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Biomedical subjects

D Long

Publications and source records attributed to D Long.

At least 55 records · Page 3Linked to original sources
PubMed1995

Divalproex sodium and other medications for headache following craniotomy for acoustic neuroma.

Multiple pharmacologic agents were used in attempt to relieve a constant and severe headache in a 47-year-old patient following craniotomy for removal of an acoustic neuroma. Possible etiologies for the unremitting headache are presented. Response to various pharmacologic agents are listed and discussed. During the postoperative course of two surgeries on this patient, it was possible to propose an etiology for the headache by analyzing the mechanisms of each therapeutic agent, along with the patient's response. Divalproex sodium provided complete relief, suggesting the headache is attributable to cell membrane instability.

Anticonvulsants↗
PubMed1995

Characteristics of women treated for cervical cancer at Westmead Hospital. Implications for hospital and community-based health services.

This study was conducted to assess the sociodemographic and histopathological characteristics of women presenting to Westmead Hospital with cervical cancer, and to assess the previous opportunities for Pap smear screening and prevention of this disease. This retrospective review of medical records was carried out in the Department of Gynaecological Oncology at Westmead Hospital, New South Wales, using the medical records of the first 33 women with cervical cancer referred to the newly enhanced Department of Gynaecological Oncology between March and June 1994. Twenty-three (70 per cent) presented with early-stage disease. Interpreters were required for five (16 per cent) patients. Only six women (18 per cent) had been screened for cervical cancer within the last two years and 14 (42 per cent) had never been screened. Many of these women had been attending general practitioners for the management of chronic medical conditions and two had undergone major cardiac surgery at Westmead within the previous two years. There are likely to be new and continuing demands for comprehensive health services for these women, including the use of medical facilities, interpreter services and complex psychosexual counselling. Further, lost opportunities to prevent cervical cancer warrant further study.

Adenocarcinoma↗
PubMed1995

Quantitative comparison of Acanthamoeba castellanii adherence to rigid versus soft contact lenses.

We evaluated quantitative differences in adherence of Acanthamoeba castellanii trophozoites and cysts to new unworn contact lenses as a function of contact lens type and duration of exposure. Daily wear soft (polymacon), disposable soft (etafilcon A), rigid gas permeable (RGP) (siloxane acrylate), and polymethylmethacrylate (PMMA) contact lenses were exposed to 1 x 10(5)/mL log phase A. castellanii (trophozoite:cyst ratio 90:10) for 10 seconds, 30 minutes, 60 minutes, and 120 minutes. The number of adherent organisms was determined by light microscopy and confirmed by scanning electron microscopy. Rates of cyst adherence were similar among contact lens types. We observed significantly greater adherence of trophozoites to RGP and PMMA lenses compared with soft contact lenses (P < 0.05). This difference in trophozoite adherence was significant at all four time periods (P < 0.05). Our findings show that A. castellanii trophozoites and cysts adhere to both soft and rigid contact lens types. We also found that although trophozoite adherence increases as a function of duration of exposure, adherent organisms were observed with exposure times as brief as 10 seconds. This suggests that all contact lens types may be at risk for Acanthamoeba attachment and that even minimal exposure times may be sufficient for lens contamination.

Acanthamoeba↗
PubMed1994

Antigenic implications of human immunodeficiency virus type 1 envelope quaternary structure: oligomer-specific and -sensitive monoclonal antibodies.

A majority of monoclonal antibodies (mAbs) raised against soluble oligomeric human immunodeficiency virus type 1 isolate IIIB (HIV-1IIIB) envelope (env) glycoprotein reacted with conformational epitopes within the gp120 or gp41 subunits. Of 35 mAbs directed against gp41, 21 preferentially reacted with oligomeric env. A subset of these mAbs reacted only with env oligomers (oligomer-specific mAbs). In contrast, only 1 of 27 mAbs directed against the gp120 subunit reacted more strongly with env oligomers than with monomers, and none were oligomer-specific. However, 50% of anti-gp120 mAbs preferentially recognized monomeric env, suggesting that some epitopes in gp120 are partially masked or altered by intersubunit contacts in the native env oligomer. Two mAbs to oligomer-dependent epitopes in gp41 neutralized HIV-1IIIB and HIV-1SF2, and binding of these mAbs to env was blocked by preincubation with HIV-1-positive human serum. Thus, immunization with soluble, oligomeric env elicits antibodies to conserved, conformational epitopes including a newly defined class of neutralizing antibodies that bind to oligomer-specific epitopes in gp41, and may also minimize the production of antibodies that preferentially react with monomeric env protein.

