Alterations in phospholipid biosynthesis by polychlorinated biphenyls and polychlorinated biphenylols

Inhibition and stimulation of synthesis of phospholipids by polychlorinated biphenyls (PCB) have been reported by several authors. The mode of action of PCB on the synthesis of phospholipids has not been determined. Results of experiments in the present report indicate that both PCB and polychlorinated biphenylols alter the activities of key enzymes of glyceride and phospholipid synthesis. 4-Chloro-4-biphenylol (CB-OH), 2',3',4',5,5'-pentachlorobiphenylol (PCB-OH) and 2,4,5,2',4',5'-hexachlorobiphenyl (HCB) inhibited sn-glycerol-3-phosphate acyltransferase activity. Inhibition by PCB-OH was noncompetitive with apparent Ki of 2.6 X 10(-4) M. PCB-OH stimulated phosphatidase activity, but no apparent change was observed with CB-OH. PCB inhibited phosphorylcholine glyceride transferase activity, but had no significant effect on diglyceride acyl transferase.     

Structural and biochemical changes in lungs of 3-methylindole-treated rats.

Effects of a single dose of 3-methylindole (3-MI) (250 mg/kg intraperitoneally) were studied at different times ranging from 12 hours to 2 weeks post-treatment (PT). Microscopic study revealed mild Clara cell injury 24 hours PT and mucus hyperplasia 24 hours to 2 weeks PT. Diffuse type I alveolar epithelial cell necrosis occurred at 48 hours, followed by type II cell hyperplasia. Septal edema and accumulation of interstitial and capillary polymorphonuclear leukocytes and perivascular mixed mononuclear inflammatory cells accompanied the injury and repair. A gradual resolution of lesions with persistent mononuclear inflammatory cellular clusters at septal junctions, focal septal fibrosis, and accumulation of alveolar macrophages was evident at 1 and 2 weeks PT. Collagen, measured as hydroxyproline, in 3-MI-treated rats was significantly increased to 130% and 139% of control (3.0 mg/lung) at 1 and 2 weeks PT, respectively. Biphasic peaks of plasma 6-keto-prostaglandin F1 alpha occurred at 12 to 24 hours and at 96 hours PT with 3-MI and thromboxane B2 was elevated 12, 48, and 96 hours PT. Right ventricular/left ventricular and septal weight was increased to 120% and 140% of the control 1 and 2 weeks PT. We concluded that 3-MI induces alveolar septal injury in the rat with relatively complete repair of the alveolar epithelium and residual mild focal septal fibrosis and pulmonary hypertension 2 weeks PT. Arachidonic acid-derived mediators and inflammation are associated with 3-MI-induced lung injury.     

Dynamics of lymphocyte subsets in children living in an area polluted by polychlorinated biphenyls

Immune system development, particularly in the pre-natal and early post-natal periods, has far-reaching health consequences during childhood, as well as throughout life. Exposure to poly-chlorinated biphenyls (PCBs) during pre-natal and early life has been previously associated with changes in the incidence of infectious and allergic diseases in children, and humoral immunity alterations. Lymphocyte immunophenotyping is an important tool in the diagnosis of immunologic and hematologic disorders. This study used a lysed whole blood method for analysis of lymphocyte sub-populations in samples from children born and living in two districts: a highly-contaminated area (Michalovce) and one (Svidnik/Stropkov) with ≈ 2-fold lower environmental PCB levels. The percentages of B-lymphocytes (CD19(+)), activated HLADR(+)CD19(+) cells, and CD8(+) T-lymphocytes significantly increased at 6- and 16-months-of-age in both selected regions as compared to in cord blood values (p < 0.001). Levels of CD3(+) cells increased significantly (from 61 to 65%) in samples from Michalovce (p < 0.01). Levels of CD4(+) T-lymphocytes declined 10% among 16-month-olds in both regions (Michalovce at p < 0.001 and Svidnik/Stropkov at p < 0.01). Natural killer (NK) cell levels decreased 50% in Michalovce 6- and 16-month-old children and 42% among 6-month-olds in Svidnik/Stropkov (p < 0.001). Compared with the less-contaminated region, Michalovce samples showed significantly higher expression of CD3(+) T-lymphocytes, B-lymphocytes, and activated B-lymphocytes, whereas NK cells were less expressed. Even after adjustment for selected covariates, e.g., maternal cigarette smoking, age, parity, ethnicity, birth weight, and gender of infant, the levels of CD19(+), HLADR(+)CD19(+), and CD3(-)CD(16 + 56)(+) cells were seen to remain significantly different between the districts. These results showed that early-life environmental PCB exposure was associated with fluctuations in major lymphocyte subsets in children, suggesting that there is a post-natal immune system response to PCB exposures.     

