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PubMed1999

Metastases in axillary sentinel lymph nodes in breast cancer as detected by intensive histopathological work up.

AIM: To assess the value of the intensive histological work up of axillary sentinel lymph nodes (SLN) to demonstrate regional metastatic disease. METHODS: From a series of 58 successful lymphatic mapping procedures, 78 SLN were analysed by serial sections (mean of 49 levels/SLN) and by immunostaining to cytokeratin and epithelial membrane antigen, and the results compared with those obtained by assessing the central cross section. RESULTS: The central cross section would have failed to detect metastases in eight of 26 lymph nodes (31%) in patients with breast cancer metastasising to the SLN only. This would have led to a false negative node status in six of 21 patients (29%). Two micrometastases were detected with the aid of immunostains. CONCLUSIONS: The results suggest the need to examine SLN at multiple levels and to use immunohistochemistry in negative cases. Serial sections are also useful in the case of micrometastases, as some of these may convert to macrometastases at deeper levels. Multiple level investigation of SLN and immunohistochemistry in the event of the negativity of standard stains would result in improved staging and an increase in the proportion of node positive disease detected.

Axilla↗
PubMed1989

Work tolerance and subjective responses to wearing protective clothing and respirators during physical work.

This study examined work tolerance and subjective responses while performing two levels of work and wearing four types of protective ensembles. Nine males (mean age = 24.8 years, weight = 75.3 kg, VO2 max = 44.6 ml/kg min) each performed a series of eight experimental tests in random order, each lasting up to 180 min in duration. Work was performed on a motor-driven treadmill at a set walking speed and elevation which produced work intensities of either 30% or 60% of each subject's maximum aerobic capacity. Work/rest intervals were established based on anticipated SCBA refill requirements. Environmental temperature averaged 22.6 degrees C and average relative humidity was 55%. The four protective ensembles were: a control ensemble consisting of light work clothing (CONTROL); light work clothing with an open circuit self-contained breathing apparatus (SCBA); firefighter's turnout gear with SCBA (FF); and chemical protective clothing with SCBA (CHEM). Test duration (tolerance time) was determined by physiological responses reaching a predetermined indicator of high stress or by a 180-min limit. Physiological and subjective measurements obtained every 2.5 min included: heart rate, skin temperature, rectal temperature, and subjective ratings of perceived exertion, thermal sensation, and perspiration. The mean tolerance times were 155, 130, 26, and 73 min, respectively, for the CONTROL, SCBA, FF, and CHEM conditions during low intensity work; and 91, 23, 4, and 13 min, respectively, during high intensity work. Differences between ensemble and work intensity were significant. FF and CHEM heart rate responses did not reach a steady state, and rose rapidly compared to CONTROL and SCBA values. SCBA heart rates remained approximately 15 beats higher than the CONTROL ensemble during the tests. At the low work intensity, mean skin temperatures at the end of the test were 32.7, 33.1, 36.7, and 36.3 degrees C, while mean core temperatures were 37.6, 37.9, 37.9, and 38.5 degrees C, respectively. The subjective data indicated that, in general, subjects were able to perceive relative degrees of physiologic strain under laboratory conditions. Wearing protective clothing and respirators results in significant and potentially dangerous thermoregulatory and cardiovascular stress to the wearer even at low work intensities in a neutral environment. Physiologically and subjectively, firefighter's turnout gear (the heaviest ensemble) produced the most stress, followed by the CHEM, SCBA, and CONTROL protective ensembles.

Body Temperature↗
PubMed1984

Breathing pattern and occlusion pressure during moderate and heavy exercise.

