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Biomedical subjects

J Katz

Publications and source records attributed to J Katz.

At least 487 records · Page 27Linked to original sources
PubMed1988

Lichen planus evoked by periodontal surgery.

A case of Lichen Planus (LP) following periodontal surgery in a patient previously free of the disease is described. Genetic predisposition and lymphokine secretion stimulated by local trauma are suggested as a possible mechanism of the phenomenon. It is recommended that LP patients, especially those suffering from the erosive type, should be treated as conservatively as possible, minimizing the possibility of trauma to the oral tissues where local immunity may have been altered by a pathological process.

Adult↗
PubMed1988

Peripheral T lymphocyte subsets in rapidly progressive periodontitis.

The peripheral blood lymphocyte subsets of 10 patients with rapidly progressive periodontitis were investigated with monoclonal antibody. In 4 patients, the T helper/T suppressor ratio was increased. 5 others had a slightly reduced T helper/T suppressor ratio as compared to control group. These findings may indicate a possible cellular immune response in the pathogenesis of rapidly progressive periodontitis.

Adult↗
PubMed1988

Estimation of human myocardial mass with MR imaging.

The accuracy and reproducibility of magnetic resonance (MR) imaging in the determination of left ventricular mass in humans was investigated. Left ventricular wall volume was measured from ten short-axis, end-diastolic MR images that spanned the left ventricle. Mass was estimated on the basis of average left ventricular wall volume and an assumed myocardial density. To establish the accuracy of the technique, the authors imaged ten cadaver hearts and compared true left ventricular weight with the mass estimate based on MR imaging findings. In vivo determination of left ventricular mass was evaluated in 40 subjects, with resultant calculated masses of 156.4-319.3 g. Intra- and interobserver variabilities of the technique were analyzed in ten subjects. Both the intra- (r = .96, standard error of estimate [SEE] = 11.1 g) and interobserver variabilities (r = .91, SEE = 17.8 g) were excellent. Eight subjects were imaged on two separate occasions to evaluate reproducibility of the technique and confidence limits for a given measurement. For these eight, there was good correlation between the two estimates (r = .93, SEE = 21 g). The authors conclude that MR imaging yields highly accurate and reproducible estimates of left ventricular mass in humans in vivo.

Cadaver↗
PubMed1988

The epidemiology of trachoma in southern Malawi.

A population-based prevalence survey of ocular disease was conducted in the Lower Shire River Valley of Malawi in 1983. A total of 5,436 children less than 6 years of age and 1,664 persons greater than or equal to 6 years were examined. The prevalence of inflammatory trachoma peaked in the 1-2-year-old age group at 48.7% and declined rapidly with age to less than 5% by age 15. The prevalence of cicatricial trachoma was low in young children and climbed gradually with age to greater than 40% among those greater than or equal to 50 years. Risk factors for inflammatory disease in young children included low socioeconomic status of the family, long walking distance to the household's primary source of water, absence of a latrine in the family compound, and presence of trachoma among siblings. Indices of crowding practices were not associated with inflammatory disease. An apparent inverse association of facewashing and inflammatory trachoma in children did not hold up when adjusted for other risk factors.

Adolescent↗
PubMed1988

Two eyes or one? The data analyst's dilemma.

Ophthalmic data usually include measures of disease status, visual function, or ocular physiology for both eyes of each patient. Many ocular characteristics, while differing among individuals, are quite similar for the eyes of the same individual. In studies, eyes, not patients, are often treated as the primary unit of analysis. If an ocular measure is similar for both eyes of an individual, many standard statistical techniques may give misleading results if both eyes of each person are included in analyses. This article discusses the correlation between pairs of eyes for a variety of ocular measures and its impact on common statistical procedures.

Glaucoma↗
PubMed1988

Lithium and memory: a long-term follow-up study.

This study examined the effects of long-term lithium therapy on memory functions in 18 patients suffering from bipolar affective disorder. Patients were retested on the Wechsler Memory Scale, Benton Visual Retention Test, and Zung Self-Rating Depression Scale 6 years after initial testing. Mean memory test scores remained remarkably stable over the 6-year interval with only one of the 10 memory subtests showing a statistically, but not clinically, significant decrease. The sample was split at the median duration of lithium therapy into a long- and shorter term group (with means of 12.9 and 5.2 years, respectively). There were no significant differences between these groups on any of the memory tests when controlled for age and initial memory scores. Negative correlations between several memory test scores and the duration of lithium treatment could in part be explained by the effects of age. Patients' subjective complaints of impaired memory functioning, rated on a visual analogue scale, correlated with the level of depression at the second testing as well as with three memory test scores measuring immediate and short-term visual recall. The results are discussed in view of the demographic and clinical characteristics of the sample and are compared with previous research findings.