Immunohistochemical localization of pepsinogen A and C containing cells in Barrett's oesophagus

Summary No data are available on the localization of Pepsinogen A (PGA=PG I) and Pepsinogen C (PGC=PG II) positive cells in Barrett's epithelium. Endoscopic biopsy specimens were taken from the columnar epithelium from 23 patients (n=93), and in addition from the cardia from eight healthy control subjects (n=38). The tissue was stained by the immunoperoxidase technique with specific anti-pepsinogen antisera, and double immunostained for PGA and PGC. In the Barrett's epithelium PGA was found in 28 out of 93 biopsy specimens (30.1%) and PGC in 55 out of 93 (59.1%). Chief cells always stained both for PGA and PGC, while clear mucous cells were often PGA– and PGC+. PGA+ and PGC+ cells were found each in 100% of the biopsy specimens with fundic type epithelium, in 21.7% and 70.7% of biopsy specimens with junctional type, in 0% and 26.1% of biopsy specimens with specialized epithelium and in 12.5% and 43.5% of biopsy specimens with mixed junctional/specialized features respectively. Dysplastic epithelium stained always negatively with both anti-pepsinogen antisera. In most control cardia biopsy specimens PGA as well as PGC were demonstrable; occasionally clear mucous glands were PGA– and PGC+.It is concluded that pepsinogen-containing cells can be accurately identified in the Barrett's epithelium; their presence seems related to the histological cell type. Identification of pepsinogen positive cells may contribute to a more accurate morphological classification of the Barrett's epithelium.Presented in part at the Annual Meeting of the American Gastroenterological Association, San Francisco, May 1986     

Immunohistochemical localization of carbonic anhydrase isozymes in the rat carotid body

The rat carotid body was immunohistochemically stained for carbonic anhydrase I, II and III (CA-I, CA-II and CA-III). Immunoreactivity for CA-I was distributed in type I cells, type II cells and nerve bundles. Smooth muscle cells and endothelial cells of blood vessels were also strongly stained for CA-I. CA-II immunoreactivity was distinctly positive in type I cells and nerve bundles. Vascular smooth muscle cells were weakly positive, and type II cells were negative for CA-II. CA-III immunoreactivity was identified in type I cells and vascular smooth muscle cells. Our results suggest that carbonic anhydrase isozymes in type I cells play an important role in chemoreception for hypercapnia. Immunoreactivities for CA-I and CA-II in the nerve fibres may participate in the synergic action of carotid sinus nerve between hypoxic and hypercapnic stimuli.     

Determination of polychlorinated biphenyls in human blood by solid-phase extraction including on-column lipid decomposition

A method for the isolation of polychlorinated biphenyls (PCBs) from human blood using solid-phase extraction (SPE) has been developed. The procedure incorporates decomposition of lipids by concentrated sulphuric acid directly on the SPE column. Conditions for transferring PCBs onto the SPE column and washing the decomposed blood components from the SPE column were optimised. After clean-up the extracts were analysed using gas chromatography with electron capture detection. An average recovery of PCBs from spiked blood samples was about 78+/-8% and an average precision was about 109+/-7%. Quantitation has been done using four internal standards and calibration curves based on five concentration levels. Low procedural blanks made it possible to determine PCBs in blood quantitatively at a level down to 2-10 pg g(-1). The integrated method for blood is fast, less laborious than methods using liquid-liquid extraction and has a low consumption of organic solvents.     

Cytogenetic analysis of peripheral blood lymphocytes in workers occupationally exposed to polychlorinated biphenyls.

