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Biomedical subjects

M E Wilson

Publications and source records attributed to M E Wilson.

At least 199 records · Page 11Linked to original sources
PubMed1994

Family dynamics during the third trimester of pregnancy in Denmark.

Family dynamics in Danish families during the third trimester of pregnancy were explored in relation to family structure, parity, mother-father differences, and normative versus delayed childbearing. There were differences between married and cohabiting families, first- and second-time expectant parents, mothers and fathers, and between normative and delayed first-time expectant parents. For married couples to have better family dynamics than cohabiting couples is surprising for Denmark where both marriage and cohabitation are examples of a nuclear family lifestyle. A dual-path model is conceptualized as a nursing strategy to support the couples' interrelationship during their role transition.

Adolescent↗
PubMed1994

Psychosocial factors associated with the use of bicycle helmets among children in counties with and without helmet use laws.

We examined the extent to which psychosocial factors, in addition to the presence of a law, are associated with the use of bicycle helmets. A mailed questionnaire was completed by 3494 children in fourth, seventh, and ninth grades in three Maryland counties: Howard County, which had a law requiring child bicyclists to wear helmets and an educational campaign; Montgomery County, which had an educational campaign but no law; and Baltimore County, which had neither. Overall, 19% of the respondents reported having worn a bicycle helmet on their most recent ride. In a multiple logistic regression, children's use of helmets in all three counties was significantly associated with their beliefs about the social consequences of wearing helmets and the extent to which their friends wear helmets. Significant interactions were also found, suggesting that in the presence of a law, an educational campaign, or both, children's use of helmets was associated more with social concerns than with parental influences or cognitive factors, such as beliefs about the need for helmets or perceptions of risk. To increase helmet use, the issues of stylishness, comfort, and social acceptability of wearing helmets need to be addressed and more widespread adoption of bicycle helmet laws should be encouraged.

Adolescent↗
PubMed1994

Current trends in the use of intraocular lenses in children.

We present an overview of current practice patterns as they apply to intraocular lens (IOL) implantation in children. Two hundred and thirty-four members of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) and 1,039 members of the American Society of Cataract and Refractive Surgery (ASCRS) responded to a questionnaire. Forty-six percent of AAPOS respondents and 27% of ASCRS respondents reported that they are currently implanting IOLs in children. Although the majority have implanted lenses in children older than six years, 16 AAPOS members and 41 ASCRS members reported implanting IOLs in patients in their first two years of life. Eighty-four percent of the respondents use the continuous curvilinear capsulorhexis technique of anterior capsulotomy in children. When a primary posterior capsulotomy is performed, 63 ASCRS surgeons (38%) reported using posterior continuous curvilinear capsulorhexis. Fixation of an IOL in the ciliary sulcus in a child was acceptable to 67% of the surgeons; however, 86% would not consider implanting an anterior chamber IOL in a child. Implications of the survey data are discussed.

Adolescent↗
PubMed1994

Intraocular lenses for pediatric implantation: biomaterials, designs, and sizing.

Posterior chamber intraocular lenses (IOLs) are being implanted in children with increasing frequency. However, with rare exceptions, only IOLs designed for adults are currently available. These lenses may be difficult to insert into small eyes. Since the pediatric crystalline lens is smaller than that of adults and because the capsular bag does not continue to grow after lensectomy, it is worthwhile to determine the biomaterials, designs, and sizes that may be appropriate for pediatric implantation. In a study of 50 pediatric eyes obtained postmortem, we have documented an estimated growth curve for the developing crystalline lens between birth and 16 years of age. Ninety percent of crystalline lens growth occurs during the first two years of life. Based on these data and this study using the Miyake posterior view analysis of implanted standard and prototype IOLs, we recommend the following: Clinical trials of capsular IOLs, downsized to approximately 10.0 mm diameter, are appropriate for children under two years of age. Capsular IOLs are defined as flexible open-loop, one-piece, all poly(methyl methacrylate), modified C-loop designs made specifically for in-the-bag placement. Because the rapid growth phase of the lens is complete by the age of two, we believe that downsizing the IOL is not necessary after this age unless axial length measurements indicate an unusually small eye. Standard flexible 12.0 mm to 12.5 mm diameter capsular IOLs can be safely implanted. Such lenses could be tolerated throughout life, obviating the need for later IOL exchange.

