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H J Wolf

Publications and source records attributed to H J Wolf.

At least 19 recordsLinked to original sources
PubMed2002

Polar expression and phosphorylation of human leptin receptor isoforms in paired, syncytial, microvillous and basal membranes from human term placenta.

The hormone leptin (OB) and its receptor (OB-R) are key homeostatic regulators of mammalian body weight. Two predominant isoforms of OB-R are expressed by alternative splicing: the long form, OB-RL, with full signalling capacity is highly expressed in the hypothalamus and the short, signalling-defective form, OB-Rs, is ubiquitously expressed. In a previous study we detected expression of OB-RL and OB-Rs in human syncytiotrophoblast cells using in situ hybridization and immunohistochemistry (Bodner et al., 1999). The aim of this study was to investigate leptin receptor isoform expression and phosphorylation in paired, syncytial, microvillous and basal membranes from human term placenta by Western blot analysis. Both the OB-RL and the OB-Rs isoforms were detected in the syncytial membrane preparations. The OB-RL isoform was observed exclusively in microvillous membranes, whereas the OB-Rs isoform was found in both microvillous and basal membrane preparations. No significant differences were observed between syncytial membranes from normal and type 1 diabetic pregnancies. To test the phosphorylation capacity of the OB-R isoforms, microvillous and basal membrane vesicles loaded with ATP were stimulated with leptin and the phosphorylation status of the OB-R at the tyrosine 985 (Y985) was determined. A single band at the molecular weight corresponding to the molecular weight of the OB-RL isoform was detected exclusively in the ATP-loaded microvillous vesicles. We conclude that the long form OB-RL is expressed exclusively in the microvillous membrane of the syncytiotrophoblast and is capable of being phosphorylated, suggesting that it has signal transduction capacity.

Adolescent↗
PubMed2001

Lipoprotein profile and cholesteryl ester transfer protein in neonates.

Undernourishment in utero appears to be associated with persisting changes in the metabolic, endocrine, and immune functions. In this study, we determined the influence of birth weight on the lipoprotein profile and cholesteryl ester transfer protein (CETP), which promotes a proatherogenic lipoprotein profile in plasma by determining the chemical, physical, and biologic properties of the respective lipoprotein particles. Triglyceride (TG) concentrations were highest and high-density lipoprotein (HDL)(2)-cholesterol levels were lowest in small for gestational age (SGA) neonates. CETP-mass was determined by enzyme-linked immunosorbent assay (ELISA) and CETP-activity by using exogenous lipoproteins. Cholesteryl ester transfer was determined as transfer of radiolabeled cholesteryl esters (CE) from HDL to apolipoprotein B-containing lipoproteins. CETP mass was lowest and cholesteryl ester transfer was highest in SGA neonates. CETP-activity did not differ among the neonates. Our results suggest that increased and decreased nourishment in utero affects the lipoprotein profile and CETP in neonates. High TG and low HDL(2) levels in SGA neonates might result from increased cholesteryl ester transfer and, may in part, explain the increased risk of coronary heart disease (CHD) of small for gestational age neonates in later life.

Adult↗
PubMed2000

Fetal leptin and insulin levels only correlate inlarge-for-gestational age infants.

OBJECTIVE: To determine whether fetal leptin levels correlate with fetal weight and whether such correlation is direct or indirect via insulin or human placental lactogen (hPL), respectively. DESIGN: Cross-sectional study of offspring at term (n=175) with over-representation of large-for-gestational age (LGA; n=70) and small-for-gestational age (SGA; n=23) cases in a population of Caucasian women with no pregnancy pathology. METHODS: Fetal cord blood was collected after delivery. In several cases (n=62) paired mother-fetus blood samples were obtained. Leptin, insulin and hPL levels were measured by RIA. Anthropometric data (birth weight, body mass index, placental weight) were recorded. RESULTS AND CONCLUSIONS: Maternal insulin, hPL and leptin levels were higher than fetal concentrations. Cord blood leptin levels positively correlated with the anthropometric data with stronger correlations in female (0.54<r<0.66) than in male (0.32<r<0.39) neonates. Cord blood leptin levels did not differ between appropriate-for-gestational age (AGA; n=82) and SGA (n=23) neonates, but were higher (P<0.001) by 83% in LGA (n=70) than in AGA neonates. Among the different weight classes the correlations between fetal leptin and anthropometric data were only observed in LGAs, but not in AGAs or SGAs. Fetal, but not maternal, leptin levels strongly correlated with fetal insulin (r=0.56; P<0.001). After accounting for this close relationship insulin could no longer be used to predict birth weight (r=0.15, P=0.051). We suggest that the correlation of cord blood insulin with neonatal weight in LGAs is, in addition to insulin's direct anabolic action, indirectly mediated via leptin. It is hypothesized that fetal insulin stimulates fetal adipocyte leptin production.

