Suppression of sensitivity to change in target disparity during vergence eye movements

It has been demonstrated recently in human psychophysical experiments that sensitivity to surround displacement is suppressed during convergence eye movements. To determine whether sensitivity to changes in target disparity is also reduced, responses to test disparities that were superimposed on standard 4 degrees step disparities were investigated. The test disparities consisted of brief (20 ms) positive and negative pulses as well as steps (in the range of +/- 0.6 degrees). A two-alternative forced-choice procedure was used in which the test disparity was presented in either the first or the second portion of a trial. The results showed that suppression of both test pulse and step disparities began before the start of the convergence movement and continued during the movement. Maximum suppression was about 0.50 to 0.85 log units and occurred between 150 ms before to 50 ms after convergence onset. The differences in sensitivity curves for pulse and step stimuli suggest the presence of different central and peripheral neural factors during vergence eye movements.

[Toxic effects of moniliformin on heart function in rats]

The present study was carried out on intact heart of rat to determine the myocardial toxicity of moniliformin (MLFN) in vitro and in vivo Perfusion of MLFN 0.1 mumol/L in isolated heart decreased myocardial contractile force by 52 +/- 17%, and the effect was not reversible after the infusion of MLFN had stopped. The intravenous LD50 of MLFN in mice was found to be 17.51 +/- 1.64 mg/kg. Intravenous injection of MLFN at 1/4 LD50 markedly inhibited cardiac hemodynamic variables relative to myocardial contractile function. Particularly, it decreased left ventricular pressure development (dP/dt max) by 52 +/- 6%, and induced ventricular arrhythmia. The results showed that MLFN severely damaged the heart function of healthy rats.

[Effects of 2-[p-(dimethylamino)styryl] pyridine methiodide on conduction and refractory period of atrioventricular node in rat]

The effects of 2-[p-(dimethylamino)styryl] pyridine methiodide (DSPM) on rat ECG and HBE were studied. The P-R and R-R intervals of ECG were lengthened 40.3% and 115.4% respectively, after iv injection of DSPM 2 mg/kg. DSPM (1.5 and 2 mg/kg) affected the A-H interval in a dose-dependent manner with no change in the H-V interval of HBE. DSPM 0.5 mumol/L lengthened the A-H interval of isolated perfused hearts in frequency-dependent manner, with greater prolongation at higher frequency. The effect of verapamil on the A-H interval was less than that of DSPM. Propranolol had no effect on the frequency-dependent delay of atrioventricular node. DSPM 0.5 mumol/L lengthened the functional and effective refractory periods of atrioventricular node by 26.8% and 31% respectively. These phenomena support that DSPM may be a calcium antagonist.

Thymocytes stimulate metabolism of arachidonic acid in rat thymic epithelial cells

Arachidonic acid metabolites play an important role in the development of T cells in the thymus. In the normal animal, prostaglandin levels in the thymus are significantly higher than in plasma. Herein, we have studied the regulation of arachidonic acid metabolism using the thymic endocrine epithelial cell line, TEA3A1, and thymocytes. We have found that TEA3A1 cells, but not thymocytes, produced prostaglandins and thromboxanes. We have also found that thymocytes could stimulate the production of arachidonic acid metabolites in TEA3A1 cells when both cells were cocultured. The strongest stimulation was observed when TEA3A1 cells were cocultured with thymocyte subpopulations either negative for OX8 or W3/25 functional surface markers (either double-negative or single-positive thymocytes). Furthermore, cell-cell contact seems to be absolutely required for the activation of arachidonic acid metabolism in TEA3A1 cells. The study presented here describes the existence of a novel regulatory mechanism of arachidonic acid metabolism which may play an important role in the development of T cells in the thymus.

[An experimental study of basement membrane of the muscle grafts in the peripheral nerves]

The suitability of muscle basement membrane tubes as alternative to autogenous nerve grafting was appraised by comparing the nerve regeneration process in muscle basement membrane tube grafts used to bridge gaps in peripheral nerves with that in nerve grafts. The results revealed that nerve fibres grew through the muscle basement membrane tubes spanning a 2 cm gap and reinnervated end organ, at 20 weeks after operation, the nerve function recovered satisfactorily. However, the toe-spreading function, MCV and the amplitude of MAP on the muscle basement membrane tube grafting sides were not as good as on the nerve grafting sides, the axon diameter and degree of remyelination for the former also inferior to the latter. As time elapsed postoperatively, the difference between two kinds of grafts showed a tendency to diminish by all criteria used in this study. It imply that muscle basement membrane tube graft is a promising alternative to nerve grafting.

