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Biomedical subjects

D D Harrison

Publications and source records attributed to D D Harrison.

At least 55 records · Page 3Linked to original sources
PubMed1993

Endocervical brush versus cotton swab for obtaining cervical smears at a clinic. A cost comparison.

Use of the nylon endocervical brush has been shown to increase the proportion of Papanicolaou smears with endocervical cells in a variety of populations. Each endocervical brush is approximately 100 times more expensive than the cotton swab that has been used routinely for cervical cytology collection. We sought to determine prospectively whether the endocervical brush would be cost effective by reducing the need for repeat sampling due to Papanicolaou smears' lacking endocervical cells. Cervical cytology specimens showed no endocervical cells in 114 (20%) of 561 women sampled with a cotton swab and Ayre spatula. In contrast, 37 (7%) of 511 women sampled with the endocervical brush and Ayre spatula had no endocervical cells in their specimens. A cost analysis showed that at our clinic, where approximately 3,300 Papanicolaou smears are performed annually, annual savings of > $22,000 would be realized by use of endocervical brushes.

Adolescent↗
PubMed1988

An elucidation of factors influencing physicians' willingness to perform elective female sterilization.

When a woman requests sterilization, how does her physician decide whether to operate? To answer this question, we analyzed the responses of 341 gynecologists to a survey consisting of clinical vignettes using a new statistical technique, conjoint analysis. The patient factors found to be statistically significant (all P less than .00005), in order, were age, parity/timing, and race. Other significant factors (all P less than .05) were marital status, family income, and educational level. Within those factors, physicians were most willing to sterilize older, postpartum, parous, black, married, poor, or well-educated women. Groups of physicians analyzed by age, gender, race, practice locale, practice type, religion, and religiosity were remarkably similar in their ordering. By a separate analysis, physicians were more willing to sterilize a diabetic woman than a woman in good health. This study supports the conclusions that factors including age, parity, timing, race, and health influence some gynecologists' decisions to sterilize and that not all gynecologists are willing to sterilize all patients.

Age Factors↗
PubMed1983

Adhesive responses of fibroblast and neuroblastoma cells to substrata coated with polyvalent or monoclonal antibody to fibronectin.

Both polyvalent and hybridoma-produced antibodies to fibronectin (Fn) were used to 'map' the immunoaccessible subsets of cell surface fibronectin on virus-transformed murine fibroblast SVT2 and rat neuroblastoma B104 cells. As one approach to this end, attachment and spreading responses of cells were measured on tissue culture substrata coated with antibody or with plasma fibronectin to compare their adhesive responses. Both SVT2 and B104 cells adhere poorly to polyvalent anti-Fn-coated substrata over short time intervals, but within several hours changes occur which permit cells to attach and spread as well on anti-Fn as on Fn (post-adsorption of the anti-Fn with Fn also generates a maximal response). This adhesive response could be completely prevented by predigesting the cells with Flavobacterium heparanase, but not with chondroitinase ABC, indicating that the cell surface Fn responsible for antibody-mediated adhesion is associated with heparan sulfate proteoglycans on the cell surface. The compositions of the substratum-attached material (left bound after EGTA-mediated detachment of cells) from cells attaching to anti-Fn or Fn were analysed by SDS-PAGE and found to be identical within the same cell type for the two different substrata. Three hybridoma-produced antibodies, which recognize different determinants on Fn, generated different adhesive responses for SVT2 or B104 cells when adsorbed to the substratum. SVT2 cells adhered well to antibody no. 32-coated substrata but poorly to antibodies 92 or 136; on the other hand, B104 cells responded similarly to all three antibodies over short times of attachment but much better to no. 32 after a several hour incubation. These experiments indicate that (1) much of the cell surface fibronectin is complexed with heparan sulfate proteoglycan and is initially inaccessible to bind to polyvalent antibody on the substratum to promote adhesion; (2) the surface of neuroblastoma cells contains a fibronectin-like molecule which is important in their substratum adhesion; and (3) monoclonal antibodies are valuable tools in 'mapping' the orientation of cell surface molecules like fibronectin by measuring adhesive responses to antibody-coated substrata.

