Morphometric analysis of rat hepatocytes after total billary obstruction

Using light and electron microscopic morphometric techniques, the effects of 48 hr of extrahepatic biliary obstruction on hepatocyte structure were examined in the rat. Liver cells near the portal area were compared to those in the centrilobular regions of the hepatic lobule. Observations on the normal animals confirm earlier evidence of quantitative differences in the surface density of organelles in hepatocytes located within different regions of the lobule. A striking difference in the quantity of the Golgi complex in the two areas of the lobule was noted for the first time, with the portal cells containing a significantly greater quantity of this organelle than centrolobular hepatocytes. After 48 hr of total obstruction, most of the previously reported qualitative changes in the canalicular and pericanalicular regions were confirmed. Morphometric analysis at the light-microscopic level showed an increase in the number of cells and a decrease in cell size in those cells near the portal area were compared to those in the centrolobular regions of the helar level demonstrated a significant decrease in both rough and smooth surfaced endoplasmic reticulum in cells of both zones, a finding in marked contrast to the hypertrophy of smooth endoplasmic reticulum suggested by other investigators on the basis of qualitative assessments. There was also a striking decrease in the amount of the Golgi complex, limited to cells in the portal regions. In addition, in all zones a decrease in the volume density of mitochondria and lysosomes was noted, whereas the volume of microbodies was increased. It is suggested that this loss in total membrane material within the cell may be secondary to the degranulation and decrease in total surface area of rough surfaced endoplasmic reticulum, an organelle thought to be responsible in part for the synthesis of new cellular membranes. These observations suggest that present concepts concerning the pathogenesis of cholestatic liver disease require reappraisal.     

The maternal and fetal levels of human chorionic gonadotropin, human placental lactogen and prolactin during the perinatal period (author's transl)

The levels of human chorionic gonadotropin (HCG), human placental lactogen (human choriosomatomamotropin HCS) and prolactin (PRL) were determined in the serum of 72 maternity patients and the serum of the newborn infants. The determinations were done with radioimmunologic tests (RIA). These three protein hormones were also determined in the amniotic fluid and in the maternal serum from 4-6 days prior to the delivery of the infant. The concentration of HCG or HCS in the serum of the newborn infants was a mean 0.43 or 0.37% of the level in the maternal serum. The concentration of PRL in the serum of the newborn was 118% and slightly higher than in the serum of the mothers. The concentration in the amniotic fluid was 1.5% for HCG, 5.8% for HCS, and 252% for PRL, compared to the corresponding levels in the maternal serum. The fact that the hormone concentrations in the amniotic fluid are significantly higher than in the serum of the newborn suggests excretion of the hormones from the fetal circulation via the fetal liver and the fetal kidney. The high levels of PRL in the maternal and the newborn serum may be caused by the high concentrations of estrogen or progesterone. Increased during the course of the pregnancy there was a significant sex linked difference in the level of HCG in the maternal serum correlated to the sex of the newborn infant.     

Persistent thrombin generation in humans during specific thrombin inhibition with hirudin

BACKGROUND: The degree to which antithrombotic drugs suppress thrombin generation is unknown. Because hirudin, unlike antithrombin III, binds intravascular thrombin rapidly and selectively to yield a circulating inactive complex of 3- to 4-hour half-life, we used intravenous hirudin in humans to investigate the course of thrombin generation during and early after anticoagulation with this potent, direct antithrombin. METHODS AND RESULTS: Intravascular thrombin was measured with an ELISA for the thrombin-hirudin complex formed during and for 18 hours after stopping a 6-hour infusion of hirudin at 0.1, 0.2, and 0.3 mg.kg-1.h-1 in three groups of six patients each. With free hirudin in 20- to 10,000-fold molar excess of thrombin and peak activated partial thromboplastin times of 2.3 to 3.0 times baseline, mean plasma thrombin-hirudin complex increased from 794 +/- 85 pg/mL (mean +/- SEM) 15 minutes after the start of the infusion to 1617 +/- 151 pg/mL at 6 hours of infusion to 2667 +/- 654 pg/mL at 24 hours. During the 24-hour observation period, plasma concentration of fragment 1.2 (the peptide released during conversion of prothrombin to thrombin) never fell below baseline but rather increased transiently during the hirudin infusion. Plasma concentrations of thrombin-antithrombin III complex (in ng/mL) decreased from 4.34 +/- 0.40 at baseline to 1.64 +/- 0.13 at 6 hours (P < .001) and gradually increased after stopping the infusion to 5.7 +/- 0.87 at 24 hours (nonsignificant compared with baseline). CONCLUSIONS: Measurement of thrombin-hirudin complex may be used as a marker of thrombin generation in humans. Persistent accumulation of thrombin-hirudin complex and generation of fragment 1.2 during and after completion of potent anticoagulation with hirudin suggest thrombin generation is not blocked by high-affinity thrombin inhibition. The persistent formation of thrombin during declining plasma levels of hirudin may contribute to the pathogenesis of rethrombosis early after antithrombin therapy or during inadequate anticoagulation.     

