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Biomedical subjects

C Lowery

Publications and source records attributed to C Lowery.

At least 19 recordsLinked to original sources
PubMed2003

[New perspectives in intrauterine surveillance with the fetal magnetoencephalogram].

PURPOSE: Despite intensive research and surveillance up to now one has failed to reduce cerebral handicaps in newborn. Fetal heart rate tracing (CTG) and Doppler have reduced the number of subpartal severe asphyxia and fetal death. But, 90% of cerebral damage is a result of antepartal problems. Thus only 10% can be avoided by intensive surveillance during labor. Detection of antenatal cerebral injury is a rare case and its impact on later fetal life can only be estimated. Insight in fetal neuronal function is not possible. Factors and time pattern determining fetal cerebral injury are thus not known. This publication explains a new system with whom one might be able to get more insight in cerebral wellbeing during the fetal intrauterine life. METHODS AND RESULTS: A new diagnostic approach is set up by recording fetal magnet encephalographic signals (fMEG) thus offering the opportunity to detect fetal brain function. An array which was especially designed to fit to the pregnant body consists of 151 sensors which are able to record the fMEG. Clinical testing is performed in the moment at the UAMS in Little Rock, Arkansas in Cooperation with the Institutes for Medical Psychology and the Frauenklinik in Tiibingen. First results and arising questions are published. CONCLUSION: With this new system a deeper insight into the fetal neuronal development and fetal wellbeing during pregnancy might be achieved thus reforming the fetal surveillance in the 21st century.

Brain↗
PubMed2003

Analysis of uterine contractions: a dynamical approach.

The development of suitable techniques for quantifying mechanical and electrophysiological aspects of uterine contractions has been an active area of research. The uterus is a physiological system consisting of a large number of interacting muscle cells. The activity of these cells evolves with time, a trait characteristic of a dynamical system. While such complex physiological systems are non-linear by their very nature, whether this non-linearity is exhibited in the external recording is far from trivial. Traditional techniques such as spectral analysis have been used in the past, but these techniques implicitly assume that the process generating the contractions is linear and hence may be biased. In this tutorial review, a systematic approach using a hierarchy of surrogate algorithms is used to determine the nature of the process generating the contractions produced during labor. The results reveal that uterine contractions are probably generated by non-linear processes. The contraction segments were obtained through simultaneous recordings of the electrical and magnetic signals corresponding to the electrophysiological activity of the uterus and then analyzed. The electrical activity was recorded by placement of non-invasive electrodes onto the maternal abdomen and magnetic activity was recorded non-invasively using a superconducting quantum interference device (SQUID).

Algorithms↗
PubMed2001

Successful PCR amplification of genomic DNA from Cryptosporidium parvum oocysts extracted from a human faecal sample: a rapid and simple method suited for outbreak analysis.

A method to extract genomic DNA from oocysts of Cryptosporidium parvum in human faecal material was developed and consisted of a simple alkali wash, freeze/boil technique. This method was simple, quick, sensitive, inexpensive and resulted in the production of genomic DNA which was free of PCR inhibitors and as such was a suitable template for the detection of C. parvum by various PCR amplification targets.

Animals↗
PubMed1994

Beliefs about condoms and their association with intentions to use condoms among youths in detention.

PURPOSE: Youths in detention have been identified as a high-risk group for AIDS. To help inform AIDS-prevention efforts targeted for these youths, we surveyed youths in detention regarding their sexual behaviors, beliefs about condoms, intentions to use condoms, and actual condom use. We examined race and gender differences in these beliefs and behaviors, and we studied the relationship of these beliefs to condom-use intentions. METHODS: Questionnaires were administered to a sample of 201 youths in detention who were, on average, 16 years old. The sample was stratified on gender and race (African-American and white), with approximately equal numbers in each group. RESULTS: The results indicate that these youths had engaged in behaviors that put them at high risk of acquired immunodeficiency syndrome (AIDS) and other sexually transmitted diseases. Although they used condoms somewhat more consistently with casual partners than with their steady partners, the majority did not use condoms consistently with either partner type. Very few race or gender differences were found with regard to condom use, intentions to use condoms, or beliefs about the consequences of using condoms. Beliefs associated with intentions to use condoms with steady partners included protection against sexually transmitted diseases (STDs), and the beliefs that condoms reduce pleasure, are artificial, unromantic, and interrupt sex. In contrast, only the belief that condoms prevent pregnancy was related to intentions to use condoms with casual partners. CONCLUSION: The results suggest that interventions targeted at African-American and white males and females in detention need not differ greatly in content as long as they include the most salient concerns of each group; that interventions include content on the two protective benefits of condom use (pregnancy and STD prevention), as well as on how to minimize the perceived negative aspects of condom use; that they stress the need for condom use with steady as well as casual partners; and that they stress that anal intercourse is especially risky with regard to AIDS transmission.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Metabolic activation and bacterial mutagenicity of aflatoxin B1 in two different test systems.

