Maintenance of myelinated fibre g ratio in acute experimental allergic encephalomyelitis

The spectra of myelin sheath thickness and g ratio (axon diameter/fibre diameter) of guinea pig optic nerves for 8 animals with acute experimental allergic encephalomyelitis (EAE) were compared with those for 6 normal animals. The mean myelin sheath thickness of 0.12 microns for the animals with EAE was significantly lower than the value of 0.16 microns for the normal animals. Since fibre diameter comprises axon diameter plus the thickness of its surrounding myelin sheath, a reduction in mean fibre diameter from 1.52 microns in normals to 1.20 microns in EAE was expected, but it was surprising to find that a mean g ratio of 0.85 obtained for normal nerves was not substantially different from a value of 0.86 for demyelinated optic nerves. A decrease in the mean axon diameter of 1.24 microns for normal animals to 0.94 microns for those with EAE tended to offset the decrease in mean myelin sheath thickness and contributed to the relative stability of the g ratio with acute demyelination. Our results showing reduction in axonal calibre and myelin sheath thickness may offer an explanation for apparent discrepancies between electrophysiological delays in conduction characteristics of experimental and, if not the result of a maturational effect on myelination, human primary demyelinating disorders associated with the scant histopathological demyelination of initial attacks of EAE and the visually asymptomatic patients with multiple sclerosis.

Disturbed body image in patients with eating disorders

OBJECTIVE

The authors attempt to answer the question of whether patients with eating disorders experience more distortions in body image than do individuals without eating disorders.

METHOD

The study group was composed of 214 women out of 230 patients consecutively admitted to an inpatient eating disorders program. Twelve men and four patients with atypical eating disorders were excluded from study. The 214 patients were divided into three groups: 87 with anorexia nervosa alone, 72 with anorexia and bulimia nervosa, and 55 with bulimia nervosa alone. The comparison group was composed of 61 women drawn from 125 consecutive participants in a survey of university students. Fifty-six men were dropped from the comparison group, along with eight women who fulfilled diagnostic criteria for eating disorders. Each subject used a three-dimensional measure to rate her body size and stated her desired body size at seven points: left biceps, left calf, left thigh, waist, abdomen, hips, and bust. The subjects' measurements at each of these points were taken. Distortion in body image was calculated as the subject's perceived body size divided by her actual body size. All subjects were also given a battery of tests of intelligence, skill, and memory.

RESULTS

All three patient groups differed significantly from the comparison group in distortions in body image. Most but not all patients with eating disorders had distortions in their body image.

CONCLUSIONS

If replicated, these findings would suggest that the diagnostic criteria regarding disturbance of body image for both anorexia and bulimia need to be revised.

Synergistic inhibition by verapamil and quinine of P-glycoprotein-mediated multidrug resistance in a human myeloma cell line model

In an effort to develop a clinically useful approach to overcoming P-glycoprotein-mediated multidrug resistance (MDR1), we evaluated combined chemosensitization with verapamil and quinine in a multidrug-resistant (MDR) human myeloma cell line model. In clonogenic assay, verapamil was used at concentrations from 0.1 to 1.0 micrograms/mL, bracketing the plasma levels achieved by oral administration and high-dose intravenous (IV) infusion, respectively. The dose of quinine was held constant at 1.0 micrograms/mL, a plasma concentration readily achieved by oral administration. At each dose level of verapamil tested, the combination with quinine proved more effective than either drug individually in reversing resistance to doxorubicin and vinblastine and synergistic chemosensitizing interaction was observed. Verapamil at 0.1 microgram/mL combined with quinine was capable of restoring sensitivity to doxorubicin fully and reduced resistance to vinblastine as effectively as verapamil alone at 1.0 micrograms/mL. Furthermore, the combination of 1.0 mumol verapamil with 10 mumols quinine increased accumulation and retention of anthracycline in the resistant cells to a greater extent than did either drug individually (P less than .001) and inhibited drug efflux as effectively as verapamil alone at 10 mumols. Our findings suggest that combined chemosensitization with verapamil and quinine may prove useful for overcoming MDR1 in patients with drug-refractory B-cell neoplasms such as multiple myeloma or non-Hodgkin's lymphomas.