Animals↗
PubMed1983

Relaxation therapy: adjunctive therapy for the physician.

Relaxation therapy is one of the new modalities in the area of behavioral medicine which physicians may wish to use for tense patients as adjunctive to purely medical treatment. Efficacy of the specific therapy and patient compliance may be improved by use of relaxation therapy. This paper gives details on how to provide the basics in relaxation training. These techniques were used in a research program developed at Howard University Medical School. The beginning steps in controlled, relaxed breathing; progressive relaxation; autogenic training; and simple mental imagery are described. It is emphasized that time is required for the patient to acquire these skills. The skills are cumulative and, once learned, can lead to self-regulation and self-discipline to assist individuals in dealing with stress.

Humans↗
PubMed1979

Biofeedback and relaxation in blacks with hypertension: a preliminary study.

Previous studies show that stress increases blood pressure as a response to the sympathetic nervous system and that enhancement of parasympathetic activity promotes relaxation and lowers blood pressure. This paper is based on a preliminary study of 22 black subjects with a history of hypertension who were given biofeedback and relaxation training in the Biofeedback Laboratory at Howard University College of Medicine. The guided training consisted of eight weekly sessions using five instruments. Mean blood pressure (BP) was monitored in each session using a Stoelting BP Monitor. Data based on 10 characteristics (age, number of sessions, practice score, social readjustment scale, stress symptoms, systems review, initial and last systolic and diastolic BP) are analyzed and presented in five tables. Although differences between the initial and last readings of the systolic and diastolic BPs and during the test were observed, they were not statistically significant, probably due to small sample size. Analysis was also made by grouping the patients into three groups depending on the increase, decrease, or no change in BP. All patients demonstrated that the biofeedback training was beneficial in lowering the BP. These techniques should be incorporated into daily life to have lasting benefit.

Adult↗
PubMed1978

Fructokinase (Fraction III) of Pea Seeds.

A second fructokinase (EC 2.7.1.4) was obtained from pea seed (Pisum sativum L. var. Progress No. 9) extracts. The enzyme, termed fructokinase (fraction III), was specific for fructose and had little activity with glucose. With fructose concentrations above 0.25 millimolar, there was strong substrate inhibition at the optimum pH (8.0) and also at pH 6.6. The apparent K(m) values at pH 8.0 for fructose and glucose were 0.06 millimolar and 0.14 millimolar, respectively. The apparent K(m) for Mg adenosine 5'-triphosphate (MgATP) was 0.06 millimolar and excess MgATP was inhibitory. Mg(2+) was essential for activity but the enzyme was inhibited by excess Mg(2+) or ATP. Mg adenosine 5'-pyrophosphate was also inhibitory. Activity was stimulated by the addition of monovalent cations: of those tested K(+), Rb(+), and NH(4) (+) were the most effective. The possible role of fructokinase (fraction III) is discussed.

Journal Article↗
PubMed1977

Glucokinase of pea seeds.

1. Glucokinase (ATP : D-glucose 6-phosphotransferase, EC 2.7.1.2) was extracted from pea seeds and purified by fractionation with (NH4)2SO4 and chromatography on DEAE-cellulose and Sephadex. 2. The relative rates of phosphorylation of glucose, mannose and fructose (final concentration 5 mM) were 100, 64 and 11. 3. The Km for glucose of pea-seed glucokinase was 70 muM and the Km for mannose was 0.5 mM. The Km for fructose was much higher (30 mM). 4. Mg2+ ions were essential for activity. Mn2+ could partially replace Mg2+. 5. Enzyme activity was not inhibited by glucose 6-phosphate. A number of other metabolites had no effect on glucokinase activity. 6. Pea-seed glucokinase was inhibited by relatively low concentrations of ADP.

Adenosine Diphosphate↗
PubMed1977

Fructokinase (Fraction IV) of Pea Seeds.

