Biomedical subjects

C R Qualls

Publications and source records attributed to C R Qualls.

35 records · Page 2Linked to original sources

PubMed1997

Digoxin-like immunoreactive substance and sodium-potassium-adenosine triphosphatase inhibition in normal pregnancy: a longitudinal study.

OBJECTIVE: To measure the levels of digoxin-like immunoreactive substance and digitalis-like factor bioactivity as manifested by sodium-potassium-adenosine triphosphatase (ATPase) inhibition throughout pregnancy. METHODS: Serum samples were collected from primigravidas in early (15 +/- 1.8 weeks), mid (26 +/- 1.2 weeks), and late (36 +/- 1.1 weeks) gestation, as well as at 6 +/- 1.1 weeks postpartum (mean +/- standard error). Digoxin-like immunoreactive substance levels were determined by radioimmunoassay and digitalis-like factor bioactivity was determined by inhibition of ATPase. Data were analyzed by means of repeated measures analysis of variance. RESULTS: In 41 women with normal pregnancy outcomes, levels of digoxin-like immunoreactive substance rose progressively and significantly (P < .001) throughout pregnancy and returned to normal levels postpartum. Inhibition of ATPase activity also rose significantly (P < .004), but not as dramatically, during pregnancy and remained elevated 6 weeks postpartum. CONCLUSION: Although digoxin-like immunoreactive substance levels rise in pregnancy, functional digitalis-like factor activity, as manifested by inhibition of ATPase, does not parallel this rise strictly, implying that digoxin-like immunoreactive substance receptors may be reset during normal pregnancy. The enhanced cardiac performance that occurs in normal pregnancy may be mediated in part by increased digitalis-like factor activity.

Adenosine Triphosphatases↗

PubMed1997

A randomized trial of misoprostol and oxytocin for induction of labor: safety and efficacy.

OBJECTIVE: To compare the safety and efficacy of misoprostol and oxytocin for induction of labor. METHODS: One hundred thirty women requiring induction of labor were randomized to receive either intravenous oxytocin or 100 micrograms misoprostol, administered intravaginally every 4 hours until labor was established. RESULTS: Compared with women receiving oxytocin, a greater percentage of women in the misoprostol group had Bishop scores of 3 or less (58 versus 38%, P < .05). Nonetheless, the median induction-to-delivery interval was significantly shorter (585 versus 885 minutes, P < .001) in the misoprostol group. Women in the misoprostol group were more likely to deliver vaginally within 24 hours of the start of induction (77 versus 55%, P < .002). Epidural analgesia was used more frequently in women receiving oxytocin than in those receiving misoprostol (73 versus 50%, P = .025). The total percentage of cesarean deliveries was not significantly different, although the percentage of cesarean deliveries for dystocia was lower in the misoprostol group (8 versus 21%, P = .02). Uterine tachysystole was significantly more common (70 versus 11%, P < .001) and hospital charges significantly less with misoprostol. CONCLUSION: Compared with oxytocin for labor induction, misoprostol results in a shorter induction-to-delivery interval, a reduction in the rate of cesarean delivery for dystocia, and a decreased use of epidural analgesia. Uterine tachysystole is significantly more common with the use of misoprostol.

Adult↗

PubMed1997

Changes in hemodynamics, ventricular remodeling, and ventricular contractility during normal pregnancy: a longitudinal study.

