Modifications of cerebral vascular resistance and autoregulation after graft reperfusion during human orthotopic liver transplantation.

We have studied cerebral blood flow velocity (CBFV) and cerebral autoregulation (CA) in 23 orthotopic liver transplantation (OLT) patients using transcranial doppler. CBFV was continuously recorded using a fixed (helmet) 2-Mz probe through the trans-temporal window. CA changes were studied using a linear regression analysis of percentile changes in CBFV and mean arterial blood pressure (MABP) after phenylephrine infusion compared with baseline. Pearson's "r" coefficient was considered an index of CA. In case of autoregulation is lost "r" tends to 1, thus representing complete dependence of CBFV on MABP. We regarded the slope coefficient parameter "S" as an index of cerebral vascular resistance (CVR), namely, the ratio of the corresponding variations of CBFV to MABP. Wilcoxon test showed a significant increase in both "r" and "S" between the anhepatic versus postreperfusion phases (within the first hour) and versus recovery in the neohepatic phase (end of surgery). A decreased CVR was observed within the first hour after graft reperfusion producing a loss of CA. These phenomena lead to an increase of CBFV and exposed the brain to hyperperfusion.

Portal vein pressure and graft oxygen consumption monitoring during liver transplantation.

UNLABELLED: Abnormal splanchnic circulation (ASC) is often detected too late, when hepatic circulation is already irreversibly compromised. If we could detect surgical or metabolic problems early after graft reperfusion, we might be able to correct them immediately before the damage becomes irreversible. The aim of this study was to determine if ASC can be predicted early after liver transplantation (LT) using portal vein pressure measurements and graft oxygen consumption monitoring. PATIENTS AND METHODS: Twenty-patients (13 men, 7 women of mean age 46 years) undergoing LT with the piggyback technique for hepatitis C virus (HCV)/hepatitis B virus (HBV)-related cirrhosis were retrospectively divided in two groups. Group A (16 patients), in which LT was successful, and group B (4 patients) in which LT was unsuccessful because of primary nonfunction (2 patients), infrahepatic portal vein thrombosis (1 patient), or hepatic vein kinking (1 patient). We then compared the portal blood pressure values and the prehepatic and posthepatic oxygen content difference (p-pDO(2)) before portal clamping; at the end of anhepatic phase; 5, 15, and 25 minutes after portal vein (PV) reperfusion; and 5, 20, 40, and 100 minutes after hepatic artery anastomosis. RESULTS: Early after graft reperfusion; portal pressure decreased to levels lower than that at baseline in group A, but remained high until the end of surgery in group B. At the end of surgery, p-pDO(2) increased more among group B than group A. CONCLUSION: ASC, specifically an increased PV resistance, can be predicted early after LT by portal vein pressure measurements and graft oxygen consumption monitoring.

[The ketogenic diet in infantile refractory epilepsy: electroclinical response, complications and secondary effects]. / Dieta cetogénica en la epilepsia refractaria infantil: respuesta electroclínica, complicaciones y efectos secundarios.

INTRODUCTION: The ketogenic diet (KD) was developed after observation that prolonged starvation might lead to the seizures stopping. Due to is efficacy and safety, KD plays an important part in the management of children with refractory epilepsy. OBJECTIVES: To show the clinical anticonvulsant response of KD, the electroencephalographic changes, the need for strict methodology to enhance the success of the treatment, and evaluation of the side effects and complications observed. PATIENTS AND METHODS: After being started on a protocol of a classical ketogenic diet, 13 patients aged between 1 and 19 years were prospectively evaluated for an average period of 22 months. All had different types of refractory epilepsy according to Schmidt's scores, as modified by Aicardi. RESULTS: There was over 50% reduction in the number of crises of 84.5% of the children. Complete control was attained in 30.8%. The electroencephalographic recordings showed improvement in 100% of the children. The families involved reported a 58.8% reduction in the side effects observed. During treatment the serum cholesterol rose in 72.7% of the children, 36.4% complained of constipation, 27.3% had a brief period of anorexia and there was symptomatic metabolic acidosis during intercurrent infection and renal lithiasis in one patient. CONCLUSION: The clinical and electroencephalographic improvement and minimal side-effects seen confirm that KD is beneficial in refractory epilepsy in children.

[The electroencephalographic evolution of a group of patients on a ketonic diet]. / Evolución electroencefalográfica de un grupo de pacientes en dieta cetogénica.

