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PubMed1992

Age variation in the upper limit of hearing.

The upper limit of hearing was measured in 6105 otologically normal ears of subjects ranging in age from 5 to 89 years. The results are as follows: in each age group from 5 to 59 years in both sexes, the upper limit of hearing showed an approximately normal distribution if a logarithmic scale was used for the upper limit of hearing axis. The mode of the distribution shifted to a lower frequency with increasing age. Over age 60 years, the distribution became much wider. Standard upper limit age curves were established by calculating 10th, 25th, 50th, 75th and 90th percentiles for each age group. From early childhood where no age variation was recognized in conventional audiometry, deterioration of the upper limit of hearing was already in progress. This deterioration was slight between ages 25 and 39 but at ages over 40 it was accelerated and led to so-called presbycousis. The upper limit of hearing was found to be one of the best parameters for showing the quantitative age-related changes in hearing.

Adolescent↗
PubMed1990

Restricted activation of general amino acid control under conditions of glutamine limitation in Neurospora crassa.

In Neurospora crassa limitation for single amino acids normally results in increased formation of enzymes required for amino acid synthesis via 'general amino acid control'. Glutamine limitation, however, led to comparatively low and delayed derepression of enzyme synthesis. Nitrate reductase activity increased steeply under these conditions confirming that de novo protein synthesis could occur. Derepression levels were unaffected by addition of glutamine-derived metabolites. Only small and delayed increases in mRNA levels occurred for the anabolic enzyme genes arg-12, his-3 and trp-1 under conditions of glutamine limitation in contrast to the immediate and far larger increase found on histidine limitation. The trans-acting regulatory gene of general amino acid control in Neurospora, cpc-1, responded with a significant increase in mRNA level to histidine and to glutamine limitation. The restricted response of the amino acid synthesis genes could imply a post-transcriptional block to the positive regulatory function of cpc-1 under condition of glutamine limitation. The results suggest that the expression of general amino acid control is restricted under conditions of inadequate nitrogen supply.

Alcohol Oxidoreductases↗
PubMed1976

Growth and physiology of Candida utilis NCYC 321 in potassium-limited chemostat culture.

When grown in a defined simple salts medium, plus vitamins, Candida utilis displayed an absolute requirement for potassium. But the potassium content of this yeast was exceedingly variable and, with aerobic chemostat cultures (grown at a dilution rate of 0.1 h-1; 30 degrees C; pH 5.5), was low (less than 0.2%, w/w) when they were potassium-limited and high (greater than 2%, w/w) when glucose-limited. With potassium-limited cultures, the cell-bound potassium content also varied markedly with growth rate, though hardly at all with glucose-limited cultures; magnesium- and phosphate-limited cultures gave intermediate responses. Changes in cell-bound potassium content correlated only weakly with changes in the cellular contents of magnesium, phosphate and RNA, but strongly with changes in both the Yglucose and Y0 values, indicating an involvement of potassium in the generation of energy by oxidative phosphorylation reactions and/or the utilization of this energy for growth processes. Studies with isolated mitochondria revealed that potassium-limited organisms had a changed content of cytochrome b relative to cytochrome a, and lacked coupling at either site 2 or site 3 of the respiratory chain. These results are discussed in relation to the reported functions of potassium in the growth of micro-organisms, and the organizational differences between prokaryotic and eukaryotic cells.

Candida↗
PubMed1995

Clinicians' opinions on alarm limits and urgency of therapeutic responses.

To survey the routine use of bedside multivariable monitors in monitoring cardiac postoperative patients, 23 experienced anesthesiologists and cardiac surgeons were first asked to list which variables and what limit alarms they used. Then they defined to what extent the variables' values were allowed to deviate before therapeutic actions were needed. Typically, limit alarms were applied to heart rate and end-tidal CO2. For clinical assessment of a patient's state, the clinicians usually observed the heart rate and the systemic arterial blood pressures, but placed less emphasis on the pulmonary arterial pressures. Clinicians had similar opinions on alert limits for monitoring less extensive physiological deviations and on alarm limits for warning of a critical situation. Person-to-person tolerance of suboptimal monitored values varied. No correlation was found between the limit values and how long these values were tolerated without therapeutic response. However, the inquiry provided information on setting limits for alerts and alarms, and on experienced clinicians' decision-making during postoperative intensive care of cardiac patients.

