Molecular characterization of novel reciprocal translocation t(6;14) in an Epstein-Barr virus-transformed B cell precursor

An in vitro culture of FLEB14 cells, an Epstein-Barr virus-transformed B cell precursor containing the germ line immunoglobulin genes, gave rise to a uniclonally expanded variant, FLEB14 delta 3, which was rearranged at the immunoglobulin heavy-chain gene locus. Cytogenetic analysis showed that FLEB14 delta 3 had a novel reciprocal translocation, t(6;14)(q15;q32). Molecular cloning of the rearranged DNA fragments and determination of their nucleotide sequence revealed that the recombination event was reciprocal, imprecise, and nonhomologous and took place in the S mu region, like those found in Burkitt's lymphoma cells. We propose a molecular model to explain this genetic event which may be relevant to class switch recombination. The translocated sequence of chromosome 6 did not contain any known oncogenes, although the sequence is conserved among mammals. FLEB14 delta 3 did not show tumorigenicity.

Effects of angiotensin I converting enzyme (ACE)-related substances on prostacyclin generation and ACE activity of human vascular endothelial cells and rat aortic rings

The effects of angiotensin I (ANG I) converting enzyme (ACE)-related substances on prostacyclin (PGI2) generation were investigated using cultured human vascular endothelial cells (EC) and rat aortic rings. ANG I or bradykinin (BK) increased while captopril decreased PGI2 generation and ACE activity of EC, whereas ANG II was without effect. The enhancement of PGI2 generation induced by ANG I or BK was not affected by the pretreatment with captopril. In rat aortic rings, ANG I, ANG II, and BK enhanced whereas captopril (10(-3) M) attenuated PGI2 generation. Mechanical stimulation of aortic rings stimulated PGI2 generation. These results suggest that (a) the conversion of ANG I to ANG II did not enhance PGI2 generation in EC; (b) the ANG II stimulated PGI2 generation of aortic rings was partially derived by mechanical stimulation of EC, probably originating from the contraction of smooth muscle cells by ANG II; (c) captopril directly inhibited PGI2 generation; and (d) in EC, the stimulation of PGI2 generation by ANG I or BK is probably regulated by an activating effect on ACE as an autoregulatory mechanism.

Effects of angiotensin I converting enzyme (ACE) related substances upon the vascular prostacyclin generation

We investigated the interaction of angiotensin I (AI) converting enzyme (ACE) related substances to prostacyclin (PGI2) generation and ACE activity using cultured human vascular endothelial cells (EC) and rat aortic rings (AR). In case of cultured EC, AI and bradykinin (BK) increased PGI2 generation and at the same time ACE released from EC, however angiotensin II (AII) did not show any effect on both of them. When the EC were pretreated by captopril both of basal PGI2 production and ACE activity were reduced but the enhancing effects on PGI2 generation by AI or BK were preserved. On the other hand in the experimental system with AR, not only AI or BK but also AII increased PGI2 generation and the higher concentration of captopril inhibited PGI2 generation. When the EC were removed, the enhancing effect by AII was diminished and the mechanical stimulation to AR remarkably increased PGI2. From these experimental studies, we obtained the results that (1) the reported hypothesis that the vasodilative effect of captopril would be developed by the enhanced PGI2 generation was not confirmed in our systems of EC and AR. (2) AII did not affect on PGI2 generation of EC. Therefore the enhanced PGI2 generation by AII in AR was considered to be mainly derived from the mechanical stimulation to EC by the AII induced smooth muscle cells contraction. (3) It was speculated that the enhanced PGI2 generation by AI or BK might be modulated through their activating effect on ACE as an autoregulatory mechanism.

An Epstein-Barr virus (EBV)-determined nuclear antigen (EBNA5) partly encoded by the transformation-associated Bam WYH region of EBV DNA: preferential expression in lymphoblastoid cell lines

Four peptides were synthesized on the basis of amino acid sequences deduced from a highly spliced transcript encoded by the Bam W, Y, and H fragments of the Epstein-Barr virus (EBV) genome [Bodescot, M., Chambraud, J. B., Farrell, P. J. & Perricaudet, M. (1984) EMBO J. 3, 1913-1917]. Rabbit antisera against three of the four peptides identified a nuclear polypeptide that varied between 22 and 70 kDa in molecular size. Four of 20 EBV-positive human sera contained antibodies against this polypeptide. Since this is the fifth EBV-determined nuclear antigen (EBNA) discovered in growth-transformed cells, it is designated EBNA5. The antigen was detected in virus nonproducer lines (less than 0.01% EBV early antigen expression) and is thus not dependent on the viral cycle. It was differentially expressed depending on the origin of the lines. All 10 lymphoblastoid cell lines tested expressed EBNA5, but it could not be detected in 10 of 11 EBV-carrying Burkitt lymphoma lines. Infection of tonsillar lymphocytes with the B95-8 strain of EBV induced six EBNA5-specific polypeptides that varied between 41 and 70 kDa in molecular size with regular increments of 6 kDa. This may be due to the fact that the EBNA5 coding sequence includes the Bam W internal repeat. Parallel infection of the EBV-negative Burkitt lymphoma line Ramos with the same viral substrain did not induce detectable levels of EBNA5, nor was this antigen present in permanently EBV-converted Ramos sublines. These findings imply that the expression of the viral genome varies among B cells having different phenotypes.

