Oval-shaped cornea, lens duplication, and optic nerve hypoplasia associated with myelomeningocele.

Oval-shaped cornea associated with true lens duplication and separate capsules is a rare anomaly. It can occur as an isolated finding(1,2) or be associated with other ocular and facial maldevelopments.(3-5) We report a novel association of an hourglass cornea, lens duplication, and optic nerve hypoplasia with myelomeningocele in a male infant.

Metabolic heterogeneity of hepatocytes across the liver acinus.

Periportal hepatocytes around the afferent vessels and perivenous hepatocytes around the efferent vessels of the liver acinus exhibit different metabolic capacities and subcellular structures. This observation led to the concept of the metabolic zonation of the liver acinus. Oxidative energy metabolism, gluconeogenesis, urea synthesis, bile formation and protective metabolism are catalyzed mainly in the periportal zone; glycolysis linked to liponeogenesis, glutamine synthesis and xenobiotic metabolism are predominant in the perivenous zone. This zonation is dynamic rather than static. Zonation develops gradually, depending on perinatal changes of the hepatic circulation and on postnatal alterations of the supply with energy substrates. Zonation also is modulated during puberty. Moreover, adaptation to longer-lasting physiological and pathological alterations occurs as observed during starvation and refeeding, diabetes and regeneration after partial hepatectomy or zonal necrosis. Periportal to perivenous gradients of oxygen, hormones and metabolites, as well as zonal differences in the hepatic innervation, seem to be responsible for the heterogeneous gene expression within the liver acinus.

Effects of vanadate on 6-phosphofructo 2-kinase activity and fructose 2,6-bisphosphate levels in cultured rat hepatocytes.

The presence of vanadate in primary cultures of rat hepatocytes produced a significant increase in the concentration of fructose 2,6-bisphosphate and in the activity of 6-phosphofructo 2-kinase. Compared with insulin, vanadate had a more potent action on the metabolite increase, but a similar effect on the 6-phosphofructo 2-kinase activity. Both the insulin- and the vanadate-dependent enhancements of 6-phosphofructo 2-kinase were inhibited by cycloheximide which specifically blocks protein synthesis on the translational level, suggesting that the increase of the enzyme activity was due to induction rather than to a change in the catalytic activity.

Methods for the study of liver cell heterogeneity.

A large number of histological, histochemical and biochemical techniques are available for studying liver cell heterogeneity. Structural differences are recognized by morphometric analyses of electron micrographs. The zonal heterogeneity of enzyme activities can be demonstrated by histochemistry and more precisely by ultramicrobiochemical assays in microdissected periportal and perivenous tissue. Immunohistochemistry is useful for quantifying and localizing proteins, especially isoenzymes, without depending on their biological activity. The zonal quantification of specific mRNA can be achieved by in situ hybridization. The different structural and enzymic equipment of periportal and perivenous tissue found by these techniques has led to the concept of metabolic zonation. This hypothesis can be confirmed by determination of metabolic rates in perfused liver after selective zonal damage, in separated periportal and perivenous hepatocytes as well as in periportal and perivenous tissue of perfused liver by non-invasive techniques.

Effect of the alpha-glucosidase inhibitor N-hydroxyethyl-1-deoxynojirimycin (Bay m 1099) on the biosynthesis of liver secretory glycoproteins.

The effect of the alpha-glucosidase inhibitor N-hydroxyethyl-1-deoxynojirimycin (Bay m 1099) on the glycosylation and secretion of alpha 1-antitrypsin (three complex type oligosaccharide chains) and of alpha 1-acid glycoprotein (six complex type oligosaccharide chains) was studied in rat hepatocyte primary cultures. In the presence of 4 mM Bay m 1099 the processing of high-mannose to complex type oligosaccharides was partially inhibited leading to the secretion of alpha 1-antitrypsin and alpha 1-acid glycoprotein carrying a mixture of both high-mannose and complex type oligosaccharides. The major part of alpha 1-antitrypsin secreted by Bay m 1099 treated cells still carried two complex type oligosaccharide chains, the majority of alpha 1-acid glycoprotein carried three to five. Despite its effects on protein glycosylation Bay m 1099 did not lead to pronounced changes in the synthesis or secretion of alpha 1-antitrypsin, alpha 1-acid glycoprotein or albumin. At concentrations of Bay m 1099 lower than 0.5 mM no inhibitory effect on oligosaccharide trimming could be observed. After removal of Bay m 1099 from hepatocytes its inhibitory effect on protein glycosylation was immediately reversible.