Birth Weight↗
PubMed1999

Leptin receptor in human term placenta: in situ hybridization and immunohistochemical localization.

In the present study, we investigated the expression and localization of leptin receptors in human term placentae. On human term placenta tissue slices, digoxigenin-UTP labelled RNA-probe detected the long form of the leptin receptor ObR(L)mRNA in syncytiotrophoblasts of the villi, whereas the haematological subtype of the leptin receptor ObR/B219.1 was detected in blood cells of the intervillous space and fetal vessels. Immunohistochemistry, with two polyclonal antibodies to the N-terminus recognizing ObR(L)and ObR(S)of the leptin receptors and one to the C-terminus recognizing the long form of the leptin receptor ObR(L), localized leptin receptor protein at the apical membrane of the syncytiotrophoblasts. Our results show that the long form of the leptin receptor ObR(L)is expressed in human term placentae. We localized the long form of leptin receptor mRNA to the cytoplasm of syncytiotrophoblasts and leptin receptor proteins in human term placentae to the apical membrane of syncytiotrophoblasts. We conclude that in term placentae, leptin could mediate a growth promoting effect in the fetoplacental unit through the long form of the leptin receptor localized in the syncytiotrophoblasts. In contrast, the haematological subtype of the leptin receptor is not expressed in placental cells, but solely by blood cells in the intervillous space and fetal vessels.

Carrier Proteins↗
PubMed1998

[Leptin--an interim evaluation].

The discovery of leptin, the product of the obese (ob)-gene, has broadened the horizons of research on energy balance. This hormone, produced and secreted by adipose tissue and some placental cells, finds its way to the hypothalamus, where it binds to the leptin receptors and signals satiety through the neuroendocrine axis. The fact that adipose tissue is not merely a storage depot, but also an important endocrine tissue, has revived the interest in the "lipostatic" theory of body fat regulation and has initiated many research efforts in the field of obesity, anorexia nervosa, bulimia, reproduction and haematology.

Adipose Tissue↗
PubMed1997

Lipoprotein lipase, LDL receptors and apo-lipoproteins in human fetal membranes at term.

Ultrastructurally, all cells of human fetal membranes strongly exhibit a large amount of lipid deposits throughout pregnancy. Their origin and function is still unknown. The aim of this study was to investigate the localization of key components of lipid metabolism in this tissue. Using immunohistochemical techniques, the distribution of lipoprotein lipase (LPL), low density lipoprotein receptors (LDL receptors), and apo-lipoprotein B and E was investigated in 20 human fetal membranes at term. In addition, electron microscopy was used to study the intracellular localization of lipoprotein-sized particles. Amnionic epithelium and trophoblast cells reacted strongly for LPL. LDL receptors and apo-lipoproteins were present in amnionic epithelium and fibroblasts of the amnion. In none of the investigated cells were lipoprotein-sized particles identified. Similar results were obtained in all 20 cases. The findings indicate that lipoprotein from the amniotic fluid or from the maternal circulation may serve as substrate for lipids in human fetal membranes.

Amnion↗
PubMed1997

Dopamine and intestinal mucosal tissue oxygenation in a porcine model of haemorrhage.

Haemorrhage is associated with intestinal mucosal hypoxia and impaired gut barrier function. Dopamine increases oxygen delivery to the intestinal mucosa and may thus counteract haemorrhage-induced mucosal hypoxia. Jejunal mucosal tissue oxygen tension (mucosal PO2) and jejunal oxygen saturation of mucosal microvascular haemoglobin (mucosal HbO2) were measured in 14 anaesthetized pigs. Seven animals served as controls (group C) and seven received continuous infusion of dopamine 16 micrograms kg-1 min-1 (group D) while 45% of blood volume was removed in three equal increments. Resuscitation was performed using shed blood and fluid. Mean arterial pressure and systemic oxygen delivery decreasing significantly during haemorrhage and returned to baseline after resuscitation in both groups. Mucosal PO2 decreased from 4.4 to 1.7 kPa after haemorrhage (P < 0.01) and further to 1.5 kPa after resuscitation (P < 0.01) in group C whereas group D showed an increase from 3.9 to 5.9 kPa after the start of the dopamine infusion (P < 0.05), but no significant difference from baseline after haemorrhage (2.3 kPa) (ns) or resuscitation (3.1 kPa) (ns). Mucosal HbO2 decreased from 52 to 32% after haemorrhage (P < 0.05) and increased to near baseline (37%) (ns) after resuscitation in group C whereas group D showed no significant changes from baseline (54%) throughout the experiment. Comparison between groups showed higher mucosal PO2 and HbO2 values for group D animals after the start of the dopamine infusion (P < 0.05 each), after the first two steps of haemorrhage (P < 0.01 each) and after resuscitation (P < 0.05 each). We conclude that i.v. dopamine 16 micrograms kg-1 min-1 improved tissue oxygenation of the small intestinal mucosa during moderate haemorrhage and subsequent resuscitation.

