Characterization of rat receptor-like protein tyrosine phosphatase gamma isoforms

We identified four isoforms of receptor-like protein tyrosine phosphatase gamma (RPTPgamma) from rat brain by cDNA cloning. We designated these molecules RPTPgamma-A, -B, -C, and -S. RPTPgamma-A was the longest form and had the same structure as human and mouse RPTPgamma. RPTPgamma-B lacked the intracellular juxtamembrane 29 amino acids of RPTPgamma-A. RPTPgamma-C had a single phosphatase domain. RPTPgamma-S is an extracellular variant of RPTPgamma. mRNAs of the four isoforms were expressed in the brain, kidney, lung, and heart. Transfection of RPTPgamma-A and -S expression plasmids into COS7 cells resulted in the expression of membrane-bound 190-kDa proteins and secreted 120-kDa proteins, respectively. These molecules were similar to PTPzeta/RPTPbeta with regard not only to structure but also to the presence of both secretory and transmembrane forms. However, RPTPgamma isoforms were not expressed as proteoglycans.

[Primary localized amyloidosis of the urinary bladder: a case report]

A case of primary localized amyloidosis of the urinary bladder is reported. A 57-year-old male who complained of macrohematuria visited our hospital. Cystoscopic examination revealed a broad basic tumor from the anterior wall to the right wall. Suspecting a bladder tumor we performed a transurethral resection. However, the histopathological examination of the specimen revealed amyloid deposition and no malignant changes. Serum electrophoresis pattern was normal and urinary Bence-Jones protein was negative. Neither rectal nor gastric biopsy revealed amyloids. From these findings, we made a diagnosis of the primary localized amyloidosis of the urinary bladder. We collected 42 cases from the Japanese literature and discuss the clinical features of this disease.

Effects of chronic isoproterenol treatment or submandibular and sublingual ablation on microflora of mouse tooth surfaces

BALB/cA mice were examined for the effects of chronic isoproterenol treatment or submandibular-sublingual gland ablation on the natural patterns of oral bacterial colonization on tooth surfaces. Indigenous microflora on the tooth surfaces of BALB/cA mice was relatively simple. The predominant bacterial groups were Enterobacteriaceae (45.9%), enterococci (29.4%) and staphylococci (15.7%). Isoproterenol, which resulted in the induced synthesis of proline-rich proteins, caused a decrease in the total cultivable bacteria on the tooth surfaces. The proportion of Enterobacteriaceae in the isoproterenol-treated mice decreased, although the proportion of other bacterial groups increased. Salivary gland ablation, which caused the loss of mucins in saliva, showed essentially the same number of total bacteria as the control. Salivary gland ablation resulted in a decrease in the proportion of Enterobacteriaceae, while the proportion of Gram-positive rods and staphylococci increased.

Detection of alterations in the levels of neuropeptides and salivary gland responses in the non-obese diabetic mouse model for autoimmune sialoadenitis

The salivary glands of non-obese diabetic (NOD) mice and BALB/c controls were evaluated for the stimulatory effects of the following neuropeptides; substance P (SP), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY). Injection of either of the three neuropeptides in combination with the muscarinic-cholinergic agonist pilocarpine increased saliva flow rates in BALB/c mice while there was no observable augmentation to flow rates in pre-diabetic or diabetic NOD mice. Small increases in protein content of the stimulated saliva were observed in the BALB/c group of animals with the injection of any of the above neuropeptides in combination with pilocarpine. In pre-diabetic NOD animals, only VIP and NPY increased the protein content-ratio above pilocarpine alone. Radioimmunoassay determination of neuropeptide concentrations in the submandibular and parotid glands revealed reduced levels of SP with diabetes onset as compared with pre-diabetic NOD or BALB/c mice. The levels of NPY were similar between BALB/c and NOD animals except in the pre-diabetic parotid gland where NPY concentrations were 1.3-fold greater. On the other hand, VIP concentrations were substantially reduced in the submandibular gland of NOD mice, while in the parotid gland neuropeptide levels were evaluated 3.8-fold relative to BALB/c controls. Immunohistochemical staining of the parotid and submandibular glands for SP revealed primarily ductal cell staining which was reduced with diabetes onset in NOD animals. These findings further define the sialoadenitis observed in NOD mice to be due, in part, to a general loss of neurotransmitter responsiveness on the part of salivary gland cells.