OBJECTIVE: To investigate the hemodynamic changes occurring in normal pregnancy and to see if these changes were associated with an increase in myocardial contractility. METHODS: In a longitudinal study, primigravidas were studied with echocardiography in early (15 +/- 1.8 weeks), mid (26 +/- 1.2 weeks), and late (36 +/- 1.0 weeks) gestation, as well as at 6 weeks postpartum. Cardiac dimensions were measured with two-dimensional and M-mode echocardiography and hemodynamic indices were calculated. All measurements were made with subjects in the left lateral decubitus position. Statistical analysis was performed with repeated measures analysis of variance. RESULTS: Seventy-six women with normal pregnancy outcomes completed all four studies. From the baseline study to late gestation, an increase in cardiac output of 27% (from [mean +/- standard error] 4.2 +/- 0.1 to 5.8 +/- 0.2 L/min, P = .001), and a decrease in total peripheral resistance of 33% (from 1356 +/- 69 to 941 +/- 37 dynes/second cm-5, P = .001) occurred. Over this same time period, left ventricular function, while demonstrating a small and non-significant increase in velocity of circumferential fiber shortening (from 1.25 +/- 0.02 to 1.27 +/- 0.02 cm/second), revealed a 12% decrease in wall stress (from 36.3 +/- 1.0 to 31.9 +/- 1.0 g/cm2, P = .001) and a 13% decrease in the load-independent wall stress to velocity of circumferential fiber shortening ratio (from 30.0 +/- 1.2 to 26.1 +/- 1.0, P = .01), implying enhanced intrinsic myocardial contractility. CONCLUSION: Normal pregnancy is characterized by enhanced myocardial performance.

Adult↗

PubMed1997

"Preeclamptic labs" for evaluating hypertension in pregnancy.

OBJECTIVE: To determine the utility of evaluating coagulation function in patients with chronic hypertension, transient hypertension, preeclampsia, eclampsia and the HELLP syndrome. STUDY DESIGN: We retrospectively reviewed the charts of 244 patients who delivered between March 1992 and March 1994 at the University of New Mexico with a discharge diagnosis of either hypertension, preeclampsia or eclampsia. RESULTS: Nine patients were thrombocytopenic on admission, as defined by a platelet count of < 100,000/mm3. Three of the 244 patients had mild prolongation of the partial thromboplastin time, and none had prolongation of the prothrombin time. Two of the patients with prolongation of the partial thromboplastin time were thrombocytopenic on admission, and the last had elevation of liver enzymes. No patient had clinical evidence of coagulopathy. CONCLUSION: Measurement of the partial thromboplastin time and prothrombin time in the evaluation of preeclampsia/eclampsia can be avoided if the platelet count and liver enzymes are normal. This results in a decrease in hospital charges and no compromise in patient safety.

Cost Savings↗

PubMed1996

Differential tolerance to biological and subjective effects of four closely spaced doses of N,N-dimethyltryptamine in humans.

Tolerance of the behavioral effects of the short-acting, endogenous hallucinogen, N,N-dimethyltryptamine (DMT) is seen inconsistently in animals, and has not been produced in humans. The nature and time course of responses to repetitive, closely spaced administrations of an hallucinogenic dose of DMT were characterized. Thirteen experienced hallucinogen users received intravenous 0.3 mg/kg DMT fumarate, or saline placebo, four times, at 30 min intervals, on 2 separate days, in a randomized, double-blind, design. Tolerance to "psychedelic" subjective effects did not occur according to either clinical interview or Hallucinogen Rating Scale scores. Adrenocorticotropic hormone (ACTH), prolactin, cortisol, and heart rate responses decreased with repeated DMT administration, although blood pressure did not. These data demonstrate the unique properties of DMT relative to other hallucinogens and underscore the differential regulation of the multiple processes mediating the effects of DMT.

Adrenocorticotropic Hormone↗

PubMed1996

Comparison of absorbable uterine staples and traditional hysterotomy during cesarean delivery.

OBJECTIVE: To evaluate the use of the Auto Suture Poly CS-57 disposable surgical stapler to determine if the device offers any advantages over suture closure of the uterus. METHODS: A matched case-control study design was used. Operative time, estimated blood loss, change in hematocrit, incidence of postoperative endometritis, length of stay, and total patient costs were compared. Patients were recruited from a university hospital setting and a private practice. RESULTS: There were 288 patients in the study, 144 in the staple group and 144 matched patients in the standard hysterotomy control group. Patients did not differ in age, parity, gestational age, number of primary or repeat operations, anesthesia, infant weights, or outcomes. Comparing the patients in the staple group and the control group, there was no significant difference in operative time (63.7 +/- 22.9 versus 62.0 +/- 22.3 minutes, staple group versus controls, respectively), estimated blood loss (822 +/- 338 versus 879 +/- 318 mL), change in hematocrit (-5.9 versus -6.5 volume percent), incidence of postoperative endometritis (15 versus 20%), length of stay (4.1 +/-1.3 versus 4.0 +/- 2.2 days), or total cost ($4490 +/- 1544 versus $3997 +/- 1117). Comparing patients operated upon by residents in the university to those operated upon by the private attending physicians, there were no significant differences noted in the above-mentioned variables between stapled and sutured patients. CONCLUSION: Compared with the usual suture technique for cesarean delivery, the uterine stapling device used in this study was not associated with a significant decrease in the incidence of postoperative anemia, infection, length of hospital stay, or cost. This device appears to offer no advantage over traditional hysterotomy and repair.

