Thermodynamic stability of Kerr black holes.
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Journal Article↗
Biomedical subjects
J Katz
Publications and source records attributed to J Katz.
Lifetime prevalence of ocular injuries from the Baltimore Eye Survey.
OBJECTIVE: To estimate the cumulative lifetime prevalence, nature, and consequences of ocular injuries in a multiracial urban environment. METHODS: Self-reported lifetime ocular injuries were ascertained in a population-based sample of persons aged 40 years or older residing in 16 clusters in east Baltimore, Md. A total of 5308 subjects underwent a screening eye examination and were interviewed about lifetime ocular injuries. RESULTS: Eight hundred thirty ocular injury incidents were reported by 762 (14.4%) subjects. The maximum number of ocular injuries reported in a lifetime was four. At least one injury was reported by 22.5% of black men, 20.3% of white men, 12.2% of black women, and 7.7% of white women. No treatment was sought for 18% of these injuries (22% black and 14% white subjects). The prevalence of visual impairment due to trauma per 1000 people was 22.3 among black men, 7.4 among white men, 6.7 among black women, and 3.5 among white women. The prevalence of blindness due to trauma in at least one eye was 21.2 per 1000 among black men, 3.7 times the rate among white men. Based on reports of injuries in the year prior to interview, the annual incidence of medically treated ocular injuries per 1000 people was 5.6 among black men, 4.1 among white men, 5.3 among black women and 1.8 among white women aged 40 years and older. CONCLUSIONS: Lifetime prevalences of ocular injuries were similar among both black and white men, but the visual consequences of the injuries were more severe among black men.
Adolescent↗
Major histocompatibility complex class I molecules are required for the development of insulitis in non-obese diabetic mice.
An early step in the development of autoimmune diabetes is lymphocyte infiltration into the islets of Langerhans of the pancreas, or insulitis. The infiltrate contains both CD4+ and CD8+ T cells and both are required for progression to diabetes in non-obese diabetic (NOD) mice. It has been thought that the CD4+ lymphocytes are the initiators of the disease, the islet invaders, while CD8+ cells are the effectors, the islet destroyers. We question this interpretation because NOD mice lacking MHC class I molecules, hence CD8+ T cells, do not display even insulitis when expected.
Animals↗
The effect of D2O on glycolysis by rat hepatocytes.
1. The effect of incorporating D2O into the incubation medium on glycolysis and gluconeogenesis by hepatocytes from fasted rats was examined. 2. The substitution by heavy water, D2O, at concentrations from 10 to 40%, stimulated glucose uptake, lactate production and CO2 yields from glucose. At 10 mM glucose, 40% D2O doubled glucose uptake, increased CO2 production by 40%, and increased lactate production by 350%. 3. The stimulation of lactate production decreased at higher glucose concentrations, but was still substantial even at 80 mM glucose. 4. There was no effect on CO2 production above glucose concentrations of 30 mM. 5. Ten percent D2O showed little inhibition of lactate uptake, its oxidation and gluconeogenesis. At 40% D2O the inhibition ranged from 10 to 20%. 6. No effect of D2O on the rate of glucokinase or glucose-6-phosphatase was observed. 7. The concentration of fructose, 2,6-P was not affected by D2O.
Animals↗
A concentration gradient of glucose from liver to plasma.
Concentrations of glucose in plasma water and liver water were determined in rats under a number of conditions. In fasted and fed postadsorptive rats, the concentration of glucose in plasma water averaged 5.5 +/- 0.5 and 6.8 +/- 0.2 mmol/L, respectively. The concentration in liver water was 8.2 +/- 0.9 and 11.1 +/- 1.1 mmol/L, respectively (mean +/- SD). The concentration ratio of liver water to plasma water (LW/PW) was 1.52 +/- 0.1 (range, 1.4 to 1.7; n = 7) in fasted rats and 1.64 +/- 0.39 (range, 1.38 to 2.0; n = 10 [mean +/- SD]) in fed rats. Fasted rats treated with glucagon contained no liver glycogen. The concentration of glucose in plasma water was 7.1 +/- 0.3 mmol/L and in liver water 9.2 +/- 0.5 mmol/L, and the LW/PW averaged 1.35 +/- 0.08 (range, 1.23 to 1.45; n = 8). Insulin-injected hypoglycemic rats contained very little glycogen. The LW/PW was 2.7 +/- 0.2. In fasted rats infused intragastrically with 30 mg/min/kg glucose, the concentration of glucose in mixed portal-arterial plasma water entering the liver averaged 10.3 +/- 0.8 mmol/L and that in liver water 12.4 +/- 1.3 mmol/L (mean +/- SD), with the LW/PW averaging 1.21 +/- 0.1 (range, 1.08 to 1.4; n = 8). Fasted rats were infused with 3.4 mg/min/kg sodium lactate labeled with 14C and 13C and with a trace amount of [3-3H]glucose. The glucose concentration in arterial plasma water averaged 6.4 +/- 1.0 mmol/L and in liver water 14.6 +/- 4.4 mmol/L (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
A mathematical model of the right ventricular muscle geometry and mass.