Increase in surface expression of transferrin receptors on cultured hepatocytes of adult rats in response to iron deficiency.

The effect of changes in cellular iron metabolism on the surface expression of transferrin receptors (TfR) was examined in primary cultures of hepatocytes from adult rats. Untreated control hepatocytes exhibited a single class of high affinity receptors for transferrin (KD = 40 nM), with approximately 17,000-18,000 receptors per cell. Following 24 h of treatment with the iron chelator, desferrioxamine, or with succinylacetone, an inhibitor of heme synthesis, the number of TfR at the cell surface was increased severalfold, with no significant change in receptor affinity (KD) for transferrin. When combined, the enhancing effects of the two agents were additive. Inhibition of protein synthesis by cycloheximide abolished the increase in TfR expression mediated by either agent. Hemin decreased surface TfR expression and counteracted the enhancing effects of desferrioxamine or succinylacetone on TfR expression. These results indicate that, under the culture conditions employed, 1) iron deficiency induces an increase in surface TfR and 2) modulation of the receptor population is mainly dependent on de novo synthesis of TfR.

Meta-analysis of correlates of provider behavior in medical encounters.

This article summarizes the results of 41 independent studies containing correlates of objectively measured provider behaviors in medical encounters. Provider behaviors were grouped a priori into the process categories of information giving, questions, competence, partnership building, and socioemotional behavior. Total amount of communication was also included. All correlations between variables within these categories and external variables (patient outcome variables or patient and provider background variables) were extracted. The most frequently occurring outcome variables were satisfaction, recall, and compliance, and the most frequently occurring background variables were the patient's gender, age, and social class. Average correlations and combined significance levels were calculated for each combination of process category and external variable. Results showed significant relations of small to moderate average magnitude between these external variables and almost all of the provider behavior categories. A theory of provider-patient reciprocation is proposed to account for the pattern of results.

Task versus socioemotional behaviors in physicians.

This paper investigates associations among physicians' task-oriented and socioemotional behaviors during the medical encounter. The study is an analogue, using as source data the audiotapes and transcripts of two standardized patient cases presented by trained patient simulators to 43 primary care practitioners. Transcripts were scored for physician proficiency and were content-analyzed to assess the process of communication and information content. Physicians' speech errors were counted, and vocal affect ratings were made of filtered audiotape excerpts. Physician communications reflected by these measures were classified as task-oriented or socioemotional. Findings indicated: 1) Most aspects of physician style were reliable across visits. 2) Physicians adopted either a patient-oriented or a physician-oriented approach to task performance, as characterized by giving information and counseling versus giving directions and asking questions, respectively. 3) Verbal and nonverbal socioemotional measures were not related. 4) Physicians tended to adopt either a style characterized by information-giving and proficiency or a social orientation with patients. 5) Physicians who were more medically informative had more interested and anxious voices compared with the less informative physicians. Thus, although the more medically informative physicians spent less time making socioemotional utterances, they had a voice quality that may compensate for that neglect.

Relations between physicians' behaviors and analogue patients' satisfaction, recall, and impressions.

This paper investigates associations between physicians' task-oriented and socioemotional behaviors, on the one hand, and analogue patients' satisfaction, recall of information, and global impressions. The study is based on role-playing subjects' responses to interactions between physicians and simulated patients. Audiotapes of two standardized patient cases presented by trained patient simulators to 43 primary care physicians were rated by role-playing patients (N = 258), and electronically filtered excerpts from the encounters were rated for vocal affect by 37 independent judges. Content analysis was made of the visits' transcripts to assess interaction process and to identify all medical information communicated. Finally, speech error rate was calculated from a combination of audiotape and transcript. Findings revealed that role-playing patients clearly distinguished task from socioemotional behaviors of the physicians, and a consistent pattern of association emerged between physicians' task behaviors and role-playing patients' satisfaction, recall, and impressions. Within the task domain, patient-centered skills (i.e., giving information and counseling) were consistently related to patient effects in a positive direction, but physician-centered behaviors (i.e., giving directions and asking questions) demonstrated the opposite relationship. A negative pattern of association was also evident between physicians' socioemotional behaviors and patient effects.

Carbohydrate-dependent induction of fatty acid synthase in primary cultures of rat hepatocytes.