Case-Control Studies↗

PubMed1996

Postoperative management of cesarean patients: the effect of immediate feeding on the incidence of ileus.

OBJECTIVE: To evaluate the effect of immediate feeding on gastrointestinal function in patients undergoing cesarean delivery. METHODS: A prospective study was conducted in which patients were randomized to one of two groups, either early feeding or delayed feeding, ie, feeding according to the institution's current protocol. Questionnaires were filled out by the subjects on the day of discharge. Fisher exact test was used to compare the two groups with respect to the type of anesthetic used and to compare the incidence of gastrointestinal symptoms. A one-sided exact binomial confidence interval was used to determine the upper bound of the likelihood of paralytic ileus. Logistic regression analysis was used to evaluate the presence of ileus symptoms when controlling for the type of anesthetic used. RESULTS: There were no significant differences between the control and study groups. There was no significant difference in the number of gastrointestinal symptoms between the two groups. The incidence of postoperative paralytic ileus was zero in both the study and control groups. CONCLUSION: Routine early feeding of subjects undergoing cesarean delivery can be implemented without an increase in gastrointestinal symptoms or paralytic ileus.

Anesthesia, Obstetrical↗

PubMed1996

A prospective randomized evaluation of a hygroscopic cervical dilator, Dilapan, in the preinduction ripening of patients undergoing induction of labor.

OBJECTIVE: Our purpose was to investigate the safety and efficacy of a synthetic intracervical hygroscopic dilator, Dilapan (Gynotech, Inc., Middlesex, N.J.), on ripening the cervix before medically indicated induction of labor. STUDY DESIGN: Two hundred forty patients with a Bishop score of < or = 4 were prospectively randomized to receive either preinduction synthetic hygroscopic dilators (n = 112) or no pretreatment (n = 128) before oxytocin induction. RESULTS: Compared with controls, the dilator group exhibited a significant change in median Bishop score, but there was no significant difference in length of labor (dilator 18.8 +/- 12.8 hours vs control 21.7 +/- 14.8 hours) or in the cesarean section rate (dilator 41/112 [36.6%] vs control 49/128 [38.3%]). Relative proportions of nulliparous and multiparous patients, infant weights, and cervical dilation at the time of cesarean section were not significantly different between groups. No adverse maternal or fetal effects could be attributed to use of the device. CONCLUSIONS: Preinduction cervical ripening with hygroscopic dilators does not shorten the length of labor or lower the cesarean section rate in patients undergoing induction of labor.

Abortifacient Agents↗

PubMed1996

Assessment of stimulated and spontaneous adrenocorticotropin secretory dynamics identifies distinct components of cortisol feedback inhibition in healthy humans.