We studied changes in breathing pattern and mouth occlusion pressure (P0.1) in 11 healthy subjects performing graded steady-state exercise on a cycle ergometer up to the maximal load sustainable for 4 min. With increasing work intensity both the tidal volume (VT) and end-inspiratory volume relations to inspiratory (TI) and expiratory (TE) durations were linear in the moderate work load range; in the high load range VT and end-inspiratory volume tended to plateau with further decreases in TI and TE. The ratio of TI to total breath duration (TI/Ttot) increased with work intensity. Intraindividual coefficients of variation for VT, breathing frequency (f), mean inspiratory flow (VT/TI), and other respiratory variables decreased with increasing work intensity, indicating that breath-to-breath variations in breathing pattern became smaller as the level of ventilation increased. P0.1 rose with VT/TI as a power function with an exponent averaging 1.5 (range 1.3-1.9), indicating that the ratio P0.1/(VT/TI), an index of respiratory system impedance, increased with VT/TI and work intensity. We conclude that in moderate and heavy exercise the work of inspiration at a given ventilation is reduced because of the increase in TI/Ttot, the impedance of the respiratory system increases with work intensity because of both an increase in f and a flow-dependent rise in airway resistance, and the neuromuscular inspiratory activity is reflexly augmented because of internal flow-resistive loading.

Adult↗
PubMed1987

Enteric colonization with antibiotic resistant bacteria in nurses working in intensive care units.

To determine whether nurses who worked in an intensive care unit (ICU) might acquire enteric colonization with Gram-negative aerobic bacteria from their patients, rectal swabs were obtained from the patients and nurses in the ICU, from nurses working in a coronary care unit (CCU) and from young women with urinary tract infection who had not been exposed to the hospital environment. The healthy women differed from the patients in that their enteric flora contained greater numbers of lactose fermenting bacteria, they were less often colonized by resistant organisms and when resistant bacteria were present they were less abundant than in the patients. Nurses who had been treated with antimicrobial agents during the preceding six months were colonized more often with antibiotic resistant enteric bacteria. There was no evidence of transmission of antibiotic resistant Escherichia coli from patients to nurses largely because this species had been virtually eliminated from the patients by intensive use of antimicrobial agents. Instead, several multiresistant species of Klebsiella, Citrobacter and Pseudomonas were isolated from the patients and ICU nurses. It was difficult, however, to define clearly patient-nurse controls who had no exposure to the ICU patients. These observations and those of other investigators emphasize the need for examination of control populations and of therapeutic use of antibiotics when examining the issue of environmental acquisition of antibiotic resistant bacteria.

Adolescent↗
PubMed1995

[An epidemiological study on the relationship between musculoskeletal disorders and work load].

965 workers engaged in working tasks of work intensity grade 2, 3, 4 (based on Chinese National Standard) were investigated on the musculoskeletal disorders with a questionnaire. The lumbar vertebra of 136 randomly chosen workers were also radiologically examined. The result revealed that the prevalence of low-back disorders was 51.2% on average and it was obviously correlated with such factors as age, standing, previous back injury, education level, sport activity, work intensity, working posture, satisfaction with the tools as well as work condition and house work. Heavy work load and unneutral working posture were proved to be the main factors as revealed by the multifactor analysis and further supported by the findings of X-ray examination.

Adult↗
PubMed2001

A model of oxidative phosphorylation in mammalian skeletal muscle.

A dynamic computer model of oxidative phosphorylation in oxidative mammalian skeletal muscle was developed. The previously published model of oxidative phosphorylation in isolated skeletal muscle mitochondria was extended by incorporation of the creatine kinase system (creatine kinase plus phosphocreatine/creatine pair), cytosolic proton production/consumption system (proton production/consumption by the creatine kinase-catalysed reaction, efflux/influx of protons), physiological size of the adenine nucleotide pool and some additional minor changes. Theoretical studies performed by means of the extended model demonstrated that the CK system, which allows for large changes in P(i) in relation to isolated mitochondria system, has no significant influence on the kinetic properties of oxidative phosphorylation, as inorganic phosphate only slightly modifies the relationship between the respiration rate and [ADP]. Computer simulations also suggested that the second-order dependence of oxidative phosphorylation on [ADP] proposed in the literature refers only to the ATP synthesis flux, but not to the oxygen consumption flux (the difference between these two fluxes being due to the proton leak). Next, time courses of changes in fluxes and metabolite concentrations during transition between different steady-states were simulated. The model suggests, in accordance with previous theoretical predictions, that activation of oxidative phosphorylation by an increase in [ADP] can (roughly) explain the behaviour of the system only at low work intensities, while at higher work intensities parallel activation of different steps of oxidative phosphorylation is involved.