An understanding of the geometry of the right ventricular (RV) free wall is imperative for both modelling its mechanics and assessing its mass by imaging techniques such as echocardiography. In this paper, a new model of the RV free wall geometry is discussed in which the wall is assumed to have a parabolic long-axis and a circular short-axis curvature respectively. By use of analytic geometry, mathematical expressions for RV surface area, volume and mass were derived. In vitro model validation was carried out in the following manner: (1) echocardiographic images of 16 isolated calf hearts were obtained; (2) measurements were made from the images to determine the parameters required by the model; (3) wall mass was determined by use of these parameters; and (4) the calculated wall mass was then compared with actual RV wall mass (determined by weighting). The model was found to be very accurate for determination of RV free wall mass (R = 0.92); it should prove useful in the study of the stress-strain relationships for the RV and for precise quantitative assessment of RV free wall mass.
Animals↗
A new geometric description of the right ventricle.
An accurate model of the geometry of the right ventricle would be particularly useful for volume determination by imaging techniques, as well as for mechanical modelling. In this study, a new mathematical model for the right ventricle geometry based on its crescentic cross-sectional shape is proposed and used to calculate its volume in imaged ex-vivo casts. An excellent correlation (r = 0.97) was found between volume as derived from the model and actual volume measured by water displacement.
Cardiac Volume↗
Anterior lingual mandibular salivary gland defect--a dilemma in diagnosis.
Anterior lingual mandibular salivary gland defects are very rare. These lesions present as non-definitive bony radiolucencies. There are several other radiolucent entities which present in the anterior mandible with greater frequency and this creates a diagnostic dilemma for the practitioner. The ultimate and proper treatment of non-treatment depends on a correct diagnosis of these lesions. The correctness of the diagnosis and avoidance of unnecessary traumatic procedures may be aided by more sophisticated radiographic studies, such as a CAT scan and/or Magnetic Resonance Imaging. A case of a very unusual appearing anterior lingual mandibular salivary gland defect is presented and the diagnosis, management and recommendation for more complex radiographic studies are discussed.
Choristoma↗
Estimation of myocardial water content using transverse relaxation time from dual spin-echo magnetic resonance imaging.
Dual spin-echo magnetic resonance imaging may be used for calculation of transverse myocardial relaxation time from the signal intensity of the echoes considered. In this study, the ability of myocardial transverse relaxation time (T2) to quantitate myocardial edema of the right ventricle (RV) and left ventricle (LV) was tested. Dual spin-echo magnetic resonance images of the entire hearts were obtained and T2 of the RV and LV myocardium calculated from the signal intensities within multiple regions of interest distributed over the myocardium. Six hearts were intermittently perfused through an aortic cannula with three perfusates of decreasing osmolality. Biopsies were obtained for water content (WC) analysis both before and after imaging the hearts at baseline and post-perfusion. A seventh (control) heart was not perfused; instead dual spin-echo imaging was performed at the same time intervals as in the perfused hearts. Prior to any intervention, there was no significant difference between baseline RV (79.49 +/- 2.10%) and LV (77.99 +/- 2.44%, p = .2) myocardial water content; RV myocardial T2 (59.9 +/- 5.8 msec) was slightly but not significantly longer than that of the LV (54.6 +/- 5.7 msec, p = .1). After induction of edema, strong correlation was found between right ventricular myocardial water content measurements and right ventricular T2 (RV WC = 68.5 + 0.19 x RV T2; N = 27, R = 0.92, p < .0001, SEE = 1.56%). Similarly, strong correlation was found between left ventricular myocardial water content and T2 (LV WC = 62.1 + 0.29 x LV T2; N = 27, R = 0.92, p < .0001, SEE = 1.80%).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Estimation of right ventricular mass in normal subjects and in patients with primary pulmonary hypertension by nuclear magnetic resonance imaging.
OBJECTIVES: This study was designed to test the accuracy of nuclear magnetic resonance (NMR) imaging as a noninvasive technique for estimating right ventricular mass in normal subjects and in patients with primary pulmonary hypertension. BACKGROUND: An accurate means of noninvasively estimating right ventricular mass may allow better characterization of the degree of right-sided pressure or volume overload caused by underlying cardiac or pulmonary diseases. METHODS: End-diastolic short-axis electrocardiogram (ECG)-gated spin echo NMR images of the heart were obtained in vivo in 13 patients with primary pulmonary hypertension and 10 normal adult volunteers. Both right and left ventricular mass were computed by summing the myocardial slice volumes over all slices spanning the myocardium and multiplying by myocardial density. This technique of myocardial mass determination was verified by imaging 10 calf hearts and comparing the NMR-determined right and left myocardial mass with the actual mass determined by weighing the right and left ventricles. RESULTS: In the calf heart study, an excellent correlation was obtained between the directly measured ventricular mass and the NMR-calculated mass, for both the right and the left ventricle. Patients with primary pulmonary hypertension had an elevated right ventricular mass index compared with that of normal subjects (62.69 +/- 8.72 g/m2 vs. 23.32 +/- 1.36 g/m2, p < 0.0005). There was no significant difference in left ventricular mass index between the two groups. Both mean intraobserver and inter-observer variability in myocardial mass determination were low. Linear regression analysis between right ventricular mass index and mean pulmonary artery pressure was significant (r = 0.75, p < 0.003). CONCLUSIONS: Electrocardiogram-gated spin echo NMR imaging of the heart may be used for quantitating right ventricular mass in normal subjects and in patients with primary pulmonary hypertension, in whom it may also provide an alternative noninvasive technique for estimating mean pulmonary artery pressure.