Corticosteroids inhibit ACTH secretion through diverse cellular mechanisms, including direct pituitary and indirect suprapituitary effects. Although exogenous CRH provides a useful assessment of corticotroph function, the suprapituitary component of ACTH regulation has been difficult to assess in humans. Naloxone (NAL) has been reported to stimulate ACTH secretion indirectly through the release of endogenous hypothalamic CRH, suggesting its potential application in the examination of suprapituitary regulation of ACTH secretory dynamics. We sought to examine the inhibitory effects of corticosteroids on kinetic parameters of ACTH secretion, assessed by a deconvolution method, in healthy human subjects. We also sought to directly compare the ACTH responses to serial administration of human CRH and NAL as well as spontaneously occurring ACTH pulses to distinguish pituitary and suprapituitary components of hypothalamic-pituitary-adrenal regulation. Normal healthy subjects (n = 11) received hCRH (0.4 microgram/kg) at 1800 h and then NAL (65 micrograms/kg) at 1930 h, respectively, on 3 separate study days: placebo pretreatment plus CRH/NAL stimulation, metyrapone (MET) pretreatment plus CRH/NAL, or MET alone. Plasma ACTH and serum cortisol were assessed at frequent (every 10 min) intervals during CRH/NAL or placebo infusions (1800-2100 h) on all 3 study days, and deconvolution analysis was performed to determine kinetic parameters of endogenous and stimulated ACTH secretion. Suppression of endogenous cortisol secretion with MET significantly increased both continuous (basal secretion rate) and pulsatile CRH- and NAL-stimulated ACTH bursts (P < 0.05). The increase in total ACTH secreted per burst was related to two distinct effects of cortisol regulating the amplitude (maximum secretion rate) and half-duration (P < 0.05) of secretory bursts. The ACTH responses to CRH and NAL for individual subjects were significantly and positively correlated in both placebo pretreatment plus CRH/NAL stimulation and MET pretreatment plus CRH/NAL studies (P < 0.01). MET administration disproportionately increased the ACTH response to NAL, producing a significant increase (P < 0.01) in the slope of the regression relating ACTH responses to CRH and NAL. The following conclusions were made: 1) endogenous cortisol secretion, even at levels associated with relatively low serum cortisol concentrations, exerts a significant negative feedback effect on both continuous and pulsatile ACTH secretion; 2) cortisol inhibits pulsatile ACTH secretion through distinct regulatory mechanisms that independently modulate both the mass and the duration of ACTH secretory bursts; 3) the differential sensitivity of the CRH- and NAL-stimulated ACTH responses to MET administration suggests that both pituitary and suprapituitary components of the hypothalmic-pituitary-adrenal axis are sensitive to negative regulation over a rapid or intermediate temporal domain. Endogenous cortisol modulates multiple components of dynamical ACTH secretion through composite effects that appear to be mediated through structurally and functionally distinct regulatory domains.

Adrenocorticotropic Hormone↗

PubMed1994

Dose-response study of N,N-dimethyltryptamine in humans. I. Neuroendocrine, autonomic, and cardiovascular effects.

BACKGROUND: To begin applying basic neuropharmacological hypotheses of hallucinogenic drug actions to humans, we generated dose-response data for intravenously administered dimethyltryptamine fumarate's (DMT) neuroendocrine, cardiovascular, autonomic, and subjective effects in a group of experienced hallucinogen users. METHODS: Dimethyltryptamine, an endogenous mammalian hallucinogen and drug of abuse, was administered intravenously at 0.05, 0.1, 0.2, and 0.4 mg/kg to 11 experienced hallucinogen users, in a double-blind, saline placebo-controlled, randomized design. Treatments were separated by at least 1 week. RESULTS: Peak DMT blood levels and subjective effects were seen within 2 minutes after drug administration, and were negligible at 30 minutes. Dimethyltryptamine dose dependently elevated blood pressure, heart rate, pupil diameter, and rectal temperature, in addition to elevating blood concentrations of beta-endorphin, corticotropin, cortisol, and prolactin. Growth hormone blood levels rose equally in response to all doses of DMT, and melatonin levels were unaffected. Threshold doses for significant effects relative to placebo were also hallucinogenic (0.2 mg/kg and higher). Subjects with five or more exposures to 3,4-methylenedioxymethamphetamine demonstrated less robust pupil diameter effects than those with two or fewer exposures. CONCLUSIONS: Dimethyltryptamine can be administered safely to experienced hallucinogen users and dose-response data generated for several measures hypothesized under serotonergic modulatory control. Additional studies characterizing the specific mechanisms mediating DMT's biological effects may prove useful in psychopharmacological investigations of drug-induced and endogenous alterations in brain function.

Adrenocorticotropic Hormone↗

PubMed1994

Dose-response study of N,N-dimethyltryptamine in humans. II. Subjective effects and preliminary results of a new rating scale.