Chemosensory conditioning of Hermissenda crassicornis

Bite-strike responses of Hermissenda crassicornis, elicited by chemosensory stimulation of the lips, were found to be modified when food extracts were paired with rotation-produced stimulation of the statocysts. Animals that received repeated pairings of an extract of 1 food (conditioned stimulus, CS) with rotation exhibited suppressed bite-strike responses to that food for up to 48 hr after training. This suppression was usually specific to the trained food and was pairing-specific as well. Discriminative conditioning was also demonstrated. Animals trained with 1 CS paired with rotation and a second CS that was unpaired (CS-) showed suppressed bite-strike responses to the first CS. The results demonstrate that Hermissenda can learn to avoid foods that reliably signal an aversive event and may allow an analysis of higher order conditioning phenomena.

Phytochrome-regulated expression of genes encoding light-harvesting chlorophyll a/b-protein in two long hypocotyl mutants and wild type plants of Arabidopsis thaliana

The cab genes which encode the light-harvesting chlorophyll a/b-protein (LHCP) are expressed normally with respect to phytochrome regulation in the hy-3 and hy-5 long hypocotyl mutants of Arabidopsis thaliana. In etiolated seedlings of these mutants as well as of the wild type, 1 min of red light elevates cab mRNA levels substantially within 2 h; this increase is reversed if far-red light is given immediately after the red light treatment. We conclude that the genetic defects in these mutants do not affect steps in the signal transduction pathway leading to the regulated expression of cab genes. Additionally, the mRNA from one of the three known A. thaliana cab genes, AB140, is similar in quantity to the mRNAs from the other two, AB165 and AB180, in dark-grown seedlings of hy-3 and hy-5 as well as the parent A. thaliana (Landsberg) after a brief red light treatment. This aspect of cab gene expression differs from the strain Columbia of A. thaliana in which AB140 mRNA is the predominant message. In mature white light-grown plants of the strain Columbia, AB140 as well as a combination of AB165 and AB180 mRNAs are expressed at high levels, suggesting that AB165 and/or AB180 may be developmentally regulated.

Study of mechanisms of electric field-induced DNA transfection. I. DNA entry by surface binding and diffusion through membrane pores

A study of mechanisms of electrotransfection using Escherichia coli (JM 105) and the plasmid DNA pBR322 as model system is reported. pBR322 DNA carries an ampicillin resistance gene: E. coli transformants are conveniently assayed by counting colonies in a selection medium containing 50 micrograms/ml ampicillin and 25 micrograms/ml streptomycin. Samples not exposed to the electric field showed no transfection. In the absence of added cations, the plasmid DNA remains in solution and the efficiency of the transfection was 2 x 10(6)/micrograms DNA for cells treated with a 8-kV/cm, 1-ms electric pulse (square wave). DNA binding to the cell membrane greatly enhanced the efficiency of the transfection and this binding was increased by milimolar concentrations of CaCl2, MgCl2, or NaCl (CaCl2 greater than MgCl2 greater than NaCl). For example, in the presence of 2.5 mM CaCl2, 55% of the DNA added bound to E. coli and the transfection efficiency was elevated by two orders of magnitude (2 x 10(8)/micrograms DNA). These ions did not cause cell aggregation. With a low ratio of DNA to cells (less than 1 copy/cell), transfection efficiency correlated with the amount of DNA bound to the cell surface irrespective of salts. When the DNA binding ratio approached zero, the transfection efficiency was reduced by two to three orders, indicating that DNA entry by diffusion through the bulk solution was less than 1%. Square pulses of up to 12 kV/cm and 1 ms were used in the electrotransfection experiments. When cell concentration was 1 x 1010 cell/ml and DNA was added before the pulse, a transfection efficiency of up to 5 x 108/ microg DNA was obtained under optimum conditions (a single pulse of 8 kV/cm, 1 ms, in the presence of 5 mM CaCl2). When DNA was added to E. coli after the electric pulse, the efficiency of the transfection was dramatically reduced owing to the resealing of pores. Transfection was reduced to zero when DNA was added 2 h after the electroporation. However, transfection as high as 5 x 104/microg DNA was still recorded when DNA was added 10 min after the electric field was turned off. Because DNA entry took place in the absence of an electric field it could not be driven by the electrophoretic forces. DNA entry was facilitated by surface binding followed by lateral diffusion of the bound DNA into the cells through the field-induced membrane pores.

