Studies on oogenesis and oviposition in the brown spider Loxosceles intermedia (Araneae: Sicariidae)

Loxosceles intermedia is a poisonous spider that has a wide distribution in southern Brazil, and constitutes a public health problem. In this study, the ovaries of mature females were examined by light and electron microscopy, and by histochemistry. Oocytes at all stages of development were observed in the same area of the mature ovarian wall, surrounded by a basement membrane and a proteic band. They were supported by a group of pedicular cells, which may function as follicular cells. No follicular cell was seen around the oocyte. Mature oocytes pass through the ovarian epithelial wall and are released into the ovarian lumen, covered by a vitelline membrane. The basement membrane and proteic band remain in the ovarian wall. On its way out, the oocyte is coated by proteins that will form the chorion. The presence of different coats throughout oogenesis, and at the time of egg release, is correlated with conditions that indicate fertilization occurs in the uterus lumen during oviposition.     

Histopathological and immunohistological changes in the rabbit lung after experimental exposure to a purified enzyme of Micropolyspora faeni.

Rabbits were exposed intratracheally to enzyme 1, a highly immunogenic esterase isolated from Micropolyspora faeni. A single exposure to active enzyme 1 induced no histologically or immunohistochemically detectable changes in the lungs of experimental animals, while signs of focal interstitial and perivascular inflammatory reactions were evident following a course of three exposures to the enzyme. Interstitial pneumonia with characteristic generalized vasculitis and perivasculitis was produced following seven or nine inoculations. An enzymatically inactive preparation of enzyme 1, even by repeated administration, proved ineffective in eliciting pneumonia. Intracellular antigen within macrophages/histiocytes was demonstrated in the lungs of all experimental animals, including those which had been exposed to inhibited enzyme. Repeated exposure to the enzymatically active preparation resulted in the deposition of immunoglobulin and complement in association with vascular endothelia and in the walls of small- and medium-sized blood vessels; both immunoglobulin and complement could also be demonstrated within macrophages/histiocytes. On the basis of these findings it is concluded that (1) Farmer's lung-like interstitial pneumonia may be produced in rabbits by exposure to a purified, enzymatically active derivative of M. faeni, (2) an important pathogenic principle of the disease may consist in the rapid vascular deposition of immune complexes (type III reaction), and (3) damage by direct enzyme action may prove to contribute significantly in eliciting tissue damage by (an) ancillary mechanism(s) not yet understood.     

Reports of envenomation by brown recluse spiders (Araneae: Sicariidae) outnumber verifications of Loxosceles spiders in Florida

Bites attributed to the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, are frequently reported by medical personnel throughout Florida, whereas the extensive arachnological evidence contradicts the alleged widespread occurrence of Loxosceles spiders in the state. We compared reports of brown recluse spider bites made by medical personnel from a 6-yr Florida poison control center database to the known verifications of Loxosceles spiders from 100 yr of Florida arachnological data. Medical personnel diagnosed 124 brown recluse spider bites from 31 of Florida's 67 counties in 6 yr. In contrast, only 11 finds of approximately 70 Loxosceles spiders have been made in 10 Florida counties in 100 yr. Florida does not have sufficient widespread populations of Loxosceles spiders to warrant consideration of brown recluse spider envenomation as a probable etiology of dermonecrosis. Florida health care would improve if medical personnel would consider the multitude of other etiologies that manifest in dermonecrosis.     

Histopathological alterations in the brain (optic tectum) of the fresh water teleost Channa punctatus in response to acute and subchronic exposure to the pesticide Chlorpyrifos

