Dynamic imaging with lanthanide chelates in normal brain: contrast due to magnetic susceptibility effects

Using a one-dimensional rapid imaging technique, we have found that injection of lanthanide chelates such as Gd(DTPA)2- leads to a significant decrease (50%) in rat brain signal intensity at 1.45 T using T2-weighted pulse sequences; however, no effect of comparable size is observed with T1-weighted pulse sequences. The transient effect and its kinetics were followed with a temporal resolution of between 1 and 8 s. Experiments with different lanthanide chelates show that the observed decrease in signal intensity correlates with the magnetic moment of each agent but not with their longitudinal relaxivity. Three-dimensional chemical-shift resolved experiments demonstrate significant line broadening in brain during infusion with Dy(DTPA)2-. Our results show that the cause of this effect is the difference in susceptibility between the capillaries, containing the contrast agent, and the surrounding tissue. As a result of these susceptibility differences, field gradients are produced in the tissue and diffusion of water through these gradients leads to a loss of spin phase coherence and thus a decrease in signal intensity. We propose this as a new type of contrast agent mechanism in NMR. The effect and its kinetics are likely to be related to important physiological parameters such as cerebral blood volume and cerebral blood flow, and do not depend on a breakdown of the blood-brain barrier as do conventional contrast agent techniques.     

Effects of cocaine and quinpirole on perceptual and motor functions in baboons

 The effects of cocaine and quinpirole were studied in baboons to determine whether quinpirole, a relatively selective D₂/D₃ dopamine agonist, produced effects similar to those of cocaine on perceptual and motor processes. To measure perceptual and motor function, three baboons were trained to discriminate differences between a standard vowel and four other synthetic vowels; response accuracy as well as response latencies, or ”reaction times”, were measured following drug administrations. Cocaine reduced reaction times in two baboons, and did not affect reaction times in a third; on the other hand, quinpirole lengthened reaction times in a dose-dependent manner in all baboons. Cocaine and quinpirole also differed in the time course to produce the maximal reaction time effect following drug administration. Cocaine and quinpirole did not differ consistently in their perceptual effects, as indicated by similar changes in d′, a signal-detection index of discriminability. These distinct profiles of effects for cocaine and quinpirole suggest differing neurochemical actions for these two drugs. Received: 10 August 1996 /Final version: 16 May 1997     

Congenital absence of extraocular muscles: MR demonstration.

We describe a case of an infant with complete congenital absence of the extraocular muscles, noted at surgery and confirmed by multiplane MR, which found no evidence of extraocular muscle tissue. This almost certainly represents an extreme form of bilateral congenital fibrosis syndrome.     

INTRA-AORTIC BALLOON RUPTURE CAUSING FEMORAL ENTRAPMENT

Rupture of an intra-aortic balloon counterpulsator (IABCP) demands immediate removal. We report a case of thrombus formation within a Datascope IABCP secondary to IABCP rupture, necessitating surgical exploration for removal. There is a disturbing pattern of balloon ruptures with this type of IABCP.     

Ciprofloxacin-induced renal insufficiency in cystic fibrosis.

Acute renal insufficiency is known to occur in patients who are taking ciprofloxacin, particularly the elderly. We report two young patients with cystic fibrosis who presented with acute renal insufficiency after 2-3 weeks of oral ciprofloxacin therapy. The incidence of this adverse effect in children and young adults who have cystic fibrosis is unknown. Multiple mechanisms for ciprofloxacin-induced nephrotoxicity have been proposed.     

Becoming a mother — an analysis of women's experience of early motherhood

This paper presents the results of a qualitative study conducted by midwife researchers into women's experience of new motherhood. Data were collected using focus groups involving 55 first-time mothers and analysed using grounded theory method. The analysis produced six categories: 'realizing', 'unready', 'drained', 'aloneness', 'loss' and 'working it out'. The core category, 'becoming a mother', integrates all other categories and encapsulates the process of change experienced by women. Also explained are factors mediating the often distressing experience of becoming a mother. The analysis provides a conceptualization of early motherhood enabling the development of strategies for midwives, nurses and others helping women negotiate this challenge.     

Recurrence of posterior uveal melanoma after 60Co episcleral plaque therapy

The authors analyzed the clinical and follow-up data on 277 selected patients with primary choroidal or ciliochoroidal melanoma who were treated with 60Co plaque radiotherapy between 1976 and 1982. Local recurrence of the irradiated melanoma developed in 39 (14%) patients during the follow-up interval. The 5-year tumor recurrence rate (Kaplan-Meier) was estimated to be 12%. Multivariate prognostic factor analysis (Cox proportional hazards modeling) identified the largest linear tumor dimension and proximity of the posterior margin of the tumor to the optic nerve head as predictors of recurrence. The 5-year survival rate of patients whose tumors recurred (58%) was significantly (log-rank test P = 0.0023) worse than that of patients whose tumor remained clinically controlled (82%).     

The association of alcoholism and anxiety

The relationship between alcoholism and anxiety disorders is complex and has been the subject of much investigation. While data from community samples as well as samples of treatment-seeking populations indicate that these disorders co-occur far more commonly than would be expected by chance, the nature of the relationship is unclear. It is clear from both prevalence as well as order of onset data that various anxiety disorders have differing associations with alcohol problems. There is much overlap in symptomatology of panic disorder, generalized anxiety disorder, and alcohol withdrawal. This observation has led to speculation about common neurochemical perturbations and a kindling phenomenon as a possible connection between these disorders. Cognitive theories have been used to connect alcohol abuse and phobic disorders. Treatment of patients with co-morbid anxiety and alcoholism is discussed.