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Biomedical subjects

P Martin

Publications and source records attributed to P Martin.

At least 253 records · Page 14Linked to original sources
PubMed2000

Rib fracture patterns and radiologic detection--a restraint-based comparison.

This paper presents a study of the rib fracture patterns generated in simulated frontal collisions and the visibility of the rib fractures on plain film radiographs. Using 29 cadaver subjects, rib fractures were identified on oblique, lateral, and anteroposterior chest films by five radiologists independently and were compared with fractures found during a detailed necropsy. Physical, geometric, and experimental factors demonstrated an influence on the ability of a radiologist to identify rib fractures on an x-ray. Specifically, the restraint system configuration, the total number of fractures, the circumferential location of the fracture, the rib number, and the aspect (right or left) affected fracture identification. The results verify that torso belt loading produces rib fractures generally located along the path of the belt whereas superimposed airbag loading results in a more distributed and posterolateral fracture pattern. A higher proportion of rib fractures was identified on x-ray for occupants restrained by only a belt (44% of fractures) than for occupants restrained by both a belt and an airbag (24% of fractures). Overall, less than 40% of the rib fractures were detected upon an initial examination of radiographs. After being provided with the location of all fractures, detection increased to 49%. On average, occult rib fractures resulted in an average underreporting of injury severity of more than one AIS level.

Acceleration↗
PubMed2000

Injuries to restrained occupants in far-side crashes.

Occupants exposed to far-side crashes are those seated on the side of the vehicle opposite the struck side. This study uses the NASS/CDS 1988-98 to determine distributions of AIS 3+ injuries among occupants exposed to far-side crashes and the sources of the injuries. The William Lehman Injury Research Center (WLIRC) data from 1994-98 is used to assess injury mechanisms among seriously injured crash exposed far-side occupants. The NASS/CDS indicated that injury patterns for far-side restrained drivers were different from far-side restrained front passengers. For the driver, the head accounted for 40% of the AIS 3+ injuries in far-side collisions and the chest/abdomen accounted for 45.5%. For the right front passengers, head injuries contributed 27.2%, while chest and abdominal injuries accounted for 64.5%. The opposite-side interior was the most frequent contact associated with driver AIS 3+ injuries (30.5%). The seat belt was second, accounting for 22.6%. Among thirteen WLIRC cases of far-side belted occupants with MAIS 3+ injuries, five of the most serious injuries were attributed to the seat belt. The liver or the spleen was the most seriously injured body organ in all five cases. The seat was the most frequent source of passenger AIS 3+ injuries for the NASS/CDS weighted cases. However, non-contacts, contacts with other occupants, and the seat belt contacts were more frequent sources when considering the raw number of injuries. Overall, contacts with the opposite side of the car interior and with safety belts were the most frequent causes of AIS 3+ injuries in far-side crashes. The presence of an occupant on the near-side changed the injury pattern of the far-side occupant, mitigating injuries from contacts with the opposite side interior of the vehicle.

Accidents, Traffic↗
PubMed1999

Active hair-bundle movements can amplify a hair cell's response to oscillatory mechanical stimuli.

To enhance their mechanical sensitivity and frequency selectivity, hair cells amplify the mechanical stimuli to which they respond. Although cell-body contractions of outer hair cells are thought to mediate the active process in the mammalian cochlea, vertebrates without outer hair cells display highly sensitive, sharply tuned hearing and spontaneous otoacoustic emissions. In these animals the amplifier must reside elsewhere. We report physiological evidence that amplification can stem from active movement of the hair bundle, the hair cell's mechanosensitive organelle. We performed experiments on hair cells from the sacculus of the bullfrog. Using a two-compartment recording chamber that permits exposure of the hair cell's apical and basolateral surfaces to different solutions, we examined active hair-bundle motion in circumstances similar to those in vivo. When the apical surface was bathed in artificial endolymph, many hair bundles exhibited spontaneous oscillations of amplitudes as great as 50 nm and frequencies in the range 5 to 40 Hz. We stimulated hair bundles with a flexible glass probe and recorded their mechanical responses with a photometric system. When the stimulus frequency lay within a band enclosing a hair cell's frequency of spontaneous oscillation, mechanical stimuli as small as +/-5 nm entrained the hair-bundle oscillations. For small stimuli, the bundle movement was larger than the stimulus. Because the energy dissipated by viscous drag exceeded the work provided by the stimulus probe, the hair bundles powered their motion and therefore amplified it.

Animals↗
PubMed1999

Intraclonal polymorphism in the bacterium Streptomyces ambofaciens ATCC23877: evidence for a high degree of heterogeneity of the wild type clones.

