Effect of intake on fasting heat production, respiratory quotient and plasma metabolites measured using the washed rumen technique.

The objective was to investigate the effect of intake before fasting on concentrations of metabolites and hormones, respiratory quotient (RQ) and fasting heat production (HP) using the washed rumen technique and to compare these values with those from the fed state. Six Holstein steers (360±22 kg) were maintained at 21°C and fed three different energy intakes within a replicated 3×3 Latin square design with 21-day periods. Steers were fed alfalfa cubes to provide 1.0, 1.5 and 2.0×NEm during 19 days of each experimental period. Steers were placed in individual metabolism stalls fitted with indirect calorimetry head-boxes on day 20 of each experimental period (FED steers) and fed their normal meal. On day 21 of each period the reticulorumen was emptied, washed and refilled with ruminal buffer (NaCl=96; NaHCO3=24; KHCO3=30; K2HPO4=2; CaCl2=1.5; MgCl2=1.5 mmol/kg of buffer) aerated with 75% N2 and 25% CO2 before introduction to the rumen (steers were not fed; WASHED steers). Each gas exchange was measured over 24 h. HP for 1.0, 1.5 and 2.0×NEm were 479, 597 and 714 kJ/daykg0.75 (s.e.m. =16), respectively. The plateau RQ was 0.756, 0.824 and 0.860 for the 1.0, 1.5 and 2.0×NEm intakes for the FED steers, respectively. After rumen washing, fasting HP was 331, 359 and 400 kJ/daykg0.75 (s.e.m.=13) for 1.0, 1.5, and 2.0×NEm intakes before fasting, respectively. The RQ for WASHED rumen steers was 0.717, 0.710 and 0.719, respectively. Cortisol and ß-hydroxybutyrate concentrations in WASHED rumen steers did not exceed threshold levels for severe energy deficit and stress as can be induced from prolonged fasting. This study demonstrates that a fasting state can be emulated using the washed rumen technique, minimizing the time required as opposed to traditional fasting methodologies, without causing a severe energy deficit and stress.

Comparison of three different models to represent the wrist during wheelchair propulsion.

Due to the high incidence of secondary wrist injury among manual wheelchair users, recent emphasis has been placed on the investigation of wheelchair propulsion biomechanics. Accurate representation of wrist activity during wheelchair propulsion may help to elucidate the mechanisms contributing to the development of wrist injuries. Unfortunately, no consensual wrist biomechanical model has been established. In order to determine if different methodologies obtain similar results, this investigation created and compared three different wrist models: 1) a fixed joint center placed between the styloids (midstyloid joint center); 2) a joint center with 2 degrees of freedom computed from de Leva's joint center data; and 3) a floating joint center. Results indicate that wrist flexion and extension angles are highly consistent between models, however, radial and ulnar deviation angles vary considerably. Mean maximum right flexion angles were found to be 3.5 degrees, 2.2 degrees, and 5.0 degrees for the midstyloid, de Leva, and floating joint center models, respectively. Extension angles were 22.3 degrees, 23.6 degrees, and 23.6 degrees, respectively. Mean maximum right radial deviation angles for the midstyloid, de Leva, and floating joint center models were 26.0 degrees, 26.9 degrees, and 45.1 degrees, respectively, and ulnar deviation angles were found to be 30.5 degrees, 38.8 degrees, and 10.2 degrees, respectively. This information is useful when comparing kinematic studies and further supports the need for consensual methodology.

Pregnancy and infant health: progress toward the 1990 objectives.

