Pharmacological studies on Puerariae flos III: protective effects of kakkalide on ethanol-induced lethality and acute hepatic injury in mice

Kakkalide, one of the major isoflavonoid components of Puerariae flos, has been investigated for its effect on ethanol-induced intoxication and on hepatic injury, including hyperglycaemia, in mice. Kakkalide reduced mortality associated with administration of ethanol. At doses of 100 and 200 mg kg-1 the effect of kakkalide was significant. The same dose of kakkalide prevented increased serum glutamic oxaloacetic transaminase and glutamic pyruvic transaminase activity. At a dose of 200 mg kg-1 it also counteracted ethanol-induced elevation of glucose levels. These results suggest that kakkalide might be useful for counteracting the effects of alcohol and might be effective for treating hepatic injury.

Different G proteins mediate somatostatin-induced inward rectifier K+ currents in murine brain and endocrine cells

1. Types of G proteins (G protein alpha-subunit subtypes) which mediate the activation of inward rectifier K+ currents by somatostatin (somatotrophin release-inhibiting factor, SRIF) were determined in cultured locus coeruleus neurones from newborn rats and in AtT-20 cells (a mouse pituitary cell line). 2. The whole-cell patch clamp technique was used together with injection of antibodies against pertussis toxin (PTX)-sensitive G protein alpha-subunits or with injection of antisense (or sense) oligonucleotides against these G proteins. 3. In locus coeruleus neurones, the SRIF-induced activation of inward rectifier K+ currents was inhibited by anti-G alpha i1/G alpha i2 antibody injection, but not by anti-G alpha i3 or by anti-G alpha o/G alpha i3 antibody injection, suggesting that the SRIF response is mediated through G alpha i1 and/or G alpha i2. 4. The SRIF-induced activation of the inward rectifier was suppressed in locus coeruleus neurones after injection of antisense oligonucleotides against G alpha i2, but not by injection of sense oligonucleotides against G alpha i2. Injection of antisense (or sense) oligonucleotides against G alpha i1, G alpha i3 and G alpha O (common) had no effect. These results suggest that G alpha i2 is involved in this SRIF response. 5. In AtT-20 cells, the SRIF-induced activation of inward rectifier K+ currents was suppressed by injection of anti-G alpha i3 antibody, but not by injection of anti-G alpha i1/G alpha i2 antibody. 6. The above results indicate that Gi mediates the SRIF effects on inward rectifier K+ currents. However, different subtypes of Gi are involved in the brain neurones and in the endocrine cells: Gi2 in locus coeruleus neurones and Gi3 in AtT-20 cells.

Neurotensin and dopamine D2 activation oppositely regulate the same K+ conductance in rat midbrain dopaminergic neurons

Midbrain dopaminergic neurons are excited by neurotensin (NT) and inhibited by dopamine. Interactions between these neurotransmitters have been reported, but no interaction has yet been identified at the level of ionic and signal transduction mechanisms. Using the whole-cell clamp technique, we examined the interaction of NT and quinpirole (QUIN) (a dopamine D2 agonist) on midbrain ventral tegmental area neurons cultured from the rat. We found that NT could inhibit the K+ conductance induced by QUIN. By interrupting normal signal transduction with the non-hydrolyzable GTP analogue GTPgammaS, we found that this interaction occurred downstream of the membrane neurotransmitter receptors. Similar interactions were observed between QUIN and tachykinin or metabotropic glutamate agonists.

The inhibition of motility of demembranated spermatozoa by anti-tubulin antibodies

The effects of monoclonal anti-tubulin antibodies on the motility of demembranated and reactivated sea urchin spermatozoa were investigated. Two out of ten antibodies examined significantly reduced the motility of spermatozoa, both in motile rate and swimming speed. The binding patterns of the two antibodies YL1/2 and TUB2.1 to the axoneme were studied by immunoblot, immunofluorescence, and immuno-electron microscopy. YL1/2 bound to the axoneme in a specific pattern; signals were very intense in the tail, rich in the proximal portion, and scarce in the middle part of the axoneme. Because the inhibitory effects of the antibody on the motility of spermatozoa with fully long flagella and short flagella were similar, the inhibition was probably due to the binding of the antibody to the proximal portion of the flagellum. TUB2.1 evenly bound to the axoneme by immunofluorescence and immunoelectron microscopy. On the other hand, the eight antibodies which did not affect sperm motility, did not bind to unfixed axonemes, although epitopes for these antibodies were detected abundantly in the axoneme.

