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Biomedical subjects

K L Koenig

Publications and source records attributed to K L Koenig.

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

The low carcinogenicity of electron radiation relative to argon ions in rat skin.

The carcinogenicity of electron radiation relative to argon ions in rat skin was examined, specifically investigating whether the linear-quadratic model is useful for predicting cancer yield for one type of radiation based on yields observed for a different type. Three experiments were conducted to obtain information on the relationship between cancer yield and the dose of electron radiation: (1) a conventional dose-response protocol where the number of rats per group was based on the expected tumor yield; (2) a multiple-fraction protocol designed to take advantage of yield additivity as a way to estimate carcinogenicity at lower doses; and (3) a protocol to examine the effect of age at the time of irradiation on the dose-response relationship for cancer induction. Published data on the induction of skin cancer in rats irradiated with electrons were reanalyzed and combined with results of the new experiments. Skin cancer yield versus dose for argon ions was consistent with the linear-quadratic model, but the cancer yield for electrons was considerably lower (by a factor of 6.7 at 10 Gy) than the prediction based on the linear-quadratic model. The cancer yield for electron radiation was better fitted by a dose-cubed power function than a linear-quadratic function. The results indicate a substantially lower carcinogenic effectiveness for electron radiation, especially at lower doses, in comparison to argon ions and suggest that electrons may cause cancer by a three-event pathway instead of the two-event pathway that is consistent with the results for argon ions.

Animals↗
PubMed1992

Reproducibility of Wolfe's classification of mammographic parenchymal patterns.

BACKGROUND: Inadequate reproducibility of Wolfe's classification of mammographic parenchymal patterns may explain its limited use in clinical and screening practice. If the misclassification of mammographic parenchymal pattern categories is substantial, inconsistencies in study results will occur, which could at least partially explain the frequent inability to replicate Wolfe's findings in studies of breast cancer. In this article, results of a study to determine whether consensus to resolve inconsistencies between raters would improve the level of concordance in mammographic parenchymal pattern categorization and thus help reduce misclassification are presented. METHODS. One hundred consecutive mammograms from a large screening clinic in New York City were classified independently by two expert mammographers on two separate occasions, 8 days apart. Coding was repeated in two consensus conferences several weeks later. Reliability was estimated by computing intraclass correlation coefficients. RESULTS: Initially, the average intraobserver reliability for the four patterns was 0.68 and the interobserver reliability was 0.65. After consensus, reliability improved markedly to 0.88. CONCLUSION: It is concluded that the added complication and cost of consensus ratings will be more than offset by a substantial increase in precision.

Adult↗
PubMed1992

Age-dependence of responses to acute ozone exposure in rats.

Previous work from this laboratory demonstrated that neonatal rats and postweanling rabbits are more sensitive to ozone-induced stimulation of pulmonary arachidonic acid (AA) metabolism than are young adults (Fundam. Appl. Toxicol. 15, 779.) In the study reported here, we have extended our initial investigation to include the influence of animal age on temporal aspects of pulmonary AA metabolism and several other responses to brief exposures to 1 ppm ozone. Rats of discrete ages ranging from 13 days to 16 weeks were exposed to 1 ppm ozone or to air for 2, 4, or 6 hr. Immediately following exposure the lungs were lavaged with six consecutive volumes of phosphate-buffered saline and the acellular fluid from the first lavage volume recovered was analyzed for its content of prostaglandin E2 (PGE2), protein, and lactate dehydrogenase. Leukocytes recovered by lavage were quantitated and characterized by viability and percentage of polymorphonuclear (PMN) cells. Several lines of evidence verified that PGE2 was produced by the lung as a consequence of ozone exposure and that its concentration in the fluid from the first lavage was a reasonably good index of pulmonary AA metabolism to prostanoids. We also demonstrated that the lavage process itself stimulates the lung, resulting in increased AA metabolism to prostanoids that were recovered in the second and following lavage volumes. The time course of PGE2 production by the ozone-exposed lung varied considerably with animal age. Neonatal rats 13 days of age were the most sensitive to ozone stimulation. At 2 hr of exposure, PGE2 concentration in the first lung lavage of these animals peaked at values approximately two orders of magnitude above controls and then decreased sharply with continued exposure. Adults and older neonates (18 days of age) were much less responsive to 2-hr exposures; however, continued exposure of these rats for up to 6 hr resulted in increasing PGE2 concentration in the first lung lavage. Other responses showed various degree of age dependence. The percentage of lavaged leukocytes that were nonviable (i.e., trypan blue-positive) showed a strong inverse correlation with animal age. In 13-day-old rats that were exposed for 6 hr, the percentage of dead leukocytes reached nearly 50%. In addition, sheets or clumps of dead cells that were judged to be epithelial cells were lavaged from these animals. Conversely, 16-week-old adult males exposed to ozone for 6 hr showed little evidence of damage to cells of the respiratory tract.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1992

Rapid-sequence intubation of head trauma patients: prevention of fasciculations with pancuronium versus minidose succinylcholine.

