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Biomedical subjects

J C Johnson

Publications and source records attributed to J C Johnson.

At least 91 records · Page 5Linked to original sources
PubMed1993

Magnetic resonance and positron emission tomography imaging of the corpus callosum: size, shape and metabolic rate in unipolar depression.

Magnetic resonance imaging (MRI) and positron emission tomography (PET) with fluorodeoxyglucose were used to study the size and shape of the corpus callosum in 20 patients with unipolar depressive disorder and 16 normal controls. An automated algorithm outlined the corpus callosum and divided it into quarters. The anterior and posterior quarters of the corpus callosum were larger in depressed patients than in controls, findings similar to most earlier MRI studies of the corpus callosum in schizophrenics. The patient-normal difference was more marked in females than in males. PET glucose metabolic values were higher in patients with thinner or smaller callosums. The presence of marked sex differences makes future larger studies controlling body size and age important.

Adult↗
PubMed1993

Ability of paramedics to use the Combitube in prehospital cardiac arrest.

STUDY OBJECTIVE: To evaluate the ability of paramedics in a nonurban emergency medical services system to use the Combitube, a combined endotracheal and esophageal obturator airway adjunct, in prehospital cardiac arrest patients. DESIGN: A prospective, controlled study to evaluate the difficulty and complications of insertion, recognition of esophageal versus tracheal placement, skill proficiency, and retention. The ability to use the device in cases of failed endotracheal intubation also was scrutinized. SETTING: Evaluation of the paramedic's ability to use the Combitube was performed in a prehospital environment. A follow-up study to determine retention of insertion skill was conducted in a controlled laboratory setting. INTERVENTIONS: Fifty-two cases of paramedic prehospital Combitube insertion were examined, and 11 paramedics were evaluated for skill retention. MEASUREMENTS AND MAIN RESULTS: Combitube insertion was attempted on 52 prehospital patients in cardiac arrest, and 69% were intubated successfully. Paramedics recognized esophageal versus tracheal placement in 100% of the cases. The Combitube was inserted successfully into 64% of the patients who could not be endotracheally intubated by the conventional visualized method. The Combitube was inserted successfully 71% of the time when used as a first-line airway adjunct. A follow-up study on 11 randomly selected paramedics involved in the field study was conducted 15 months later. Nine of 11 paramedics demonstrated inadequate skill retention in the follow-up study. CONCLUSION: Although visualized endotracheal intubation remains the preferred method of airway control, the Combitube may be an effective prehospital airway device as both a backup to the endotracheal tube and a primary airway. Although the Combitube does not require visualization with a laryngoscope, comprehensive training and continuing education are key factors affecting skill retention.

Emergency Medical Services↗
PubMed1993

Molecular characterization of the DNA of Anatid herpesvirus 1.

A plaque-purified isolate of the Holland strain of Anatid herpesvirus (AHV-ppc3) was purified by differential and buoyant density sedimentation. The virus buoyant density was 1.215 g/cm3 in sucrose. AHV-ppc3 DNA was analyzed by sedimentation velocity studies in neutral or alkaline sucrose gradients. Based upon a comparison with T4 DNA, the DNA of AHV-ppc3 was found to have a sedimentation coefficient of 59.7 S and a molecular mass of 1.19 x 10(8) daltons. Between 15 and 22 bands were observed in agarose gel electrophoresis with AHV DNA cut by BamHI, EcoRI, PstI or BglII. The possibility of isometric forms is indicated by the finding of restriction fragments having molar ratios differing from 1.0. The mean molecular mass calculated from the fragments was 1.18 x 10(8) daltons. Terminal fragments were identified using exonuclease II and BgII. In alkaline sucrose gradients, AHV DNA fragments with the largest of the most abundant species have a sedimentation coefficient of 69 S and a calculated mass of 6.0 x 10(7) daltons. The buoyant density of AHV-ppc3 DNA in cesium chloride was 1.723 g/cm3 corresponding to a % G + C content of 64.3. This finding was supported by thermal melts of the DNA in SSC/10 in which the thermal melting point was 82.7 degrees. The data support a model for AHV in which the viral duplex DNA is linear, without covalently closed termini or significant base modifications, but with single strand nicks or gaps. The % G + C content of AHV DNA is the highest reported for any avian herpesvirus in the alpha-herpesvirinea subgroup.

