Biomedical subjects

M E Stewart

Publications and source records attributed to M E Stewart.

At least 37 records · Page 2Linked to original sources

PubMed1990

Prevention of hypogammaglobulinemia of prematurity with intravenous immune globulin.

We evaluated the effect of 1 g/kg intravenous immune globulin (IGIV) on immunoglobulin levels and half-life, the dose and frequency of IGIV administration necessary to maintain IgG levels at greater than 400 mg/dL, and IGIV effect on immunoglobulin levels after discharge in infants less than or equal to 32 weeks' gestation and less than or equal to 1500 g. Fifteen infants received 31 infusions at IgG levels less than or equal to 400 mg/dL. Immunoglobulin levels were obtained 24 hours postinfusion, weekly during hospitalization, and monthly after discharge. Mean IgG postinfusion was 980 mg/dL. Mean IgG half-life was 18 days (range 7 to 41). Smaller infants with greater than or equal to 5% of blood volume removed per week experienced shorter immunoglobulin half-lives. IGIV caused increased IgG levels after discharge and did not delay endogenous production of IgG. We conclude that 1 g/kg IGIV given to infants less than or equal to 32 weeks' gestation and less than or equal to 1500 g every 1 to 6 weeks during hospitalization, depending on weight and blood volume removed, prevents hypogammaglobulinemia of prematurity.

Dysgammaglobulinemia↗

PubMed1989

Changes in the relative amounts of endogenous and exogenous fatty acids in sebaceous lipids during early adolescence.

Skin surface lipid samples were collected from the scalps of 40 males, aged 9-15, and the lipid class composition of each was analyzed by quantitative thin layer chromatography. The ratio of wax esters/[cholesterol + cholesterol esters] (WE/[CH + CE]) increased with age. The wax ester, cholesterol ester, triglyceride, and free fatty acid classes were isolated from each sample and the fatty acid compositions were determined by capillary gas chromatography of fatty acid methyl esters (FAME) prepared from each lipid class. The concentrations of most of the different types of fatty acids were found to be correlated with the WE/[CH + CE] ratio. Those straight chain fatty acids that are thought to be synthesized mainly within the sebaceous glands, such as 14:0, 14:1, 16:1, and 18:2 delta 5, 8 tended to increase with increasing WE/[CH + CE], while fatty acids which circulate in the blood, such as 18:0, 18:1, and 18:2 delta 9, 12, tended to decrease with increasing WE/[CH + CE]. For the majority of straight chain fatty acid types, the data could be fitted to the equation y = a + b/[x + 1], which can be derived from simple assumptions concerning the origins of the various sebum components. The FAME from the wax esters were separated into saturated and monounsaturated fractions and analyzed by capillary gas chromatography to determine the concentrations of the different types of branched chain FAME present. In the wax esters, straight chain fatty acids tended to increase with increasing WE/[CH + CE], while terminally branched (iso and anteiso) fatty acids tended to decrease. Other branched chain fatty acids increased up to a WE/[CH + CE] ratio of about 2 and then decreased at higher ratios.

Adolescent↗

PubMed1989

Changes in sebum secretion and the sebaceous gland.

New data have shown that sebum secretion is highest in young adults and then declines steadily throughout life in both men and women. This parallels the decline in androgen levels, but this cannot be the sole factor because there is so much overlap in sebaceous gland activity between men and women. The increased occurrence of dry skin in the elderly has been shown to be unrelated to the sebum secretion rate. This is not unexpected, as children, with even less sebum, rarely have this problem. Seborrheic dermatitis, which is also much more common in the elderly, is also unrelated to sebum secretion rate.

Aging↗

PubMed1989

The effectiveness of a cardiopulmonary resuscitation program for mothers of newborn infants.

To investigate the effectiveness of a 15-minute videotape on how to perform cardiopulmonary resuscitation (CPR) on a newborn infant, 28 mothers of normal term babies completed a 12-item test on infant CPR before, immediately after, and 4-6 weeks after viewing the videotape. Statistical analysis showed that the videotape significantly improved scores on the first post-test as compared with the pre-test. At final testing, scores were significantly lower than at the first post-test, but still significantly higher than the pre-test scores. CPR education should be adopted by all institutions providing obstetrical care.

Female↗

PubMed1988

Fatty acids of acylceramides from comedones and from the skin surface of acne patients and control subjects.