Adenosine Diphosphate↗
PubMed2003

Effect of subjective and objective workload on asthenopia at VDU workplaces.

An ergophthalmological tool has been developed to investigate effects of subjective and objective workload on work-related visual complaints (asthenopia). In field studies on different visual display unit (VDU) workplaces effects of objective and subjective workload, work intensity, and work breaks (5-9 min/hour) could be found. It could be shown that during the first hours of VDU work, asthenopic complaints have the tendency to follow effective workload. With increasing working time the effect of a general and visual fatigue overlaps other reported visual complaints in the majority of cases.

Asthenopia↗
PubMed2004

[Covert infection of severe acute respiratory syndrome in health-care professionals and its relation to the workload and the type of work].

OBJECTIVE: To study severe acute respiratory syndrome (SARS) covert infection in health-care professionals and its relation to work intensity and type of work. METHODS: Specific antibodies to SARS virus in 1 127 serum specimens from health-care professionals who had a close contact history with patients of SARS and 92 healthy persons were assayed with ELISA. RESULTS: The health-care professionals consisted of 287 men and 840 women, aged 21 - 55 years (mean 34 +/- 9 years). The overall positive rate of specific IgG and IgM was 2.57% (29/1 127); the positive rates in nurses, doctors and laboratory workers, and supervisors were 3.46%, 1.41%, 2.86%, respectively. 34.5% of the infected worked in the ICU, and 65.5% in the general wards. None of them presented clinical SARS. Medical examination was also carried out for 313 people who had close contact with the 29 antibody positive health care professionals, but no clinical SARS was found. CONCLUSIONS: Covert infection can be found in the health-care professionals and it showed no contagiousness. The positive rate of specific antibodies was higher in ICU where the work intensity was higher. The positive rate in nurses was higher than in doctors.

Adult↗
PubMed1976

Effect of physical fitness on the adrenocortical response to exercise stress.

Serum corticosteroid (S.C.) responses were compared in two groups of middle-aged male subjects, one sedentary, one active (both N = 11, mean age 44 years), who performed graded bicycle ergometer exercise before (pre) and after (post) a 4 month physical fitness program. Pre-training exercise involved low and high work intensities which required similar percentage of predicted Vo2 max for the sedentary and active groups. Post-training exercise at identical work loads which resulted in lower work intensities due to training effects, was followed by increased work loads demanding higher work intensities in order to accommodate for the increased work capacity of the respective groups. The sedentary group (pre) and the active group (post) showed significant elevations in S.C. during high intensity exercise and recovery. The active group had significantly lower S.C. during low and high intensity exercise and recovery (pre), and during rest and low intensity exercise (post). The sedentary group had significantly lower S.C. at identical work loads which resulted in a reduction of relative work intensity from pre to post-traing tests. Results suggest both fitness status and training effects in the adrenocortical response to exercise stress, although psychological factors may be involved.

Adrenal Cortex Hormones↗
PubMed1995

The influence of isotonic exercise on cardiac hypertrophy in arterial hypertension: impact on cardiac function and on the capacity for aerobic work.

