Insulin regulation of triacylglycerol-rich lipoprotein synthesis and secretion.

This review has considered a number of observations obtained from studies of insulin in perfused liver, hepatocytes, transformed liver cells and in vivo and each of the experimental systems offers advantages. The evaluation of insulin effects on component lipid synthesis suggests that overall, lipid synthesis is positively influenced by insulin. Short-term high levels of insulin through stimulation of intracellular degradation of freshly translated apo B and effects on synthesis limit the ability of hepatocytes to form and secrete TRL.

Liver regrowth and apolipoprotein B secretion by rat hepatocytes following partial hepatectomy.

Apolipoprotein (apo) B is an essential component for the assembly and secretion of lipoproteins. The current report examines apo B production using primary cultures of hepatocytes derived from rats 3 to 21 days after partial hepatectomy (PH) to determine the effects of liver regrowth on apo B. Studies indicate that hepatocytes stimulated by PH have a two-thirds reduction in net apo B production 3 to 7 days after surgery, which coincides with the period of maximum rate of liver regrowth.

Spinal anaesthesia for caesarean section in the Solomon Islands.

Results were kept on 43 spinal anaesthetics performed for caesarean section in the Solomon Islands, a developing tropical country in the Pacific Ocean. A 25-gauge Quincke needle was used and either 2.5 ml of heavy bupivacaine 0.

Regulation of VLDL secretion in primary culture of rat hepatocytes: involvement of cAMP and cAMP-dependent protein kinases.

When hepatocytes were cultured for 24 h in the presence of forskolin (10(-4) mol l-1) or isobutylmethylxanthine (IBMX, 10(-3) mol l-1), the intracellular cAMP concentration peaked (320-380 pmol mg-1 protein) after 10-20 min of culture. This increase was accompanied by a decrease in the secretion of triacylglycerol, cholesterol and apoprotein B associated with VLDL. After 4 h cAMP levels had returned almost to basal values but the inhibition of VLDL secretion persisted.

Assignment of the nuclear mitotic apparatus protein NuMA gene to human chromosome 11q13.

A monoclonal antibody that was specific for a nuclear matrix protein was obtained and used to screen a human lambda gt11 expression library. Several partial cDNA clones were isolated and sequenced. The sequence for this protein was shown to be identical to that of NuMA, a 236-kDa nuclear mitotic spindle apparatus protein.

Extract-specific heterogeneity in high-order complexes containing apolipoprotein B mRNA editing activity and RNA-binding proteins.

The mechanism for tissue-specific differences in apolipoprotein B (apoB) mRNA editing efficiency is not known. Structural data are presented which demonstrate tissue-specific, quantitative differences in the high order complexes containing apoB mRNA editing activity and RNA-binding proteins. The bulk of rat enterocyte extract editing activity sedimented at 11 S with an additional 5-10% at 60 S.

Cellular heterogeneity in binding and uptake of low-density lipoprotein in primary rat hepatocytes.

Hepatocellular heterogeneity of biochemical function is well established for many aspects of liver metabolism. This study addresses the question of cellular heterogeneity in the catabolism of low-density lipoprotein by rat hepatocytes. Low-density lipoprotein binding (4 degrees C) and uptake (37 degrees C) by rat hepatocytes were studied by use of human low-density lipoprotein labeled with a highly fluorescent lipophilic probe, N,N-dipentadecylaminostyrylpyridinium iodide, recently developed by us.

Effects of skeletal fixation on craniofacial imaging.

The imaging effects of high-density scatter from different metal compositions of plate and screw fixation systems were assessed in cadaveric craniomaxillofacial skeletons with computed tomographic scanning. Differences in image clarity of three-dimensional reconstructions were observed between titanium, stainless steel, and cobalt-chromium-molybdenum alloy onlay fixation systems, which were not significantly altered with or without an overlying soft-tissue density (facial drape). These differences were reduced in a plaster model, in which the plates were in an intrabony location.

Extracellular fatty acids are not utilized directly for the synthesis of very-low-density lipoprotein in primary cultures of rat hepatocytes.

In hepatocytes cultured in the presence of oleate (initial concn. 0.75 mM), the secretion of very-low-density lipoprotein (VLDL) triacylglycerol and, to a lesser extent, apoprotein B (apoB) increased with time, whereas there was a large decline in the extracellular concentration of fatty acid.

Selective block of nerves in the axillary approach to the brachial plexus.

Background And Objective: Optimal surgical conditions for flexor tendon tenolysis in the hand were achieved by ulnar, radial, and musculocutaneous nerve block at the axilla combined with median nerve block at the wrist.

