Intracellular transport of class I MHC molecules in antigen processing mutant cell lines

Intracellular transport and stability of class I MHC glycoproteins depends on the assembly of H chain, beta 2-microglobulin, and peptide. The Ag processing mutant cell lines T2 and RMA-S have defects in peptide loading of class I, resulting in reduced cell surface expression of class I molecules. Expression of class I molecules in the murine cell line RMA-S can be induced at 26 degrees C, suggesting that they are transported to the cell surface, but are unstable. However, most human class I molecules in T2 are poorly expressed at the cell surface, even at 26 degrees C. To directly compare the transport of human and mouse alleles in RMA-S and T2, the human alleles HLA-A2, A3, and B27 were transfected into RMA-S along with human beta 2-microglobulin, and the mouse alleles H-2Kb and Db were transfected into T2. Surface expression of HLA-A3 and B27 in RMA-S remained less than 10% of wild-type levels at 26 degrees C. H-2Kb and Db in both cell lines, however, were expressed at 20 to 30% wild-type levels at 37 degrees C and could be induced to wild-type levels at 26 degrees C or with peptides. The selective expression of murine class I glycoproteins at the cell surface of T2 is not because of their greater stability when associated with human beta 2m, since H-2Kb and Db H chain/human beta 2m complexes dissociate more rapidly in vitro than HLA-A3 and B27 complexes. These results suggest that the difference in transport between human and mouse class I in T2 reflects a fundamental structural property of the class I glycoproteins.

[The effect of ventricular pacing on plasma atrial natriuretic factor levels and its clinical significance]

The effects of increasing pacing rate on cardiac hemodynamics and the release of atrial natriuretic factor (ANF), cGMP and cAMP were studied in 21 patients underwent ventricular pacing. ANF levels elevated insignificantly in patients without VA conduction, but elevated significantly in patients with VA conduction at pacing rate of 90,110 and 160 beat/min. The intracardiac pressure between these two groups of patients did not show significant difference. The conclusions are: (1) elevation of ANF levels at increasing pacing rate is mainly due to atrial distension rather than atrial pressure per se. (2) The elevation of ANF levels may reflect the changes of hemodynamics, the higher the ANF level, the more increase in intracardiac pressure. (3) marked elevation of ANF level may suggest presence of VA conduction in patients during ventricular pacing.

Intracellular transport of class I MHC molecules in antigen processing mutant cell lines

Intracellular transport and stability of class I MHC glycoproteins depends on the assembly of H chain, beta 2-microglobulin, and peptide. The Ag processing mutant cell lines T2 and RMA-S have defects in peptide loading of class I, resulting in reduced cell surface expression of class I molecules. Expression of class I molecules in the murine cell line RMA-S can be induced at 26 degrees C, suggesting that they are transported to the cell surface, but are unstable. However, most human class I molecules in T2 are poorly expressed at the cell surface, even at 26 degrees C. To directly compare the transport of human and mouse alleles in RMA-S and T2, the human alleles HLA-A2, A3, and B27 were transfected into RMA-S along with human beta 2-microglobulin, and the mouse alleles H-2Kb and Db were transfected into T2. Surface expression of HLA-A3 and B27 in RMA-S remained less than 10% of wild-type levels at 26 degrees C. H-2Kb and Db in both cell lines, however, were expressed at 20 to 30% wild-type levels at 37 degrees C and could be induced to wild-type levels at 26 degrees C or with peptides. The selective expression of murine class I glycoproteins at the cell surface of T2 is not because of their greater stability when associated with human beta 2m, since H-2Kb and Db H chain/human beta 2m complexes dissociate more rapidly in vitro than HLA-A3 and B27 complexes. These results suggest that the difference in transport between human and mouse class I in T2 reflects a fundamental structural property of the class I glycoproteins.