In Streptomyces ambofaciens a genetic instability generates a high degree of polymorphism consisting of four main phenotypes: pigmented colonies (Pig(+) qualified as WT phenotype), pigment-defective colonies, pigmented colonies with pigment-defective sector and pigmented colonies with pigment-defective papillae. Molecular analysis of Pig(col)(-) and Pig(sec)(-) (pigment-defective mutant derived from a colony and a sector, respectively) produced by genetic instability and isolated in five Pig(+) subclones progenies revealed a new aspect of polymorphism in S. ambofaciens ATCC23877. Frequencies of Pig(col)(-) and Pig(sec)(-) mutants deleted at the chromosome ends varied from one WT progeny to another. Two main types of deleted mutants were observed: deleted for one or both chromosomal extremities. The relative proportion of these two categories differed according to the WT progeny. These results argue for heterogeneity of the WT clones, i.e., Pig(+) colonies, originated from S. ambofaciens ATCC23877.

Chromosomes, Bacterial↗
PubMed1999

[Knowledge about Helicobacter pylori and antibiotic treatment of peptic ulcer. A model study of information dissemination and implementation of the new knowledge in clinical practice].

Dissemination of information concerning new knowledge on peptic ulcer disease caused by Helicobacter pylori and treatment with antibiotics was surveyed. In 1996 a questionnaire was mailed to 200 gastroenterologists and 200 general practitioners. Physicians enumerate national medical journals as the most frequent source of information about the relationship between Helicobacter pylori and gastrointestinal ulcer. Six years after the first publication in international journals, 44% of the doctors had noticed this relation. Nearly all physicians had introduced antibiotics in treatment af peptic ulcer disease ten to twelve years after first announcement. The gastroenterologists preferred international medical journals whereas general practitioners stated national medical journals were the most important sources of new knowledge. General practitioners lacked knowledge of published guidelines for treatment of peptic ulcer disease.

Clinical Competence↗
PubMed1999

Tuberculosis in immigrants and visitors.

Immigrants and visitors are a significant factor in the epidemiology of tuberculosis (TB) in New Zealand, accounting for an increasing proportion of notifications in recent years. At present screening of immigrants from countries with a high incidence of TB is inadequate. There are deficiencies in procedures, inadequate screening coverage, ineffectual coordination between the Ministry of Health and New Zealand Immigration Service, incomplete follow-up on those at risk of TB, confusion over financial responsibility, inadequate data to describe the problems and monitor interventions, and a lack of commitment to assistance with TB control in neighbouring countries from which some of our TB arises. We make recommendations in all of these areas. Timely screening of high-risk immigrants should be seen as health protection for ethnic minorities.

Emigration and Immigration↗
PubMed1999

[Medico-socio-economic aspects of mental health: impact of anxiety disorders].

Budgetary control policies implemented in order to cope with the increase in health costs in industrialised countries, all along with the inbalance of the national health insurance accounts, give rise to the problem of preserving the quality of care and quality of life of the patients. This is particularly true for the treatment of psychiatric diseases, and especially anxiety. Early optimal treatment, of adequate duration, of the anxiety disorders might be the most economic attitude in the management of this pathology. On the other hand, the impact of the treatment of anxiety on the quality of life of the patient has a direct effect on costs if one considers the supplement to medical consumption and the social deficit induced by therapeutic failure in particular anxiety disorders. It remains that the evaluation of the health economics of anxiety is difficult, because of the complexity of the parameters involved.

Anxiety Disorders↗
PubMed1999

Imaging of asteroid 433 eros during NEAR's flyby reconnaissance

During the 23 December 1998 flyby of asteroid 433 Eros, the Near-Earth Asteroid Rendezvous (NEAR) spacecraft obtained 222 images of Eros, as well as supporting spectral observations. The images cover slightly more than two-thirds of Eros (best resolution is approximately 400 meters per pixel) and reveal an elongated, cratered body with a linear feature extending for at least 20 kilometers. Our observations show that Eros has dimensions of 33 x 13 x 13 kilometers. The volume, combined with the mass determined by the NEAR radio science experiment, leads to a density of 2.5 +/- 0.8 grams per cubic centimeter. This relatively high density, and the presence of an extensive linear feature, suggest that Eros may be a structurally coherent body.

Journal Article↗
PubMed1999

The United States liver donor population in the 1990s: a descriptive, population-based comparative study.