Study of salivary catecholamines using fully automated column-switching high-performance liquid chromatography

Cortisol and catecholamines are major physiological markers of human stress. In order to establish a fully automated assay system for both cortisol and catecholamines in saliva, which can be sampled without imposing stress, the previously developed system for salivary cortisol [Okumura et al., J. Chromatogr. B, 670 (1995) 11] was modified. The practical sensitivity was around 0.1 pmol ml(-1) for norepinephrine and epinephrine and 0.5 pmol ml(-1) for dopamine. The established assay procedure provided R.S.D. values of 2 approximately 3% and recoveries of 96 approximately 104% at 0.5 pmol ml(-1). Measurement of salivary catecholamines in more than 300 samples taken from about 50 healthy volunteers indicated that the normal values of norepinephrine and dopamine were very low, about 0.1 pmol ml(-1) each. In contrast to cortisol, salivary catecholamine levels did not parallel those in plasma. Nevertheless, since levels of salivary catecholamines may reflect the sympathetic nerve activity in the salivary gland, they were assayed in volunteers making a scientific presentation before a large audience. Four out of eleven volunteers reported strong feelings of fear or anxiety, and their salivary catecholamine levels were about ten times higher than normal.

Effect of IL-12 on granuloma formation induced by injected Schistosoma japonicum eggs

The regulatory functions of IL-12 on granuloma formation by the eggs of S. japonicum in the lungs of BALB/c mice were studied. Mice were injected i.v. with the eggs to induce the pulmonary granuloma. On days 0, 1, 2, 3, 7, 8 after injection, mice were injected i.p. with murine rIL-12 at a dose of 1 microgram day-1 (Group I) or 3 micrograms day-1 (Group II) or with PBS as a control (Group III). On day 10, all mice were sacrificed. The areas of pulmonary granulomas in histological sections were quantitatively measured by image analyser and the levels of mRNA for IL-10, IFN-gamma, IL-12 and IL-5 were assayed by reverse transcriptase PCR (RT-PCR). The results showed that the mean area per granuloma was significantly decreased in Groups I and II as compared with Group III. As for cytokine induction, IL-10- and IFN-gamma-specific bands appeared in Groups I and II, but not in Group III. Bands for IL-5 appeared in all groups, while bands for IL-12 were not detected in any group. It is suggested that IL-12 could inhibit the Th2 dominant granuloma formation induced by the eggs of S. japonicum.

Expression of smooth muscle alpha-actin in mesenchymal cells during formation of avian endocardial cushion tissue: a role for transforming growth factor beta3

During early cardiac morphogenesis, outflow tract (OT) and atrio-ventricular (AV) endothelial cells differentiate into mesenchymal cells, which have characteristics of smooth muscle-like myofibroblasts, and which form endocardial cushion tissue, the primordia of valves, and septa in the adult heart. During this embryonic event, transforming growth factor beta3 (TGF beta3) is an essential element in the progression of endothelial-transformation into mesenchyme. TGF beta(s) are known to be a potent inducer for mesodermal differentiation and a promoter for differentiation of endothelial cells into smooth muscle-like cells. Using a monoclonal antibody against smooth muscle-specific alpha-actin (SMA), we examined the immunohistochemical staining of this form of actin in avian endocardial cushion tissue formation. To determine whether TGF beta3 initiates the expression of SMA, the pre-migratory AV endothelial monolayer was cultured with or without chicken recombinant TGF beta3 and the expression of SMA was examined immunochemically. Migrating mesenchymal cells expressed SMA beneath the cell surface membrane. These cells showed a reduction of endothelial specific marker antigen, QH1. Stationary endothelial cells did not express SMA. The deposition of SMA in the mesenchymal tissue persisted until the end of the fetal period. Pre-migratory endothelial cells cultured in complete medium (CM199) that contained TGF beta3 expressed SMA, whereas cells cultured in CM199 alone did not. At the onset of the endothelial-mesenchymal transformation, migrating mesenchymal cells express SMA and the expression of this form of actin is upregulated by TGF beta3. The induction of the expression of SMA by TGF beta3 is one of the initial events in the cytoskeletal reorganization in endothelial cells which separate from one another during the initial phenotypic change associated with the endothelial-mesenchymal transformation.