Assuring all infants a healthy start in life and enhancing the health of their mothers are goals of the Public Health Service's health promotion and disease prevention initiative. The 13 priority objectives selected for the pregnancy and infant health area of the initiative focus on lowering infant, neonatal, and perinatal mortality rates, reducing the number of low-birth-weight infants, improving the health care of pregnant women and infants through regionalized perinatal care systems and comprehensive primary care services, encouraging early prenatal care and healthy lifestyles in pregnancy, and targeting the factors and populations associated with health risk. Although considerable progress has been made in this century in lowering the infant mortality rate, infants continue to die at a higher rate than members of any other age category under 60 years, and black infants die at almost twice the rate of white infants. To lower these high mortality rates, the private, public, and voluntary sectors have cooperated in new approaches to perinatal and infant health that have already produced some encouraging results. Recent data, for example, indicate that the priority objective of universal screening of newborns for treatable metabolic disorders has already been achieved and that the target for neonatal and infant mortality rates could be reached earlier than 1990. Substantial challenges, however, lie ahead if the current racial and ethnic differentials evident in the rates for prenatal care registration, low-birth-weight babies, and maternal and infant mortality are to be eliminated.

Perceptions of risks of smoking and heavy drinking during pregnancy: 1985 NHIS findings.

As part of the Health Promotion and Disease Prevention Questionnaire administered in the 1985 National Health Interview Survey, nearly 20,000 respondents ages 18-44 answered questions about their awareness of the risks of smoking and heavy drinking during pregnancy. In reference to smoking, interviewers asked about miscarriage, stillbirth, prematurity, and low birth weight; in reference to heavy drinking, they asked about miscarriage, mental retardation, low birth weight, and birth defects, as well as fetal alcohol syndrome. For each of these adverse outcomes, a majority of subjects acknowledged increased risk because of smoking or heavy drinking during pregnancy. The range was 66-80 percent of respondents for the four questions on smoking, with the perceived association to smoking strongest for low birth weight. Approximately 84 percent of respondents associated heavy drinking with increased risk for each of the suggested pregnancy outcomes. Smoking seemed to be perceived to pose a lesser risk to pregnancy than heavy drinking. This relative lack of awareness of the pregnancy risks of smoking was more apparent among respondents with less education and more pronounced among blacks than whites. Women were more likely than men to express some opinion on these pregnancy-related questions and were more cognizant than men of the risks. On this limited survey, Americans ages 18-44 were not very knowledgeable about fetal alcohol syndrome. Among the 55 percent who had heard of fetal alcohol syndrome, fewer than one in four correctly identified it as a set of birth defects when offered three possible definitions. It will be interesting to correlate responses to these "knowledge" questions with NHIS data still forthcoming on reported actual smoking and drinking behavior among women respondents who were recently pregnant.

Using linked birth and infant death files for program planning and evaluation: NIMS workshop lessons.

Health planners should base program decisions on the best information available. Combining information from different sources can be valuable in identifying problems--the essential first step in program planning. To facilitate this process, a workshop was conducted during the National Infant Mortality Surveillance Conference in Atlanta, GA. Maternal and child health directors explored the use of linked birth and infant death data for program planning and evaluation. Linked birth and infant death certificate files permit evaluation of infant mortality by birth weight and other infant and maternal characteristics, thus providing more detailed information than birth or death certificates alone. An assessment of the birth weight distribution of live births, birth weight specific-mortality risks, distribution of deaths by birth weight, and birth weight-specific causes of death can help identify problems in the childbearing population and with the delivery of health services. Once the infant health problems are defined clearly, the selection and delivery of services can be better targeted and evaluated for the reduction of these problems.

Racial differences in pregnancy outcomes.

Black mothers in the United States are twice as likely as their white counterparts to experience a wide variety of adverse pregnancy outcomes, including prematurity, low birth weight, and infant and fetal death. Although blacks have higher proportions of births with maternal risk factors such as young age, high birth order, low education, and unmarried mothers, these differences do not account for their higher rates of adverse outcomes; the reasons for the excess remain largely unknown. To develop effective interventions to reduce the racial disparities in pregnancy outcome, we must further our understanding of the mechanisms underlying premature onset of labor and intrauterine growth.

An autoregressive modeling approach to analyzing wheelchair propulsion forces.

