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Biomedical subjects

A Fleming

Publications and source records attributed to A Fleming.

At least 37 records · Page 2Linked to original sources
PubMed1998

Embryonic folate metabolism and mouse neural tube defects.

Folic acid prevents 70 percent of human neural tube defects (NTDs) but its mode of action is unclear. The deoxyuridine suppression test detects disturbance of folate metabolism in homozygous splotch (Pax3) mouse embryos that are developing NTDs in vitro. Excessive incorporation of [3H]thymidine in splotch embryos indicates a metabolic deficiency in the supply of folate for the biosynthesis of pyrimidine. Exogenous folic acid and thymidine both correct the biosynthetic defect and prevent some NTDs in splotch homozygotes, whereas methionine has an exacerbating effect. These data support a direct normalization of neurulation by folic acid in humans and suggest a metabolic basis for folate action.

Animals↗
PubMed1997

Requirements for Epstein-Barr nuclear antigen 1 (EBNA1)-induced permanganate sensitivity of the epstein-barr virus latent origin of DNA replication.

Epstein-Barr nuclear antigen 1 (EBNA1) activates DNA replication from the Epstein-Barr virus latent origin of DNA replication, oriP. EBNA1 binds cooperatively to four recognition sites in the dyad symmetry (DS) element of oriP, causing alterations in the origin DNA structure, which can be detected by the increased sensitivity of one Thy residue in two of the binding sites to permanganate oxidation. To better understand the significance of this EBNA1-induced origin distortion, we have investigated the DNA sequence and EBNA1 amino acid requirements for permanganate sensitivity. We have shown that the EBNA1 DNA binding and dimerization domains are sufficient to induce permanganate sensitivity and that amino acids 463-467, which form an extended chain that travels along the minor groove of the EBNA1 recognition site, play an important role in generating the DNA distortion. The EBNA1-induced permanganate sensitivity is independent of cooperative interactions between EBNA1 molecules on the origin and requires a specific sequence within the EBNA1 binding site. Using synthetic EBNA1 binding sites, we found that the inversion of a single AT base pair in the EBNA1 recognition sequence is sufficient to confer EBNA1-induced permanganate sensitivity. These studies indicate that permanganate oxidation can detect very minor alterations in DNA structure.

Binding Sites↗
PubMed1997

Mechanisms of normal and abnormal neurulation: evidence from embryo culture studies.

The method of whole embryo culture has been used extensively in analyzing the mechanisms underlying formation of the mammalian neural tube. These studies have provided insight into the cell lineage of the various tissues that comprise the neurulation stage embryo, the role of microfilaments, extracellular matrix and cell proliferation in the morphogenetic events of neural tube closure and the action of specific genes and gene products in establishment of the nervous system. This information is of considerable importance not only as a means of elucidating the processes of normal embryogenesis but also to shed light on the pathogenesis of important human birth defects.

Animals↗
PubMed1996

Latissimus dorsi muscle: assessment of stimulation after cardiomyoplasty with Doppler US tissue imaging.

PURPOSE: To evaluate Doppler ultrasound (US) tissue imaging for assessment of stimulated skeletal muscle contraction. MATERIALS AND METHODS: Seven patients were studied after left latissimus dorsi cardiomyoplasty. Myograft contraction programmed on alternate cardiac cycles was assessed with Doppler US tissue imaging. Beat-to-beat variation in inferior wall motion was assessed by examining peak myograft velocities during 10 muscle-assisted and 10 nonassisted cardiac cycles. The temporal relationship between electrostimulation and myograft contraction, changes in cardiac geometry, and the effect of alterations in stimulation voltage and muscle synchronization were assessed. RESULTS: Significant beat-to-beat variation in velocity profile could be detected in the proximal myograft in six patients (P < .05). Potentiation of infero-posterior wall motion was measurable in five patients (mean peak systolic wall velocity: nonassisted, 2.5 cm.sec-1 +/- 0.5 [standard deviation]; assisted, 7.8 cm.sec-1 +/- 6.3). The response between stimulation voltage and inferoposterior wall velocity was sigmoid. CONCLUSION: Doppler US tissue imaging depicted the effects of myostimulator programming on muscle contraction and ventricular wall motion.