Pharmacokinetics of a mouse/human chimeric monoclonal antibody (C-17-1A) in metastatic adenocarcinoma patients

The pharmacokinetic characteristics of a mouse/human chimeric monoclonal antibody (C-17-1A) were determined in 10 patients with metastatic adenocarcinoma following the administration of either 10-mg or 40-mg infusions as a single or multiple dose. The administration of single 10-mg (n = 5) and 40-mg (n = 5) doses infused over 1 hr resulted in mean apparent steady-state distribution volumes of 4.13 +/- 0.97 and 5.16 +/- 1.92 liters, respectively, indicating that C-17-1A appears to distribute throughout the vascular compartment and into limited extracellular fluid volume. The disposition of C-17-1A was adequately characterized using a two-compartment open model with mean distribution half-lives of 15.8 and 18.5 hr and mean elimination half-lives of 90.0 and 97.6 hr for the 10- and 40-mg groups, respectively. A linear relationship was observed between AUC and dose (micrograms/kg). The clearance of C-17-1A was correlated linearly with total Ig, IgG, and tumor size. Multiple administration of either 10-mg (n = 3) or 40-mg (n = 3) doses of C-17-1A infused over 1 hr every 14 days for a total of three doses resulted in superimposable mean serum concentration versus time data and consistent mean pharmacokinetic characteristics. These data indicate that C-17-1A exhibits linear, nonsaturable distribution and elimination characteristics in man over the dose range studied (i.e., 130 to 880 micrograms/kg). The multiple-dose pharmacokinetics of C-17-1A were predictable, indicating a lack of an antibody response to C-17-1A over a period of 42 days.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of radix Salviae Miltiorrhizae on visceral pain discharges in the posterior nucleus of the thalamus in cats]

Extracellular microelectrode method and stereotaxic technique of brain were used to investigate the effects of Radix Salviae Miltiorrhizae on the discharges of visceral pain in the posterior nucleus of thalamus(po)in cats. Experiments showed that Radix Salvia Miltiorrhizae inhibited the discharges of visceral pain in po, Radix Salviae Miltiorrhizae acts directly on the peripheral nerve trunk and cannot block its exciting conduction. This suggests that the analgesic effect of Radix Salviae Miltiorrhizae is exerted via central nervous system.

Chemosensory conditioning of Hermissenda crassicornis

Bite-strike responses of Hermissenda crassicornis, elicited by chemosensory stimulation of the lips, were found to be modified when food extracts were paired with rotation-produced stimulation of the statocysts. Animals that received repeated pairings of an extract of 1 food (conditioned stimulus, CS) with rotation exhibited suppressed bite-strike responses to that food for up to 48 hr after training. This suppression was usually specific to the trained food and was pairing-specific as well. Discriminative conditioning was also demonstrated. Animals trained with 1 CS paired with rotation and a second CS that was unpaired (CS-) showed suppressed bite-strike responses to the first CS. The results demonstrate that Hermissenda can learn to avoid foods that reliably signal an aversive event and may allow an analysis of higher order conditioning phenomena.

Molecular cytogenetic evidence to characterize breakpoint regions in Robertsonian translocations

Four individuals carrying different Robertsonian translocations (13q;14q, 14q;21q, 14q;15q, and 13q;21q) were studied to determine the breakpoints involved in the generation of these derivative chromosomes. Sequential high-resolution G-banding, in situ hybridization using alphoid and ribosomal DNA probes, and C-banding were performed. In addition, silver staining was also used for visualization of the NOR region. The results provide direct molecular cytogenetic evidence that Robertsonian translocations can take place in different regions in both the short arm and proximal long arm of acrocentric chromosomes. Three different types of breakpoints were identified: between the ribosomal or alphoid sequences, as deduced from the banding and in situ hybridization results, and breaks in two seemingly unrelated regions on the two different chromosomes. The use of conventional cytogenetic techniques together with molecular studies allowed more precise evaluation of the breakpoints involved in Robertsonian translocations than either approach alone might have done.

Cell-mediated immune responses to poliovirus II. Survey of delayed hypersensitivity and T-cell proliferative responses in inbred mouse strains

Some epidemiological reports suggest a human genetic predisposition for susceptibility to the development of paralytic poliomyelitis. In a previous study of cell-mediated immune responses by mice to poliovirus (PV), we showed differences in the responses by BALB/c and C57BL/6 (B6) mice. The present study is a further analysis of the delayed hypersensitivity (DTH) and T cell proliferative (Tprlf) responses to PV in 17 different inbred strains of mice, to determine if these responses were under major histocompatibility complex (MHC) or other genetic control. Both DTH and Tprlf to PV did not correlate with MHC for responses to any of the three PV serotypes. Further, we found a lack of concordance of DTH and Tprlf responses to a given PV serotype. The cell-mediated immune responses by any one mouse strain to one PV serotype is not predictive of that mouse strain's response to another PV serotype.

