic progenitor cells. No significant pathologic effects were observed in mice receiving either repeated rhGH or ovGH injections. Thus, GH exerts significant direct hematopoietic growth-promoting effects in vivo and may be of potential clinical use to promote hematopoiesis in the face of myelotoxic therapy.

Animals↗
PubMed1978

[Frequencygrams due to the stimulation of dynamic gamma axons exerting type II effects].

Frequencygrams are graphs giving indirect information on the contraction of intrafusal muscle fibres. Frequencygrams of Cat spindle primary endings (flexor hallucis longus, soleus and peroneus brevis muscles) were recorded during repetitive stimulation of dynamic gamma axons exerting type II effects. The features of these frequencygrams (periodic increments whose frequency is equal to that of the stimulation and "driving") show that they can be ascribed to a relatively strong and fast intrafusal contraction. Two interpretations are considered.

Action Potentials↗
PubMedDate not supplied

Sasa health exerts a protective effect on Her2/NeuN mammary tumorigenesis.

Bamboo grass leaves of different Sasa species have been widely used in food and medicine in Eastern Asia for hundreds of years. Of special interest are Kumazasa (Sasa senanensis rehder) leaves used to prepare an alkaline extract known as Sasa Health. This extract was reported to inhibit both the development and growth of mammary tumors in a mammary tumor strain of virgin SHN mice (1). We found that Sasa Health exerts a significant protective effect on spontaneous mammary tumorigenesis in another mouse model of human breast cancer, the transgenic FVB-Her2/NeuN mouse model. Two cohorts of Her2/NeuN female mice of different age (eleven-week-old and twenty-four-week-old) chronically treated with Sasa Health in drinking water showed both a delay in the development of tumors and reduced tumor multiplicity. Sasa Health also induced inhibition of mammary duct branching and side bud development in association with reduced angiogenesis. Altogether these findings indicate that Sasa Health contains phytochemicals that can effectively retard spontaneous mammary tumorigenesis.

Animals↗