Epilepsy in very preterm infants: neonatal cranial ultrasound reveals a high-risk subcategory

Osteoporotic fractures, and in particular, hip fractures result in significant morbidity and mortality. Low bone mass is the main risk factor of enhanced bone fragility, resulting in an increased risk for hip fracture. Bone density of osteoporotic women with and without hip fractures show a considerable overlap. Therefore, other bone-independent factors also play an important role for the development of hip- and other osteoporotic fractures. One other important factor is falling. In 90% of hip fractures falling was involved [10-15], but only 5% or less of these falls resulted in a subsequent fracture. The view that adequate exercise is beneficial for skeletal health of children and for prevention and treatment of osteoporosis in adults is supported primarily by two lines of evidence: longitudinal and cross-sectional trials in children and young adult athletes showing a significant increase of muscle- and bone mass after strenuous (children) or chronic exercise (athletes) as compared to normally active (children) or sedentary control subjects. What are the potential benefits and limits of specific exercise programs with respect to bone mass, prevention of falls and fractures? In this review these questions are discussed and a specific exercise program in osteoporotic patients with fractures is delineated.     

Mechanism of Rab geranylgeranylation: formation of the catalytic ternary complex

Rab proteins are geranylgeranylated on one or two C-terminal cysteines by Rab geranylgeranyl transferase (RabGGTase). The reaction is dependent on a Rab-binding protein, termed Rab escort protein (REP). Here, we studied the role of REP in the geranylgeranylation reaction. We first characterized the interaction between REP and ungeranylgeranylated Rab using analytical ultracentrifugation and a fluorescence-based assay. We measured an equilibrium dissociation constant of 0.2 microM for the formation of a 1:1 REP-Rab complex and showed that this interaction relies mostly on ionic bonds and does not involve the two C-terminal cysteine residues. Second, we show that REP is required for recognition of Rab by RabGGTase and therefore that the REP-Rab complex is the true substrate for RabGGTase. Third, we show that free REP inhibits the geranylgeranylation reaction, suggesting that the complex is recognized by RabGGTase primarily via a REP-binding site. Our data suggest a model whereby REP behaves kinetically as an essential activator of the reaction.     

Distraction osteogenesis for lengthening of the hard palate: Part I. A possible new treatment concept for velopharyngeal incompetence. Experimental study in dogs

Many procedures have been described to correct velopharyngeal incompetence. Significant complications can occur, and the results may not be satisfactory. If the short soft palate has satisfactory muscle function and if it could be moved toward the posterior pharyngeal wall by distraction osteogenesis of the hard palate, an entirely new concept of treatment for velopharyngeal incompetence would be available. The object of the present study was to explore the possibility of osteogenesis occurring in the hard palate in dogs after gradual distraction (callus distraction). Six adult, mix-bred dogs were anesthetized, and the palatal mucosa was elevated. A midpalatal transverse osteotomy and two lateral osteotomies were performed. Tantalum bone markers for cephalometric analysis were placed, and an individually fabricated, orthodontic-like distraction device with an expansion screw in the sagittal direction was inserted. The device was stabilized on the premolars and fixed to the palatal bone with titanium miniscrews. Gradual distraction began after a latency period of 10 to 18 days. The rate of the distraction varied from 0.25 to 0.75 mm per day. The device was left in place for 6 to 8 weeks after expansion to allow for bony consolidation. Assessment was by direct examination, cephalograms, computed tomography, and histology with bone labeling. Impressions of the jaws were taken preoperatively and after device removal to examine plaster cast changes in the dental occlusion. Cephalometric and computed tomographic scan analysis demonstrated a distraction of up to 8 mm. All gaps were filled with de novo osteogenesis. Comparison of the plaster casts revealed no change in the occlusion. At 1 month after distraction, the computed tomographic scan showed the first signs of ossification of the experimental gap from the anterior and posterior bone ends. After 4.5 months ossification was almost complete with a small translucent zone in the middle of the experimental gap. After 7 months ossification was complete.