In the present investigation an attempt was made to assess the toxicity of the organophosphate pesticide Chlorpyrifos (0,0-diethyl-0-3,5,6-trichloro-2-pyridyl phosphorothioate; CPF) on the brain (optic tectum) of the teleost Channa punctatus (Bloch). Fish were exposed to acute (1.5, 3.0, 4.5, 6.0 and 7.5 μl/l) for 24 h and sublethal concentrations of CPF 1.79 μl/l (1/3 of LC₅₀) and 0.538 μl/l (1/10 of LC₅₀) for 3 and 7 days respectively. Several endpoints related to the histoarchitectural profile in the optic tectum were evaluated. Histological examination showed detachment in the superficial zone of the Stratum opticum, Str. marginale due to degeneration of neuronal cells. Spongiosis, congestion, necrosis and appearance of clear areas around the nucleus of mononuclear cells in the lining of the Str. fibrosum grisium superficiale, Str. griseum centrale, Str. album centrale were seen. Granular cells found in the innermost layer of optic tectum, i.e. the Str. periventriculare, were severely degenerated and vacuolized and they migrated toward the Torus semicircularis. The histopathological changes were more pronounced with higher concentrations of CPF. The degree of neurodegeneration found in the deep layers of the optic tectum in higher concentration treatment (6.0 and 7.5 μl/l) was more pronounced. These alterations of the optic tectum affected the functioning of motor coordination of the fish body, because CPF inhibited acetylcholine in neuronal synapses. Due to apoptosis in the superficial zone of the optic tectum, normal visual response was affected. Fish showed microphthalmia (reduced size and eye shrinkage in the eye orbit) because of detachment, necrosis, degeneration and vacuolization in different regions after CPF treatment. This study shows that CPF is highly toxic to fish and affect their population survival in environment.     

A radioautographic study of proliferation in brown fat of the rat after exposure to cold

Radioautographs of the interscapular brown fat of six weeks old animals showed that within 24 hours after cold exposure at 4°–5°C, proliferation increased in endothelium of the already profuse capillary network and also that of arterioles and especially that of venules. This continued at a high level for 48 hours then declined. Extravascular fat precursor cells but not fat cells showed an increased proliferative activity at 48 hours cold exposure which continued until 96 hours. By eight days, adaptation to the cold occurred and proliferative activity was not increased thereafter nor did it occur significantly in animals seven months old. Animals exposed to cold 48 hours, given thymidine-H³, and then returned to a temperature of 23°C for a week or more showed a considerable number of labeled fat cells which presumably were precursor cells when the thymidine-H³ was given. When the interscapular brown fat was denervated on one side, there was no loss of lipid nor increased proliferative activity in the vascular or extravascular cells on that side after 48 hours cold exposure. The normally innervated opposite side, however, had more proliferating cells than usual, especially in the endothelium.     

Histopathological findings in harbour seals (Phoca vitulina) found dead on the German North sea coast

Various organs--lung, trachea, liver, kidney, heart, adrenal gland, skin, spleen, thymus, lymph node, gut, thyroid, spinal cord and brain--were removed from 43 seals at dissections performed on the German North sea coast. The specimens were fixed in formalin and routinely processed for light microscopy. The major pathological findings were Lung: acute congestion with interstitial and intra-alveolar oedema; intra-alveolar haemorrhage; suppurative bronchitis and bronchopneumonia; larvae and adult forms of Parafilaroides gymnurus. Liver: acute congestion; granulomatous lesions and infiltrates of eosinophils; intravascular nematodes. Spleen: varying degrees of atrophy of the white pulp; haemosiderosis; acute congestion of the red pulp. Lymph nodes: varying degrees of atrophy of the lymphatic tissue; long-standing sinus histiocytosis with partial fibrotic obliteration of the lumina; parasitic infiltration, sometimes with the Splendore-Hoeppli phenomenon; germinal centre hyperplasia. Thymus: pronounced atrophy of the lymphatic tissue, particularly in the cortical areas. Thyroid: marked reduction in colloid content. The other organs studied were normal or showed only minor histopathological changes. The morphological findings do not allow definite conclusions to be made about the aetiology and pathogenesis of the illness and death of the seals. However, evidence has been published that the seals' illness is probably due to canine distemper virus. The atrophy of the lymphoreticular tissues is consistent with infection by this virus.     

Immunological reactions to liver-specific membrane lipoprotein (LSP) in experimental autoimmune liver disease in rabbits.

