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Biomedical subjects

M S Wright

Publications and source records attributed to M S Wright.

At least 19 recordsLinked to original sources
PubMed2005

Relative importance of bacteria and fungi in a tropical headwater stream: leaf decomposition and invertebrate feeding preference.

Bacteria and fungi provide critical links between leaf detritus and higher trophic levels in forested headwater food webs, but these links in tropical streams are not well understood. We compared the roles of bacteria and fungi in the leaf decomposition process and determining feeding preference for two species of freshwater shrimp found in the Luquillo Experimental Forest, Puerto Rico, using experimental microcosms. We first tested the effects of four treatments on decomposition rates for leaves from two common riparian species, Cecropia scheberiana (Moraceae) and Dacryodes excelsa (Burseraceae), in laboratory microcosms. Treatments were designed to alter the microbial community by minimizing the presence of bacteria or fungi. The fastest decay rate was the control treatment for D. excelsa where both bacteria and fungi were present (k = -0.0073 day(-1)) compared to the next fastest rate of k = -0.0063 day(-1) for the bacterial-conditioned D. excelsa leaves. The fastest decay rate for C. scheberiana was also the control treatment (k = -0.0035 day(-1)), while the next fastest rate was for fungal-conditioned leaves (k = -0.0029 day(-1)). The nonadditive effect for leaf decomposition rates observed in the control treatments where both fungi and bacteria were present indicate that bacteria and fungi perform different functions in processing leaf litter. Additionally, leaf types differed in microbial colonization patterns. We next tested feeding preference for leaf type and microbe treatment in microcosms using two species of freshwater shrimp: Xiphocaris elongata, a shredder, and Atya lanipes, a scraper/filterer. To estimate feeding preferences of individual shrimp, we measured change in leaf surface area and the amount of particles generated during 5-day trials in 16 different two-choice combinations. X. elongata preferred D. excelsa over C. scheberiana, and leaves with microbial conditioning over leaves without conditioning. There was no clear preference for fungal-conditioned leaves over bacterial-conditioned leaves. This lack of preference for which microbes were responsible for the conditioning demonstrates the importance of both bacterial and fungal resources in these tropical stream food web studies.

Animals↗
PubMed2001

Modulation of C3 gene expression in HepG2 human hepatoma cells.

Inflammation elicits an acute phase response, which includes changes in plasma concentrations of a number of cytokines, reflecting changes in their gene transcription in the liver. In this study, the induction of complement factor 3 (C3) was investigated in HepG2 cells, a human hepatoma cell line often used as a model system for cytokine-dependent expression of acute phase proteins of the liver. By using a very sensitive RT-PCR assay, the amount of mRNA for C3 was measured after induction with lipopolysaccharide (LPS) and interleukin-6 (IL-6). Both substances were found to up-regulate C3 gene expression. C3 mRNA level was lower in LPS-treated cells compared to IL-6 induction and also reached maximum expression at an earlier time point. These findings suggest a coordinate stimulation of C3 expression in the hepatocytes, which then maintains the host response to infectious agents.

Carcinoma, Hepatocellular↗
PubMed2000

Effects of volatile aldehydes from Aspergillus-resistant varieties of corn on Aspergillus parasiticus growth and aflatoxin biosynthesis.

The fungi Aspergillus flavus and Aspergillus parasiticus produce a potent class of hepatocarcinogens known as aflatoxins. Corn-derived volatile compounds have been previously found to affect growth and aflatoxin production in A. flavus. In this study, the effects on A. parasiticus of three corn-derived volatile compounds, n-decyl aldehyde, hexanal and octanal, were measured. These three compounds were previously found to be variably expressed in five Aspergillus-resistant maize strains and three susceptible strains. In this study, A. parasiticus radial growth was restricted least by n-decyl aldehyde and most by octanal. Treatments of 100 microl of both hexanal and octanal were found to completely inhibit radial growth of the fungus using an agar plate assay method. While the volatile compound n-decyl aldehyde had less of an effect on radial growth than the other volatiles, the n-decyl aldehyde treated colonies had a predominance of uniquely aerial hyphae. These colony structures were found to have more complex hyphae and significantly fewer conidiophores than the control and other aldehyde treatments. Furthermore, aflatoxin production by the fungus was reduced by n-decyl aldehyde and hexanal, but was stimulated by octanal. The results presented here indicate that all three volatile compounds reduce radial growth but only n-decyl aldehyde significantly inhibits aflatoxin biosynthesis in A. parasiticus.

