Biological effects of di-(2-ethylhexyl) phthalate and other phthalic acid esters

Esters of o-phthalic acid are widely distributed in the ecosystem. The phthalate acid esters (PAE's) are used as plasticizers in the manufacture of polyvinylchlorides. They are also used as solvents in certain industrial processes and as vehicles for pesticides. The PAE's are used in enormous quantities for a variety of industrial uses in the formulation of plastics. While there are a number of important PAE's, di-ethylhexyl phthalate has perhaps been used the most extensively in the formulation of plastics used in medical devices and blood bag assemblies. The metabolism, biodistribution and excretion varies to some extent among the various PAE's. There are species differences with respect to the metabolism of the PAE's. The route of administration, and the level and length of exposure, are known to affect the toxicological profile of the various PAE's. There is little evidence of bioaccumulation of the various PAE's, and only at very large doses have there been reports of overt toxicity. Evidence for the carcinogenicity of certain PAE's apparently is related to prolonged exposure to high levels.

Specific mixed disulfide formation with purified bovine cardiac glycogen synthase I and glutathione

Bovine cardiac glycogen-free glycogen synthase I reacts with oxidized glutathione at low temperature to partially inactivate the enzyme. Evidence is presented that a mixed disulfide between glutathione and the enzyme is formed in this reaction. A short incubation of the GSSG-treated enzyme with dithiothreitol restores full enzyme activity. The reaction with GSSG is pH dependent and the product is quite stable at neutral pH. Oxidation of one sulfhydryl group in glycogen synthase is associated with a loss of 60-70% of the enzyme activity. Further modification of protein sulfhydryls has less effect on the enzyme activity. Other low molecular weight disulfides also inactivate glycogen synthase and treatment with [35S]cystine to produce a 40% loss of enzyme activity gave rise to a single major radioactive peptide after cyanogen bromide digestion. Thus the GSSG-mediated inactivation of glycogen synthase apparently occurs through a single reactive sulfhydryl group that forms a mixed disulfide with low molecular weight disulfide molecules. Uridine 5'-diphosphate glucose and glycogen prevent the inactivation of glycogen-free glycogen synthase with GSSG, and glucose 6-phosphate retards the rate of inactivation. Reduction and reactivation of the GSSG-oxidized glycogen synthase is not affected by glycogen and it occurs readily at neutral pH with dithiothreitol, mercaptoethanol, or cysteamine. Oxidation of the reactive sulfhydryl group with GSSG has no effect on the rate of glycogen synthase phosphorylation by the catalytic subunit of cAMP-dependent protein kinase.

Immunohistological studies of the thymus in myasthenia gravis. Correlation with clinical state and thymocyte culture responses

In frozen sections of thymus from 9 out of 12 myasthenia gravis patients, the medulla contained follicles of B lymphocytes with germinal centres showing the same immunofluorescence staining pattern as is seen normally in reactive lymphoid tissues. Only 1 similar follicle was seen in 9 normal thymus samples. There was a positive association between the extent of germinal centres, plasma anti-acetylcholine receptor (AChR) titre, and spontaneous anti-AChR production by thymocytes in vitro. These thymic changes were not universally found, and are thus probably not central to the initiation of myasthenia. Between the follicles, in 9 cases, there was an apparent increase in interdigitating cells with closely associated 'inducer' (OKT4+)T lymphocytes. Thymic antigen presenting cells--either here or in the germinal centres--could be involved in breaking self-tolerance, or in perpetuating the autoimmune response, and it may be their removal that is therapeutic.

Quantitative analysis of Weddell seal (Leptonychotes weddelli) underwater vocalizations at Mcmurdo Sound, Antarctica

The Weddell seal (Leptonychotes weddelli) has a large repertoire of underwater vocalizations. Twelve underwater calls subdivided into 34 call types were classified based on differences in frequency range, duration, repetition rate, number per series, presence or absence of harmonics, auxiliary sound usage, and contour. The repertoire also contains nine dependent auxiliary sounds. In summary, this study standardizes the description and terminology for underwater vocalizations, reports source sound-pressure levels, and reviews usage differences by male and female seals.