Comedonal lipids and skin surface lipids were collected from six acne patients and surface lipids were collected from sex- and age-matched controls without acne. Six series of ceramides were found in each sample, the relative amounts of which were determined by thin-layer chromatography/photodensitometry. Acylceramides (ceramide 1) were isolated by preparative thin-layer chromatography and their ester-linked fatty acids were analyzed by gas-liquid chromatography. The comedonal acylceramides contained higher proportions of 16:0, 16:1 delta 6, and 18:1 delta 6 + delta 8 and much less linoleate (18:2 delta 9,12) than the acylceramides from the skin surface. In the surface lipids from legs, acylceramides from the acne patients contained less linoleate than the acylceramides from control subjects. Free fatty acids from the comedones were also isolated and analyzed, and had a composition very similar to the esterified fatty acids of comedonal acylceramides. The results confirm that fatty acids derived from sebum become incorporated into comedonal acylceramides, displacing linoleate, and show that this process even affects the acylceramides of surface epidermis, more so in acne patients than in normal subjects.

Acne Vulgaris↗

PubMed1988

Digital dermatoglyphics in mammary cancer.

Fingerprints from 200 women with histologically proven breast cancer (case group) were compared to fingerprints from 138 women with no history of any malignant disease (control group). Of the patterns analyzed, four were significantly associated with breast cancer: accidentals, transitionals, angled ulnar loops, and horizontal ulnar loops. A fifth print, the angled radial loop, was found to be of borderline importance as an independent predictor of breast cancer. Of 200 patients in the case group, 27 had one or more accidental prints, 58 had one or more transitionals, 34 had one or more horizontal ulnar loops, and 93 had one or more angled ulnar loop patterns. In 138 control subjects there were 2 with accidental patterns, 21 with one or more transitionals, 6 with horizontal ulnar loops, and 16 with one or more angled ulnar loops. In addition, there appeared to be a gradient of risk; a woman with one type of suspicious print is at higher risk of breast cancer than a woman with none, and two suspicious prints indicate a higher risk than does one. If these findings are confirmed, the prints described will represent a noninvasive anatomical marker of breast cancer risk.

Adult↗

PubMed1988

Reduction in sudden late death by concomitant revascularization with aortic valve replacement.

To determine the impact of coronary atherosclerosis and myocardial revascularization on survival after aortic valve replacement, we reviewed our experience with single aortic valve replacement between 1969 and 1984. Of 474 patients (mean age 62 +/- 13 years), 185 (39%) had no associated coronary artery disease, 233 (49%) had coronary artery bypass grafting, and 56 (12%) had unbypassed coronary artery disease. Early (30-day) mortality rates were 2.2%, 8.2%, and 7.1%, respectively (p less than 0.01, coronary disease absent versus present). Actuarial survival rates at 10 years were 77% +/- 4%, 41% +/- 6%, and 26% +/- 11% (p less than 0.001, coronary disease absent versus present), with 1 to 177 months of follow-up (mean 56 +/- 40). Preoperative angina (39%) did not predict the presence of coronary artery disease (61%). Multivariate logistic regression analysis showed that early deaths were associated with advanced preoperative New York Heart Association functional class (p less than 0.001), advanced age (p less than 0.05), more extensive coronary artery disease (p less than 0.05), and lack of cardioplegic myocardial protection (p less than 0.05). Complete revascularization did not increase operative risk when coronary artery disease was present (early mortality 6.8%, p = not significant). Late deaths were strongly associated with the presence of coronary artery disease (p less than 0.001) and reduced left ventricular ejection fraction (less than or equal to 55%, p less than 0.01). Late cardiac mortality was most commonly attributable to sudden death (30/71, 42%), especially in the unbypassed coronary disease cohort (9/14, 64%). The actuarial rate of freedom from sudden death at 10 years was 52% +/- 17% in the unbypassed coronary artery disease group (p = 0.009), compared with 90% +/- 3% and 91% +/- 3% in the revascularized and no coronary disease patients, respectively. Thus, coexistent coronary atherosclerosis has a detrimental impact on early and late survival after aortic valve replacement. Revascularization does not increase operative risk when associated coronary artery disease is present and significantly reduces the occurrence of late sudden death. Strategies that minimize operative risk when associated coronary artery disease is present include use of cardioplegia and complete revascularization.

