An Improved Crop Scouting Technique Incorporating Unmanned Aerial Vehicle-Assisted Multispectral Crop Imaging into Conventional Scouting Practice for Gummy Stem Blight in Watermelon.

Multispectral imaging is increasingly used in specialty crops, but its benefits in assessment of disease severity and improvements in conventional scouting practice are unknown. Multispectral imaging was conducted using an unmanned aerial vehicle (UAV), and data were analyzed for five flights from Florida and Georgia commercial watermelon fields in 2017. The fields were rated for disease incidence and severity by extension agents and plant pathologists at randomized locations (i.e., conventional scouting) followed by ratings at locations that were identified by differences in normalized difference vegetation index (NDVI) and stress index (i.e., UAV-assisted scouting). Diseases identified by the scouts included gummy stem blight, anthracnose, Fusarium wilt, Phytophthora fruit rot, Alternaria leaf spot, and cucurbit leaf crumple disease. Disease incidence and severity ratings were significantly different between conventional and UAV-assisted scouting (P < 0.01, Bhapkar/exact test). Higher severity ratings of 4 and 5 on a scale of 1 to 5 from no disease to complete loss of the canopy were more consistent after the scouts used the multispectral images in determining sampling locations. The UAV-assisted scouting locations had significantly lower green, red, and red edge NDVI values and higher stress index values than the conventional scouting areas (P < 0.05, ANOVA/Tukey), and this corresponded to areas with higher disease severity. Conventional scouting involving human evaluation remains necessary for disease validation. Multispectral imagery improved watermelon field scouting owing to increased ability to identify disease foci and areas of concern more rapidly than conventional scouting practices with early detection of diseases 20% more often using UAV-assisted scouting.

National Quality Measures for Breast Centers (NQMBC): a robust quality tool: breast center quality measures.

INTRODUCTION: Measuring and improving quality of care is of primary interest to patients, clinicians, and payers. The National Consortium of Breast Centers (NCBC) has created a unique program to assess and compare the quality of interdisciplinary breast care provided by breast centers across the country. METHODS: In 2005 the NCBC Quality Initiative Committee formulated their initial series of 37 measurements of breast center quality, eventually called the National Quality Measures for Breast Centers (NQMBC). Measures were derived from published literature as well as expert opinion. An interactive website was created to enter measurement data from individual breast centers and to provide customized comparison reports. Breast centers submit information using data they collect over a single month on consecutive patients. Centers can compare their results with centers of similar size and demographic or compare themselves to all centers who supplied answers for individual measures. New data may be submitted twice yearly. Serially submitted data allow centers to compare themselves over time. NQMBC random audits confirm accuracy of submitted data. Early results on several initial measures are reported here. RESULTS: Over 200 centers are currently submitting data to the NQMBC via the Internet without charge. These measures provide insight regarding timeliness of care provided by radiologists, surgeons, and pathologists. Results are expressed as the mean average, as well as 25th, 50th, and 75th percentiles for each metric. This sample of seven measures includes data from over 30,000 patients since 2005, representing a powerful database. In addition, comparison results are available every 6 months, recognizing that benchmarks may change over time. CONCLUSIONS: A real-time web-based quality improvement program facilitates breast center input, providing immediate comparisons with other centers and results serially over time. Data may be used by centers to recognize high-quality care they provide or to identify areas for quality improvement. Initial results demonstrate the power and potential of web-based tools for data collection and analysis from hundreds of centers who care for thousands of patients.

A dominant negative human peroxisome proliferator-activated receptor (PPAR){alpha} is a constitutive transcriptional corepressor and inhibits signaling through all PPAR isoforms.

