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Biomedical subjects

C D Wood

Publications and source records attributed to C D Wood.

At least 19 recordsLinked to original sources
PubMed2001

Transcription inhibition induced by modified triple helix-forming oligonucleotides: a quantitative assay for evaluation in cells.

Oligonucleotides can bind to double-stranded DNA in a sequence-specific manner to form triple helices. Uniformly modified, pyrimidine-rich oligodeoxyribonuclotides containing internucleosidic N3'-P5' phosphoramidate linkages are known to form very stable triplexes with their DNA target. Psoralen-conjugated triple helix-forming oligonucleotides (Pso-TFOs) can additionally be photo-induced to become irreversibly bound to their targeted DNA sequence. Here, we have examined the ability of various 15-mer phosphoramidate TFOs targeted to the HIV-1 polypurine tract (PPT) sequence to prevent transcription elongation in cell cultures; the PPT sequence has been cloned in the transcribed region of a reporter firefly luciferase gene (luc) and transient expression experiments performed. We show that the level of transcription inhibition of the reporter gene in cells perfectly correlates with the amount of covalent triplex at the PPT site. The efficacy of non-covalent triplexes (either omitting the irradiation step with the psoralen conjugate, or using the unsubstituted oligonucleotide) has been studied in our expression system; the oligonucleotides were introduced into living cells by cationic lipid-mediated delivery or directly into the cell nucleus by microinjection. This experimental approach allowed us to evaluate the intrinsic activity of triplexes as transcriptional inhibitors; transcription elongation was inhibited in cells in a sequence-dependent and concentration-dependent manner. This experimental system is convenient for quantitative and fast evaluation of new chemistries of antigene oligonucleotides as inhibitors of gene expression in cells and in vivo.

Base Sequence↗
PubMed2001

Characterization of the ethanol-inducible alc gene-expression system in Arabidopsis thaliana.

Controlled expression of transgenes in plants is key to the characterization of gene function and the regulated manipulation of growth and development. The alc gene-expression system, derived from the filamentous fungus Aspergillus nidulans, has previously been used successfully in both tobacco and potato, and has potential for use in agriculture. Its value to fundamental research is largely dependent on its utility in Arabidopsis thaliana. We have undertaken a detailed function analysis of the alc regulon in A. thaliana. By linking the alcA promoter to beta-glucuronidase (GUS), luciferase (LUC) and green fluorescent protein (GFP) genes, we demonstrate that alcR-mediated expression occurs throughout the plant in a highly responsive manner. Induction occurs within one hour and is dose-dependent, with negligible activity in the absence of the exogenous inducer for soil-grown plants. Direct application of ethanol or exposure of whole plants to ethanol vapour are equally effective means of induction. Maximal expression using soil-grown plants occurred after 5 days of induction. In the majority of transgenics, expression is tightly regulated and reversible. We describe optimal strategies for utilizing the alc system in A. thaliana.

Arabidopsis↗
PubMed2000

Targeted inhibition of transcription elongation in cells mediated by triplex-forming oligonucleotides.

Triple-helix-forming oligonucleotides (TFOs) bind in the major groove of double-stranded DNA at oligopyrimidine small middle dotoligopurine sequences and therefore are candidate molecules for artificial gene regulation, in vitro and in vivo. We recently have described oligonucleotide analogues containing N3'-P5' phosphoramidate (np) linkages that exhibited efficient inhibition of transcription elongation in vitro. In the present work we provide conclusive evidence that np-modified TFOs targeted to the HIV-1 polypurine tract (PPT) sequence can inhibit transcriptional elongation in cells, either in transient or stable expression systems. The same constructs were used in transient expression assays (target sequence on transfected plasmid) and in the generation of stable cell lines (target sequence integrated into cellular chromosomes). In both cases the only distinguishable feature between the cellular systems is the presence of an insert containing the wild-type PPT/HIV-1 sequence, a mutated version with two mismatches, or the absence of the insert altogether. The inhibitory action induced by np-TFOs was restricted to the cellular systems containing the complementary wild-type PPT/HIV-1 target, and consequently can be attributed only to a triple-helix-mediated mechanism. As a part of this study we also have applied an imaging technique to quantitatively investigate the dynamics of TFO-mediated specific gene silencing in single cells.

Animals↗
PubMed2000

Prokinetic effects of erythromycin after antimotion sickness drugs.