[Health status, social networks and support systems of so called old old in a population-based comparative study of residents ages 69-74 and 75-80]

To analyze the different features of health status, social support and networks of elderly people by age groups, a survey was performed of the social environment and health related issues among residents aged 69-74 and 75-80, the so called old-old, in Takasu, a small farming town in Hokkaido. The results were as follows: 1. The percentage of elderly having some of the symptoms related to dementia, lower scores of ADL, and poorer conditions of eye sight or hearing were significantly higher among the elderly aged 75-80 compared to those aged 69-74. The prevalence of diseases, such as senile cataracts in both sexes, and heart diseases in men were also higher among those aged 75 and over. 2. Although there were no differences in the mean number of hospital admissions or in the percentage of those having been sick in bed for more than 1 week during the previous one year, both the mean number of out-patient visits and percentage having a family physician were significantly higher in the elderly over 75 than under. Deterioration of IADL were prominent in the item on being able to go far away by themselves. 3. Almost 70% of the elderly participated in community-based social activities in Takasu. There were only small differences in social support and network among the different categories of family structure of the elderly. However women over 75 had statistically significantly lower number of the social supports compared to the younger age groups. A significantly smaller percentage of people was able to obtain the emotional or care support from their spouse for in elderly over 75 than for elderly under 75. 4. The results of this study suggest the need to provide more social support and networks for the old-old over 75 years old who tend to have more diseases and to be in poorer health condition, both physically or mentally than younger old.

Cortical hypometabolism and delayed myelination in West syndrome

PURPOSE

We examined the relation between cortical hypometabolism and delayed myelination in patients with West syndrome (WS).

METHODS

Serial positron emission tomography (PET) with [18F]fluorodeoxyglucose ([18F]FDG) and magnetic resonance imaging (MRI) were performed in 18 patients with WS, first at the onset of epileptic spasms and later at age 10 months. The age at onset of seizures ranged from 2 to 7 months. Ten patients were diagnosed as having cryptogenic WS and 8 as having symptomatic WS.

RESULTS

Cortical hypometabolism was detected in many patients at onset of epilepsy, but disappeared later, whereas delayed myelination tended to become evident with age. PET showed diffuse or focal cortical hypometabolism in 12 patients at onset, but in only 6 patients at age 10 months. MRI showed delayed myelination in only 2 patients at onset of epilepsy, but the number of patients with delayed myelination increased to 12 at age 10 months. Delayed myelination was more often present in patients with cortical hypometabolism. Delayed myelination was noted in 11 (85%) of 13 patients with cortical hypometabolism on first or second PET scans, but in only 1 (20%) of 5 patients who did not show PET abnormalities. Hypometabolism on the first or second PET scan was positively correlated with delayed myelination at age 10 months.

CONCLUSIONS

In patients with WS, assessing myelination with MRI again at age 8-10 months is important even when MRI at the onset of epilepsy appears normal. Serial MRI and PET scans disclose more detailed pathophysiology of WS.

