The specificity of nematode allergens in the diagnosis of human visceral larva migrans.

Extracts of nematodes have been used as skin test antigens in the diagnosis of nematode infections for many years. Ascaris lumbricoides and Toxocara canis are two nematodes commonly involved in human parasitism, the latter being associated with the clinical condition of Visceral Larva Migrans. In vitro and in vivo experiments reported in this paper confirm experimentally, as well as clinically, the existence of cross-reacting antigens between T. canis and Ascaris spp., and probably between T. canis and other nematodes. These cross-reactions compromise the usefulness of skin tests in the diagnosis of such parasitic infections.     

A unique serine-specific elongation factor Tu found in nematode mitochondria

The translation elongation factor Tu (EF-Tu) delivers aminoacyl-tRNAs to ribosomes by recognizing the tRNA acceptor and T stems. However, the unusual truncation observed in some animal mitochondrial tRNAs seems to prevent recognition by a canonical EF-Tu. For instance, nematode mitochondria contain tRNAs lacking a T or D arm. We recently found an atypical EF-Tu (EF-Tu1) specific for nematode mitochondrial tRNAs that lack the T arm. We have now discovered a second factor, EF-Tu2, which binds only to tRNAs that lack a D arm. EF-Tu2 seems unique in its amino acid specificity because it recognizes the aminoacyl moiety of seryl-tRNAs and the tRNA structure itself. Such EF-Tu evolution might explain tRNA structural divergence in animal mitochondria.     

Two new nematode species found in amphibians and reptiles from the north part of Fergana valley

Two new species of nematodes found, in the north of Fergana Plain (Uzbekistan): Raillietnema uzbekistanica sp. n. (Cosmocercidae) from the Horsfields Tortoise Testudo horstfieldi (Testudinidae), and Spironoura govacus sp. n. (Kathlaniidae) from the green toad Bufo viridis (Bufonidae). Data on infection of R. uzbekistanica sp. n. with predatory fungi in different seasons are given.     

A freeze-fracture study of the surface of the infective-stage larva of the nematode Trichinella

The surface layers of the cuticle of the infective, first-stage larva of the nematodes Trichinella spiralis and T. spiralis var. pseudospiralis have been studied by means of the freeze-fracturing technique. No obvious differences between the two nematodes were found. A double-layered structure covers the cuticle. Its outermost layer consists of particles embedded in an amorphous matrix; its inner layer is composed of a sheet of fine filaments which may be composed of globular subunits. This unique double layered structure is not like a normal cell membrane in structure. The surface of the cuticle beneath it is relatively smooth except for impressions from the inner surface of the double-layered structure. The cuticle surface did not fracture in the manner of a cell membrane.     

Carotenoids found in Littorina littorea and their relationship to parasitic infection by larva trematodes

Littorina littorea from Long Island Sound feed primarily on algae: Chlorophyceae (three species) and Rhodophyceae (two species). Carotenoids from the algae accumulate in tissues of the snail in either an unchanged or a metabolized state. β-Carotene, the major pigment of green and red algae, was isolated from the foot, hepatopancreas, and nephridium of these snails. Six oxygenated carotenoids, not completely identified, were isolated from the same tissues. The snails show a variation in foot color from white to brown to red. L. littorea is parasitized by trematode larvae of Cryptocotyle lingua and Cercaria parvicaudata from which β-carotene and one oxygenated carotenoid were isolated. Contrary to previous work, there is no relation between foot color of the snail and parasitic infection. Neither age nor sex appears to have any relation to foot color. Although carotenoid pigments are known to cause the variation in foot color, the reasons or factors for their accumulation in the snail tissue have not been established. Some hypothetical explanations are discussed.     

Ultrastructure of the tail region of the second stage preparasitic larva of the root-knot nematode

Studies on the tail of second-stage infective larvae (L₂s) of Meloidogyne javanica, M. incognita and M. hapla from a region anterior to the rectal gland to the tail tip have revealed the presence of a previously undescribed sensory organ, the caudal sensory organ, in the posterior region of the tail.The extreme tip of the tail consists of solid cuticle and the different zones of this structure are described throughout the tail region. Longitudinal sections through the anus and rectum have revealed that the cortical (external cortical, epicuticle) layer gradually decreases in thickness until its outermost layer appears to merge with the plasma membrane of the rectal inflation or gland. This gland appears to be similar in all three species studied.The two phasmidial glands and their canals are described from transverse sections. Somatic muscle is first found in the region of the anus and it extends anteriorly throughout most of the length of the L₂. Depressor ani muscles which insert on the dorsal surface of the rectum are also described.The rectal gland in the dilated state occupies about three quarters of the diameter of the L₂. It contains a matrix which resembles that extruded from the adult female rectal gland cells. The rectal gland cells contain large amounts of rough endoplasmic reticulum and desmosomes are found close to the junction of these cells and the plasma membrane of the gland itself. More anteriorly in the L₂ most of the area is taken up by large lipid droplets which function as an energy reserve.It is suggested that the rectal gland should not be used as a taxonomic criterion for separating the La_2^S of Meloidogyne because it can vary so much in appearance within the same species.     