Altered cerebrovascular responsiveness to N-methyl-D-aspartate after asphyxia in piglets

We examined effects of prior asphyxia and reventilation on pial arteriolar responses to arterial hypercapnia, topical application of forskolin, and topical application of N-methyl-D-aspartate (NMDA) in newborn pigs. Piglets were anesthetized and ventilated with a respirator. Pial arteriolar diameter was determined using a closed cranial window and intravital microscopy. After baseline diameter was determined, the respirator was turned off for 10 min. Then the respirator was turned on, and the piglet was ventilated for 4 h. At 1, 2, and 4 h after asphyxia, arteriolar diameter was determined during control conditions and during arterial hypercapnia (inspiration of 10% CO2 in air; n = 4), topical application of 2.4 x 10(-8) M forskolin (n = 6), and topical application of 10(-5) M NMDA (n = 6). At 1 h after asphyxia, arterial hypercapnia dilated pial arterioles by 39 +/- 3%, topical forskolin dilated pial arterioles by 24 +/- 3%, and NMDA dilated pial arterioles by 10 +/- 1%. For arterial hypercapnia and forskolin application, arteriolar responses were not different from 1 h at 2 and 4 h postasphyxia. In contrast, for NMDA, arteriolar responses were greater at 2 h (23 +/- 6%) and 4 h (30 +/- 5%) than at 1 h. In time-control animals, NMDA dilated arterioles by 20 +/- 5% at 1 h, by 24 +/- 8% at 2 h, and by 21 +/- 4% at 4 h (n = 5). Indomethacin administration (5 mg/kg iv) before asphyxia resulted in a 23 +/- 3% arteriolar dilation in response to NMDA at 1 h (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal model estimation of additive and dominance variances in egg production traits of poultry

An animal model analysis was used to estimate simultaneously additive (sigma 2a) and dominance (sigma 2d) variances for egg production traits within three White Leghorn lines. The data consisted of information for three generations on egg number (EN) produced at 18 to 25 (EN1), 26 to 65 (EN2), and 18 to 65 wk of age (EN3); egg weight (EW) measured at 30 to 35 (EW1) and 40 to 45 wk (EW2); and egg specific gravity (ESG) measured at 30 to 35 (ESG1) and 40 to 45 wk (ESG2). A transformation was used for EN2 and EN3 because of a skewed distribution. In total, 813 sires, 2,575 dams, and 28,649 daughters were involved in the analyses. Three genetic models (sire-dam, additive, and dominance) were compared in estimating heritability (h2). The sire-dam model underestimated h2 because it ignored animal relationships. The h2 estimates from the additive model were approximately 9 to 52% higher for EN and 2 to 18% higher for EW and ESG than those from the dominance model. The differences between the h2 estimates from the additive and dominance models were increased for larger dominance variance sigma 2d. Ratios of sigma 2d to total variance were high for EN (10 to 20%) and low for EW and ESG (1 to 13%). Ratios of sigma 2d to total genetic variance for EN1, EN2, EN3, EW1, EW2, ESG1, and ESG2 were 18 to 36, 29 to 43, 29 to 56, 1 to 26, 3 to 8, 20 to 27, and 2 to 14%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Localized membrane depolarizations and localized calcium influx during electric field-guided neurite growth

Our study explores the mechanisms behind neurite galvanotropism. Using phase, differential interference contrast and ratiometric fluorescence microscopy, we reveal four responses of N1E-115 mouse neuroblastoma cells to 0.1-1.0 mV/microns uniform DC electric fields: cathode-directed neurite initiation and elongation, cathode-biased growth cone filopodial protrusions, transient cathode-localized calcium increases, and persistent cathode-localized membrane depolarizations. These newly demonstrated events are temporally and spatially correlated, suggesting that they are causally related. The calcium increases are prevented by calcium channel blockers and by the removal of extracellular calcium. We therefore propose that the observed field-induced membrane depolarizations activate voltage-dependent calcium channels, resulting in cathode-localized calcium influx. This, in turn, may initiate the observed cathode-biased growth cone filopodial protrusions, followed by the cathode-directed neurite elongation.

