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Biomedical subjects

J Carlson

Publications and source records attributed to J Carlson.

At least 181 records · Page 10Linked to original sources
PubMed1993

Neovaginal reconstruction with a rectus abdominis myocutaneous flap.

BACKGROUND: Neovaginal reconstruction after pelvic exenteration has several advantages. Besides the obvious psychosocial benefit to the patient and her partner, the incorporation of viable tissue into the pelvic cavity decreases the incidence of infection and small-bowel complications. Several surgical techniques are available to the gynecologic oncologist for construction of a functional vagina. Recently, myocutaneous flaps incorporating the rectus abdominis and gracilis muscles have been used. Disadvantages of the gracilis myocutaneous flap are the 10-20% incidence of flap loss due to vascular compromise and the potential for prolapse. The rectus abdominis myocutaneous flap is a large flap with a reliable blood supply that allows mobilization without tension on the vascular pedicle, resulting in a much lower incidence of vascular compromise. CASE: We present two case reports, a review of the gynecologic and surgical literature, and the techniques for vaginal reconstruction using the rectus muscle as a myocutaneous flap. CONCLUSIONS: The outcome for both patients was a satisfactory functional vagina that was technically easy to construct. The rectus abdominis myocutaneous flap can provide an adequate neovagina with minimal morbidity.

Abdominal Muscles↗
PubMed1993

Erythrocyte rosetting in Plasmodium falciparum malaria--with special reference to the pathogenesis of cerebral malaria.

Spontaneous rosette formation of uninfected erythrocytes around an erythrocyte infected with Plasmodium falciparum is a recently described in vitro phenomenon which is also present in infections with some other malarial species where sequestration of parasite infected erythrocytes is a characteristic. In the present studies, rosetting was established as a P. falciparum virulence factor, the expression of which is modified by a variety of host factors, such as host immunity, ABO blood group and haemoglobin phenotype. The molecules involved in rosetting seem to be distinct from those involved in endothelial cytoadherence, although they are often co-expressed on the same parasitised red cell. Rosette formation was shown not only to be a phenomenon of laboratory-propagated strains, but also to exist in wild clinical isolates from all major malarious areas of the world. In two studies performed in The Gambia, comprising 211 children with uncomplicated or cerebral malaria, a strong association was found between in vitro rosette formation and cerebral malaria, indicating that rosetting plays a role in the pathogenesis of severe P. falciparum disease. Anti-rosetting activity, presumably mediated by antibodies, was found in sera from patients in malaria-endemic areas, and it was demonstrated that such activity was more abundant in individuals with uncomplicated malaria than in those with cerebral disease, suggesting that humoral immunity protects against rosette formation in vivo. It was also demonstrated, by the use of several independent assays, that erythrocytes from individuals with sickle-cell trait, alpha- and beta-thalassaemia trait or with HbE, formed smaller and weaker rosettes than did normal (HbAA) red cells. The results also suggest that microcytosis per se is correlated to impaired rosette formation. Differences in rosetting ability were also seen between red cells of different ABO blood groups, with a diminished rosetting potential in blood group O red cells. Impaired rosette formation may thus contribute to the innate resistance to severe P. falciparum malaria that is known to exist in certain red cell disorders and in individuals of blood group O. Rosette formation was found to be governed by strong adhesive forces, with lectin-like bindings between parasite-derived proteins exposed on the P. falciparum-infected red cell surface, rosettins, and various carbohydrate moieties present on the uninfected erythrocyte. The strongest carbohydrate receptors seem to be contained within the blood group A or B antigens, and the rosettes were abolished by oligosaccharides mimicking these antigens. The binding between infected and uninfected erythrocytes was dependent on divalent cations and was sometimes sensitive to pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Plasmodium falciparum erythrocyte rosetting is mediated by promiscuous lectin-like interactions.

