T-dependent destruction of thyroid isografts exposed to IFN-gamma

Several autoimmune diseases are accompanied by tissue-specific expression of class II molecules of the MHC, and it has been suggested that this elicits a T cell response against tissue-specific Ag to which the individual is not tolerant. However, recent transgenic studies have indicated that non-lymphoid expression of class II genes in the pancreas, liver, and kidney is either innocuous or induces peripheral tolerance. To test this hypothesis in another organ-specific autoimmune disease, we attempted to induce autoimmune thyroiditis in normal mice with class II+ thyroid tissue. Normal thyroid lobes were cultured with and without IFN-gamma and then transplanted to adult isogeneic recipients. The thyroid that had been induced to express class II genes by IFN-gamma was destroyed in normal mice, whereas the control cultured thyroid and the native cervical gland survived. Both types of transplants remained intact and functional in congenic nu/nu recipients, indicating that neither exposure to IFN-gamma nor expression of class II genes compromised the thyroid. Thus, in some tissues, exposure to IFN-gamma and/or the induction of class II expression can lead to T-dependent autoimmune disease.     

Regional distribution of blood flow within the diaphragm

We investigated the regional distribution of blood flow (Q) within the costal and crural portions of the diaphragm in a total of eight anesthetized supine mongrel dogs. Q was measured with 15-microns microspheres, radiolabeled with three different isotopes, injected into the left ventricle during spontaneous breathing (SB), inspiratory resistive loading (IR), and mechanical ventilation after paralysis (P). At necropsy, the costal and crural portions of each hemidiaphragm were arbitrarily subdivided along a sagittal plane into five to seven and three sections, respectively. During P, there was a dorsoventral Q gradient within the costal part of the diaphragm. During SB there was a fourfold increase in the gradient of Q. Furthermore, during IR, in which mouth pressures of -16 +/- 4 cmH2O were generated, there was a further increase in the gradient of Q. During both SB and IR, Q to the most ventral portion of the costal diaphragm was 26 +/- 6% less than the peak value. In two dogs, studied prone and supine, there was no difference in the Q gradients between the two postures. Over the dorsal 80% of the costal diaphragm there was also a dorsoventral gradient of muscle thickness, such that the most dorsal part was 54 +/- 2% (n = 5) that of the ventral portion. In contrast, there was no consistent gradient of Q or muscle thickness within the crural diaphragm. Our results demonstrate a topographical gravity-independent distribution of Q in the costal, but not the crural, diaphragm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Two forms of sensitization of the local bending reflex of the medicinal leech

Sensitization of the local bending reflex of the medicinal leech Hirudo medicinalis was studied in a semi-intact preparation in which behavioral and electrophysiological recordings were made simultaneously. 1. Sensitization of local bending could be produced in two ways: by repeated stimulation of the mechanoreceptor sensitive to pressure (the P cell), and by stimulation of the mechanoreceptor sensitive to noxious stimuli (the N cell). 2. Both forms of sensitization produced a central neuronal change, measured as an increase in the number of stimulus-evoked action potentials in cell 3 (an excitor of dorsal longitudinal muscles). 3. Intracellular stimulation of serotonin-containing neurons 21 and 61 mimicked the sensitizing stimuli, but stimulation of the Retzius cell, which also contains serotonin, did not. 4. Stimulation of the Leydig cell, which releases octopamine, decreased the strength of local bending.     

A One Year Audit of Fine Needle Aspiration Cytology For the Pre-Operative Diagnosis of Breast Disease

In 1988, 985 patients presenting with breast disease, most with a palpable abnormality, were investigated by the triple approach (clinical examination, imaging and fine needle aspiration cytology [FNAC]). Using FNAC, 28% of patients were diagnosed as having carcinoma, 45% benign disease, 4% had suspicious cytology and 3% equivocal cytology. The remaining 20% had inadequate aspirates. Two false positive diagnoses of carcinoma were made (a false positive rate of 0.7%); one was a case of high grade non-Hodgkin's lymphoma and the other a papillary lesion with epithelial atypia. The false negative rate was 6.4%. Of these 49 patients, six had carcinoma-in-situ and 19 had low grade tumours. The absolute and complete sensitivities for the diagnosis of carcinoma in this series were 84.7% and 91.9% respectively and the absolute and complete specificities 99.7% and 98.3%, respectively. These figures compare favourably with those from other centres and confirm the efficacy of FNAC as part of the triple approach to the diagnosis of breast disease. The use of FNAC has resulted in a reduction in the number of Trucut and frozen section biopsies performed. Eighty three per cent of the patients with benign disease diagnosed by the triple approach have avoided excision biopsy, none of whom have subsequently been found to have carcinoma. Eighty patients with advanced breast carcinoma were spared operative intervention.     