Adolescent↗
PubMed1994

Comparison of mechanized anterior capsulectomy and manual continuous capsulorhexis in pediatric eyes.

Performing a continuous curvilinear capsulorhexis (CCC) can be more difficult in children than in adults because the capsular bag is more elastic. In this study we compared two capsulectomy techniques in pediatric eyes: creating a mechanized circular anterior capsulectomy using a vitrector and creating a conventional smooth-edged curvilinear tear or CCC using a forceps or needle. We used 18 pairs of eyes (36 eyes) obtained postmortem from children ranging in age from four days to 16 years. The mechanized vitrector-cut capsulectomy was unsuccessful in only one eye (from a 16-year-old child) in which a radial tear developed. Manual CCC was unsuccessful in six eyes, all from children less than five years of age. We conclude that mechanized circular capsulectomy is not only easier to perform in very young eyes than manual CCC, but it is also safe and creates a capsular opening that resists radial tearing. This mechanized technique gives the surgeon an alternative to use in pediatric eyes in which standard manual CCC may be difficult to perform and control.

Adolescent↗
PubMed1994

Pediatric cataract surgery and intraocular lens implantation techniques: a laboratory study.

The use of primary posterior capsulectomy and anterior vitrectomy during pediatric intraocular lens (IOL) implantation has been advocated as a means of preventing the development of posterior capsule opacification. In this study, we used pediatric eyes obtained postmortem to compare two different sequences in the surgical procedure: (1) anterior capsulectomy, lens substance removal, primary posterior capsulectomy with anterior vitrectomy, and IOL implantation in the capsular bag; (2) anterior capsulectomy, lens removal, IOL implantation in the capsular bag, and primary posterior capsulectomy with anterior vitrectomy. Both sequences could be safely performed in the laboratory setting while maintaining stable capsular fixation of the IOL. Placing the IOL in the capsular bag was easier when the posterior capsule was intact (sequence 2). However, both techniques appear feasible for clinical use. Surgeons not familiar with mechanized primary posterior capsulectomy can gain clinically relevant experience by operating on pediatric autopsy eyes in a laboratory setting.

Adolescent↗
PubMed1994

Modulation of the low-affinity IgE Fc receptor (Fc epsilon RII/CD23) by Leishmania chagasi.

Mature B lymphocytes and macrophages express low-affinity receptors for IgE (CD23 or Fc epsilon RII), a multifunctional molecule involved in IgE regulation, B cell growth and antigen presentation. We studied the effect of the protozoan Leishmania chagasi on CD23 expression using a model of early disease. Murine and human B cells, B cell lines, and a macrophage cell line incubated in vitro with the promastigote (PM) form of L. chagasi showed a selective loss of CD23 expression as detected by mAbs and IgE binding. Other B cell surface markers (class II MHC, CD32, surface IgM, surface IgD and gp90MEL-14) remained unchanged, indicating the loss was not due to B cell activation. The CD23 loss was parasite dose-dependent and required contact between PM and B cells. There was a loss of splenic B cell CD23 expression 24 h after infection of BALB/c mice with PM, indicating that the effect also occurred in vivo. During the activation of normal B cells, CD23 is cleaved by a cell-associated protease and released as a soluble form (sCD23). The human B cell line RPMI 8866 showed a 3- to 10-fold increase in the amount of sCD23 released into cultured supernatants when incubated with L. chagasi PM, which paralleled the loss of membrane-bound CD23 from the cell surface. In contrast, the steady-state level of CD23 mRNA did not change appreciably in RPMI 8866 cells during co-culture with PM. Thus, L. chagasi PM selectively down-modulated CD23 expression on B cells and macrophage cell lines, at least in part by increasing the release of sCD23.