Motion sickness and the antimotion sickness drugs scopolamine (SCP) and promethazine (PMZ) inhibit gastric emptying (GE). This study was conducted to determine if erythromycin would exert its well-known prokinetic effects in normal and motion-sick subjects given antimotion sickness drugs. Fifteen fasted volunteers (11 males, 4 females) participated in the study. In control tests, 8 subjects were given intramuscular (i.m.) saline (SAL, 0.5 ml), SCP (0.1 mg), or PMZ (25 mg). GE of liquid (300 ml) containing 1 mCi of Tc 99m diethylenetriaminepentaacetic acid (DTPA) was measured by sequential gastric scintigraphy 30 minutes after i.m. treatments. In other tests, GE was measured in 8 subjects after each i.m. treatment, followed 10 minutes later by 200 mg of erythromycin ethylsuccinate (ESS) suspension given orally. In a third group of tests, 7 subjects received an i.m. treatment, oral EES 10 minutes later, and were then brought to an advanced level of motion sickness short of vomiting. To induce motion sickness, blindfolded subjects made timed head movements while seated in a rotating chair. GE was measured immediately after rotation. GE half-life, rate constant, area under the curve (AUC), and lag time were calculated using conventional mathematical methods for analyzing exponential rate processes. GE parameters calculated for normal and motion-sick subjects given antimotion sickness drugs and EES were compared with those from subjects given i.m. treatments (control) only. In normal subjects, EES significantly (p < 0.05) increased the GE rate constant for all i.m. treatments and reduced the AUC for SAL, SCP, and PMZ by 49% (p < 0.05), 44% (p < 0.05), and 69% (p < 0.01), respectively. In motion-sick subjects, lag time was significantly (p < 0.05) increased, and the rate constant and AUC values were unchanged from control for all i.m. treatments. The authors conclude that oral EES reverses the gastrostatic actions of the antimotion sickness drugs but does not affect the inhibition of gastric emptying associated with motion sickness. The results suggest that motion sickness and antimotion sickness drugs reduce GE through different mechanisms.

Administration, Oral↗
PubMed1998

Real-time imaging of gene expression in single living cells.

Recent advances in reporter gene technologies are now allowing us to image gene transcription at the single cell level, using either fluorescence or luminescence microscopy. Here, the basis of these techniques is outlined and their advantages and disadvantages in various biological systems are discussed.

Animals↗
PubMed1998

Dynamic changes in prolactin promoter activation in individual living lactotrophic cells.

The firefly luciferase gene has become widely used as a convenient reporter for studies of gene promoter regulation. Very recently, the development of ultralow-light imaging cameras has enabled the quantitative digital imaging of light signals resulting from luciferase activation in the presence of luciferin substrate. We have applied this technology to the study of PRL promoter activation in individual pituitary tumor cells to study the temporal and spatial characteristics of the expression of a well-characterized pituitary hormone gene. Rat pituitary GH3 cells were transfected by lipofection with a luciferase reporter gene linked to 5000 bp from the human PRL gene 5'-flanking region. A series of stably transfected cell clones were generated, and one of these was chosen for detailed study on the basis of appropriate regulation of high-level luciferase expression by a series of known stimuli including TRH, forskolin, the calcium channel agonist Bay K8644, and basic fibroblast growth factor (bFGF). These cells were subjected to direct imaging of luciferase activity using a Hamamatsu photon-counting camera linked to a Zeiss Axiovert microscope with an Argus-50 image processor. Cells were exposed to 1 mM luciferin, and images were integrated over 30-min periods for up to 72 h. The total photon count over a given field settled to steady levels within 10 h and then remained constant for over 55 h. Addition of forskolin, TRH, or bFGF increased the total photon count of fields of 20-100 cells by 2- to 4-fold consistent with previous data from transient expression assays using the human PRL promoter. Individual cells, on the other hand, showed marked marked temporal and spatial heterogeneity and variability of luciferase expression when studied at 3-h intervals. Unstimulated cells showed variable luciferase expression with up to 40-fold excursions in photon counts per single cell area within 12-h periods. Stimulation of cells with either TRH, forskolin, or bFGF resulted in smooth increases in photon output over fields of 20-100 cells, but again individual cell responses differed widely, with some cells showing slow progressive rises in photon output, others showing phasic or transient responses, and yet others showing no response. In conclusion, we found a surprising degree of heterogeneity and temporal variability in the level of gene expression in individual living pituitary tumor cells over long periods of time, with markedly divergent responses to hormonal or intracellular stimulation. The use of stably transfected clonal cell lines with extended periods of reporter gene imaging offers a valuable insight into control of gene expression in living cells in real time.