Adult↗
PubMed1988

Vascular pressures and passage of gas emboli through the pulmonary circulation.

Anesthetized dogs received venous air infusions at 0.35 ml.kg-1.min-1. In 60% of a group of 15 dogs, venous bubbles spilled over into the arterial circulation and were detected with the ultrasound Doppler technique. The pulmonary vascular pressure gradient (pulmonary artery pressure-pulmonary venous pressure or left atrial pressure) measured at the instant that spillover occurred was 34.7 +/- 4.7 mmHg. In a 2nd group of dogs we raised the pulmonary vascular pressure gradient before the venous air infusions to achieve spillover of bubbles 100% of the time. The resultant pressure gradient at the time of spillover of venous bubbles was 52.0 +/- 2.0 mmHg (P less than 0.05). It is concluded that venous bubbles can cross the lungs of anesthetized dogs when the driving pressures are sufficient to overcome the normal filtering function.

Animals↗
PubMed1987

A longitudinal study of the age-adjusted variability of automated visual fields.

Twenty-six normal eyes of 26 subjects were tested three times during an 18-month period using the 30-2 program of the Humphrey Visual Field Analyzer (Humphrey Instruments, San Leandro, Calif). For the average eye, the SD of threshold values over time ranged from 1.8 to 5.5 dB, depending on the location in the field. For those subjects under 60 years of age, SDs ranged from 1.2 to 2.8 dB. For those subjects 60 years of age and older, the range was 2.2 to 8.3 dB. Short-term fluctuations contributed 25% of the variability of threshold measurements over time. Short-term and long-term variations were greater in older eyes, but long-term variability was more affected by age than was short-term variation.

Adult↗
PubMed1987

The role of ATP in the cytostructure of the hepatocytes.

We have previously described the preparation of hepatocytes from which the plasma membrane was removed by digitonin treatment. Such "nude" cells were found to be very stable in sucrose media containing above 50 mM NaCl or KCl, but they disintegrate near instantly in salt-free media, liberating nuclei, mitochondria, and other organelles. We show here that disintegration occurs at a physiologic pH and in the presence of oxygen. Disintegration was blocked by rotenone, oligomycin, KCN, and carboxyatractyloside, establishing that oxidative phosphorylation and ATP generation is essential for disintegration to occur. The addition of ATP, GTP, ITP, or ADP (but not AMP) in the presence of the inhibitors, induced breakdown. Taxol, an inhibitor of tubulin depolymerization and phalloidin, a drug that stabilizes actin fibers, prevented disintegration in salt-free media. The effect of these drugs was counteracted by the addition of ATP. Our results show that two conditions are essential to induce the disintegration of the nude cell: media of low ionic strength, and ATP generation. The ATP effect is likely to be of physiological significance, suggesting role of ATP generation in affecting polymerization of cytoskeletal elements.

Adenosine Triphosphate↗
PubMed1987

Analysis of spin-echo rephasing with pulsatile flow in 2D FT magnetic resonance imaging.

The effects of pulsatile flow on spin phases in spin-echo magnetic resonance imaging are considered. General expressions for the spin phases of the first four echoes are derived in terms of the Fourier coefficients of flow. These expressions are valid for any time-dependent acceleration and, hence, are not restricted to constant acceleration. The derived expressions are then theoretically evaluated for aortic flow and examined at different points in the cardiac cycle. Our results show that rephasing may occur at certain points in the cardiac cycle for either even or odd echoes depending upon the particular Fourier coefficients of the velocity function and the spin-echo delay time. However, even-echo rephasing is not always necessarily valid. Furthermore, the possibility of determining the flow velocities in the body with an appropriate series of imaging studies is also discussed.

Aorta↗
PubMed1987

Even-echo rephasing and constant velocity flow.