Adolescent↗

PubMed1987

Evaluation of a method for measuring the sustainable rate of sebaceous wax ester secretion.

Sebaceous wax ester secretion rates were measured in six subjects on six occasions each, using absorption into bentonite clay and analysis of the collected lipid by quantitative thin-layer chromatography. On each occasion eight samples were collected, four from the left and four from the right side of the forehead in four successive intervals. The first two intervals, which totaled 14 h, were intended to deplete the follicular reservoir of sebum so that a constant rate of absorption could be obtained during the third and fourth intervals, which were 3 h each. Thin-layer analysis of each sample was done in triplicate. The data were examined using analysis of variance techniques to determine the reproducibility of the measurement method and to identify possible sources of variability. The intraclass correlation coefficient (rI) for all 432 post-depletion determinations was 0.80. The reproducibility was considerably better for three of the subjects (rI = 0.93) than for the other three (rI = 0.75). Variability within the latter three subjects did not seem to be attributable to lack of reproducibility in the thin-layer analysis. Real biological variability also seems unlikely considering the holocrine mechanism of sebum secretion. Therefore, the variability probably arises from non-representative collection of sebum into the bentonite absorbent.

Adult↗

PubMed1987

Experimental evaluation of technetium-99m red blood cell radionuclide ventriculography for detecting pericardial bleeding.

Abnormal loculated or diffuse blood pools adjacent to the heart have been observed in patients with pericardial bleeding who have been imaged by gated equilibrium radionuclide ventriculography (RNV). To study the scintigraphic appearance of fresh pericardial blood, we performed equilibrium RNV in six dogs with measured volumes (10, 30, or 50 ml) of intrapericardial blood. Loculated and diffuse pericardial blood was simulated by injecting the blood either into an intrapericardial balloon, or freely into the pericardial space. Ability to detect pericardial blood was determined by blinded review, and blood volume analysis was attempted by measuring its scintigraphic thickness, brightness (relative to the left ventricle), extent, and background-subtracted count rate and a peak count index. Detection rates for 10, 30, and 50 ml were all 100% for loculated pericardial blood, and 67%, 100% and 100% for free pericardial blood, with the use of three scintigraphic views. Visually determined "extent" of the abnormal blood pool was the most reliable indicator of pericardial blood volume. When the volume was 30 ml or more, at least 40% of the heart was surrounded in 26 of 27 cases (96%); the specificity of this finding was 90%. We conclude from this animal study that RNV should be a sensitive method for detecting pericardial bleeding; visual appearance permits qualitative assessment of the volume of accumulated labeled blood.

Animals↗

PubMed1987

The St. Jude valve: analysis of thromboembolism, warfarin-related hemorrhage, and survival.

From March 1978-86, 590 St. Jude prostheses (232 aortic, 232 mitral, and 63 double aortic-mitral) were implanted in 527 patients (mean age 63 years) and followed for up to 8 years (mean 33 months; three lost; 99% complete). The early (30-day) mortality rate was 8.9% and was strongly associated with preoperatively depressed left ventricular function (ejection fraction less than 0.55), ischemic mitral regurgitation, and advanced functional class (IV) (p less than 0.05). Actuarial survival rates at 5 years were 72% +/- 4%, 72% +/- 8%, and 63 +/- 4% after aortic, double, and mitral valve replacement (p less than 0.01). There have been no structural failures. Embolism (28 events, 2.1%/patient-year) was less common with warfarin treatment (1.5%/patient-year; n = 492) than with antiplatelet (3.2%/patient-year; n = 19) or no drug therapy (18.9%/patient-year; n = 16) (p less than 0.01). One embolic event was fatal (3.6%). Warfarin-treated patients remained 91% +/- 1% free of emboli after 8 years. Valve thrombosis (six events; 0.4%/patient-year) occurred exclusively in patients not treated with effective warfarin therapy; one (17%) died. The most common complication was hemorrhage (39 events; 2.9%/patient-year); nine (23%) were fatal, and these constituted 82% of 11 valve-related late deaths. In warfarin-treated patients (target prothrombin time ratio 1.5 to 2.5), hemorrhage was twice as frequent (2.9%/patient-year) as embolism (1.5%/patient-year).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

PubMed1987

Skin surface lipids of the mole Scalopus aquaticus.

