Quantitative and qualitative analyses of the immune responses induced by a multivalent minigene DNA vaccine

Vaccines containing minigenes - isolated antigenic epitopes encoded by short open reading frames - can, under certain circumstances, confer protective immunity upon the vaccinee. Here we evaluate the efficacy of the minigene vaccine approach using DNA immunization and find that, to be immunogenic, a minigene-encoded epitope requires a perfect "Kozak" translational initiation region. In addition, using intracellular cytokine staining, we show that immunization with a plasmid encoding a full-length protein induces epitope-specific CD8(+) T cells which are detectable directly ex vivo, and constitute approximately 2% of the vaccinee's splenic CD8(+) T cells. In contrast, such cells are undetectable directly ex vivo in recipients of a minigene vaccine. Nevertheless, the minigene plasmid does induce a low number of epitope-specific CD8(+) T cells, which can be amplified to detectable levels by in vivo stimulation. Indeed, 4 days after in vivo stimulation (by virus infection), all vaccinated mice - regardless of whether they had been vaccinated with the minigene or with the full-length gene - had similar numbers of epitope-specific CD8(+) T cells. However, despite these strong responses at 4 days post-infection, recipients of the minigene vaccine showed no enhanced ability to limit virus replication and dissemination. We therefore observe a dichotomy; minigene vaccinees are not protected, despite the presence of strong virus-specific immune responses at 4 days post-challenge. We suggest that the protective benefits of vaccination exert themselves very soon - perhaps within minutes or hours - after virus challenge. If the vaccine-induced immune response is too low to achieve this early protective effect, virus-specific T cells will expand rapidly, but ineffectually, leading to the strong but non-protective response measured at 4 days post-infection. Thus, vaccine-induced immunity should be monitored very early in infection, since the extent to which these responses may later be amplified is largely irrelevant to the protection observed.

Virus-induced diabetes in a transgenic model: role of cross-reacting viruses and quantitation of effector T cells needed to cause disease

Virus-specific cytotoxic T lymphocytes (CTL) at frequencies of >1/1, 000 are sufficient to cause insulin-dependent diabetes mellitus (IDDM) in transgenic mice whose pancreatic beta cells express as "self" antigen a protein from a virus later used to initiate infection. The inability to generate sufficient effector CTL for other cross-reacting viruses that fail to cause IDDM could be mapped to point mutations in the CTL epitope or its COO(-) flanking region. These data indicate that IDDM and likely other autoimmune diseases are caused by a quantifiable number of T cells, that neither standard epidemiologic markers nor molecular analysis with nucleic acid probes reliably distinguishes between viruses that do or do not cause diabetes, and that a single-amino-acid change flanking a CTL epitope can interfere with antigen presentation and development of autoimmune disease in vivo.

Adherence to antiviral drug regimens in HIV-infected adolescent patients engaged in care in a comprehensive adolescent and young adult clinic

Inconsistent use of antiviral medications for the treatment of HIV may lead to the emergence of resistant strains in HIV-infected adults. Patterns of adherence with these drug regimens in adolescents remains unknown. Identifying nonadherence in HIV-infected patients to antiviral regimens and developing corrective measures could improve patient outcomes. This study was undertaken to understand adherence in HIV-infected youths engaged in care and to reduce patterns of nonadherence. A retrospective analysis of 25 charts (78%) of HIV-infected youths (n = 32, age 13 to 21 years) were consecutively reviewed from January 1993 to May 1998. Charts were reviewed for documentation of factors previously documented to be associated with adherence: housing stability, social support, prior sexually transmitted diseases (STDs) and/or pregnancy, HIV exposure category, number of clinic visits, number of pills per day, number of medications per day, knowledge of medication schedule, age, gender, race/ethnicity, health status as revealed by CD4 count and viral load, and recorded patterns of adherence to medications and clinic appointments. Thirteen of the 18 (72%) patients who were receiving antiretroviral medication were nonadherent. Sixty-seven percent of the females and 80% of the males reported missing doses. Housing instability (p = 0.031) and/or length of treatment with antiviral medications (months of treatment) (p = 0.043) were significantly correlated with nonadherence. The stability of the adolescents' living situations was the most significant correlate of medication adherence for this population of HIV-infected youth.

Identification and molecular characterization of the new alpha-1-antitrypsin deficient allele PI Y barcelona (Asp256-->Val and Pro391-->His). Mutations in brief no. 174. Online

To characterize the molecular basis of the "new" alpha1-antitrypsin (alpha1AT) deficient variant, PI Y barcelona, DNA sequence analysis of the coding exons of the alpha1AT gene was carried out using an amplification DNA technique and direct sequencing. The PI Y barcelona allele differs from the normal M1(Val213) allele sequence by two point substitutions: a transversion of GAT TO GTT in exon III in the codon for residue 256, resulting in the amino acid change of Asp256 to Val256, and a transversion of CCC to CAC in exon V in the codon for residue 391, resulting in the amino acid substitution of Pro391 to His391. On isoelectric focusing analysis these substitutions result in a cathodal migration of the "new" variant close to the PI Z. The index case, diagnosed with severe obstructive pulmonary disease, initially phenotyped a PI ZZ, was homozygous for PI Y barcelona. The patient's serum alpha1AT level was 16 mg/dL (normal values 115-220 mg/dL). Inheritance of the PI Y barcelona was confirmed by family study. Amino acid substitution in postion 391 occurs in the C-terminal peptide region, which shows a high degree of homology with the family of serpins. Pro391 is considered to have special relevance in the secretion of alpha1AT.

Visual acuity outcomes of patients 50 years of age and older with high myopia and untreated choroidal neovascularization

OBJECTIVE

To evaluate visual outcomes of untreated submacular choroidal neovascularization (CNV) in patients 50 years of age and older with high myopia.