Humoral and cellular immunity to a liver-specific membrane lipoprotein (LSP) was followed in rabbits immunized either with allogenic rabbit LSP (RLSP) or with xenogenic human (HLSP) or bovine (BLSP) antigens. After 4 months of immunization, all rabbits showed histological changes in liver resembling those found in chronic aggressive hepatitis and occasionally also those seen in primary biliary cirrhosis in man. Antibodies reacting to both allogenic as well as xenogenic LSP preparations were found with an enzyme-linked solid phase immunosorbent assay (ELISA) in all immunized rabbits. Lymphocyte transformation tests in unimmunized rabbits showed an occasional response to some of the LSP preparations and a strong response towards an equivalent rabbit kidney preparation (RKSP). After immunization, reactions to LSP preparations increased significantly, while no response to RKSP was observed. The results confirm previous findings and further demonstrate that similar LSP containing preparations from human, bovine and rabbit sources share autoantigenic, liver-specific determinants. In addition, species specific determinants seem to be present in each of the LSP preparations studied.     

Cardiac damage in rodents after exposure to bis(2-chloroethoxy)methane

We report that an environmental agent, bis(2-chloroethoxy)methane (CEM), caused cardiac toxicity in male and female F344 rats and B6C3F1 mice exposed to the chemical by dermal administration at doses of 0, 50, 100, 200, 400 or 600 mg/kg 5 days a week for up to 14 weeks. Treatment-related deaths occurred in 10/10 male and 10/10 female rats at 600 mg/kg, in 2/10 female rats at 400 mg/kg, and in 3/10 female mice at 600 mg/kg. The heart lesions were more severe in rats than mice, and more severe in females than males. In rats, the no-observed-adverse-effect level (NOAEL) for the heart lesions was 200 mg/kg for males and 100 mg/kg for females; in mice, it was more than 600 mg/kg for males and 200 mg/kg for females. Multifocal, widespread vacuolization of the myocytes comprised the main morphological feature of the lesions, and only in rats was it accompanied by mononuclear cell infiltration, myocytic necrosis and atrial thrombosis. Hearts from male rats were immunohistochemically stained for troponin T (cTnT) protein. Loss of cytoplasmic cTnT correlated with histopathological damage only in the 600 mg/kg animals. CEM is metabolized to thiodiglycolic acid, a chemical that causes mitochondrial dysfunction. It is hypothesized that mitochondrial damage leads to the heart toxicity from bis(2-chloroethoxy)methane.     

Plasma lipopolysaccharide-deacylating activity (acyloxyacyl hydrolase) increases after lipopolysaccharide administration to rabbits

Acyloxyacyl hydrolase (AOAH) is a leukocyte enzyme that removes secondary (acyloxyacyl-linked) acyl chains from the lipid A moiety of bacterial lipopolysaccharides (LPS). We now report that the same enzymatic activity is present in normal rabbit plasma and that its activity can be greatly increased by LPS challenge. Intravenous administration of LPS to rabbits resulted in a rapid increase (peaking at 90 minutes, with a mean peak increase of 16-fold) of plasma AOAH activity; the activity then slowly decreased to baseline levels over 24 hours. The plasma AOAH is probably derived, at least in part, from circulating leukocytes, since (a) the AOAH response was significantly diminished in leukopenic rabbits, and (b) incubation of blood or isolated leukocytes with LPS in vitro resulted in increased extracellular AOAH activity. These results indicate that AOAH can appear extracellularly, in plasma, as part of the early response to intravenous LPS challenge. The cellular source(s) and biological role of the plasma enzyme remain to be determined.     

Arachnids submitted as suspected brown recluse spiders (Araneae: Sicariidae): Loxosceles spiders are virtually restricted to their known distributions but are perceived to exist throughout the United States

An Internet offer was made to identify any spider in the United States perceived to be a brown recluse spider, Loxosceles reclusa Gertsch & Mulaik (Sicariidae). In total, 1,773 arachnids from 49 states represented three orders (Araneae, Solifugae, and Opiliones) and the identifiable spiders (Araneae) consisted of 38 families, 88 genera, and 158 recognizable species. Participants from states at least half within the known brown recluse distribution submitted Loxosceles spiders 32- 89% of the time, except Louisiana and Mississippi with no submissions. From 25 of 29 states completely or almost completely outside of the range of Loxosceles spiders, no recluse spiders were submitted. Only two discoveries of brown recluses and two of the worldwide tramp species Loxosceles rufescens (Dufour) were submitted from nonendemic Loxosceles areas. States on distribution margins of brown recluse or other native Loxosceles spiders were intermediate in their Loxosceles submissions. This study showed that 1) the general public perceives brown recluses to occur over wide-ranging areas of the United States; and 2) brown recluses are frequently submitted from endemic states and almost never from nonendemic states, and therefore are virtually limited to their known distributions. This study corroborates opinions that diagnosis of brown recluse spider bites is best restricted to areas historically supporting proven, widespread populations of Loxosceles spiders.     