Several missense mutations in the ligand-binding domain of human peroxisome proliferator-activated receptor (PPAR)gamma have been described in subjects with dominantly inherited severe insulin resistance associated with partial lipodystrophy, hypertension, and dyslipidemia. These mutant receptors behave as dominant-negative inhibitors of PPARgamma signaling when studied in transfected cells. The extent to which such dominant-negative effects extend to signaling through other coexpressed PPAR isoforms has not been evaluated. To examine these issues further, we have created a PPARalpha mutant harboring twin substitutions, Leu459Ala and Glu462Ala, within the ligand binding domain (PPARalpha(mut)), examined its signaling properties, and compared the effects of dominant-negative PPARalpha and PPARgamma mutants on basal and ligand-induced gene transcription in adipocytes and hepatocytes. PPARalpha(mut) was transcriptionally inactive, repressed basal activity from a PPAR response element-containing promoter, inhibited the coactivator function of cotransfected PPAR-gamma coactivator 1alpha, and strongly inhibited the transcriptional response to cotransfected wild-type receptor. In contrast to PPARgamma, wild-type PPARalpha failed to recruit the transcriptional corepressors NCoR and SMRT. However, PPARalpha(mut) avidly recruited these corepressors in a ligand-dissociable manner. In hepatocytes and adipocytes, both PPARalpha(mut) and the corresponding PPARgamma mutant were capable of inhibiting the expression of genes primarily regulated by PPARalpha, -gamma, or -delta ligands, albeit with some differences in potency. Thus, dominant-negative forms of PPARalpha and PPARgamma are capable of interfering with PPAR signaling in a manner that is not wholly restricted to their cognate target genes. These findings may have implications for the pathogenesis of human syndromes resulting from mutations in this family of transcription factors.

Synthesis and function of hepatic very-low-density lipoprotein.

Most of the triacylglycerol (TAG) utilized for the assembly of very-low-density lipoprotein (VLDL) in the secretory apparatus of the hepatocyte is mobilized by lipolysis of the cytosolic TAG pool, followed by re-esterification. The lipases involved include arylacetamide deacetylase and/or triacylglycerol hydrolase. Some of the re-esterified products of lipolysis gain access to an apolipoprotein-B-rich VLDL precursor to form mature VLDL. Some, however, are returned to the cytosolic pool in a process that is stimulated by insulin and inhibited by microsomal triacylglycerol transfer protein (MTP). Phospholipids also contribute to VLDL TAG in a process which involves ADP-ribosylation factor-1 (ARF-1)-mediated activation of phospholipase D. The temporary storage of TAG in the liver, followed by its mobilization and secretion as VLDL, form part of a process by which the liver protects vulnerable body tissues from excess lipotoxic non-esterified ('free') fatty acids in the plasma.

Disturbances in the normal regulation of SREBP-sensitive genes in PPAR alpha-deficient mice.

Peroxisome proliferator-activated receptor alpha (PPAR alpha)-null mice were used to investigate the nature of the relationship between the normal circadian rhythm of hepatic PPAR alpha expression and the expression of the lipogenic and cholesterogenic sterol regulatory element-binding protein (SREBP)-regulated genes, acetyl-CoA carboxylase, fatty acid synthase (FAS), and 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoAR). The expression of FAS and HMG-CoAR varied rhythmically over the diurnal cycle in the normal mice, with patterns that were the opposite of that of PPAR alpha. The diurnal variation of lipogenic and cholesterogenic gene expression was attenuated or abolished in the PPAR alpha-null mice. This resulted in decreased expression compared with normal mice, but only during the dark phase of the cycle, when food intake was high. The diurnal variation in hepatic fatty acid and cholesterol synthesis was also abolished in the PPAR alpha-null animals and the variations in the concentration of plasma triacylglycerol, nonesterified fatty acids, and cholesterol were all attenuated. The failure of HMG-CoAR expression to increase during the feeding period in the PPAR alpha-null mice was associated with a decrease in hepatic nonesterified cholesterol content and an increase in cholesteryl ester compared with normal mice. There was no defect in the downregulation of hepatic HMG-CoAR mRNA in response to dietary cholesterol in the PPAR alpha-null mice. Under these conditions, hepatic PPAR gamma expression increased in both the control and PPAR alpha-deficient mice. The results suggest that PPAR alpha-deficiency disturbs the normal circadian regulation of certain SREBP-sensitive genes in the liver, but does not affect their response to dietary cholesterol. -- Patel, D. D., B. L. Knight, D. Wiggins, S. M. Humphreys, and G. F. Gibbons. Disturbances in the normal regulation of SREBP-sensitive genes in PPAR alpha-deficient mice. J. Lipid Res. 2001. 42: 328--337.