Herein we describe an assay that was developed to quantitate the binding of normal red blood cells (RBC), labeled with carboxy fluorescein diacetate (C-FDA), to rosetting Plasmodium falciparum-infected RBC. The binding of RBC obtained from various animal species or humans to different strains or clones of rosetting P. falciparum-infected RBC was studied. A strain-specific preference of rosetting was observed for either blood group A/AB or B/AB RBC for all parasites tested. The higher affinity of rosette binding of blood group A, B, or AB vs. O RBC was reflected in larger rosettes when a given parasite was grown in RBC of the preferred blood group. The small size of the rosettes formed when P. falciparum was grown in blood group O RBC may be the in vitro correlate of the relative protection against cerebral malaria afforded by belonging to blood group O rather than to blood group A or B. Rosettes of a blood group A-preferring parasite could be completely disrupted by heparin only when grown in blood group O or B RBC, but not when grown in blood group A RBC. Similarly, the rosettes of a blood group B-preferring parasite could be more easily disrupted by heparin when grown in blood group O or A RBC than when grown in blood group B RBC. Several different saccharides inhibited rosetting of group O RBC, including two monosaccharides that are basic components of heparin. The rosetting of the same parasites grown in blood group A or B RBC was less sensitive to heparin and was specifically inhibited only by the terminal mono- and trisaccharides of the A and the B blood group antigens, the H disaccharide, and fucose. Our results suggest that rosetting is mediated by multiple lectin-like interactions, the usage of which rely on the parasite phenotype and whether the receptors are present on the host cell or not.

ABO Blood-Group System↗
PubMed1992

Alloalbuminemia in Sweden: structural study and phenotypic distribution of nine albumin variants.

Plasma samples exhibiting alloalbuminemia on electrophoresis at pH 8.6 were requested from clinical laboratories throughout Sweden. Nine variants, each representing a different single point mutation, were found in 100 apparently unrelated Swedes. The overall prevalence of alloalbuminemia was estimated at 1:1700. Mutations were identified by protein-structural analysis followed by allele-specific DNA hybridization to verify the most common types. Slightly retarded (+1) mobility was seen in 80 cases. Of these, 71 had the Arg(-2)----Cys proalbumin variant previously called Malmö I proalbumin. Thirteen examples of the second most frequent type, the substitution Lys313----Asn and a mobility change of -1 charge unit, were found, as well as six cases of Glu570----Lys (albumin B) and a single case of Arg-1----Gln (proalbumin Christchurch). Five previously unreported types of alloalbuminemia were identified: four instances of Glu376----Gln, which is the second known mutation at this site; two examples of Asp550----Ala, the second mutation reported at this site; and one example each of Asp63----Asn, Gln268----Arg, and Asn318----Lys. Other mutations were identified among eight subjects of foreign descent. The high frequency and relatively uniform geographic distribution of the Arg-2----Cys mutation suggest that it may have occurred in a founder individual many generation ago in Sweden.

Amino Acid Sequence↗
PubMed1992

Demonstration of interleukin 6 in middle ear effusions.

In response to infection in the middle ear, inflammatory cells produce cytokines--potent regulators and mediators of the immune response. In an earlier study, we demonstrated that levels of the cytokine interleukin 1 were higher in middle-ear effusions from younger children, while levels of the cytokine tumor necrosis factor were higher in middle-ear effusions from older children and in those requiring tympanostomy on multiple occasions. In this study, we evaluated middle-ear effusions for levels of the cytokine interleukin 6. Activities of interleukin 6 include stimulation of bone erosion and production of antibodies and fever. Using an enzyme-linked immunosorbent assay system, significant levels of interleukin 6 (greater than 0.2 pg/mL) were found in 14 (36%) of 39 middle-ear effusions from 25 children with otitis media with effusion. The mean (+/- SE) level of interleukin 6 in middle-ear effusions was 173.9 +/- 74.7 pg/mg of total protein. Like interleukin 1, levels of interleukin 6 were higher in younger children. Tumor necrosis factor may be an important regulator of the local immune response in the middle-ear cleft during persistence of otitis media with effusion, while interleukin 1 and interleukin 6 may be important regulators during the early stages of otitis media with effusion.

Child, Preschool↗
PubMed1992

Development and organization of the Drosophila olfactory system: an analysis using enhancer traps.