[Effects of longevity-antihypertensive-mixture on essential hypertension and left ventricular hypertrophy]

A study which enrolled 65 middle-aged and elderly essential hypertensive patients with Kidney-deficiency pattern was carried out to evaluate the effects of Longevity-Antihypertensive-Mixture (LAM). As LAM was composed of Kidney-tonifying herbs, all the subjects chosen fell into the pattern of Kidney-deficiency in TCM. The subjects were randomized into two groups: The LAM group had 34, and the control group taking Apocyhum Venetum L. Fluid (AVLF) 31. The duration of medication was 12 weeks. The main results were as follows: (1) At the end of week 4, the supine systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean blood pressure (MBP) in LAM group declined from 171 +/- 16 (mmHg, the same below), 101 +/- 6 and 127 +/- 7 to 153 +/- 12, 93 +/- 7 and 113 +/- 7 respectively. At the end of week 12, the supine SBP, DBP and MBP were 151 +/- 14, 93 +/- 6 and 112 +/- 8. There was significance of difference in the reduction of supine blood pressure compared with baseline (P less than 0.001). AVLF produced similar changes in the reduction of supine SBP, DBP and MBP. However, the magnitude of reduction in SBP and MBP was smaller than those with LAM (P less than 0.001). (2) There was no significance of difference in attaining goal blood pressure between LAM and AVLF groups (P greater than 0.05). At the end of week 4, 79.41% and 77.42% were achieved respectively; at 12, 79.41% and 80.65%. (3) LAM had stronger effect on relieving symptoms of essential hypertension and Kidney-deficiency than AVLF (P less than 0.05). (4) In LAM group the left ventricular mass index (VMI) decreased from 114.75 +/- 42.40 g/m2 to 100.39 +/- 36.08 g/m2 (P less than 0.001). The LVMI in AVLF group increased from 117.27 +/- 36.90 g/m2 to 117.68 +/- 38.37 g/m2 (P greater than 0.05). The results supported the therapeutic principle of TCM: Treating patients according to their pathophysiological patterns.

Cardiac tamponade in rheumatoid arthritis. Successful treatment with intrapericardial steroid administration

Cardiac tamponade complicated by classic rheumatoid arthritis was markedly alleviated by pericardiocentesis and intrapericardial administration of steroid. For the following 2 years, no recurrence of cardiac tamponade or constrictive pericarditis was observed. According to the literature, only one other patient with cardiac tamponade complicating rheumatoid arthritis (RA) had been successfully treated patient by intrapericardial steroid administration.

Chlorination of taurine by human neutrophils. Evidence for hypochlorous acid generation

The model hydrogen peroxide-myeloperoxidase-chloride system is capable of generating the powerful oxidant hypochlorous acid, which can be quantitated by trapping the generated species with the beta-amino acid, taurine. The resultant stable product, taurine chloramine, can be quantitated by its ability to oxidize the sulfhydryl compound, 5-thio-2-nitro-benzoic acid to the disulfide, 5,5'-dithiobis(2-nitroben-zoic acid) or to oxidize iodide to iodine. Using this system, purified myeloperoxidase in the presence of chloride and taurine converted stoichiometric quantities of hydrogen peroxide to taurine chloramine. Chloramine generation was absolutely dependent on hydrogen peroxide, myeloperoxidase, and chloride and could be inhibited by catalase, myeloperoxidase inhibitors, or chloride-free conditions. In the presence of taurine, intact human neutrophils stimulated with either phorbol myristate acetate or opsonized zymosan particles generated a stable species capable of oxidizing 5-thio-2-nitrobenzoic acid or iodide. Resting cells did not form this species. The oxidant formed by the stimulated neutrophils was identified as taurine chloramine by both ultraviolet spectrophotometry and electrophoresis. Taurine chloramine formation by the neutrophil was dependent on the taurine concentration, time, and cell number. Neutrophil-dependent chloramine generation was inhibited by catalase, the myeloperoxidase inhibitors, azide, cyanide, or aminotriazole and by chloride-free conditions, but not by superoxide dismutase or hydroxyl radical scavengers. Thus, it appears that stimulated human neutrophils can utilize the hydrogen peroxide-myeloperoxidase-chloride system to generate taurine chloramine. Based on the demonstrated ability of the myeloperoxidase system to generate free hypochlorous acid we conclude that neutrophils chlorinate taurine by producing this powerful oxidant. The biologic reactivity and cytotoxic potential of hypochlorous acid and its chloramine derivatives suggest that these oxidants play an important role in the inflammatory response and host defense.