The metabolism of aflatoxin B1 (AFB1) by liver post-mitochondrial supernatant fraction from phenobarbitone treated male albino rats in liquid suspension and soft-agar plate incorporation bacterial mutation assay systems has been studied. The AFB1 concentration used was in the range of those added to bacterial mutagenicity tests with this mycotoxin. Three oxidative metabolites of AFB1 viz the Tris derivative of AFB1 8,9-diol (derived from the 8,9-epoxide), aflatoxin Q1 (AFQ1) and M1 (AFM1) were observed. The metabolite profile and time course of formation were qualitatively similar in both assay systems. The rate and overall formation of metabolites in the soft-agar system was approximately one half that in the liquid suspension system which was reflected in decreased AFB1 induced bacterial mutation in the former system. The AFB1 metabolite profile in these in vitro systems did not mirror completely the reported in vivo profile seen in the rat, as aflatoxin P1 (AFP1) and a glutathione conjugate were not detected. No evidence was found for a prolongation of metabolism in the soft-agar system.

Aflatoxin B1↗
PubMed1981

The effects of albumin-bound unsaturated fatty acids on platelets.

Unsaturated fatty acids (FA) were bound to human albumin in a molar ratio of 2 and were then added to platelet-rich plasma (PRP), increasing the total FA concentration by 1 mM. Separate FA and FA paired with di-homo-gamma-linolenic acid (DHLA) and arachidonic acid (AA), respectively, were incubated with PRP for 5 and 90 min, and platelet aggregation and platelet factor 3 (PF3) activity were measured. DHLA inhibited adenosine-diphosphate- and collagen-induced platelet aggregation after 5 min, an effect which was enhanced after 90 min. The effects of AA, which stimulated platelet aggregation and increased PF3 activity, were partially counteracted by DHLA after 90 min. When linoleic acid and AA were incubated with PRP in equimolar concentrations for 90 min, an inhibition of collagen-induced platelet aggregation was observed which was not observed after incubation with these FA separately. This study indicates that exogenous albumin-bound AA and DHLA may be used directly by the platelet cyclo-oxygenase pathway before significant incorporation into the platelet phospholipids has occurred.

Adolescent↗
PubMed1981

For parents and children only: a parent-child educational library.

A Parent-Child Education Library was developed at a children's hospital to help fill the gap in communication between staff and families. The written materials supplement the staff's verbal explanations. Materials include both medical and other child-related, educational topics. The library was approved by the medical staff and is funded by donations. Counseling has become an appropriate adjunct to the library, as parents and/or children share their problems and feelings. The library is a service provided by the Child Life Program.

Adult↗
PubMed1981

Practolol metabolism. III. Irreversible binding of [14C]practolol metabolite(s) to mammalian liver microsomes.

The irreversible binding of [14C]practolol metabolites to mammalian liver microsomes was studied in vitro. Binding occurred by covalent linkage to amino acids of microsomal proteins. The binding reaction was dependent on oxygen, NADPH, reaction time, microsomal protein content and substrate concentration and was inhibited by carbon monoxide, glutathione and albumin. Albumin inhibition resulted in the binding of reactive metabolite(s) to this serum protein. Hamster (Syrian) liver microsomes had the highest rate of binding and 3-hydroxypractolol formation and marmoset the lowest. The reduced binding of [acetyl-14C]practolol compared to [phenyl-14C]practolol to hamster liver microsomes, but not rat, indicated that metabolites with and without the acetyl grouping were bound in this species. The binding of [14C]desacetylpractolol to hamster liver microsomes was greater than the binding of practolol. Sodium fluoride caused both an increase and a decrease of practolol binding to microsomes from pooled hamster livers, whereas there was a consistent increases in binding to microsomes from individual hamster livers. The collective data indicate that electrophilic metabolites of practolol, possibly N-hydroxylation of the acetyl-amino grouping are formed by the microsomal cytochrome P-450-dependent drug metabolizing enzyme system. These metabolites can react irreversibly with tissue and serum proteins which could be sufficiently altered to be recognized as antigens.

Animals↗
PubMed1979

Triglyceride lipase activity and human platelets.

The activity of triglyceride lipases in human postheparin plasma is significantly higher in platelet rich than platelet poor plasma. This holds for total activity, lipoprotein lipase (LPL) activity, and hepatic triglyceride lipase (H-TGL) activity. Gel filtration of platelet rich postheparin plasma on Sepharose 2 B will separate platelets from triglyceride lipase activity. The very small triglyceride lipase activity of isolated platelets is inhibited by 1.0 M NaCl, slightly inhibited by specific antibody to hepatic lipase, and not influenced by specific antibody to lipoprotein lipase.