MEHP/DEHP: gonadal toxicity and effects on rodent accessory sex organs

The phthalate acid esters (PAEs), and, in particular, di(2-ethylhexyl) phthalate (DEHP) and its monoester, monoethylhexyl phthalate (MEHP), can adversely affect rodent testes but only at high doses. Rat gonadal zinc levels can be decreased by the injection of DEHP, but not MEHP. The rat prostate gland seems to be particularly sensitive to PAE-induced zinc depletion. PAE-induced changes in male reproductive organs were more evident in the rat than in the mouse. Some of the effects of MEHP can be demonstrated in vitro since it can alter the uptake of 65Zn in rodent gonads and accessory sex organs.

Immunological analysis of the skin in graft versus host disease

Immunohistochemical analysis was performed on skin biopsies from patients suffering from graft versus host disease (GVHD) following bone marrow transplantation for aplastic anaemia and leukaemia. Lymphoid cells infiltrating the skin were exclusively T cells with the OKT8+ phenotype and these are probably cytotoxic T cells. Langerhans cells were reduced in number in all specimens and a variable number of HLA-DR positive macrophages were seen in the dermis. In several cases HLA-DR antigens were expressed on keratinocytes. These results show consistent features which may help discriminate rashes in the skin in the post-transplant period.

Induction of metallothionein in the rat brain by copper implantation but not by cobalt implantation

Following gel-filtration of cytosol prepared from copper-implanted rat brain there was a pronounced copper-containing, cadmium-binding peak with a relative elution volume similar to that of hepatic metallothionein (MT). No such peak was apparent in cytosol derived from cobalt- or glass-implanted brains. Spectral analysis of a purified protein from copper-implanted brain reveal a UV absorption spectrum characteristic of MT.

T cell subset abnormalities in tissue lesions developing during autoimmune disorders, viral infection, and graft-vs.-host disease

The authors review a large body of contemporary immunohistologic findings on the tissue distribution of T lymphocytes in normal and pathological conditions. The suggestions for technological advances in this field are: signal amplification using mixtures of monoclonal antibodies directed against different epitopes on the same antigen (e.g. OKT4A+B+D), triple layer amplification systems using hapten-labelled antibodies, and informative double staining methods with combinations of antibodies labelled with different fluorochromes or enzymes. Review of histological observations in a series of human diseases suggests that imbalances of OKT4+ and OKT8+ subsets of T lymphocytes may represent different types of immunoregulatory disorders. Rheumatoid arthritis and sarcoidosis appear to involve a high level of OKT4+ subpopulation response coupled with an associated appearance of a special type of HLA-DR+ macrophages. It remains to be seen whether normal or self-limited immunological responses (early stages of bacterial infection or delayed-type hypersensitivity reactions) produce OKT4+ and macrophage responses that are characteristically different. Meanwhile, excessive levels of OKT8+ cells have been found in a wide range of recognized or presumed immunoregulatory disorders including: graft-vs.-host reaction and viral infections. These disorders, as well as primary biliary cirrhosis and lichen planus, appear to possess both overlapping and disparate clinical characteristics, and the immunohistological observations may reflect the functional heterogeneity of OKT8+ populations in these diseases. These studies show that histologically meaningful heterogeneity can already be demonstrated for the OKT8+ lymphocyte group.