Adolescent↗
Cholesterol embolization syndrome after intravenous tissue plasminogen activator for acute myocardial infarction.
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Cholesterol↗
Quantitative grading of nerve fiber layer photographs.
PURPOSE: The authors have developed a simple method for semi-quantitative grading of atrophy of the peripapillary nerve fiber layer (NFL) in black and white photographs. METHODS: An experienced observer read sets of NFL photographs using a four-level grading system. Five observers with varying levels of experience at ophthalmic examination were taught the grading system in approximately 4 hours, and their readings were compared with those of the expert. RESULTS: The reproducibility of readings by an experienced observer was excellent. The validity of the grading system was confirmed by comparisons to visual field findings, as well as to cup-to-disc ratios in the same eyes. The agreement with the expert by the five trained graders was good. CONCLUSIONS: Grading of the NFL could be useful both to monitor development of early glaucoma damage clinically and to measure progression of glaucoma damage in clinical trials research. The grading system can be taught readily to other observers.
Adult↗
Use of the carbon dioxide laser to locate small sialoliths.
Six cases of small salivary duct sialoliths were treated using the carbon dioxide laser as a surgical dissector. When the laser beam encountered the small sialolith (3 mm or less), a light-scattering effect (flash or burst) was observed, thus enabling an almost immediate localization of the stone in the salivary duct or in the surrounding tissue. Stone extirpation is more rapid, with less surgical trauma, using this technique.
Adult↗
Clustering of xerophthalmia within households and villages.
The clustering of xerophthalmia within households and villages was estimated among preschool age children using data from studies conducted in Malawi, Zambia, Indonesia and Nepal over the past decade. Pairwise odds ratios (OR) were used to measure the magnitude of clustering. This OR measures the risk of xerophthalmia for a preschool child given that another randomly chosen preschool child from the same household (or same village but different household) had xerophthalmia, relative to the risk if that randomly chosen preschool child did not have xerophthalmia. Village pairwise OR ranged from 1.2 in Malawi to 2.2 in Nepal. Household pairwise OR ranged from 4.4 in Malawi to 9.7 in Indonesia, indicating that xerophthalmia clustering was much greater within households than villages. The magnitude of this clustering was as large, or larger than, infectious outcomes such as diarrhoea, fever and cough. Although xerophthalmia was associated with a weekly history of infectious morbidity, the clustering of diarrhoea, fever and cough explained very little of the xerophthalmia clustering observed in each of these studies, Hence, other household factors such as food availability and dietary practices should be examined for their role in the clustering of xerophthalmia within certain households.
Child, Preschool↗
Comparison of measles virus-specific antibodies with antibody-dependent cellular cytotoxicity and neutralizing functions.
Measles virus-specific antibodies with antibody-dependent cellular cytotoxicity (ADCC) and neutralizing functions were compared in 25 healthy women. ADCC antibody was measured in a 12-h 51Cr release assay using peripheral blood mononuclear cells as effectors and Raji cells persistently infected with measles as targets. Neutralizing antibody was determined by the plaque neutralization test (PNT). ADCC and PNT titers correlated well (r = .80, P < .001). ADCC titers ranged from < 10 to > 10(6) and averaged 1.3 logs higher than PNT titers. Three sera with PNT titers of < 120, including 1 with a titer of < 8 (< 10(0.9)), had ADCC titers of > or = 10(2.5). Among subjects born in the United States, ADCC titers, but not PNT titers, correlated inversely with the year of birth, suggesting that ADCC antibody may be more indicative than neutralizing antibody of differences between naturally and vaccine-acquired immunity. These data suggest a possible role for ADCC in protection or recovery from measles.
Adult↗
Educational needs of nursing quality professionals.
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Education, Nursing, Continuing↗
Magnetic resonance imaging for quantitation of right ventricular volume in patients with pulmonary hypertension.
Evaluation of right ventricular function in patients with right-sided heart failure is difficult because of the complex anatomy of the right ventricle; the distinct geometry of the dilating, failing right ventricle; its variance from the typical oblate spheroid shape used to model the left ventricle; associated cardiac lesions in patients with right ventricular failure (including tricuspid and pulmonary regurgitation); and the inherent risk of conventional contrast ventriculography. With magnetic resonance techniques, tomographic images of the heart may be obtained at multiple points in the cardiac cycle without the use of intravascular contrast agents. From the end-diastolic and end-systolic images, chamber volume may then be determined directly without any modeling assumptions as to the geometry of the ventricular chamber.
Cardiac Volume↗