Drosophila uses different olfactory organs at different developmental stages. The larval and adult olfactory organs are morphologically dissimilar and have different developmental origins: the antenno-maxillary complex (AMC), which houses the larval olfactory organ, is histolyzed during metamorphosis; the third antennal segment--the principal adult olfactory organ--derives from an imaginal disc. A screen for genes expressed in both larval and adult olfactory organs, but in relatively few other tissues, has been carried out. Seven enhancer trap lines showing reporter gene expression in both the larval AMC and in certain subsets of the adult antenna are described. The antennal staining pattern of one line shows a striking change over the first few days of adult life, with a time course comparable to that of the development of sexual maturity. A pronounced sexual dimorphism in antennal staining pattern is seen in another line. Some staining patterns resemble the patterns of certain classes of antennal sensilla; others show expression restricted to only a small number of cells. Some lines also show expression associated with other chemosensory organs at either the larval or adult stage, including the maxillary palps, labellum, and anterior wing margin. One line, which also shows staining in the male reproductive tract, is male sterile. The significance of these results is considered in terms of (1) the molecular organization of the olfactory system; (2) the recruitment of olfactory genes for use in two developmental contexts; (3) the sharing of genes among different sensory modalities; (4) the role of olfaction in sexual behavior; and (5) posteclosional changes in the olfactory system.

Aging↗
PubMed1992

Olfactory physiology in the Drosophila antenna and maxillary palp: acj6 distinguishes two classes of odorant pathways.

This article provides characterization of the electrical response to odorants in the Drosophila antenna and provides physiological evidence that a second organ, the maxillary palp, also has olfactory function in Drosophila. The acj6 mutation, previously isolated by virtue of defective olfactory behavior, affects olfactory physiology in the maxillary palp as well as in the antenna. Interestingly, abnormal chemosensory jump 6 (acj6) reduces response in the maxillary palp to all odorants tested except benzaldehyde (odor of almond), as if response to benzaldehyde is mediated through a different type of odorant pathway from the other odorants. In other experiments, different parts of the antenna are shown to differ with respect to odorant sensitivity. Evidence is also provided that antennal response to odorants varies with age, and that odorants differ in their age dependence.

Animals↗
PubMed1992

Role of bacterial infection in diet-induced acute pancreatitis in mice.

This study was performed to elucidate the role of bacterial infection in acute pancreatitis in young female mice fed a choline-deficient diet supplemented with 0.5% DL-ethionine (CDE diet). Mice were randomly classified into two groups: one had been fed CDE diet alone (nonantibiotic group), the other was fed a CDE diet with oral administration of antibiotics (antibiotic group). Survival rates at 96 and 144 h after introduction of the CDE diet were significantly improved in the antibiotic group, 25.0 and 19.4%, respectively, as compared with 3.6 and 0% in the nonantibiotic group (p, 0.05). Aerobic and anaerobic bacterial cultures of blood, ascites, spleen, and pancreas were taken from living mice 72 h after introduction of the CDE diet. Positive bacterial growth from one or more of the specimens occurred in 29.4% of the nonantibiotic group, and in 10.0% of the antibiotic group. Mice with pancreatic necrosis had a higher positive culture rate, 62.5% in the nonantibiotic group vs 20.0% in the antibiotic group. These results suggest that reduction of intestinal flora in mice inhibits secondary infection caused by bacterial translocation and improves survival in diet-induced hemorrhagic pancreatitis. We believe the development of bacterial infection of gut origin may be a factor influencing mortality in severe pancreatitis.

Acute Disease↗
PubMed1992

Determining the variability of performance on Wingate anaerobic tests in children aged 6-12 years.

In two parts, this study investigated variability of performance in Wingate anaerobic tests (WAnTs) of normal, healthy, male children aged six, eight, ten and twelve years. The purpose of the first part of the study was to investigate the mean coefficient of variation (C.V. = [S.D./X].100) of children who performed four WAnTs over a period of four weeks. The results revealed age-related differences in the performance data of peak power (PP) and mean power (MP) but no differences between age groups in fatigue index (FI%) = [PP-Pend)/PP.100]. C.V. data from this group of children did not differ significantly between ages in any of the dependent variables. Coggan and Costill (5) measured the variability of male adults during 30 seconds of highly intense cycling and reported C.V.s in PP and MP performances of 6.7 and 6.5%, respectively. C.V.s of children in the first part of the present study were 7.3 and 6.8% for PP and MP, respectively. The C.V. in the FI% of the children (26.7%) however differed substantially from the previously studied adults (10.3%). The second part of the study was conducted to examine the C.V. in FI% performances of children in the WAnT. The purpose of this part of the study was to examine the extent to which a computerized onscreen game, which was linked to pedal cadence affected the variability of children performing WAnTs. A significant decrease was obtained in the C.V. of the FI% in the presence of the computerized feedback game (16.3 and 23.6, with and without the game, respectively). It is suggested that game-based testing procedures may ensure more consistent result in the assessment of pediatric populations.