Cost analysis of glaucoma medications.

PURPOSE: To evaluate the yearly cost in 1998 of glaucoma medications to patients and to the Health Plan at a university-affiliated teaching hospital with its own health maintenance organization. MATERIALS AND METHODS: Data concerning Health Plan glaucoma-medication prescriptions for 1998 were retrieved from the hospital pharmacy database. RESULTS: The most costly medication per patient per year was latanoprost (Xalatan; Pharmacia & Upjohn, Kalamazoo, MI [$337]), followed by betaxolol hydrochloride (Betoptic-S; Alcon, Fort Worth, TX [$336]), dorzolamide (Trusopt; Merck & Co., West Point, PA [$288]), brimonidine tartrate (Alphagan; Allergan Pharmaceuticals, Irvine, CA [$260]), timolol maleate 0.5% in a gel-forming solution (Timoptic-XE 0.5%; Merck & Co., West Point, PA [$199]), levobunolol hydrochloride (Betagan; Allergan Pharmaceuticals, Irvine, CA [$195]), and generic timolol maleate 0.5% ($132). Cost per unit was greatest for Betoptic-S ($51), exceeding that of Trusopt ($43) and Xalatan ($43), Alphagan ($42), Betagan ($38), Timoptic-XE 0.5% ($32), and timolol maleate 0.5% ($27). CONCLUSION: Variability in the cost of medications may influence the long-term medical management of glaucoma patients.

Do attitude and area influence health? A multilevel approach to health inequalities.

This paper demonstrates an area effect on health and suggests improvements in research practice for work in this field. We use an area classification which can be related clearly to factors that influence the health of individuals and take account of people's differing propensities to draw influence from their area. Multilevel analysis demonstrates that the degree of deindustrialisation which an area experienced in Britain, in the 1980s, has an independent association with the health of resident individuals. A significant relationship between a person's attitude to their community and their health is shown to be independent of individual and area characteristics. We conclude that both individual and area characteristics influence health.

Use of calibrated viral load standards for group M subtypes of human immunodeficiency virus type 1 to assess the performance of viral RNA quantitation tests.

Optimal management of human immunodeficiency virus type 1 (HIV-1) disease requires accurate quantitation of viral RNA concentrations in plasma. Evidence for increasing geographic intermixing of HIV-1 subtypes makes equivalent quantitation of all subtypes essential. The performances of six quantitative viral RNA tests are described, for the first time, with calibrated viral isolates of diverse subtypes.

Co-ordination of hepatic and adipose tissue lipid metabolism after oral glucose.