Animals↗
PubMed1993

Delirium.

Explore the source record for details and available documents.

Aged↗
PubMed1993

Knowledge, attitudes, and practices of obstetricians-gynecologists regarding the prevention of human immunodeficiency virus infection.

OBJECTIVE: To determine the knowledge, beliefs, attitudes, and practices of obstetricians-gynecologists regarding human immunodeficiency virus (HIV) prevention. METHODS: Office-based obstetricians-gynecologists in the Washington, DC metropolitan area who reported providing primary care were interviewed by telephone. The survey response rate was 62% (N = 268). RESULTS: The percentages of obstetricians-gynecologists who reported regularly assessing the HIV risk of new adolescent and adult patients were 67 and 40%, respectively. Seventy-two percent reported regularly counseling patients at risk to use condoms for vaginal intercourse, and 60% regularly counseled patients at risk to limit their number of sexual partners. The level of general risk-factor assessment and confidence in the ability to reduce patients' HIV risk were the strongest correlates of the frequency and thoroughness of HIV risk assessment and counseling. CONCLUSIONS: The percentage of obstetricians-gynecologists who assess and counsel patients about HIV risks is below the 75% goal for the year 2000 established by the United States Department of Health and Human Services. Continuing medical education for obstetricians-gynecologists is needed to improve their knowledge and skills in HIV prevention.

Adult↗
PubMed1993

General concepts of geriatric medicine.

To ensure the maximum quality of life for the elderly, practitioners must be precise in their evaluations. Physiologic aging decreases the reserve of the geriatric patient, making him or her more susceptible to the stress associated with illness, drugs, and surgery. Medications must be prescribed in reduced dosages to compensate for altered pharmacokinetics and pharmacodynamics in the elderly. Musculoskeletal problems, cardiovascular diseases, malignancies, and visual and hearing impairments are seen frequently in this population. Cognitive failure, depression, gait instability and falling, and urinary incontinence may be caused by acute or chronic problems. A comprehensive assessment directed at medical, mental, social, and functional status problems is imperative.

Aged↗
PubMed1992

Prognostic significance of polymerase chain reaction detected human papillomavirus of tumors and lymph nodes in surgically treated stage IB cervical cancer.

This study describes the prognostic role of polymerase chain reaction detected human papillomavirus (HPV) in Stage IB cervical cancer patients treated with radical hysterectomy and pelvic and paraaortic node dissection. All tumors were confined to the cervix and all margins and nodes were disease free. Twenty-one patients were analyzed: 6 patients recurred within 20 months of initial therapy, while 15 had no evidence of disease with a minimum follow-up of 36 months. Polymerase chain reaction (PCR) was performed on paraffin-block tissue of the hysterectomy specimen cervical tumor and lymph nodes. Oligonucleotide probes for HPV types 6, 11, 16, 18, 31, 33, and 35 were used with consensus primers for uncharacterized HPV types created from an L1 constant region. Control tissues were run with each tumor sample to assure against contamination. HPV type confirmation was performed using diagnostic restriction sites. HPV was detected in all cervical tumors. Recurring tumors were infected with multiple types of HPV in all 6 tumors versus only 5 of 15 nonrecurring tumors being multiply infected (P = 0.023). No tumor had HPV 6 or 11, and the incidence of HPV 16, 31, 33, and 35 was not significantly different for recurrent versus nonrecurrent groups. HPV 18 was found in 5 of 6 recurring cancers versus 1 of 15 nonrecurring tumors (P = 0.0029). PCR typing of the histologically negative nodes that had been obtained at radical hysterectomy was done in all 6 recurring patients and in 6 nonrecurring patients. The recurrent patients had a significantly higher incidence of lymph nodes positive for HPV DNA (71%) than the nonrecurring patients (35%) (P = 0.0047). These observations suggest that HPV 18 cervical cancer patients, those with infections of multiple types, and those with HPV DNA in histologically negative lymph nodes may be at increased risk for recurrence.