BACKGROUND: Validation of animal models of hallucinogenic drugs' subjective effects requires human data. Previous human studies used varied groups of subjects and assessment methods. Rating scales for hallucinogen effects emphasized psychodynamic principles or the drugs' dysphoric properties. We describe the subjective effects of graded doses of N,N-dimethyltryptamine (DMT), an endogenous hallucinogen and drug of abuse, in a group of experienced hallucinogen users. We also present preliminary data from a new rating scale for these effects. METHODS: Twelve highly motivated volunteers received two doses (0.04 and 0.4 mg/kg) of intravenous (IV) dimethyltryptamine fumarate "nonblind," before entering a double-blind, saline placebo-controlled, randomized study using four doses of IV DMT. Subjects were carefully interviewed after resolution of drug effects, providing thorough and systematic descriptions of DMT's effects. They also were administered a new instrument, the Hallucinogen Rating Scale (HRS). The HRS was drafted from interviews obtained from an independent sample of 19 experienced DMT users, and modified during early stages of the study. RESULTS: Psychological effects of IV DMT began almost immediately after administration, peaked at 90 to 120 seconds, and were almost completely resolved by 30 minutes. This time course paralleled DMT blood levels previously described. Hallucinogenic effects were seen after 0.2 and 0.4 mg/kg of dimethyltryptamine fumarate, and included a rapidly moving, brightly colored visual display of images. Auditory effects were less common. "Loss of control," associated with a brief, but overwhelming "rush," led to a dissociated state, where euphoria alternated or coexisted with anxiety. These effects completely replaced subjects' previously ongoing mental experience and were more vivid and compelling than dreams or waking awareness. Lower doses, 0.1 and 0.05 mg/kg, were primarily affective and somaesthetic, while 0.1 mg/kg elicited the least desirable effects. Clustering of HRS items, using either a clinical, mental status method or principal components factor analysis provided better resolution of dose effects than did the biological variables described previously. CONCLUSIONS: These clinical and preliminary quantitative data provide bases for further psychopharmacologic characterization of DMT's properties in humans. They also may be used to compare the effects of other agents affecting relevant brain receptors in volunteer and psychiatric populations.

Cognition↗

PubMed1993

Prevention of cesarean section. Does intracervical dinoprostone work?

We investigated the effect of preinduction cervical ripening with the intracervical instillation of dinoprostone (prostaglandin E2 gel, 0.5 mg) on the results of labor induced with intravenous oxytocin. We randomly allocated 79 pregnant women to receive either the intracervial application of dinoprostone gel or placebo gel. Compared with control subjects, the group who received dinoprostone had no difference in induction-to-delivery interval or in cesarean section rate. The dinoprostone group had fewer failed inductions, but there was no difference between the two groups in the number who delivered spontaneously within 24 hours. From review of the literature and a meta-analysis, it was likewise revealed that dinoprostone did not favorably affect the cesarean section rate. Contrary to current opinion, intracervical dinoprostone gel does not appreciably lower the cesarean section rate when used at this dose and route before labor is induced.

Administration, Intravaginal↗

PubMed1991

Elevated rectal temperature produced by all-night bright light is reversed by melatonin infusion in men.

Early morning rectal body temperature is lowest when melatonin levels are highest in humans. Although pharmacological doses of melatonin are hypothermic in humans, the relationship between endogenous melatonin and temperature level has not been investigated. We measured rectal body temperature in nine normal men whose melatonin levels were suppressed by all-night sleep deprivation in bright light and compared values with those seen in sleep in the dark, sleep deprivation in dim light (to control for the stimulatory effect of wakefulness on temperature), and sleep deprivation in bright light with an infusion of exogenous melatonin that replicated endogenous levels. Minimum rectal temperature, calculated from smoothed temperature data from 2300 to 0515 h, was greater in bright-light sleep deprivation, resulting in suppression of melatonin, than in conditions of sleep deprivation in dim light or sleep in the dark. An exogenous melatonin infusion in bright light returned the minimum temperature to that seen in dim-light sleep deprivation. A nonsignificant elevation in mean and minimum temperature was noted in all conditions of sleep deprivation relative to sleep. We conclude that melatonin secretion contributes to the lowering of core body temperature seen in the early morning in humans.