The integration of lipid metabolism in the splanchnic bed and in subcutaneous adipose tissue before and after ingestion of a 75 g glucose load was studied by Fick's principle in seven healthy subjects. Six additional subjects were studied during a hyperinsulinemic euglycemic clamp. Release of non-esterified fatty acids (NEFA) from adipose tissue and splanchnic NEFA extraction followed a similar time-course after oral glucose, and there was a highly significant relationship between adipose tissue NEFA release and splanchnic NEFA uptake. There was no immediate inhibition of splanchnic very low density lipoprotein (VLDL)-triacylglycerol (TAG) output when plasma insulin levels increased after glucose. Adipose tissue extraction of VLDL-TAG tended to vary in time in a manner similar to splanchnic VLDL-TAG output and the two were significantly related. The area-under-curves (AUC) for splanchnic extraction of NEFA was significantly lower than that for output of VLDL, implying depletion of hepatic TAG stores during the experiment. In the hyperinsulinemic clamp experiments, there was on average suppression of splanchnic VLDL-TAG output although between-person variability was marked. This suppression could be explained by a very low supply of NEFA during the clamp. We conclude that there is an integrated pattern of metabolism in splanchnic and adipose tissues in the postabsorptive and post-glucose states. Flux of NEFA from adipose tissue drives splanchnic NEFA uptake. Splanchnic VLDL-TAG secretion appears to be regulated by a number of factors and in turn controls TAG extraction in adipose tissue. Insulin does not seem to play a key role in the acute regulation of hepatic VLDL metabolism under these particular conditions in vivo.

Manipulation of cholesterol and cholesteryl ester synthesis has multiple effects on the metabolism of apolipoprotein B and the secretion of very-low-density lipoprotein by primary hepatocyte cultures.

Inhibition of esterified and non-esterified cholesterol synthesis by lovastatin in primary rat hepatocytes suppressed the net synthesis and very-low-density lipoprotein (VLDL) secretion of apolipoprotein B (apoB)-48 and apoB-100. Lovastatin did not alter the rates of apoB-48 and apoB-100 post-translational degradation. 25-Hydroxycholesterol, which inhibited non-esterified cholesterol synthesis but increased the synthesis of cholesteryl ester, showed differential effects on the metabolism of apoB-48 and apoB-100. Whereas the secretion of apoB-48 VLDL was suppressed there was no effect on the secretion of apoB-100 VLDL. The post-translational degradation of apoB-48, but not of apoB-100, was enhanced by 25-hydroxycholesterol. The net synthesis rates of apoB-48 and apoB-100 were unaffected by 25-hydroxycholesterol. The inhibitory effect of lovastatin alone on the net synthesis of apoB-48 and apoB-100 was reversed by the simultaneous presence of 25-hydroxycholesterol, suggesting a role for newly synthesised cholesteryl ester. Prevention of the reversal effect by the acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor YM 17E supported this interpretation. In the presence of lovastatin, restoration of the net synthesis of apoB by 25-hydroxycholesterol was not accompanied by an increased VLDL output of apoB-48 and apoB-100. However, under these conditions there was an increased post-translational degradation of apoB-48 and apoB-100. These results suggest that interference with intracellular cholesterol and cholesteryl ester metabolism interrupts VLDL assembly at sites of both apoB net synthesis and post-translational degradation.

Metabolic characteristics of a human hepatoma cell line stably transfected with hormone-sensitive lipase.

Clones of HepG2 cells were selected that stably express the cDNA for hormone-sensitive lipase (HSL). When cells were cultured in the presence of labelled extracellular oleate, accumulation of labelled fatty acid as cellular triacylglycerol (TAG) was significantly lower in the transfectants compared with the wild-type cells. There was no change in the net rate of phospholipid (PL) synthesis. Culture of cells containing isotopically prelabelled TAG resulted in a greater net loss of TAG from the transfected cells than from the wild-type cells. The excess loss of labelled TAG was primarily due to an increased TAG fatty acid oxidation. Free fatty acid release into the medium was not increased in the transfectants, nor was the very low rate of lipoprotein lipid secretion. Also, there was no increased net trafficking of fatty acids from TAG into PLs. Changes in the 3H:14C ratio of TAG prelabelled with [3H]glycerol and [14C]oleate suggested that none of excess TAG fatty acid released in the transfected cells underwent intracellular re-esterification to TAG prior to oxidation. The results suggest that fatty acids mobilized by HSL are directed immediately into the oxidative pathway and are not available for biosynthetic processes. It appears likely, therefore, that intracellular TAG-derived fatty acids which enter the oxidative pathway exist in a different compartment from those that are directed towards synthesis.