Augmentation of synaptic responses in the dentate gyrus by daily electrical stimulation of the amygdala in cats

When the amygdaloid complex was electrically stimulated, polysynaptic evoked potentials were produced in the ipsilateral dentate gyrus of the hippocampal formation. Twenty-four hours after tetanic stimulation of the amygdala, the dentate response to single test pulses was found to be increased in amplitude. Stimulation trains presented at a rate of 1/day had a cumulative effect on the dentate evoked potential, which attained 5-10 times the original response in amplitude. The results imply that the efficiency of synaptic transmission in the amygdalo-hippocampal pathway can be modified, associated with amygdaloid kindling.

Biphasic modulation of spontaneous activities of entopeduncular neurons by systemic application of apomorphine in anesthetized cats

The responses of entopeduncular neurons to apomorphine were investigated with extracellular recording methods in anesthetized cats. Apomorphine was applied intravenously in increasing doses, which cumulatively doubled with each addition (5-640 micrograms/kg). The spontaneous firing rates of entopeduncular neurons, which were inhibited by electrical stimulation of the caudate nucleus, increased when lower doses of apomorphine (5-20 micrograms/kg) were applied. However, higher doses (40-640 micrograms/kg) produced a dose-dependent decrease in the firing rate. The results suggest that there are direct and indirect effects of systemically administered apomorphine on entopeduncular neurons which may contribute to biphasic responses in the spontaneous discharge rate.

Liquid chromatographic determination of tetracycline residues in meat and fish

A simple and rapid method was developed for quantitative determination of common tetracyclines, such as oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC), in meat and fish. Tetracyclines were extracted with aqueous HCl, and then centrifuged. The supernate was applied to an Amberlite XAD-2 column, which was washed with water and eluted with methanol. The eluate was concentrated to about 0.5 mL under vacuum at 35 degrees C, and then measured by liquid chromatography and UV detection. Two analytical columns were used for confirmation. The average recoveries of OTC, TC, and CTC from meat and fish fortified at 1, 1, and 3 ppm were 82.6, 81.5, and 67.0% respectively.

Orthodromic and antidromic responses of nucleus accumbens neurons to stimulation of amygdala and substantia nigra in cats

Response of nucleus accumbens neurons to stimulation of the amygdala and the substantia nigra were investigated extracellularly in anesthetized cats. They were excited by stimulation of the basolateral amygdaloid nucleus with latencies of 9.0-20.0 ms (mean 12.8 ms). About 70% of them were activated antidromically with latencies of 5.5-33.0 ms (mean 18.8 ms) following stimulation of the substantia nigra pars reticulata. The nucleus accumbens thus relays signals from the amygdaloid complex to the substantia nigra, and may act to bridge the limbic system to the basal ganglia.

[Development of clear zone after total hip replacement (author's transl)]

For studying the durability of Charnley-Müller's total hip prosthesis, 141 joints of the cases which had past at least 5 years from the operation were followed up by means of X-ray pictures to reveal the processes of CZ (clear zone at the interface between bone and cement) progress and loosening generation. Results 1) CZ which occurred once never disappeared and progressed in many cases. 2) The progress of CZ was supposed to be related to age and disease, but no relation was recognized with biomechanical factors. 3) The incidence of CZ was 83.7% on the acetabular side and 49.6% on the femoral side. 4) CZ of Stage I and II occurred within 1 year after the operation in many cases and CZ of Stage III and IV tended to increase about 3 years and 4 years after the operation, respectively, in the acetabular side, while in the femoral side Stage I occurred within 1 year in many cases, Stage II and III increased about 3 years after and Stage IV did about 4 years after. 5) The term for progressing from a stage to the next one considerably varied till Stage III, including non-progressive cases, but the term from Stage III to Stage IV was within 3 years in all the cases. 6) The durability of Charnley-Müller's total hip prosthesis observed in X-ray pictures was as low as 63.1%, 89 out of 141 joints 5 years after the operation, and it would be lower for a long time. The durability was particularly low in young cases of osteoarthritis. 7) The X-ray findings of loosening preceded clinical findings; thus precise interpretation of X-ray findings is useful for decision of prognosis and therapy.

The mole of pallido-thalamic transmission investigated with intracellular recording from cat thalamus

Pallido-thalamic transmission was studied by intracellular recording from neurons in the ventrolateral (VL) and ventroanterior (VA) nuclei of the thalamus in cats anesthetized with pentobarbital. Stimulation of the entopeduncular nucleus (ENT) produced short latency, inhibitory postsynaptic potentials in the VL-VA neurons (1.60 ms on average). When stimuli were applied closer to the VL-VA region along the pallido-thalamic pathway, i.e., to the rostral Forel's field, the IPSP latency was significantly reduced. Linear regression analysis of the IPSP latency against conduction distance between different stimulating the recording positions indicated that the IPSP was produced through a monosynaptic pathway at a conduction velocity of 5 to 11 m/s. The neurons which received IPSPs from the ENT distributed in the rostromedial VL and in the rostral VA, whereas relay cells responding only to the contralateral brachium conjunctivum were found in the caudal VL and in the dorsolateral portion of the rostral VL-VA complex. Reciprocal convergence of pallidal and cerebellar impulses were observed in only a small number of cells, which were located in the border between the two neuron groups. Recording of extracellular field potentials and focal stimulation within and around the rostral VL also indicated that the fiber potentials arose from the ENT nucleus and propagated along a bundle of fibers which terminated within the rostromedial VL-VA complex. These results are all explicable by assuming that the entopeduncular neurons are inhibitory in nature and so inhibit thalamic neurons monosynaptically.

Monosynaptic inhibition of thalamic neurons produced by stimulation of the substantia nigra

Electric stimulation to the substantia nigra (Pars reticulata) produced a monosynaptic inhibition of the neurons of the ventromedial nucleus of the thalamus in anesthetized cats.