Biomechanical signals collected during wheelchair propulsion are often analyzed by computing averages and/or peak values over several strokes. Due to the complex nature of the signals, this type of analysis may not be specific to identifying factors that may predispose a wheelchair user to joint pain/injury. Hence, a new technique is introduced that uses a system identification approach, autoregressive (AR) modeling, to analyze wheelchair propulsion force waveforms. In this application an AR method was used to create a model force waveform based on current and past values of digital pushrim force data. The feasibility of the AR modeling method over point-wise methods to detect asymmetry among force waveforms was tested with a group of 20 wheelchair users. Subjects propelled at a constant 0.9 m/s on a roller system during which 20 s of force data were collected from the SMART(Wheel)s, force and torque sensing pushrims. Both methods showed that the wheelchair users as a group propelled evenly, however, individual analysis using the AR model error estimates indicated that twenty-five percent demonstrated significant asymmetry in their force waveforms. If only point-wise means and variances of the applied bilateral forces were considered, most subjects would have appeared symmetrical. Thus, the AR modeling approach is more sensitive to detecting anomalies in propulsion technique.

Serving women in need: nurse-midwifery practice in the United States.

OBJECTIVE: Nurse-midwifery practices in the United States were examined to study the relationship between certified nurse-midwives' (CNMs) demographic, work setting, and practice characteristics in terms of clientele, practice size, and practice type. Factors that might influence the ability of CNMs to serve populations at risk for poor outcomes were given particular attention. METHODOLOGY: A total of 2,405 responses to a 1998 mailed survey of 6,365 nurse-midwives ever-certified by the American College of Nurse-Midwives were analyzed. RESULTS: Study results indicated that CNMs continue to serve a population who are, based on a social risk profile, disproportionately at risk for poor pregnancy outcomes, including women who are uninsured (16%), immigrant (27%), adolescent (29%), and women of color (50%). It was also found that clientele varied according to practice settings: CNMs working in non-hospital, nonprofit settings served a clientele that was 65% nonwhite, 44% immigrant, 40% adolescent, and 29% uninsured; these CNMs received 61% of their client payments from Medicaid. CNMs working in private offices or for managed care organizations were less likely to serve women with these characteristics. CONCLUSION: Study results, taken in conjunction with research that documents the safety of nurse-midwifery practice, reinforce policy recommendations that support expanded access to nurse-midwifery services. Findings also indicate a need for further research in the areas of CNM workload and productivity in managed care settings and the association between CNM race and ethnicity and the race and ethnicity of their clients.

Adult attachment: what are the underlying dimensions?

Using a community sample of 115 young adults, this study applied a range of statistical techniques to five measures of adult attachment to gain a better understanding of what they assess. First, we determined comparability of measures, using both categorical and dimensional approaches to model the association. Agreement among classifications was modest. Next, we examined the relation of attachment classifications and attachment measure subscale scores to criterion variables (i.e. dyadic adjustment, interpersonal sensitivity and severity of psychiatric symptoms). Classification predicted severity of psychological symptoms better than it predicted other measures of adjustment. Finally, using a principal components analysis, we mapped the relationship among underlying constructs, the subscales of the five measures and three criterion measures of psychological adjustment. We discuss our findings from the perspective of underlying constructs of attachment insecurity and strategy for coping with insecurity in relationships, noting implications for further research.

Alteration of fasting heat production during fescue toxicosis in Holstein steers.

