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Biomedical subjects

C E Brown

Publications and source records attributed to C E Brown.

At least 91 records · Page 5Linked to original sources
PubMed1988

Low-dose aspirin. I. Effect on angiotensin II pressor responses and blood prostaglandin concentrations in pregnant women sensitive to angiotensin II.

Decreased incidence of proteinuric hypertension after low-dose aspirin therapy is hypothesized to be a consequence of selective thromboxane A2 inhibition and sparing of prostacyclin. This study was designed to ascertain if low-dose aspirin therapy (81 mg/day for 1 week) alters vascular refractoriness to angiotensin II and the prostacyclin/thromboxane A2 ratio in pregnant women sensitive to angiotensin II (n = 17). Low-dose aspirin increased the effective pressor dose of angiotensin II from 5.9 +/- 2.4 to 10.2 +/- 5.5 ng/kg/min (p less than 0.01, mean +/- SD). Platelet-derived serum thromboxane B2 (a metabolite of thromboxane A2), a measure of therapy compliance, decreased from 1804 +/- 1771 to 132 +/- 206 pg/ml (p less than 0.01). Plasma thromboxane B2 decreased from 130 +/- 107 to 19 +/- 12 pg/ml (p less than 0.01). Inhibition was not selective because 6-keto-prostaglandin F1 alpha (a metabolite of prostacyclin) also decreased from 243 +/- 90 to 163 +/- 90 pg/ml (p = 0.039) and prostaglandin E2 was reduced from 155 +/- 67 to 95 +/- 40 pg/ml (p = 0.014). Decreases in thromboxane B2, however, were significantly greater (75% +/- 19%) than decreases in 6-keto-prostaglandin F1 alpha (21% +/- 33%) or prostaglandin E2 (29% +/- 36%); thus the 6-keto-prostaglandin F1 alpha/thromboxane B2 ratio increased from 3.1 +/- 2.0 to 12.4 +/- 9.9 (p less than 0.01). Although low-dose aspirin increases the effective pressor dose of angiotensin II, it does not return to normal pregnancy values. This observation is consistent with the hypothesis that this represents only a partial selective prostaglandin inhibition.

Angiotensin II↗
PubMed1988

Head computed tomographic scans in women with eclampsia.

From 1980 to 1986, head computed tomographic scans were performed in 49 women with eclampsia managed according to the standardized regimen used at Parkland Memorial Hospital. Abnormal radiographic findings were seen in 14 (29%). Although this incidence may have been affected by the temporal relationship of the scan to the seizure, it was greatly impacted by technical resolution obtained with succeeding improved equipment. In the last 3 years of the study more than a third of these scans showed some abnormality, and in 1986, using "fourth-generation" equipment, half were abnormal. These areas of radiographic hypodensity correspond to those with petechial hemorrhages and local edema that have been described at autopsy in women who died after eclamptic episodes. All women recovered fully despite ominous findings in some. We conclude that the clinical utility of tomography in women with otherwise "uncomplicated eclampsia" is limited because these findings seldom alter management.

Brain↗
PubMed1988

The relationship of social power to visual displays of dominance between men and women.

Two studies, with undergraduate subjects, investigated how sex and situation-specific power factors relate to visual behavior in mixed-sex interactions. The power variable in Study 1 was expert power, based on differential knowledge. Mixed-sex dyads were formed such that members had complementary areas of expertise. In Study 2, reward power was manipulated. Consistent with expectation states theory, both men and women high in expertise or reward power displayed high visual dominance, defined as the ratio of looking while speaking to looking while listening. Specifically, men and women high in expertise or reward power exhibited equivalent levels of looking while speaking and looking while listening. High visual dominance ratios have been associated with high social power in previous research. Both men and women low in expertise or reward power looked more while listening than while speaking, producing a relatively low visual dominance ratio. In conditions in which men and women did not possess differential expertise or reward power, visual behavior was related to sex. Men displayed visual behavior similar to their patterns in the high expertise and high reward power conditions, whereas women exhibited visual behavior similar to their patterns in the low expertise and low reward power conditions. The results demonstrate how social expectations are reflected in nonverbal power displays.

Adult↗
PubMed1988

Prevention and treatment of preterm labor in twins.