Direct evidence of a connection between autotransplanted microvessel fragments and the host microvascular system

There are no reports on the autologous transplantation and patency of microvessels in living tissue. We autotransplanted microvessel fragments (Mvf) labeled with DiI-Ac-LDL into the peritoneum and then observed the peritoneum for 7 days postoperatively with a conventional fluorescence or laser scanning confocal microscope. We illustrated a neomicrovascular network of transplanted Mvf labeled with DiI-Ac-LDL in the peritoneum with both a fluorescence and a laser scanning confocal microscope. Furthermore, we demonstrated not only the existence of erythrocytes in the lumina of transplanted DiI-Ac-LDL-labeled Mvf, but also the presence of India ink perfused through the superior mesenteric artery in the lumina of the labeled Mvf. This evidence directly suggests that transplanted Mvf can survive and proliferate to connect adjacent microvascular branches of the superior mesenteric artery in the very early phase of wound healing. Moreover, these findings imply that implantation of Mvf in the microvascular ischemic circulatory tissue might accelerate angiogenesis to reconstitute a new microvascular network connecting to the nearby host microvascular system, which ultimately improves microcirculation.

[Prediction of outcome after acute exacerbation of idiopathic interstitial pneumonia]

Some patients with chronic idiopathic interstitial pneumonia (IIP) experience acute exacerbations (AE). Because the precise mechanisms of AE in patients with IIP remain unclear, the treatment for AE is not established and the efficacy of steroids is controversial. Consequently, it is difficult to predict outcomes in patients with AE of IIP. We therefore studied the relationship between clinical findings, efficacy of treatment, and clinical outcome in patients with AE of IIP. Thirty-two patients were enrolled, and were divided into two groups: 10 who were alive more than one year after the onset of the AE survivors, 8 men and 2 women, and 22 who died within one year of the AE (non-survivors, 17 men and 5 women). Survivors were significantly younger than non-survivors (59.7 +/- 9.9 vs 67.5 +/- 8.2 years, respectively, p < 0.05). The values of PaCO2 measured before the AE were higher in survivors than in non-survivors (43.0 +/- 3.7 vs 38.4 +/- 4.0 torr, respectively, p < 0.05). At the onset of the AE the levels of C-reactive protein in serum were higher in survivors than in non-survivors (13.9 +/- 7.9 vs 7.3 +/- 5.8 mg/dl, respectively, p < 0.05). Chest X-ray films showed progression of ground-glass shadows in both groups when the AE occurred; the radiographic findings did not differ markedly between groups. Of the 22 non-survivors, 7 had received medication before the AE; none of the survivors had received medication before the AE. At the time of the AE all patients were treated with steroid pulse therapy, and the dose of methylprednisolone used, did not differ significantly between groups. These data suggest that three factors are closely related to responsiveness to steroid therapy and to clinical outcomes after AE in patients with IIP: 1) age at the onset on IIP, 2) respiratory status before the AE, and 3) disease activity as reflected by inflammatory reactions.

Visual evoked potentials relating to imagery: words for concrete objects versus absolute concepts

We recorded visual evoked potentials (VEPs) elicited with high or low imaginable Chinese characters (HIC or LIC), representing concrete objects or absolute concepts, respectively. A closed circle (CC) acts as control stimulus. These were displayed (at 1.6 degrees visual angle) for 35 ms on a TV monitor. Twenty-one channel VEPs (band-pas filter: 0.05-60 Hz), using balanced non-cephalic electrodes, were recorded from -100 to 924 ms for 11 right-handed male volunteers. The VEPs were analyzed by multivariate analysis of variance (MANOVA) and comparison of topographies at four remarkable peaks (P110, N160, P230 and N320). MANOVA showed significant differences (p < 0.001) for both conditions of channel and stimuli (HIC, LIC or CC). P100 for the CC-VEPs, N160 for the HIC- and LIC-VEPs, P230 for the CC-VEPs, and N320 for the HIC-VEPs were remarkable in the posterior scalp regions. Topographies at P100 and N160 showed no difference between the HIC- and LIC-stimuli. However, those at N320 showed difference between the HIC- and LIC-stimuli over the occipital and posterior temporal areas. Those results suggest that the responses at P100 and N160 might segregate Chinese characters from non Chinese characters. N320 suggested certain processes in imagery on recognizing Chinese characters over the occipital and posterior temporal areas.

