Biomedical subjects

C Baker

Publications and source records attributed to C Baker.

At least 73 records · Page 4Linked to original sources

PubMed1996

Observations on the micromorphology of the tropical rat mite Ornithonyssus bacoti (Hirst) as revealed by scanning electron microscopy.

Ornithonyssus bacoti (Hirst) is an important parasite of rodents. The characteristic shape of the dorsal and sternal shields and gnathosoma used as taxonomic characteristics was confirmed by scanning electron microscopy. The anal plate is distinctly pear-shaped with a pair of adanal setae lateral to the anal valves, a single postanal seta and a distinct dentate cribrum formed by peg-like projections. In the adult mites a peritreme extends anteriorly to the 1st coxa from the spiracle situated laterally between the 3rd and 4th coxa. The peritreme is an open canal protected by an overhanging dorsal ridge and lined with short peg-like aciculae. The gnathosoma includes a pair of pedipalps, a pair of protrusile chelicerae retracted into the hypostoma, and a serrate tritosternum ventrally. A unique feature to the normal setae of the pedipalps is a golf club-shaped seta which is found medially on the palp genu. A distinctive double-bladed 'palpal claw' or apotele is directed medially from the palp tibia. The pincer-like chela consists of a spear-like prong forming the moveable digit and a curved stylus-like fixed digit used to pierce the skin. Each leg ends with a pair of hooked tarsal claws and a pair of lateral comblike pretarsal appendages adjacent to the pulvillus. The pulvillus may be retracted, allowing the pretarsal operculum to function as a 'clasping organ' that enables the mite to clasp the hairs of the host during feeding.

Animals↗

PubMed1995

Longevity and Medicare expenditures.

BACKGROUND: In the United States, the elderly account for over one third of health care spending. The total population over the age of 65 is projected to increase, as is life expectancy beyond the age of 65. We studied current patterns of Medicare expenses according to age at death and the possible effect of future demographic changes on Medicare spending. METHODS: We used data from the Medicare program to estimate lifetime Medicare expenses for a sample of 129,166 beneficiaries, 65 or older, who died in 1989 and 1990, according to age at death. Spending for nursing home care not covered by Medicare was excluded. (Nursing home costs represent about 20 percent of total health care spending for the elderly and increase with age.) Through simulation, we assessed the lifetime payments by Medicare for enrollees who turned 65 in 1990 and those who will do so in 2020. RESULTS: Estimated lifetime Medicare payments (in 1990 dollars) ranged from $13,044 for persons who died at 65 years of age, to $56,094 for those who died at 80, to $65,633 for those who died at 101 or older. The payments associated with an additional year of life and the average annual payments over an enrolle's lifetime both decreased as the age at death increased. The estimated 7.9 percent increase in life expectancy beyond 65 years that will have taken place between 1990 and 2020 (19.1 years past the age of 65 in 2020, as compared with 17.7 years in 1990) was associated with an estimated increase of 2.0 percent in lifetime Medicare payments. Of the estimated $98 billion increase in total lifetime payments (in 1990 dollars) from the 1990 group to the 2020 group, 74.3 percent was due to the larger size of the original birth cohort who will reach the age of 65 in 2020, 22.5 percent to an increase in the proportion of that birth cohort projected to survive to 65 years of age, and 3.2 percent to improved life expectancy beyond 65. CONCLUSIONS: The effect on Medicare spending of increased longevity beyond the age of 65 may not be great. Total Medicare payments will be more substantially affected by the expected increase in the absolute number of elderly people.

Aged↗

PubMed1995

Temporary back and leg pain after bupivacaine and morphine spinal anaesthesia.

Transient neurological symptoms have been reported after hyperbaric lidocaine 5% spinal anaesthetics. We report a patient with neurogenic back and leg pain after uncomplicated bupivacaine and morphine spinal anaesthesia. A healthy 39-yr-old woman received 1.6 ml hyperbaric bupivacaine 0.75% and 250 micrograms morphine intrathecally. Two hours later, the patient experienced discomfort during suturing of the peritoneum and surgery was completed under general anaesthesia. Recovery was uncomplicated until 13 hr after intrathecal injection, when the patient complained of burning pain in her back extending to the front of the abdomen and similar pain in her thighs. Neurological consultation was obtained. Treatment was started with amitriptyline and the symptoms resolved slowly. Complete recovery occurred over three months. Further studies to assess symptoms after spinal anaesthesia are indicated.