Anaerobic Threshold↗
PubMed1992

A program model to enhance adherence in work-site-based fitness programs.

We describe a program model designed to achieve high adherence, a major problem for work-site exercise/fitness programs. Our model is a 6-month program consisting of 15 1-hour program meetings, with participants exercising on their own time four times per week. Procedures employed to enhance adherence are contracting, group competition, monitoring, and social support. This program model has been applied nine times. One hundred fifty-nine university employees took part in the initial test with a dropout rate of 9% (15 persons). The average adherence rate for nondropouts was 98%, which is higher than rates usually reported in the literature. Adherence was defined as exercising four times a week.

Adult↗
PubMed1992

Rheological properties of rosettes formed by red blood cells parasitized by Plasmodium falciparum.

A proportion of red blood cells parasitized by Plasmodium falciparum form rosettes with non-parasitized red cells. Although these rosettes are thought to impair microcirculatory flow, their rheological characteristics have not been fully described. Using dual-micropipette manipulation to pull apart individual rosettes, we found that the forces binding rosettes together were strong (average force for removal of a cell was 4.4 x 10(-10) N, approximately 5 times that required to detach a parasitized cell adhered to cultured endothelium). If disrupted rosettes were re-formed, cells rosetted immediately on contact, but the strength of attachment increased over minutes, and did not apparently reach its maximal level for hours. All non-parasitized cells tested could adhere to rosette-forming parasitized cells. Rosettes could withstand arterial flow stresses (1.4-1.6 Pa) for minutes without disintegration. To test the effects of rosetting on flow resistance, the time required for entry into a 4.3 microns pipette was measured. Entry times depended strongly on the number of cells in the rosette, and averaged 35 times longer than for non-parasitized cells. Our studies show that the cell-cell attachments within rosettes are strong, and suggest that rosettes might survive both the arterial circulation and passage through microvessels and could contribute to the ischaemic complications of falciparum malaria.

Animals↗
PubMed1992

Evaluation of transgenic canola plants under field conditions.

Eleven independent transgenic canola (Brassica napus ssp. oleifera L. cv. Westar and Regent) lines were evaluated in the field. The plants carried a neomycin phosphotransferase (NPTII) gene for kanamycin resistance that was introduced via Agrobacterium-mediated transformation. NPTII enzyme assays, Southern blot by hybridizations and progeny analysis, confirmed the stable, heritable integration and expression of the introduced NPTII gene. A number of agronomic characteristics evaluated under field conditions, including maturity yield, and oil and protein content, were all statistically comparable between the transformed and nontransforemd platns. These results indicate that canola can be genetically engineered successfully, and that the Agrobacterium-based transformation system employed does not induced any adverse effects on the intrinsic agronomic and qualitative traits critical to the agricultural industry.

Base Sequence↗
PubMed1992

Molecular mechanisms and biological importance of Plasmodium falciparum erythrocyte rosetting.

Rosetting, i.e. the spontaneous binding of uninfected to malaria infected erythrocytes and endothelial cytoadherence may hinder the blood flow and lead to severe Plasmodium falciparum malaria. Falciparum isolates obtained from unconscious patients all form rosettes and/or express a significantly higher mean rosetting rate than isolates from patients with uncomplicated malaria. Furthermore, sera of patients with cerebral malaria are devoid of anti-rosetting activity while sera from patients with mild disease carry high levels of anti-rosetting antibodies. The presence of anti-rosetting antibodies also seems important for the efficient interaction of rosetting infected rbc and leukocytes. Two parasite derived rosetting ligands of Mr 22K and Mr 28K named "rosettins", have been found on the surface of rosetting infected erythrocytes. CD36 has in at least some strains of parasites been found to function as a rosetting receptor on the uninfected erythrocyte. Heparin disrupts rosettes of P. falciparum in vitro and inhibits the sequestration of rosetting cells ex vivo. In conclusion, rosetting seems a crucial factor in the development of cerebral malaria and treatment of patients with anti-rosetting substances might become an effective adjunct in the treatment of severe malaria.