Intense physical training through isotonic exercises has controversial effects in individuals with moderate to severe hypertension. In this study, normotensive Wistar rats and rats with renovascular hypertension (Goldblatt II) were subjected to intense physical exercise involving two 50-min swimming sessions per day for a period of 12 weeks. At the end of the study, we evaluated the effect of training on arterial pressure, the capacity for aerobic work and cardiac function. Our results demonstrate that intense physical training has no effect on the arterial blood pressure of normotensive rats or of animals with moderate renovascular hypertension. Hypertensive animals with cardiac hypertrophy require a greater period of training in order to attain the same capacity for aerobic work as normotensive rats. This difference may result from an inability of the former animals to increase cardiac compliance, thereby impeding more extensive usage of the Frank-Starling mechanism to subsequently increase the systolic cardiac performance. Cardiac hypertrophy induced by exercise did not summate with that induced by arterial hypertension. Physical exercise normalized the end-diastolic left ventricular pressure in hypertensive animals without any corresponding increase in the compliance of the chamber. The first derivative of left ventricular pulse pressure (+/- dP/dt) was greater in the hypertensive trained group than in the hypertensive sedentary rats. These observations suggest that a systolic dysfunction of the left ventricle involving an elevated residual volume secondary to arterial hypertension may be corrected by physical exercise such as swimming.

Aerobiosis↗
PubMed1998

Catecholamine and cortisol responses of horses to incremental exertion.

The responses of the plasma concentrations of catecholamines and cortisol in horses to varied relative intensities of exertion were examined. The plasma concentrations of cortisol, epinephrine and norepinephrine increased significantly (p < 0.05) with exertion. The plasma cortisol concentrations at relative work intensities of 48.3% +/- 1.4%, 82.3% +/- 2.0% and 99.6% +/- 0.4% of VO2max were 114%, 124%, and 126%, respectively, of those at rest, whereas the plasma epinephrine concentrations were 239%, 772% and 3483%, and the norepinephrine concentrations were 138%, 255%, and 1121% of the values at rest. There was a significant (p < 0.0001) relationship between the plasma epinephrine and norepinephrine concentrations. The blood lactate concentration and the plasma epinephrine and norepinephrine concentrations were significantly (p < 0.0001) related, as were the relative work intensity (%VO2max) and the plasma epinephrine and norepinephrine concentrations. The relationships between the plasma cortisol concentration and work intensity or blood lactate concentration were not significant (p > 0.05). This study demonstrates a relationship between work intensity and indicators of adrenal medullary and sympathetic activity during brief exertion in horses.

Adrenal Medulla↗
PubMed2002

Participation in labor-intensive public works program (LIPWP): effect on staple crop production in southeastern Botswana.

A labor-intensive public works program (LIPWP) aims to improve the income of rural households. One of the common criticisms of the LIPWP is that it is a disincentive for staple crop production. This study, conducted between February and May 2000, examined the association between participation in an LIPWP and staple crop production in southeastern Botswana. Participant households were those with at least one member on a semipermanent LIPWP. A control group was drawn from households that were eligible to participate in the LIPWP. All participants in the LIPWP were included, while nonparticipant households were randomly selected. A structured questionnaire was administered to 160 control and 153 participant households. The odds of having no staple crop in the control group were 1.8 times (95% CI, 0.98 to 3.54) higher than that of the LIPWP participants (p = .087), while the odds of having no staple crop in a household with a head between 45 and 64 years of age were 2.5 times (95% CI, 1.06 to 5.96) higher than that of a household with a head less than 45 years old (p < .037). Having more than 10 livestock equivalent units reduced the risk of having no harvest by 40% (95% CI, 0.29 to 1.12). The view that participation in the LIPWP results in reduced staple crop production does not seem to be supported by our data.

Adult↗
PubMed1998

Yeast carriage on hands of hospital personnel working in intensive care units.

The frequency and distribution of yeast carriage on the hands of hospital personnel working in intensive care unit (ICUs), was investigated. Hand carriage of yeast and Candida species was 46 and 29%, respectively. Rhodotorula sp. and Candida parapsilosis were most frequently recovered. There was no significant difference in frequency or distribution of yeasts and Candida sp. recovered among the three ICUs. Seventeen C. parapsilosis isolates and three Candida albicans isolates were genotyped by electrophoretic karyotyping using contour-clamped homogenous electric-field gel electrophoresis. Eleven separate types of C. parapsilosis and two types of C. albicans were identified. There was no common genotype among these isolates, even within the same unit. We conclude that yeast carriage on the hands of personnel working in ICU is common, but these yeasts are usually not acquired from a common source in the ICU.