Anesthesiology↗
PubMed1999

Limited hemorrhoidectomy: results and long-term follow-up.

PURPOSE: Three-column excision has traditionally been the preferred treatment for symptomatic hemorrhoidal disease in patients failing nonoperative treatments. There are few data evaluating focused surgical management of only the symptomatic hemorrhoidal complexes by limited hemorrhoidectomy. The purpose of this study was to evaluate patient outcome after one-quadrant or two-quadrant hemorrhoidectomy for symptomatic hemorrhoids. METHODS: We retrospectively studied patients undergoing a one-quadrant or two-quadrant hemorrhoidectomy as initial surgical treatment of symptomatic columns from April 1987 to July 1993. Patients undergoing a traditional three-quadrant hemorrhoidectomy during the same time period were used as controls. Statistical analysis was used to determine significance. RESULTS: There were 115 evaluable patients who had undergone a one-quadrant or two-quadrant hemorrhoidectomy. One hundred thirty-three three-quadrant patients were studied as the control group. The mean follow-up was 8.1 years and 7.2 years for the limited and three-quadrant hemorrhoidectomy group, respectively. The majority of patients (96 percent limited and 98 percent three-quadrant) experienced initial relief of symptoms after surgery. There was no significant difference between the two groups in the development of recurrent anorectal symptoms (34 percent limited and 29 percent three-quadrant), in the need for additional medical therapy (11.3 percent limited and 15.8 percent three-quadrant), or in the need for additional interventional therapy (2.9 percent limited and 0.8 percent three-quadrant). No patients in either group required additional surgical hemorrhoidectomy. CONCLUSIONS: The majority of patients with hemorrhoidal disease requiring excision can be managed effectively by focused treatment of the problematic columns. With this approach fewer than 2 percent of patients will require further procedural intervention of their hemorrhoidal disease.

Adult↗
PubMed1998

Limited surgery for early gastric cancer in cardia.

BACKGROUND: Because there are some difficulties with the diagnosis of invasion or the endoscopic resection technique, almost all gastric tumors are resected surgically. Surgeons now are performing a limited operation for early gastric cancer of the upper stomach (EGCUS) without lymph node metastasis. This paper discusses and evaluates the surgical technique and the results of the limited operation for EGCUS. PATIENTS AND METHODS: Since 1988, a total of 34 patients with EGCUS, diagnosed as intramucosal invasion, have undergone a limited operation--fundectomy--which includes a limited proximal gastrectomy, a limited lymph node dissection, and a procedure preserving the vagal nerve. The surgical risk, postoperative complications, and survival rates of the fundectomy patients (group A) were compared with those of patients undergoing a total gastrectomy for EGCUS (group B). RESULTS: Blood loss was lower in group A (300+/-193 mL) than in group B (555+/-316 mL) (P <.05). The incidence of postoperative pancreatic fistula also was lower in group A (0%) than in group B (15.0%) (P <.05). All patients in both groups (except one who died of a cerebral infarction) are alive without recurrence. CONCLUSION: Compared to the results of a total gastrectomy, performance of a limited fundectomy for EGCUS decreased surgical risk and postoperative complications without decreasing the survival rate.

Adult↗
PubMed2005

The effect of limited overfeeding during growth on muscle characteristics: a pig model.