Adult↗

PubMed1995

Comparison of case-finding methodologies for endometritis after cesarean section.

BACKGROUND: Endometritis is a possible complication of delivery among patients undergoing cesarean section, resulting in increased costs and patient morbidity. However, traditional case-finding methods for endometritis may not identify most cases. We compared various case-finding methods with a reference method to determine a simple and accurate method for collecting data on endometritis after cesarean section. METHODS: We reviewed charts of all patients undergoing cesarean section (N = 167) during March 1 through July 31, 1991. These data were compared with study case-finding methods that used microbiology data, infection report forms from nursing, and computerized reports linking patients undergoing cesarean section with intravenous antibiotic use data and admission and discharge diagnoses. RESULTS: Each case-finding method was compared separately with the reference method ("gold standard"), which was designed to capture all cases among the patients in the study population (N = 145). This review yielded nine cases of endometritis (infection rate of 5.4/100 procedures). The computerized report method linking patients who underwent cesarean section with antibiotic use had a positive predictive value of 0.53. Methods that used microbiology data and nursing report forms had lower positive predictive values of 0.18 and 0.20, respectively. CONCLUSIONS: In our institution, case finding for postcesarean endometritis by means of a computerized report linking patients undergoing cesarean section with i.v. antibiotic use data and admission and discharge diagnoses is the most effective method of detecting postcesarean endometritis. It also represents the most efficient use of the infection control department's resources.

Anti-Bacterial Agents↗

PubMed1995

Feasibility, accuracy and safety of magnetic resonance imaging in acute aortic dissection.

Magnetic resonance imaging (MRI) is the most accurate method of defining the morphology and haemodynamic features of thoracic aortic dissection. However, because of doubts about its safety in acute situations, its use has so far been confined to imaging chronic dissections. We present a prospective study of 50 patients thought clinically to have acute thoracic aortic dissection in which a rapid diagnosis was made by MRI.

Acute Disease↗

PubMed1995

Carotid artery trauma: a review of contemporary trauma center experiences.

PURPOSE: Many issues surrounding the management and outcome of carotid artery injuries remain controversial. The purpose of this study was to review a large contemporary experience with such injuries in the setting of designated trauma centers. METHODS: A statewide computerized trauma registry was used to identify all patients with injuries to the common or internal carotid arteries from October 1987 to June 1993. The records of 82 such patients were retrieved and analyzed. RESULTS: Overall mortality and stroke rates were 17% and 28%, respectively. Patients presenting with coma or shock had a particularly bad prognosis (50% and 41% mortality, respectively). Internal carotid injuries resulted in mortality and stroke rates of 21% and 41%, respectively, compared with 11% each for common carotid injuries. Patients with blunt injuries had a much higher stroke rate (56% vs 15%) but had lower mortality (7% vs 22%) than did patients with penetrating injuries. Airway compromise and associated injuries did not affect prognosis. Operative repair and percutaneous balloon occlusion had the best survival and functional outcomes. CONCLUSIONS: Operative repair offers the best chances for recovery in all categories of patients regardless of injury mechanism. Ligation is useful only as a last-resort lifesaving effort. Shock and neurologic impairment are poor prognostic factors but should not negate repair.

Adolescent↗

PubMed1995

The development of the self-care ability to detect early signs of relapse among individuals who have schizophrenia.

A qualitative study using interpretive interactionism investigated how individuals with schizophrenia develop an ability to detect early signs of relapse. A purposive sample of 15 respondents were interviewed about their illness experiences. Three sequential processes were identified. Responding reactively to psychic pain, initiated by a desire to escape from overwhelming distress, resulted in the differentiation of tolerable and intolerable pain. Refining perceptions of psychic pain followed and resulted in the identification of specific thoughts, feelings and behaviors associated with different levels of distress. Finally, actively reducing psychic pain resulted in a proactive surveillance for specific signs of increasing distress.

Adolescent↗

PubMed1995

Core temperature control in the management of CNS lesions.