Adult↗

PubMed1991

Sleep deprivation reduces LH secretion in men independently of melatonin.

Melatonin affects gonadal function in non-primate mammals. Confirmatory data in man are not available. We assessed melatonin's acute effects on luteinizing hormone secretion in 17 normal men. We studied these men in conditions of sleep in the dark, and sleep deprivation in bright light, dim light, and bright light combined with a physiologically relevant infusion of melatonin, while measuring blood levels of immunoreactive LH every 20 min for 7 h. We compared overnight LH secretion, and LH pulse frequency, amplitude, length, interval and area under the curve using a modification of the PULSAR peak identification program, among the four treatments. Areas under the curve for peaks in all three conditions of sleep deprivation were lower than in normal sleep. The presence or absence of melatonin had no additional effect. We conclude that acute suppression of melatonin does not affect LH pulse parameters in normal man, but that sleep deprivation may reduce the amount of LH secreted per pulse.

Adult↗

PubMed1989

Increase in plasma melatonin, beta-endorphin, and cortisol after a 28.5-mile mountain race: relationship to performance and lack of effect of naltrexone.

Strenuous exercise increases plasma melatonin, cortisol, and beta-endorphin concentrations. Furthermore, a relationship between endogenous opioids and melatonin has been proposed. We measured plasma melatonin, cortisol, and beta-endorphin in 46 subjects before and after a 28.5-mile high altitude race. Thirteen of the subjects received the orally active opioid antagonist naltrexone immediately before the race. The mean plasma melatonin, cortisol, and beta-endorphin levels were higher after the race than before it; the melatonin results were confirmed by gas chromatography-mass spectrometry assay of 12 subjects. Naltrexone had no effect on the increase in any of the three hormones. The run-induced increases in plasma melatonin, beta-endorphin, and cortisol were negatively correlated with finishing time, but only the plasma beta-endorphin and cortisol rises correlated with each other. We conclude that prolonged exercise in trained athletes can increase plasma melatonin and that this rise is not due to the concomitant opioid release.

Adult↗

PubMed1988

Lack of an acute modulatory effect of melatonin on human nocturnal thyrotropin and cortisol secretion.

Using a recently developed model for investigating the neuroendocrine role of melatonin in man, we studied melatonin's effect on the nocturnal secretion of thyrotropin and cortisol in 17 normal male volunteers. The model consists of sleep in the dark and all-night sleep deprivation in conditions of: bright light with and without a melatonin infusion, and dim light. We have improved our infusion paradigm so that levels of melatonin during infusion are now indistinguishable from those occurring during sleep in the dark or dim light sleep deprivation. Sleep deprivation per se raised TSH levels compared to normal sleep. However, the three conditions of sleep deprivation could not be distinguished from each other, which suggests that the suppression of TSH by sleep (or the stimulation of TSH by sleep deprivation) is not mediated by melatonin. Cortisol secretion was unaffected by sleep deprivation regardless of melatonin's presence or absence. However, a difference in the pattern of secretion of cortisol in the sleep condition in the early morning (compared to the sleep deprivation conditions) was noted. These data do not implicate melatonin in the acute regulation of TSH or cortisol in normal man. These data also provide a method of melatonin infusion that replicates the pattern and levels seen in sleep.

Adult↗

PubMed1987

A model for the study of the acute effects of melatonin in man.

The role of the pineal hormone melatonin in human physiology is uncertain. Previous studies correlated plasma melatonin levels with several physiological parameters or determined the responses to pharmacological doses of melatonin during daylight hours. We established an acute model that is more rigorously physiological. Constant nocturnal bright light in sleep-deprived normal men resulted in low plasma melatonin levels throughout the night, in contrast to sleep in the dark and dim light sleep deprivation nights. Subsequently, melatonin was infused during bright light exposure to approximate physiological levels. Plasma GH and PRL measurements in these four conditions revealed an effect of sleep deprivation independent of the presence or absence of melatonin. A subsample of these men had an intermediate level of melatonin suppression with 500 lux light intensity, relative to those during sleep and bright light. The results suggest that melatonin has no acute modulatory effect on the secretion of these two sleep-related hormones.

Adult↗