Animals↗
PubMed1994

Case report: transverse colon volvulus in a patient with Clostridium difficile pseudomembranous colitis.

Sixty-eight cases of transverse colon volvulus have been reported in the literature. The authors report the first case of transverse colon volvulus in association with Clostridium difficile pseudomembranous colitis, with a review of the available literature. It is possible that the acute inflammation of the colonic mucosa, which occurred from the pseudomembranous colitis in this patient, contributed to the development of volvulus. Further studies are needed to explore the role of mucosal inflammation in the occurrence of volvulus.

Clostridioides difficile↗
PubMed1994

Radiochemical purity testing for 99Tcm-exametazime: a comparison study for three-paper chromatography.

The standard radiochemical purity (RCP) determination uses a three-paper chromatography strip and solvent system (TP). The involvement of multiple strips for calculation of percentage primary, lipophilic 99Tcm-exametazime complex is tedious and time-consuming. The significant streaking of radioactivity on the ITLC/SG MEK strip of the TP method indicates that ITLC/SG MEK may not be an ideal system for RCP analysis of 99Tcm-exametazime. This study was undertaken to compare the standard TP method with two other proposed single-strip chromatography systems: Whatman 17 Chr paper with ethyl acetate (WE) and Gelman Solvent Saturation Pads paper with ether (GE). Our results showed that the solvent developing times (n = 55) and Rf values for TP, WE and GE were 130.4 +/- 9.0 s/0.5-1.0, 205.9 +/- 13.0 s/0.2-1.0 and 90.2 +/- 7.5 s/0.8-1.0, respectively. For RCP values ranging from 45.0 to 94.6% (n = 61), both WE and GE closely correlated with TP (r = 0.97 and 0.96). However, in the intermediate RCP range (i.e. 75-85%, n = 25), the false RCP acceptance rate (i.e. RCP > or = 80%) was 40% (10/25) for the WE method versus 4% (1/25) for the GE method. The GE method has the most clear separation of lipophilic 99Tcm-exametazime from other radiochemical impurities and offers the quickest RCP analysis for 99Tcm-exametazime with relatively accurate results.

Chromatography, Paper↗
PubMed1994

Child abuse, sudden infant death syndrome, infectious disease, and vaccinations.

Clinicians all too often face the difficult dilemma of deciding whether a bone fracture in a young child was intentional. A structured expert consensus process suggests that all rib fractures; midshaft or metaphyseal fractures of the humerus; and fractures of the radius, ulna, tibia, or fibula in children younger than 1 year of age are highly likely to have been caused by abuse. Abused children are more likely to have negative social relationships with other children than their school-aged peers. Research on the causes of sudden infant death syndrome is still confounded by the likelihood that some deaths for which the label was misapplied are included in many studies; however, the presence of smokers in the household in the postnatal period appears to be yet another factor associated with increased risk. Congenital syphilis is on the rise. Detection of infants who have been infected is incomplete. Lack of prenatal care is strongly associated with infection. Cord serology is not sensitive enough to detect all possible cases. Testing of both maternal and neonatal sera results in detection of more infants at risk. Current tests still result in the treatment of some infants who are not themselves infected. Amoxicillin clavulante given twice daily rather then thrice, cefixime given once a day, and a single intramuscular dose of ceftriaxone have all shown acceptable--though not exceptional--cure rates for otitis media. Price is a consideration. Fewer courses of antibiotics would be necessary if more infants were breastfed. Exclusively breastfeeding to at least 4 months cuts the number of bouts of otitis media almost in half.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Capsules↗
PubMed1994

Family dynamics and infant temperament in Danish families.

Transition to parenthood involves the fine balance of family dynamics which both affect, and are affected by, the infant's temperament. The purpose of this study was to investigate changes in family dynamics over the transition to parenthood and the relationship of family dynamics to infant temperament. A sample of 99 families in Odense, Denmark, completed the Family Dynamics Measure in the third trimester of pregnancy and again when the infant was 8-9 months old. At this second time, the mothers also completed the Revised Infant Temperament Questionnaire. Overall we found small changes, although always in a negative direction, in family dynamics over this transition. The largest change was an increase in perceived role conflict reported by both mothers and fathers. Mothers reported more role conflict than fathers. Positive family dynamics were related to infant rhythmicity.