It is well established that mothers with twin gestations are at a significant risk of giving birth to a premature infant and, compared to singletons, the perinatal mortality and morbidity are significantly increased. Unfortunately, it is clear that little progress has been made over the past two decades in either the prevention or the treatment of premature labor in twins. The clinician is left with more questions than answers. This latter aspect needs to be recognized by the legal profession. Obviously, more studies regarding the possible beneficial effect of either bedrest or prophylactic beta-sympathomimetics are needed before meaningful recommendations can be made on a universal basis. It is also obvious that more potent tocolytic agents are needed to actually treat premature labor once it occurs. Taking all of these facts into consideration, the authors would recommend the protocol outlined in Table 3 for the general management of twins with regard to premature labor.

Adrenergic Agonists↗
PubMed1988

Comparison of the compression strength of human vertebral bodies with the mass and density of apatite: a study by 31P NMR spectroscopy.

The force needed to fracture individual human thoracic and lumbar vertebral bodies is compared with the mass and density of apatite. 31P NMR spectrometry was used to quantify the apatite, because it permits the mineral content of bone to be determined noninvasively with minimal nonspecific interference from the organic matrix or from variations in composition of the marrow. Experiments were performed with bones of similar structure and function from a single individual with no history of trabecular fractures, to compensate for the effects of the other variables that affect bone strength. The coefficient of correlation between compression strength and the volume density (i.e., g/cm3) of apatite was 0.95. The correlation of strength with the mass (i.e., grams) of apatite in a vertebral body also was reasonably good, r = 0.82, but correlations with areal density (i.e., g/cm2) and linear density (i.e., g/cm) were much poorer.

Apatites↗
PubMed1988

In vivo 31P nuclear magnetic resonance spectroscopy of bone mineral for evaluation of osteoporosis.

The mineral content of stationary bone samples can be quantified by 31P nuclear magnetic resonance (NMR) spectroscopy. The assay can be performed in regions of the anatomy that pose problems for absorptiometric techniques, because the mineral content is measured within a selected volume without concern for the geometry of the bone. In vivo 31P NMR spectra of the bones in human fingers and wrist are reported. Soft tissue such as marrow and skeletal muscle contributes little to the 31P NMR spectra of human fingers and wrist and thus should not seriously affect the accuracy of the mineral assay. 31P NMR spectrometry should prove helpful for confirming rapid bone mineral loss in those at risk and for monitoring response to treatment.

Bone and Bones↗
PubMed1987

Noninvasive evaluation of mineral content of bone without use of ionizing radiation.

The mineral content of bone can be quantified by recording a 31P NMR spectrum while the bone is stationary. The quantity of mineral in the bone is determined from the spectrum with a reference standard by comparison of relative peak areas. The phosphate of bone mineral is readily distinguished from inorganic phosphate and phosphorylated metabolites dissolved in cytosol and from the head groups of phospholipids in membranes. The technical feasibility of constructing a cost-effective instrument for analysis of bone mineral content in the extremities is demonstrated. The possible utility of such a noninvasive assay for detecting osteoporosis and for monitoring the progress of treatment is discussed.

Bone and Bones↗
PubMed1987

Convulsions in hypertensive, proteinuric primiparas more than 24 hours after delivery. Eclampsia or some other cause?

A diagnosis of eclampsia has been considered inappropriate when the onset of a convulsion is greater than 24 hours after delivery. The observations presented here provide strong support for waiving the 24-hour rule, at least when convulsions from no other apparent cause and accompanied by hypertension and proteinuria occur in a primipara as late as 10 days postpartum. Late postpartum eclampsia seems an appropriate term for this very uncommon condition.

Adolescent↗
PubMed1986

Pelvic masses in pregnant patients: MR and US imaging.

Sixteen pregnant patients with pelvic masses detected with ultrasound (US) were studied with magnetic resonance (MR) imaging at 0.35 T. Two patients were in their first trimester, eight in the second, and six in the last. On MR images, 34 masses were seen, including 19 uterine leiomyomas. With US, 20 masses were detected. All masses not seen with US were leiomyomas. Only 20 masses (in 11 patients) were removed for histologic study. In nine cases, MR imaging and US provided similar information on the origin, extent, and type of mass. In seven patients, MR imaging contributed additional information. MR imaging depicted more leiomyomas than US in three patients. In another case, MR images showed that a mass depicted with US was actually a loop of bowel. MR images allowed differentiation between a solid soft-tissue mass and a hemorrhagic fluid-containing mass, correctly depicted the presence of an abdominal pregnancy, and allowed evaluation of the parametrium for spread of cervical carcinoma.

Female↗