Self-interaction of dynein from Tetrahymena cilia

The molecular mass (Mr) and enzymic activity of the larger dynein species from Tetrahymena thermophila has been studied in the high (600 mM) to low (40 mM) ionic strength range. The apparent Mr is found to vary with both ionic strength (by sedimentation velocity and quasi elastic light scattering analysis) and with protein concentration at low ionic strength (by sedimentation equilibrium analysis). These data indicate a strong self-interaction, resulting in dimer formation under low salt conditions. There is no evidence for the formation of species of higher than dimeric mass. A molecular mass for the dynein monomer of 1.64 x 10(6) daltons has been determined, a value rather lower than previous published estimates. The ATPase activity of dynein increases with increasing ionic strength. The possible relationship between this effect and the self-association phenomenon is discussed.

Changes in the rate of crypt epithelial cell proliferation and mucosal morphology induced by a T-cell-mediated response in human small intestine

The rate of crypt epithelial cell proliferation and mucosal morphology have been studied in vitro in explants of fetal human small intestine in organ culture in which a cell-mediated immune response has been elicited by stimulating lamina propria T cells with pokeweed mitogen or monoclonal anti-CD3 antibodies. Twelve hours after the addition of anti-CD3 or pokeweed mitogen, most lamina propria T cells expressed CD25. By 18 and 24 h after the addition of anti-CD3, there were significantly more crypt cells in the cell cycle than in controls, although villus height and crypt depth are the same in both groups. After 3 days, by dissecting microscopy, the villi appeared shorter in cultures in which the T cells were stimulated than in control cultures, and the mucosal surface was obscured by a layer of extruded enterocytes. Villus atrophy was confirmed by direct measurement of Feulgen-stained, microdissected villi. Crypts were longer in T-cell-stimulated cultures, and the rate of crypt epithelial cell proliferation measured by metaphase arrest was increased 10-fold. By electron microscopy, the microvilli and cellular morphology of the surface enterocytes were normal in T-cell-stimulated cultures. These experiments clearly show that a profound immune-mediated crypt epithelial cell hyperplasia can occur in the absence of damage to surface enterocytes.

Necator americanus in the mouse: histopathological changes associated with the passage of larvae through the lungs of mice exposed to primary and secondary infection

The mouse/Necator americanus model was studied to assess the histopathological changes that occur in the lungs following primary and secondary exposure to infective larvae. Groups of BALB/c mice were infected percutaneously and killed on various days post infection. Parasite numbers were counted, the bronchoalveolar leukocyte response was quantified and histological sections of lung material were examined for evidence of host protective inflammatory reactions. An increase in the inflammatory infiltration was observed between days 5 and 9 in both primary and secondary infections but was considerably more intense in re-infected animals. This involved a marked change in the character of the infiltrate, particularly in the number of eosinophils that were recovered in lavage fluid. More worms were trapped in the lungs of challenged mice, as assessed through their inability to escape from lung material incubated in vitro. Overall, the results were found to be compatible with the development of acquired resistance to N. americanus and the expression of host protective immunity during the development of challenge-infection larvae in the lungs.

Morphological integrity of the bronchial epithelium in mild asthma

In severe asthma bronchial epithelial cells are damaged and detached, and it has been proposed that such damage might lead to the bronchial hyperresponsiveness that characterises asthma. To investigate the relation between airway hyperresponsiveness and epithelial damage, biopsy specimens of the bronchial mucus membrane were obtained at fibreoptic bronchoscopy from 11 patients with mild atopic asthma and airway hyperresponsiveness (provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) less than 1.0 mg/ml), and from 17 healthy non-atopic subjects who did not have airway hyperresponsiveness (PC20 methacholine greater than 8.0 mg/ml). Observers who were blind to the presence or absence of asthma examined the biopsy specimens by light and electron microscopy. Epithelial cells, intercellular spaces, and goblet cells were counted. Intercellular junctional complexes were examined, and a semiquantitative assessment was made of ciliary loss, non-parallel central ciliary filaments, and vacuoles in ciliated cells. There were no differences between the asthmatic and healthy groups in any of these measurements. These findings indicate that airway hyperresponsiveness may be present when there is no apparent change in the structure of the bronchial epithelium.