Renewed interest in the regulation of core temperature as a means of treating central nervous system disease has been fueled by a wealth of literature describing the physiology of lowered core temperature. Hypothermia is now recognized for its anesthetic and cerebroprotective effects and is being applied in an increasing number of clinical paradigms.

Body Temperature↗

PubMed1995

Diagnostic criteria for screening headache patients for temporomandibular disorders.

Patients with temporomandibular disorders frequently suffer from headache. The purpose of this study was to develop a simple screening exam which would allow the physician to identify headache patients with coexisting temporomandibular disorders. Twenty-eight migraine and 27 tension headache patients were identified by a board certified neurologist and then were examined by a dentist for signs of temporomandibular disorders. These patients were then compared to 63 patients with temporomandibular internal derangements and 62 patients with myofascial pain dysfunction. Comparisons of the clinical signs showed that the temporomandibular internal derangement and myofascial pain dysfunction patients differed significantly from the headache patients in regards to specific signs of jaw dysfunction. The presence of reciprocal clicking of the temporomandibular joint or pain with maximum jaw opening and pain upon palpation of the temporomandibular joint distinguished temporomandibular internal derangement patients from headache patients. These criteria have a sensitivity of 92% and specificity of 91%. Pain on palpation over the temporomandibular joint, or pain with maximum jaw opening using passive stretch, and pain with lateral movement of the jaw, distinguished myofascial pain dysfunction patients from headache patients. These criteria have a sensitivity of 77% and specificity of 85%. By using these screening tests, the physician can identify the concurrent existence of temporomandibular disorders in headache patients and triage the patient to a clinician knowledgeable in the diagnosis and treatment of temporomandibular disorders for further evaluation.

Cross-Sectional Studies↗

PubMed1995

A functional status scale for measuring quality of life outcomes in head and neck cancer patients.

Increased survival rates and disease control dictate that quality of life after treatment for head and neck cancer be evaluated. A disease-specific measure was developed from interviews with 115 patients, and items reflect the terminology used by the patients to describe treatment-related problems and concerns. Validity and reliability of this self-report scale were tested with 172 head and neck cancer patients and 30 patients who had breast and gynecological cancers. Discriminate validity was excellent. Convergent validity of the scale was demonstrated by Pearson correlations of 0.68 with a general health status measure, 0.68 with the Karnofsky Performance Scale, and 0.76 with the Performance Status Scale for Head and Neck Cancer Patients. Reliability as measured by Cronbach's alpha was 0.88. Analysis of variance demonstrated that the scale was sensitive to differences in stage of disease (p = 0.017) and extent of first surgery (p = 0.001) in this cohort of head and neck cancer patients. Psychometric evaluation indicates that the scale could be used as an outcome measure between groups at one point in time, but future research is needed to establish the scale's sensitivity to positive and negative changes in functional status for longitudinal studies.

Adult↗

PubMed1994

The effects of ozone exposure on lactate dehydrogenase release from human and primate respiratory epithelial cells.

Ozone is the most persistent, wide-spread air pollutant in the United States. Over one half of the population of the US lives in cities or suburban areas which do not meet the National Ambient Air Quality Standard for ozone which is 0.12 ppm averaged over 1 h. Controlled laboratory exposures of human subjects have shown that ozone exposure produces decreased pulmonary function, hyperresponsiveness to inhaled methacholine, inspiratory pain, and airway inflammation as assessed by bronchoalveolar lavage. However, the cellular mechanisms responsible for such effects are incompletely known. The present study examined the effects of ozone exposure at 0.50 ppm for 3 h on three types of cultured respiratory epithelial cells; primary cultures of human nasal cells and primate bronchial cells, and the A549 type II pneumocyte-derived cell line. Cells were grown to confluent monolayers in plastic 6-well plates and then exposed to ozone or filtered air on a tilting platform over a heated water bath. Lactose dehydrogenase release was significantly increased following ozone exposure of all cell types; a 75% increase from human nasal cells (P = 0.0002), a 79% increase from primate bronchial cells (P = 0.003), and a 69% increase from A549 cells (P = 0.02). These data suggest that even brief ozone exposure causes membrane injury to cultured human respiratory epithelial cells.