BACKGROUND: Orthotopic liver transplantation in the United States is primarily limited by a shortage of donor organs. METHODS: To better understand the low rates of organ donation in the United States and identify areas for potential improvement, we analyzed detailed demographic and mortality-specific data from 10,689 adult cadaveric liver donors obtained from the United Network for Organ Sharing from April 1, 1994 to March 31, 1997. Comparative U.S. population demographic and economic data were obtained from the U.S. census. RESULTS: As compared with the U.S. population, we found there to be significantly fewer nonwhite (P=0.001) and foreign-born donors (P=0.001); 58.9% of liver donors were male (P=0.001). The mean age was 40.6 years; yet during the 3-year period analyzed, there was a significant trend toward increasing age of donors. Median household income was 18% to 32% lower in the donor population than in the general U.S. population. In 91.2% of cases, the donor cause of death was listed as cerebrovascular stroke or head trauma. Numerous significant interracial differences were found in both the donor mechanism and circumstance of death. These included black donors being more likely to have gunshot wound as the listed mechanism of death (P=0.001) and to have homicide as the listed circumstance of death (P=0.001). CONCLUSIONS: Nonwhites and foreign-born individuals are significantly underrepresented in the U.S. liver donor population. Furthermore, donors seem to be poorer than the general U.S. population. Increasing the liver donor pool, especially among minorities, will require creative and thoughtful public initiatives.

Adolescent↗
PubMed1999

A simple model to estimate survival after retransplantation of the liver.

To formulate a model predicting survival after liver retransplantation, we analyzed in detail the last 150 cases of hepatic retransplantation at UCLA. Cox proportional hazards regression analysis identified five variables that demonstrated independent simultaneous prognostic value in estimating patient survival after retransplantation: (1) age group (pediatric or adult), (2) recipient requiring preoperative mechanical ventilation, (3) donor organ cold ischemia > or =12 hr, (4) preoperative serum creatinine, and (5) preoperative serum total bilirubin. The Cox regression equation that predicts survival based on these covariates was simplified by assigning individual patients a risk classification based on a 5-point scoring system. We demonstrate that this system can be employed to identify a subgroup of patients in which the expected outcome is too poor to justify retransplantation. These findings may assist in the rational selection of patients suitable for retransplantation.

Adult↗
PubMed1999

[Gaining new knowledge in clinical practice].

A study of the diffusion of knowledge about Helicobacter pylori and gastrointestinal disease among Norwegian clinicians is reported. A questionnaire about when and how research results on Helicobacter pylori and gastrointestinal disease were taken up by doctors in their practice was sent to 200 general practitioners and 200 medical and surgical gastroenterologists. This Norwegian study is part of a comparative study of the uptake process in the five Scandinavian countries which is planned to be published in an international journal. The specialists both heard of research results and started using new treatments earlier than the general practitioners. The main sources of information for the general practitioners were the national medical journal and courses or conferences, whilst the specialists obtained their information mainly from international journals and courses or conferences. The general practitioners were more likely to treat Helicobacter pylori positive dyspepsia and to use serology as a diagnostic tool, whilst the specialists were more likely to use breath tests and had a greater belief in the role of Helicobacter pylori as a cause of gastric cancer. The great majority of both groups knew of Helicobacter pylori as a cause of peptic ulcer disease, used antibiotics in its treatment, and preferred (referral to) endoscopic biopsy as the main diagnostic tool.

Adult↗
PubMed1999

Opioid substitution to reduce adverse effects in cancer pain management.

OBJECTIVE: To assess the effect of opioid substitution (substituting one member of the opioid class for another) on the incidence and severity of adverse effects in palliative care patients who experience unacceptable, refractory adverse effects when taking an opioid drug. DESIGN: Prospective audit of clinical records. SETTING: Palliative Care Program, Monash Medical Centre, Melbourne, Victoria (comprising an acute 10-bed palliative care unit and a palliative care consultative service). PATIENTS: All palliative care inpatients and patients referred to the consultative service who underwent opioid substitution between February 1996 and June 1997. OUTCOME MEASURES: Adverse effects and pain control profiles before and after opioid substitution. RESULTS: 55 opioid substitutions were undertaken in 49 patients. 49 substitutions were for adverse effects. The substitution produced partial or complete relief from confusion in 18 of 25 cases, from nausea and vomiting in 13 of 19, and from drowsiness in 8 of 15. Substitution also abolished myoclonus associated with renal failure in one patient. CONCLUSION: We found that the incidence and severity of adverse effects differed between opioids in the same patient. A trial of opioid substitution (usually in consultation with a specialist pain or palliative care unit and with auditing of outcomes) should be considered for patients with intolerable, refractory adverse effects of opioids.

Aged↗