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Biomedical subjects

J F Jones

Publications and source records attributed to J F Jones.

At least 37 records · Page 2Linked to original sources
PubMed1996

EBV infection of T cells: potential role in malignant transformation.

The presence of Epstein-Barr virus in different T-cell malignancies is now widely reported. In an effort to ascertain whether T cells are susceptible to EBV infection, we and others have detected the EBV receptor, CD21 on a population of immature thymocytes. We showed that EBV is a cofactor in stimulating proliferation of thymocytes. This proliferation may be a relevant factor in EBV-associated T-cell malignancies as well as EBV causation of acute infectious mononucleosis (AIM). We have further identified a subset of thymocytes that is infectable by EBV in which the genome remains linear in the first weeks after infection. We documented the transcription of the switch protein ZEBRA, an alternatively spliced form, RAZ, and EBNA-1 transcription from the Fp promoter. We hypothesise that EBV may be a cofactor in oncogenesis in T cells through several different pathways.

B-Lymphocytes↗
PubMed1996

MMPI profiles of patients with chronic fatigue syndrome.

Fifty-three patients with chronic fatigue syndrome (CFS) and 43 healthy nonpatient controls completed the Minnesota Multiphasic Personality Inventory (MMPI). All subjects varied in their degree of seropositivity to active Epstein-Barr virus (EBV) as measured by their anti-early antigen titers. EBV titers were higher among CFS patients and were associated with being more symptomatic. Differences in patient status were associated with statistically significant elevations on 8 of 9 clinical scales, 4 of which also showed clinically significant elevations (T scores > or = 70): scales 1, 2, 3, and 8. These results are discussed in terms of their implications for intervention strategies associated with MMPI-based CFS subtypes.

Adult↗
PubMed1996

Cloning and expression of the Epstein-Barr virus-encoded dUTPase: patients with acute, reactivated or chronic virus infection develop antibodies against the enzyme.

The gene encoding the Epstein-Barr virus (EBV)-specific dUTPase was amplified from virus DNA by PCR. The active enzyme was expressed in Escherichia coli and in insect cells as a non-fusion protein. The protein from E. coli specifically converted dUTP to dUMP and did not react with other dNTPs or NTPs. Preliminary experiments yielded a Km value of about 0.8 microM for dUTP. MAbs against the dUTPase reacted with a protein of approximately 31 kDa in 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-stimulated B cells harbouring either type 1 or type 2 EBV. The protein was found in untreated cells at low levels, whereas induction of the lytic replication cycle by TPA treatment or by providing the immediate early transactivator BZLF1 in trans resulted in increased expression. We demonstrated that the virus dUTPase isolated from EBV-infected cells is a phosphoprotein. The protein expressed in insect cells was used to test for the presence of specific antibodies in sera from normal, healthy carriers and from patients with various diseases. While the sera of EBV-negative individuals (0/3) or healthy carriers (0/33) did not contain detectable levels of antibodies, patients with mononucleosis (5/18), chronic EBV infection (2/7), EBV reactivation (7/20) and human immunodeficiency virus infection (5/24) showed elevated antibody titres against the enzyme. This indicated that the dUTPase is expressed during EBV replication and reactivation. The enzyme might therefore be a potential target for drug therapy under conditions of active DNA replication.

Acute Disease↗
PubMed1995

Heart rate responses to selective stimulation of cardiac vagal C fibres in anaesthetized cats, rats and rabbits.

1. The contribution of cardiac vagal C fibres to vagal chronotropic control in anaesthetized cats, rats and rabbits was analysed using electrical stimulation of the vagus nerve with a selective anodal block technique. 2. After bilateral vagotomy and pretreatment with atenolol, 10 Hz continuous selective stimulation of unmyelinated fibres in the cut peripheral end of the cervical vagus evoked a bradycardia in anaesthetized rats, cats and rabbits. With this stimulation protocol the three species exhibited a similar lengthening of the heart period (R-R interval) when expressed as a percentage of their basal cardiac interval. 3. The mechanism of action of the selective blocking technique was analysed by recording eighty-nine single A- (n = 12), B- (n = 22) and C-fibre (n = 55) vagal-projecting neurones in the medulla of the rat. This demonstrated that the technique can selectively block conduction in myelinated fibres and that 'break excitation' is seen mainly in unmyelinated fibres. Although thirty C fibres showed break excitation sixteen did not and this difference could not be correlated with their axonal conduction velocity, chronaxie or initial segment frequency following. 4. Using the anodal block technique the vagal effects on heart rate were reanalysed in the cat by incorporating a collision technique. B fibres were activated orthodromically to evoke cardioinhibition and simultaneously antidromically to collide with errant B-fibre spikes activated at the electrode producing anodal block. With this protocol it was noted that the B- and C-fibre bradycardias were not additive. Using a double anodal block and collision technique, it was demonstrated that this phenomenon was likely to be due to occlusion of the effects of B and C fibres. 5. In conclusion, in addition to the well-defined effects of vagal B fibres on heart rate, selective stimulation of vagal C fibres also had a cardioinhibitory effect in all three species studied. However, since the effects of cardiac C fibres on heart rate was small, these neurones alone cannot account for the cardioinhibition of the pulmonary chemoreflex. It is likely that activation of both B- and C-fibre cardiac vagal preganglionic neurones accounts for this reflex cardioinhibition.