Candida↗
PubMed2002

Changes in blood volume and oxygenation level in a working muscle during a crank cycle.

PURPOSE: This study examined circulatory and metabolic changes in a working muscle during a crank cycle in a pedaling exercise with near-infrared spectroscopy (NIRS). METHODS: NIRS measurements sampled under stable metabolic and cadence conditions during incremental pedaling exercise were reordered according to the crank angles whose signals were obtained in eight male subjects. RESULTS: The reordered changes in muscle blood volume during a crank cycle demonstrated a pattern change that corresponded to changes in pedal force and electrical muscle activity for pedal thrust. The top and bottom peaks for muscle blood volume change at work intensities of 180 W and 220 W always preceded (88 +/- 32 and 92 +/- 23 ms, respectively) those for muscle oxygenation changes. Significant differences in the level of NIRS parameters (muscle blood volume and oxygenation level) among work intensities were noted with a common shape in curve changes related to pedal force. In addition, a temporary increase in muscle blood volume following a pedal thrust was detected at work intensities higher than moderate. This temporary increase in muscle blood volume might reflect muscle blood flow restriction caused by pedal thrusts. CONCLUSION: The results suggest that circulatory and metabolic conditions of a working muscle can be easily affected during pedaling exercise by work intensity. The present method, reordering of NIRS parameters against crank angle, serves as a useful measure in providing additional findings of circulatory dynamics and metabolic changes in a working muscle during pedaling exercise.

Adult↗
PubMed1994

The role of central command in ventilatory control during static exercise.

The role of central command in the respiratory response to 15 min of rhythmic-static (isometric) exercise was studied in humans. Voluntary exercise (VE) was compared with electrically induced exercise (EE) at three different work intensities, i.e. 5%, 15% and 25% of maximal voluntary contraction. A group of 12 volunteers participated in the study and each of them performed six sessions. A session consisted of at least 5 min rest, 15 min rhythmic-static single leg exercise (4 s contraction/12 s relaxation) and at least 5 min recovery. Force, minute ventilation (VE) and oxygen uptake (VO2) were measured. In EE, both VE and VO2 increased continuously during the entire exercise period after an initial rapid increase at all three work intensities. Correlation between VE and VO2 was highly significant during EE. During all three work intensities of VE, VE and VO2 achieved a steady-state after the initial increase. During VE, VE did not correlate as closely with VO2 as during EE. All these findings indicate that central command was not imperative for an adequate ventilatory response to exercise within all three work intensities investigated. Without the influence of central command, correlation between VE and VO2 was even better than during VE.

Adult↗
PubMedDate not supplied

Effects of training on the tolerance to high-intensity exercise in patients with severe COPD.

BACKGROUND: There has been no systemic investigation of the effects of training on endurance at different high-intensity work rates in patients with COPD to date. OBJECTIVES: We wanted to determine the effects of intense endurance training on tolerance to several high-intensity work rates and to establish the relationship between power (WR) and its tolerable duration (t) (t = W'/(WR - CP), being W', the curvature constant, thought to be reflective of anaerobic energy availability and/or tolerance to the uncomfortable sensations associated with the high-intensity exercise, and CP the critical power. METHODS: We studied 27 patients: age 62 +/- 5 years; FEV(1) 1.2 +/- 0.2 liters. Before and after the intervention, the subjects randomly underwent 4 high-intensity constant WR exercise tests. The endurance times of the highest 3 tests were used. RESULTS: Ventilation reached approximately the same level in each of the tests. In response to the training, the average peak increased by 9 +/- 5% (p < 0.0001), CP by 14 +/- 12% (p < 0.0001) and W' 18 +/- 22% (p = 0.002). In 67% of the patients, CP increased, accompanied by changes in other related physiological variables of aerobic capacity. In the remaining 33%, W' increased but not CP. Smaller or no changes in the other variables of aerobic capacity were found in those subjects. This latter group was significantly older and had more hyperinflation (i.e. higher RV/TLC%). CONCLUSIONS: Our results suggest that neither an incremental nor a single endurance test at constant WR provides an adequate characterisation of exercise tolerance at other WRs. CP and W' appear to be important parameters characterizing exercise tolerance over a range high-intensity work rates and identifying two distinct types of response to training.