Animals↗
PubMed1996

The nutritive value of stackburned yellow maize for livestock: tests in vitro and in broiler chicks.

Difference in the nutritive value of four grades of stackburned yellow maize, obtained from a single storage unit in Mozambique, were examined. Samples were analysed for chemical composition, and subjected to the following in vitro assays for estimating digestibility: total dietary fibre and pancreatin for non-ruminants, and gas production using sheep rumen fluid for ruminant livestock. Samples were also fed to broiler chicks at 600 g/kg diet in a growth trial. There were no significant differences in crude protein contents of the maize samples, but there was evidence for the development of Maillard reaction products. Detectable amino acids were lower in discoloured maize, with decreases of 52% in lysine, 35% in arginine, and 15% in glycine concentration in the most severely discoloured sample compared with control. Total starch, reducing sugar, acid-detergent fibre and amylase-neutral-detergent fibre values increased, while total non-reducing sugar content decreased with increased discolouration. Total dietary fibre and pancreatin assays indicated a lowering in digestibility of maize with increasing discolouration. Weight gain of chicks (P = 0.0228), efficiency of feed utilization (P = 0.0009) and the metabolizable energy value of diets decreased (P < 0.0001) with increasing stackburn discolouration. There were no significant effects on N retention of diets. In vitro fermentation using sheep rumen fluid showed a linear decrease in gas production with increasing maize discolouration, indicating a reduction in rumen degradability with stackburn.

Aflatoxins↗
PubMed1994

Habituation and motion sickness.

The vestibular, cerebellar, and reticular systems are central in importance, in motion sickness and habituation, to the effects of motion. Nuclear medicine single photon emission computed tomography (SPECT) studies of cerebral blood flow and power spectral electroencephalographic recordings during motion sickness were used to determine alterations in the central nervous system. The rotating chair with and without visual stimulation was used to study the rate of habituation and the effect of antimotion sickness medications on this rate. An increase of theta waves over the frontal cortex indicated a decreased activation of the higher centers during motion sickness. Motion sickness also produces an increase of blood flow in the central cerebellum that has connections to the reticular system. This increase in cerebellar activity is relayed to the reticular system whereby neural recruitment builds up to trigger the vomiting center, producing motion sickness. Habituation may be a conditioned compensatory activation of the reticular neurons that prevents this disruption of normal activation. The rate of habituation when motion sickness was prevented by scopolamine was slowed, indicating that, if the central nervous system is not challenged by disruption of normal activation, it does not produce the compensatory reactions that result in habituation.

Adult↗
PubMed1994

Effects of motion sickness and antimotion sickness drugs on gastric function.

This study examined the effects of motion sickness and antimotion sickness drugs on gastric emptying (GE). Drugs were tested in normal and motion sick subjects. To induce motion sickness, subjects performed head movements while seated in a rotating chair. Gastric emptying of liquid (300 mL) was determined by nuclear medicine techniques, whereas gastric electrical activity, the electrogastrogram (EGG), was monitored from surface (cutaneous) electrodes positioned over the abdominal area. Gastric emptying was severely inhibited at the peak of motion sickness symptoms, but returned to normal 15 minutes later when symptoms abated. In normal (non-motion sick) subjects intramuscular (IM) scopolamine (0.1 mg) and IM promethazine (25 mg) inhibited GE, whereas erythromycin ethylsuccinate (EES) suspension (200 mg) given orally increased GE. When administered to motion sick subjects, IM scopolamine and IM promethazine added slightly, but not significantly, to the inhibition of GE already present. Oral EES did not significantly alter GE in motion sick subjects. Although EGG frequency remained within normal limits (approximately 2.5-3.5 cpm) after liquid ingestion in both normal and motion sick subjects, EGG amplitude was differentially affected in the two groups. Electrogastrogram amplitude increased twofold to fourfold after liquid ingestion in normal, but not in motion sick subjects. The results suggest that (1) maximal inhibition of GE is coincident with peak motion sickness symptoms, (2) both IM scopolamine and IM promethazine inhibit GE in normal subjects, but do not add significantly to the inhibition of GE already established during motion sickness, (3) orally administered erythromycin enhances GE in normal, but not in motion sickness subjects, and (4) the normal stimulatory effect of liquid ingestion on gastric motility does not occur in motion sick subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The Seattle appropriate level of care survey: health status and health services use in ambulatory persons with AIDS.