Animals↗
PubMed1996

Effects of short-term endotoxemia and dopamine on mucosal oxygenation in porcine jejunum.

Effects of Escherichia coli lipopolysaccharide (2 micrograms.kg-1.20 min-1; LPS), given systemically (S) or via superior mesenteric artery (M), and consecutive dopamine infusion (16 micrograms.kg-1.20 min-1) on jejunal mucosal tissue O2 tension (PO2muc) and serosal tissue O2 tension (PO2ser; Clark-type surface electrodes) and jejunal mucosal microvascular hemoglobin O2 saturation (HbO2muc; tissue reflectance spectrophotometry) were investigated in a hemodynamically stable pig model. Twenty-one pigs were anesthetized, paralyzed, and mechanically ventilated. After laparotomy, a mesenteric venous catheter was inserted and a jejunal antimesenteric enterotomy performed. LPS-infused animals developed similar degrees of pulmonary hypertension. No differences in cardiac output and mean arterial blood pressure between groups were found. PO2muc and HbO2muc were significantly lower in M animals compared with control (C) [210 min; PO2muc: 7.12 +/- 1.81 (M), 19.01 +/- 3.12 mmHg (C); HbO2muc: 28.78 +/- 3.36 (M), 49.09 +/- 3.84% (C)], whereas S animals ranged in between (PO2muc: 13.36 +/- 2.2 mmHg; HbO2muc: 40.68 +/- 4.43%). Of measured PO2muc values, 12.6 (C), 20.6 (S), and 46.3% (M) ranged from 0 to 5 mmHg. PO2ser was lower in LPS animals compared with control [59.43 +/- 5.4 (C), 45.00 +/- 6.12 (S), 47.33 +/- 4.34 (M) mmHg]. Dopamine increased PO2muc and HbO2muc to similar absolute values and significantly decreased frequency of PO2muc (0-5 mmHg) in M animals. We conclude that LPS impairs mucosal tissue oxygenation independently of systemic hemodynamics. Mucosal microvascular dysfunction depends on regional LPS concentrations. Under conditions of compromised tissue oxygenation, dopamine significantly improves PO2muc and HbO2muc.

Animals↗
PubMed1996

Idiotype vaccination strategies against a murine B-cell lymphoma: dendritic cells loaded with idiotype and bispecific idiotype x anti-class II antibodies can protect against tumor growth.

Three strategies were used to evaluate 38C13 B-cell lymphoma-specific idiotype immunization to protect against subsequent lymphoma challenge in C3H/He mice. It was observed that tumor-specific immunity could be induced by immunization with (i) KLH-conjugated 38C13 B-cell lymphoma idiotype in complete Freund's adjuvants (survival rate 80%), (ii) dendritic cells pulsed in vitro with native idiotype protein (survival rate 80%), and (iii) bispecific antibodies composed of B-lymphoma-related idiotype and an MHC class II binding moiety (survival rate 40%). Presentation of idiotype determinants by dendritic cells or bispecific antibody resulted in lymphoma-specific immunity and obviated the requirement for carrier protein or adjuvant. Moreover, primed dendritic cells induced predominant development of a tumor-specific T-cell response. Each of these immunization strategies resulted in long-term survival without the emergence of idiotype variants or the induction of tumor dormancy.

Animals↗
PubMed1993

Immunohistochemical localization of glucose transporters and insulin receptors in human fetal membranes at term.