Aflatoxins↗
PubMed2000

Attenuated endothelin- mRNA expression with endothelin- receptor blockade during hypoxaemia and reoxygenation in newborn piglets.

UNLABELLED: We investigated the cause of decreased plasma endothelin-1 (ET-1) during hypoxaemia and reoxygenation in newborn piglets subjected to simultaneous blocking of the ET-1 receptors. Changes in plasma ET-1 and prepro-ET-1 mRNA expression in the main pulmonary artery and the left lower lobe in the lung were studied in 1-2-d-old piglets. Ten minutes prior to hypoxaemia, the hypoxaemia group (n = 10) was given saline, two groups (both n = 9) were given 1 and 5 mg/kg i.v. SB 217242 (an ET-1 receptor antagonist). Two groups served as normoxic controls, with and without SB 217242 5 mg/kg i.v. Hypoxaemia was induced by ventilating with 8% O2 until base excess was <-20 mmol/l or mean arterial blood pressure was <20 mmHg. Reoxygenation was performed for 2 h with room air. During hypoxaemia, plasma ET-1 decreased in the hypoxaemia group, remained unchanged in the 1-mg group and increased in the 5-mg group. At the end of reoxygenation, plasma ET-1 was above baseline in the 1-mg and 5-mg groups. In the pulmonary artery, the hypoxaemia group showed 2- to 5-fold higher prepro-ET- 1 mRNA expression compared to all the other groups (p < 0.05). There were trends for higher prepro-ET-1 mRNA expression in pulmonary tissue in the hypoxaemia group compared to the two receptor-blocking groups (p < 0.07). CONCLUSIONS: We conclude that hypoxaemia and reoxygenation increase prepro-ET-1 mRNA expression in the pulmonary artery in newborn piglets. These observations suggest that the half-life of ET-1 is decreased during hypoxaemia and reoxygenation in newborn piglets.

Age Factors↗
PubMed1999

The effects of selected cotton-leaf volatiles on growth, development and aflatoxin production of Aspergillus parasiticus.

The fungi Aspergillus flavus and Aspergillus parasiticus produce the hepatocarcinogenic, secondary metabolites, aflatoxins, in cottonseed, corn, peanuts and treenuts. Results have shown that aflatoxigenic strains of A. flavus and A. parasiticus grown in the presence of specific cotton-leaf volatiles exhibit alterations in aflatoxin production accompanied by variations in growth of the fungi. In this study, two alcohols (3-methyl-1-butanol (3-MB) and nonanol) and two terpenes (camphene and limonene) were chosen as representative cotton-leaf volatiles based on the effects they had on fungal growth and/ or aflatoxin production in previous investigations. The morphological effects of volatile exposure were examined in correlation with fungal growth and aflatoxin production. 3-MB-treated samples exhibited a decrease in fungal radial growth which was directly proportional to the volatile dosage. Additionally, 3-MB treatment resulted in loss of mycelial pigmentation and a decrease in sporulation. Limonene and camphene-treated samples yielded negligible differences in radial growth and morphology when compared to unexposed controls. In addition to radial growth inhibition, samples grown in the presence of nonanol demonstrated uniquely aerial hyphae. In comparison to an unexposed control, aflatoxin production increased in cultures exposed to 3-MB but decreased when exposed to the other three volatiles studied.

Aflatoxins↗
PubMed1998

Isolation and immunocytochemical characterization of three tachykinin-related peptides from the mosquito, Culex salinarius.

Three myotropic peptides belonging to the Arg-amide insect tachykinin family were isolated from whole-body extracts of the mosquito, Culex salinarius. The peptides, APSGFMGMR-NH2, APYGFTGMR-NH2 and APSGFFGMR-NH2 (designated culetachykinin I, II, and III) were isolated and purified on the basis of their ability to stimulate muscle contractions of isolated Leucophaea maderae hindgut. Biologically inactive methionine sulfoxides of two of the three peptides were isolated using an ELISA system based upon antiserum raised against APYGFTGMR-NH2 and identified with mass spectrometry. Immunocytochemistry localized these peptides in cells in the brain, antennae, subesophageal, thoracic and abdominal ganglion, proventriculus and midgut. Nerve tracts containing these peptides were found in the median nerve of the brain, central body, nervi corpus cardiaci, cervical nerve, antennal lobe and on the surface of the midgut.