We surveyed 77 persons with AIDS, their physicians and their social workers during the autumn of 1987 to ascertain health status and to quantify use of health services in Seattle, Washington. Participants included the majority (59%) of persons living with AIDS in the area. Information was gathered regarding demography, health status, functional status, medical history and the use of health services. The validity of self-assessed general health was corroborated by the physician-rated Karnovsky score (kappa = 0.59), by social worker assessment (kappa = 0.41), and by correlation with functional status (r = 0.6-0.8). We found more frequent use of health services (categorized into skilled services, chore services and physician services) among AIDS patients who were dependent in basic and instrumental daily activities, had low income, had poor self-assessed general health, lived alone or lacked an available support person at home. These associations persisted in multivariate analyses, and accounted for 6-23% of the variability in service use. We conclude that health and functional status of persons with AIDS can be estimated via mailed questionnaires and accounts for a modest amount of the variability in use of health services.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Effectiveness and duration of intramuscular antimotion sickness medications.

Motion sickness inhibits gastric motility, making the oral route ineffective for medications. The intramuscular route is an effective alternative. The rotating chair was used to produce the M 111 level of motion sickness on the Graybiel Symptom Scale. The intramuscular medications given 30 minutes before rotation were compared with placebo (saline, 1 mL) for effectiveness and duration in increasing the number of tolerated head movements. Average placebo number of head movements was 294. Promethazine 25 mg increased head movements by 78% (P < .05), with a duration of 12 hours. Scopolamine 0.2 mg increased head movements by 91% (P < .05), with a duration of 4 hours. The effect of caffeine 250 mg and ephedrine 25 mg was not significant. When combined with scopolamine, ephedrine produced an 32% additive effect. Scopolamine 0.08 mg, 0.1 mg, and 0.2 mg and also promethazine 12.5 mg and 25 mg were significant (P < .05). Promethazine appears to be the drug of choice for intramuscular use because of a longer duration and a high level of effectiveness. Scopolamine was of high effectiveness, but had a duration of 4 hours. It was eight times as potent by the intramuscular as by the oral route.

Caffeine↗
PubMed1991

Effects of ginger on motion sickness susceptibility and gastric function.

This study was designed to evaluate the antimotion sickness activity of ginger root (Zingiber officinale) and to characterize the effects of ginger on gastric function. Twenty-eight human volunteers participated in the project. Subjects made timed head movements in a rotating chair until they reached an endpoint of motion sickness short of vomiting (malaise III or M-III). Each subject was tested with either ginger or scopolamine and a placebo. A substance was judged to possess antimotion sickness activity if it allowed a greater number of head movements compared to placebo control. Gastric emptying of a liquid was measured by nuclear medicine techniques in normal and motion sick subjects. Gastric electrical activity was monitored by cutaneous (surface) electrodes positioned over the abdominal area. Powder ginger (whole root, 500 or 1,000 mg) or fresh ginger root (1,000 mg) provided no protection against motion sickness. In contrast, subjects performed an average of 147.5 more head movements (p less than 0.01) after scopolamine (0.6 mg p.o.) than after placebo. The rate of gastric emptying was significantly (p less than 0.05) slowed when tested immediately after M-III but was inhibited less when tested 15 min after M-III. Powdered ginger (500 mg) had no effect on gastric emptying in normal or motion-sick subjects. Gastric motility was also changed during motion sickness. The frequency of the electrogastrogram (EGG) was increased after M-III (tachygastria) and the normal increase in EGG amplitude after liquid ingestion was reduced in motion sick subjects. Although powdered ginger (500 mg) partially inhibited tachygastria in motion sickness, it did not enhance the EGG amplitude in motion sick subjects. We conclude that ginger does not possess antimotion sickness activity, nor does it significantly alter gastric function during motion sickness.

Adolescent↗
PubMed1990

Referral issues in psychotherapy and psychoanalysis.

The authors consider the complex decisions involved in the initial consultation of a person looking for treatment when this person must be referred to a professional colleague. They explore the way decisions are made in the referral processes and the complex practical and transference-countertransference issues that arise at the outset and whenever second opinions are sought during an ongoing psychotherapy. They present four clinical examples in varying detail to emphasize how readily misunderstandings can develop when even experienced consultants are not sufficiently alert to the complex conscious and unconscious motives and messages being expressed in the exchanges. They make recommendations on how to conceptualize and respond to them.

Countertransference↗
PubMed1990

Therapeutic effects of antimotion sickness medications on the secondary symptoms of motion sickness.