Energy restriction affects the hypothalamus, leading to a decrease in production of reproductive and thyroid hormones. A decrease in reproductive hormones affects fertility and a decrease in thyroid hormones affects muscle metabolism. A pig model has been used to determine that reproductive function is negatively affected if the normal practice of overfeeding is limited during the late luteal phase of the estrous cycle. We used a sub-set of pigs from this study to examine effects of limiting overfeeding on thyroid hormones and skeletal muscle (i.e. maximal enzyme activities, and muscle fibre characteristics). Eighteen rapidly growing gilts were randomized into three groups: 1) feeding a high plane of nutrition throughout the first 15 days of the estrous cycle; 2) limited overfeeding (25% below the first group) for first 7 days of the estrous cycle (early luteal phase), followed by a high plane of nutrition for days 8-15 (late luteal phase); and 3) high plane of nutrition throughout the first 7 days of the estrous cycle, followed by 8 days of limited overfeeding. Muscle biopsies were collected from the triceps brachii, and blood samples were collected for assessment of thyroid hormones at days 0 (baseline), 8 and 16. There was no effect of limited overfeeding on thyroid hormones, maximal enzyme activities, muscle fibre area or muscle fibre type. Limited overfeeding in rapidly growing pigs does not affect thyroid hormone status or muscle characteristics.

Animal Feed↗
PubMed2004

Functional limitations and poor physical performance as independent risk factors for self-reported fractures in older persons.

OBJECTIVE: This study examined whether three aspects of functioning (i.e., functional limitations, physical performance, and physical activity) were associated with fractures in older men and women. DESIGN: A 3-year prospective cohort study. PARTICIPANTS AND SETTING: A total of 715 men and 762 women, aged 65 years and older, of the population-based Longitudinal Aging Study Amsterdam. MEASUREMENTS: During an interview at home, three aspects of functioning were assessed: functional limitations (what people say they can do), physical performance, i.e., three performance tests and handgrip strength (what people are able to do), and physical activity (what people actually do). Afterward, a follow-up on fractures was conducted for 3 years. RESULTS: 77 patients (5.2%) suffered a fracture during 3-year follow-up. Most patients suffered a hip fracture (1.6%) or a wrist fracture (1.4%). The fracture rate per 1,000 person-years was 20.1. During 3-year follow-up, a fracture was reported by 12%, 10%, 12%, and 6% of the respondents with functional limitations, low performance test score, poor handgrip strength, and low physical activity, respectively. Using Cox proportional hazard analysis, functional limitations (RR = 3.5; 95% CI, 2.1 to 6.0), low performance test score (RR = 1.9; 95% CI, 1.1 to 3.3), low handgrip strength (RR = 2.5; 95% CI, 1.5 to 4.1), and low physical activity (RR = 1.9; 95% CI, 1.1 to 3.5) were significantly associated with fractures after adjustment for age and sex. Functional limitations (RR = 3.2; 95% CI, 1.8 to 5.5), low performance test score (RR = 1.8; 95% CI, 1.0 to 3.3) and low handgrip strength (RR = 2.0; 95% CI, 1.1 to 3.6) remained significantly associated with fractures after additional adjustment for body composition, chronic diseases, psychosocial factors, life style factors, and the other levels of functioning. No significant interaction terms were found. CONCLUSIONS: Functional limitations and poor physical performance were independent risk factors for fractures.

Activities of Daily Living↗
PubMed2005

Vertebral deformity, back symptoms, and functional limitations among older women: the Framingham Study.

Vertebral deformity is the most common manifestation of osteoporosis. The purpose of this study was to determine the relation between incident vertebral deformity and back symptoms; and limitations in nine specific functional activities. Subjects were participants in the Framingham Study, a longitudinal, population-based sample involving residents of Framingham, MA, USA. Subjects consisted of 444 surviving female members of the original cohort who had baseline (1968-1975) and follow-up (1992-1993) spine radiographs evaluated for deformity using a semiquantitative scale. Ages ranged from 72 to 96 years. At the follow-up examination, subjects were asked if they experienced pain, aching, or stiffness in their back on most days and if they had difficulty performing nine specific functional skills. We found that incident vertebral deformity was associated with limitations in several functional activities, most notably, pushing or pulling a large object (OR 2.51, 95% confidence interval 1.40, 4.52). For most activities, there was no increase in the risk of functional limitations among women with vertebral deformity who did not report back symptoms at the end of the follow-up compared with those without vertebral deformity or back symptoms. For several functional activities, individuals with both vertebral deformity and back symptoms had greater limitations than would be expected from the additive contribution of both conditions. Back symptoms were associated with limitations in most functional activities, even in the absence of vertebral deformity. Efforts to prevent and treat back pain, independent of vertebral deformity status, might help to reduce functional limitations in older women.

