ELNES study of chemical solution deposited SrO(SrTiO(3))(n) Ruddlesden-Popper films: experiment and simulation.

This article analyzes electron energy-loss near-edge fine structures of the SrO(SrTiO(3))(n=1) Ruddlesden-Popper system and of the parent compounds SrTiO(3) and SrO by comparison with first principles calculations. For that, the fine structures of chemical solution deposited Ruddlesden-Popper films have been experimentally recorded by means of transmission electron microscopy. Moreover, density of states computations using an all-electron density-functional code have been performed. It is shown that the appearance and shape of the experimental O-K and Ti-L(2,3) fine structure features result from the crystallography-dependent electronic structure of the investigated oxides, which display technologically interesting dielectric as well as lattice-structural properties.

Switching Ti valence in SrTiO3 by a dc electric field.

A (001) SrTiO3 wafer has been investigated in situ at room temperature under application of a static electric field of varying polarity by fluorescence x-ray absorption near edge structure (XANES) analysis at the Sr-K and Ti-K absorption edges. The XANES spectra show a clear shift of the Ti-K absorption edge energy. The shift is attributed to a change of the Ti valence state in a volume invoked by diffusion of the oxygen ions and vacancies. No shift was observed for the Sr-K absorption edge energy. Theoretical calculations support these findings.

Spontaneous heterosis in larval life-history traits of hemiclonal frog hybrids.

European water frog hybrids Rana esculenta (Rana ridibunda x Rana lessonae) reproduce hemiclonally, transmitting only their ridibunda genome to gametes. We compared fitness-related larval life-history traits of natural R. esculenta from Poland with those of the two sympatric parental species and of newly generated F1 hybrids. Compared with either parental species, F1 hybrid offspring had higher survival, higher early growth rates, a more advanced developmental stage by day 49, and earlier metamorphosis, but similar mass at metamorphosis. R. esculenta from natural lineages had trait values intermediate between those of F1 offspring and of the two parental species. The data support earlier observations on natural R. esculenta that had faster larval growth, earlier metamorphosis, and higher resistance to hypoxic conditions compared with either parental species. Observing larval heterosis in F1 hybrids in survival, growth rate, and time to metamorphosis, however, at an even higher degree than in hybrids from natural lineages, demonstrates that heterosis is spontaneous and results from hybridity per se rather than from subsequent interclonal selection; in natural lineages the effects of hybridity and of clonal history are confounded. This is compelling evidence for spontaneous heterosis in hybrid clonals. Results on hemiclonal fish hybrids (Poeciliopsis) showed no spontaneous heterosis; thus, our frog data are not applicable to all hybrid clonals. Our data do show, however, that heterosis is an important potential source for the extensively observed ecological success of hybrid clonals. We suggest that heterosis and interclonal selection together shape fitness of natural R. esculenta lineages.

Much ado about doing nothing.

Negative stereotypes about certain kinds of medical specialists are commonly expressed by physicians in the presence of medical students. The authors of this brief essay, an academic pathologist and an academic internist, suggest that these sorts of remarks may have a range of deleterious effects on students. We wish to sensitize medical school faculty to this problem. Moreover, we propose that in an era in which a team approach to patient care is often required, the promotion of positive doctor-doctor relationships is critical and should be an integral part of medical education.

"No pictures from summer vacation": portrayals of pathologists in the printed media.

Public perceptions of pathologists can be shaped by individuals' direct contacts with these medical specialists, as well as by portrayals of them in the media. Few lay people, whether healthy or ill, have direct professional interaction with pathologists. Accordingly, media portrayals can assume great importance in shaping public views of pathologists and their profession. This report discusses how pathologists and the specialty of pathology are depicted in newspaper articles.

Syphilitic cervicitis simulating stage II cervical cancer. Report of two cases with cytologic findings.

Two women, ages 42 and 46, each had a cervical mass that clinically was grossly compatible with invasive carcinoma. Colposcopy supported the clinical impression. Weeks after the women were examined, it was determined that the masses represented syphilitic cervicitis. This entity has received almost no attention in the cytology literature, and is not discussed in major cytopathology texts. Accordingly, the cervicovaginal smears that were obtained in these cases are of interest. The smear pattern, which included lymphocytes, plasma cells, histiocytes, and debris, is described. Although in contrast, the histopathology of syphilitic cervicitis is well-characterized, diagnostic evidence of syphilis was missed in the initial interpretation of several of the biopsies. Syphilis recently has reemerged as a public health problem. Although the cases reported here represent rare events, pathologists should be aware that syphilitic cervicitis may clinically and colposcopically simulate a primary advanced cervical cancer. When interpreting cervical biopsies and cervicovaginal smears, they should be alert to patterns that suggest that syphilis is present.