Glucose phosphorylation is essential for the turnover of neutral lipid and the second stage assembly of triacylglycerol-rich ApoB-containing lipoproteins in primary hepatocyte cultures.

Primary hepatocytes cultured in a medium supplemented with amino acids and lipogenic substrates responded to increased extracellular glucose by increasing the secretion of VLDL apoB. This effect was accompanied by an increased secretion of VLDL triacylglycerol (TAG) derived from endogenous stores. Glucose also stimulated intracellular TAG mobilization via the TAG lipolysis/esterification cycle. All these effects were abolished in the presence of mannoheptulose (MH), an inhibitor of glucose phosphorylation. Glucose also gave rise to a modest (50% to 60%) increase in the incorporation of 35S methionine into newly synthesized apoB (P<0.05) and to a doubling of newly-synthesized apoB secretion as VLDL (P<0. 05). The magnitude of these effects was similar for apoB-48 and for apoB-100. MH inhibited apoB-48 and apoB-100 synthesis and VLDL secretion at all glucose concentrations. The effects of glucose and MH on the secretion of newly-synthesized apoB-48 or apoB-100 as small dense particles were less pronounced. Glucose had no effects on the posttranslational degradation of newly-synthesized apoB-100 or apoB-48. However, this process was significantly enhanced by MH. The results suggest that glucose stimulates TAG synthesis, turnover, and output as VLDL. These effects are associated with an increased VLDL output of apoB mediated mainly by an increase in the net synthesis of both apoB-48 and apoB-100. All these changes are prevented by interference with glucose phosphorylation. Output of small, dense, apoB-containing particles is relatively unaffected by the glucose and MH-induced changes in TAG synthesis and lipolysis, an observation which suggests that only the bulk lipid addition step of VLDL assembly is affected by changes in glucose metabolism.

The intracellular triacylglycerol/fatty acid cycle: a comparison of its activity in hepatocytes which secrete exclusively apolipoprotein (apo) B100 very-low-density lipoprotein (VLDL) and in those which secrete predominantly apoB48 VLDL.

Hamster hepatocytes, like human hepatocytes, secrete triacylglycerol (TAG) as very-low-density lipoprotein (VLDL) in association with apolipoprotein (apo) B100, whereas in the rat, TAG is secreted predominantly in association with apoB48. Nevertheless, in hepatocytes from both species, a minimum of between 60% and 70% [69. 1+/-1.4% (hamster), 60.6+/-2.5% (rat)] of the VLDL TAG was secreted following lipolysis and re-esterification of intracellular TAG. The fractional rates of hepatocellular TAG turnover (lipolysis and re-esterification) were similar in both species [1.83+/-0.28 pools/24 h (hamster), 1.39+/-0.23 pools/24 h (rat)]. Comparison of the relative changes in the 3H and 14C specific radioactivities of the VLDL and cellular TAG, pre-labelled with [3H]glycerol and [4C]oleate, suggested that fatty acids released by lipolysis either were recruited directly into a VLDL assembly pool or were recycled to the cellular pool following re-esterification. Recycling in the hamster was somewhat greater than in the rat (66.1+/-5.7% versus 53. 7+/-4.8% of TAG lipolysed respectively). Similarly, a larger proportion of newly synthesized TAG was retained within the cell, rather than secreted as VLDL, in the hamster compared with the rat (37.9+/-2.8% versus 20+/-3.8%, P<0.01). These factors may have contributed to the somewhat lower rate of VLDL TAG secretion in the hamster hepatocytes compared with those from the rat (43.3+/-4.2 versus 96.4+/-3.4 microg/24 h per mg of cell protein). Rat hepatocytes were more sensitive to inhibition of VLDL secretion by insulin than were those from hamster. In neither case did insulin affect total or fractional TAG turnover. The results suggest that assembly of both apoB100 VLDL and apoB48 VLDL is associated with efficient intracellular TAG lipolysis.