Blood Platelets↗
PubMed1977

Characterization of the nucleoside triphosphate phosphohydrolase (ATPase) activity of RNA synthesi termination factor p. I. Enzymatic properties and effects of inhibitors.

The purification of p protein to homogeneity from Escherichia coli has shown that its RNA-dependent ATPase activity is physically inseparable from its termination activity. The biochemical properties of pATPase have been studied using poly(C) as the activating RNA. This reaction is stimulated by Mg2+ ions and Mn2+ ions and is prevented by excess EDTA; it is not stimulated by Ca2+ ions. The reaction is not affected by a Zn2+ ion chelator and is inhibited by 1 mM Zn2+. With Mg2+ present, the activity is essentially constant from pH 7 to pH 9.7. pATPase is sensitive to p-hydroxymercuribenzoate and to N-ethylmaleimide. All four ribonucleoside triphosphates are hydrolyzed by p action. ATP has the lowest Km (0.009 mM), while CTP has the highest Vmax. In a mixture containing all four nucleoside triphosphates at a concentration of 0.4 mM, p shows no strong preference for any one of the substrates. The response of p ATPase to a variety of inhibitors of other ATPases and GTPases and of transcription has been studied. Of the compounds tested, aurintricarboxylic acid, an inhibitor of protein-nucleic acid interactions, was found to be a potent inhibitor of p ATPase, while rifampicin and heparin had no effect. pATPase showed partial sensitivity to thiostrepton, fusidic acid, Dio 9, and sodium azide.

Adenosine Triphosphatases↗
PubMed1977

Characterization of the nucleoside triphosphate phosphohydrolase (ATPase) activity of RNA synthesis termination factor p. II. Influence of synthetic RNA homopolymers and random copolymers on the reaction.

The ability of various kinds of RNA molecules to activate the ATP hydrolysis reaction catalyzed by the p transcription termination factor from Escherichia coli has been studied. The most active RNA polymers are those containing cytidylate residues and very little ordered structure. Free poly(C) is the most active homopolymer; it is 45 times more active than poly(U), which is the only non-cytidine containing RNA that has detectable activity. Poly(C) has no activity when complexed with poly(I) or when the chain lengths are shorter than 22 nucleotides long. Although cytidylate residues are important they need not be frequent; a random copolymer of uridine and cytidine nucleotides with as few as 1 cytidylate residue out of 20 is as active as poly(C). The extent of activation with poly(C) depends on the ratio of p to poly(C). Poly(C) becomes saturated with p at a ratio of 1.8 ng of p/pmol poly(C), which is equivalent to one p monomer/27 nucleotides. A further increase in this ratio leads to a reduction in p activity. Decreasing the length of the poly(C) does not alter the observed saturation value but does decrease the rate of ATP hydrolysis when the RNA is in excess. The possible relevance of these results to p termination activity is discussed.

Adenosine Triphosphatases↗
PubMed1975

Transcription termination factor rho activity is altered in Escherichia coli with suA gene mutations.

Rho factor has been purified from a strain of E. coli containing the Su78 mutation in the suA gene and assayed in another strain with an amber mutation in the suA gene. The rho from the Su78 mutant strain is present in normal amounts but has altered termination function; it does not terminate transcription at some sites that are recognized effectively by the rho factor from the isogenic wild-type strain. Rho in cells with an amber mutation in the suA gene has been assayed by its RNA-dependent ATPase activity. Extracts of cells of this strain have only 9% as much of this rho activity as extracts of cells of the isogenic wild-type strain. These results suggest that rho is the product of the suA gene. Since mutations in the suA gene are known to decrease polar effects of mutations in other genes, it is also suggested that rho factor is at least partially responsible for polar effects.

Bacterial Proteins↗
PubMedDate not supplied

Subtotal calcanectomy for the treatment of large heel ulceration and calcaneal osteomyelitis in the diabetic patient.

Diabetic, neuropathic patients are often at risk for ulceration. Those that are temporarily or permanently limited in ambulation and restricted to a supine position are over time very susceptible to heel decubiti. Twelve patients with heel ulceration and calcaneal osteomyelitis who underwent subtotal calcanectomy are presented. Aggressive debridement of all nonviable tissue was coupled with a thorough antibiotic course in all cases. Ten of the 12 were completely healed at follow-up of 13 months. Two patients died of cardiac complications unrelated to their surgery. Postoperatively, the 10 patients were placed in an ankle-foot orthosis combined with a custom-molded shoe. All patients who were ambulatory preoperatively were able to resume their function after surgery. Subtotal calcanectomy is a relatively simple procedure to perform. In the presence of adequate vasculature, it is a good alternative to below-the-knee amputation and the accompanying sequelae.

Adult↗