Search PubMed⌕ Search

Biomedical subjects

J Weaver

Publications and source records attributed to J Weaver.

At least 91 records · Page 5Linked to original sources
PubMed1978

Electrostatic complexes of mitomycin C with nucleic acids and polyanions.

Reductively activated mitomycin C exhibits strong, non-covalent electrostatic binding to polyanions such as polyvinylsulfate and polyphosphate. The protonated C-2 amino group generated by the reduction is most likely responsible for this type of interaction. At moderate drug and salt concentrations only covalent binding to nucleic acids is observable. This is shown to be guanine-specific in DNA for the first time, as well as in synthetic polyribo- and polydeoxyribonucleotides at 10--20 times higher binding levels than previously tested. At higher mitomycin C concentration, however, strong non-covalent electrostatic binding to nucleic acids also occurs, resulting in a binding ratio up to 1 mol drug bound per mol mononucleotide, although this non-specific binding is relatively inhibited compared to polyvinylsulfate. Salts also have an inhibitory effect on the non-specific binding to nucleic acids. A series of mitomycin derivatives were compared for their binding and cross-linking abilities using DNA as substrate, with the following results: (a) the presence of a basic nitrogen . funtion at C-2 promotes binding, both covalent and electrostatic, presumably by kinetically facilitating the approach between positively charged nitrogen and DNA. (b) The aziridine ring is the major covalent binding site, indispensable for crosslinking and determines the guanine-specificity of the binding.

Anions↗
PubMed1976

Structural aberrations of the long arm of chromosome no. 22. Report fo a family with translocation t(11;22) (q25;q11).

A chromosomal translocation t(11;22) (q25q11) is described in a family. Four members, in two generations, had the same translocation but showed phenotypic variation. Case reports of chromosome aberrations involving the long arm of chromosome 22 associated with and without chronic myeloid leukemia (CML) are reviewed. It appears that the distal segment of the long arm or chromosome 22 is either translocated or deleted, resulting in congenital anomalies, presumably due to chromosome imbalance. In other instances, a specific breakpoint on 22q results in the origin of Philadelphia chromosome (Ph1) associated with CML.

Abnormalities, Multiple↗
PubMedDate not supplied

Prehospital refusal-of-transport policies: adequate legal protection?

OBJECTIVES: To determine the percentage of EMS systems utilizing formal refusal-of-transport policies and to evaluate the adequacy of these policies as a means of protection against potential litigation. METHODS: A scripted, closed-ended, 17-question survey was administered to EMS representatives in the 100 most heavily populated U.S. cities. This survey focused on four main areas: utilization of formal refusal-of-transport policies, criteria for the establishment of patient competence, supervision of field personnel while carrying out refusal-of-transport policies, and documentation requirements. RESULTS: Eighty-six of 100 (86%) EMS representatives participated. Ten (10%) were unreachable, and four (4%) refused to participate. Seventy-eight of the 86 EMS services (91%) utilized formal refusal-of-transport policies. Eighty-three percent (65 of 78) mandated establishment of patient competence. Orientation to person, place, and time was utilized by 97% (63 of 65), lack of alcohol intoxication by 66% (43 of 65), comprehension of the nature of the medical condition by 58% (38 of 65), comprehension of the risks and benefits of treatment by 48% (31 of 65), clear speech by 42% (27 of 65), and lack of head trauma by 3% (2 of 65). Age-appropriate behavior, emotional control, and no loss of consciousness were each employed in 2% (1 of 65) of these policies. Fifteen percent of the 65 policies studied required contact with a physician, 5% with a supervisor, and 1% with the police. Ninety-nine percent of these policies required the patient to sign a statement of refusal, while 81% required documentation of vital signs. Only 32% of these policies contain all of the elements recommended in the medical and legal literature. CONCLUSION: The majority of EMS systems surveyed have adopted formal policies to guide field personnel in the management of patient refusals. Fewer than a third of these policies contain all of the elements shown to be protective against legal challenge.

Humans↗
PubMedDate not supplied

Geometrical considerations for Compton scatter densitometry.

The determination of the physical density by Compton scatter densitometry is dependent upon the geometry used for the measurement. The diameter of the sample, the density range, and the scattering volume size and shape influence the relative electron density values obtained by such a system. This work presents the results of an experimental analysis of these parameters in which the importance of each is evaluated for samples of known density. A bias in the computed Compton density, due to multiple scattering and attenuation, is defined; and an expression relating the density bias to these geometrical parameters is presented. The importance of applying corrections to the computed physical density for samples of large diameter and/or high density (cortical bone tissue and large diameter cancellous bone tissue) is discussed.

Bone and Bones↗
PubMedDate not supplied

The effect of electronic dental anesthesia on behavior during local anesthetic injection in the young, sedated dental patient.

PURPOSE: The purpose of this study was to evaluate the effectiveness of the 3M Electronic Dental Anesthesia (EDA) finger electrode on reducing sedated patient responsiveness during local anesthesia administration. METHODS: Thirty patients between the ages of 24 to 48 months, ASA I, and in need of treatment of maxillary anterior teeth using local anesthesia were used in this study. Each of the patients received chloral hydrate (CH) and hydroxyzine (50 mg/kg and 2 mg/kg, respectively). The patients were divided randomly in two groups. The experimental group received activated electronic dental anesthesia (AEDA) while the control group had a nonactive EDA (NAEDA). Physiological parameters were recorded and behavior was videotaped and rated using the Ohio State University Behavior Rating Scale. A repeated-measures ANOVA, Student's tests, and descriptive statistics were used. RESULTS: The results indicated that the heart rate and diastolic blood pressure of both groups were significantly affected as a function of time and dental procedures. A significant effect in the percent change of heart rate between groups was noted during local anesthetic injection with the NAEDA group having an increased heart rate. There was a higher occurrence of movement in the NAEDA compared to the AEDA. CONCLUSION: The EDA appears to be beneficial in reducing the discomfort, as judged by behavioral and physiologic observations, associated with local anesthetic administration in young sedated dental patients.

Analysis of Variance↗