The female athlete.

Women's participation in sporting activities is now diverse with new opportunities arising yearly. As a result, care of the the female athlete's unique medical concerns has become an important challenge and issue to the primary care physician. The major focus when caring for the female athlete should be the diagnosis and treatment of the female athlete triad. The components of the triad--disordered eating, amenorrhea, and osteoporosis--can have serious implications for the health of the female athlete. Appropriate prevention and screening methods for early diagnosis of the female athlete triad require future study and improvement. Healthy pregnant, postpartum, and breastfeeding women can continue to maintain physical activity. Musculoskeletal injuries from sports are, in general, not gender specific but are more often sport specific. One exception is the increased prevalence of anterior cruciate ligament injuries occurring in women soccer and basketball players. The exact cause of this is unknown but is continuing to be investigated.

Origin of hepatic very-low-density lipoprotein triacylglycerol: the contribution of cellular phospholipid.

When rat hepatocytes were cultured for 24 h in the absence of exogenous fatty acid, the amount of very-low-density lipoprotein (VLDL) triacylglycerol (TAG) secreted (114 +/- 14 micrograms/mg of cell protein) could not be accounted for by the mass of TAG lost from the cells (29 +/- 6.1 micrograms/mg of cell protein) during this period (n = 12). Of the balance (85 +/- 14 micrograms/mg; 94 +/- 15 nmol/mg), a maximum of only 37 nmol/mg of cell protein of TAG could be accounted for by fatty acids synthesized de novo. When labelled exogenous oleate (initial concentration, 0.75 nM) was present in the culture medium, the net gain in cellular plus VLDL TAG (253 +/- 38 micrograms/mg of cell protein per 24 h) was greater than that contributed by the exogenous fatty acid (155 +/- 18.2 micrograms/mg of cell protein, n = 5). Again, the balance (98.8 +/- 18.2 micrograms/mg of cell protein per 24 h) was too great to be accounted for by fatty acid synthesis de novo. In experiments in which cellular glycerolipids were prelabelled with [9, 10(n)-3H]oleic acid, following removal of the labelled fatty acid, there was a net increase in labelled cellular plus VLDL TAG over the next 24 h. That cellular phospholipids are the source of a substantial part of the excess TAG synthesized is supported by the following evidence. (1) The loss of prelabelled cellular phospholipid during culture was greater than could be accounted for by secretion into the medium. (2) During culture of cells prelabelled with 1,2-di-[l-14C]palmitoyl phosphatidylcholine, a substantial amount of label was secreted as VLDL TAG. (3) In pulse-chase experiments, the kinetics of labelled phospholipid turnover were consistent with conversion into a non-phospholipid pool. The enzymology involved in the transfer of phospholipid fatty acids into TAG is probably complex, but the present results suggest that this pathway may represent an important route by which extracellular fatty acids are channelled into VLDL TAG.

Selective recruitment of ApoB-48 for the assembly of VLDL in rat triacylglycerol-enriched hepatocytes.

Primary rat hepatocyte cultures were enriched in cellular triacylglycerol (TAG) by exposure to extracellular oleate for 3 days. Control cells were cultured for the same time without oleate. The large increase in TAG secretion into the medium of TAG-enriched cells during the final 24 hours (225 +/- 30 versus 40 +/- 10 micrograms/mg cell protein [control cells], P < .01) was not accompanied by a similar change in apolipoprotein B (apoB) secretion (4.22 +/- 0.94 versus 3.72 +/- 0.75 micrograms/mg per 24 hours, respectively). Instead, TAG-enriched cells recruited a larger proportion of apoB for the synthesis of very low density lipoprotein (VLDL), the secretion of which was substantially higher under these circumstances (1.46 +/- 0.39 versus 0.34 +/- 0.06 microgram apoB per milligram cell protein per 24 hours, P < .05). The increase in VLDL assembly was accompanied by a selective 2.5-fold increase (P < .05) in the specific recruitment of apoB-48. There was no significant increase in the amount of apoB-100, which appeared in the VLDL fraction when cells were enriched with TAG. Under these circumstances there was an increase in net cellular synthesis of apoB-48 (5524 +/- 667 versus 2505 +/- 598 disintegrations per minute per milligram protein per hour, P < .05). The net cellular synthesis of apoB-100 was unchanged compared with that observed in control cell cultures (1548 +/- 237 versus 2000 +/- 897 dpm/ mg per hour, respectively). A large proportion of the total secreted apoB was associated with small particles of density higher than VLDL, even when VLDL output was maximally stimulated, suggesting that apoB was oversecreted and in excess of the cells' requirement to transport TAG.