[A case of myeloperoxidase-antineutrophil cytoplasmic antibody (ANCA)-positive crescentic glomerulonephritis induced by propylthiouracil (PTU)]

We have experienced a case of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-related glomerulonephritis induced by propylthiouracil (PTU). A 45-year-old female had been treated with PTU for 4 years after the diagnosis of hyperthyroidism. She was referred to out hospital because of abrupt macroscopic hematuria and moderate proteinuria after several days of upper respiratory tract infection. On admission, her laboratory findings showed deterioration of renal function. Renal biopsy revealed crescentic glomerulonephritis without deposition of immune complexes. Her serology was found to be MPO-ANCA-positive and cytoplasmic-ANCA-negative. Based of these findings, we diagnosed idiopathic crescentic glomerulonephritis. Following the initiation of steroid pulse therapy, her urinary protein excretion and renal function gradually improved in parallel with a decrease in the MPO-ANCA titer. Although steroid therapy effectively responded to their renal function without the withdrawal of PTU, it seems that PTU may be closely associated with the development of (MPO-ANCA)-related glomerulonephritis in this case. Therefore, hyperthyroidism patients treated with PTU should be paced under vigilant observation by monitoring their urinalysis and serum creatinine level.

Association of reduced cell adhesion regulator messenger RNA expression with tumor progression in human hepatocellular carcinoma

The recently identified cell adhesion regulator (CAR) modulates the process of integrin-mediated cell adhesion. The CAR gene is located on 16q, a locus at which high levels of allelic losses have been demonstrated in advanced human hepatocellular carcinoma (HCC). We studied the possible involvement of the CAR gene in the progression of HCC. With this aim, we determined the expression of CAR mRNA in 30 cases of HCC. Matching pair samples of tumor and adjacent nontumoral liver were analyzed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The results were compared with the clinicopathological features of the patients. Every nontumoral liver tissue sample analyzed, expressed CAR mRNA. All tumor samples showed amounts of expression that were equal or lower, compared with those found in their matching controls. Thus, in 16 out of 30 cases (53.3%), CAR mRNA expression in tumor was diminished to less than one tenth of that observed in nontumoral tissue. This group of patients exhibited higher amounts of alpha-fetoprotein, and comprised tumors with poor histological differentiation (Edmondson-Steinert's grades III-IV), higher rates of intrahepatic metastasis and recurrence within the first postoperative year (p < 0.05, respectively). Tumors exhibiting low levels of CAR mRNA were also found to be diagnosed at more advanced TNM stages (p < 0.01). We conclude that downregulation of CAR mRNA expression may play an essential role in the progression of HCC.

Dopamine and GABA receptors in cultured substantia nigra neurons: correlation of electrophysiology and immunocytochemistry

Primary neuron cultures were made separately from the substantia nigra pars compacta and the substantia nigra pars reticulata of neonatal rats. Using the whole-cell patch-clamp, we tested for the presence of dopamine and GABA receptor subtypes by applying dopamine receptor agonists [the D2 receptor agonist quinpirole and the D1 receptor agonist R(+)-SKF-38393] and GABA receptor agonists (GABA and baclofen). The D2 agonists and the GABA(B) agonist increased an inward rectifier K+ conductance, while the D1 agonist decreased this K+ conductance. Application of GABA increased membrane conductance, probably by increasing Cl- permeability through GABA(A) receptors. Following the physiological tests, the same neuron was examined by double immunocytochemical labeling for antibody to tyrosine hydroxylase and antibody to GABA. Neurons which responded to the D2 agonist were dopaminergic neurons, while neurons which did not respond to D2 agonist were mostly GABAergic or non-dopaminergic/non-GABAergic. Neurons which responded to the D1 agonist were non-dopaminergic/non-GABAergic. GABA(A) receptors were present in all types of neurons, while GABA(B) receptors were located on some dopaminergic neurons and some GABAergic neurons. These results largely agree with the published data on in vivo or brain slice preparations, indicating that these neurons of neonatal rat brains, after being dissociated, produce the same transmitters and the same receptors in culture as those in vivo.

Association of interleukin-6 in the cerebrospinal fluid during crisis of calf with ammoniated feed syndrome

Ammoniated feed syndrome (AFS) in cattle is a neurotoxic syndrome caused by feeding specific ammoniated forage. To clarify the pathophysiology of AFS, we examined the association of interleukin-6 (IL-6) in the brain. By feeding milk either from cows fed such ammoniated forage or milk added with 4-methyl-imidazole, newborn calves showed a neurotoxic crisis of hyperexcitability, ataxia, muscle tremor, circling, roaring, epileptoid seizure, sweating and marked fever response. Although these calves had no pathological lesions in the brain, we detected a rise in IL-6 in the cerebrospinal fluid (CSF). Tumor necrosis factor-alpha (TNF-alpha) was not detected in the CSF. In the sera, IL-6 and TNF-alpha hardly changed during the experiment. Administration of recombinant human IL-6 into the lateral ventricle resulted in fever. Thus, we believe IL-6 in the CSF is related to the fever response in newborn calves with AFS.