In addition to nausea and vomiting, motion sickness involves slowing of brain waves, loss of performance, inhibition of gastric motility and the Sopite Syndrome. The therapeutic effects of antimotion sickness drugs on these reactions were evaluated. The subjects were rotated to the M-III end-point of motion sickness. Intramuscular (IM) medications were then administered. Side effects before and after rotation were reported on the Cornell Medical Index. Brain waves were recorded on a Grass Model 6 Electroencephalograph (EEG), and gastric emptying was studied after an oral dose of 1 mCi Technetium 99m DTPA in 10 oz. isotonic saline. An increase in dizziness and drowsiness was reported with placebo after rotation. This was not prevented by IM scopolamine 0.1 mg or ephedrine 25 mg. EEG recordings indicated a slowing of alpha waves with some thea and delta waves from the frontal areas after rotation. IM ephedrine and dimenhydrinate counteracted the slowing while 0.3 mg scopolamine had an additive effect. Alterations of performance on the pursuit meter correlated with the brain wave changes. Gastric emptying was restored by IM metoclopramide. Ephedrine IM but not scopolamine is effective for some of the secondary effects of motion sickness after it is established.

Adolescent↗
PubMed1990

Differential effects of scopolamine and amphetamine on microcomputer-based performance tests.

Scopolamine (1.0 mg) and d-amphetamine (10 mg) were administered alone and in combination to 16 subjects (medical students), randomly assigned to testing sessions in a fully crossed-over (Latin square) within-subjects design. After being practiced to stability, 9 performance tests from a menu of portable microcomputer-based tests were administered double-blind over 4 weekly treatments (including a placebo). Differential effects of drugs on performance were found. Motor and perceptual speed tests appeared enhanced by d-amphetamine and not degraded by scopolamine. Two of the five cognitive tests showed reductions with scopolamine. The findings are discussed in connection with using a menu of performance tests that can have diagnostic significance for assessment of drug treatments. The effects of scopolamine in this study and others are considered in terms of a model which implies that magnitude of performance deficit depends on performance type (cognitive, motor, self-report) and dosage level. Applying the model, we offer the following summary: below 0.15 mg scopolamine is without any effect; below 0.50 mg, the effect is limited, but can be revealed by some sensitive, complex performance tests and self-report; above 1.0 mg, the effect is likely to impact on operational efficiency.

Administration, Oral↗
PubMed1989

The effect of intravenous nutrition on muscle mass and exercise capacity in perioperative patients.

This study was undertaken to compare the efficacy of four different types of perioperative intravenous nutritional support. Fifty-five patients undergoing routine major surgery were studied. They were prospectively assigned to one of four study groups. Group 1 received formal total parenteral nutrition (90 g amino acids, 3,000 calories as glucose, per day); Group 2, 100 g glucose per day; Group 3, 90 g amino acids per day; and Group 4, peripheral parenteral nutrition (90 g amino acids plus 1,600 calories, 60 percent as fat per day). Group 1 was maintained on therapy for 3 weeks and the other groups for 8 days. Nitrogen balance, maintenance of body cell mass, serum albumin levels, and maintenance of exercise capacity were measured. Patients receiving peripheral parenteral nutrition maintained their nutritional parameters, as did those receiving total parenteral nutrition. These infusions were both markedly superior to those receiving glucose alone or those receiving amino acids alone. Nitrogen balance was not correlated with maintenance of function, but maintenance of body cell mass was correlated with maintenance of exercise capacity (r = 0.66, p less than or equal to 0.01). We conclude that perioperative peripheral parenteral nutrition, in contradistinction to hypocaloric infusions of glucose or amino acids, is capable of maintaining postoperative muscle mass and function close to preoperative levels after major surgery, and in situations of relatively mild surgical stress, approaches the efficacy of total parenteral nutrition in this regard. A significant correlation exists between changes in body cell mass determined from isotope dilution and changes in the exercise capacity of large muscle masses.

Adult↗
PubMed1989

Electrogastrograms during motion sickness in fasted and fed subjects.

Seven human volunteers were subjected to stressful Coriolis stimulation (rotating chair) either during the fasted state or following the ingestion of yogurt (6 oz). Subjects tested after yogurt reached a Malaise-III (M-III) endpoint of motion sickness after significantly (p less than 0.01) fewer head movements than subjects tested in the fasted state. Surface electrogastrogram (EGG) recordings at M-III were similar for both dietary states and consisted of a brief period of tachygastria, followed by a period of low amplitude EGG waves. Ingestion of yogurt enhanced susceptibility to motion sickness but did not affect the associated pattern of EGG.

Adolescent↗