Pharmacological treatment of psychiatric disorders in children and adolescents: focus on guidelines for the primary care practitioner.

This article is a practical review of the current psychopharmacological agents used in the treatment of child and adolescent psychiatric disorders. Psychostimulants such as methylphenidate, dexamphetamine and pemoline are effective in the control of symptoms associated with attention deficit hyperactivity disorder. The controlled release preparations and the adjunctive use of clonidine are helpful to extend stimulant effects and control adverse effects. Tricyclic antidepressants are helpful in individual cases of child and adolescent depression, but adverse effects may limit their use. Clomipramine has been found to be effective for childhood obsessive-compulsive disorder. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) appear to be safer for depression and are also useful in obsessive-compulsive disorder. Buspirone is effective for the treatment of anxiety disorders in children. Newer atypical antipsychotics such as risperidone may have less limiting adverse effects than older antipsychotics in the treatment of psychosis and severe behaviour disorders, but the physician must be vigilant for the emergence of tardive dyskinesia. Drug treatment in children and adolescents must take into account the child's environmental influences and be part of an overall treatment plan where individual, familial and cultural issues are addressed.

Chronic exogenous hyperinsulinaemia does not modify the acute inhibitory effect of insulin on the secretion of very-low-density lipoprotein triacylglycerol and apolipoprotein B in primary cultures of rat hepatocytes.

Male Wistar rats were fitted with subcutaneous osmotic mini-pumps that delivered insulin at a constant rate of 0.20 i.u./h for 7 days. This treatment raised the plasma insulin concentration from 31 +/- 4 to 201 +/- 64 micro-i.u./ml. Hepatocytes prepared from the hyperinsulinaemic animals secreted very-low-density lipoprotein (VLDL) triacylglycerol (TAG) at a higher rate (172 +/- 21 microgram per 24 h per mg cell protein) than did those from sham-operated controls (109 +/- 12 microgram per 24 h per mg) (P<0.05). However, chronic exogenous hyperinsulinaemia had no stimulatory effect on the secretion of VLDL apolipoprotein B (apoB) in derived hepatocytes compared with those from the sham-operated controls (2.32 +/- 0.38 compared with 3.09 +/- 0.40 microgram per 24 h per mg). Hepatocytes from the hyperinsulinaemic rats thus secreted larger VLDL particles as evidenced by the increased TAG:apoB ratio (78.4 +/- 13.1 compared with 38.4 +/- 7.6; P<0.05). In hepatocytes from the hyperinsulinaemic rats a larger proportion of the newly synthesized TAG was secreted as VLDL. Hepatocytes from the hyperinsulinaemic and the sham-operated control animals were equally sensitive to the inhibitory effect of insulin added in vitro on the secretion of VLDL TAG. Insulin added in vitro to the culture medium of hepatocytes from hyperinsulinaemic animals significantly decreased the TAG:apoB ratio of the secreted VLDL. This change did not occur in hepatocytes from sham-operated rats. These results suggest that, in vivo, chronic hyperinsulinaemia is not in itself sufficient to desensitize the liver to the acute inhibitory effect of insulin on the secretion of VLDL.