Activities of Daily Living↗
PubMed2001

Comparison of detection limits in environmental analysis--is it possible? An approach on quality assurance in the lower working range by verification.

Detection limit, reporting limit and limit of quantitation are analytical parameters which describe the power of analytical methods. These parameters are used for internal quality assurance and externally for competing, especially in the case of trace analysis in environmental compartments. The wide variety of possibilities for computing or obtaining these measures in literature and in legislative rules makes any comparison difficult. Additionally, a host of terms have been used within the analytical community to describe detection and quantitation capabilities. Without trying to create an order for the variety of terms, this paper is aimed at providing a practical proposal for answering the main questions for the analysts concerning quality measures above. These main questions and related parameters were explained and graphically demonstrated. Estimation and verification of these parameters are the two steps to get real measures. A rule for a practical verification is given in a table, where the analyst can read out what to measure, what to estimate and which criteria have to be fulfilled. In this manner verified parameters detection limit, reporting limit and limit of quantitation now are comparable and the analyst himself is responsible to the unambiguity and reliability of these measures.

Journal Article↗
PubMed1998

Consideration on a limit for lifetime occupational radiation exposure.

Annual dose limits in occupational radiation exposure are merely a secondary constraint in addition to the primary rule of dose reduction and justification. The limits may, therefore, be reached only in rare, special cases. However, in principle, there might be cases in which the annual limit is continuously exhausted throughout a working life; a high total dose of 0.8 Sv could then be reached. In view of this possibility, there have been considerations of an added restriction by limiting the lifetime occupational dose to 0.4 Sv. The implications of such lifetime doses are considered, and it is shown that an exposure up to the maximum of 0.8 Sv will lead to the need for compensation, if a leukaemia were to occur in the exposed worker. A lifetime dose of 0.4 Sv equally spread over a working life will not lead to the critical value of the probability of causation in excess of 0.5. Nevertheless, it could cause such critical values when it is accumulated during shorter periods. More decisive than the probabilities of causation are, however, the absolute numbers of excess cases of leukaemia due to the occupational exposure. It is seen that less than one excess case would be expected if a group of 100 workers were all exposed to the maximum of 0.8 Sv. Since lifetime doses of 0.8 or 0.4 Sv will be accumulated in very few cases and only with special justification, there appears to be little need to introduce a further limit of lifetime exposure in addition to the current annual limit.

Adult↗
PubMed2003

Nitrogen limitation of growth and nutrient dynamics in a disturbed mangrove forest, Indian River Lagoon, Florida.

The objectives of this study were to determine effects of nutrient enrichment on plant growth, nutrient dynamics, and photosynthesis in a disturbed mangrove forest in an abandoned mosquito impoundment in Florida. Impounding altered the hydrology and soil chemistry of the site. In 1997, we established a factorial experiment along a tree-height gradient with three zones, i.e., fringe, transition, dwarf, and three fertilizer treatment levels, i.e., nitrogen (N), phosphorus (P), control, in Mosquito Impoundment 23 on the eastern side of Indian River. Transects traversed the forest perpendicular to the shoreline, from a Rhizophora mangle-dominated fringe through an Avicennia germinans stand of intermediate height, and into a scrub or dwarf stand of A. germinans in the hinterland. Growth rates increased significantly in response to N fertilization. Our growth data indicated that this site is N-limited along the tree-height gradient. After 2 years of N addition, dwarf trees resembled vigorously growing saplings. Addition of N also affected internal dynamics of N and P and caused increases in rates of photosynthesis. These findings contrast with results for a R. mangle-dominated forest in Belize where the fringe is N-limited, but the dwarf zone is P-limited and the transition zone is co-limited by N and P. This study demonstrated that patterns of nutrient limitation in mangrove ecosystems are complex, that not all processes respond similarly to the same nutrient, and that similar habitats are not limited by the same nutrient when different mangrove forests are compared.