Animals↗
PubMed1995

Epstein-Barr virus replicative gene transcription during de novo infection of human thymocytes: simultaneous early expression of BZLF-1 and its repressor RAZ.

Epstein-Barr virus (EBV) is known to infect B cells and epithelial cells. We and others have shown that EBV can also infect a subset of thymocytes. Infection of thymocytes was accompanied by the appearance of linear EBV genome within 8 hr of infection. Circularization of the EBV genome was not detected. This is in contrast to the infection in B cells where the genome can circularize within 24 hr of infection. The appearance of the BamHI ZLF-1 gene product, ZEBRA, by RT-PCR, was observed within 8 hr of infection. The appearance of a novel fusion transcript (RAZ), which comprised regions of the BZLF-1 locus and the adjacent BRLF-1 locus, was detected by RT-PCR. ZEBRA protein was also identified in infected thymocytes by immunoprecipitation. In addition, we demonstrated that the EBNA-1 gene in infected thymocytes was transcribed from the Fp promoter, rather than from the Cp/Wp promoter which is used in latently infected B cells. Transcripts encoding gp350/220, the major coat protein of EBV, were identified, but we did not find any evidence of transcription from the LMP-2A or EBER-1 loci in infected thymocytes. These observations suggest that de novo EBV infection of thymocytes differs from infection of B cells. The main difference is that with thymocytes, no evidence could be found that the virus ever circularizes. Rather, EBV remains in a linear configuration from which replicative genes are transcribed.

Antigens, Viral↗
PubMed1995

Activation of human thymocytes after infection by EBV.

The discovery of EBV in certain T cell malignancies and the expression of the EBV receptor, CR2/CD21, on a population of immature thymocytes, T lymphoblastoid cell lines, and childhood acute T lymphoblastic leukemia cells suggested that EBV-receptor interactions on T cells may be of importance. We have shown that, within the thymus, a population of large, immature cells expresses CD21. EBV altered the activation responses of immature thymocytes in vitro. Triggering through CD2 is mitogenic for mature, but not immature, T cells. However, during infection by EBV, ligation of CD2 caused thymocytes to proliferate in the absence of exogenous cytokines. This function was a result of the interaction of EBV with its receptor, CD21, but was caused by infection rather than surface signaling, because neither specific mAb nor the P3HR-1 strain of virus mimicked the effect of B95-8. Immature thymocytes were infected by EBV, as determined by the internalization of the viral genome and its transcriptional activity. Consistent with the activity of B95-8, EBNA-2 transcripts were identified within infected thymocyte populations. In addition, components of the viral replicative pathway were expressed during infection of thymocytes. These components included transcription of BZLF-1, an early gene that characterizes EBV-infected B cells after disruption of latency. A second transcript was identified as encoding the recently characterized RAZ, which also is associated with replicative infection. The consequences of EBV infection of T cells at an early stage of differentiation may lead to failure of normal T cell repertoire development, autoimmunity, or malignancy.

Antigens, Viral↗
PubMed1995

Model of Epstein-Barr virus infection of human thymocytes: expression of viral genome and impact on cellular receptor expression in the T-lymphoblastic cell line, HPB-ALL.