The glucose and insulin-dependent long-term regulation of fatty acid synthase was studied in primary cultures of hepatocytes from adult female rats. Under basic culture conditions, i.e. 5.5 mM glucose and 0.5 nM insulin, the enzyme activity was continuously decreased over 6 days. In the presence of 100 nM insulin this decrease was reduced but it was not prevented. Enhancement of glucose to 20 mM was followed by an increase of the enzyme activity; after 5 days of treatment the activity was three times higher than under basic culture conditions. The simultaneous presence of 20 mM glucose and of 100 nM insulin resulted in a much more pronounced increase of the activity; after 5 days of treatment the activity was eight times higher than under basic culture conditions. The enhancement was prevented by inhibition of glycolysis. This may indicate that the increase of fatty acid synthase was mediated by a metabolite of glucose rather than by glucose itself. The coordinate regulation of fatty acid synthase and of other lipogenic enzymes was specific as demonstrated by comparison with the activity of lactate dehydrogenase and with synthesis and degradation of cytosolic proteins. The enhancement of the enzyme protein, demonstrated by rocket immunoelectrophoresis, was due to an increase in the rate of enzyme synthesis by 600% as well as to a prolongation of the apparent half-life of the enzyme by 50% (45 h).

Partial characterization of intra- and extracellular forms of the glycoprotein hemopexin in liver cell culture and cell-free translation.

Primary cultures of rat hepatocytes produce extracellular and intracellular species of hemopexin. We examined the presence of high-mannose oligosaccharides and neuraminic acid residues in these species by comparing their electrophoretic mobility on SDS-PAGE before and after digestion by endoglycosidase H and neuraminidase. The predominant intracellular form was not susceptible to digestion by neuraminidase but was sensitive to endoglycosidase treatment, which digested it to a species with a molecular weight comparable to that of the sole hemopexin species produced by tunicamycin-treated hepatocytes and that produced by in vitro translation. By contrast, both the minor intracellular and the extracellular species of hemopexin were neuraminidase-, yet not endoglycosidase H-sensitive, and may be identical. It can be concluded that the intracellular precursor contains high-mannose type oligosaccharides which are processed to complex type oligosaccharides shortly before secretion of hemopexin.

Synthesis and secretion of hemopexin in primary cultures of rat hepatocytes. Demonstration of an intracellular precursor of hemopexin.

Secretion of hemopexin (20% carbohydrate) and its dependence on glycosylation was studied in primary rat hepatocyte cultures in comparison to the secretion of transferrin (5% carbohydrate). In pulse-chase experiments with [35S]methionine half of the labeled hemopexin was secreted in 30 min. By contrast, it took approximately 50 min for secretion of half of the transferrin. Tunicamycin treatment of cultures significantly delayed the secretion of hemopexin but not that of transferrin. During the pulse period a prominent intracellular precursor of hemopexin, smaller than the mature protein, was evident. It is concluded that the extent of glycosylation of a secretory protein is not necessarily a determinant of the transit time required for intracellular processing and secretion. In the case of hemopexin the glycosylation apparently facilitates the secretion although it is not an absolute prerequisite for the exocytosis of this protein.

Glucose-dependent induction of acetyl-CoA carboxylase in rat hepatocyte cultures.

The carbohydrate-dependent long-term regulation of acetyl-CoA carboxylase was studied in primary hepatocyte cultures from adult rats. (1) The enzyme activity was increased 2-fold either by elevation of the glucose concentration to 20mM or by enhancement of the insulin concentration to 0.1 microM. Simultaneous increases in glucose and insulin resulted in a 5-fold increase in the enzyme activity. (2) As shown by immunochemical titration, the enhancement of the enzyme activity was due to an increase in the enzyme protein. (3) Incorporation of [35S]methionine and immunoprecipitation of the enzyme revealed that the increase in enzyme protein was due to an increased rate of enzyme synthesis. The rate of enzyme degradation remained essentially unchanged. (4) The glucose- and insulin-dependent induction of acetyl-CoA carboxylase was prevented by the addition of alpha-amanitin (10 microM) or cordycepin (10 microM), indicating a transcriptional regulation of the enzyme level. (5) The parallel induction of acetyl-CoA carboxylase and of ATP citrate lyase indicates a co-ordinate long-term regulation of lipogenic enzymes.

Distribution of enzymes of fatty acid and ketone body metabolism in periportal and perivenous rat-liver tissue.

