Can we justify not doing liver perfusion imaging in 2013?

Liver perfusion imaging is a quantitative functional investigation. Liver perfusion imaging is complicated because of the liver's dual vascular supply, artefacts due to respiratory movements and the fenestrated sinusoidal capillaries which allow the contrast medium to diffuse out. Liver perfusion can be examined by ultrasound, CT or MRI: each technique has its limitations and specific features. The major indications in hepatology are oncology (detection, characterization and tumor response) and non-invasive investigation of patients with chronic liver disease. Work is needed to standardize acquisition and modeling methods to allow wider use of results and more widespread use of the technique.

Magnetic resonance spectroscopy for evaluation of liposome-encapsulated hemoglobin as a resuscitation fluid.

Liposome-encapsulated hemoglobin (LEH) based on a novel, synthetic, non-phospholipid was developed, and evaluated for cerebral energy metabolism in a 40% hemorrhage rat model. The markers of tissue energetics were monitored by (1)H- and (31)P-magnetic resonance spectroscopy (MRS). After hemorrhage, (1)H-MRS showed an increase in the levels of lactate and pyruvate. These markers returned to baseline values following LEH resuscitation. Both LEH and saline were able to exert a neuron-protective effect as indicated by the recovery of N-acetylaspartate. (31)P MRS showed a fall in phosphocreatine after hemorrhage, which upon LEH or saline resuscitation returned to the baseline values. Similarly, inorganic phosphate increased after bleeding, but returned to normal after resuscitation. LEH resuscitation also recovered beta-ATP levels, but saline resuscitation provided only a modest recovery. The results indicate the utility of MRS to monitor cerebral metabolism in hemorrhage/resuscitation. The data is also supportive of the new LEH formulation as an oxygen carrier.

Basal and hypercapnia-altered cerebrovascular perfusion predict mild cognitive impairment in aging rodents.

With increasing age, a subset of otherwise healthy individuals undergoes impairments in learning and memory that have been termed mild cognitive impairment (MCI). The enhanced neuronal activity associated with learning and memory requires increased cerebral blood flow (CBF) to specific brain regions. However, the interactions between cerebral blood flow and MCI remain unclear. In this study, we address whether baseline or hypercapnia-induced (increased blood CO(2) levels) changes in CBF are modified with age, and whether these measures are predictive of cognitive status in rodents. Adult and aged rats were evaluated using a hippocampally-dependent task in a water maze. Aged rats were classified as memory-impaired or memory-intact based on performance comparisons with adult rats. Cerebral blood flow was assessed using flow-alternating inversion recovery (FAIR) magnetic resonance imaging (MRI), before and after breathing 10% CO(2). The transition period between CO(2) concentrations was examined with blood oxygen level dependent (BOLD) MRI. Separation of aged animals into memory-intact and impaired categories revealed increased basal perfusion in the dorsal hippocampus of memory-impaired versus memory-intact aged animals. Linear regression revealed that higher hippocampal perfusion was correlated with impaired memory in aged animals, and a logistic regression indicated that hippocampal perfusion predicted spatial memory ability. Several brain regions of aged rats demonstrated an attenuation of the perfusion increase normally observed in adult rats under hypercapnia. Memory-impaired animals were the primary contributor to this effect, as their perfusion response to hypercapnia was significantly reduced compared to adult animals. Aged, memory-intact animals were not significantly different from adults. BOLD MRI demonstrated a reduced response in aged animals to hypercapnia, with impaired animals being the primary contributor to the effect. A logistic regression model based on basal and hypercapnia perfusion correctly predicted cognitive status in 83.3% of animals tested. Our results indicate that age-related changes in vascular reactivity and perfusion are important contributing factors in memory impairment.

In vivo detection of c-Met expression in a rat C6 glioma model.

The tyrosine kinase receptor, c-Met, and its substrate, the hepatocyte growth factor (HGF), are implicated in the malignant progression of glioblastomas. In vivo detection of c-Met expression may be helpful in the diagnosis of malignant tumours. The C6 rat glioma model is a widely used intracranial brain tumour model used to study gliomas experimentally. We used a magnetic resonance imaging (MRI) molecular targeting agent to specifically tag the cell surface receptor, c-Met, with an anti-c-Met antibody (Ab) linked to biotinylated Gd (gadolinium)-DTPA (diethylene triamine penta acetic acid)-albumin in rat gliomas to detect overexpression of this antigen in vivo. The anti-c-Met probe (anti-c-Met-Gd-DTPA-albumin) was administered intravenously, and as determined by an increase in MRI signal intensity and a corresponding decrease in regional T(1) relaxation values, this probe was found to detect increased expression of c-Met protein levels in C6 gliomas. In addition, specificity for the binding of the anti-c-Met contrast agent was determined by using fluorescence microscopic imaging of the biotinylated portion of the targeting agent within neoplastic and 'normal'brain tissues following in vivo administration of the anti-c-Met probe. Controls with no Ab or with a normal rat IgG attached to the contrast agent component indicated no non-specific binding to glioma tissue. This is the first successful visualization of in vivo overexpression of c-Met in gliomas.

[Scientific investigation in biomedicine and health sciences in Andalusia]. / La investigación científica en Biomedicina y Ciencias de la Salud en Andalucía.

OBJECTIVES: To evaluate the scientific output in Biomedicine and Health Sciences in Andalusia in the context of the published works on the national scientific output in the last few years. MATERIAL: Descriptive study with seven different information sources: a) final Report of the Experts Committee on Documentation from the Consejería de Salud de la Junta de Andalucía (IME: Indice Médico Español) suplemento internacional: 1980-1994; b) MEDLINE (Comprehensive Medline Ebsco, 1987-1993); c) EMBASE (Excerpta Medica; Elsevier Science Publisher) (1986-1994); d) IME, mechanized version: 1974-1993; Anales del FIS (1989-1993); e) Memoria REUNI: 1993-1994, and f) call for and resolution of research projects from the Consejería de Salud de la Junta de Andalucía (1994). RESULTS AND CONCLUSIONS: Scientific output in health sciences in Andalusia has gown in parallel with the national output from other communities. Nevertheless, in absolute terms this output is scant and the big difference compared with Catalonia and Madrid--the two Autonomous Communities with the largest scientific output--remains unchanged. Grenada is the Andalusian province with the largest output, with Seville, Cordoba and Malaga ranking next. The output in the other Andalusian provinces is very small. The output is apparently independent from the number of inhabitants or the historic presence of a Medicine School. In contrast with Catalonia and Madrid, where the largest output originates in hospitals, the largest output in Andalusia comes from Universities; this fact suggests relevant differences in scientific sub-structure. This suggestion is also endorsed by the lower competition of Andalusia to obtain resources and the lower number of research scholarships. With these results in mind a scientific policy of positive discrimination is proposed which allows the Andalusian Autonomous Community to reach the standard of scientific output in biomedicine and health sciences according to its socioeconomic status.