Granulomatous inflammation related to amyloid deposition in a focus of multiple myeloma. Report of a case with diagnosis by fine needle aspiration biopsy.

A 61-year-old man with no prior history of serious illness presented with a lytic rib lesion. The radiographic differential diagnosis included multiple myeloma, a metastasis and a focal infectious process, such as tuberculosis or actinomycosis. Fine needle aspiration biopsy of the mass yielded an unusual smear pattern that included small lymphocytes, plasma cells, multinucleate giant cells, granulomas and amorphous eosinophilic material. These seemingly unrelated elements suggested the possibility of a chronic inflammatory lesion of bone, such as osteomyelitis, but ultimately proved to represent multiple myeloma with granulomatous inflammation related to amyloid deposition. The case demonstrates that the differential diagnosis of chronic granulomatous inflammation with numerous plasma cells, in the appropriate clinical context, includes amyloid in association with a plasma cell dyscrasia.

Lymphangioma presenting as a primary parotid neoplasm in an adult. Report of a case with the diagnosis suggested by fine needle aspiration biopsy.

A 38-year-old man presented with a unilateral, asymptomatic parotid gland mass. A fine needle aspiration biopsy of the mass, consisting predominantly of small lymphocytes, suggested the possibility of a lymphangioma. Microscopic examination of the subsequent parotidectomy specimen revealed a cystic lymphangioma involving the parotid gland and periparotid soft tissue. Although the presentation of a lymphangioma as a primary parotid neoplasm in an adult is a rare event, the differential diagnosis of a parotid gland aspirate containing small lymphocytes should include a lymphangioma.

Loss of antigens associated with the apical endocytotic pathway in proximal tubules from rats with heymann nephritis.

In addition to the glomerular lesions associated with Heymann nephritis, a rat model of human membranous nephritis, proximal tubule damage, and a perturbation of proximal tubule function also have been reported to occur in this disease. The aim of the present study was to examine in more detail the nature of the apical plasma membrane damage in proximal tubules using specific antibodies directed against clathrin, gp330, and a proton-pumping adenosine triphosphatase, all of which are components of the apical endocytotic apparatus of these epithelial cells. Immunocytochemical studies revealed a marked reduction in staining for all three antigens in proximal tubules from rats with active Heymann nephritis. Furthermore endocytotic uptake of intravenously injected FITC-dextran was considerably lower in diseased animals than in normal rats. Gp330 and rat IgG were identified as components of the luminal debris that accumulated during the course of Heymann nephritis. These results show that perturbation of proximal tubule endocytosis occurs in Heymann nephritis together with a loss of three apical antigens that are normally localized on membrane domains associated with the apical endocytotic pathway in these cells. The results also suggest that antibody-antigen complexes may be shed from the plasma membrane in both the glomerulus and the proximal tubule in this disease.

Colchicine-induced redistribution of an apical membrane glycoprotein (gp330) in proximal tubules.

Factors governing the selective, polarized insertion of membrane proteins are poorly understood, but some studies have suggested that microtubules are involved in the generation and maintenance of cell polarity. We have examined by immunocytochemistry the effect of the microtubule-disrupting agent, colchicine, on the cellular distribution of an endogenous glycoprotein, gp330, which is normally inserted only into the apical plasma membrane of proximal tubule epithelial cells. In control rats, gp330 was localized in the brush border and in apical invaginations and vesicles. Six hours after injection of colchicine, however, vesicles containing gp330 were dispersed throughout the entire cytoplasm of the cell. Many vesicles were packed into basolateral infoldings, close to the plasma membrane, but there was no significant insertion of gp330 into the basolateral membrane. When rabbit anti-gp330 antiserum was injected intravenously into colchicine-treated rats, immune complexes appeared in the glomerular basement membrane but could not be detected in peritubular basement membranes. This supports the conclusion that colchicine treatment does not result in the insertion of gp330 into the basolateral plasma membrane of proximal tubule cells. Our results indicate that although microtubules are involved in the accumulation of gp330-containing vesicles at the apical pole of the cell, other factors must be required for fusion with the plasma membrane to occur.

Effects of ischaemia on enzyme-activities in the soleus muscle of the rat.