Result: Because the median nerve function proximal to the wrist was preserved, the patient was able to flex the finger intraoperatively.

Conclusion: Palpation of nerves together with a nerve stimulator were used to localize the nerves accurately.

Prostaglandins suppress VLDL secretion in primary rat hepatocyte cultures: relationships to hepatic calcium metabolism.

In primary cultures of rat hepatocytes, prostaglandin E2 and prostaglandin D2 (PGE2 and PGD2) inhibited the secretion of very low density lipoprotein (VLDL)-associated apoB, triacylglycerol, and cholesterol. These effects were concentration-dependent and remained apparent for at least 3 days of culture without an effect on the apoB/triacylglycerol ratio of the secreted VLDL. Prostaglandins had no effect on the overall synthesis of triacylglycerol but triacylglycerol accumulated within the cells, without intracellular accumulation of apoB.

Immunolocalization, quantitation and cellular heterogeneity of apolipoprotein B in rat hepatocytes.

Hepatocyte autofluorescence represents a major problem in immunofluorescence studies with fluorescein conjugates because of significant spectral overlap. We describe a method for immunostaining hepatocytes with R-phycoerythrin (a fluorochrome with minimal overlap with autofluorescence) with paraformaldehyde fixation and Triton X-100 permeabilization for better antibody penetration. This method produced both perinuclear (presumed Golgi apparatus) and dispersed, reticular staining (presumed endoplasmic reticulum) in rat hepatocytes in culture stained with a monoclonal antibody to rat apolipoprotein B.

Construction and characterisation of a yeast artificial chromosome library containing three haploid maize genome equivalents.

We have constructed a yeast artificial chromosome (YAC) library using high-molecular-weight DNA prepared from agarose-embedded leaf protoplasts of the maize inbred line UE95. This library contains 79,000 clones with an average insert size of 145 kb and should therefore represent approximately three haploid genome equivalents. The library is organised as an ordered array in duplicate microtitre plates.

Impaired hepatic apolipoprotein B and E translation in streptozotocin diabetic rats.

Studies of streptozotocin-induced diabetes in rats have demonstrated that hepatic apo B and apo E production are reduced. To determine if reductions are related to decreases in hepatic mRNAs, we performed blotting analysis of total liver RNA with rat apo B, apo E, and albumin cDNA probes. The expected reduction in albumin mRNA levels to 48% of control livers occurred in diabetic rat liver, while apo B and apo E mRNA levels were unchanged.

The role of pancreatic hormones in the regulation of lipid storage, oxidation and secretion in primary cultures of rat hepatocytes. Short- and long-term effects.

Exposure of cultured rat hepatocytes to a high concentration of insulin (78 nM) for 24 h in the presence of extracellular oleate (0.75 mM) resulted in a decrease in the secretion of apoprotein B (apoB) and triacylglycerol associated with very-low-density lipoprotein (VLDL). However, continuous exposure of the cells to insulin for longer periods (72 h) stimulated the secretion of apoB and triacylglycerol.

Shoulder manipulation to facilitate central vein catheterization from the external jugular vein.

Manipulation of the shoulder to facilitate passage of J-wires past the clavicle during external jugular vein catheterization was tested prospectively in 111 adult patients undergoing cardiac surgery. On 10 of 25 occasions when the wire would not pass into the thorax, manipulation of the shoulder then allowed the wire to pass.

Effect of weight loss on serum lipoprotein(a) concentrations in an obese population.

To assess the distribution of serum concentrations of the atherogenic lipoprotein(a) [Lp(a)] in an obese population and the possible effects of weight reduction, we determined Lp(a) in 52 white, moderately obese subjects (16 men and 36 women). The subjects were participating in a weight-reduction program of diet, exercise, and behavior modification plus combination anorectic drug therapy (fenfluramine and phentermine). This placebo-controlled, double-blind study lasted 104 weeks.

The labeling of lipoproteins for studies of cellular binding with a fluorescent lipophilic dye.

N,N-dipentadecylaminostyrylpyridinium iodide is a dye that is approximately 100-fold more intensely fluorescent in a lipid than aqueous environment. This observation suggests its potential as a fluorescence stain for lipoproteins. This work reports the staining of LDL with this dye for use in studies of cellular binding.

In vitro apolipoprotein B mRNA editing: identification of a 27S editing complex.

Specific apolipoprotein B (apoB) mRNA editing can be performed in vitro on apoB RNA substrates. Native gels and glycerol gradient sedimentation have been used to determine the physical properties of the in vitro editing activity in rat liver cytosolic S100 extracts. ApoB RNA substrates were progressively assembled as 27S complexes for 3 hr with similar kinetics as seen for the accumulation of edited RNA.