Dephosphorylation of glycogen synthase in rat heart extracts by E. coli alkaline phosphatase. Use of an exogenous phosphatase to study substrate-mediated regulation of dephosphorylation

Regulation of the dephosphorylation of glycogen synthase in extracts from rat heart has been studied by adding exogenous phosphatase to the extract. These experiments were possible only because the endogenous protein phosphatase activity of the extract could be inhibited by KF under conditions where alkaline phosphatase activity was not. The concentration of substrate (glycogen synthase from the heart extract) and catalyst (purified E. coli alkaline phosphatase) could be varied independently, by adding known amounts of alkaline phosphatase to the KF-containing heart extracts. Alkaline phosphatase could completely dephosphorylate glycogen synthase while phosphorylase was unchanged. The rate of dephosphorylation was proportional to both the concentration of alkaline phosphatase added to the tissue extract and the amount of glycogen synthase in the extract. The Km for glycogen synthase was close to the concentration found in heart tissue. The Km and the maximum rate of dephosphorylation were both dependent on the phosphorylation state of the glycogen synthase. Less phosphorylated enzyme forms were dephosphorylated faster. These results indicate the necessity for precise control of many variables in studying the rate of glycogen synthase dephosphorylation. Alkaline phosphatase-catalyzed dephosphorylation could be inhibited by physiological concentrations of glycogen. Glycogen synthase dephosphorylation in extracts from fasted-refed rats was less sensitive to glycogen inhibition than in extracts from normal animals. The phosphorylation state of the glycogen synthase in these animals was assessed by kinetic studies to show that differences in phosphorylation state probably could not account for the observations. Fasting led to a decreased rate of dephosphorylation of glycogen synthase due to both an apparent change in kinetic properties of glycogen synthase as a substrate for alkaline phosphatase, and an increased inhibitory effect of glycogen. Stable modifications of glycogen synthase caused by altered nutritional states in the animals are thought to produce these effects.

Chloroperoxidase halogenation reactions. Chemical versus enzymic halogenating intermediates

In the absence of organic substrates, chloroperoxidase catalyzes the peroxidation of chloride and bromide ion to molecular chlorine and bromine. However, these molecular species are not formed as intermediates in the enzymic halogenation of organic halogen-acceptor substrates. The rate of oxidation of chloride to its respective molecular species is considerably slower than the rate of enzymic chlorination of acceptor substrates. Furthermore, differences are observed in substrate specificities between enzymic and chemical halogenation reactions. Thiourea and methionine are substrates in chloride-dependent oxidation reactions catalyzed by chloroperoxidase and are preferred at least 50:1 and 30:1 respectively over 2- chlorodimedone. Corresponding nonenzymic reaction preferences for the oxidation of thiourea versus 2-chlorodimedone chlorination are only 2:1 with hypochlorite and 3:1 with molecular chlorine. Also, hypochlorite shows essentially no preference for methionine compared with 2-chlorodimedone. In the bromide-dependent reactions catalyzed by chloroperoxidase, bromine is formed at a rate equivalent to that of the bromination of acceptor substrates. However, the specificity of the bromide-dependent oxidation of methionine versus the bromination of 2-chlorodimedone by chloroperoxidase is 4:1. This value is significantly higher than the ratio in reactions of these two substrates with molecular bromine, which is essentially 1:1. A general reaction scheme for all reactions of chloroperoxidase with its halogen-acceptor substrates is proposed. This process involves the initial formation of Compound I and its subsequent conversion into an iron (III) hypohalite halogenating intermediate.

Nuclear terminal deoxynucleotidyl transferase in leukaemic infiltrates of testicular tissue

Early detection of testicular leukaemia and the identification of residual leukaemic cells in treated patients are important aims in the management of males with acute lymphoblastic leukaemia (ALL). In most cases of ALL ( greater than 95%) the blast cells express terminal deoxynucleotidyl transferase (TdT), a nuclear enzyme. We have therefore standardized the immuno-fluorescence and -peroxidase techniques (using anti-Tdt antibodies) for identifying TdT cells in the normal thymus, as well as in samples of testis with heavy leukaemic infiltrates (positive controls). TdT cells can be identified in formalin (but not in Bouin's or Carnoy's) fixed paraffin-embedded tissues, and the preservation of morphological details is excellent. The method is nevertheless difficult to standardize and also requires the use of deoxyribonuclease (DNase) for the digestion of sections. However, in frozen tissue sections, stronger staining of TdT cells was found, even without DNase treatment. Good morphology was preserved when cut sections were fixed immediately in the cryostat. In the second part of the study 15 samples from treated boys were analysed to see whether the technique is suitable to identify residual minimal leukaemic infiltrates. In 5 patients scanty disseminated TdT cells were detected, and in 2 patients small clumps of TdT cells were seen. The results indicate that the immunohistological identification of TdT ALL blasts may be the method of choice.

