Cellular characterization of blastocysts derived from rabbit 4-, 8- and 16-cell embryos and isolated blastomeres cultured in vitro

The purpose of this study was to investigate the developmental potential of isolated rabbit blastomeres under various culture conditions to gain insight into their ability to form the two cell lineages of a viable blastocyst. Intact embryos at the 4-cell, 8-cell, 16-cell stages and blastomeres isolated from 4-, 8- and 16-cell rabbit embryos (1/4, 1/8 or 1/16 blastomeres respectively) were cultured in drops of one of three different media, each supplemented with either fetal calf serum (FCS), bovine serum albumin (BSA) or polyvinyl alcohol (PVA). The effects of the extracellular matrix fibronectin (FN) on the development of isolated rabbit blastomeres were also investigated. Supplementation of the medium with FCS yielded a higher (P < 0.05) proportion of blastocysts than BSA or PVA, predominantly from 1/4 blastomeres. No major differences were found between the three basic culture media. In 1/4, 1/8 or 1/16 blastomeres, blastocyst formation rates were greater (P < 0.05) in groups cultured in matrix-free (54.5, 59.6 and 54.6% respectively) than in FN-coated groups (35.4, 46.0 and 26.1% respectively). Only in blastocysts derived from 1/4 blastomeres, were the numbers of inner cell mass (ICM) and total cells of blastocysts higher (P < 0.05) in FN-coated groups than in matrix-free groups (12.7 +/- 1.1 versus 8.5 +/- 0.7 ICM, 73.8 +/- 3. 7 versus 57.8 +/- 3.3 total cells). The percentage of blastocysts derived from single blastomeres with ICM cells decreased with increasing cell stage of the parent embryos in FN-coated (93.6, 78.3 and 44.0%, respectively) as well as matrix-free groups (96.2, 69.3 and 55.2%). In FN-coated groups, after 96 h (1/4) or 72 h (1/8 and 1/16) of culture, approximately 20-30% of blastomeres did not develop into normal blastocysts but formed sheets with 30-50 cells attached to the bottom of the dishes. These results indicate that the development of rabbit blastomeres shares important characteristics with those from mouse and domestic species and may thus aid in developing an efficient culture system for blastomeres, derived from human embryos.     

A brainstem stereotactic atlas in a three-dimensional magnetic resonance imaging navigation system: first experiences with atlas-to-patient registration

OBJECT: The authors describe a computer-resident digital representation of a stereotactic atlas of the human brainstem, its semiautomated registration to sagittal fast low-angle shot three-dimensional (3-D) magnetic resonance (MR) imaging data sets in 27 healthy volunteers and 24 neurosurgical patients, and an analysis of the subsequent transforms needed to refine the initial registration. METHODS: Contour drawings from the atlas, which offer the 70th percentile of variation of anatomical structures, were interpolated into an isotropic 3-D representation. Initial atlas-to-patient registration was based on the fastigium/ventricular floor plane reference system. The quality of the fit was evaluated using superimposition of the atlas and MR images. If necessary, the atlas was tailored to the individual anatomy by using additional transforms. On average, the atlas had to be stretched by 2 to 6% in the three directions of space. Scale factors varied over a broad range from -8 to +19% and the benefit of visual interactive control of the atlas-to-patient registration was evident. Analysis of distances within the pons measured in the midsagittal MR imaging slices and the required scale factors revealed significant correlations that may be used to reduce the amount of user interaction in the coregistration substantially. In 70.6% of the cases, the atlas had to be shifted in a cranial direction along the brainstem axis (in 25.5% of cases 3-4 mm, in 45.1% of cases 1-2 mm). This was due to a more caudal position of the fastigium cerebelli on the MR images compared with the atlas. CONCLUSIONS: This observation, in conjunction with the variability of the height of the fourth ventricle in our MR imaging data (range 6.1-15.2 mm, mean 10.1 mm, standard deviation 1.8 mm) calls into question the role of the fastigium cerebelli as an anatomical landmark for localization within the brainstem.     