Forward masking effects on early auditory evoked potentials

In early auditory evoked potentials (EAEPs) evoked by click trains, every click had a masking effect on the responses to the clicks following it and the whole response evoked by the click train was the sum of the masked responses to every click in the train. Special attention was paid to the situation when the inter-stimulus interval (ISI) was less than 10 ms and the responses to the individual clicks might be merged to form a continuous wave. The experiments showed that the more the number of the clicks preceding a given click in the train, the stronger the effect on the response to this click until the number was big enough and the effect became saturated; the shorter the ISI when it was less than 10 ms, the stronger the effect; the higher the intensity of the masker, the stronger the effect.

Lipocortin-independent effect of dexamethasone on phospholipase activity in a thymic epithelial cell line

In the cloned rat thymic endocrine epithelial cell line TEA3A1, treatment with dexamethasone leads to decreased levels of prostaglandin E2, prostaglandin F2 alpha, and thromboxane B2. Dexamethasone treatment also leads to a decrease of both calcium-dependent and calcium-independent phospholipase A2 activity measured in a cell-free assay. Dexamethasone-treated cells also have increased levels of lipocortin-I, a putative modulator of phospholipase A2 activity. The property of calcium-dependent binding of lipocortin to the particulate fraction was used to prepare cytosolic and particulate subcellular fractions which contained phospholiphase A2 activity but no lipocortin-I. Dexamethasone decreased phospholipase A2 activity in both cytosolic and particulate fractions even in the absence of lipocortin, suggesting the presence of a lipocortin-independent mechanism.

Mouse/human chimeric monoclonal antibody in man: kinetics and immune response

A mouse/human chimeric monoclonal antibody (mAb) composed of the variable regions of murine 17-1A mAb and the constant regions of human IgG-1K immunoglobulin was administered to 10 patients with metastatic colon cancer. Four patients received single infusion of 10 mg (n = 2) or 40 mg (n = 2). Six patients received three infusion of 10 mg (n = 3) or 40 mg (n = 3) at 2-week intervals. The pharmacokinetics were similar at both dose levels and at the second and third infusions. The plasma disappearance curves were best fit by a two-compartment model having a mean alpha T1/2 of 17.5 hr (range 13-23 hr) and a mean beta T1/2 of 100.5 hr (range 65-139 hr). One patient who received three 40-mg doses of chimeric IgG-1K 17-1A mAb (day 0, 14, and 28) was the only patient to exhibit a detectable but modest antibody reactivity to chimera on days 63 and 84. The antibody reactivity was inhibited by murine 17-1A mAb, indicating that the antibody response was directed to the murine variable region of the chimera. The patients had no toxic or allergic reactions. This chimeric form of 17-1A mAb has an approximate 6-fold longer circulation time and appears to be substantially less immunogenic than its murine counterpart. These characteristics may provide an advantage in the clinical application of such chimeric molecules in therapeutic trials in humans.

Direct preparations from chorionic villi--relationship between villous morphology and mitotic index

It has been postulated that chorionic villi with abundant sprouts have a higher mitotic index and are therefore preferable for obtaining direct chromosome preparations from chorionic villus samples. This theory was tested by correlating villous morphology with mitotic index. Surprisingly, no statistically significant relationship was found. Choice of culture medium, however, was found to be important, with serum-free RPMI yielding a higher mitotic index than 40 per cent FCS in MEM. We conclude that villous morphology, as assessed in this study, is not a major factor in determining the success of direct chromosome preparations.

Kallikrein stimulates arachidonic acid release and production of prostaglandins from TEA3A1 endocrine thymic epithelial cells

Using TEA3A1 rat endocrine thymic epithelial cells, we demonstrated that kallikrein (EC 3.4.21.35) not only stimulated the release of arachidonic acid (AA) and its metabolites from TEA3A1 cells but also enhanced the intracellular synthesis of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) by approx. 2-fold. The stimulatory effect of kallikrein was dose- and time-dependent and could be blocked by aprotinin, a kallikrein inhibitor. It was found that the phospholipase A inhibitors ONO RS082 [2-(p-amylcinnamoyl)amino-4-chlorobenzoic acid], and mepacrine (6-chloro-9-[(4-dimethylamino)-1-methyl)]amino-2-methoxyacridine; quinacrine) also inhibited the kallikrein-stimulated release of AA and its metabolites. It is suggested that the kallikrein-induced stimulatory effect might be mediated through a phospholipase A2 pathway. The effect of bradykinin was studied and no significant stimulation was observed, even at a high dose (10 micrograms/ml). This suggested that the formation of kinin does not have a role in the kallikrein-induced stimulation of AA release from TEA3A1 cells. Furthermore, the effect of kallikrein was also totally abolished by adding pepstatin A, a known inhibitor of renin, pepsin and cathepsin D which does not inhibit kallikrein itself. This indicates that kallikrein did not act on the phospholipase-like enzyme directly. There is at least one more enzyme, a pepstatin A-inhibitable proteinase, that acts as a mediator for kallikrein-induced regulation of AA release.