1. The changes with the time of the activities of some energy-supplying enzymes and of the hydrolytic enzyme, acid phosphatase, were studied over 2 weeks of complete ischaemia, produced in the rat soleus muscle by section of the abdominal aorta and terminal devascularization, leaving nerve and tendon intact. 2. Activities of glycolytic enzymes, oxidative enzymes, hexokinase and acid phosphatase are affected in a different manner. Activities of the glycolytic enzymes, lactate dehydrogenase, triosephosphate dehydrogenase and glycerolphosphate dehydrogenase, are lowest on the 1st day and increase thereafter. The first two reach the control values again on the 4th and 14th day, respectively, while glycerolphosphate dehydrogenase reaches about 50% of the control value on the 14th day. The maximum decrease in activity of the oxidative enzymes, citrate synthase, beta-hydroxyacyl-CoA-dehydrogenase and malate dehydrogenase occurs later (4th day); thereafter their activity returns slowly to control values, but does not reach them even on the 14th day. Hexokinase activity is slightly decreased on the 1st day; then it increased and reached on the 7th day twice the control value. Thus on the 1st day the activity of the enzymes of aerobic metabolism prevail, and on the 4th day those of anaerobic carbohydrate (glucose) metabolism; the recovery of enzyme activity of aerobic oxidation occurs later. 3. Acid phosphatase activity increased from the 2nd day onwards, reaching up to 3 times the control value on the 4th day and still twice that value on the 14th day. This agrees well with the histochemical picture of acid phosphatase. 4. Histochemical changes of alkaline phosphatase activity reveal destruction of capillary endothelial cells during the first few days after operation and their later proliferation from the periphery, correlating with the loss and recovery of oxidative enzyme activity.

Effect of ischemia on contractile and histochemical properties of the rat soleus muscle.

Ligature and section of the abdominal aorta results in only minor and temporary functional and metabolic changes in the slow soleus muscle of the rat. A very small decrease in maximal tetanic tension corresponds to a few scattered areas of damaged and necrotic muscle fibres, in which decreased succinic dehydrogenase and loss of phosphorylase activity was observed. A new experimental approach, i.e. ligature and section of the abdominal aorta combined with terminal devascularisation, preserving intact tendons and innervation of the muscle causes maximal muscle ischemia, followed by an almost complete loss of tetanic tension output, marked shortening of contraction time and profound morphological and histochemical changes. The decrease in succinic dehydrogenase and ATPase activities and loss of phosphorylase activity occur in the majority of degenerating muscle fibres except for a thin rim of peripheral fibres during the first 4 days. Subsequently, the contractile properties recover gradually and enzyme activities reappear in the regenerating muscle fibres simultaneously with new revascularisation. Thirty days after the operation all the parameters observed returned to control values.

Effect of castration and testosterone administration on the neuromuscular junction in the levator ani muscle of the rat.

The ultrastructure of the neuromuscular junction (n.m.j.) of the androgen-sensitive levator ani muscle was studied in normal adult male rats, in 8-month-old rats castrated at the age of one month and in castrated rats treated with testosterone propionate (TP). Castration does not result in significant changes of the n.m.j. The density of synaptic vesicles and the postsynaptic junctional folds remain practically normal inspite of marked atrophy of the muscle. TP administration for 7 days results in marked changes in pre- and postsynaptic structures. There is slow progressive depletion of synaptic vesicles, appearance of cisternae and coated vesicles in axon terminals, and coalescence of coated vesicles with the plasma membrane. Coated vesicles are also found inside Schwann cells and among junctional folds. Dense core vesicles appear both in the axon terminals and in the postsynaptic area. Collateral sprouting of terminal axons with the formation of new immature junctions is observed. After 35 days of TP administration depletion of synaptic vesicles continues. Glycogen beta-particles, mostly freely dispersed, occasionally seen in axon terminals 7 days after TP administration, subsequently increase in number. In the endplate zone of the muscle fibre increased protein synthesis is indicated by a rapid increase in ribosomes and irregularly located myofilaments and myofibrils. The appearance of n.m.j. after testosterone administration resembles that described after nerve stimulation; the degree of change is however less pronounced.

Transfer to chick embryos of incompatible DNA.

After the transfer of chicken DNA to chick embryos incompatible at the B locus a retardation of growth was observed. Retarded differentiation of muscle fibres was histochemically detected in hatched chicks by the demonstration of enzymatic activities. The manifestations of apparent weakness of the dorsal muscles resembled a "myasthenia-like" syndrome. Infection with Marek's disease virus was not responsible for the damage caused by transferred DNA.

Immunological enhancement of muscle allografts induced by serum from tolerant rats.

Serum from tolerant animals induced immunological enhancement of muscle allografts. Serum from both animals bearing tolerated skin allografts and animals in which tolerance to skin grafts disappeared was effective. No significant differences between these two types of allografts were found with respect to contractile and histochemical behaviour. Serum from animals in which skin allografts survived transiently following non-specific treatment induced weak immunological enhancement. The changes in contractile and histochemical properties of muscle allografts serve as adequate parameters for assessment of the success of immunological enhancement.