Acute encephalopathy associated with vigabatrin in a six-month-old girl

Summary: Purpose: Vigabatrin (VGB) is a new‐generation anticonvulsant used in the treatment of partial seizures and West syndrome. Side effects of VGB treatment in adults and children are well described. Acute encephalopathy with VGB has recently been reported in eight adults. They developed stupor, confusion, and electroencephalographic abnormalities after starting VGB. Does the acute encephalopathy with VGB also occur in childhood? Methods: We describe a 6‐month‐old girl with infantile Alexander disease with hydrocephalus who developed similar clinical symptoms with apathia, somnolence, and sopor, as well as slowing of the background activity in EEG, 3 days after starting VGB. After exclusion of shunt dysfunction, encephalitis, metabolic dysfunction, and renal failure, VGB was discontinued. Results: During the next 2 days, symptoms subsided, and after 10 days, EEG background activity returned to the one before starting VGB. Conclusions: Acute encephalopathy associated with VGB in children seems to be very rare, but should not be ignored.     

Isoflurane alters the recirculatory pharmacokinetics of physiologic markers

BACKGROUND: Earlier studies have demonstrated that physiologic marker blood concentrations in the first minutes after administration, when intravenous anesthetics exert their maximum effect, are determined by both cardiac output and its distribution. Given the reported vasodilating properties of isoflurane, we studied the effects of isoflurane anesthesia on marker disposition as another paradigm of altered cardiac output and regional blood flow distribution. METHODS: The dispositions of markers of intravascular space and blood flow (indocyanine green), extracellular space and free water diffusion (inulin), and total body water and tissue perfusion (antipyrine) were determined in four purpose-bred coonhounds. The dogs were studied while awake and while anesthetized with 1.7%, 2.6%, and 3.5% isoflurane (1.15, 1.7, and 2.3 minimum alveolar concentration, respectively) in a randomized order determined by a Latin square experimental design. Marker dispositions were described by recirculatory pharmacokinetic models based on very frequent early, and less frequent later, arterial blood samples. These models characterize the role of cardiac output and regional blood flow distribution on drug disposition. RESULTS: Isoflurane caused a significant and dose-dependent decrease in cardiac output. Antipyrine disposition was profoundly affected by isoflurane anesthesia, during which nondistributive blood flow was maintained despite decreases in cardiac output, and the balance between fast and slow tissue volumes and blood flows was altered. CONCLUSIONS: The isoflurane-induced changes in marker disposition were different than those the authors reported previously for halothane anesthesia, volume loading, or hypovolemia. These data provide further evidence that not only cardiac output but also its peripheral distribution affect early drug concentration history after rapid intravenous administration.     

Abnormal septal Q waves in sickle cell disease. Prevalence and causative factors

Electrocardiograms and M-mode echocardiograms were obtained prospectively from 72 patients with hemoglobin SS (n = 55) or SC (n = 17) disease to assess the prevalence of abnormal Q waves in sickle cell disease and to determine if such Q waves could be explained by, or related to, echocardiographically determined anatomic or functional abnormalities. The mean age (+/- SD) of the population under study was 28 +/- 9 years, and the mean hematocrit reading was 28 +/- 5 percent; 43 male and 29 female patients were evaluated. No patient had a history of systemic arterial hypertension, valvular heart disease, or congestive heart failure. Abnormal septal Q waves (amplitude greater than or equal to 0.30 mV; duration less than or equal to 29 msec) were noted in leads V4, V5, or V6 in 15 of 72 patients, and 50 percent (36) of the population under study demonstrated electrocardiographic voltage changes consistent with left ventricular hypertrophy. M-mode echocardiography showed that 29 of 72 patients had a thickened interventricular septum (greater than or equal to 1.2 cm), 16 of 72 had an abnormally thickened left ventricular posterior wall (greater than or equal to 1.2 cm), and 31 of 72 had increased left ventricular mass (greater than 215 g). The prevalence of electrocardiographic and echocardiographic abnormalities was not significantly different between patients with hemoglobin SS and SC disease. Septal excursion was decreased in 11 of the patients, and global left ventricular function (percent fractional shortening) was slightly decreased in three patients. Regional wall motion was normal in all 72 patients. Six percent (four) of the patients met echocardiographic criteria for asymmetric septal hypertrophy. Linear regression analysis yielded significant positive correlations between septal dimension (r = 0.38; p less than 0.001) and left ventricular mass (r = 0.37; p less than 0.005) when each was compared with Q-wave amplitude. A significant negative correlation (r = 0.40; p less than 0.001) was noted between hematocrit reading and Q-wave amplitude. We conclude that abnormal septal Q waves are common in sickle cell disease and are related, in part, to septal thickness, as well as left ventricular mass and degree of anemia.