Animals↗
PubMed1992

The rdgB gene of Drosophila: a link between vision and olfaction.

ota1 (ota = olfactory trap abnormal), an X-linked mutation of Drosophila isolated by virtue of abnormal olfactory behavior, is shown to be an allele of rdgB (retinal degeneration B), a gene required for normal visual system physiology. rdgB function is shown to be necessary for olfactory response of both adult flies and larvae, which have distinct olfactory systems. Electrophysiological recordings from the adult antenna indicate that rdgB is required for normal response in the peripheral olfactory system: some rdgB mutants show a delayed return to the resting potential following stimulation with ethyl acetate vapor. These results indicate that rdgB is required for both visual and olfactory physiology, and they suggest that visual and olfactory transduction may share at least one common molecular step in Drosophila.

Alleles↗
PubMed1992

Rosette formation in Plasmodium falciparum isolates and anti-rosette activity of sera from Gambians with cerebral or uncomplicated malaria.

The ability of Plasmodium falciparum-infected red blood cells (RBC) to form spontaneous erythrocyte rosettes was studied in 130 fresh isolates from Gambian children with cerebral or uncomplicated malaria from August to November 1990. All isolates (24 of 24) from patients with cerebral malaria formed rosettes, but only 61 of 106 isolates from children with uncomplicated malaria formed rosettes. The mean rate of rosette formation in isolates from children with cerebral malaria (28.3%) was significantly greater than that in isolates from children with uncomplicated malaria (8.5%). Giant rosettes were more frequently formed in isolates from patients with cerebral malaria than in those from patients with uncomplicated malaria. Sera of children with cerebral disease generally lacked anti-rosette activity, while many sera from children with uncomplicated malaria showed strong anti-rosette activity when tested against the patients' ow parasites. Some sera that were devoid of autologous rosette-disrupting activity were able to disrupt rosettes formed in other isolates, indicating the presence of different rosette formation mechanisms. Forty percent (6 of 15) of the sera from patients with cerebral malaria caused microagglutination of the patients' own uninfected and infected RBC, while only 10% (3 of 31) of sera from children with uncomplicated disease caused microagglutination. The ability of infected RBC to bind to melanoma cells grown in vitro did not differ between patients with cerebral or uncomplicated malaria. The results of this study, taken in conjunction with our previous findings, establish a strong association between rosette formation in P. falciparum-infected RBC and cerebral malaria.

Adolescent↗
PubMed1992

Ultrastructural analysis of fresh Plasmodium falciparum-infected erythrocytes and their cytoadherence to human leukocytes.

Sixty fresh Plasmodium falciparum isolates obtained from Gambian children with mild or cerebral malaria were investigated by transmission electron microscopy for the expression of knob-like protrusions (K+) on the surface of the infected erythrocytes. More than six-hundred infected erythrocytes were analyzed. Knob-forming parasites were present in all 60 isolates. Although knobless parasites (K-) were found in 25 (42%) of the isolates, only 39 were K-, while 577 were K+. Nine of the 39 K- infected erythrocytes that were studied in greater detail appeared to be asexual parasites because they were either segmented or they lacked mitochondrial DNA-like filaments and cristae, which are abundant in immature gametocytes. No difference was observed in the relative frequency of K+K- infected erythrocytes in isolates from patients with mild or cerebral malaria. Binding of both knobby and knobless infected erythrocytes to autologous leukocytes including monocytes, neutrophils, lymphocytes and plasma cells was found in some of the primary in vitro cultures. By using P. falciparum laboratory strains of known phenotypes and leukocytes from healthy blood bank donors, it was established that this novel adherence phenomenon was related to that of cytoadherence to certain melanoma or endothelial cells. Cytoadherent infected erythrocytes that bind to leukocytes enhance antibody-independent phagocytosis and induce cellular aggregation, while non-cytoadherent or rosetting infected erythrocytes do not.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