Animals↗
PubMed1994

Outcome of cadaver kidney transplantation in small children.

Small children have often been reported to have poor outcome after kidney transplantation (KT). Recent reports from North America have shown that the use of living-related donors improves patient and graft survival. We report the experience in one centre of primary cadaveric KT using sequential immunosuppression in nine children aged 8-30 months and weighing 5.4-9.8 kg; donors were 0.7-12.3 years old. Four patients had pre-emptive KT and the other five were on peritoneal dialysis; the mean +/- SD waiting time was 2.0 +/- 2.4 months. Perioperative care has been published previously. The surgical approach was intraperitoneal if the aorta and vena cava were used (n = 7) and extraperitoneal for common iliac vessels anastomosis (n = 2); the duration of surgery was 3.5 +/- 0.9 h and the time for vascular anastomosis was 32 +/- 6 min. The recipients received ATG, azathioprine, prednisone and delayed administration of cyclosporin A. The patients were followed for 12-98 (median 41) months and showed good graft function (inulin clearance 63-100 ml/min/1.73 m2); only one child with recurrent haemolytic uraemic syndrome lost his graft three months post-transplantation and died after he had received a second graft. None of the recipients required post-transplant dialysis; arterial hypertension involved four children and was related to graft artery stenosis in two. Growth improved by 0.24 +/- 0.48 SD score of height per year.(ABSTRACT TRUNCATED AT 250 WORDS)

Cadaver↗
PubMed1994

Native oligomeric human immunodeficiency virus type 1 envelope glycoprotein elicits diverse monoclonal antibody reactivities.

We synthesized and purified a recombinant human immunodeficiency virus type 1 (HIV-1) envelope (Env) glycoprotein, lacking the gp120/gp41 cleavage site as well as the transmembrane domain, that is secreted principally as a stable oligomer. Mice were immunized with separated monomeric and oligomeric HIV-1 Env glycoproteins to analyze the repertoire of antibody responses to the tertiary and quaternary structure of the protein. Hybridomas were generated and assayed for reactivity by immunoprecipitation of nondenatured Env protein. A total of 138 monoclonal antibodies (MAbs) were generated and cloned, 123 of which were derived from seven animals immunized with oligomeric Env. Within this group, a significant response was obtained against the gp41 ectodomain; 49 MAbs recognized epitopes in gp41, 82% of which were conformational. The influence of conformation on gp120 antigenicity was less pronounced, with 40% of the anti-gp120 MAbs binding to conformational epitopes, many of which blocked CD4 binding. Surprisingly, less than 7% of the MAbs derived from mice immunized with oligomeric Env recognized the V3 loop. In addition, MAbs to linear epitopes in the C-terminal domain of gp120 were not obtained, suggesting that this region of the protein may be partially masked in the oligomeric molecule. A total of 15 MAbs were obtained from two mice immunized with monomeric Env. Nearly half of these recognized the V3 loop, suggesting that this region may be a less predominant epitope in the context of oligomeric Env than in monomeric protein. Thus, immunization with oligomeric Env generates a large proportion of antibodies to conformational epitopes in both gp120 and gp41, many of which may be absent from monomeric Env.

Amino Acid Sequence↗
PubMed1994

Characterization of human immunodeficiency virus type 1 gp120 binding to liposomes containing galactosylceramide.

