Consequences of pulmonary inflations (sighs) on cerebral haemodynamics in neonates ventilated by high-frequency oscillation

High-frequency oscillation (HFO) is a technique frequently used in neonatal resuscitation, but which has yet to be evaluated. The use of intrathoracic pressures may have an effect on the cerebral circulation of immature neonates. The aim of this study was to examine the variations in cerebral blood velocity and oxygenation during brief pulmonary inflations (sighs), by focusing on alveolar recruitment. In this prospective study performed in 13 intubated and ventilated neonates (alpha = 5%; 1-beta = 80%), mean blood velocity and Doppler Resistance Index were measured, and variations in chromophores concentrations were evaluated by near infrared spectroscopy. Brief inflations at 4 cm H2O above the mean regulated intra-thoracic pressure did not cause any variation in the parameters measured. An explanation for this discordance with animal studies may be the level of pressure chosen, which could be more appropriate for the pulmonary compliance of neonates.     

Accelerated pubertal development in patients with shunted hydrocephalus

OBJECTIVE: To evaluate pubertal development and peripheral concentrations of gonadotrophins and sex hormones in children with shunted hydrocephalus compared with healthy controls. STUDY DESIGN: 114 patients (52 females, 62 males) and 73 healthy controls (35 females, 38 males) aged 5 to 20 years were analysed for stage of puberty, age at menarche, testicular volume, basal serum follicle stimulating hormone (FSH), luteinising hormone (LH), sex hormone binding globulin (SHBG), testosterone and oestradiol concentrations, and free androgen index. RESULTS: Male gonadal and male and female pubic hair development occurred significantly earlier in the patients than in the controls. The mean age at menarche was significantly lower in the female patients than in their controls (11.7 v 13.2 years; p < 0.001), and lower than it had been for their mothers (v 13.1 years; p < 0.001). Relative testicular volume was higher in the male patients than in their controls (1.2 standard deviation score (SDS) v 0.2 SDS; p < 0.001). The prepubertal patients had higher basal LH (0.13 U/l v 0.08 U/l; p < 0.001) and SHBG (132.3 nmol/l v 109.1 nmol/l; p < 0.01) than the controls. Both the prepubertal and pubertal females had significantly higher basal FSH than their controls (1.57 U/l v 1.03 U/l; p < 0.05, and 4.0 U/l v 2.9 U/l; p < 0.01, respectively). CONCLUSIONS: Hydrocephalic children experience accelerated pubertal maturation, reflected in a younger age at menarche in females and an increased testicular volume in males. This may be because of enhanced gonadotrophin secretion, possibly resulting from unphysiological variations in intracranial pressure.     

Mitral Balloon Valvuloplasty as an Outpatient Procedure Using Inoue Balloon Technique

Objective: To evaluate the safety and feasibility of mitral balloon valvuloplasty (MBV) as an outpatient procedure. Background: MBV is usually done as an inpatient procedure, requiring 3–4 days of hospital admission. Only one report is available about MBV as a day case procedure in the English literature. Methods: Between October 1994 and December 1996, 128 patients underwent MBV using an Inoue balloon. Of those, 31 patients (Group I) had the procedure as outpatients and 97 patients (Group II) as inpatients. Their mean age in Group I was 29 ± 9 years and in Group II 32 ± 10 years (P < 0.3). Atrial fibrillation was present in 4 patients in Group I and in 13 patients in Group II (P < 0.99). Results: Hemodynamic study revealed that mitral valve area increased from 0.9 ± 0.2 to 1.9 ± 0.5 cm²* in Group I and from 0.8 ± 0.2 to 1.7 ± 0.5 cm²* in Group II, Left atrial pressure decreased from 24 ± 5 to 15 ±6 mm Hg* in Group I and 24 ± 6 to 16 ± 5 mmHg in Group II.* Mitral valve gradient decreased from 15 + 5 to 5 + 2 mmHg in Group I and 15 + 5 to 6 + 3 mmHg in Group II* (*P < 0.001). Patients in Group I stayed in the Preadmission Unit for a mean period of 9.5 ± 2.5 hours. Patients in Group II stayed for a mean of 2.5 days in the hospital. Severe mitral regurgitation developed in one patient in each Group and needed semiurgent mitral valve replacement without sequela. No death, convulsions, or thromboembolism were encountered, and three patients in both Groups developed minor hematoma and needed no additional treatment. Conclusion: MBV as an outpatient procedure is feasible and safe and could significantly decrease the cost of medical care.     