Skin surface lipids of the mole Scalopus aquaticus were found to consist principally of squalene (70%), wax esters (15%), and sterol esters (5%), together with small amounts of triglycerides, free fatty acids, free fatty alcohols, and free sterols. Analysis of the fatty acids occurring free and as wax esters and sterol esters showed these to consist of approximately equal amounts of saturated and monounsaturated compounds. The saturated fatty acids consisted predominantly of odd-carbon anteiso and even-carbon straight-chain compounds, with minor amounts of even-carbon iso-branched chains. The unsaturated fatty acids had double bond positions that would have been produced by delta 9-desaturation of C14, C16 and C18 straight chain saturated precursors. Both the free and the esterified fatty alcohols had chain structures corresponding with those of the fatty acids but of somewhat greater average chain length. Discovery of a major proportion of squalene in the sebum of this animal extends the number of non-human species that have this characteristic to four, all of which inhabit a damp environment, suggesting that squalene conveys some biological advantage under these conditions.

Animals↗

PubMed1987

Treatment of severe platelet dysfunction and hemorrhage after cardiopulmonary bypass: reduction in blood product usage with desmopressin.

Impairment of platelet function commonly occurs after cardiopulmonary bypass, and may result in substantial bleeding. Because desmopressin acetate (a synthetic analogue of vasopressin) shortens bleeding time in a variety of platelet disorders, a controlled clinical trial of intravenous desmopressin was performed in 39 patients with excessive mediastinal bleeding (greater than 100 ml/h) and a prolonged template bleeding time (greater than 10 minutes) more than 2 hours after termination of cardiopulmonary bypass. Twenty-three desmopressin recipients and 16 control patients (no desmopressin) were similar in surgical procedure, pump time, platelet count, template bleeding time and amount of bleeding before therapy (p = NS). Compared with the control group, the patients receiving desmopressin (20 micrograms; mean 0.3 micrograms/kg) utilized fewer blood products (29 +/- 19 versus 15 +/- 13 units/patient; p less than 0.05), especially platelets (12 +/- 9 versus 4 +/- 7 units/patient; p = 0.004), while achieving a similarly effective reduction in mediastinal bleeding (4.8- and 4.3-fold, p = 0.001 for both). Severe platelet dysfunction was partially corrected within 1 hour after desmopressin infusion, during which interval no blood products were administered: the template bleeding time shortened (from 17 to 12.5 minutes, p less than 0.05), whereas the platelet count remained unchanged (at 96 +/- 35 and 105 +/- 31 X 10(3)/mm3, p = NS). The plasma levels of two factor VIII components increased: procoagulant activity (VIII:C) from 0.97 +/- 0.43 to 1.52 +/- 0.74 units/ml (p less than 0.05) and von Willebrand factor (VIII:vWF) from 1.28 to 1.78 units/ml (p less than 0.05); these increases correlated with the shortening of the bleeding time (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelet Disorders↗

PubMed1987

Skin lipids: an update.

The stratum corneum lipids, responsible for the epidermal water barrier, consist principally of ceramides, cholesterol, cholesteryl sulfate, and free fatty acids. These lipids are arranged in multiple intercellular lamellae that provide an efficient water barrier because of the crystalline array of the straight and predominantly saturated lipid chains. Interlamellar linkages provided by lipids based on 30-carbon omega-hydroxyacids may be responsible for holding together the intercellular lamellae as well as for assembly of the lamellar granules of the granular cells. The normally ordered exfoliation of corneocytes as they arrive at the surface seems to require hydrolysis of the cholesteryl sulfate to free cholesterol. The sebaceous glands secrete continuously, producing sebum that consists predominantly of triglycerides, wax esters, and squalene. High rates of sebum production per sebocyte result in low levels of linoleate in the sebaceous esters, subjecting the follicular epithelium to essential fatty acid deficiency and the characteristic hyperkeratosis that results in comedo formation. Suppression of sebum production by drugs elevates sebum linoleate concentration and relieves follicular hyperkeratosis. Thus, sebum continues to be a prime suspect in the crime of acne. Low levels of sebaceous gland activity are not correlated with the occurrence of dry skin.

Acne Vulgaris↗

PubMed1987

The effect of 13-cis-retinoic acid on sebaceous glands.