The ability of polychlorinated biphenyls (PCBs) to induce chromosome aberrations and sister chromatid exchanges (SCE) in peripheral lymphocytes was studied in a group of workers occupationally exposed to PCBs during the production of the Czechoslovak PCB products Delor 103 and Delor 106. The effect of PCB exposure was compared between an exposed group (N = 32, 3.25 +/- 0.34% aberrant cells, AB.C.), control group 1 (N = 20, 1.30 +/- 0.29% AB.C.), and control group 2 (N = 20, 1.60 +/- 0.31% AB.C.). The length of PCB exposure over 10 yr increased the frequency of AB.C. in a group exposed for 11-15 yr to 3.40% (N = 5) and in a group exposed for 16-25 yr to 5.85% (N = 7) vs. an increase of 1.60% AB.C. in group C2 and of SCE to 12.6 +/- 0.9/cell vs. 6.9 +/- 0.7 SCE/cell in C2. The clastogenic activity observed in this group may be the result of a high PCB concentration in blood plasma (320 +/- 190 micrograms PCB/l), and it is probably related to its solubility in adipose tissue, when it may act as another mutagen and carcinogen biotransformation inducer.     

Immunohistochemical studies on the development of cells containing progastricsin (minor pepsinogen) in comparison to prochymosin and pepsinogen in bovine abomasal mucosa

The localization of progastricsin was studied in cells of abomasal mucosa from cattle of different ages and feeding regimes and compared to the localization of prochymosin and pepsinogen in the same material by use of an immunofluorescence technique with specific rabbit antibodies. Immunoreactivity for progastricsin was first found in calves at the age of about 45 days in surface mucous cells in the pit of the fundic gland. In older calves and adults, mucous neck cells also produced progastricsin. In the pyloric mucosa, on the other hand, traces of progastricsin immunoreactivity were found in the lower base of the pyloric gland even in newborn calves. When the calves grew older, progastricsin-immunoreactive cells also developed in the pit and later in the neck of the pyloric gland; and the number of these cells in this region increased with age. The development of progastricsin-producing cells seemed to be influenced only by age and not by the feeding of milk to the calves. The ontogeny of progastricsin, prochymosin, and pepsinogen exhibited an interesting pattern in cattle, as they started to be produced at three different ages and gave three different patterns of development in the cells of abomasal mucosa. The number of cells producing prochymosin was closely correlated with milk-feeding, while the development of progastricsin was most related to the age of the calf. The most stable factor during the development of the cells in the abomasum was the number of cells producing pepsinogen.     

Fine structural lesions and hormonal alterations in thyroid glands of perinatal rats exposed in utero and by the milk to polychlorinated biphenyls.

Polychlorinated biphenyls (PCB) produced ultrastructural lesions of thyroid follicular cells and a reduction in serum levels of thyroid hormones in neonatal (0, 7, 14, and 21 days of age) Osborne-Mendel rats exposed to 50 or 500 ppm PCB in utero and by the milk. Litter size was decreased significantly in rats fed 500 ppm PCB. Body weights at 21 days of age were reduced in rats exposed to 50 and 500 ppm PCB. The ultrastructural lesions in follicular cells were dose- and age-dependent but were less extensive than in adult rats of the same strain. At all ages the lesions in thyroid follicular cells were characterized by increased development of rough endoplasmic reticulum and vacuolization of mitochondria. There was an increase of colloid droplets and lysosomes in the older age groups (14 and 21 days) but little evidence for colloid droplet-lysosome interaction necessary for the secretion of thyroid hormones. Shortening of microvilli, with the formation of club-shaped or branching forms, was observed only in 21-day-old rat pups. These ultrastructural alterations in follicular cells exposed to PCB were associated with a significant reduction in serum thyroxine in the rats at birth and at 7, 14, and 21 days of age. Serum triiodothyronine was reduced significantly in 7- and 14-day-old rat pups. The ultrastructural alterations in follicular cells appeared to contribute to the significant lowering of serum thyroid hormone levels in 14- and 21-day-old rats exposed to PCB. These findings suggest that alterations in thyroid structure and function may be important in the pathogenesis of certain metabolic disorders associated with PCB intoxication.     