Adolescent↗

PubMed1994

Studies of the epidemiology of dementia: comparisons between developed and developing countries.

By the year 2025, 68% of the world's population aged 65 and above, nearly 277 million people, will be residing in developing countries. The less industrialized nations have been the least studied to date, and may yield significant new information about the etiology and risk factors for Alzheimer's disease (AD) and other dementias. Although it is readily apparent that cross-national and cross-cultural comparisons are desirable, these can be meaningful only if based on comparable methodology. In this work we will discuss some general conceptual and methodological issues regarding epidemiological studies of dementia in developing countries. The topics discussed include community-based screening for dementia, screening instruments and their application in cross-cultural studies, steps in standardization of new or modified neuropsychological tests, and some special considerations in studying uneducated/illiterate populations.

Aged↗

PubMed1994

Sexual communication is associated with condom use by sexually active incarcerated adolescents.

PURPOSE: Incarcerated adolescents are at increased risk for infection by sexually transmitted diseases (STDs), including human immunodeficiency virus (HIV). Moreover, condom use by this population is extremely low. Although interpersonal variables such as sexual communication have been found to be associated with condom use in other populations, few researchers have investigated this relationship among adolescents requiring detention in juvenile facilities. The present study investigated the relationship between communication about sexual history and incarcerated adolescents' condom use. METHODS: We used multivariate logistic regression techniques to analyze interview data from a predominantly Latino sample of 2,132 sexually active adolescents detained in Los Angeles County Juvenile Hall. RESULTS: Despite high numbers of lifetime sexual partners, a substantial majority of respondents (67%) reported that they never used condoms during sexual intercourse. Respondents who communicated with their sex partner(s) about each others' sexual history were significantly more likely to use condoms during sexual intercourse. Adolescents who reported that they knew someone with AIDS were also more likely to use condoms. CONCLUSIONS: Interventions designed to increase condom use among sexually active incarcerated adolescents should include a component addressing sexual communication practices. More research is needed on the ways in which adolescents learn to communicate about sex.

Adolescent↗

PubMed1994

Synthesis of interleukin-1 alpha, interleukin-6, and interleukin-8 by cultured human nasal epithelial cells.

Nasal epithelium forms the initial barrier between the environment and the respiratory system and may be a potential source of proinflammatory interleukins, which contribute to the pathophysiology of allergic and nonallergic rhinitis. To explore this possibility, epithelium and cultured human nasal epithelial cells from nasal turbinates of patients undergoing surgery for treatment of upper airway obstruction were examined for the spontaneous expression of interleukin (IL)-1 alpha, IL-1 beta, IL-6, and IL-8. Human nasal epithelial cell lysates and culture supernatants were assayed by two-site ELISAs specific for IL-1 alpha, IL-1 beta, IL-6, or IL-8. Maximum concentrations of these cytokines in supernatants ranged from approximately 0.2 to 2 ng/ml for IL-1 alpha, 1.5 to 7 ng/ml for IL-6, and 100 to 3000 ng/ml for IL-8. IL-1 alpha was predominantly cell-associated, whereas most of the IL-8 and all of the IL-6 were detected in the supernatant. Little or no IL-1 beta was detected by ELISA in the supernatants or cell lysates. Whole tissue turbinates and isolated epithelium were also examined for IL-1 beta, IL-6, and IL-8 mRNA expression by Northern blot analysis. IL-6 and IL-8 mRNAs were detected, whereas IL-1 beta mRNA was not. Furthermore, IL-6 and IL-8 release from human nasal epithelial cell cultures was enhanced by addition to the cultures of lipopolysaccharide, and IL-6 release was inhibited by polymyxin B. Thus human nasal epithelium may be a major source of IL-1 alpha, IL-6, and IL-8 in allergic and nonallergic rhinitis. Production of those proinflammatory cytokines by epithelial cells of the nasal and sinus mucosa may contribute to the pathologic and clinical events that occur in these diseases.

Adolescent↗

PubMed1994

Arthroscopic treatment of anterolateral ankle impingement.