FK960 N-(4-acetyl-1-piperazinyl)-p-fluorobenzamide monohydrate ameliorates the memory deficits in rats through a novel mechanism of action

With passive avoidance (PA), Morris water maze (WM) and eight-arm radial maze tasks, we evaluated the memory-enhancing action of FK960 [N-(4-acetyl-1-piperazinyl)-p-fluorobenzamide monohydrate], a compound which we have found through rational drug screening based on our hypothesis that penile erection is a valid predictor of central cholinergic activation. Memory performance in the tasks was impaired in aged (24- to 26-months-old) rats as well as in rats with nucleus basalis magnocellularis lesions. Scopolamine (1 mg/kg i.p.) treatment induced memory impairment in PA and WM; treatment with cysteamine (200 mg/kg s.c.) induced memory impairment in PA but not in WM, whereas fimbria fornix lesioning affected the rats in the opposite manner. FK960 (0.1-10 mg/kg i.p.) ameliorated all the memory impairments except those induced by cysteamine or fimbria fornix lesion, and the dose-response curves were bell shaped with maximal response at 1 to 3.2 mg/kg. The effects of FK960 on the scopolamine-induced memory impairment in the PA and/or WM were abolished by cysteamine (200 mg/kg s.c.), dl-p-chlorophenylalanine methyl ester hydrochloride (150 mg/kg i.p. for 3 days) or raphe lesioning, but not by neonatal 6-hydroxydopamine (35 micrograms/head) treatment. Neurochemical analysis revealed that cysteamine and raphe lesions reduced brain somatostatin and serotonin contents, respectively. The treatment with FK960 (0.32-320 mg/kg p.o.) dose-dependently increased both serotonin and 5-hydroxyindoleacetic acid levels in the brain areas examined and significantly increased hippocampal somatostatin contents at the smaller doses. From these results, we conclude that FK960 ameliorates cognitive dysfunction through an activation of the somatostatinergic-serotonergic link.

Cryptogenic localization-related epilepsy of neonatal onset

We report three patients with localization-related epilepsy of neonatal onset. They exhibited favourable psychomotor development and had no cerebral lesions on neuroimaging studies despite the presence of intractable partial seizures of neonatal onset. Although rare, some cases of epilepsy of neonatal onset may be cryptogenic, i.e. they belong to neither the symptomatic nor the idiopathic group.

Erythrocyte flow and elasticity of microvessels evaluated by marginal cell-free layer and flow resistance

Flow dynamics of human erythrocytes was compared in elastic (E) and hardened (H) microvessels with inner diameters of 10-40 microns. The thickness of the marginal cell-free layer and the overall flow resistance were measured with a vascular bed isolated from rabbit mesentery (E vascular bed) as well as with a 4% paraformaldehyde-fixed bed (H vascular bed). 1) In both E and H microvessels, the thickness of the cell-free layer increased with increasing inner diameter of the microvessels and with decreasing hematocrit accompanied by an overall decrease in the flow resistance. The hematocrit-dependent change of the cell-free layer thickness was greater in the E microvessels than in the H microvessels. The flow resistance was always greater in the H vascular beds than in the E vascular beds. 2) With decreasing erythrocyte deformability induced by treatment with 2 mM diazenedicar-boxylic acid bis(N,N-dimethylamide), the thickness of the cell-free layer decreased at a low hematocrit in the E microvessels and at a high hematocrit in the H microvessels, although the flow resistance was increased in both vascular beds. 3) Dextran of 70,400 average molecular weight accelerated the formation of the cell-free layer by inducing erythrocyte aggregation. A drastic increase in the cell-free layer thickness at 2-4 g/dl of dextran in the E microvessels and at 1-2 g/dl of dextran in the H microvessels was accompanied by a significantly lower increase in the flow resistance. This study concludes that the elasticity of microvessels may play an important role for reducing the overall flow resistance of a vascular bed, which is modulated by the marginal cell-free layer, itself a function of the rheological properties of the erythrocytes.