Creating a blood line from human skin

A recent study has generated blood cell progenitors with therapeutic potential by direct lineage conversion of human fibroblasts, thus circumventing reprogramming to pluripotent stem cells.     

In vivo transformation of human skin with human papillomavirus type 11 from condylomata acuminata.

Human papillomaviruses (HPVs) have been implicated in the development of a number of human malignancies, but direct tests of their involvement have not been possible. We describe a system in which human skin from various sites was infected with HPV type 11 (HPV-11) extracted from vulvar condylomata and was grafted beneath the renal capsule of athymic mice. Most of the skin grafts so treated underwent morphological transformation, resulting in the development of condylomata identical to those which occur spontaneously in patients. Foreskins responded with the most vigorous proliferative response to HPV-11. The lesions produced the characteristic intranuclear group-specific antigen of papillomaviruses. Both dot blot and Southern blot analysis of DNA from the lesions revealed the presence of HPV-11 DNA in the transformed grafts. These results demonstrate the first laboratory system for the study of the interaction of human skin with an HPV. The method may be useful in understanding the mechanisms of HPV transformation and replication and is free of the ethical restraints which have impeded study. This system will allow the direct study of factors which permit neoplastic progression of HPV-induced cutaneous lesions in human tissues.     

Characterization of peptides resulting from digestion of human skin elastin with elastase

Several pathological disorders are associated with abnormalities in elastic fibers, which are mainly composed of elastin. Understanding the biochemical basis of such disorders requires information about the primary structure of elastin. Since the acquisition of structural information for elastin is hampered by its extreme insolubility in water or any organic solvent, in this study, human skin elastin was digested with elastase to produce water-soluble peptides. Tandem mass spectrometry (MS/MS) experiments were performed using conventional electrospray ionization (ESI) and nano-ESI techniques coupled with ion trap and quadrupole time-of-flight (qTOF) mass analyzers, respectively. The peptides were identified from the fragment spectra using database searching and/or de novo sequencing. The cleavage sites of the enzyme and, for the first time, the extent and location of proline hydroxylation in human skin elastin were determined. A total of 117 peptides were identified with sequence coverage of 58.8%. It has been observed that 25% of proline residues in the sequenced region are hydroxylated. Elastase cleaves predominantly at the C-terminals of the amino acids Gly, Val, Leu, Ala, and Ile, and to a lesser extent at Phe, Pro, Glu, and Arg. Our results confirm a previous report that human skin elastin lacks amino acid sequences expressed by exon 26A.     

Tail skin of the dipnoan Neoceratodus larva: fine structure and differentiation

The fine structure of the tail skin oflarval Neoceratodusforsteri , between stages 40 and 50 (Kemp, 1982), is described and where applicable specific cellular components are compared and contrasted with comparable ones in the skin of adult dipnoans, teleosts and larval and adult amphibians.
The epidermis of the early developing tail, within the range studied, differentiates a variety of different cell types. Surface epithelial lucent and vacuolated lucent cells and basal cells are distinguished, and goblet (mucous) cells, Merkel cells and macrophages appear in the epidermis towards the end of the series.
Below a poorly developed collagenous basement lamella, immature melanophores with premelanosomes are present, and likewise there are non–myelinated nerves, some striated muscle fibres, capillaries and mesenchymal fibroblasts.
The tail epidermis is innervated by naked neurites from the beginning of the series, and the earliest recognizable Merkel cell is in synaptic association with neurites.     

Heterogeneity of tyrosinases isolated from rat skin, normal human skin, and human melanoma tumors

An electrophoretically homogeneous preparation of tyrosinase (Mr = 61 kDa) was isolated from rat skin. The purification procedure which consisted in chromatographic separation of Triton X-100-solubilized proteins included four main steps, namely: gel filtration, anion-exchange chromatography and two consecutive affinity chromatography steps. Isoelectrofocusing revealed the presence of 9 isoforms possessing an L-DOPA oxidase activity, of which proteins with pI of 4.26 and 4.33 were the major ones. The specific activity of the preparation was 43 nmol/min/mg of protein. Human skin epidermis was practically devoid of the L-DOPA-oxidase activity which was due not only to the absence of tyrosinase but also to the presence of a large amount of a 66 kDa protein able to inhibit the oxidation of L-DOPA to DOPA-chrom. The tyrosinase preparation from human melanoma consisted, predominantly, of two isoforms (48 and 69 kDa) which upon isoelectrofocusing displayed a high heterogeneity at pH around 3-5. The specific activity of the melanoma preparation markedly exceeded that of normal skin tyrosinase and was equal to 290 nmol/min/mg of protein.     

A new design of the Baermann, Moraes, Coutinho's technique for the isolation of nematode larva

We have adapted the Baermann-Moraes-Coutinho's technique and the results have demonstrated that more economy of material and physical space have been obtained becoming easier to work in the laboratory and in the field. The sensitivity of the adapted technique was somewhat higher for Strongyloides stercoralis (2.8%) when compared with the original technique and 6.5% for sedimentation methods.