Human immunodeficiency virus type 1 (HIV-1) infects some cell types which lack CD4, demonstrating that one or more alternative viral receptors exist. One such receptor is galactosylceramide (GalCer), a glycosphingolipid distributed widely in the nervous system and in colonic epithelial cells. Using a liposome flotation assay, we found that the HIV-1 surface glycoprotein, gp120, quantitatively bound to liposomes containing GalCer but not to liposomes containing phospholipids and cholesterol alone. Binding was saturable and was inhibited by preincubating liposomes with anti-GalCer antibodies. We observed less efficient binding of gp120 to liposomes containing lactosylceramide, glucosylceramide, and galactosylsulfate, whereas no binding to liposomes containing mixed gangliosides, psychosine, or sphingomyelin was detected. Binding to GalCer was rapid, largely independent of temperature and pH, and stable to conditions which remove most peripheral membrane proteins. By contrast, gp120 bound to lactosylceramide could be removed by 2 M potassium chloride or 3 M potassium thiocyanate, demonstrating a less stable interaction. Removal of N-linked oligosaccharides on gp120 did not affect binding efficiency. However, as previously observed for CD4 binding, heat denaturation of gp120 prevented binding to GalCer. Finally, binding was critically dependent on the concentration of GalCer in the target membrane, suggesting that binding to glycolipid-rich domains occurs and that GalCer conformation may be important for gp120 recognition.

Galactosylceramides↗
PubMed1994

Uterine artery Doppler flow velocity waveforms in the second trimester for the prediction of preeclampsia and fetal growth retardation.

OBJECTIVE: To determine the optimal method of measuring uterine artery waveforms with Doppler ultrasound when screening healthy nulliparas for subsequent development of preeclampsia and fetal growth retardation (FGR). METHODS: Color Doppler ultrasound was used to obtain uterine artery waveforms at 19-24 weeks' gestation in 458 nulliparas. In each uterine artery, the resistance index (RI), the ratio between peak systolic (A) and early diastolic (C) blood flow velocities (AC ratio) (a measure of the early notch in the uterine artery waveform), and placental position were recorded. The predictive values of these uterine artery Doppler measurements were evaluated for pregnancy complications. The major end points were preeclampsia and small for gestational age (SGA) infants. RESULTS: The best screening test for preeclampsia and SGA infants was the placental-side uterine artery RI or AC ratio above the 90th percentile for gestational age when the placenta was located on the left or right, and the highest RI or AC ratio when the placenta was midline. This method identified 51% of women with subsequent preeclampsia or SGA infants and had a positive predictive value of 29%. The test detected women with severe disease requiring delivery before 37 weeks with a sensitivity of 83% and specificity of 88%. However, the results were similar if the placental-side uterine artery RI was above an arbitrary cutoff of 0.56 or the AC ratio was above 2.05. A normal test predicted an uncomplicated pregnancy. CONCLUSIONS: Although abnormal uterine artery Doppler is associated with an increased risk of preeclampsia and FGR, the positive predictive values do not support its introduction as a routine screening test in nulliparous women.

Arteries↗
PubMed1993

The maize transposable element system Ac/Ds as a mutagen in Arabidopsis: identification of an albino mutation induced by Ds insertion.

A two-component transposon system based on the Ac element of maize was used as a mutagen in Arabidopsis thaliana. Transposition of a Ds element marked with a hygromycin-resistance gene was activated from four different locations in the Arabidopsis genome. The progeny of 201 plants carrying independent transposition events were screened for mutants with severe, visible phenotypes. Seven mutants were identified and four of them were analyzed genetically. Three mutations were shown to be very closely linked to a transposed copy of the element. Moreover, a mutation (alb3) causing an albino phenotype was conclusively shown to be caused by insertion of the Ds element: somatic and germinal reversion of the mutation occurred in the presence of the transposase gene but not in its absence, and in three revertants the Ds had excised from its position in the mutant line. The DNA adjacent to Ds in the mutant was isolated and it was demonstrated that revertants retained part of the 8-bp duplication caused by insertion of Ds. These experiments indicate that the Ac/Ds system can be used as an insertional mutagen in the heterologous host Arabidopsis, which will permit the isolation of genes from this species by transposon tagging.