INTRODUCTION: Fasciculations during rapid-sequence intubation may lead to increased intracranial pressure and emesis with aspiration. Standard rapid-sequence intubation requires a nondepolarizing blocking agent before succinylcholine administration. HYPOTHESIS: Prevention of fasciculations during rapid-sequence intubation of head trauma patients can be accomplished as safely and effectively with minidose succinylcholine as with a defasciculating dose of pancuronium. DESIGN: A prospective, randomized, double-blind study. SETTING: An inner-city county trauma center with 70,000 patient visits per year. PARTICIPANTS: Sequential adult head trauma patients requiring rapid-sequence intubation who had no contraindications to succinylcholine or pancuronium. INTERVENTIONS: Each head trauma patient requiring rapid-sequence intubation who met the inclusion criteria received standard rapid-sequence intubation maneuvers and lidocaine (1 mg/kg) IV. Patients were randomized to receive either minidose succinylcholine (0.1 mg/kg) or pancuronium (0.03 mg/kg) IV one minute prior to the full paralytic dose of succinylcholine (1.5 mg/kg) IV. Fasciculations were recorded using a graded visual scale. RESULTS: Of 46 patients, eight of 19 (42%) in the pancuronium group and six of 27 (22%) in the succinylcholine group experienced fasciculations. No statistically significant difference in fasciculations was detected between the two groups using chi 2 analysis. Complete relaxation of the cords was present in all but two patients, one in each group. No patient in either group experienced emesis or significant dysrhythmias. CONCLUSION: Pretreatment with minidose succinylcholine causes no greater incidence of fasciculations than pancuronium in rapid-sequence intubation of head trauma patients in an ED setting. Thus succinylcholine may be used as the sole paralytic agent in rapid-sequence intubation of head trauma patients.

Adult↗
PubMed1991

Hair dye use and breast cancer: a case-control study among screening participants.

To investigate whether hair dye use increases the risk of breast cancer, a case-control study was conducted among patients attending a screening center in New York City. The study group consisted of 398 breast cancer cases identified at the screening center between 1977 and 1981, and 790 randomly selected controls screened during the same period. Subjects were interviewed by telephone to obtain information on known risk factors for breast cancer, along with a complete history of hair dye use detailing type of dye, color, duration, frequency, and temporal periods of use. Most subjects (77%) had used hair dye at least once, 38% of the subjects at least 100 times. However, little increased risk of breast cancer was found among hair dye users. The adjusted odds ratio for ever having used hair dye was 0.8 (95% confidence interval 0.6-1.1), and there was no evidence of a trend in risk with increasing number of hair dye uses. The results were the same whether all past exposures were considered or only exposures more than 10 years before disease. Breast cancer risk did not increase with increasing intensity of exposure, as measured by frequency of use or darkness of color. No effect was seen for different types or colors of dye, or for use during different periods of reproductive life. Although personal hair dye use was unrelated to breast cancer risk, there was an adjusted odds ratio of 3.0 (95% confidence interval 1.1-7.8) for 5 or more years of work as a beautician. Overall, the results of this study, taken in conjunction with the findings of other epidemiologic studies, do not implicate hair dye use as an important cause of human breast cancer.

Adult↗
PubMed1991

Endogenous hormones and breast cancer: a prospective cohort study.

A cohort study is under way in New York City to evaluate how levels of endogenous reproductive hormones influence the risk of breast cancer. The study, in which approximately 15,000 women are being recruited, utilizes a prospective design in which volunteers are asked to provide repeated specimens of serum during the period 1985-1992. A case-control study nested within the cohort is planned by which specimens from all cases arising in the population and from a randomly selected sample of time-matched controls will be analyzed and compared. As of December 31, 1989, 13,609 volunteers had donated blood specimens, about 50% of whom had already donated more than once. Of the 187 incident breast cancer cases who are expected to arise in the cohort before the end of 1992, 77 have been detected thus far.

Adult↗
PubMed1991

Vibrio vulnificus. Hazard on the half shell.

Vibrio vulnificus is an extremely invasive gram-negative bacillus that causes bacteremia and shock. It should be suspected in any patient who is immunocompromised or has liver disease or hemochromatosis. Reduced gastric acidity may also increase the risk of infection if a patient presents with a history of ingesting raw shellfish (especially oysters) or trauma in brackish waters and skin lesions. Patients most commonly present with one of three clinical syndromes: primary septicemia, wound infection, or gastroenteritis. Treatment includes aggressive wound debridement, antibiotic therapy, and supportive care. Rapidly diagnosing and promptly initiating therapy are critical because V vulnificus infection is rapidly progressive and mortality approaches 100% if septic shock occurs.

Animals↗
PubMed1990

Carcinogenic sulfide salts of nickel and cadmium induce H2O2 formation by human polymorphonuclear leukocytes.