A fructokinase (EC 2.7.1.4) was obtained from pea (Pisum sativum L.) seeds. This enzyme, termed fructokinase (fraction IV), was specific for fructose as substrate and had little activity with glucose or mannose. Excess fructose inhibited the enzyme at the optimum pH (8.2) but not at pH 6.6. MgATP was inhibitory at pH 6.6. The apparent Michaelis-Menten constants at pH 8.2 were 0.057 mm for fructose and 0.10 mm for MgATP. Mg(2+) ions were essential for activity; Mn(2+) could partially replace Mg(2+). Fructokinase (fraction IV) had a requirement for K(+) ions which could be substantially replaced by Rb(+) or NH(4) (+) but not by Na(+). The enzyme was inhibited by MgADP. The possible significance of fructokinase (fraction IV) in plant carbohydrate metabolism is discussed.

Journal Article↗
PubMedDate not supplied

Sitting biomechanics part I: review of the literature.

OBJECTIVE: To develop a new sitting spinal model and an optimal driver's seat by using review of the literature of seated positions of the head. spine, pelvis, and lower extremities. DATA SELECTION: Searches included MEDLINE for scientific journals, engineering standards, and textbooks. Key terms included sitting ergonomics, sitting posture, spine model, seat design, sitting lordosis, sitting electromyography, seated vibration, and sitting and biomechanics. DATA SYNTHESIS: In part I, papers were selected if (1) they contained a first occurrence of a sitting topic, (2) were reviews of the literature, (3) corrected errors in previous studies, or (4) had improved study designs compared with previous papers. In part II, we separated information pertaining to sitting dynamics and drivers of automobiles from part 1. RESULTS: Sitting causes the pelvis to rotate backward and causes reduction in lumbar lordosis, trunk-thigh angle, and knee angle and an increase in muscle effort and disc pressure. Seated posture is affected by seat-back angle, seat-bottom angle and foam density, height above floor, and presence of armrests. CONCLUSION: The configuration of the spine, postural position, and weight transfer is different in the 3 types of sitting: anterior, middle, and posterior. Lumbar lordosis is affected by the trunk-thigh angle and the knee angle. Subjects in seats with backrest inclinations of 110 to 130 degrees, with concomitant lumbar support, have the lowest disc pressures and lowest electromyography recordings from spinal muscles. A seat-bottom posterior inclination of 5 degrees and armrests can further reduce lumbar disc pressures and electromyography readings while seated. To reduce forward translated head postures, a seat-back inclination of 110 degrees is preferable over higher inclinations. Work objects, such as video monitors, are optimum at eye level. Forward-tilting, seat-bottom inclines can increase lordosis, but subjects give high comfort ratings to adjustable chairs, which allow changes in position.

Biomechanical Phenomena↗
PubMedDate not supplied

A review of biomechanics of the central nervous system--Part III: spinal cord stresses from postural loads and their neurologic effects.

OBJECTIVE: To review literature pertaining to neurologic disorders stemming from abnormal postures of the spine. DATA COLLECTION: A hand search of available reference texts and a computer search of literature from Index Medicus sources was performed, with special emphasis placed on spinal cord stresses and strains caused by various postural rotations and translations of the skull, thorax, and pelvis. RESULTS: Spinal postures will often deform the neural elements within the spinal canal. Spinal postures can be broken down into four types of loading: axial, pure bending, torsion, and transverse, which cause normal and shear stresses and strains in the neural tissues and blood vessels. Prolonged stresses and strains in the neural elements cause a multitude of disease processes. CONCLUSION: Four types of postural loads create a variety of stresses and strains in the neural tissue, depending on the exact magnitude and direction of the forces. Transverse loading is the most complex load. The stresses and strains in the neural elements and vascular supply are directly related to the function of the sensory, motor, and autonomic nervous systems. The literature indicates that prolonged loading of the neural tissue may lead to a wide variety of degenerative disorders or symptoms. The most offensive postural loading of the central nervous system and related structures occurs in any procedure or position requiring spinal flexion. Thus flexion traction, rehabilitation positions, exercises, spinal manipulation, and surgical fusions in any position other than lordosis for the cervical and lumbar spines should be questioned.

Biomechanical Phenomena↗