The zonal distribution of cytosolic acetyl-CoA carboxylase, mitochondrial 3-hydroxyacyl-CoA dehydrogenase and 3-hydroxybutyrate dehydrogenase was studied in microdissected liver tissue. In fed male and female rats the activity of the lipogenic enzyme acetyl-CoA carboxylase was 1.6-times higher in the perivenous than in the periportal zone of the liver acinus. 3-Hydroxybutyrate dehydrogenase, which is involved in the formation of the ketone body, 3-hydroxybutyrate, exhibited a similar distribution pattern with a 1.5-1.8-times higher activity in the perivenous than in the periportal zone. In contrast, the activity of 3-hydroxyacyl-CoA dehydrogenase, the third enzyme in beta-oxidation, was about equally distributed between the periportal and the perivenous zone of the liver acinus. The results indicate a predominance of lipogenesis in the perivenous, mainly glycolytic zone of the liver acinus. Furthermore, these data support the hypothesis that beta-oxidation supplies energy for basic and anabolic processes like gluconeogenesis in the periportal zone, while it provides acetyl-CoA for ketogenesis besides energy for basic needs in the perivenous zone.

Altered distribution of hexokinase and glucokinase between parenchymal and nonparenchymal cells of rat liver after methapyrilene intoxication.

The cell number as well as the hexokinase and glucokinase activity of liver parenchymal and nonparenchymal cells were studied in methapyrilene treated rats. The number of nonparenchymal cells was doubled after treatment with methapyrilene for two weeks while that of hepatocytes remained constant. The hexokinase activity was increased fourfold in the nonparenchymal cell fraction while it was unchanged in the parenchymal cells. The glucokinase activity was decreased in the hepatocytes to one third. Hence, the increased hexokinase activity was due to a proliferation of nonparenchymal cells rather than to a toxic dedifferentiation of hepatocytes.

Glucose- and insulin-independent induction of ATP citrate lyase in primary cultures of rat hepatocytes.

ATP citrate lyase, which is involved in the translocation of the lipogenic precursor acetyl-CoA from mitochondria to cytosol, was studied in primary cultures of hepatocytes from adult rats. After an initial decrease at the first day of culture the enzyme activity was nearly constant during the following days. It could be enhanced between 24h and 48 h in culture about 1.5-fold by elevation of the insulin concentration to 10-7mol/1.22-fold by elevation of the glucose concentration from 5 to 25 mmol/l and 3.5-fold by simultaneous elevation of insulin and glucose. The increase of activity was about linear with time for 24 h and could be blocked by cycloheximide, which inhibits protein synthesis at the translational level. Both observations suggest that the enhancement of activity was due to induction rather than to activation by interconversion. The glucose-dependent induction was furthermore evidenced by immunotitration which indicated a parallel increase of activity and enzyme protein.

Heterogeneous distribution of ATP citrate lyase in rat-liver parenchyma. Microradiochemical determination in microdissected periportal and perivenous liver tissue.

1. A radiochemical microtest was established for the determination of ATP citrate lyase in tissue samples of 0.2-1.0 micrograms dry weight. The specificity of this test system was guaranteed by its coenzyme A dependence as well as by inhibition of the activity measured in presence of a specific antibody. 2. Using this test system ATP citrate lyase activity was determined in microdissected periportal and perivenous liver tissue of fed, fasted and refed animals. The perivenous activity was 1.8-fold and 2.4-fold higher than the periportal one in fed male and female rats respectively. 3. The perivenous to periportal gradient was decreased during starvation-dependent reduction of the ATP citrate lyase activity. On the other hand it was not only restored but enhanced up to 2.8 after refeeding-dependent enhancement of the enzyme activity. 4. The predominance of the ATP citrate lyase activity in the perivenous, mainly glycolytic zone supports the hypothesis of the coordinate zonation of the carbohydrate and the lipid metabolism in the liver parenchyma.

Inversion of the metabolic zonation of rat liver parenchyma by methapyrilene treatment.

Treatment with the antihistaminic agent methapyrilene led to a decrease of glucose-6-phosphatase activity and to an increase of glucose phosphorylating activity in the periportal zone of the liver acinus. However, the glucogenic capacity was maintained by a compensatory elevation of glucose-6-phosphatase and simultaneous reduction of hexokinase and glucokinase in the perivenous zone. The normal metabolic zonation with a glucogenic periportal and a glycolytic perivenous zone was not abolished but inverted by these alterations.