Some derivatives of nickel, cadmium, and cobalt are carcinogenic in humans and/or animals but their mechanisms of action are not known. We show that they are capable of stimulating human polymorphonuclear leukocytes (PMNs), as measured by H2O2 formation, a known tumor promoter. Most effective were the carcinogens nickel subsulfide, which caused a 550% net increase in H2O2 over that formed by resting PMNs, followed by cadmium sulfide, 400%, and nickel disulfide, 200%. Nickel sulfide and cobalt sulfide caused statistically nonsignificant increases of 45 and 20%, respectively. Noncarcinogenic barium and manganese sulfides, and sulfates of nickel, cadmium, and cobalt were inactive. The enhancement of H2O2 formation by CdS and Ni3S2 (1 mumol/2.5 x 10(5) PMNs) was comparable to that mediated by the potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate, used at 0.5 and 1 nM, respectively. Concurrent treatment of 12-O-tetradecanoylphorbol-13-acetate-stimulated PMNs with Ni3S2 or NiS caused a decrease in H2O2 accumulation from that expected if the effects were additive. Including catalase in the reaction mixture proved that the oxidant formed by stimulated PMNs was H2O2, whereas adding superoxide dismutase showed that superoxide was also present in PMN samples treated with NiS but not with Ni3S2. Since nickel- and cadmium-containing particulates are deposited in the lungs and cause infiltration of PMNs, the ability to activate those cells and induce H2O2 formation may contribute to their carcinogenicity.

Barium↗
PubMedDate not supplied

Code blue: what's new?

In October 1992, lengthy new guidelines for cardiopulmonary resuscitation and emergency cardiac care were published by the Emergency Cardiac Care Committee and Subcommittees of the American Heart Association. These guidelines represent the efforts of the world's experts in emergency cardiac care. Yet they may be difficult for the busy clinician to digest in a timely fashion. In this article we summarize the changes in the guidelines from the 1986 version. It is not intended as a substitute for the original document but rather as an adjunct to help the clinician assimilate this new information.

Adult↗
PubMedDate not supplied

Do-not-resuscitate orders. Where are they in the prehospital setting?

Without a well-functioning, prehospital, do-not-resuscitate (DNR) system in place, emergency medical service (EMS) providers must resuscitate all patients who access the system, regardless of the patients' wishes and regardless of what makes ethical or economic sense. In lieu of valid documentation, it is not appropriate to withhold resuscitative measures in this critical, time-dependent situation. In order to help EMS systems implement functional prehospital DNR protocols, this paper reviews the state-of-the-art of prehospital DNR including the issues to consider when designing such a system and a discussion of the features of some of the existing systems. This review includes: 1) the basis and requirements of a DNR system; 2) legal and physical forms for DNR orders; 3) eligibility for DNR status; 4) reversal of DNR orders; and 5) inappropriate use of EMS systems for DNR patients. Finally, a more general discussion of overall resource utilization in prehospital resuscitations is presented to emphasize that implementing prehospital DNR systems is only one piece of a larger issue.

Advance Directives↗
PubMedDate not supplied

Disaster triage: START, then SAVE--a new method of dynamic triage for victims of a catastrophic earthquake.

Triage of mass casualties in situations in which patients must remain on-scene for prolonged periods of time, such as after a catastrophic earthquake, differs from traditional triage. Often there are multiple scenes (sectors), and the infrastructure is damaged. Available medical resources are limited, and the time to definitive care is uncertain. Early evacuation is not possible, and local initial responders cannot expect significant outside assistance for at least 49-72 hours. Current triage systems are based either on a shorter time to definitive care or on a longer time to initial triage. The Medical Disaster Response (MDR) project deals with the scenario in which specially trained, local health-care providers evaluate patients immediately after the event, but cannot evacuate patients to definitive care. For this type of scenario, a dynamic triage methodology was developed that permits the triage process to evolve over hours or even days, thereby maximizing patient survival and resulting in a more efficient use of resources. This MDR system incorporates a modified version of "Simple Triage and Rapid Treatment" (START) that substitutes radial pulse for capillary refill, coupled with a system of secondary triage termed, "Secondary Assessment of Victim Endpoint" (SAVE). The SAVE triage was developed to direct limited resources to the subgroup of patients expected to benefit most from their use. The SAVE assesses survivability of patients with various injuries and, on the basis of trauma statistics, uses this information to describe the relationship between expected benefits and resources consumed. Because early transport to an intact medical system is unavailable, this information guides treatment priorities in the field to a level beyond the scope of the START methodology. Pre-existing disease and age are factored into the triage decisions. An elderly patient with burns to 70% of body surface area is unsalvageable under austere field conditions and would require the use of significant medical resources-both personnel and equipment-and would be triaged to an "expectant area." Conversely, a young adult with a Glasgow Coma Scale score of 12 who requires only airway maintenance would use few resources and would have a reasonable chance for survival with the interventions available in the field, and would be triaged to a "treatment" area. The START and SAVE triage techniques are used in situations in which triage is dynamic, occurs over many hours to days, and only limited, austere, field, advanced life support equipment is readily available. The MDR-SAVE methodology is the first systematic attempt to use triage as a tool to maximize patient benefit in the immediate aftermath of a catastrophic disaster.

Abdominal Injuries↗