The effects of dietary saturated fat source on weight gain and adiposity are influenced by both sex and total dietary lipid intake in zebrafish

The effects of saturated fat intake on obesity and cardiovascular health remain inconclusive, likely due in part to their varied nature and interactions with other nutrients. Investigating the synergistic effects of different saturated fat sources with other dietary lipid components will help establish more accurate nutritional guidelines for dietary fat intake. Over the past two decades, zebrafish (Danio rerio) have been established as an attractive model system to address questions regarding contributions of dietary lipid intake to diet-induced obesity in humans. The goal of the present study was to assess interactions of three different saturated fat sources (milk fat, palm oil, and coconut oil) with sex and total dietary lipid intake on weight gain and body composition in adult zebrafish. Larvae were raised on live feeds until 28 days post fertilization, and then fed a formulated maintenance diet until three months of age. An eight-week feeding trial was then initiated, in which zebrafish were fed nine experimental low- and high-fat diets varying in saturated fatty acid and long-chain polyunsaturated fatty acid content, in addition to a low-fat and high-fat control diet. At termination of the feeding trial, each treatment was evaluated according to body mass, moisture content, and adiposity. Sex and diet significantly interacted in their effects on body mass (P = 0.026), moisture content (P = 0.044), and adiposity (P = 0.035). The influence of saturated fat source on body mass was observed to be dependent on intake of total dietary lipid. In females, all three saturated fat sources had similar effects on adiposity. From these observations, we hypothesize that impacts of saturated fat intake on energy allocation and obesity-related phenotypes are influenced by both sex and intake of other dietary lipid components. Our results suggest that current nutritional guidelines for saturated fat intake may need to be re-evaluated and take sex-specific recommendations into consideration.

Pituitary microcirculation: physiological aspects and clinical implications. A laser-Doppler flow study during transsphenoidal adenomectomy

The anterior and posterior pituitary lobes (AL and PL, respectively) are assumed to differ in the type of vascular supply and structure of their microvascular networks. Animal experiments have shown that the pituitary microvascular flow differs between the two lobes, being extremely high in the PL and low in the AL. For technical reasons, it has hitherto not been possible to study pituitary microflow in humans. Laser-Doppler flowmetry (LDF) is now a well-established method for real-time monitoring of microcirculation, applicable also in humans. In a prospective clinical study, the microflow in the AL and PL was measured during transsphenoidal microsurgery in 52 patients with adenomas of different size, growth characteristics, and endocrinological activity. The mean microflow in the PL (177.7 +/- 12.6 [flux]) was found to be about six times higher than that in the AL (27.4 +/- 2.7 [flux]). No difference in the laser-Doppler fractional volume of the lobes could be detected (0.73 +/- 0.06 [] vs. 0.77 +/- 0.07 [], where [] designates the ratio of the alternating current output to the direct current output signals). Microflow within the pituitary lobes was influenced neither by the histological type nor the size of the adenoma. Additionally, LDF signal-averaging triggered by the electrocardiogram allowed detection of different characteristic pulsatile microvascular flow patterns in the AL and PL. Our findings provide strong physiological support for the idea that the angioarchitecture of the pituitary lobes differs. With this method, the AL and PL can be identified objectively during surgery. LDF might provide useful information concerning intraoperative surgical approach.

Hyperperfusion syndrome after carotid endarterectomy: a transcranial Doppler evaluation

Transcranial Doppler ultrasonography was used to evaluate 2 patients who developed hyperperfusion syndromes after carotid endarterectomy. During the initial postoperative period, each patient had symptoms that were associated with elevated flow velocities in the ipsilateral cerebral vasculature. In addition, vascular resistance of these vessels was found to be abnormally low, as reflected by the Gosling pulsatility index. As the patients' symptoms improved, flow velocities decreased to normal levels and pulsatilities were noted to increase proportionately.

Transcranial Doppler monitoring of cerebral flow velocities during surgical occlusion of the carotid artery

Transcranial Doppler (TCD) was used to assess collateral flow and to quantitate perfusion velocity changes in a group of 18 patients requiring temporary or permanent surgical occlusion of the internal carotid artery for treatment of their cerebrovascular lesions. Velocity measurements were correlated with times of occlusion and neurological outcome in order to assess safe vessel occlusion times and the need for an intraoperative shunt. These data were used to calculate a perfusion velocity index (PVi), which indicated that values greater than 2 were well tolerated, and values of less than 1 were associated with ischemic signs. In addition, preoperative TCD examinations were combined with compressive maneuvers of the carotid artery in the neck to evaluate the feasibility of carotid clamp ligation for the treatment of giant intracranial aneurysms deemed unsuitable for direct clipping. When maintenance of neurological function and intracranial vessel flow velocities were found to be normal, with aneurysmal flow velocities of zero, ligation of the carotid artery could safely be undertaken. Finally, TCD allowed continuous surveillance of cerebral hemodynamics, which gave immediate assurance of postoperative ICA patency, as well as the ability to identify high velocity states associated with hyperperfusion syndromes, which occurred in two patients.

Transcranial Doppler ultrasonography in the determination of brain death

Transcranial Doppler (TCD) ultrasonography was used to perform multiple examinations of 24 patients who sustained cranial injuries, 23 of whom progressed to death. In the 20 of these 23 patients for whom an adequate TCD signal could be obtained, a characteristic reverberating wave form pattern was observed, with an associated net flow velocity of less than 10 cm/sec in all cases. In the last patient in our study group, a reverberating pattern was also identified, however, a net flow velocity of greater than 20 cm/sec was associated with functional recovery. Correlations of neurological function, TCD tracings, and net flow velocities permitted identification of characteristic hemodynamic changes that preceded cerebral circulatory arrest. Early changes included decreased flow velocity as well as an increase in pulse pressure. Late changes consisted of a persistent increase of pulse pressure with the appearance of retrograde flow velocities during diastole. In the end stage, complete diastolic retrograde flow velocities were found. These gave rise to the characteristic reverberating pattern mentioned earlier. Identification of flow velocity reversal alone, however, proved to be inadequate for making the diagnosis of brain death. Evaluation of net flow velocity (calculated at bedside) was found to be a more sensitive determinant of brain death and closely paralleled the patients' neurological function.