Effects of GM-CSF and ordinary supplements on the ramification of microglia in culture: a morphometrical study

Microglia transform from ameboid to ramified cells during development and display an ameboid appearance again under certain pathological conditions. Some cytokines produced by astrocytes may be responsible for the microglial transformation. In the present study, we compared the effects of cytokines, granulocyte/macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), and interleukin-3 (IL-3) on the morphology of rat cultured microglia. For quantitative evaluation, we employed "transformation index" as calculated by (perimeter of cell)2/4 pi (cell area). GM-CSF facilitated the ramification of cultured rat microglia, which was effectively induced in a serum-free medium. However, M-CSF and IL-3 did not induce the ramification. A certain serum adhesion protein (possibly vitronectin) as well as other high molecular weight substances in fetal calf serum inhibited the GM-CSF-induced microglial ramification. Among ordinary supplements for a chemically defined medium, progesterone, insulin, and a high concentration of glucose suppressed the ramification. These findings suggest that GM-CSF may be involved in microglial ramification and that many kinds of supplements that are added to culture media profoundly affect the morphology of microglial cells.

Elevated blood pressures in mice lacking endothelial nitric oxide synthase

Nitric oxide produced in endothelial cells affects vascular tone. To investigate the role of endothelial nitric oxide synthase (eNOS) in blood pressure regulation, we have generated mice heterozygous (+/-) or homozygous (-/-) for disruption of the eNOS gene. Immunohistochemical staining with anti-eNOS antibodies showed reduced amounts of eNOS protein in +/- mice and absence of eNOS protein in -/- mutant mice. Male or female mice of all three eNOS genotypes were indistinguishable in general appearance and histology, except that -/- mice had lower body weights than +/+ or +/- mice. Blood pressures tended to be increased (by approximately 4 mmHg) in +/- mice compared with +/+, while -/- mice had a significant increase in pressure compared with +/+ mice (approximately 18 mmHg) or +/- mice (approximately 14 mmHg). Plasma renin concentration in the -/- mice was nearly twice that of +/+ mice, although kidney renin mRNA was modestly decreased in the -/- mice. Heart rates in the -/- mice were significantly lower than in +/- or +/+ mice. Appropriate genetic controls show that these phenotypes in F2 mice are due to the eNOS mutation and are not due to sequences that might differ between the two parental strains (129 and C57BL/6J) and are linked either to the eNOS locus or to an unlinked chromosomal region containing the renin locus. Thus eNOS is essential for maintenance of normal blood pressures and heart rates. Comparisons between the current eNOS mutant mice and previously generated inducible nitric oxide synthase mutants showed that homozygous mutants for the latter differ in having unaltered blood pressures and heart rates; both are susceptible to lipopolysaccharide-induced death.

Colocalization of immunoglobulin binding factor and prostate specific antigen in human prostate gland

Immunoglobulin binding factor (IgBF) produced in the prostate is a useful marker for the diagnosis of prostatic tumor. IgBF was localized in the majority of epithelial cells of benign prostatic hypertrophy by an immunohistochemical technique. Prostate specific antigen (PSA), a known marker for prostatic cancer, was localized to all epithelial cells. Double immunolabeling of IgBF and PSA using fluorescent methods revealed that all epithelial cells producing IgBF were also immunopositive for PSA and some cells were positive only for PSA. The present findings suggest that the prostatic glands consist of two types of epithelial cells, one producing both IgBF and PSA and the other producing PSA alone.

Presence of immunoglobulin binding factor on human sperm surface as sperm coating antigen

The presence of IgBF as a sperm-coating antigen was demonstrated by showing that anti-IgBF antibodies agglutinate and immobilize human sperm and by localizing IgBF on sperm surface by immunofluorescence staining. Several components interacting with sperm immobilizing antibodies, known to be involved in infertility, are sperm-coating antigens. Anti-IgBF antibody in vitro did not block the ability of human sperm to penetrate human zona pellucida and zona-free hamster egg. Anti-IgBF activity of sera obtained from infertile women did not correlate with the titers of anti-sperm antibodies measured by the sperm immobilization test. IgBF is a sperm-coating antigen and may play a role in suppressing antibody production against alloantigenic sperm in the female reproductive tract.