This study was designed to examine alteration of fasting heat production (FHP) during fescue toxicosis. Six ruminally cannulated Holstein steers (BW = 348 ± 13 kg) were BW-matched into pairs and used in a 2 period crossover design experiment. Each period consisted of 2 temperature segments, one each at 22 and 30°C. During each period, 1 steer per pair was ruminally dosed twice daily with 0.5 kg of ground endophyte-infected fescue seed (E+) and the other with ground endophyte-free fescue seed (E-) for 7 d. Steers on E- treatment were pair-fed to E+ steers offered alfalfa cubes at 1.5 × NEm. On d 8 of each segment, steers were moved to individual metabolism stalls fitted with indirect calorimetry head boxes. Ruminal contents were removed, weighed, and subsampled for DM determinations. The reticulorumen was washed and filled with a buffer (NaCl = 96; NaHCO3 = 24; KHCO3 = 30; K2HPO4 = 2; CaCl2 = 1.5; MgCl2 = 1.5 mmol·kg buffer(-1)) that was gassed with a 75% N2 and 25% CO2 mixture before rumen incubation. During buffer incubation, an E+ or E- fescue seed extract was added at 12 h intervals to maintain treatment presentation to the animal. After a 12-h wait, heart rate, O2 consumption, CO2 production, and urinary output were recorded for 16 h. There was no difference (P = 0.931) in DMI/kg(0.75) between endophyte treatments by design; however, intake decreased (P = 0.004) at 30°C. Increased temperature had no effect (P > 0.10) on other measurements and there were no significant interactions (P > 0.11) of temperature and endophyte treatment. Heart rate was unaffected by fescue treatment or environmental temperature. Percent DM of ruminal contents as well as total rumen DM/kg(0.75) was increased (P < 0.0001) in E+ steers. Respiratory quotient was elevated (P = 0.02) in E+ steers. Oxygen consumption decreased (P = 0.04) and CO2 production tended to be reduced (P = 0.07) during E+ treatment. Calculated FHP (kcal/kg BW(0.75)) was also less (P = 0.006) in steers receiving E+ treatment. These data suggest that consumption of endophyte-infected tall fescue by cattle results in a reduction in basal metabolic rate.

Evaluation of a rapid determination of fasting heat production and respiratory quotient in Holstein steers using the washed rumen technique.

The objective of this study was to validate use of the washed rumen (WR) technique for rapid measurement of fasting heat production (HP) and respiratory quotient (RQ). Sixteen Holstein steers were divided into 2 groups of 8 for a comparison of measurements made during feeding (both groups; 16 steers) and fasting (8 steers; BW = 237 ± 17 kg) and using the WR model (8 steers; BW = 322 ± 30 kg). Steers were maintained in a controlled temperature (21°C) environment and treated as follows: 10 d diet adaptation, 1 d measurement of respiratory gases at 1.5 × NEm (Fed state; all steers d 11), 1 d measurement of respiratory gases under fasting conditions (Fasted; 8 steers d 12) or using the WR technique (8 steers d 12), and 7 d to monitor the reestablishment of intake. Steers were offered alfalfa cubes top-dressed with a mineral premix at 1.5 × NEm. Using an indwelling probe, core temperature (CT) and heart rate (HR) were monitored continuously during the days respiratory gases were measured. For fasting measurements using the WR technique, the reticulorumen was washed and refilled with ruminal buffer (NaCl = 96, NaHCO3 = 24, KHCO3 = 30, K2HPO4 = 2, CaCl2 = 1.5, and MgCl2 = 1.5 mmol/kg of buffer) with Cr-EDTA aerated with 75% N2 and 25% CO2 before introduction to the rumen. Mean hourly CT, RQ, and daily HP between Fasted steers and WR steers were decreased for the WR steers on average from 8 to 24 h after removal of rumen contents (P = 0.049, P < 0.001, and P = 0.076, respectively). Fitting RQ data obtained during fasting to a 1-phase decay equation showed that plateau was achieved at 0.756 ± 0.003 and 0.719 ± 0.003 and time to plateau was 9 and 8 h for Fasted and WR steers, respectively. Mean RQ after WR were 0.778, 0.732, and 0.726 (SEM = 0.003) for time segments 0 to 8 h, 9 to 16 h, and 17 to 24 h, respectively. Mean fasting HP after WR was 18.8, 16.8, and 16.5 (SEM = 0.51) kJ/(h • kg(0.75)) for time segments 0 to 8 h, 9 to 16 h, and 17 to 24 h, respectively. There were no significant differences in RQ and fasting HP (P = 0.23 and P = 0.81, respectively) between the time segment of 9 to 16 h and 17 to 24 h after rumen washing. In contrast, both RQ and HP differed (P = 0.090 and P = 0.081, respectively) across these same time segments for the Fasted group. Therefore, an accurate measurement of fasting HP can be obtained using a shorter-term measurement with the WR technique. This approach provides an alternative to the traditional 48 h fasting time or measurements made during the third and fourth day after starvation.