The localization has been investigated of the isoforms GLUT1, GLUT3 and GLUT4 of glucose transporter proteins as well as of insulin receptors. Fetal membranes (n = 10) were examined by immunohistochemical methods at the light and electron microscopic levels using mono- and polyclonal antibodies. In all amnion epithelial cells, GLUT1 and GLUT3 antibodies were bound to the apical membrane. Very rarely the GLUT1 antibody also immunostained the basolateral membrane and reacted weakly with the endomembrane system and membranes of the lateral cell protrusions. Fibroblasts reacted with the antibodies against GLUT1, GLUT4 and insulin receptor, whereas they were labelled only in one case with GLUT3 antibody. Cytotrophoblast cells were only stained with antibodies against GLUT1 and GLUT3. Antibodies against GLUT4 only reacted with fibroblasts in the membranes. On amnion epithelial cells, weak immunoreactivity with insulin receptor antibodies was detected only at the electron microscopic level. The data indicate: (1) GLUT1 is located on all cells of the amnion, whereas GLUT3 is present in detectable amounts only on amnion epithelial cells and cytotrophoblast; (2) GLUT1 and GLUT3 on amnion epithelial cells are predominantly located on the apical surface; (3) GLUT4 and insulin receptors are not regularly expressed. We suggest that amnion epithelial cells cover their basal glucose requirements from the amniotic fluid and not from the maternal circulation.

Amnion↗
PubMed1991

Immunocytochemical analysis of the cytoskeleton of the human amniotic epithelium.

The amniotic epithelium constitutes a diffusion barrier controlling the passage of solutes and water between the amniotic cavity and maternal circulation. With the present immunocytochemical approach, we have shown that several major components of the cyto-skeleton, i.e., actin, alpha-actinin, spectrin and ezrin, are preferentially associated with the apical and lateral cell surfaces of the human amniotic epithelium. Keratins are distributed throughout the entire cytoplasm, whereas vimentin mainly forms a perinuclear scaffold. These findings indicate a role of the various components of the cytoskeleton in the structural integrity and modulation of cell shape and junctional permeability.

Actinin↗
PubMed1991

[Histochemical study of carbohydrate metabolism in fetal membranes].

By means of histochemical methods, we investigated the location of carbohydrates and the carbohydrate metabolism in the fetal membranes. It was shown that the often extremely intense vacuolisation of the trophoblast cells is based on the excessive accumulation of glycogen. Perhaps the reason, that glycogen could not be shown up to now, is that it lies in an undetectable state. From our enzyme histochemical results, we conclude that out of glycogen, lipids, phospholipids, also mucopolysaccharides and collagen for the extracellular matrix are synthetized. Furthermore we assumed, that glycogen is partly depolymerized and transported towards the amniotic epithelial with a liquid flow. After uptake by the fibroblasts, it is used for the further production of extracellular matrix. The carbohydrate component of glycoproteins and proteoglycans were classified by the use of lectin-binding-studies. The amniotic epithelial cell does not only release glycoproteins and proteoglycans on the apical cell surface but also into the intercellular space. These substances are probably related to the intercellular liquid flow. 3H-labelled glucose passed through this intercellular space and transcellular through the amniotic epithelium.

Alcian Blue↗
PubMed1990

Early intervention in low back disability among coal miners in West Virginia: negative findings.

A major issue in the field of workers' compensation is cost containment, not only of medical costs, but of extended disability costs as well. For a 9-month period in 1985 to 1986, the West Virginia Workers' Compensation Fund tested an early intervention case management approach begun within 2 weeks after injury and found it not to be cost effective. In a controlled study of 284 reported back injuries among underground coal miners, medical costs increased with the case management intervention, although only to the extent of the added costs of the intervention, and disability costs and time lost from work did not decrease. Permanent partial disability awards, litigation rates, number of hospitalizations, and return to work were similar between both the experimental and control groups. Regression analyses of 25 factors identified factors most highly predictive of disability and medical costs, but in predicting extended disability, although the factors were 100% sensitive, they were only 43.6% specific. The case management approach was insufficient to prevent extended disability or to lower medical costs.

Absenteeism↗
PubMed1980

Ultrastructure of methanotrophic yeasts.

The cellular structure of two yeast strains capable of growth on methane was investigated by electron microscopy. Microbodies were observed in cells of Sporobolomyces roseus strain Y and Rhodotorula glutinis strain CY when grown on methane but rarely when grown on glucose. The size of the microbodies and the number observed per cell in a thin section did not increase with culture age. No crystalline organization was observed within these organelles. Similar microbodies were also observed in cells of R. glutinis CY grown on hexadecane. The plasma membranes of both methane and hexadecane-grown cells exhibited increased invagination compared to that of glucose-grown cells. Catalase activity was detected in the microbodies of alkane-grown cells by using 3,3'-diaminobenzidine as a cytochemical stain. The data presented suggest that microbodies, and the catalase contained within them, play a role in eucaryotic methane metabolism.

Alkanes↗