Increased neutrophil elastase release in unstable angina pectoris and acute myocardial infarction

Neutrophils, a source of proteolytic enzymes and oxygen free radicals, have been shown to participate in animal models of myocardial ischemic injury. To characterize neutrophil activation in human ischemic heart disease, a specific neutrophil elastase-derived fibrinopeptide in plasma was measured in 25 patients with stable angina pectoris, 29 patients with unstable angina pectoris, 17 patients with acute myocardial infarction and 22 control subjects. Mean plasma levels (+/- standard error) of a neutrophil elastase-derived fibrinopeptide (B beta 30-43) measured by a specific radioimmunoassay were fivefold higher in patients with acute myocardial infarction (877 +/- 337 pmol/liter, p less than 0.02) and 13-fold higher in patients with unstable angina (2,277 +/- 613 pmol/liter, p less than 0.006) as compared with control subjects (172 +/- 74 pmol/liter). Mean plasma levels of peptide B beta 30-43 in patients with stable angina (676 +/- 334 pmol/liter), although higher than in control subjects, were not significantly increased (p = 0.64). Total leukocyte counts were 11.0 +/- 0.6 x 10(6)/ml in those with acute myocardial infarction, 9.2 +/- 0.7 x 10(6)/ml in those with unstable angina, 7.1 +/- 0.3 x 10(6)/ml in those with stable angina and 7.7 +/- 0.4 x 10(6)/ml in control subjects. Although total leukocyte counts in patients with unstable angina pectoris and acute myocardial infarction were higher (p less than 0.01) than in patients with stable angina or in control subjects, elevations in peptide B beta 30-43 levels were independent of the differences in both leukocyte count and absolute neutrophil count as well as in history of smoking, hypertension, diabetes mellitus or treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Research resources in academic radiology

Research resources in academic radiology were investigated by analyzing the responses to a survey from 72 North American institutions. The questionnaire addressed five general areas: department size, departmental resources committed to research, availability of research training, research quality control, and research productivity. The highest correlates of grant productivity included measures of departmental resources committed to research, for example, space devoted to research, size of research budget, and full-time employee support for engineers, physicists, and chemists. In a regression model, measures of the number of engineers employed by a department, the number of attending staff, and the number of training lectures given by engineers were found to be most highly associated with dollar value of grant support. The average level of research resources available at responding institutions was generally low, despite a seemingly strong desire to do quality research. This is evidenced by a strong sentiment among respondents in favor of research training and quality control of research.

Effects on overviews of early stopping rules for clinical trials

Use of inappropriate stopping rules for clinical trials results in an excess of false positive conclusions when no true survival differences exist. Overviews of such trials, however, consist mainly of trials which were not stopped early, plus a few of reduced sample size which were. Simulations confirm that the level of such an overview is minimally elevated. Additional follow-up for survival further corrects the level. In fact, for individual trials conducted according to inappropriate rules, late tests have nearly correct level. On the other hand, publication bias (differential reporting of positive results) can substantially increase the level of an overview if only published studies are included.

Functional assessment of T cell depletion from bone marrow prior to therapeutic transplantation using limiting dilution culture methods