Amino Acid Sequence↗
PubMed1998

Injury prevention education in United States medical school curricula.

BACKGROUND: In 1993, representatives from the Centers for Disease Control and Prevention recommended that a national injury control training plan be developed that would encourage education about injuries and injury prevention in the required curricula of medical schools. METHODS: A mail survey of curriculum officers was conducted to identify the availability of, characteristics of, and support for educational opportunities in injury prevention at medical schools in the United States. RESULTS: Eighty-seven medical schools (70.2%) responded. Forty-one (47.1%) covered injury prevention in their required curricula. Twenty-six (29.9%) offered nonclinical elective opportunities on injury prevention subjects. In medical schools associated with trauma centers, injury prevention information was almost four times more likely to be included in the required curricula. CONCLUSION: Educational opportunities for medical students in injury prevention are limited. Trauma centers appear to support these efforts at their medical school affiliates.

Curriculum↗
PubMed1998

Stable pediatric blunt trauma patients: is trauma team activation always necessary?

BACKGROUND: An increasing number of studies on adult trauma patients have questioned the need for trauma team activation for stable patients dictated only by mechanism of injury. This triage approach seems to burden the limited resources of the trauma center and may prove to be cost-ineffective. The objective of our study was to determine the predictive value and the sensitivity and specificity of blunt injury mechanism for major trauma in stable pediatric trauma patients. METHODS: Patients 0 to 14 years old injured by injury mechanisms modified from the American College of Surgeons trauma triage criteria and presenting to our American College of Surgeons-verified regional pediatric trauma center from the field between July 1, 1993, and July 31, 1994, were included. Physiologically and anatomically stable patients were identified and subgroup analysis was performed to determine the negative and positive predictive value and sensitivity, and the specificity of blunt injury mechanisms for major trauma [Injury Severity Score > 15] in this group. RESULTS: One hundred ninety-four patients met the study criteria. One hundred forty-three patients (73.6%) had trauma team activation only for mechanism of injury. Of these patients, four patients had Injury Severity Score > 15. The positive and negative predictive values of injury mechanisms modified from the American College of Surgeons trauma triage criteria were 2.8% and 90.2%, respectively, for major trauma in stable pediatric blunt trauma patients. The sensitivity and specificity were 44.4% and 24.9%, respectively. CONCLUSION: Mechanisms of injury seem to have limited value as predictors of injury severity in stable pediatric blunt trauma patients. A modified response level for these patients may prove to be a safe and practical alternative to current practice.

Adolescent↗
PubMed1997

Pediatric injury prevention. Preparing residents for patient counseling.

OBJECTIVES: To describe counseling practices on injury prevention and barriers to patient counseling by pediatric residents and determine whether education about injury prevention or use of educational aids promotes this activity in resident ambulatory practices. DESIGN: Cross-sectional mail survey. SETTING: Accredited US pediatric residency programs. PARTICIPANTS: Pediatric chief residents. MAIN OUTCOME MEASURE: Reported frequencies of patient counseling performed on various injury prevention topics. RESULTS: All residents reported that they were expected to educate patients and families about injury prevention in the continuity clinic setting. Almost all residents (98.5%) reported that they counseled on at least 1 injury prevention topic. On all topics except for poisoning prevention, residents were most likely to counsel patients and families on those topics about which they had received education. Additionally, those residents familiar with the American Academy of Pediatrics The Injury Prevention Program included more injury prevention topics in their counseling repertoire (P = .01). The most frequently identified barriers to counseling included lack of information about the topic and lack of time in the visit. CONCLUSIONS: Most pediatric residents counsel their patients and families on a variety of injury prevention topics. This activity is promoted by the education offered during residency training. Focused efforts should be made to educate residents about those injury topics not being taught and to address counseling barriers with educational interventions that promote prevention counseling during patient visits.