Ergot alkaloids from endophyte-infected tall fescue decrease reticuloruminal epithelial blood flow and volatile fatty acid absorption from the washed reticulorumen.

An experiment was conducted to determine if ergot alkaloids affect blood flow to the absorptive surface of the rumen. Steers (n=8) were pair-fed alfalfa cubes and received ground endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum; E+) seed (0.015 mg ergovaline·kg BW(-1)·d(-1)) or endophyte-free tall fescue (E-) seed via the rumen cannula 2x daily for 7 d at thermoneutral (TN; 22°C) and heat stress (HS; 32°C) conditions. On d 8, the rumen was emptied and rinsed. A buffer containing VFA was incubated in the following sequence: control (CON), 15 µg ergovaline·kg BW(-1) (1×EXT) from a tall fescue seed extract, and 45 µg ergovaline·kg BW(-1) (3×EXT). For each buffer treatment there were two 30-min incubations: a 30-min incubation of a treatment buffer with no sampling followed by an incubation of an identical sampling buffer with the addition of Cr-EDTA and deuterium oxide (D2O). Epithelial blood flow was calculated as ruminal clearance of D2O corrected for influx of physiological water and liquid outflow. Feed intake decreased with dosing E+ seed at HS but not at thermoneutral conditions (TN; P<0.02). Dosing E+ seed decreased serum prolactin (P<0.005) at TN. At HS, prolactin decreased in both groups over the 8-d experiment (P<0.0001), but there was no difference in E+ and E- steers (P=0.33). There was a seed treatment×buffer treatment interaction at TN (P=0.038), indicating that E+ seed treatment decreased reticuloruminal epithelial blood flow at TN during the CON incubation, but the two groups of steers were not different during 1×EXT and 3×EXT (P>0.05). Inclusion of the extract in the buffer caused at least a 50% reduction in epithelial blood flow at TN (P=0.004), but there was no difference between 1×EXT and 3×EXT. There was a seed × buffer treatment interaction at HS (P=0.005), indicating that the reduction of blood flow induced by incubating the extract was larger for steers receiving E- seed than E+ seed. Volatile fatty acid flux was reduced during the 1×EXT and 3×EXT treatments (P<0.01). An additional experiment was conducted to determine the effect of time on blood flow and VFA flux because buffer sequence could not be randomized. Time either increased (P=0.05) or did not affect blood flow (P=0.18) or VFA flux (P>0.80), indicating that observed differences are due to the presence of ergot alkaloids in the rumen. A decrease in VFA absorption could contribute to the signs of fescue toxicosis including depressed growth and performance.

Evaluation of a ruminally dosed tall fescue seed extract as a model for fescue toxicosis in steers.