The drug, 13-cis-retinoic acid, which has been demonstrated to have a marked effect on nodulocystic acne, probably has several mechanisms of action. This article summarizes the effects on the sebaceous glands, and the accompanying changes in cutaneous lipids that result from 13-cis-retinoic acid therapy. These changes in lipid composition support the concept that linoleate may be of importance in the pathogenesis of acne.

Acne Vulgaris↗

PubMed1987

Maternally administered antenatal vitamin K1: effect on neonatal prothrombin activity, partial thromboplastin time, and intraventricular hemorrhage.

Infants weighing 1500 g or less at birth are susceptible to intraventricular hemorrhage. This may be due in part to low concentrations of vitamin K-dependent clotting factors. Women in labor between 24-34 weeks' gestation were selected, according to their hospital registration number, to receive 10 mg vitamin K1 intramuscularly at least four hours before delivery. Control women received no vitamin K. The study included only infants born of mothers who were in hospital more than four hours before delivery, who weighed 1500 g or less at birth, and were less than 34 weeks' gestation. Twenty vitamin K1 and 33 control infants qualified for the study. Infants in both groups received routine postnatal vitamin K1. On admission, the infant's prothrombin activity and partial thromboplastin time (PTT) were measured. A head ultrasound was done between days 2 and 4 of life. Results demonstrated significantly improved prothrombin activity, a nonsignificant trend toward improved PTT, and a significantly decreased frequency of intraventricular hemorrhage in infants whose mothers had received vitamin K1. The effect of antenatal vitamin K1 on prothrombin activity and PTT appeared to be more pronounced in female infants.

Blood Coagulation↗

PubMed1986

Effect of cyproterone acetate-ethinyl estradiol treatment on the proportions of linoleic and sebaleic acids in various skin surface lipid classes.

The effect of high-dose cyproterone acetate-ethinyl estradiol treatment on rates of sebum secretion and on the proportions of linoleic acid (18:2 delta 9,12) and sebaleic acid (18:2 delta 5,8) in the skin surface lipids of three female acne patients was examined. Changes in rates of sebum secretion were evaluated indirectly by measuring the ratio of wax esters/(cholesterol + cholesterol esters) in the subjects' skin surface lipid. In two of the subjects, this ratio indicated a reduction of sebum secretion rates to the childhood range. Concomitantly, there was an increase in linoleic acid and a decrease in sebaleic acid in all lipid classes. In the third subject, in whom there was only a small reduction in sebum secretion rate, the proportion of linoleic acid in the cholesterol esters more than doubled, but the changes in the other lipid classes were small or nonexistent. The results indicate that the proportions of linoleic acid and sebaleic acid in sebum are influenced by sebum secretion rates.

Acne Vulgaris↗

PubMed1986

Essential fatty acids and acne.

Acne is characterized by hyperkeratosis of the follicular epithelium, leading to horny impactions that may lie dormant as open or closed comedones or may cause inflammation of the follicle. Although persons with acne have consistently been observed to have elevated levels of sebum secretion, no mechanism relating sebum secretion rates to comedogenesis is known. Acne patients have also been shown to have low levels of linoleic acid in their skin surface lipids. To explain this observation, the hypothesis is advanced that the linoleate concentration in human sebum depends on the quantity of linoleic acid present in each sebaceous cell at the commencement of its differentiation and on the extent to which this initial charge is diluted by subsequent endogenous lipid synthesis in each sebaceous cell. A corollary hypothesis holds that low concentrations of linoleate in sebum impose a state of essential fatty acid deficiency on the cells of the follicular epithelium and induce the characteristic response of hyperkeratosis. Both hypotheses could hold, without there being a systemic deficiency of linoleic acid, simply as the result of elevated lipogenesis in individual sebaceous cells.

Acne Vulgaris↗

PubMed1986

Possible genetic control of the proportions of branched-chain fatty acids in human sebaceous wax esters.

The composition of human sebum varies among individuals with respect to the proportions of various types of fatty acids in the ester lipid classes. Iso-branched fatty acids with even numbers of carbons (iso-even) are particularly variable. However, in 13 identical twin pairs, intrapair differences in the proportions of iso-even fatty acids in sebaceous wax esters were found to be very small, while interpair differences were as large as in the nontwin population. Intrapair differences in iso-even fatty acids were also quite small in 4 of 8 fraternal twin pairs. Heritability estimates suggested that proportions of iso-even fatty acids in human sebum are controlled, at least in part, by genotype.

Adolescent↗