N-phenyl-2-pyridinecarbothioamides as gastric mucosal protectants

A series of substituted 2-pyridinecarbothioamides was synthesized and evaluated for gastric mucosal protectant activity in the rat. Out of this investigation N-(3,5-difluorophenyl)-2- pyridinecarbothioamide (23, AY-31,574) was identified. This compound was much more potent than sucralfate and ranitidine against ethanol-induced lesions. Compound 23 was equipotent with ranitidine against gastric injury caused by stress. Unlike ranitidine, 23 was found to be devoid of antisecretory activity in the pylorus-ligated rat model, making it a selective mucosal protectant. Such a potent selective mucosal protectant may provide a novel clinical approach in treating ulcers.

Peptides related to alpha-melanocyte-stimulating hormone are commonly produced by human pituitary corticotroph adenomas: no relationship with pars intermedia origin

The presence of immunoreactive (ir)-alpha-MSH has been investigated by immunocytochemistry in 24 pituitary adenomas and one case of corticotroph hyperplasia causing Cushing's disease, in four adenomas causing Nelson's syndrome, and in ten 'silent' corticotroph adenomas. It was found that a high proportion of these adenomas have a population of cells containing ir-alpha-MSH in addition to ir-ACTH. In some instances, these adenomas were clearly not associated with the residual intermediate lobe of the pituitary. Radioimmunoassay of plasma from patients with Cushing's disease or Nelson's syndrome showed elevated levels of ir-alpha-MSH in the majority of cases. Characterization of the ir-alpha-MSH in adenoma cells by immunocytochemistry, using an antiserum selective for acetylated forms of alpha-MSH, suggested that only the desacetyl form was present in each case examined. High-performance liquid chromatography of adenoma tissue extracts revealed material co-eluting with acetylated forms of alpha-MSH in only one of six cases. These results have been compared with corticotroph adenomas in animal pituitary glands, and it is concluded that the presence of alpha-MSH peptides cannot be used as a marker for intermediate lobe tumours, and that desacetyl alpha-MSH is commonly produced by corticotroph adenomas.

Defining parameters for peripheral laser angioplasty

In vitro studies are reported using a Pulsed Dye laser at wavelengths of 440, 480, 504, 560 and 590 nm, to vaporise multiple samples of yellow, fibrous and calcified plaque. The threshold for crater production at 440 nm was 5 mJ/pulse and at 590 nm 65 mJ/pulse. Crater depth was significantly deeper at the short wavelengths (440, 480 and 504 nm) than at the longer (560 and 590 nm). Light microscopy confirmed the absence of thermal damage associated with continuous wave lasers. Electron microscopy revealed smooth-contoured craters and no disruption of subcellular elements at the crater margin. Samples of thrombus- and atheroma-occluded human femoral artery were successfully recanalised at the 480 nm wavelength with atraumatic spherical-tipped and modified spherical tipped optical fibres. The advantages of pulsed laser energy in peripheral vessel recanalisation are discussed.

Characterisation and cellular localisation of the immunodominant 47-Kda antigen of Candida albicans

The 47-Kda component of Candida albicans is an immunodominant antigen in the serology of systemic candidosis. Immuno-electronmicroscopy with an affinity-purified antibody to the 47-Kda antigen showed that it was present in the cytoplasm and cell wall of both yeast and mycelial cells. It was found in discrete areas on the inner and outer borders of the cell wall and was mainly located within the wall rather than exposed on the outer surface. Sometimes it appeared to be in channels across the cell wall. In the cytoplasm, it was usually near the cytoplasmic membrane and occasionally appeared in vesicular areas. It was not detected in the nucleus or mitochondria. The 47-Kda antigen did not bind to Concanavalin A, and antigenicity was lost after protease digestion. Peptide mapping suggested that the antigen was highly conserved between different strains of C. albicans.

Acquired resistance to the human hookworm Necator americanus in mice

BALB/c mice were exposed to primary or secondary infection with the hamster-adapted strain of Necator americanus, and the course of infection was monitored through worm recovery and immunological assays. Significantly fewer viable larvae were recovered from the skin site of reinfected mice on day 2 post-infection, and fewer larvae resided in the lungs of challenged mice 3-5 days after infection, suggesting that the skin was involved in resistance to secondary infection. The serum antibody response to L3 antigen was enhanced during secondary infection, peaking on day 9, and the bronchoalveolar leucocyte (BAL) response was more intense at this stage. Thus the secondary BAL response was initiated more promptly than the primary response, peaking on day 13 at twice the intensity of the primary response and five times above the resting level. Differential counts revealed that by far the most significant changes in cell populations were those observed for eosinophils in lavage fluid. At the peak of the response a 925-fold increase over control levels was detected in mice undergoing a challenge infection. Some cellular and serological components of the secondary response were defined in the present work and it was concluded that reinfected mice have the capacity to trap parasites during their passage through the skin and development in the lungs.