Tall fescue (Lolium arundinaceum) toxicosis research is often complicated by a reduction in intake of infected forage or seed, making treatment comparisons difficult. This study was conducted to develop a fescue toxicosis model that would allow for variations in DMI without altering the quantity of alkaloids consumed over the course of the experiment. Ground tall fescue seed and a tall fescue seed extract were used in two 2-period crossover experiments to determine the effectiveness of ruminal dosing of a tall fescue seed extract to induce fescue toxicosis. This experiment used 4 growing Holstein steers (BW = 337 ± 24 kg) surgically fitted with ruminal cannulas. Steers were maintained on a diet of endophyte-free fescue hay fed ad libitum throughout the experiment. Endophyte-infected (E+; 4.1 mg/kg of ergovaline) and uninfected (E-; 0.0 mg/kg of ergovaline) KY-31 tall fescue seed was ground and dosed or extracted with ethanol, concentrated, and lyophilized before ruminal dosing. Ergovaline concentration of the final extract was 102 mg/kg. Animals were given a minimum of a 3-wk washout period between treatments. Physiological indicators were measured over 7 d at 22°C (d 1 to 3) and 32°C (d 4 to 7) during both seed and extract dosing. Seed and extract E+ dosing reduced serum prolactin concentrations such that they were not different from zero (P < 0.10). Treatment with E+ reduced feed intake (P < 0.05) and heart rate (P < 0.001), and increased respiration rate (P < 0.01) and core temperature (P < 0.05) during both seed and extract dosing. Increasing environmental temperature from 22 to 32°C reduced total intake (P < 0.05) and increased core temperature (P < 0.001) and respiration rate (P < 0.001) during both seed and extract dosing. Diastolic blood pressure tended (P < 0.09) to be increased during E+ extract dosing and reduced during heat stress. These physiological alterations are consistent with those reported for cattle grazing or consuming seed from endophyte-infected tall fescue. These data indicate that a ruminally dosed ethanol extract of tall fescue seed is efficacious in inducing fescue toxicosis in cattle.

Minicolumn detection method applied to almonds: collaborative study.

The minicolumn screening method for aflatoxins was collaboratively tested on naturally contaminated almonds. The nuts were extracted, and the extract was cleaned up and applied to a Velasco-type minicolumn. This permits the detection of total aflatoxins (B1, B2, G1, G2) as a fluorescent band on the Florisil layer of the column. The results of 20 collaborators are presented. Samples containing 0, 2, 5, 10, and 25 ng aflatoxin/g were analyzed. Ninety-six per cent of the samples containing 5--25 ng total aflatoxins/g and 83% of the negative samples were correctly identified. The method has been adopted as official first action for detection of total aflatoxin levels of greater than or equal to 5 ng/g.

Manual wheelchair pushrim biomechanics and axle position.

OBJECTIVE: The biomechanics of wheelchair propulsion have been linked to upper extremity injury. Specifically, prior studies have correlated increased median nerve dysfunction with increasing propulsion frequency and a higher rate of rise of the resultant, or total, pushrim force. Despite this link, there is little research on the effect of wheelchair setup on propulsion biomechanics. The objective of this study was to determine the effect of rear axle position relative to the shoulder on pushrim biomechanics. DESIGN: Case series. SETTING: Biomechanics laboratory. PARTICIPANTS: Forty individuals with paraplegia who use manual wheelchairs for mobility. INTERVENTION: Subjects propelled their own wheelchairs on a dynamometer at two different steady-state speeds and going from a dead stop to maximum speed. Bilateral biomechanical data were obtained using a force- and moment-sensing pushrim and a motion analysis system. MAIN OUTCOME MEASURES: Position of the axle relative to the shoulder at rest both horizontal (XPOS) and vertical (YPOS), and pushrim biomechanical variables including frequency of propulsion, peak and rate of rise of the resultant force, planar moment, and push angle. Partial correlation coefficients between relative axle position and propulsion biomechanics variables were calculated. RESULTS: After controlling for subject characteristics, XPOS was significantly correlated with the frequency of propulsion (p < .01) and the rate of rise of the resultant force (p < .05). In addition, both XPOS and YPOS were significantly correlated with the push angle at multiple speeds (p < .05). CONCLUSION: Specific biomechanical parameters known to correlate with median nerve injuries were found to be related to axle position relative to the shoulder. Providing wheelchair users with adjustable axle position and then fitting the user to the wheelchair can improve propulsion biomechanics and likely reduce the risk of injury.