Autonomous control of expression of genes for insulin-like growth factors during the proliferation and differentiation of C2C12 mouse myoblasts in serum-free culture

The proliferation and differentiation of skeletal muscle cells in culture are usually controlled by serum components, and the differentiation can be induced by a reduction in the serum concentration. Insulin-like growth factors (IGFs) play a critical role in stimulating myoblast differentiation, and the expression of their genes is controlled by serum factors. We have found that C2C12 myoblasts are capable of proliferation and differentiation even in serum-free medium that does not contain peptide mitogens. During these processes in serum-free medium, the accumulation of mRNAs for IGFs in the cells was observed; and their levels increased with concomitant increases in creatine kinase activity and myotube formation and a decrease in DNA synthesis. Thus, the present results suggest that proliferation and differentiation of C2C12 cells are autonomously controlled and that the increase in the expression of the IGFs may be independent of exogenous components.

Identification and characterization of a mitochondrial endonuclease from yeast, Schizosaccharomyces pombe

Schizosaccharomyces pombe mitochondria were isolated from the cells treated with Novozyme 234, and purified in a Percoll gradient. A zymographic assay in a SDS-polyacrylamide gel containing single-stranded DNA revealed that an endonuclease of 32 kDa is associated with the mitochondria. The endonuclease was extracted from the mitochondria with 0.5 M KCl and was partially purified. The 32-kDa enzyme degraded both DNA and RNA at a weak alkaline pH, but preferred single-stranded DNA. The enzyme required Mg2+ or Mn2+, but not Ca2+ or Zn2+ for activity, and was inhibited by 50% with a 150 mM salt solution. Nicks generated by the enzyme could be resealed with T4 DNA ligase, indicating that the enzyme produces 5'-P and 3'-OH ends.

Two distinct apolipoprotein B alleles in mice generated by a single 'in-out' targeting

'In-out' gene targeting using a hypoxanthine phosphoribosyltransferase (HPRT) minigene was applied to generate two new alleles in the gene (Apob) coding for apolipoprotein B (apo B) in murine embryonic stem (ES) cells. Homologous integration of the targeting vector during the 'in step' disrupted the Apob gene leading to an allele encoding apo B81, having a 19% carboxyl-terminal truncation. All six targeted cells obtained had more than one insert at the locus, and the chromosomal target sequence in four of them was changed during the recombination. These results suggest that concatenation of the targeting vector prior to insertion was needed to generate sufficient gene product to yield the HPRT+ phenotype, and that recombination between the concatenated DNA and endogenous DNA was a gene replacement more frequently than a simple insertion. The 'out step' recombination event which occurs between sequences duplicated in the 'in step', was planned to replace the sequences encoding the putative LDL receptor-binding domains of apo B100 with sequences encoding human beta-globin peptides (designated apo B100-beta). 6-Thioguanine (6-TG) resistant colonies were obtained from all the 'in-step' cell lines tested at frequencies of 10(-5) to 10(-4), but the frequency of physical loss of the HPRT sequences accompanied by retention of the modified Apob sequence was variable, indicating that mechanisms other than a simple excision are responsible for the generation of 6-TG resistance. Mice from the 'in-step' produce apo B81 and display characteristics of familial hypobetalipoproteinemia; some homozygotes develop hydrocephaly or exencephaly. Mice from the 'out-step' produce apo B100-beta and secrete lipoprotein particles containing the modified protein; their phenotypic changes are subtle, suggesting the lack of the putative LDL receptor-binding domains is not sufficient to increase the steady-state level of apo B100-beta particles above that of apo B100 particles in control mice.