Avicennia↗
PubMed2003

An examination of a compensatory relationship between food limitation and predation in semi-domestic reindeer.

A central issue in ecology is to what extent food limitation and predation affect animal populations. We studied how survival and reproductive success was related to the female's size in a population of semi-domesticated reindeer during 2 years where there was a large difference in snowfall during winter. The females were kept within a predator-free enclosure for about 5 weeks during the calving period and thereafter released to their natural summer pastures. Small females were more likely to fail to reproduce and they produced smaller calves than large females. Additionally, small females were more likely to loose their calves due to starvation within the predator-free enclosure and to predators outside the enclosure. Food limitation during the harsh winter appeared to be the major cause of deaths. However, food limitation interacted with predation and led to high calf losses when the females experienced low food availability during the harsh winter. In contrast, predators killed no calves after the mild winter. Apparently, the interaction between predation and food limitation is due to small females favouring their own growth and survival over calf production in summers following harsh winters with food shortage. Our results indicate that a compensatory relationship exists between mortality due food limitation and predation. Thus, the impact of calf predation on reindeer demography and population dynamics may be limited.

Animals↗
PubMed2006

Consequences of nitrogen and phosphorus limitation for the performance of two planthoppers with divergent life-history strategies.

Phytophagous insects have a much higher nitrogen and phosphorus content than their host plants, an elemental mismatch that places inherent constraints on meeting nutritional requirements. Although nitrogen limitation is well documented in insect herbivores, phosphorus limitation is poorly studied. Using factorial experiments in the laboratory and field, in which levels of soil nitrogen and phosphorus were manipulated, we studied the relative consequences of macronutrient limitation for two herbivores, namely the phloem-feeding planthoppers Prokelisia dolus and P. marginata. These planthoppers inhabit the salt marshes of North America where large stands of their Spartina host plant are found. Notably, these congeners differ in their dispersal abilities; P. marginata is dispersive whereas P. dolus is sedentary. Both nitrogen and phosphorus subsidies enhanced the nitrogen and phosphorus content of Spartina. When P. dolus and P. marginata were raised on plants with an enriched nitrogen signature, they exhibited greater survival, grew to a larger size, developed more rapidly, and achieved higher densities than on nitrogen-deficient plants. However, P. marginata experienced greater fitness penalties than P. dolus on nitrogen-deficient plants. Phosphorus limitation and associated fitness penalties were not as severe as nitrogen limitation for P. marginata, and were not detected in P. dolus. The tempered response of P. dolus to N- and P-deficient Spartina is probably due to its greater investment in feeding musculature and hence ability to compensate for nutrient deficiencies with increased ingestion. To cope with deteriorating plant quality, P. dolus employs compensatory feeding, whereas P. marginata disperses to higher quality Spartina. When its option of dispersal is eliminated and P. marginata is confined on nutrient-deficient plants, its performance is drastically reduced compared with P. dolus. This research highlights the importance of interfacing herbivore life-history strategies with ecological stoichiometry in order to interpret the consequences of macronutrient limitation on herbivore performance and population dynamics.

Animals↗
PubMed2005

Psychological and physical sequelae of intimate partner violence among women with limitations in their activities of daily living.

OBJECTIVE: To compare the psychological and physical sequelae of physical/sexual intimate partner violence in women with and without activity limitations. METHODS: We analyzed data from the Canadian 1999 General Social Survey. We included women reporting intimate partner violence in the previous 5 years (n = 897). RESULTS: As a result of the violence, women with activity limitations were significantly more likely to feel ashamed/guilty (21.7 vs. 14.5%), depression/anxiety (31.5 vs. 19.8%), fearful (43.0 vs. 33.0%), lowered self-esteem (35.2 vs. 21.1%), increased caution/awareness (20.3 vs. 10.9%), and problems relating to men (16.4 vs. 5.4%). Significantly more women with activity limitations reported physical injury from violence (57.0 vs. 36.6%) and having to take time off from everyday activities (42.1 vs. 30.3%). Women with activity limitations had higher medication use for sleeping problems (OR = 3.17, 95% CI = 1.36, 5.73), anxiety (OR = 3.29, 95% CI = 1.75, 6.19) and depression (OR = 2.63, 95% CI = 1.41, 4.90). CONCLUSION: Results suggest an additive effect between intimate partner violence and activity limitations that adds disproportionately to the burden of health for women with activity limitations.