Cardiomyoplasty↗
PubMed1995

National Medical Association Surgical Section position paper on violence prevention. A resolution of trauma surgeons caring for victims of violence.

The epidemic of intentional injury continues to be a leading cause of premature death in America. The ravages of violence are particularly devastating within the minority community. With this position paper from the Surgical Section of the National Medical Association (the country's oldest and largest organization of minority physicians), a group of trauma surgeons and surgical intensivists resolve to focus on underused violence prevention opportunities and to extend their spheres of influence beyond the walls of their institutions and emphasize violence prevention activities.

Humans↗
PubMed1995

Clinical evaluation of continuous noninvasive blood pressure monitoring: accuracy and tracking capabilities.

A continuous, noninvasive device for blood pressure measurement using pulse transit time has been recently introduced. We compared blood pressure measurement determined using this device with simultaneous invasive blood pressure measurements in 35 patients undergoing general endotracheal anesthesia. Data were analyzed for accuracy and tracking ability of the noninvasive technique, and for frequency of unavailable pressure measurements by each method. A total of 25,133 measurements of systolic pressure, diastolic pressure, and mean arterial pressure (MAP) by each method were collected for comparison from 35 patients. Accuracy was expressed by reporting mean bias (invasive pressure minus noninvasive pressure) and limits of agreement between the two measurements. After correction for the offset found when measuring invasive and oscillometric methods of arterial pressure measurement, the mean biases for systolic, diastolic, and mean pressures by the pulse wave method were -0.37 mm Hg, -0.01 mm Hg, and -0.05 mm Hg, respectively (p < 0.001). The limits of agreement were: -29.0 to 28.2 mm Hg, -14.9 to 14.8 mm Hg, and -19.1 to 19.0 mm Hg, respectively (95% confidence intervals). When blood pressure measured invasively changed over time by more than 10 mm Hg, the noninvasive technique accurately tracked the direction of change 67% of the time. During the entire study, 3.2% of the invasive measurements were unavailable and 12.9% of the noninvasive measurements were unavailable. The continuous noninvasive monitoring technique is not of sufficient accuracy to replace direct invasive measurement of arterial blood pressure, owing to relatively wide limits of agreement between the two methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure Determination↗
PubMed1995

Skeletal muscle contraction in healthy volunteers: assessment with Doppler tissue imaging.

PURPOSE: To evaluate Doppler tissue imaging (DTI) in the measurement and characterization of skeletal muscle movement and contraction. MATERIALS AND METHODS: Five healthy male subjects were examined with a commercially available ultrasound imaging unit modified for DTI. Velocities of the rectus femoris and gastrocnemius-soleus muscle motion were measured during the patellar and ankle reflexes, respectively. Velocity profiles were analyzed after digitization of the DTI images. Time to peak velocity, velocity range, and relaxation time were examined in each case over three contractions. For reflex contractions, reproducibility was examined by determining the latency period, area under the velocity curve, and duration of contraction for each of five consecutive reflexes. RESULTS: Isotonic muscle contraction could be distinguished from passive movement by a higher tissue velocity range, by a more rapid initial acceleration slope, and by the velocity differential across the muscle. The intensity and duration of the contraction and plateau and relaxation phases of isotonic contraction could be measured in all muscle groups. CONCLUSION: DTI provides detailed information about the dynamics of skeletal muscle contraction.

Adult↗
PubMed1995

[Doppler tissue imaging: current status and future prospects].

Colour Doppler myocardial imaging is a new technique which allows the visualization in the colour Doppler of myocardial tissues, instead of blood pool imaging. To permit the acquisition of this information some modifications are essential in the machine. The gain has to be reduced so that, firstly, the echoes from ventricular walls were similar to those from the blood pool. Secondly the Doppler velocity range has to be reduced to correspond to the normal velocity of the ventricular wall. These modifications allow the tissue echoes to pass the clutter filter and to be displayed in colour on the video screen. This technique may be able to evaluate the velocity of myocardial tissue, the acceleration and the strength within the myocardial wall with these maps, obtained by modifications in the software, called Velocity Map, Acceleration Map, Energy Map. The clinical applications of this technique are: 1) in the area of myocardial functions e.g.: measurements, volumes, diastolic functions; 2) in the area of myocardial ischemia e.g.: wall motion abnormalities, viability studies, perfusion with contrast agents, stress echo, infarct identification; 3) in the area of myocardial depolarisation e.g.: arrhythmias evaluation, ablation monitoring. Doppler tissue imaging in spite of good results obtained, needs a large clinical studies.