Fifty-five ankle arthroscopies performed for anterolateral ankle impingement between January 1987 and April 1992 were reviewed for functional outcome and patient satisfaction. There were 33 men and 22 women with an average age of 34 years (range 20-67). All patients reported a previous history of ankle injury, and 60% of the patients had at least one ankle sprain. At an average follow up of 2.6 years (range 1.0-4.5), 87% of the patients had good/excellent results, 98% were satisfied, and 84% returned to their previous sports.

Adult↗

PubMed1994

Resettlement without the support of an ethnocultural community.

The purpose of this phenomenological study is to describe the lived experience of immigrating to a region where there is no ethnocultural community of one's culture. Twenty culturally isolated immigrants to Moncton, New Brunswick, Canada, of different ethnic origins were interviewed in depth about their resettlement experience: the Giorgi modification of the phenomenological method was used to analyse these data. The findings suggest that being a culturally isolated immigrant entails a sense of discontinuity between the past and the present and produces a period of heightened sensitivity to others. Informants felt propelled from their country into an alien environment and were suddenly immersed into a new culture. Their emotional energies were directed towards getting a foothold in their new society. This was a highly stressful process that was both encouraged and discouraged by pervasive thoughts of the future which permeated the participants' existence.

Adult↗

PubMed1994

Prevalence of Neisseria meningitidis relatively resistant to penicillin in the United States, 1991. Meningococcal Disease Study Group.

To estimate the prevalence of Neisseria meningitidis relatively resistant to penicillin in the United States, antimicrobial susceptibility testing was performed on all US meningococcal isolates submitted to the Centers for Disease Control and Prevention in 1991, including isolates identified through population-based surveillance for invasive meningococcal disease in selected areas of the United States. Three of the 100 isolates tested had MICs of penicillin of 0.125 microgram/mL. All were serogroup B, beta-lactamase-negative, and unique by multilocus enzyme electrophoresis subtyping. None of the 3 patients had been treated solely with penicillin; all recovered completely. About 4% of the isolates obtained from the population-based surveillance system were relatively penicillin-resistant. Given the low prevalence and uncertain clinical significance of infection with these organisms, routine susceptibility testing of meningococcal isolates is not indicated at this time; however, continued surveillance is necessary to monitor trends in antimicrobial susceptibility of meningococci in the United States.

Disease Outbreaks↗

PubMed1993

Cytokines and eosinophil-derived cationic proteins upregulate intercellular adhesion molecule-1 on human nasal epithelial cells.

BACKGROUND: Allergic and nonallergic rhinitis with eosinophilia syndrome are characterized by tissue eosinophilia and nasal mucosal injury. Recently, it has been shown that the adherence of eosinophils and other leukocytes to epithelial cells is mediated by intercellular adhesion molecule-1 (ICAM-1) and related adherence-promoting glycoproteins. METHODS: In this study we examined the constitutive expression of ICAM-1 on human nasal epithelial cells (HNECs), and the effects of interferon-gamma, tumor necrosis factor-gamma eosinophil major basic protein, and eosinophil cationic protein on the regulation of ICAM-1 expression on these cells. Similar studies were performed with A549 pneumocytes as comparative epithelial cells. RESULTS: Constitutive expression of ICAM-1 was significantly higher on cultured HNECs than on A549 cells, although nasal epithelial cells in tissue specimens did not demonstrate detectable levels of ICAM-1. This spontaneous expression of ICAM-1 on cultured HNECs may explain the unique susceptibility of the nasal mucosa to rhinovirus infection, because ICAM-1 is the epithelial cell receptor for most rhinoviruses. Physiologic concentrations of major basic protein and eosinophil cationic protein stimulated significant upregulation of ICAM-1 on HNECs, which was comparable to that produced by interferon-gamma and tumor necrosis factor-alpha. In contrast, these eosinophil constituents did not stimulate ICAM-1 upregulation on A549 alveolar epithelial cells, although A549 cells did respond to interferon-gamma and tumor necrosis factor-alpha. CONCLUSION: The observation that eosinophil products upregulate ICAM-1 on HNECs suggests a positive feedback mechanism, in which the products released from migrating eosinophils might promote additional HNEC-leukocyte adherence by enhancing interactions between leukocyte beta 2 integrins (CD11/18) and nasal epithelial ICAM-1.

Blood Proteins↗