Age Factors↗
PubMed1997

Immunocytochemical localization of testis ecdysiotropin in the pupa of the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae).

Antiserum against testis ecdysiotropin isolated from the gypsy moth, Lymantria dispar, reacted with neurons in the protocerebrum, optic and antennal lobes, subesophageal, thoracic and abdominal ganglia, as well as in nerve tracts extending through the optic lobes, tritocerebrum, and interganglionic connectives of the pupal stage of these insects. Testis ecdysiotropin is a peptide required by immature moths to initiate production of testes ecdysteroid, which is necessary for the development of the male reproductive system and initiation of spermatogenesis. Antiserum against testis ecdysiotropin also detected an accumulation of testis ecdysiotripic-like material between the inner and outer testis sheaths of pupae. The localization of this peptide in the imaginal disks of the last larval stage, cells and nerve fibers in the optic and antennal lobes of the pupa of both sexes, as well as in the testes during development of the adult reproductive system indicates that testis ecdysiotropin has a much larger impact on adult metamorphosis than development of the reproductive system and initiation of gametogenesis. Although this peptide may have a modulatory role in the central nervous system (CNS), it may also initiate a cascade of activity required for the development of the adult nervous system, in addition to its role in reproduction.

Abdomen↗
PubMed1997

Immunologic responses to vaccinia vaccines administered by different parenteral routes.

To develop a less reactogenic but equally immunogenic vaccine, this study of 91 human volunteers compared the safety and immunogenic potency of a new, cell culture-derived vaccinia virus vaccine administered intradermally and intramuscularly with the licensed vaccinia vaccine administered by scarification. Cutaneous pox lesions developed in a higher proportion of scarification vaccinees. Scarification and intradermal vaccine recipients who developed cutaneous pox lesions had more local reactions but also achieved significantly higher cell-mediated and neutralizing antibody responses than those who did not develop pox lesions. Although less reactogenic, intradermal or intramuscular administration of vaccinia vaccine without the concomitant development of a cutaneous pox lesion induced lower immune responses.

Antibodies, Viral↗
PubMed1996

Childhood victims of violence. Hospital utilization by children with intentional injuries.

OBJECTIVE: To describe the utilization of hospital resources by children admitted with intentional injuries. METHODS: A sample of medical records for patients 14 years old and younger admitted to a pediatric tertiary care teaching hospital with a level I pediatric trauma center between January 1, 1991, and December 31, 1992, with intentional injuries (external cause codes E950 to E969) and unintentional injuries (E800 to E949) were reviewed after identification from the trauma center and hospital discharge registries. RESULTS: Of 1495 patients admitted for injuries, 95 had intentional injuries. Among these, 36% were caused by child abuse, 37% were caused by assaults, and the remainder were associated with suicide attempts. Compared with all unintentionally injured patients, those with intentional injuries were similar in gender and race but were significantly older (P<.001). Compared with a randomly selected sample of unintentionally injured patients matched for age, gender, and race, intentionally injured patients had longer mean hospital stays (P<.001), had more medical consultations (P<.001), were more likely to be discharged to sites other than home (P<.001), and had higher hospital charges (P=.007). While intentionally injured children had higher Injury Severity Scores (P=.002), their longer hospital stays were independent of injury severity. CONCLUSIONS: Intentionally injured children use more hospital resources and consequently incur higher hospital charges than those with unintentional injuries. Injury acuity contributes to this phenomenon, as do complex social needs. These data suggest that efforts directed at preventing intentional injuries will significantly affect injury-related health care costs.

Adolescent↗
PubMed1996

Intramuscular ketamine is superior to meperidine, promethazine, and chlorpromazine for pediatric emergency department sedation.