Ultrastructural localization of antigens recognized by the monoclonal antibodies MB1, MB2, MT1, UCHL1, and TAL 1B5

In this study the ultrastructural localization of antigens recognized by novel antibodies that allow the recognition of lymphoid antigens in conventionally fixed and wax-embedded sections was investigated. MT1, MB1, and UCHL1 recognize antibodies restricted to the cell membrane, whereas the antigen recognized by MB2 is present only in the cytoplasm. These distributions are different from that of immunoreactivity with TAL 1B5 (anti-HLA DR), which is present both on the cell membrane and in the cytoplasm. The significance of these findings is discussed.

Ovarian neoplasms, functional ovarian cysts, and oral contraceptives

The incidence of ovarian neoplasms and functional ovarian cysts diagnosed at laparotomy or laparoscopy among the 17,000 women taking part in the Oxford Family Planning Association contraceptive study was investigated. Epithelial cancer of the ovary was only 25% as common among those who had ever taken oral contraceptives as those who had never done so (95% confidence interval 8% to 67%). There was little evidence of any important association between use of oral contraceptives and benign teratoma or cystadenoma. Functional cysts of the ovary occurred much less commonly in women who had recently (in the six months preceding diagnosis) taken combined oral contraceptives (but not in those who had taken progestogen only oral contraceptives) than in those who had never taken oral contraceptives or had taken them in the past. This protective effect was more pronounced for corpus luteum cysts (78% reduction; 95% confidence interval 47% to 93%) than for follicular cysts (49% reduction; 95% confidence interval 20% to 70%). It is estimated that about 28 (95% confidence interval 16 to 35) operations for functional ovarian cysts are avoided among every 100,000 women who take oral contraceptives each year.

The recognition of antigens on the surface of adult and L4 Necator americanus by human and hamster post-infection sera

The surface antigens of adult Necator americanus were recognized by post-infection hamster sera and resolved at molecular weight 93,000, 67,000, 46,000, 43,000, 32,000 and 25,000. L4 larvae in contrast had one major surface antigen, resolving at 93,000. These antigens were also recognized by a range of human sera, although on a differential basis. This suggests that the human sera tion. However, the results do indicate that the hamster model might be of immunological relevance to the human disease state, in that infected hamster recognized the full cuticular antigen spectrum of adult Necator. This, at least, gives the experimenter a convenient reference point from which to conduct further experiments incorporating parameters such as re-infection, anthelmintic treatment and genetic variability to study the effect of these modifications on the serological response.

Brown adipose tissue: contributions of nature and nurture to the obesity of an obese mutant mouse (ob/ob)

The aim of this investigation was to compare the contributions of the genotype of the brown adipose tissue (BAT) and of its environment to the obesity of the mutant mouse C57 BL/6J ob/ob. Pieces of interscapular BAT from lean or obese mice were transplanted to a site underneath the kidney capsule of recipient lean or obese mice. The grafts were left in place for 6 to 12 weeks and then examined by histological methods by electron microscopy to examine the ultrastructure of the mitochondria and by fluorescence histochemistry to examine the catecholaminergic innervation of the grafts. When lean BAT was grafted into obese mice, or when obese BAT was grafted into lean mice, kept at ambient temperatures, the characteristics of the donor BAT (i.e. lipid droplet size, mitochondrial ultrastructure and catecholaminergic innervation) transformed partially, but not completely, towards those of BAT in the host mouse. However, if lean mice containing obese BAT grafts were cold-acclimated at 4 degrees C or obese mice containing lean BAT grafts were warm-acclimated at 33 degrees C, the characteristics of the donor BAT transformed completely towards those of the BAT in the host mouse. This complete transformation occurred even if the host mice were returned to 23 degrees C after the period of temperature acclimation. Fluorescent histochemical observations indicated that the sympathetic innervation of BAT grafts was only indistinguishable from that of the lean or obese host BAT when the mice received a period of temperature acclimation (cold for lean mice; warm for obese mice). We conclude that BAT grafts from lean mice can assume the typical characteristics of BAT in obese hosts and that BAT grafts from obese mice can assume the typical characteristics of BAT in lean hosts provided that both the sympathetic innervation and the vascularization of the grafts is the same as in the host. Intrinsic properties of BAT in genetically obese mice are therefore unlikely to be of paramount importance in determining the obesity of the ob/ob mouse. Our results support the conclusions of other workers in implicating the low activity of the sympathetic innervation of BAT as being crucially important in causing the reduction of thermogenic activity.