Coronary Disease↗
PubMed1994

Isolation of suppressors of temperature-sensitive folding mutations.

Mutations in the tailspike gene (gene 9) of Salmonella typhimurium phage P22 have been used to identify amino acid interactions during the folding of a polypeptide chain. Since temperature-sensitive folding (tsf) mutations cause folding defects in the P22 tailspike polypeptide chain, it is likely that mutants derived from these and correcting the original tsf defects (second-site intragenic suppressors) identify interactions during the folding pathway. We report the isolation and identification of second-site revertants to tsf mutants.

Bacteriophage P22↗
PubMed1994

Drug management of arthritis in the elderly.

Rheumatic disorders are common in the ageing population requiring the use of DMARDs and immunosuppressive therapy as with younger patients. Indications for therapy are approximately the same in both groups, but toxic side-effects are probably more common in the elderly necessitating close supervision of indications and drug requirements. Local injection techniques The practice of local injection of corticosteroid in musculo-skeletal disorders is widespread. The literature on comparative efficacy between different preparations is scanty. These techniques can give significant relief in rheumatoid arthritis, osteoarthritis, sero negative arthropathies, crystal induced arthritis and many soft tissue lesions. Severe joint and soft tissue lesions are common in the elderly. In these patients even a small loss of physical function may have a markedly detrimental effect on independence. Such lesions should therefore be actively sought and vigorously treated. Often a simple, rapidly acting, local corticosteroid injection is preferable to a prolonged course of either NSAIDs or physiotherapy. In general, such injections should not be used if the diagnosis is uncertain, or there is any suspicion of infection, or if there has been a previous severe local reaction. Injections that are becoming too regular mean that the technique has not proved successful and other therapies should be sought. In performing the injections, antisepsis should be scrupulous and a 'no-touch' technique used. Accuracy of needle placement is necessary for good results. Injections should not be given against pressure as this generally means incorrect sitting. Some systemic absorption does occur.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Periodontal procedures to enhance esthetics.

Dentistry today can provide excellent esthetics for the patient. Periodontal procedures have transcended the era where the treatment and scope are limited to pocket reduction and disease control. Periodontal plastic surgery will prove to be an excellent adjunct when properly applied in conjunction to elective esthetic dentistry.

Dental Implantation↗
PubMed1993

The Glasgow Coma Scale and prognosis in gunshot wounds to the brain.

To determine which factors predict survival in patients with gunshot wounds to the brain, 192 patients who had intracranial injury demonstrated on computed tomographic (CT) scanning were retrospectively reviewed. Glasgow Coma Scale (GCS) scores on admission seemed to be the most important factor in predicting survival. Age, the presence of extruded brain, and use of a shotgun could not be shown to be factors independent of admission GCS score. Findings on CT scans (single lobe vs. multilobe involvement) helped to predict survival only in patients with GCS scores 5-13. The mortality rate was 35%. Among survivors 18% had brain-related long-term disability, and an additional 27% had long-term disability related to associated eye injury.

Adolescent↗
PubMed1993

Open laparoscopic cholecystectomy in pregnancy.

Since the introduction of laparoscopic cholecystectomy in 1989, surgeons worldwide have become familiar with the basic techniques involved. Pregnancy has previously been considered an absolute contraindication to laparoscopic cholecystectomy; however, we present three cases of laparoscopic cholecystectomy in pregnancy. If conservative management fails, this method, far from being absolutely contraindicated, should be the procedure of choice in pregnancy, as it has already become in nonpregnant patients. Transvaginal ultrasound allows continuous monitoring of fetal heart rate in all stages of pregnancy after the 7th week. The open (Hasson) technique should be strongly considered if accidental uterine puncture and potential fetal damage are to be avoided.

Adolescent↗