Analysis of protein structure-function in vivo. Adenovirus-mediated transfer of lipase lid mutants in hepatic lipase-deficient mice

Hepatic lipase (HL) and lipoprotein lipase (LPL) are key enzymes involved in the hydrolysis of triglycerides and phospholipids present in circulating plasma lipoproteins. Despite their similarities, the role that each of these two lipases play in the metabolism of triglyceride-rich lipoproteins and high density lipoproteins is distinct. In order to identify structural domains that may confer the different substrate specificities between HL and LPL, we have utilized a novel approach for performing structure-function analysis of a protein, in vivo, by using recombinant adenovirus vectors to express native and mutant enzymes in an animal model for a human genetic deficiency. HL-deficient mice (n = 19) characterized by increased plasma cholesterol and phospholipid concentrations were injected with adenovirus expressing luciferase (rLucif-AdV), native hepatic (rHL-AdV), and lipoprotein lipase (rLPL-AdV) or lipase mutants in which the lid covering the catalytic site of either enzyme was exchanged (rHL+LPL lid-AdV and rLPL+HL lid-AdV). Mice injected with rLucif-AdV had no changes in post-heparin HL and LPL activities (217 +/- 29 and 7 +/- 2 nmol/min/ml, respectively) as well as plasma lipids. Despite expression of similar levels of post-heparin plasma lipase activity on day 5 post-adenovirus infusion (9806 +/- 915 and 9677 +/- 2033 nmol/min/ml, respectively) mice injected with rHL-AdV or rHL+LPL lid-AdV demonstrated marked differences in the reduction of plasma phospholipids (70% and 32%, respectively, p < 0.005). Similarly, despite post-heparin plasma lipolytic activities of 4495 +/- 534 and 4844 +/- 1336 nmol/min/ml, injection of rLPL-AdV or rLPL+HL lid-AdV resulted in phospholipid reductions of 31% and 81% (p < 0.005). Exchange of the lipase lid did not significantly alter plasma triglyceride concentrations. Thus, preferential in vivo hydrolysis of phospholipids was demonstrated in animals expressing lipases containing the HL lid but not the LPL lid. These studies identify the lipase lid as a major structural motif responsible for conferring the different in vivo phospholipase activities between HL and LPL, a function which may modulate the distinct physiological roles of these two similar lipolytic enzymes in lipoprotein metabolism. The use of recombinant adenovirus to express mutant proteins in animal models for human genetic deficiencies represents a powerful, new approach for performing structure-function analysis of proteins in vivo.

Hepatocellular and hepatic peroxisomal alterations in mice with a disrupted peroxisomal fatty acyl-coenzyme A oxidase gene

Peroxisomal genetic disorders, such as Zellweger syndrome, are characterized by defects in one or more enzymes involved in the peroxisomal beta-oxidation of very long chain fatty acids and are associated with defective peroxisomal biogenesis. The biologic role of peroxisomal beta-oxidation system, which consists of three enzymes: fatty acyl-CoA oxidase (ACOX), enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase (HD), and thiolase, has been examined in mice by disrupting ACOX gene, which encodes the first and rate-limiting enzyme of this system. Homozygous (ACOX -/-) mice lacked the expression of ACOX protein and accumulate very long chain fatty acids in blood. However, these homozygous mice are viable, but growth-retarded and infertile. During the first 3-4 months of age, the livers of ACOX -/- mice reveal severe microvesicular fatty metamorphosis of hepatocytes. In such steatotic cells, peroxisome assembly is markedly defective; as a result, they contain few or no peroxisomes. Few hepatocytes in 1-3-month-old ACOX -/- mice contain numerous peroxisomes, and these peroxisome-rich hepatocytes show no fatty change. At this stage, the basal mRNA levels of HD, thiolase, and other peroxisome proliferator-induced target genes were elevated in ACOX -/- mouse liver, but these mice, when treated with a peroxisome proliferator, showed no increases in the number of hepatic peroxisomes and in the mRNAs levels of these target genes. Between 4 and 5 months of age, severe steatosis resulted in scattered cell death, steatohepatitis, formation of lipogranulomas, and focal hepatocellular regeneration. In 6-7-month-old animals, the newly emerging hepatocytes, which progressively replaced steatotic cells, revealed spontaneous peroxisome proliferation. These livers showed marked increases in the mRNA levels of the remaining two genes of the beta-oxidation system, suggesting that ACOX gene disruption leads to increased endogenous ligand-mediated transcription levels. These observations demonstrate links among peroxisomal beta-oxidation, development of severe microvesicular fatty liver, peroxisome assembly, cell death, and cell proliferation in liver.