Health visiting and pre-school children with behavioural problems in the County of South Glamorgan: an exploratory study

This study surveys firstly, using a modified semantic differential technique, how a sample of health visitors in the County of South Glamorgan perceived different behavioural problems in pre-school children. A selection of visiting records, covering a 1-year period, is also studied. Results from the semantic-differential indicate that health visitors perceive eating and sleeping as the most common problem areas. Hyperactivity and sleeping problems are seen as being the most difficult to deal with and the most disruptive to family life. Although health visitors generally feel it is necessary to follow up children with behaviour problems, they find these difficult to resolve. About one third of children are referred to other agencies. Visiting records reveal that children with hyperactivity and sleeping problems receive the highest number of visits from health visitors and that there is little improvement in these children over a period of 1 year. An extension of the health visitor's role and training to include behavioural treatments for pre-school children is discussed.

Combined immunological and histochemical analysis of skin and lymph node lesions in histiocytosis X

The immunological phenotype of the cells involved in skin and lymph node lesions from two cases of histiocytosis X (H-X) were analysed by immunofluorescence techniques using combinations of heterologous and monoclonal antisera to Ia-like antigen and human cortical thymocyte (HTA-1) determinant. These cells were also characterised by a new technique using simultaneous immunofluorescence and enzyme histochemistry for acid phosphatase (ACPase). The major cell type in the lesions was found to express the same Ia+, HTA-1+ phenotype as normal epidermal Langerhans' cells (LC) and was unreactive for ACPase. Additional cell types included Ia-, HTA-1- multinucleate giant cells and residual lymphoid populations. These findings endorse previous concepts that H-X is a proliferation of abnormal LC and emphasise the heterogeneous nature of the cells involved in the disease.

The relationship between T lymphocyte subsets and Ia-like antigen positive nonlymphoid cells in early stages of cutaneous T cell lymphoma

Immunofluorescence studies were carried out in cutaneous T cell lymphoma (mycosis fungoides) in order to analyse the microanatomical relationship of the different T lymphocyte subsets (inducer and suppressor/cytotoxic cell populations) to large nonlymphoid Langerhans-type and so-called "indeterminate" or interdigitating cells. The conventional and mouse (monoclonal) antibodies were used in various combinations using fluorescein and rhodamine labeled second layers. In 5 of the 7 cases studied the dermal infiltrate consisted of numerous T (HuTLA+) lymphocytes, 80-90% of which expressed the inducer phenotype (HuTLA+,OKT4+). Most of these cells formed close contact with large cells exhibiting large amounts of Ia-like antigens. These cells corresponded to the interdigitating and indeterminate cells in the sections. By contrast, only small numbers (10-20%) of T cells of suppressor/cytotoxic type (HuTLA+,OKT8+) were seen. These did not show a close affinity to the Ia-like antigen positive nonlymphoid component but appeared to have a predilection for the epidermis. Epidermal Langerhans cells, also strongly Ia-like antigen positive, were further defined by 2 monoclonal antibodies reacting with a cortical thymocyte antigen HTA-1. Although Langerhans cells are probably related to the Ia-like antigen positive dermal cells only a few of the abundant latter population were HTA-1+. In the remaining 2 cases, larger populations of OKT8+ (suppressor/cytotoxic) cells were seen and could be heralding a particularly benign course. These observations indicate a close functional relationship between the lymphoid and Ia-like antigen positive dermal cells during the pre-malignant phase of cutaneous T cell lymphoma.