Adult↗
PubMed1992

High frequency of latent and clinical human papillomavirus cervical infections in immunocompromised human immunodeficiency virus-infected women.

In 32 human immunodeficiency virus (HIV)-infected women, routine gynecologic examination was performed with colposcopy and Papanicolaou smear; cervical swabs were collected for human papillomavirus (HPV) DNA screening and typing; and immune status was assessed by CD4 T-cell count. Dot blot analysis was specifically chosen for HPV DNA screening to detect only relatively substantial HPV DNA infections. Polymerase chain reaction analysis was used for precise DNA typing of dot blot-positive samples. The HPV data were assessed for immune status; a subject with a CD4 T-cell count below 200/microL was considered functionally immunosuppressed. The frequency of dot blot positivity was fivefold higher among immunocompromised (nine of ten) than relatively immunocompetent (four of 22) HIV-infected women. Moreover, four immunosuppressed women, compared with no immunocompetent subjects, had evidence of HPV DNA without signs of HPV-associated lesions by cytology or histology (ie, latent HPV infection). Furthermore, four of nine of the immunocompromised, compared with four of 21 immunocompetent, subjects had cervical intraepithelial neoplasia. These frequencies are high compared with those reported in the general population. Finally, HPV 18 was detected in five of the ten women with CD4 T-cell counts below 200/microL and in only one of the 22 with CD4 T-cell counts above that level. These results suggest that the normal immune system suppresses latent and clinical HPV cervical infections and that the efficiency of suppression may be HPV type-specific. Furthermore, impaired immune status, as reflected by CD4 T-cell count, is an important factor increasing the severity of HPV-induced cervical infections in this population.

Adult↗
PubMed1992

Prospective versus retrospective methods of identifying patients with delirium.

OBJECTIVE: To determine if DSM-III criteria or clinical or discharge diagnoses, reviewed retrospectively, are as accurate an indicator of the presence of delirium as prospective evaluation by a psychiatrist. DESIGN: Selection of delirious patients prospectively by a psychiatrist, followed by retrospective record review of the same patients. SETTING: A referral-based university hospital. PATIENTS: From a sample of 235 consecutive medical patients over age 70, 47 delirious patients were identified prospectively by a research psychiatrist using DSM-III criteria. The medical record of these delirious patients was reviewed after discharge for evidence of delirium. RESULTS: Four patients were assigned ICD-9 codes suggestive of delirium (sensitivity 0.09). Review of physicians' diagnoses correctly identified 8 of 47 (sensitivity 0.17) patients as being delirious or acutely confused. The specific diagnostic criteria necessary to meet a DSM-III diagnosis of delirium could be ascertained from 10 of 47 records (sensitivity 0.21). CONCLUSION: The retrospective medical record review is very imprecise in establishing the diagnosis of delirium. As research in this field moves from descriptive epidemiology to studies of pathogenesis and treatment, prospective designs will be needed.

Abstracting and Indexing↗
PubMed1992

Functional status outcomes of a nursing intervention in hospitalized elderly.

This paper examines the effectiveness of a nursing intervention for elderly hospitalized patients (N = 235) as measured by functional outcomes. A nursing intervention targeted at factors which influence acute confusion or delirium employed strategies to educate nursing staff, mobilize patients, monitor medication and make environmental and sensory modifications. Subjects who received the intervention were more likely to improve in functional status from admission to discharge than subjects who did not receive the intervention.

Activities of Daily Living↗
PubMed1992

Effect of sleep deprivation on brain metabolism of depressed patients.