6B4 proteoglycan/phosphacan, an extracellular variant of receptor-like protein-tyrosine phosphatase zeta/RPTPbeta, binds pleiotrophin/heparin-binding growth-associated molecule (HB-GAM)

A major chondroitin sulfate proteoglycan in the brain, 6B4 proteoglycan/phosphacan, corresponds to the extracellular region of a receptor-like protein-tyrosine phosphatase, PTPzeta/RPTPbeta. Here, we purified and characterized 6B4 proteoglycan-binding proteins from rat brain. From the CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid) extract of brain microsomal fractions, 18-, 28-, and 40-kDa proteins were specifically isolated using 6B4 proteoglycan-Sepharose. N-terminal amino acid sequencing identified the 18-kDa protein as pleiotrophin/heparin-binding growth-associated molecule (HB-GAM). Scatchard analysis of 6B4 proteoglycan-pleiotrophin binding revealed low (Kd = 3 nM) and high (Kd = 0.25 nM) affinity binding sites. Chondroitinase ABC digestion of the proteoglycan decreased the binding affinities to a single value (Kd = 13 nM) without changing the number of binding sites. This suggested the presence of two subpopulations of the proteoglycan with different chondroitin sulfate structures. Heparin potently inhibited binding of 6B4 proteoglycan to pleiotrophin (IC50 = 3.5 ng/ml). Heparan sulfate and chondroitin sulfate C inhibited moderately (IC50 = 150 and 400 ng/ml, respectively), but, in contrast, chondroitin sulfate A and keratan sulfate were poor inhibitors (IC50 > 100 microg/ml). Immunofluorescence and immunoblotting analyses indicated that both 6B4 proteoglycan and PTPzeta are located on cortical neurons. Anti-6B4 proteoglycan antibody added to the culture medium suppressed pleiotrophin-induced neurite outgrowth of cortical neurons. These results suggested that interaction between 6B4 proteoglycan and pleiotrophin is required for the action of pleiotrophin, and chondroitin sulfate chains on 6B4 proteoglycan play regulatory roles in its binding.

Single-copy transgenic mice with chosen-site integration

We describe a general way of introducing transgenes into the mouse germ line for comparing different sequences without the complications of variation in copy number and insertion site. The method uses homologous recombination in embryonic stem (ES) cells to generate mice having a single copy of a transgene integrated into a chosen location in the genome. To test the method, a single copy murine bcl-2 cDNA driven by either a chicken beta-actin promoter or a human beta-actin promoter has been inserted immediately 5' to the X-linked hypoxanthine phosphoribosyltransferase locus by a directly selectable homologous recombination event. The level of expression of the targeted bcl-2 transgene in ES cells is identical in independently isolated homologous recombinants having the same promoter yet varies between the different promoters. In contrast, the expression of bcl-2 transgenes having the same (chicken beta-actin) promoter varies drastically when they are independently integrated at random insertion sites. Both promoters direct broad expression of the single-copy transgene in mice derived from the respective targeted ES cells. In vitro and in vivo, the human beta-actin promoter consistently directed a higher level of transgene expression than the chicken beta-actin promoter.

The role of lipoprotein lipase and apoprotein E in the recognition of chylomicrons and chylomicron remnants by cultured isolated mouse hepatocytes

