Biomedical subjects

B D Maxwell

Publications and source records attributed to B D Maxwell.

7 recordsLinked to original sources

PubMed2003

Chronic hypertension in pregnancy.

Hypertension is the most common medical disorder during pregnancy. Chronic hypertension is a serious medical complication in pregnancy with increased maternal and perinatal morbidity and mortality. Those who develop uncontrolled severe hypertension, those with target organ damage, and those who are poorly compliant with prenatal visits are at high risk for poor perinatal outcome. Maternal complications include abruptio placenta, stroke, and superimposed pre-eclampsia. Fetal complications include prematurity, low birth weight, and perinatal death. Careful antepartum, intrapartum and postpartum management of women with high-risk chronic hypertension in pregnancies may reduce morbidity and mortality.

Abruptio Placentae↗

PubMed2000

The necessity of both anorectal and vaginal cultures for group B streptococcus screening during pregnancy.

BACKGROUND: Group B streptococcus (GBS) sepsis affects approximately 2 of every 1000 newborns. In an effort to decrease the incidence of neonatal GBS infection, the Centers for Disease Control and Prevention have established guidelines for screening and treatment during pregnancy. One strategy includes obtaining both vaginal and anorectal GBS cultures, then treating patients whose cultures are positive. Many of our patients are reluctant to undergo anorectal cultures. We conducted a study to determine whether performing cultures of both the vagina and anorectum would change patient management. METHODS: We obtained vaginal and anorectal GBS cultures from 222 consecutive patients at 35 to 37 weeks' gestation. RESULTS: Fifty-four patients (24.3%) had positive GBS cultures. Of those women, 10 (18.5%) had negative vaginal but positive rectal cultures. Thus, nearly one fifth of the patients with GBS colonization would not have received intrapartum antibiotics if only vaginal cultures had been performed. CONCLUSIONS: Health care providers caring for pregnant patients should consider obtaining both vaginal and anorectal cultures when screening for Group B streptococcus.

Cell Culture Techniques↗

PubMed1985

Alterations in breast morphology consequent to a 21-day bust developer program.

Normal menstruating females, 19 to 32 years of age, were randomly assigned to either a control (C; N = 17) or an experimental (E; N = 17) group to determine alterations in breast size, shape, and volume consequent to a 21-day bust development program (BDP) using a commercial exercise device as specified by the manufacturer. E and C groups were evaluated on 2 consecutive d prior to initiating the BDP to establish reliability of the test procedures and again at the end of the BDP, 27 to 29 d following the initial measures. Anthropometric measures included the following girths: shoulder, chest, bust with and without brassiere, abdomen, deltoid, and flexed biceps. Breast photography included two 35-mm photographs each from the side and front views, in both full inspiration and full expiration, with the subject position carefully standardized. A total of 10 measurements, corrected for perspective error, were obtained from these photographs. Breast volume was measured using a water displacement technique, with three trials for each breast. Repeated measures analysis of variance procedures indicated no significant differences consequent to the BDP for any of the variables assessed, with the exception of a small decrease in shoulder girth in both E and C and a small decrease in left breast volume in E. It was concluded that the use of a commercial exercise device with a specific BDP does not result in changes in breast size, shape, or volume.

Adult↗

PubMed1982

Relationship between muscle QO2 and fatigue during repeated isokinetic contractions.

The percent slow-twitch fibers (%ST) of the vastus lateralis muscle and selected indicators of maximum aerobic power (QO2, VO2 max, and leg extensor VO2 max) were compared with the rate of fatigue development during 45 s of repeated maximum isokinetic leg extension-flexion contractions (180 degrees/s) on 13 males. Subjects with muscle respiratory capacities (QO2) above the mean (2,472 microliter O2 X h-1 X g-1) displayed a significantly slower rate of fatigue development than those subjects with QO2 values below the mean. In addition, indicators of maximum aerobic power were correlated with the percent of maximum power and power/ml fat-free thigh volume at 5, 15, 30, and 45 s during the fatigue test. The correlations increased progressively during the fatigue test and became significant at 45 s. This trend was not observed when the %ST fibers were compared with the percent of maximum power and power/ml fat-free thigh volume at these time intervals. These data suggest that 1) the muscle tissue's capacity for aerobic metabolism influences the rate of fatigue development even during a strenuous short-term isokinetic exercise task, and 2) factors other than fiber type may interact to confound the prediction of fiber type by noninvasive means.