OBJECTIVE: To compare ketamine hydrochloride (KET) with combined meperidine hydrochloride, promethazine hydrochloride, and chlorpromazine hydrochloride (MPC) for pediatric emergency department sedation with respect to onset, duration, and efficacy. DESIGN: Prospective, randomized, double-blind clinical trial. SETTING: Pediatric emergency department in an urban university hospital. PATIENTS: Convenience sample of 29 patients, 6 months to 6 years of age, requiring sedation for suturing, wound or burn debridement, or lumbar puncture. INTERVENTION: Children received intramuscular KET (4 mg/kg) with atropine sulfate (0.01 mg/kg) or MPC (meperidine hydrochloride 2 mg/kg, promethazine hydrochloride 1 mg/kg, chlorpromazine hydrochloride 1 mg/kg). Data collection included demographics, vital signs, and onset of sedation; procedural distress using the Observational Scale of Behavioral Distress; and time to recovery. The operator was questioned on satisfaction with the drug, and parents received follow-up to assess parental satisfaction. RESULTS: Of the 29 patients enrolled in the study, 2 were excluded for protocol violation, 15 received KET, and 12 received MPC. Demographics and baseline vital signs did not differ. Although patients in the 2 groups had a similar duration of sedation (KET, 82 min vs MPC, 97 min, P = .15), patients receiving KET had more rapid onset of sedation (3 min vs 18 min, P < .01) a shorter time to discharge (85 min vs 113 min, P 0 .01) and lower Observational Scale of Behavioral Distress scores (9.9 vs 19.2, P = .003). All 15 physicians using KET would request it again vs 5 of 12 (42%) of the physicians using MPC (P < .001). No serious adverse reactions occurred. There were no differences in parental satisfaction. CONCLUSION: Ketamine has a faster onset and results in more rapid discharge from the pediatric emergency department while providing for less patient distress during procedures. Ketamine is also associated with greater physician satisfaction than MPC.

Child↗
PubMed1996

Identification and characterization of human B-cell epitopes in recombinant antigens of Leishmania aethiopica.

Recombinant DNA fragments from Leishmania aethiopica that code for epitopes which react with human antibodies have been characterized by cross-hybridization studies and DNA sequence analysis. Twenty clones could be grouped into seven different groups (I-VII), probably representing seven different L. aethiopica antigens. The DNA sequences of representative clones from the seven groups have been obtained and the amino acid sequence of the respective recombinant antigens established. The recombinant antigens have been analysed by epitope scanning with patient sera, and octapeptides that contain potential B-cell epitopes have been identified in all seven recombinant antigens. These octapeptides have further been tested with additional patient sera and control sera, and three octapeptides (HAFCHEEG, YHSSVVHD and SYAPCSLK) were found to contain major epitopes recognizing specific antibodies in nine, seven and four, respectively, of the twenty sera tested. Fifteen of the twenty sera reacted with one or more of these three octapeptides.

Amino Acid Sequence↗
PubMed1996

Localization of myosuppressinlike peptides in the hypocerebral ganglion of two blood-feeding flies: horn fly and stable fly (Diptera:Muscidae).

The insect peptides leucomyosuppressin (pEDVDHVFLRFamide) and dromyosuppressin (TDVDHVFLRFamide) have identical chemical sequences with the exception of the N-terminal amino acid; both inhibit spontaneous contraction of insect visceral muscles. Neurons in the hypocerebral ganglion of horn fly, Hematobia irritans (L.), and stable fly, Stomoxys calcitrans (L.), were found to contain material immunoreactive to antiserum produced against the C-terminal of leucomyosuppressin, but not to the N-terminal of dromyossuppressin. Two large lateral clusters containing 8 cells, linked dorsally and ventrally by 2 chains of 6 cells, encircled the anterior surface of the proventriculus and were immunoreactive of leucomyosuppressin and FMRFamide antisera. Axons from these cells were traced to the wall of the aorta and over the surface of the proventriculus. Ultrastructural analysis revealed these cells contained a singular type of elementary secretory granule that contained material of relatively low electron density, both in the cell body and at the axon terminals.

Animals↗
PubMed1995

Update on pediatric trauma care.

Injuries are responsible for more deaths in the pediatric age group than all other causes combined. Care of the injured child, with attention to the way in which patterns of injury and therapeutic responses differ from adults, is a fundamental tenet of pediatric trauma care. As appropriate resource utilization is increasingly mandated, those involved in the care of traumatized children are investigating the efficient application of laboratory and radiologic resources for the evaluation of the pediatric trauma patient and the differential use of hospital resources by various treatment strategies. Familiar diagnostic modalities are put to new uses in the care of the trauma patient. Finally, the alarming increase in violent injury of children and adolescents is bringing a change in the epidemiology of injuries observed in pediatric trauma centers.

Abdominal Injuries↗