Serum-free culture of adult chicken hepatocytes; morphological and biochemical characterisation

The morphological and biochemical characterisation of adult chicken hepatocytes in a serum-free culture are described. When cultured in positively charged plastic dishes, chicken hepatocytes formed a monolayer cell sheet. The monolayer morphology of these chicken hepatocytes was quite distinct from the spheroid shape of rat hepatocytes cultured under similar conditions. Electron microscopy showed that the cytoplasmic organelles of chicken hepatocytes were well preserved in vitro. Two-dimensional gel electrophoresis showed that the chicken hepatocytes secreted liver-specific proteins. Several enzymes of glucose-6-phosphatase, cytochrome P-450 or glutathione S-transferase, involved in metabolic and biotransformation pathways in the liver, were retained in the chicken hepatocytes in a serum free condition. These findings suggest that the primary culture of adult chicken hepatocytes with a serum-free culture system could be useful to study the hepatic metabolic pathway in the chicken and its response to various chemicals.

Analysis of extracellular matrix proteins in malignant chicken cell lines

The adherent chicken cell line, MDCC-MSB1-41C, was highly transplantable and metastatic in vivo, compared with the parental non-adherent cell line MDCC-MSB1 from Marek's disease (MD) lymphoblastoid tumor. For clarification of differences in extracellular matrix proteins in MSB1-41C and MSB1 cells, examination was made of various components of extracellular matrix proteins. A detachment experiment indicated the protein(s) recognizing the Arg-Gly-Asp (RGD) sequence, the minimum structure required for recognition by the cell-surface receptors, is essential for the adherent character. Immunoblot assay using antibodies showed increased expression of fibronectin, fibronectin receptors, and vinculin on MSB1-41C cell lines. RGD-directed integrins mediate important cell-cell adhesive interaction and these interactions with extracellular matrix proteins may thus possibly be requisite for migration, proliferation and metastatic dissemination of MDCC-MSB1-41C cells. The RGD-containing peptide in the culture medium could cause detachment of cultured adhesive lymphoid leukosis LSCC-1104X5 cells from the dish too.

[Resistance to macrolides]

Resistance mechanisms to macrolide antibiotics involving lincosamide and streptogramin type B antibiotics were described in bacteria. Phenotype in the resistant microorganism is generally observed as one of two characteristics, i.e., decrease of intracellular macrolide-accumulation and inactivation of the drugs. The former phenotypic resistance results from one of three mechanisms: (1) mono- or di- methylation of a specific adenine residue in 23 S ribosomal RNA and (2) impaired uptake and (3) enhanced efflux of the antibiotics. The latter is caused by one of two mechanisms: (1) degradation of the drugs by a hydrolytic enzyme such as an esterase and (2) drug modification by one of enzymes such as nucleotidyl- and phospho- transferases.

Budd-Chiari syndrome resulting from intrahepatic IVC compression secondary to blunt hepatic trauma

Hepatic venous outflow obstruction (Budd-Chiari syndrome)is a rare sequel of abdominal trauma. Three cases of Budd-Chiari syndrome resulting from obstruction to the intrahepatic IVC by liver injury are reported. The CT findings include extrinsic compression of the intrahepatic inferior vena cava (IVC) by intraparenchymal and/or subcapsular hepatic haematoma, non-visualization or narrowing of one or more main hepatic veins with intravenous contrast-enhanced CT, and accumulation of low attenuation ascites. This entity should be distinguished from intraperitoneal bile leak or hemoperitoneum associated with major liver injury with which it could be confused. Decompression of the IVC and hepatic veins by surgical or percutaneous drainage of intrahepatic or subcapsular hematoma was curative in two of the three patients.

Elevated levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) activities in the sera and milk of cows with naturally occurring coliform mastitis

The presence of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) activities was determined in milk and serum of cows with naturally occurring coliform mastitis (CFM). TNF-alpha was detected in the sera from 26 of 32 cows with CFM. TNF-alpha levels were higher in the sera than in the milk. IL-6 was high in the sera of surviving CFM animals, but was low in animals that died and in healthy controls. Furthermore, the mean level of IL-6 was 20-fold higher in the milk than in the sera of mastitic cows. The level of IL-6 in the serum was correlated to that in the milk in individual animals. The presence of IL-6 and TNF-alpha in the sera appears to relate to severe clinical condition of CFM, in the milk whereas they may play a role in generating inflammation of the mammary gland.