Adolescent↗

PubMed1981

Isokinetic contractile properties of the quadriceps with relation to fiber type.

Fifteen subjects were assigned to three groups on the basis of the proportion of fast-twitch fibers (% FT) in their vastus lateralis muscles. Torque production per unit of fat free thigh volume was then determined during knee extension on an isokinetic dynamometer at 60, 120, 180, 240, and 300 degrees . s-1. Maximal isometric force was also obtained at 65 degrees from horizontal. Subjects with predominantly fast twitch muscle fibers demonstrated significantly greater peak power, rate of power production and work than subjects with predominantly slow twitch fibers at all but the lowest velocity of 60 degrees . s-1. Mean peak power for all subjects occurred at approximately 30% of maximal knee extension velocity (210 degrees x s-1) and 34% of maximal voluntary isometric contraction. When work, peak power and rate of power production were correlated with % FT fibers, then the highest correlations of 0.69, 0.57, and 0.73 respectively, all occurred at 180 degrees . s-1. These observations suggest that: 1) the torque-velocity, power-velocity relationship of the quadriceps is similar to the force-velocity, power-velocity relation found for excised muscle, 2) when using the knee extension exercise for the prediction of muscle fiber composition of the quadriceps the most appropriate speed for testing appears to be 80 degrees . s-1.

Adult↗

PubMed1980

Skeletal muscle determinants of maximum aerobic power in man.

The interrelationship between whole body maximum O2 uptake capacity (VO2max), skeletal muscle respiratory capacity, and muscle fiber type were examined in 20 physically active men. The capacity of homogenates of vastus lateralis muscle biopsy specimes to oxidize pyruvate was significantly related to VO2max (r = 0.81). Correlations of 0.75 and 0.74 were found between % slow twitch fibers (%ST) and VO2max, and between %ST fibers and muscle respiratory capacity, respectively (P less than 0.01). Multiple correlation analysis (R = 0.85) indicated that 72% (R2 = 0.72) of the variance in VO2max could be accounted for by the combined effect of muscle respiratory capacity and the %ST fibers. When the %ST fibers was correlated with VO2max, with the effect of respiratory capacity statistically removed, the relationship became insignificant (r = 0.38). These data suggest that muscle respiratory capacity plays an important role in determining VO2max, and that the relationship between %ST fibers and VO2max is due primarily to the high oxidative capacity of this muscle fiber type.

Adolescent↗

PubMedDate not supplied

Two recessive gene inheritance for triallate resistance in Avena fatua L.

Extensive use of the preemergence herbicide triallate over the last three decades has selected for resistant (R) Avena fatua L. populations in several areas of the United States and Canada. R plants are also cross-resistant to the unrelated pyrazolium herbicide difenzoquat. We made reciprocal crosses between inbred R and susceptible (S) lines to determine the genetic basis of triallate resistance. Seeds from parental lines and F(2) populations were treated with soil applications of 0.275, 0.55, or 1.1 kg/ha triallate in the greenhouse and plant heights recorded after 37 days. Surviving F(2) plants were selfed and the resulting F(3) families were screened with 1.1 kg/ha triallate. In the F(2) populations, assortment of S and R phenotypes fit a 15:1 segregation ratio, suggesting that resistance was controlled by the two independently segregating recessive genes TRR1 and TRR2. None of the 912 F(3) progeny from 51 R F(2) individuals was susceptible to triallate treatment, further supporting a two-gene mode of inheritance. There was a possible maternal effect on susceptibility at the highest triallate rate tested.

Avena↗