Arabidopsis↗
PubMed1993

Analysis of the frequency of inheritance of transposed Ds elements in Arabidopsis after activation by a CaMV 35S promoter fusion to the Ac transposase gene.

The Ac/Ds transposon system of maize shows low activity in Arabidopsis. However, fusion of the CaMV 35S promoter to the transposase gene (35S::TPase) increases the abundance of the single Ac mRNA encoded by Ac and increases the frequency of Ds excision. In the experiments reported here it is examined whether this high excision frequency is associated with efficient re-insertion of the transposon. This was measured by using a Ds that carried a hygromycin resistance gene (HPT) and was inserted within a streptomycin resistance gene (SPT). Excision of Ds therefore gives rise to streptomycin resistance, while hygromycin resistance is associated with the presence of a transposed Ds or with retention of the element at its original location. Self-fertilisation of most individuals heterozygous for Ds and 35S::TPase produced many streptomycin-resistant (strep(r)) progeny, but in many of these families a small proportion of strep(r) seedlings were also resistant to hygromycin (hyg(r)). Nevertheless, 70% of families tested did give rise to at least one strep(r), hyg(r) seedling, and over 90% of these individuals carried a transposed Ds. In contrast, the Ac promoter fusion to the transposase gene (Ac::TPase) produced fewer strep(r)hyg(r) progeny, and only 53% of these carried a transposed Ds. However, a higher proportion of the strep(r) seedlings were also hyg(r) than after activation by 35S::TPase. We also examined the genotype of strep(r), hyg(r) seedlings and demonstrated that after activation by 35S::TPase many of these were homozygous for the transposed Ds, while this did not occur after activation by Ac::TPase. From these and other data we conclude that excisions driven by 35S::TPase usually occur prior to floral development, and that although a low proportion of strep(r) progeny plants inherit a transposed Ds, those that do can be efficiently selected with an antibiotic resistance gene contained within the element. Our data have important implications for transposon tagging strategies in transgenic plants and these are discussed.

Arabidopsis↗
PubMed1993

Changing survival and impairment rates at 18-24 months in outborn very low-birth-weight infants: 1984-1987 versus 1980-1983.

Outcomes at 18-24 months corrected age of very low-birth-weight infants admitted to our Neonatal Intensive Care Unit in 1984-1987 (period 2) were compared with the outcomes of infants admitted in 1980-1983 (period 1) (total 1357 infants). In the 500-750-g birth-weight subgroup, the survival rate increased from 32 to 54% (p = 0.002). Rates of moderate and severe impairment at 18-24 months (neurosensory deficit, or Bayley corrected mental developmental index < or = 68) in this subgroup decreased from 41 to 15% (p = 0.005), and in those without severe impairment, mean mental Bayley scores in periods 1 and 2 were 84 +/- 18 and 90 +/- 16, respectively (p = 0.20). Analysis after exclusion of small-for-gestational-age infants gave similar results. In the small-for-gestational-age infants of birth weight 500-750 g, the survival rate increased but the impairment rate was unchanged between periods. It is concluded that outcomes improved in 1984-1987 compared with 1980-1983 only for infants with birth weight of 500-750 g.

Birth Weight↗
PubMed1993

Comparison of two kits for measuring ferritin in blood.

Ferritin concentrations in blood are a good indicator of iron stores and can be measured in plasma or serum with commercial kits. We have measured plasma ferritin content in infants ranging from 3 to 15 months of age. During the first three years of a four-year study, plasma samples drawn from these infants were shipped to Abbott Laboratories in Chicago and assayed using the Ferrizyme immunoassay technique (Abbott Laboratories, Chicago, Illinois). For the last year of the study, we analyzed the remaining samples in St. John's using the radioimmunoassay GammaDab125 I Kit (Baxter Travenol Diagnostics, Inc., Cambridge, Massachusetts). Both kit manufacturers report inter- and intra-assay variability of < or = 5%. Results for samples analyzed by the second method were higher than earlier results from infants of the same age with the same intakes of iron; thus, we decided to analyze subsequent samples with both kits.