Adult↗
PubMed1994

Benefits of participating in research interviews.

Interviews are a fundamental data collection method used in qualitative health research to help understand people's responses to illness or a particular situation. The risks associated with participating in 1 or 2 hour research interviews when a study focuses on vulnerable populations and sensitive issues are scrutinized by Institutional Review Boards (IRBs) and Human Subjects Committees. This paper shifts attention away from the risks to the benefits and describes catharsis, self-acknowledgement, sense of purpose, self-awareness, empowerment, healing, and providing a voice for the disenfranchised as the sometimes unanticipated benefits reported by interview participants.

Humans↗
PubMed1994

Response of Leishmania chagasi promastigotes to oxidant stress.

At the onset of infection, Leishmania promastigotes are phagocytized by mammalian macrophages. They must survive despite exposure to toxic oxidants such as hydrogen peroxide (H2O2) and superoxide (.O2-) generated during phagocytosis. We investigated the effects of these oxidants on Leishmania chagasi promastigotes and promastigote mechanisms for oxidant resistance. According to spin trapping and electron paramagnetic resonance spectrometry, .O2- could be generated by exposure of promastigotes to the redox-cycling compound menadione. Incubation in either menadione or H2O2 caused a concentration-dependent loss of promastigote viability. However, incubation in sublethal concentrations of H2O2 or menadione caused a stress response in promastigotes. This oxidant-induced response was associated with an increase in the amount of heat shock protein hsp70. Induction of a stress response by exposure of promastigotes either to heat shock or to sublethal oxidants (H2O2 or menadione) caused promastigotes to become more resistant to H2O2 toxicity. Sublethal menadione also caused promastigotes to become more virulent in a BALB/c mouse model of leishmaniasis. We previously correlated H2O2 cytotoxicity for promastigotes with the formation of hydroxyl radical (.OH) from H2O2. However, according to electron paramagnetic resonance spectrometry, the increase in H2O2 resistance after exposure to sublethal oxidants was not associated with diminished generation (i.e., scavenging) of .OH. These data suggest that there is a cross-protective stress response that occurs after exposure of L. chagasi promastigotes to heat shock or to sublethal H2O2 or .O2-, exposures that also occur during natural infection. This response results in increased resistance to H2O2 toxicity and increased virulence for a mammalian host.

Animals↗
PubMed1994

Acquisition of iron from transferrin and lactoferrin by the protozoan Leishmania chagasi.

Leishmania chagasi, the cause of South American visceral leishmaniasis, requires iron for its growth. However, the extent to which different iron sources can be utilized by the parasite is not known. To address this question, we studied acquisition of iron from lactoferrin and transferrin by the extracellular promastigote form of L. chagasi during growth in vitro. A promastigote growth medium based on minimal essential medium supplemented with iron-depleted serum supported promastigote growth only after the addition of exogenous iron. The addition of 8 microM iron chelated to lactoferrin or hemin resulted in normal promastigote growth. Ferritransferrin also supported promastigote growth, but only after a considerable lag. Promastigotes grown in all three iron sources generated similar amounts of hydroxyl radical upon exposure to hydrogen peroxide, indicating that none of these protected parasites against generation of this toxic radical. Promastigotes were able to take up 59Fe chelated to either transferrin or lactoferrin, although uptake from 59Fe-lactoferrin occurred more rapidly. 59Fe uptake from either 59Fe-transferrin or 59Fe-lactoferrin was inhibited by a 10-fold excess of unlabeled ferrilactoferrin, ferritransferrin, apolactoferrin, apotransferrin, or iron nitrilotriacetate but not ferritin or bovine serum albumin. There was no evidence for a role for parasite-derived siderophores or proteolytic cleavage of ferritransferrin or ferrilactoferrin in the acquisition of iron by promastigotes. Thus, L. chagasi promastigotes can acquire iron from hemin, ferrilactoferrin, or ferritransferrin. This capacity to utilize several iron sources may contribute to the organism's ability to survive in the diverse environments it encounters in the insect and mammalian hosts.