Infection of B lymphocytes and epithelial tissue by Epstein-Barr virus (EBV) is associated with malignancy and autoimmunity. The cellular receptor for EBV has been identified as CD21 (CR2). A molecule, which is biochemically and immunologically similar to B-cell CD21, has been identified on a subpopulation of immature thymocytes, suggesting a role for this molecule in the regulation of T-cell development and further suggesting that immature T cells might be susceptible to EBV infection. A growing body of literature now documents the presence of EBV in tumors of T-cell origin. We have evaluated the susceptibility of the human immature T cell line, HPB-ALL, to infection by EBV. Electron microscopy studies showed a rapid internalization of virus by HPB cells. Southern blotting showed the intracellular presence of linear EBV genomes, and components of the virus replicative cycle were identified. Expression of the BamHI Z region of the genome, encoding the nuclear protein, ZEBRA, which is strictly associated with productive infection in B cells, was detected in HPB-ALL cells. A spliced variant of Z, RAZ, was also identified. Cell surface expression of EBV late antigens was observed to occur transiently. Infection of HPB cells was also accompanied by altered expression of T-cell surface molecules involved in antigen recognition, a process critical to normal development of the T-cell repertoire. Delineation of the outcome of T-cell infection by EBV may lead to a better understanding of the role of this virus in autoimmune processes and malignancy.

Autoimmune Diseases↗
PubMed1995

Effects of 5-HT and 5-HT1A receptor agonists and antagonists on dorsal vagal preganglionic neurones in anaesthetized rats: an ionophoretic study.

1. Effects of ionophoretic administration of 5-hydroxytryptamine (5-HT) and selective 5-HT1A receptor agonists and antagonists on identified dorsal vagal preganglionic and dorsal raphe neurones were studied in pentobarbitone sodium or chloral hydrate-anaesthetized rats, respectively. 2. Extracellular recordings were made from 176 preganglionic neurones in the dorsal vagal nucleus (DVN). Application of 5-HT at low currents (< or = 10 nA) increased the activity of these neurones. However, at increased currents (10-60 nA), it had a predominantly depressant effect. Application of selective 5-HT1A receptor antagonists, (+/-)-pindolol or WAY-100635, attenuated the excitatory responses evoked by 5-HT. 3. Ionophoresis of the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (5-30 nA) increased the firing rate of 19 and decreased that of 67 of the 104 vagal neurones tested. Other 5-HT1A receptor agonists, flesinoxan and N,N-di-n-propyl-5-carboxamidotryptamine (DP-5-CT) also had predominantly depressant effects. 4. (+/-)-Pindolol attenuated excitations but not inhibitions evoked by 8-OH-DPAT. Surprisingly, WAY-100635 and 8-OH-DPAT produced the same effect on these neurones and when applied together, WAY-100635 failed to attenuate the 8-OH-DPAT responses. 5. Dorsal raphe neurones were identified by their low, regular firing rate and their subsequent histological localization. 8-OH-DPAT reversibly reduced the activity in all 7 neurones tested and this was antagonized by WAY-100635 in all 3 neurones tested. 6. In conclusion, 5-HT applied to vagal preganglionic neurones evokes excitatory and inhibitory responses. The excitatory, but not the inhibitory responses may be mediated, at least in part, by activation of 5-HT1A receptors.

Anesthesia↗
PubMed1995

Evidence that 5-HT1D receptors mediate inhibition of sympathetic ganglionic transmission in anaesthetized cats.

In anaesthetized cats, 5-carboxamidotryptamine (5-CT) or 5-hydroxytryptamine (5-HT) (0.3-300 micrograms kg-1,i.v.) inhibited the postganglionic compound action potential evoked by preganglionic electrical stimulation (0.5 Hz) with a similar potency in the stellate and splanchnic ganglia. In the 5-HT experiments transmission thorough the inferior mesenteric ganglia was also recorded. The maximal inhibitory effect of 5-HT was greater on the stellate and splanchnic ganglia (60 +/- 4 and 52 +/- 5%) than on the inferior mesenteric (15 +/- 2%). The effects of 5-HT were unaffected by pretreatment with antagonists (1 mg kg-1;i.v.) for 5-HT2 (BW501C67), 5-HT1A (WAY-100635) and 5-HT3 receptors (ondansetron). However, responses to both 5-HT and 5-CT were attenuated significantly by GR127935 (1 mg kg-1) except the responses to 5-HT at the inferior mesenteric ganglia. These results are consistent with the involvement of 5-HT1D receptors mediating inhibition of sympathetic ganglionic transmission in vivo.

Action Potentials↗
PubMed1994

The effects of oesophageal distension on diaphragm and laryngeal muscle activity in the anaesthetized cat.

