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Biomedical subjects

D H Davis

Publications and source records attributed to D H Davis.

At least 73 records · Page 4Linked to original sources
PubMed1980

Relationship of cerebral blood flow to cardiac output, mean arterial pressure, blood volume, and alpha and beta blockade in cats.

The relationship among cerebral blood flow (CBF), blood volume, cardiac output (CO), and mean arterial blood pressure (MABP) at varying levels of arterial CO2 tensions (PaCO2) were studied in 70 normal cats. The CBF was measured from the clearance curve of xenon-133 and CO with a thermal dilution catheter placed in the pulmonary artery. The CBF, CO, and MABP values varied appropriately with changes in PaCO2, confirming the reliability of the preparations and the presence of normal autoregulatory responses. Moderate hypovolemia that did not change MABP did, nevertheless, significantly decrease CO and CBF. In an effort to determine if this decrease in CO and CBF were coupled responses, the effects of beta stimulation, hypervolemia, and alpha and beta blockade were investigated. Propranolol, in a dosage insufficient to change MABP, decreased both CO and CBF. This agent abolished the CO response to elevations in PaCO2 but not the CBF response, making it unlikely that this CBF reduction resulted from impaired cerebral autoregulation. Isoproterenol, which, in contrast to propranolol, does not cross the normal blood-brain barrier, alone or in combination with phenoxybenzamine, produced a 38% and 72% increase in CO, respectively, without a change in CBF. Alpha blockade (no major change in CO) and beta blockage (major decrease in CO) did not significantly effect cerebral autoregulation to changes in MABP from angiotensin. The ability of the brain to resist increases in MABP and CO and maintain normal CBF is explained by normal cerebral autoregulation. However, its vulnerability to modest decreases in blood volume, which cannot be attributed to variations in perfusion pressure, is unexplained but obviously has important therapeutic implications. This may be related to reduction in CO, changes in autonomic activity, or a decrease in the size of the perfused capillary bed.

Adrenergic alpha-Antagonists↗
PubMed1980

Safety and OSHA.

Explore the source record for details and available documents.

Accident Prevention↗
PubMed1978

Brachial plexus injuries.

Brachial plexus injuries are uncommon. They are, however, complicated lesions because of the concomitant injury to adjacent structures and the imposing anatomy of the brachial plexus. Physicians who will be consulted in the management of such injuries should periodically consider the principles of management. Diagnosis of these injuries is based on clinical examination, myelography, axon reflex testing, and electrophysiologic studies. The lesion may be open or closed and supraclavicular or infraclavicular. It may be in continuity or there may be nerve disruption or root avulsion from the spinal cord. The anatomic relationships of the brachial plexus are reviewed, the pathophysiology of direct trauma, secondary trauma, and iatrogenic trauma is discussed, and the treatment of the various types of traumatic brachial palsy is surveyed.

Brachial Plexus↗
PubMed1976

Serological studies on human plague in Southern Africa. Part II. A bubonic/pneumonic plague epidemic in Lesotho.

A description is given of an outbreak of human plague in Lesotho in 1968 which was preceded by, and merged with, a typhoid epidemic. This circumstance was responsible for a diagnosis of typhoid fever being made in the earliest plague cases, especially as the clinical presentation was similar to that of the typhoid patients. Consequently, the plague epidemic ran its natural course and with the onset of winter the pneumonic form appeared. Serological follow-up studies of recovered patients were carried out up to 4 years after the outbreak.

Adolescent↗
PubMed1976

Antecedents of narcotic use and addiction. A study of 898 Vietnam veterans.

Previous studies of predictors of narcotic abuse have been retrospective and based on samples of long-term addicts obtained from legal or medical channels. There are several methodological problems in this approach. The present study is an attempt to test certain alleged predictors of narcotic use in a cohort of 898 Vietnam veterans. The design overcomes several of the methodological weaknesses of previous studies. Eight variables which have been reported as predictors of drug use or addiction in the drug literature were inquired about during a personal interview which included the premilitary life of each subject. The antecedent variables were socioeconomic background, inner city residence, psychiatric illness, broken home, race, employment history, education and antisocial history. Using information obtained from interviews and military records, we then tested the predictive value of each of these antecedents by comparing narcotic used and addiction in Vietman and use after Vietnam in men differing with respect to each antecedent. Results indicate that some of the variables were very poor, and others very good predictors of the various levels of narcotic involvement. The predictive value and overall importance of each of the variables we tested are discussed.

Adult↗
PubMed1976

Depressive disorders in Vietnam returnees.

A random sample of 470 Army enlisted men who served tours of duty in Vietnam and returned to the United States in September, 1971 was selected from military records. Between May and September, 1972, these servicemen were located and personally interviewed. Additional information was obtained from their military records and from Veterans Administration files. Interviews were obtained for 95% and military records for 99%. Veterans Administration records were available for 22% of the sample. Depressive disorders appeared to be a significant problem in these enlistees after their return. Twenty-six per cent of the total sample reported at least some symptoms of depression, and 7 per cent reported a full affective syndrome. A third of those with depressive syndromes have had psychiatric care since their return. The association of depression with combat, use of illicit drugs, and other pre- and post-Vietnam variables is discussed.

Adult↗
PubMed1975

Drinking amid abundant illicit drugs. The Vietnam case.

We studied drinking patterns and problems of 451 US Army enlisted men after their return from Vietnam. Before Vietnam, nearly half were regular drinkers and one quarter had drinking problems. Problem drinking declined in Vietnam as opiate use rose sharply; half had tried opiates and 20% were opiate dependent. After Vietnam, opiate use decreased (now less than 2% opiate dependent) and problem drinking again became ascendant. At time of interview, 17% had drunk in an alcoholic pattern at some period in their lives and another 41% had had problems from drinking. The younger men were more likely to have had problems. Alcholism predictors included:becoming intoxicated at an early age; dropping out of school; truancy and expulsion from school; and having a father with a history of alcoholism or arrests.

Adolescent↗
PubMed1975

Narcotic use in southeast Asia and afterward. An interview study of 898 Vietnam returnees.

From all US Army enlistees leaving Vietnam in September 1971, a random sample of 943 men was selected. Of these, 470 represented a "general" sample of all enlistees returning at that time, and 495 represented a "drug positive" sample whose urine samples had been positive for opiates at the time of departure. We attempted to locate and personally interview all of the men in the samples. Results indicate that before arrival, hard drug use was largely casual, and less than 1% had ever been addicted to narcotics. In Vietnam, almost half of the general sample tried narcotics and 20% reported opiate addiction. After return, usage and addiction essentially decreased to pre-Vietnam levels. We discuss the use of nonnarcotic drugs, predictors and correlates of drug use in the samples, and the relationship of drugs to post-Vietnam social adjustment.

Age Factors↗
PubMed1966

The susceptibility of rodents to schistosome infection, with special reference to Schistosoma haematobium.

In this investigation the susceptibility of several species of rodents-Praomys (Mastomys) natalensis, Saccostomus campestris, Arvicanthus niloticus, Aethomys chrysophilus, Tatera brantsi and the white mouse (SAIMR 200 strain)-to Schistosoma haematobium was determined and the pathology studied. From the results it is clear that these rodents are susceptible to infection with Schistosoma haematobium. For various reasons, notably adaptability to laboratory conditions, the most suitable as laboratory animals for the study of bilharziasis are Saccostomus campestris, Arvicanthus niloticus and Praomys (Mastomys) natalensis. These three species breed readily in the laboratory and show a high susceptibility to S. haematobium, with characteristic lesions involving several organs, including the lungs, liver, spleen, pancreas and intestine.

Animals↗