We evaluate the usefulness of limiting dilution culture methods in assessing the extent of T lymphocyte depletion from bone marrow inocula, prior to transplant, using either ex vivo antibody/complement-mediated depletion or immunotoxin treatment. Complement-mediated depletion using anti-Leu-1 antibody was shown to result in a consistent decline of 99%-99.9% in the frequencies of T cells able to proliferate in mitogen-stimulated, interleukin-2 (IL-2)-supplemented cultures. Equivalent declines were demonstrated in frequencies of "helper" T cells able to respond to mitogen by making IL-2, and in "killer" T cells able to give rise to clones of cytotoxic effectors. In most experiments, a second cycle of anti-Leu-1 + complement treatment did not further diminish the fraction of proliferating cells, although T cells able to secrete IL-2 were additionally depleted following a second cycle of antibody and complement. The limiting dilution methods were found to be at least as sensitive as flow cytometric (FACS) methods for detecting residual T cell contamination after protocols involving complement-mediated lysis, and superior to FACS analysis for protocols involving T cell depletion by a ricin A chain-anti-T101 immunotoxin, in which treated T cells suffer functional impairment and eventual death after exposure to immunotoxin, but remain phenotypically detectable during FACS analysis. Although limiting dilution methods do not provide data as rapidly as FACS analyses, they do not require a cytofluorimeter, provide equal or greater sensitivity, and can assess functional impairment, for both helper and killer T cell sets, even in situations in which the depletion procedure does not lead to immediate cytolysis.

Effect of Oxygen Tension, Mn(II) Concentration, and Temperature on the Microbially Catalyzed Mn(II) Oxidation Rate in a Marine Fjord

We present evidence that the oxidation of Mn(II) in a zone above the O 2 /H 2 S interface in the water column of Saanich Inlet, British Columbia, Canada, is microbially catalyzed. We measured the uptake of 54 Mn(II) in water samples under in situ conditions of pH and temperature and in the presence and absence of oxygen. Experiments in the absence of oxygen provided a measure of the exchange of the tracer between the dissolved and solid pools of Mn(II); we interpret the difference between experiments in the presence and absence of oxygen to be a measure of Mn(II) oxidation. Using this method we examined the effect of oxygen tension, Mn(II) concentration, and temperature on the initial in situ Mn(II) oxidation rate ( V 0 ). Mn(II) oxidation was almost twice as fast under conditions of 67% air saturation ( V 0 =5.5 nM h −1 ) as with the in situ concentration of 15 μM (5% air saturation; V 0 =3.1 nM h −1 ). Additions of ca. 18 μM Mn(II) completely inhibited all Mn(II) oxidation at three different depths in the oxidizing zone, and there was a temperature optimum for Mn(II) oxidation of around 20°C. These results are consistent with biologically mediated Mn(II) oxidation and indicate that the rate is limited by both oxygen and the concentration of microbial binding sites in this environment.

COPE: a systematic approach to moving chronic patients into the community

COPE, a program designed to help chronic psychiatric patients make the transition from institutionalization to independent living in the community, emphasizes both in-hospital training the systematic aftercare as two points on a continuum of treatment. The program includes four training phases, with each phase based upon the skills acquired in the preceding one. The residents are thereby assured of having the necessary skills for progressing to more complex tasks as they proceed through the program. During the last phase, support by the mental health system is gradually replaced by help from community support systems.

Distribution and Uptake of Artificially Introduced Radium-226 in a Small Lake

Radium-226 was added to lake 227 of the Experimental Lakes Area in August 1970 so that gas-exchange rates between the atmosphere and the lake could be traced by its gaseous daughter product radon-222. Although we expected the radium to remain in solution it did so for only about 1 month. An investigation to locate the radium after it left solution revealed that it was taken up on the bottom in the littoral zone. Further experiments indicated that it had adsorbed to the algal detrital material on the littoral sediment surface. Seasonal movement of this material could thus be monitored by following the movement of the radium with time.

Atmospheric carbon dioxide: its role in maintaining phytoplankton standing crops

The rate of invasion of carbon dioxide into an artificially eutrophic Canadian Shield lake with insufficient internal sources of carbon was determined by two methods: measuring the carbon : nitrogen : phosphorus ratios of seston after weekly additions of nitrogen and phosphorus, and measuring the loss of radon-222 tracer from the epilimnion. Both methods gave an invasion rate of about 0.2 gram of carbon per square meter per day. The results demonstrate that invasion of atmospheric carbon dioxide may be sufficient to permit eutrophication of any body of water receiving an adequate supply of phosphorus and nitrogen.