The electromyographic (EMG) activities of diaphragm and laryngeal muscles were recorded during oesophageal distension in anesthetized cats. The responses to distension of the thoracic oesophagus differed from those evoked by distension of the cervical oesophagus. The crural component of the diaphragm (CD) was inhibited by distension of the thoracic oesophagus; distension of the cervical oesophagus did not affect CD EMG. Thyroarytenoid (TA) muscle EMG increased markedly and consistently in response to distension of the cervical oesophagus. Distension of the thoracic oesophagus only produced statistically significant increases in TA EMG with high distending volume (10 ml) at the level of the gastro-oesophageal junction. The main abductor of the vocal cords, the posterior cricoarytenoid (PCA) was either unchanged or decreased by oesophageal distension. The electrical activities of left paratendinous diaphragm, left costal diaphragm, internal intercostal and external intercostal muscles remained unchanged. The entire pattern would appear to constitute a means to aid passage of a bolus into the stomach, and simultaneously guard the respiratory tract from reflux or aspiration.

Anesthesia↗
PubMed1991

Chronic fatigue syndrome: I. Epstein-Barr virus immune response and molecular epidemiology.

Patients with chronic fatigue syndrome were compared to healthy seropositive control subjects in an open study and a case-control study analyzing spontaneous transformation rates of peripheral blood lymphocytes, EBV viral genome characteristics as determined by DNA restriction fragment polymorphisms, and antibody production by Western blot analysis. Thirty percent of patients versus 8% of control subjects underwent spontaneous transformation in the two studies. Viral genome patterns were overall similar to one another, with polymorphisms frequently present in BamHI B', K, H, and Y fragments. Only one line was found with the EBNA-2B genotype. Nineteen lines were found to contain viral DNA in the linear form suggesting active lytic replication. Western blot studies suggested that ill subjects made antibodies to lytic proteins more frequently than did healthy control subjects. Lack of control of EBV outgrowth in vitro is correlated with antibody evidence of active infection in vivo in some patients with chronic fatigue syndrome.

Antibodies, Viral↗
PubMed1991

Stress-related activation of Epstein-Barr virus.

Herpesviruses characteristically persist in a latent state in the body over the lifetime of an individual. Under certain conditions, any one of the herpesviruses can be reactivated. The mechanisms underlying the establishment of latent virus infection or viral reactivation are not well understood; however, it is known that the cellular immune response plays a very important role in the maintenance of latency and in virus reactivation. One of the factors thought to be associated with the reactivation of latent herpes-viruses is psychological stress. Using an examination stress model with medical student subjects, we previously demonstrated the reactivation of latent Epstein-Barr virus (EBV), as measured by increases in antibody titers. In this follow-up study using the same group of medical students, we found evidence for incomplete reactivation of latent EBV, with only selective expression of the latent virus genome.

Adult↗
PubMed1991

Severe combined immunodeficiency among the Navajo. I. Characterization of phenotypes, epidemiology, and population genetics.

Previous studies have identified a high incidence of severe combined immunodeficiency (SCID) among the Navajo Native American population. To determine the incidence and population genetics of this condition, we reviewed the death certificates of all children who died between 1969 and 1982, established the cases that met criteria identified in previously investigated cases, and interviewed the selected children's families. SCID cases were distributed spatially and temporally. Segregation parameter estimates of 0.27-0.38 were obtained from data from 24 interviewed families, suggesting an estimated gene frequency of 2.1% (arguing against a multifactorial inheritance). SCID cases referred to specialty centers lacked T and B cells in their blood, and their serum immunoglobulins ranged from absent to near normal.

Arizona↗
PubMed1990

The elderly on dialysis: some considerations in compliance.

Compliance with scheduled treatments, dietary and fluid restrictions, and multiple medications is an important component in the care and well-being of end-stage renal disease (ESRD) patients. Given the rigorus and complex demands of dialysis, it is important to examine the issue of compliance, focusing on a large and ever-increasing segment of our patient population, the elderly. The ESRD literature reflects efforts to define and measure levels of compliance, identify factors that influence and predict compliance, and develop intervention strategies to improve adherence to treatment regimens. While limited attention has been focused specifically on the elderly, there are studies suggesting that age may be a factor associated with improved adherence and that social support may be a significant contributor to compliance in this patient group. In an effort to examine the current status and needs of the dialysis elderly, research is in progress at Chromalloy American Kidney Center, Washington University, which replicates a study of 5 years ago. Eighty-four patients age 60 and over, on dialysis for a minimum of 6 months, were identified. Sociodemographic, treatment, compliance, and functional capacity data were collected; additional mental and psychological testing was completed on patients willing and able to participate. Preliminary data suggest the current elderly population is larger and significantly older than that of 5 years ago. Other sociodemographic data indicate the population is increasingly female, black, and more socioeconomically disadvantaged. In regard to compliance, the vast majority of elderly demonstrate good compliance as measured by serum potassium, fair to good compliance with phosphorus, and fair to poor compliance with fluid restrictions.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