The lipid peroxidation system in the organism of experimental animals after exposure to cyclic hydrocarbons

The paper presents the results of studies of the amounts of diene conjugates, malonic dialdehyde, and Schiff's bases, which are molecular LPO products in the tissues of the lung, liver, kidney in animals exposed to 4-hour inhalation of cyclic hydrocarbons (pyromellitic dianhydride, durol, pseudocumene, and dioxane-1,4). Exposure to ecotoxicants at concentrations of 10 and 1 mg/m3 was found to result in the accumulation of initial, intermediate, and final molecular LPO products. These changes were recorded only after exposure to pseudocumene and dioxane vapors in a dose of 0.1 mg/m3 and after inhalation of dioxane-1,4 vapors in a dose of 0.01 mg/m3.     

Structural alterations in the rat kidney after acute arsine exposure

The mechanism of arsine (AsH3) toxicity is not completely understood. In this investigation, the toxicity of AsH3 and AsH3-produced hemolytic products was determined in primary culture of renal cortical epithelial cells and in the in situ isolated rat kidney. The objective of this study was to model kidney dysfunction caused by AsH3 exposure. The hypothesis was that unchanged AsH3 and AsH3-produced hemolysate that may contain arsenite (As(III)) as metabolite are both responsible for renal toxicity. Toxicity in isolated cells was determined by 2, 3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxa nilide inner salt (XTT) bioreduction, intracellular potassium (K+), and lactate dehydrogenase (LDH) leakage. Data from XTT bioreduction showed that most toxicity occurred at 1 hour and was independent of the arsenic species. At 4 hours, the observed toxicity depended on the arsenic species and was generated by As(III). In the isolated cells, the As(III)-spiked hemolysate produced similar toxicities with regard to intracellular K and LDH. The AsH3-hemolysate only affected LDH at 1 hour. Unchanged AsH3 was very toxic to the isolated rat kidney. In this system, after 10 minutes exposure to AsH3, the effects of toxicity were observed mainly in the glomerular and peritubular endothelial cells. Tubular epithelial cells also presented early signs of toxicity. The AsH3-hemolysate was not toxic after a 1 -minute exposure. These data suggested that early cytotoxicity caused by unchanged AsH3 results in kidney dysfunction, produced by AsH3, and later by the formation of a hemolysate that may contain As(III). These data may be important in understanding the renal toxic effects after AsH3 intoxication.     

Differential susceptibility to experimental allergic encephalomyelitis (EAE) in genetically defined A+ and A- rabbits

Only one out of 57 A-/A- rabbits immunized with rat or guinea-pig myelin developed clinical signs suggestive of EAE. On the contrary, clinical signs of acute or chronic EAE were found in two thirds of the 102 A+/A+ and A+/A- rabbits immunized in the same way. About one third of the diseased animals had reversible acute EAE, another third died paralysed and the last third developed chronic progressive or relapsing EAE. Incidence and severity of EAE symptoms were positively correlated with age and no significant difference was observed between males and females. Cellular and humoral anti-myelin responses were stronger in A+ than in A- rabbits. Anti-A antibodies, on the contrary, were only detected in A- rabbits. The A+ rabbits did not make Anti-A at any time. Anti-A antibodies increased early, in A- rabbits, after immunization with myelin (11-30 days) and were later replaced by a low, but specific, anti-myelin response (60-90 days). The gene responsible for the susceptibility to EAE is autosomal and dominant over resistance. This gene must be closely linked to the A locus or might be the A gene itself. The low susceptibility of A- rabbits to the disease could be, in this last case, a consequence of the competition between the early anti-A and the normal anti-myelin immune responses, both induced by the injection of myelin.