Leptomeningeal metastasis: MR imaging

Seven patients with central nervous system neoplasia and leptomeningeal metastases, proved either at initial diagnosis or on follow-up with contrast material-enhanced computed tomography (CT), were evaluated with magnetic resonance (MR) imaging. In two patients, diffuse sulcal enhancement on CT scans was inapparent on T1- or T2-weighted MR images. Likewise, in four patients diffuse cisternal enhancement on CT scans was not identifiable with MR. Nodular or focal cisternal masses were identified with both CT and MR imaging in three patients; in two, however, MR imaging provided less information. Ependymal and subependymal metastases identified with CT (two patients) were indistinguishable on MR images from periventricular abnormalities of radiation therapy and/or hydrocephalus. These findings suggest that leptomeningeal metastasis may be so subtle or inapparent as to be overlooked with MR imaging alone. Thus, CT and MR imaging should be considered complementary techniques for initial diagnosis and follow-up of tumors with a propensity for leptomeningeal metastasis.     

Fetal lung development: compressibility as a measure of maturity

Fetal lung maturation involves a number of separate developmental processes. An ultrasonic technique is reported for grading the dynamic behavior of the right middle lobe or lingula in the second or third trimesters on ultrasound (US) study. Fetal lungs are stiff initially. Lung compressibility during diastole is typical after 36 weeks' gestational age, when phospholipid profiles of the amniotic fluid also indicate lung-tissue maturity. Compressibility also occurs earlier in the third trimester and has indicated, in preliminary observations on a small subgroup of infants delivered prematurely, a low risk of subsequent neonatal respiratory distress syndrome. High-speed magnification US study of fetal lung compressibility can be used to evaluate fetal lung development, possibly independently of gestational age and of conventionally measured lecithin/sphingomyelin values in amniotic fluid.     

The role of glutathione reductase in maintaining human granulocyte function and sensitivity to exogenous H2O2

Human granulocytes (polymorphonuclear leukocytes, PMN) produce H2O2 and other reactive oxygen species while undergoing phagocytosis. To examine the role of the glutathione cycle in metabolizing H2O2, we incubated PMN with 1,3-bis (2-chloroethyl) nitrosourea (BCNU). Incubation of PMN with BCNU results in a dose-dependent inhibition of PMN glutathione reductase (GRED), with 50% inhibition occurring at approximately 2 micrograms/mL BCNU. PMN hexose monophosphate shunt activity stimulated with an exogenous H2O2-generating system was inhibited only when the GRED activity was reduced to less than 30% of control. BCNU-treated cells contained lower levels of reduced sulfhydryls and reduced glutathione, which decreased even more in the presence of an exogenous H2O2-generating system. The effect of BCNU and exogenous H2O2 on various aspects of phagocytosis were examined. Exposure of BCNU-treated PMN to an H2O2-generating system resulted in an inhibition of chemotactic peptide-induced shape changes and degranulation. The ability of BCNU-treated cells to produce O2- was diminished only when the PMN were incubated with an H2O2-generating system in the presence of cyanide. Ingestion of opsonized bacteria by BCNU-treated PMN was unaffected by incubation in an H2O2-generating system even in the presence of cyanide. We conclude that PMN GRED is inhibited by BCNU, the ability of PMN to metabolize H2O2 is affected only when GRED is reduced more than 70%, this inhibition affects the glutathione content of these cells, and some, but not all of the phagocytic functions of GRED-inhibited PMN are inhibited after exposure to an H2O2-generating system.     