OBJECTIVE: Sleep deprivation is a rapid, nonpharmacologic antidepressant intervention that is effective for a subset of depressed patients. The objective of this study was to identify which brain structures' activity differentiates responders from nonresponders and to study how metabolism in these brain regions changes with mood. METHOD: Regional cerebral glucose metabolism was assessed by positron emission tomography (PET) with [18F]deoxyglucose (FDG) before and after total sleep deprivation in 15 unmedicated awake patients with unipolar major depression and 15 normal control subjects, who did the continuous performance test during FDG uptake. RESULTS: After sleep deprivation, four patients showed a 40% or more improvement on the Hamilton Rating Scale for Depression. Before sleep deprivation the depressed responders had a significantly higher cingulate cortex metabolic rate than the depressed nonresponders, and this normalized after sleep deprivation. The normal control subjects and nonresponding depressed patients showed no change in cingulate metabolic rate after sleep deprivation. CONCLUSIONS: Overactivation of the limbic system as assessed by PET scans may characterize a subset of depressed patients. Normalization of activity with sleep deprivation is associated with a decrease in depression.

Adult↗
PubMed1992

Calculation of radiation dose at a bone-to-marrow interface using Monte Carlo modeling techniques (EGS4)

Radiation dose rate profiles at a bone-to-marrow interface were calculated by simulating a uniform radiation source at the center of the endosteal layer in a long bone. Isotopes (153Sm, 186Re, and 166Ho) were assumed to assimilate as surface agents and the dose profiles were calculated on a microscopic scale using the Electron-Gamma Shower (EGS4) computer program. We validated our computational model against published dose factors (delta) for uniform volume distributed sources replicating them to an accuracy of better than 95%. The calculated dose distributions illustrate the relative contribution of atomic electrons, beta, and photon fractions. The backscatter contribution to marrow dose increased from 3% to 4% at the source to 6% to 8% at a marrow depth of 100 microns. Backscattered dose fraction was not significantly different among the three isotopes. The dose contribution from the three isotopes was remarkably similar at ranges between 25 and 125 microns.

Bone Marrow↗
PubMed1991

PET in generalized anxiety disorder.

Positron emission tomography (PET) measurements of cerebral glucose use were made in 18 patients with generalized anxiety disorder (GAD) during a passive viewing task off medication, and an active vigilance viewing task before and after medication or placebo treatment. In the passive viewing task, patients with GAD were compared with 15 normal controls. A significant difference in pattern of absolute brain metabolism was found. Patients showed lower absolute metabolic rates in basal ganglia and white matter. Relative metabolism was increased in the left inferior area 17 in the occipital lobe, right posterior temporal lobe, and the right precentral frontal gyrus. Significant left-right asymmetry of the parahippocampal gyri was not found in patients with GAD. An active vigilance task resulted in activation of relative basal ganglia metabolism in patients. Benzodiazepine therapy resulted in decreases in absolute metabolic rates for cortical surface, limbic system, and basal ganglia and was not associated with normalization of patterns of glucose metabolism. Change in anxiety scores was significantly correlated with change in limbic system and basal ganglia for the placebo group. The normal-anxious difference in the basal ganglia and the change seen in this region after benzodiazepine treatment are suggestive of a role in anxiety for this structure.

Adult↗
PubMed1991

Prehospital care: the future of emergency medical services.

Most prehospital interventions, both pharmacologic and procedural, have been accepted without clear demonstrations of their abilities to impact patient outcomes or without clear indications that withholding or delaying the intervention pending arrival at a definitive emergency department will adversely affect the patient. Interventions that have the benefit of supportive research have been applied equally to urban and nonurban emergency medical services environments. In selecting interventions, inadequate consideration has been given to the differences in emergency medical services personnel training, frequencies of their exposure to patients, frequencies of skill use, and availabilities of effective continuing education programs in the urban and nonurban environments. These issues are discussed, and the necessary focus of the future of emergency medical services in urban, suburban, and rural environments is predicted.

Clinical Competence↗
PubMed1991

Recombinant alpha-interferon and verruca plantaris. A review of the literature.

The authors review the literature and report the mechanisms of action, chemical properties, pharmacokinetics, adverse effects, and clinical studies of recombinant alpha-interferon. The authors believe that clinical trials should be performed with recombinant alpha-interferon therapy on verruca plantaris to prove or disprove the effectiveness of interferon as a potential treatment modality for these commonly encountered lesions.

Clinical Trials as Topic↗