A guide to preventing deep insertion of the cannulation needle during catheterization of the internal jugular vein

OBJECTIVE

Accidental puncture of the vertebral artery during the internal jugular vein cannulation produces lethal sequelae. To prevent this, the cannulation needle must not be inserted too deeply. However, there is no useful guide for the optimal length of insertion of the needle for accessing the internal jugular vein. The authors examined the length of the needle needed to reach the internal jugular vein with three different sizes of needle (16, 20, and 23 gauge).

DESIGN

Prospective study.

SETTING

An academic medical center.

PARTICIPANTS

Patients undergoing cardiovascular surgeries.

INTERVENTIONS

The cannulation of the internal jugular vein was performed through the right internal jugular vein by the high approach. The needle was slowly advanced, keeping constant negative pressure on the syringe at 45 degrees to the skin surface until blood was aspirated; if blood was not aspirated during insertion, the needle was slowly withdrawn until blood was aspirated. The distance to the internal jugular vein was assessed by calculating the entire length of needle minus the length of needle from the skin surface to the hub.

MEASUREMENTS AND MAIN RESULTS

The mean distance to the internal jugular vein ranged from 15.0 to 21.5 mm, and the larger needle required the longer distance to the internal jugular vein.

CONCLUSIONS

The results may be a useful guide to prevent too deep insertion of the needle during internal jugular vein catheterization, especially when teaching residents who have limited experience with internal jugular vein catheterization.

[Length of survival of elderly patients with chronic obstructive pulmonary disease]

We examined survival in 53 patients over 60 years old who had chronic obstructive pulmonary disease, and whose FEV1 was less than 60% of the forced vital capacity and was less than 60% of the predicted value. They comprised 34 men and 19 women. The mean age was 75.2 years. The %FEV1 was 39.0% and the body mass index was 19.0. Neither age %FEV1, nor body mass index differed significantly between men and women. However, the number of cigarettes smoked per day, the number of years of cigarette smoking, and the Brinkman index were higher in men than in women. The Brinkman index was 1255.0 in men and 617.8 in women (p = 0.0001). For the group as a whole, the 5-year survival rate was 65% and the 10-year survival rate was 35%. The survival rate of men did not differ from that of women. Survival and %FEV1 did not differ between men and women, despite the significant difference in Brinkman index, which suggests that women were more susceptible to the effects of cigarette smoking than men. Age, one tenth of %FEV1, and body mass index less than 19 were found to be independent predictors of mortality (proportional hazards analysis, p = 0.044, 0.019, and 0.024, respectively). The 5-year survival rate were as follows: 85% in patients less than 75 years of age, 50% in patients more than 75 years of age, 25% in patients with a %EFV1 less than 30%, 80% in patients with a %FEV1 of 30% to 49%, 62% in patients with a %FEV1 of 50% to 60%, 50% in patients with a body mass index of less than 19, and 83% in patients with a body mass index of more than 19.

Phosphatidylinositol 3-kinase is not required for recycling of mannose 6-phosphate receptors from late endosomes to the trans-Golgi network

Mannose 6-phosphate receptors carry newly synthesized lysosomal hydrolases from the trans-Golgi network to endosomes, then return to the trans-Golgi network for another round of enzyme delivery. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase, interferes with the delivery of newly synthesized lysosomal enzymes to lysosomes. We used two independent assays of mannose 6-phosphate receptor trafficking to determine the precise step that is blocked by wortmannin. Using an assay that monitors resialylation of desialylated cell surface 300-kDa mannose 6-phosphate receptors, we found that receptor endocytosis and transport to the trans-Golgi network were not inhibited by 2 microM wortmannin. In addition, this concentration of drug had no effect on the transport of the mannose 6-phosphate receptor from late endosomes to the trans-Golgi network using a system that reconstitutes this transport process in cell extracts. Under the same conditions, wortmannin significantly inhibited the generation of mature cathepsin D. In addition, the structurally unrelated phosphatidylinositol 3-kinase inhibitor, LY294002, was also without effect when added to in vitro endosome-trans-Golgi network transport reactions. These experiments demonstrate that the interruption in lysosomal enzyme targeting is most likely due to a wortmannin-sensitive process required for the export of these receptors from the trans-Golgi network, consistent with the established role of phosphatidylinositol 3-kinase in the equivalent transport process in Saccharomyces cerevisiae.