Three-dimensional MDCT angiography for the assessment of arteriovenous grafts and fistulas in hemodialysis access.

Arteriovenous grafts and fistulas are placed for long-term hemodialysis access, and their associated complications can lead to considerable morbidity. Multi-detector computed tomography (MDCT) images provide accurate delineation of hemodialysis access anatomy and show potential complications. This review makes the reader more familiar with vascular access anatomy and configurations, describes the appearance of access complications encountered on MDCT, and discusses endovascular and surgical treatment options for complications, which should aid in post-treatment evaluation.

Unusual radiographic appearance of drug-induced pharyngeal angioedema and differential considerations.

A 59-year-old woman treated chronically with enalapril, an angiotensin-converting enzyme inhibitor (ACE-I) presented with difficult swallowing and speaking. Although her symptoms were clinically consistent with an adverse angioedema reaction to the ACE-I, initial imaging was not entirely consistent with our conceptual understanding of angioedema. This case report will discuss the myriad possible imaging presentations of this disease, as well as the differential diagnosis for this atypical manifestation of ACE-I-induced angioedema.

Neural substrates of word generation during stroke recovery: the influence of cortical hypoperfusion.

Several studies have demonstrated reorganization of cognitive and motor function caused by stroke. This study examined the influence of hypoperfused brain regions, in addition to the area of the infarct itself, on reorganization of the cognitive processes underlying word generation in stroke patients. In addition, we also sought to determine the influence of hypoperfusion on the blood oxygen level dependent/(BOLD) effect. Subjects with left and right subacute or chronic subcortical strokes, along with normal controls, were imaged while performing a verbal fluency task (word generation). The study population included six normal subject and six stroke patients with subcortical infarcts and cortical hypoperfusion in the middle cerebral artery territory who had recovered or improved markedly in word fluency. While normal subjects displayed a left-lateralized fronto-temporo-parietal and bilateral cingulo-striatal-thalamic-cerebellar network, the activation pattern of stroke patients was determined both by the hypoperfused regions and infarcted areas of the brain. Specifically, patients showed diminished BOLD effect in the cortical regions that were hypoperfused, even though their infarcts were subcortical, and showed increased BOLD effect in the homologous regions of the normal hemisphere. This finding raises the possibility that cortical hypoperfusion in the absence of infarct can cause shift of language functions to the opposite, intact hemisphere. However, reduced BOLD effect in the task relative to rest was found in hypoperfused regions in two patients, raising the possibility that regional function persisted, even though vascular reactivity was impaired. Results illustrate the complexities of functional imaging studies of recovery in patients with vascular lesions.

Antiretroviral use and other risks for HIV-associated neuropathies in an international cohort.

OBJECTIVE: To explore the association between specific nucleoside reverse transcriptase inhibitors and sensory neuropathies (SNs) and define the modifying roles of hepatitis C (HCV), vitamin B12 deficiency, and impaired glucose tolerance. METHODS: The authors conducted a prospective cohort study of 147 HIV-infected adults at two sites chosen to emphasize demographic differences. Standardized assessments included detailed antiretroviral histories, neurologic examinations, skin biopsies for epidermal nerve quantitation, and quantitative sensory testing. RESULTS: There were significant differences between subjects at Johns Hopkins University (JHU) and Monash University (MU) in gender, race, HIV transmission route, and HCV seroprevalence. Symptomatic SN was present in 49% at JHU and 55% at MU (chi2 = 4.02, p = 0.134) and was significantly more common in those at least age 40 than younger patients (odds ratio [OR] = 2.87, 95% CI = 1.27, 6.49). After adjusting for site, age, and CD4 cell count, exposure to didanosine (ddI) or stavudine (d4T) was associated with an significantly increased likelihood of symptomatic SN (ddI: OR = 3.21, 95% CI: 1.56, 6.60; d4T: OR = 7.66, 95% CI: 2.89, 20.33). Plasma HIV RNA, lactate, and HCV were not associated with SN. Quantitative vibratory testing identified neuropathy with a positive predictive value of 76% and epidermal nerve fiber densities 59%. CONCLUSIONS: Exposure to stavudine and didanosine was significantly associated with a heightened risk for symptomatic sensory neuropathy. Reduced vibration thresholds and epidermal nerve fiber densities had the highest diagnostic efficiency of the laboratory indicators of neuropathy examined, but were relatively insensitive in isolation.

Altering creatine kinase isoenzymes in transgenic mouse muscle by overexpression of the B subunit.

To change the levels of expression and isoenzyme distribution of creatine kinase (CK) in muscle, transgenic technology was used to express the B subunit of CK in mouse muscle. Normally, mammalian skeletal muscle contains the MM dimer of CK. The BB dimer and MB heterodimer of CK can be found in brain and heart, respectively. Heterologous genes consisting of skeletal and cardiac muscle-specific actin promoters fused to the genomic coding region of the B form of CK were used to create transgenic mice. Lines were established from the three highest expressing founders. Analysis of skeletal muscle extracts revealed that all three lines had an increase in total CK activity measured under maximal velocity conditions. The highest expressing line, 7001, had a CK activity 150% that of control muscle. Nuclear magnetic resonance saturation transfer was used to measure the in vivo rate of the CK reaction. In 7001 hindlimb muscles, the CK catalyzed reaction was 200% that of control muscle. The elevation in CK activity in transgenic muscle was accompanied by significant changes in the composition of the cytosolic isoenzyme ratio of CK. In control, 100% of CK was MM, whereas 7001 had 60 +/- 18% MM, 32 +/- 10% MB, and 8 +/- 2% BB. There were no changes in ATP, phosphocreatine, Pi, or creatine levels in transgenic muscle compared with control. Immunofluorescence of myofibrils isolated from control and transgenic muscle revealed specific association of CK to the M line. Small amounts of MB CK were detected on myofibrils from transgenic mice. Transgenic mice expressing the B subunit of CK in muscle represent a first step toward altering CK isoforms so as to elucidate the specific roles of these isoforms in energy metabolism.