Ferritins↗
PubMed1992

[Propofol versus etomidate in short-time urologic surgery].

Thirty patients, scheduled for short urological surgical procedures and ranked ASA 1 or 2, were randomly assigned to two homogenous groups. In group P, they were given a 2 mg.kg-1 bolus of propofol and 10 micrograms.kg-1 of alfentanil, followed by a continuous infusion of propofol (5 mg.kg-1.h-1) and 5 micrograms.kg-1 doses of alfentanil. In group E, they were given a 0.3 mg.kg-1 bolus of etomidate, followed by an infusion (1.5 mg.kg-1.h-1). The doses of alfentanil were the same as in group P. Further doses of either propofol (0.5 mg.kg-1) or etomidate (0.2 mg.kg-1) were used should anaesthesia prove not to be deep enough. The patients were not intubated, and breathed spontaneously. Surgery lasted a mean of 18.3 +/- 11.8 min (group P) and 18.8 +/- 9.4 min (group E). The following parameters were studied: the amount of each agent required for maintenance of anaesthesia, the duration of apnoea at induction, the quality of anaesthesia and of muscle relaxation, adverse effects (coughing, trismus, restlessness, nausea, vomiting), the time required for recovery, and its quality. In group P, there was a 27% decrease in arterial pressure, without any tachycardia or hypoxia, together with a quick recovery of excellent quality. On the other hand, in group E, there was little or no haemodynamic alteration, but there often was a trismus at induction. Hypoxia also occurred during induction with etomidate, being severe enough in one case to require tracheal intubation and artificial ventilation. The reasons for this hypoxia seemed to be the apnoea and the trismus, which tends to hinder assisted ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Disulfide bond structure of glycoprotein D of herpes simplex virus types 1 and 2.

Glycoprotein D (gD) is a structural component of the herpes simplex virus envelope which is essential for virus penetration. The function of this protein is highly dependent on its structure, and its structure is dependent on maintenance of three intact disulfide bonds. gD contains six cysteines in its ectodomain whose spacing is conserved among all its homologs in other alphaherpesviruses as well as Marek's disease virus. For other proteins, conservation of cysteine spacing correlates with conservation of disulfide bond structure. We have now solved the disulfide bond structure of gD-1 and gD-2 of herpes simplex virus types 1 and 2, respectively. Two approaches were used. First, we constructed 15 double-Cys mutants of gD-1, representing all possible disulfide pairs. In each case, codons for cysteines were changed to serine. We reasoned that if two cysteines normally form a disulfide bond, double mutations which eliminate one proper bond should be less harmful to gD structure than double mutations which eliminate two disulfide bonds. The mutated genes were cloned into a eucaryotic expression vector, and the proteins were expressed in transiently transfected cells. Three double mutations, Cys-1,5, Cys-2,6, and Cys-3,4 permitted gD-1 folding, processing, transport to the cell surface, and function in virus infection, whereas 12 other double mutations each produced a malfolded and nonfunctional protein. Thus, the three functional double-Cys mutants may represent the actual partners in disulfide bond linkages. The second approach was to define the actual disulfide bond structure of gD by biochemical means. Purified native gD-2 was cleaved by CNBr and proteases, and the peptides were separated by high-performance liquid chromatography. Disulfide-linked peptides were subjected to N-terminal amino acid sequencing. The results show that cysteine 1 (amino acid [aa] 66) is bonded to cysteine 5 (aa 189), cysteine 2 (aa 106) is bonded to cysteine 6 (aa 202), and cysteine 3 (aa 118) is bonded to cysteine 4 (aa 127). Thus, the biochemical analysis of gD-2 agrees with the genetic analysis of gD-1. A similar disulfide bond arrangement is postulated to exist in other gD homologs.

Amino Acid Sequence↗