Carbonmonoxy dopamine beta-hydroxylase. Structural characterization by Fourier transform infrared, fluorescence, and x-ray absorption spectroscopy

The carbon monoxide complex of ascorbate-reduced dopamine beta-hydroxylase has been prepared and characterized by Fourier transform infrared, fluorescence, and x-ray absorption spectroscopies. CO has previously been shown to be a competitive inhibitor with respect to O2, and binds to only one of the two copper atoms/active site (Blackburn, N. J., Pettingill, T. M., Seagraves, K. S., and Shigeta, R. T. (1990) J. Biol. Chem. 265, 15383-15386). Thus, it acts as an excellent probe of the O2-binding site. A single C-O infrared absorption band is observed at 2089 cm-1, shifting by 46 cm-1 to lower energy on substitution with either 13C16O or 12C18O. The 13C isotope shift is reversed to the position expected for 12CO upon vacuum flushing with 12CO gas, indicating that formation of the CO adduct is a fully reversible process. Binding of the substrate tyramine does not eliminate the infrared peak but causes a 3-cm-1 shift to lower energy. On the other hand, binding of a bifunctional inhibitor which cross-links the substrate and O2-binding site does eliminate the CO peak. These data, in conjunction with the competitive nature of CO binding with respect to O2, identify the CO-binding site as the O2-binding site, and place it in close proximity to the substrate-binding site. CO-dopamine beta-hydroxylase exhibits no luminescence in the visible region, suggesting a structure different from carbonmonoxy hemocyanin, and in all probability mononuclear. Analysis of extended x-ray absorption spectroscopy data is most consistent with an average coordination per Cu of 2-3 histidines, 0.5 CO, and 0.5 S atoms as ligands, and absorption edge comparisons indicates pseudo-4 coordination as the most likely geometry at each Cu(I) center. The results can be interpreted by a model involving inequivalent 4-coordination at each Cu(I) center in the CO adduct with CuAHis3S...CuBHis2CO-X as the coordination most consistent with all of the data.     

Quality control in the determination of cortisol in plasma/serum by using, on every sample, two different three-step separation methods including ultrafiltration, restricted-access high-performance liquid chromatography and reversed-phase high-performance liquid chromatography, and contrasting results to immunoassays

Tests of HPLC columns with restricted access, polymer covered alumina, polymer, and different ODS phases showed that base-acid compatible ODS columns gave the best peak shapes of cortisol, internal standard, as well as of plasma/serum (P/S) matrix components. Further trials with cortisol in P/S showed that three separation steps were essential in order to obtain chromatographic data which were superior to immunoassay data. Also, sufficient confidence in results required determination of each sample with two newly developed separation methods: (a) pre-separation with a restricted access column, concentration of the desired cut with a 20 mm base-acid compatible ODS column, and analysis with a 250 mm column filled with the same ODS; (b) pre-separation with an ultrafilter followed by the last two steps in (a). For detection UV was preferred over fluorescence. This twin multistep chromatography showed that immunoassays were very treacherous in that they produced a spectrum of results ranging from good to untenable without any warning whatever about functionality. The measurement of official controls, with reference values derived via gas chromatography-isotope dilution mass spectrometry, also demonstrated the superiority of the double HPLC method.     

Effects of nitrogen limitation on water relations of jack pine (Pinus banksiana Lamb.) seedlings

The water relations of shoots of young jack pine (Pinus banksiana Lamb.) seedlings were examined 6 and 15 weeks after the initiation of four different dynamic nitrogen (N) treatments using a pressure-volume analysis. The N treatments produced a wide range of needle N concentrations from 12 to 32 mg g^?1 dry mass and a 10-fold difference in total dry mass at 15 weeks. Osmotic potential at full turgor did not change over the range of needle N concentrations observed. Osmotic potential at turgor-loss point, however, declined as N concentrations decreased, indicating an increased ability of N-deficient jack pine plants to maintain turgor. The increase could be attributed largely to an increase in cell wall elasticity, suggesting that elasticity changes may be a common, significant adaptation of plants to environmental stresses. Dry mass per unit saturated water almost doubled as needle N level dropped from 32 to 12 mg g^?1 and was inversely correlated to the bulk modulus of elasticity. This suggests that cell wall elasticity is determined more by the nature of its cross-linking matrix than by the total amount of cell wall material present. Developmental change was evident in the response of some water relation variables to N limitation.     

Ligninolytic enzyme activity: A comparison of the veratryl alcohol and Azure B assay systems

Summary Ligninolytic enzyme activities in cell-free culture filtrates of Coriolus versicolor, Fusarium solani and Phanaerochaete chrysosporium were assessed using a veratryl alcohol oxidation assay system and results compared with those obtained using a relatively new assay system based on the oxidation of Azure B.     

Spatial clumping of food increases its monopolization and defense by convict cichlids, Cichlasoma nigrofasciatum

The hypothesis that resource monopolization and defense increaseas the spatial clumping of resources increases was tested usinggroups of three convict cichlids competing for 120 Daphnia magnaprey. Spatial clumping was manipulated by varying the distance(3, 20, or 40 cm) between three tubes through which the preyappeared. As predicted, monopolization of prey (percentage eatenby the dominant fish) and frequency of aggression (chases perminute) by dominant fish increased significantly as the distancebetween the tubes decreased. However, there was no evidenceof individual flexibility in the aggressiveness (percentageof conspecifics chased) of dominant fish across treatments.Differences among dominant fish in aggressiveness were positivelycorrelated with their ability to monopolize prey, but the strengthof the correlation decreased as the distance between the tubesincreased. Aggression appears to be a more effective mechanismof interference competition when resources are clumped thanwhen resources are dispersed.