一种简化的去大鼠大脑方法

本文介绍一种简化的行之有效的去大鼠大脑方法。与传统方法相比,本法不需结扎颈总动脉或其分支,可简化手术程序,缩短手术时间,避免因手术操作对颈动脉窦区参与呼吸循环功能反射性调节的重要感受器及其传入神经的可能损伤。用此法去大脑后,动物的呼吸频率、心率、动脉血压等可稳定10小时以上,并能成功地进行延髓细胞内记录和标记。本法可用于研究脑干调控功能的急性动物实验。     

CHRONIC ETHANOL CONSUMPTION AMELIORATES THE MATURITY-ONSET DIABETES-OBESITY SYNDROME IN CBA MICE

The effects of a chronic ethanol drinking schedule (20% solutionfor 6 weeks) on energy balance and carbohydrate and lipid metabolismhave been investigated in lean (32–36 g) and obesediabetic(40–44 g) CBA/Ca mice. The untreated obesediabetic miceexhibited hyperglycaemia, hypertriglyceridaemia, hyper-insulinaemiaand insulin resistance. The chronic ethanol treatment, whichyielded plasma ethanol levels of between 1 and 11 mM, loweredthe blood glucose, plasma insulin and tnacylglycerol levelstowards normal in the obese mice, but did not affect these parametersin the lean mice. The body weight of the obese mice tended toreturn to normal during the 6-week drinking period, althoughtheir total energy intake (9.2–10.0 kJ/g/week, food plusethanol-denved calories) was almost double that of the leanmice (4.8–5.4 kJ/g/week). The blood glucose response toacute insulin injection, which was significantly reduced inthe obese mice, became indistinguishable from the response ofnormal mice after chronic ethanol treatment. Soleus muscle glycogensynthesis in both lean and obese mice was not significantlyaltered by ethanol drinking, but brown adipose tissue lipogenesiswas significantly increased (by 50%) in the obese mice. It isproposed that ethanol is acting chronically to restore insulinsensitivity in the obese diabetic mice at doses which have littleor no effect in normal lean animals. This action is exerted,at least in part, at the level of brown adipose tissue lipogenesis.     

Work in progress: the application of temporal filtering techniques to hybrid subtraction in digital subtraction angiography

Temporal filtering methods were applied to iodine signal-to-noise ratio (SNR) restoration in intravenous hybrid subtraction digital subtraction angiography (DSA). For equal detected exposure rates hybrid subtraction had approximately 35% of the SNR of temporal subtraction. When matched filtering was applied to a DSA run, the filtered result had approximately two times higher SNR than the peak contrast image in the run. Thus, when matched filtering techniques were applied to the hybrid image sequence, the resultant SNR increased to about 70% of that of temporal subtraction. With an additional factor-of-two increase in exposure rate for the hybrid run, SNR parity with temporal subtraction could be achieved. This compared with a factor-of-nine increase in exposure that would be required if no filtering were performed. Experimental hybrid matched filter results, generated with intravenous canine DSA studies, supported the predictions in SNR performance.     

Involvement of endothelium-derived NO in the basal tone and in the vasodilator responses to muscarinic agonists in the rat isolated mesenteric arterial bed

Summary— To investigate the involvement of nitric oxyde (NO) derived from endothelial cells in the control of vascular tone in the rat mesenteric vascular bed, the effects of different procedures known to interfere with the NO-cyclic GMP pathway were evaluated both on the basal tone and on the vasodilatory responses to four muscarinic agonists. To this aim, rat isolated mesenteric vascular beds were perfused at constant pressure. Water infusion significantly increased the resting perfusion pressure whereas L-NOARG, L-NAME and methylene blue were devoid of effect. In noradrenaline-preconstricted vascular bed, the perfusion pressure was significantly increased after water or L-NAME infusion. The vasodilator response induced by subsequent addition of acetylcholine in bolus was not significantly modified by pre-treatment with indomethacin but was significantly reduced by water infusion. Reponses to acetylcholine and to three other muscarinic agonists -carbachol, oxotremorine or McNeil A 343- were assessed. Incubation with L-NAME did not modify the initial peak falls of the agonists except for Mc Neil A 343, whereas it significantly reduced the area under the pressure trace for all the substances. The latter effect was reversed after a subsequent incubation with L-Arginine. Finally, L-NAME strongly and significantly increased the drop in perfusion pressure and the area under the pressure trace following bolus of glyceryl trinitrate. These results suggest that in the mesenteric arterial bed of the rat, which can be considered as a resistant arteries preparation, basal tone appears to be controlled by a factor other than NO. Moreover, the vasodilator responses of muscarinic agonists are affected by L-NAME in their second late sustained phase only, which probably relies on a de novo synthesis of endothelium derived-NO. Finally, endothelium derived-NO exerts inhibitory effects both on the sensitivy of the vascular smooth muscle to glyceryl trinitrate and on the magnitude of its contraction in the presence of noradrenaline, two types of effects which are sensitive to L-NAME.