Diverticular disease: imaging with post-double-contrast sigmoid flush

In a prospective study, the effect of infusion of a low-density contrast material was evaluated as an adjunct to high-density, double-contrast imaging of the sigmoid colon. After double-contrast barium enema (DCBE) study, 52 consecutive patients with sigmoid diverticulosis received an additional 500-750-mL enema either with water or a 1.5% barium suspension for computed tomography. Rectosigmoid radiographs were evaluated for luminal distention, visualization of the interhaustral space, definition of diverticula, and interpretation of polypoid defects. While double-contrast views were excellent in 21% of patients, improvement in multiple factors by water or 1.5% barium flush resulted in improved sigmoid images in 65% and 75% of patients, respectively. Polyps were confirmed and artifactual defects confidently excluded. Sigmoid flush, particularly with low-density barium, is a simple adjunct to DCBE study that improves visualization of the diverticular sigmoid and increases interpretive confidence.     

The cubital tunnel in ulnar entrapment neuropathy

Anteroposterior radiographs of the fully flexed and slightly externally rotated elbow were obtained in 122 cases of cubital tunnel syndrome (CUTS) and in 33 normal elbows. Medial trochlear lip osteophytes were not found in the studies of normal elbows but were noted in 20% of ulnar nerve entrapment cases. Medial incongruity between the trochlea and the olecranon greater than or equal to 5 mm was found in 29% of CUTS cases and in 6% of normal elbows. The presence of posttraumatic elbow-joint deformities seen on radiographs correlated significantly with the degree of clinical involvement. Depth and area measurements of ulnar nerve compression, performed using a line-art representation of the radiographs, showed a significant (P less than .0001) correlation between decrease in the area of the cubital tunnel and ulnar innervated muscle atrophy. These findings confirm the importance in this syndrome of both osteoarthritis and incongruity of the medial structures of the elbow joint.     

Cryptosporidiosis of the gastric antrum: detection using CT

We describe a patient who had cryptosporidiosis and cytomegalovirus infection of the gastric antrum that was initially detected on computed tomography (CT) scans. CT may be useful in the evaluation of immunocompromised patients with diarrheal illness, as well as in the assessment of the gastrointestinal tract.     

Activation of neutrophil superoxide production by concanavalin A can occur at low levels of intracellular ionized calcium

The effect of concanavalin A (Con A) on the concentration of ionized intracellular calcium [( Cai++]) in human granulocytes (PMN) was monitored using the fluorescent calcium indicator and chelator, Quin2. The addition of Con A to PMN resulted in a rise in [Cai++] that was markedly enhanced by the presence of Ca++ in the external buffer. The onset of the increment in [Cai++] preceded the onset of O2- production. The rise in [Cai++] induced by Con A is not transient, with a new, higher steady-state level of [Cai++] being attained within five minutes. The addition of alpha-methylmannoside (alpha-MM) one minute after Con A resulted in the return of [Cai++] to the original baseline level and the cessation of O2- production. The addition of a second stimulus (such as arachidonic acid) to these cells resulted in a second increment in [Cai++] and the return of O2- production. Thus the rise in [Cai++] induced by Con A is tightly coupled to the activation, inactivation, and reactivation of the O2- generating system by Con A. Further experiments were undertaken to assess the possible requirement for the rise in [Cai++] in the activation of PMN by Con A. PMN could be depleted of Cai++ by loading with Quin2 in the absence of extracellular Ca++. These Ca++- depleted PMN can be induced to produce O2- after treatment with PMA but not with Con A. The addition of Ca++ to Ca++ - depleted PMN results in a return of [Cai++] to the normal resting level of Ca++ -replete PMN. The time required to return to baseline is a function of the concentration of intracellular Quin2. The addition of Ca++ to Ca++ -depleted, Con A-treated PMN results in the elevation of [Cai++] and the production of O2-. Over a tenfold range of intracellular Quin2 concentration, the onset of O2- production always occurred at [Cai++] that were less than the normal resting level. Thus, activation of the O2- generating system by Con A can occur at [Cai++] which are much lower than the incremental level induced by Con A in Ca++ -replete PMN. Supporting this is the observation that only a very small increment in [Cai++] is induced by Con A in PMN cytoplasts, even though Con A could induce O2- production in the Quin2-loaded cytoplasts.(ABSTRACT TRUNCATED AT 400 WORDS)