Lipoprotein lipase (LPL) has been proposed to play a role in the uptake of chylomicron remnants by hepatocytes by mediating the binding of these lipoproteins to cell-surface glycosaminoglycans and to the low-density-lipoprotein receptor-related protein (LRP). This proposal is based on studies that examined the binding of chylomicrons to HepG2 cells, fibroblasts and Chinese hamster ovary cells in culture, in the presence of large amounts of LPL [Beisiegel (1995) Curr. Opin. Lipidol. 6, 117-122]. We have investigated whether LPL attached to the surface of chylomicrons enhances the binding and uptake of these lipoproteins to isolated hepatocytes maintained in culture. Bovine milk LPL was bound to mouse chylomicrons, double-labelled in vivo with [3H]retinol (in retinyl esters) and with [14C]palmitic acid (in triacylglycerols), collected from the mesenteric lymph of normal mice and from mice lacking the apoprotein E (apo E) gene. Normal chylomicrons (containing apo E) and apo E-free chylomicrons, with or without bound LPL, were incubated with cultured hepatocytes isolated from mice lacking the apo E gene. At 0 degree C LPL did not enhance the binding of the normal or apo E-free chylomicrons by the hepatocytes. When incubations were performed at 37 degrees C the triacylglycerols of normal and apo E-free chylomicrons were hydrolysed by LPL and there was a significant uptake of [14C]fatty acids and [3H]retinol by the hepatocytes. The addition of heparin or lactoferrin, a known inhibitor of hepatic uptake of chylomicron remnants, to the incubation medium inhibited the uptake of [3H]retinol, present in the lipoprotein core, but not the uptake of the [14C]fatty acids. We conclude that: (1) LPL attached to chylomicrons in amounts sufficient to effectively hydrolyse their core triacylglycerols does not enhance the binding of these lipoproteins to the surface of isolated hepatocytes; (2) the recognition and uptake of chylomicrons by hepatocytes requires that these lipoproteins be first hydrolysed by LPL; and (3) the uptake of lipolysed chylomicrons (remnants) by hepatocytes does not require the mediation of apo E.

Brain somatostatin depletion by cysteamine attenuates the penile erection induced by serotonergic and dopaminergic, but not by cholinergic, activation in rats

To clarify the role of brain somatostatin in the expression of penile erection, the effects of cysteamine, a somatostatin depletor, on the penile erection induced by serotonergic, cholinergic and dopaminergic stimulants were investigated in rats. Fenfluramine (0.1-10 mg/kg, i.p.), pilocarpine (0.032-3.2 mg/kg, i.p.) and apomorphine (0.01-1 mg/kg, i.p.) induced penile erection in rats, with bell-shaped dose-response curves. Pretreatment with cysteamine (200 mg/kg, s.c.) significantly attenuated the penile erection induced by fenfluramine and apomorphine, but scarcely affected that induced by pilocarpine. Neurochemical measures revealed that cysteamine pretreatment significantly reduced the somatostatin content in all brain regions examined. These results provide the first pharmacological evidence that the brain somatostatin may play an important role in drug-induced penile erection.

Intraocular oxygen tension in eyes with proliferative diabetic retinopathy with and without vitreous

BACKGROUND

Intraocular oxygen tension was measured in the eyes of patients with proliferative diabetic retinopathy with or without vitreous in order to determine local differences in tissue oxygenation in the vitreous cavity before and after vitrectomy.

METHODS

We measured oxygen tension, using polarographic oxygen electrodes, at various intraocular locations in 30 eyes of 29 patients with diabetic traction retinal detachment who were candidates for vitrectomy (pre-vitrectomy group) and 13 eyes of 13 diabetic patients who had previously undergone vitrectomy (post-vitrectomy group).

RESULTS

In the pre-vitrectomy group, oxygen tensions proximal to the neovascularization of the disc and the neovascularization elsewhere were significantly higher than the values obtained at other locations in the vitreous cavity. In the post-vitrectomy group, however, the oxygen tensions at those locations were significantly lower than those in the pre-vitrectomy group. There were no significant differences between the values obtained at any of the measurement locations in the post-vitrectomy eyes.

CONCLUSION

Neovascular tissues in the eyes of diabetic patients demonstrated higher oxygen tensions than non-neovascular tissues. This finding suggests that neovascular issue may compensate for intraocular hypoxia by releasing oxygen from the front. Successful diabetic vitrectomy reduces the activity of the neovascular tissue and equalizes levels of oxygenation in the tissue of the vitreous cavity.