Activities of Daily Living↗
PubMed2006

Growth rate and nutrient limitation affect the transport of Rhodococcus sp. strain DN22 through sand.

Rhodococcus strain DN22 grows on the nitramine explosive RDX as a sole nitrogen source, and is potentially useful for bioremediation of explosives-contaminated soil. In order for strain DN22 to be effectively applied in situ, inoculum cells must reach zones of RDX contamination via passive transport, a process that is difficult to predict at field-scale. We examined the effect of growth conditions on the transport of DN22 cells through sand columns, using chemostat-grown cultures. Strain DN22 formed smaller coccoid cells at low dilution rate (0.02 h(-1)) and larger rods at high dilution rate (0.1 h(-1)). Under all nutrient limitation conditions studied, smaller cells grown at low dilution rate were retained more strongly by sand columns than larger cells grown at high dilution rate. At a dilution rate of 0.05, cells from nitrate-limited cultures were retained more strongly than cells from RDX-limited or succinate-limited cultures. Breakthrough concentrations (C/C (0)) from sand columns ranged from 0.04 (nitrate-limited, D=0.02 h(-1)) to 0.98 (succinate-limited, D=0.1 h(-1)). The observed strong effect of culture conditions on transport of DN22 cells emphasizes the importance of physiology studies in guiding the development of bioremediation technologies.

Biodegradation, Environmental↗
PubMed1995

Impact of the 65 mph speed limit on accidents, deaths, and injuries in Illinois.

At the end of April 1987, Illinois raised the speed limit from 55 to 65 mph on rural interstates and limited-access highways. This paper examines the effects of this change. It applies ARIMA techniques to a monthly time series of accidents, injuries, and fatalities dating from five years before the limit increase to four years after. Two types of rural highways are examined: those where the speed limit was raised and those where it remained at 55 mph. The impact of higher limits on mean speeds, speed variance, traffic diversion, traffic generation, speed spillover, and issues of benefits and costs are considered. The findings suggest the higher limit led to 300 additional accidents per month in rural Illinois, with associated increases in deaths and injuries. This impact was apparent on both 65 and 55 mph roads. There is some evidence of traffic diversion from 55 to 65 mph highways plus traffic generation and speed spillover.

Accidents, Traffic↗
PubMed1986

Effects of the limiting symptom on the achievement of maximal oxygen consumption in patients with coronary artery disease.

This study was conducted to determine if the limiting symptom in patients with coronary artery disease (CAD) influenced the pattern of oxygen consumption (VO2) over the final 90 seconds of a maximal exercise test. The pattern was classified according to the presence or absence of a plateau. Twenty-six normal persons and 55 patients with CAD were studied. They rated the severity of fatigue, dyspnea and angina at end exercise using the Borg scale and designated which symptom was the limiting factor. A plateau of VO2 over the final 90 seconds of exercise was observed in 77% of normal subjects and patients with CAD. Eighty percent of patients limited by angina achieved a plateau. In normal subjects and patients with CAD, peak VO2 was more reproducible than the pattern of VO2 over the final 90 seconds of exercise. There were no differences in the cardiac responses to exercise at maximal effort between patients who achieved a plateau of VO2 and those who did not. These results indicate that the limiting symptom of exercise, even angina pectoris, does not influence the ability to exercise maximally. Therefore, the peak value of VO2 during symptom-limited treadmill exercise is a valid measure of maximal cardiovascular capacity irrespective of the limiting symptom or the pattern of VO2 in the final 90 seconds of exercise.

Adult↗