Exercise↗
PubMed2002

Functional and molecular MR imaging of angiogenesis: seeing the target, seeing it work.

Intensive research over the last years led to the discovery of multiple molecular pathways and intricate regulatory network controlling the growth and regression of blood vessels in general and angiogenesis in particular. The difficulties in elucidation of the regulation of angiogenesis, stems from the inherent complexity due to participation of many cell types, under a dominant impact of physiological and environmental effects of flow, perfusion, and oxygenation. Major advances were achieved with the use of sophisticated transgenic mice models engineered so as to provide spatially and temporally controlled expression of specific factors alone or in combination. In vivo analysis of these models frequently requires the use of non-invasive imaging modalities for measurement of functional parameters of the vasculature along with dynamic molecular information. Optical methods are extensively applied for the study of angiogenesis [Brown et al., 2001] but provide very limited tissue penetration. MRI offers the advantage of being non-invasive with uniform and relatively high spatial resolution for deep tissues. Multiple MRI approaches for monitoring angiogenesis were developed over the last years, each looking at a particular step in the process. The aim of this paper is to analyze the clinical, pharmaceutical, and biological needs for imaging of angiogenesis, and to critically evaluate the strengths and weaknesses of functional and molecular imaging for monitoring angiogenesis. The inherent problem of validation of different measures of angiogenesis, and the advantages and limitations associated with application of MRI based methods, as surrogates for other measurements of angiogenesis will be discussed. The terms molecular imaging and functional imaging are frequently loosely defined with a significant overlap between the two. For the sake of this paper we will apply a narrower definition of both terms, where molecular imaging will apply to methods directed towards detection of specific biological molecules that participate directly in (regulation of) a physiological process; while functional imaging will be used to describe those methods that aim to detect the physiological response to a defined (molecular) stimulus.

Animals↗
PubMed1991

The physiological cost of wearing a disposable respirator.

In order to gain an understanding of the physiological stresses imposed by the wearing of a single-use disposable respirator, a series of experiments was done to measure the cardiopulmonary effects of wearing the respirator (heart rate, respiratory rate, and blood pressure); resistance to breathing while wearing a respirator; and heat stress imposed by the use of a respirator (changes in inspired and expired air temperature). Ten men, ages 24 to 35, of varying fitness levels, served as volunteers in the studies. All the men exercised on a treadmill both with and without 3M Model 8715 disposable respirators. Workloads corresponding to light, moderate, and heavy levels were calculated for each volunteer based on his maximal oxygen uptake. As work intensity increased, an increase in breathing resistance was found. Peak resistances were in the range of +/- 2 cm water. Work-intensity level increases in respiratory rates were found with and without the respirators, but the respirator use trial had a significantly increased respiratory rate. Heart rate also showed a dose-related increase as work intensity increased and was significantly greater in the respirator trials at heavy levels of work and during recovery. Systolic blood pressure showed a biphasic response to respirator use, being significantly lower at rest and higher at high levels of work. Diastolic blood pressure changes were less dramatic but were elevated in the respirator trials. Clinically important increases in blood pressure were found in two volunteers when respirators were worn. Air temperatures immediately anterior to the face were, on average, 7.5 degrees C higher in the respirator trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