Animals↗
PubMed1994

Comparative virulence of blood and stool isolates of Shigella sonnei.

Shigellemia is rare in developed countries and might result from the emergence of unusually virulent strains. We compared systemic invasiveness markers of isolates from the blood of 3 temporally clustered patients with Shigella sonnei bacteremia in Boston with those of 11 unrelated contemporaneous strains from stools of people in New England. We found no difference between the two groups in O-chain length by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, mouse 50% lethal dose, in vivo response to iron, and susceptibility to serum, which varied from moderately susceptible to ultrasusceptible. Mean intraperitoneal 50% lethal doses of smooth form I colonies for mice were equally low (10(5.8) CFU) in both groups, and the 50% lethal doses were lowered equally further in the two groups by predosing with iron to levels useful in mouse model sepsis studies. S. sonnei bacteremia may reflect compromised host defenses, not bacterial virulence.

Adult↗
PubMed1994

Somatostatin analog treatment slows growth and the tempo of reproductive maturation in female rhesus monkeys.

The present study tested the hypothesis that a reduction in serum GH during adolescence would result in slower growth and delayed puberty. Skeletal growth and maturation as well as indices of reproductive development were studied in juvenile female rhesus monkeys receiving a constant sc infusion of a somatostatin analog, Sandostatin, at a dose of approximately 4.50 micrograms/kg BW.day (Ssa; n = 6) and in untreated females (Con; n = 6) from 18 months of age through the luteal phase of the second ovulation. Although age at menarche was similar in Con and Ssa females, first ovulation was delayed significantly in Ssa females, such that the interval between menarche and first ovulation was significantly longer in Ssa females. Serum concentrations of GH, insulin-like growth factor-I (IGF-I), and IGF-binding protein-3 were reduced in Ssa females, particularly after menarche. Although changes in body weight were similar between Ssa and Con females, growth in height was significantly greater in Con females. Furthermore, peak growth velocity in height occurred at a significantly later age in SSa females, but at a similar degree of skeletal maturity. Serum insulin and glucose levels in response to iv glucose were similar in the two groups; however, fasting levels of serum glucose decreased significantly in both groups with advancing age, but the decrease was greater in Con. During the luteal phase of the first 2 ovulatory cycles, there were diminished serum progesterone in 16.7% (2 of 12) of the Con and 41.7% (5 of 12) of the Ssa females. Serum estradiol was significantly lower throughout the first 2 ovulatory cycles in Ssa females, whereas serum LH and IGF-I were similar to those in Con females. Multiple regression analyses revealed that age at menarche was best predicted from the amount of growth in height before menarche, whereas those females who had higher serum IGF-binding protein-3 levels before menarche had an earlier growth spurt, and those who grew faster had a shorter interval between menarche and first ovulation. These data indicate that treatment with a long-acting somatostatin analog, which produces a relative deficiency in the GH axis, slows growth and delays the tempo of puberty. The data suggest that this delay may be due to a reduction in gonadal sensitivity to LH.

Aging↗
PubMed1994

Nursing student perspective of learning in a clinical setting.

The purpose of this qualitative study was to explore and describe nursing students' experience of learning in a clinical practice setting where the students learned to provide care for acutely ill infants. Data were collected using the techniques of observation and ethnographic interviewing. The findings included a nursing student perspective of learning in a clinical setting and consisted of six goals: to do no harm to a patient, to help patients, to integrate theory-based knowledge into clinical practice, to learn clinical practice skills, to look good as a student, and to look good as a nurse. Within this perspective, the students also defined roles for themselves, their instructors, and the staff nurses in the clinical setting. The students defined the learning environment and then used that definition to shape their responses to the educational program.

Attitude↗