Search PubMed⌕ Search

Biomedical subjects

C G Davis

Publications and source records attributed to C G Davis.

45 records · Page 3Linked to original sources
PubMed1979

Folacin and iron status and hematological findings in predominately black elderly persons from urban low-income households.

The folacin and iron status and hemotological parameters of 193 persons 60 years of age and older from urban low-income households were evaluated. Of the serum folacin values 30% were between 3 and 6 ng/ml and 8% were below 3 ng/ml. Of these subjects 60% could be classified as "high risk" (less than 140 ng/ml) and 11% as "medium risk" (140 to 160 ng/ml) based on red blood cell folacin concentrations. Serum iron was normal (greater than 50 micrograms/dl) for all subjects as was transferrin saturation (greater than 15%). Hematological indices showed a 14% incidence of anemia (hemaglobin less than 12 g/dl), and 32% incidence of leukopenia (leukocytes less than 4.8 X 10(3)). These findings demonstrate widespread folacin deficiency and no evidence of iron deficiency in these elderly people.

Aged↗
PubMed1977

Phosphorylation of membrane proteins at a cholinergic synapse.

Endogenous membrane protein kinase activity and protein kinase substrates have been found in membrane fractions enriched in the acetylcholine receptor that were prepared from the electric organ of Torpedo californica. Phosphorylation of four polypeptides is stimulated 9-fold by K+. The specific cholinergic ligand, carbachol, inhibited phosphorylation of these four polypeptides by 72% in the presence of 1mM Na+ and 100 mM K+. The 65,000-dalton component of the acetylcholine receptor in the membrane fraction appears to be phosphorylated by the endogenous protein kinase. These results suggest that protein phosphorylation may play an important role in synaptic events at nicotinic cholinergic synapses.

Animals↗
PubMedDate not supplied

Injury threshold: whiplash-associated disorders.

OBJECTIVES: To review current knowledge and recent concepts of the causes of injuries after minor impact automobile collisions and to acquaint those who treat these types of injuries with possible injury thresholds and mechanisms that may contribute to symptoms. DATA SOURCES: A review of literature involving mechanisms of injury, tissue tensile threshold, and neurologic considerations was undertaken. A hand-search of relevant engineering, medical/chiropractic, and computer Index Medicus sources in disciplines that cover the variety of symptoms was gathered. RESULTS: Soft-tissue injuries are difficult to diagnose or quantify. There is not one specific injury mechanism or threshold of injury. With physical variations of tissue tensile strength, anatomic differences, and neurophysiologic considerations, such threshold designation is not possible. CONCLUSIONS: To make a competent assessment of injury, it is important to evaluate each patient individually. The same collision may cause injury to some individuals and leave others unaffected. With the variability of human postures, tensile strength of the ligaments between individuals, body positions in the vehicle, collagen fibers in the same specimen segment, the amount of muscle activation and inhibition of muscles, the size of the spinal canals, and the excitability of the nervous system, one specific threshold is not possible. How individuals react to a stimulus varies widely, and it is evident peripheral stimulation has effects on the central nervous system. It is also clear that the somatosensory system of the neck, in addition to signaling nociception, may influence the control of neck, eyes, limbs, respiratory muscles, and some preganglionic sympathetic nerves.

Accidents, Traffic↗
PubMedDate not supplied

Irradiation of singly and doubly transduced murine neuroblastoma cells expressing B7-1 and producing interferon-gamma reduces their capacity to induce systemic immunity.

We have previously reported that immunization with low major histocompatibility complex (MHC) class I expressing murine neuroblastoma (neuro-2a) transduced with B7-1 fails to induce significant protection to wild-type tumor challenge. In this study we investigated whether B7-1 expressing neuro-2a cells can stimulate an effective T-cell response if they were cotransduced with the interferon-gamma (IFN-gamma) gene to upregulate MHC class I. Transfer of both the IFN-gamma and B7-1 genes into neuro-2a (N-2a/B7-1/IFN) almost completely abrogated the tumorigenic potential of this tumor and improved survival when compared with mice receiving the single transductants, N-2a/IFN and N-2a/B7-1. Rejection of N-2a/B7-1/IFN was mediated primarily by CD8+ T cells. When irradiated tumor cells were tested, IFN-gamma gene transfer into neuro-2a significantly increased immunogenicity, but transfer of the B7-1 gene did not. However, nonirradiated N-2a/B7-1, N-2a/IFN, and N-2a/B7-1/IFN cells were significantly more effective in eliciting systemic immunity against subsequent wild-type tumor challenge than their irradiated counterparts. N-2a/B7-1/IFN was more immunogenic than N-2a/B7-1 but not more than N-2a/IFN, indicating that B7-1 does not further increase immunogenicity of neuro-2a over that induced by IFN-gamma transduction. These findings should be considered when designing gene modified tumor vaccines for use in human trials.

Animals↗
PubMedDate not supplied

Rear-end impacts: vehicle and occupant response.

BACKGROUND: There is a controversy regarding the likelihood of injuries sustained when one car strikes another at a relatively low speed with little or no vehicle damage. Plaintiffs often claim injuries whereas defendants counterclaim that injuries could not have occurred with such a relatively minor impact. OBJECTIVE: To review the dynamics of low-speed rear-end collisions resulting in little or no visible damage and to decide whether occupant injury can occur; also, to discuss diagnostic examination and treatment that may be helpful to the clinical practitioner. DATA SELECTION: A Medline search for articles discussing low-speed rear-end collisions was conducted. Other articles and studies were reviewed that discussed low-speed rear-end collisions and factors impacting the neuromusculoskeletal system relevant to clinical practitioners. Articles included were human low-speed rear-end tests, lab tests on cadavers, automotive engineering articles, and peer-reviewed journal articles on whiplash. A few live animal and simulation studies were considered for the background of possible injury mechanism and vehicular deformation. Excluded were non-rear-end collison and single case reports. DATA SYNTHESIS: The data were studied to find a relationship between the resultant vehicle dynamics and occupant movement, biological mechanisms of injury and the neurological mechanisms causing complaints. Data were also studied to investigate objective findings supporting subjective complaints. CONCLUSION: In low-impact collisions, there are usually no skid marks and minor or no visible damage to the vehicle. There is a lack of relationship between occupant injury, vehicle speed and/or damage. There does not seem to be an absolute speed or amount of damage a vehicle sustains for a person to experience injury. Crash tests indicate that a change of vehicle velocity of 4 km/hr (2.5 mph) may produce occupant symptoms. Vehicle damage may not occur until 14-15 km/hr (8.7 mph). Occupant soft tissue and joint injuries resulting from low-speed vehicle collisions respond positively to afferent stimulation of mechanoreceptors. The diagnosis of the occupant injuries relies on standard orthopedic neurological testing, autonomic concomitant signs and qualitative and quantitative testing.

Accidents, Traffic↗