INTRODUCTION: A ketogenic diet is an old method for the treatment of resistant epilepsy in children, which has been revived in recent years because of its proven efficacy. OBJECTIVE: To correlate electroencephalographic findings and clinical changes observed in a group of patients on the classical ketogenic diet, to determine the validity of the electroencephalogram in following-up treatment. PATIENTS AND METHODS: We made a prospective evaluation of 11 patients aged between 1 and 19 years for an average period of 22 months. The patients had different types of resistant epilepsy according to Schmidt's score as modified by Aicardi, with a sleep encephalogram prior to treatment and 3, 6, 12 and 24 months later, after following the protocol of the classical ketogenic diet. RESULTS: The sleep encephalograph recordings showed changes in all patients. In 9% of cases they became normal, there was great improvement in 45.45% and some improvement in 45.45%. No patient had worsening of the recording. There was over 50% reduction in the number of seizures seen in 72.7% of the children and complete control was achieved in 27.3%. CONCLUSIONS: Normalization or improvement of sleep encephalogram recordings was correlated with improvement in seizures. Electroenchephalogram follow-up is a useful method for prediction of response to treatment with a ketogenic diet.

Isolation and characterization of Caulobacter crescentus flagellar hooks.

The basal hook structure of the flagellar organelle Caulobacter crescentus was isolated from release flagella. Hook preparations contained a single major proteins species of 73,000 molecular weight and proteins in smaller amounts that may be minor hook components. Hooks isolated from C. crescents CB13B1a and CB15 were immunologically cross-reactive.

Interaction between two major outer membrane proteins of Escherichia coli: the matrix protein and the lipoprotein.

The affinity to the matrix protein, one of the major outer membrane proteins of Escherichia coli, for the peptidoglycan was examined of extracting the cell envelope complex at 55 degrees C and 2% sodium dodecyl sulfate containing different amounts of NaCl. It was found that the matrix protein was extracted from the peptidoglycan of a mutant strain (lpo) that lacks another major membrane protein, the lipoprotein, at a lower NaCl concentration than was the matrix protein of the wild-type cell (lpo+). When the envelope fraction of the wild-type strain was treated with trypsin, which is known to cleave the bound-form lipoprotein from the peptidoglycan, the affinity of the matrix protein for the peptidoglycan decreased to the same level as that of the affinity of the matrix protein for the peptidoglycan of the mutant strain. It was further shown that the free-form lipoprotein was also retained in the matrix protein-peptidoglycan complex, although the extent of retention of the free form of the lipoprotein was less than that of the matrix protein. These results indicate that both the free and the bound forms of the lipoprotein are closely associated with the matrix protein and that the bound form of the lipoprotein plays and important role in the association between the matrix protein and the peptidoglycan.

Lipoprotein from the outer membrane of Escherichia coli: purification, paracrystallization, and some properties of its free form.

In the envelope of Escherichia coli, is a lipoprotein of molecular weight 7,200 as a major envelope protein. This lipoprotein was previously shown to exist in two different forms in the outer membrane of E. coli: the free form and the boundform, which is covalently linked to the peptidoglycau. The free form of the lipoprotein has been purified and paracrystallized by adding acetone to a sodium dodecyl sulfate solution in the presence of magnesium ion. The paracrystals were needle shaped. An electron micrograph of the negatively stained paracrystals showed a highly ordered ultrastructure. The chemical structure of the free form was compared with that of the bound form by (i) the amino acid composition, (ii) the fatty acid composition, and (iii) the peptide analysis after cyanogen bromide cleavage. The alpha-helical content of the free form of the lipoprotein was measured from the circular dichroism spectrum of the lipoprotein in 0.01% sodium dodecyl sulfate and found to be 87%. Using the purified lipoprotein as antigen, antiserum against the free form of the lipoprotein was obtained. Immunoprecipitation of the lipoprotein with the antiserum was found to be very specific, since only the free form of the lipoprotein was found as a major peak when the antiserum was reacted with the whole envelope proteins solubilized in 0.2% sodium dodecyl sulfate, and the immunoprecipitate thus formed was analyzed by polyacrylamide gel electrophoresis.

Ultrastructure of paracrystals of a lipoprotein from the outer membrane of Escherichia coli.

The highly purified lipoprotein of the outer membrane of Escherichia coli forms paracrystals. The ultrastructures of these paracrystals were examined by electron microscopy. The needle-shaped paracrystals show several different band patterns, depending on conditions of paracrystallization. Models are presented to explain possible arrangements of the lipoprotein molecules within the paracrystals.

Lysozymes from bacteriophages T3 and T5.

Lysozymes produced in host cells infected with bacteriophages T3 and T5 were found to have the same enzymatic specificity toward the peptidoglycan from Escherichia coli as T7 phage lysozyme, which has been shown to be an N-acetylmuramyl-L-alanine amidase.