It has been shown previously that for constant magnetic field gradients, constant velocity flow leads to even-echo rephasing for all echo delay times. We show that for flow which is not pluglike, even-echo rephasing also occurs for the pulsed readout gradients used in magnetic resonance imaging if and only if the gradients begin at the time the 90 degrees pulse is applied. We also show for these gradients that even-echo rephasing for all echo delay times in the case of nonpluglike flow implies a constant flow velocity at the point considered. Furthermore, it suffices to assume the vanishing of the spin-echo phase for any even echo, since the vanishing of any even echo for all echo delay times implies that all other even echoes also vanish identically. The odd echoes are then all equal to each other and proportional to the flow velocity. If acceleration is present, it may then be seen that for nonpluglike flow, even-echo rephasing may only be present for some but not all echo delay times. However, for the typical slice selection gradients used in magnetic resonance imaging or for usual readout gradients starting after the 90 degrees pulse is applied, it is shown that for constant velocity flow the even-echo phases do not vanish identically. Hence, rephasing cannot always occur for nonpluglike flow in either of these situations. Furthermore, the spin-echo phases are proportional to the flow velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1987

A general treatment of NMR imaging with chemical shifts and motion.

A general treatment of nuclear magnetic resonance imaging (MRI) and spectroscopic imaging (MRSI), which takes into account the effects of chemical shift, motion, field inhomogeneity, and relaxation times, is presented. A graphical representation based on the k trajectory formalism which includes these effects is then developed for MRI and MRSI acquisition processes. These considerations should be useful in the study and design of flow-sensitive MRI and MRSI methods and the accurate prediction of motion artifacts in conventional MRI and MRSI techniques. We conclude by presenting examples illustrating applications of the general theory to specific MRSI and flow imaging methods.

Fourier Analysis↗
PubMed1987

Desorption of porcine parvovirus from aluminum hydroxide adjuvant with subsequent viral immunoassay or hemagglutination assay.

Cell culture fluids containing porcine parvovirus were adjuvanted with varying concentrations of aluminum hydroxide gel. Adsorption of virus and total protein to adjuvant was proportional to adjuvant concentration. Desorption of virus and protein from the adjuvant in substantial, reproducible quantities was achieved by washing adjuvanted preparations with 1.2 M potassium phosphate, followed by dialysis and concentration of wash fluids. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of unadjuvanted viral fluids, supernatants of adjuvanted mixtures, and desorptive washings of the corresponding adjuvant pellets revealed no qualitative differences in protein banding patterns. Desorbed virus was quantitated by a hemagglutination assay, or by an enzyme-linked immunoassay employing a monoclonal anti-porcine parvovirus antibody. Virus desorption and subsequent assays permitted in vitro estimation of virus content in adjuvanted porcine parvovirus preparations. This approach may be useful in estimating the antigen content of inactivated aluminum hydroxide adjuvanted veterinary vaccines and reducing the extent of required in vivo testing.

Adjuvants, Immunologic↗
PubMed1987

Arterial air embolism of venous origin in dogs: effect of nitrous oxide in combination with halothane and pentobarbitone.

The effects of using nitrous oxide (N2O) with halothane or pentobarbitone anaesthesia on the filtration of venous air emboli (VAE) by the pulmonary circulation were studied in dogs. Dogs anaesthetized with either pentobarbitone, pentobarbitone/N2O, halothane, or halothane/N2O were embolized with venous air into the right atrium at 0.25 to 0.35 ml.kg-1.min-1 for 30 min. The animals were in a supine, head down position. A Doppler ultrasonic probe located over the suprarenal aorta detected arterial bubbles that escaped filtration by the lungs. No bubbles were detected at 0.25 ml.kg-1.min-1, but at 0.30 ml.kg-1.min-1 the incidence was 11 per cent (pentobarbitone), 0 per cent (pentobarbitone/N2O), 33 per cent (halothane), and 63 per cent (halothane/N2O) and at 0.35 ml.kg-1.min-1, 44 per cent (pentobarbitone), 14 per cent (pentobarbitone/N2O), and 56 per cent (halothane). Half of the dogs receiving VAE with halothane/N2O at 0.30 ml.kg-1.min-1 died within the first 10 min of the air infusion. Thus, no animals were studied at the next higher dose (0.35 ml.kg-1.min-1). The results suggest that the occurrence of VAE with nitrous oxide anaesthesia may result in greater haemodynamic consequence and increased likelihood for spillover of the venous bubbles into the arteries if used with halothane as compared to pentobarbitone.

Anesthesia, Inhalation↗