Experimental silicosis: morphologic and biochemical abnormalities produced by intratracheal instillation of quartz into guinea pig lungs.

Six months after intratracheal instillation of silica, histologic, ultrastructural, cytologic, and biochemical studies were performed on the lungs of guinea pigs. The tissue response consisted of both diffuse alveolar septal infiltration with interstitial fibrosis and granulomatous infiltration with nodular fibrosis. Ultrastructural studies confirmed the presence of a mixed inflammatory exudate in the alveolar interstitium (histiocytes, neutrophils, eosinophils, and lymphocytes) and the Type II lining of cell hyperplasia. The number of lung cells recovered by lavage and the proportions of neutrophils and multinucleated cells in bronchoalveolar cells were significantly greater in experimental animals (P < .05) than in controls (intratracheal saline). Total lung collagen and collagen synthesis by cultured lung tissue were also increased in the experimental animals. Since the response of guinea pig lung to intratracheal silica included pathologic features common to human silicosis and idiopathic pulmonary fibrosis, this model has the potential for improving our understanding of both of these important clinical disorders.     

Immunohistochemical localization of phospholipase C isozymes in mature and developing gerbil cochlea

The possibility that phospholipase C contributes to intracellular signaling in the cochlea was investigated by immunostaining for eight different isoforms of the enzyme. In the mature gerbil cochlea, expression of the isozymes varied widely among different cell types. The phospholipase C-beta1 isoform was detected in inner and outer hair cells, and spiral ganglion neurons where it may participate in regulating Ca(2+) flux. The beta3 isozyme was expressed in epithelial cells thought to mediate lateral and medial circulation of potassium. The beta2 isozyme was present in border, inner phalangeal and Hensen cells, the stria vascularis, and suprastrial and supralimbal fibrocytes where it also may be involved in regulating ion transport activities. The phospholipase C-gamma isozymes were expressed in supporting cells, the stria vascularis, and certain fibrocytes where they possibly participate in activating tyrosine kinase and modulating ion conductances. The delta2 isoform was found in pillar, outer sulcus and strial marginal cells as well as spiral ganglion neurons and their radial processes.Documentation of changes in the expression pattern of phospholipase C isoforms during postnatal development and knowledge of their distribution in several positive control tissues provided further data for speculation about the biologic significance of the cochlear reactivity. The results demonstrate a wide diversity of isozyme distribution in the cochlea and suggest that the enzymes affect activities of various cochlear cell types in different ways.     

Enhancement of amyloid induction by amyloid fibril fragments in hamster

An extract (fibril amyloid-enhancing factor) prepared by sonication of a suspension of water-purified hamster AA-amyloid fibrils showed an amyloid-enhancing effect upon intraperitoneal injection into hamsters. The fibril amyloid-enhancing factor was identical to the original fibrils according to the results of infrared spectroscopy, gel filtration, gel electrophoresis, and Western blotting; although lyophilized samples of the extract did not show any green birefringence after staining with Congo red. From these results, it was concluded that fibril amyloid-enhancing factor represents small fragments of amyloid fibrils which enhance in vivo formation of amyloid fibrils.     

Measurement method for hydroxylated polychlorinated biphenyls in the blood of Yusho patients by liquid chromatography-electrospray tandem mass spectrometry

Hydroxylated polychlorinated biphenyls (OH-PCBs) are formed as major metabolites of PCBs by cytochrome P450 enzyme-mediated oxidation. It has been reported that their total concentration in serum samples of Yusho patients ranged from 390 to 1300 pg/g. We developed a measurement method for OH-PCBs in blood samples by LC/MS/MS. This method is effective at determining the concentrations of PCDDs, PCDFs, Co-PCBs and OH-PCBs from the same sample without special treatment of the sample. The concentration of OH-PCBs in the blood of Yusho patients was examined using this method. The major OH-PCB metabolites were 4-OH-CB187 (54-906 pg/g-wet), 4-OH-CB146 + 3-OH-CB153 (32-527 pg/g-wet), 4-OH-CB109 (ND-229 pg/g-wet) and 4'-OH-CB172 (ND-143 pg/g-wet). The total OH-PCBs ranged from 95 to 1740 pg/g-wet.