DESIGN

Retrospective observational case series.

PARTICIPANTS

Twenty-two eyes in 22 patients were studied. All were 50 years of age and older with myopia of 6.0 diopters (D) or greater or an axial length of 25.5 mm or greater. Patients had untreated CNV documented by clinical examination and fluorescein angiography at two medical centers between 1986 and 1997.

INTERVENTION

Demographic and clinical data were abstracted from patients' medical records.

MAIN OUTCOME MEASURE

Visual acuity at 1 year after CNV diagnosis.

RESULTS

The study included 22 eyes of 22 patients (mean age, 63.1 years; mean refraction, -11.0 D). Baseline visual acuity (VA) in the study eye was 20/40 or greater in 2 (9%) patients, 20/50 to 20/150 in 9 (41%) patients, and 20/200 or less in 11 (50%) patients. Drusen were present in seven (32%) eyes, and lacquer cracks were noted in ten (45%) eyes. Mean refractive error was -7.0 D for patients with drusen and -12.5 D for patients without drusen. Choroidal neovascularization was less than 0.25 disc diameters (DD) in 11 (50%) eyes, 0.25 to 0.5 DD in 5 (23%) eyes, and greater than 0.5 DD in 6 (27%) eyes. Visual acuity in the study eye 1 year after CNV diagnosis was 20/40 or greater in 3 (14%) patients, 20/50 to 20/150 in 3 (14%) patients, and 20/200 or less in 16 (73%) eyes. The presence of drusen was significantly associated with older age and a lower degree of myopia but was not associated with size of the CNV or visual acuity outcome.

CONCLUSION

When compared to patients younger than 50 years of age with high myopia and CNV reported in previous publications, the patients in the current series generally have poorer visual outcomes.

The role of B lymphocytes in coxsackievirus B3 infection

Coxsackieviruses are important human pathogens, frequently causing myocarditis, pancreatitis, and a variety of less severe diseases. B lymphocytes appear central to the interaction between these viruses and their mammalian hosts, because agammaglobulinemic humans, genetically incapable of antibody production, are susceptible to chronic infections by coxsackieviruses and related enteroviruses, such as poliovirus and echovirus. However, recent studies show that Type B coxsackievirus (CVB) infects B lymphocytes soon after infection, suggesting the possibility that these cells may play some role in virus dissemination and/or that the virus may be able to modulate the host immune response. We analyzed the role of B lymphocytes in CVB infection and confirmed that CVB infects B lymphocytes, and extended these findings to show that this is a productive infection involving approximately 1 to 10% of the cells; however, infectious center assays show that other splenocytes are infected at approximately the same frequency. Virus is readily detectable by in situ hybridization in the spleen of immunocompetent mice but is difficult to detect in mice deficient in B cells (BcKO mice), consistent with much of the splenic signal being the result of B cell infection. Surprisingly, given the extent of their infection, B cells express barely detectable levels of the murine coxsackievirus-adenovirus receptor (mCAR), suggesting that another means of cell entry may be used. We found no evidence of B cell depletion following CVB infection, indicating that this is not the explanation for the transient immunosuppression previously reported. Virus replication and dissemination are slightly delayed in BcKO mice, consistent with B cells' playing a role as an important early target of infection and/or a means to distribute the virus to many tissues. In addition, we show that BcKO mice recapitulate a central feature of human agammaglobulinemia: CVB establishes chronic infection in a variety of organs (heart, liver, brain, kidney, lung, pancreas, spleen). In most of these tissues the viral titers remain high (10(5)-10(8) plaque forming units (pfu) per gram of tissue) for the life of the mouse, and in several there is severe pathology, particularly severe myocardial fibrosis with ventricular dilation, reminiscent of the dilated cardiomyopathy seen in humans with chronic enteroviral myocarditis. Transfer of B and/or T cells from non-immune mice had no discernible effect, whereas equivalent transfers from immune mice often resulted in transient or permanent disappearance of detectable CVB.

Rapid on/off cycling of cytokine production by virus-specific CD8+ T cells

CD8-positive T cells protect the body against viral pathogens by two important mechanisms: production of antiviral cytokines and lysis of infected cells. Cytokine production can have both local and systemic consequences, whereas cytolytic activity is limited to infected cells that are in direct contact with T cells. Here we analyse activated CD8-positive T cells from mice infected with lymphocytic choriomeningitis virus and find that cytokines are not produced ex vivo in the absence of peptide stimulation, but that they are rapidly generated after T cells encounter viral peptides bound to the major histocompatibility complex. Remarkably, cytokine production ceases immediately upon dissociation of the T cells from their targets and resumes when antigenic contact is restored. In contrast to the 'on/off/on' cycling of cytokines, the pore-forming cytotoxic protein perforin is constitutively maintained. Our results indicate that there is differential expression of effector molecules according to whether the antiviral product is secreted (like cytokines) or stored inside the cell (like perforin). The ability to turn cytokines on and off while maintaining intracellular stores of perforin shows the versatility of the cellular immune response and provides a mechanism for maintaining effective immune surveillance while reducing systemic immunopathology.

Effect of eprosartan and losartan on uric acid metabolism in patients with essential hypertension

OBJECTIVE

The influence of angiotensin II AT-1 receptor antagonists on uric acid metabolism, and the potential differences among them with regard to this effect, remains to be precisely established. This study was designed to compare the effects of losartan and eprosartan on uric acid metabolism in patients with mild to moderate essential hypertension.

DESIGN

Randomized, double-blind, parallel-group study in hypertensive patients.

SETTING

Outpatient clinic.

PATIENTS

Following a 2- to 3-week single-blind placebo run-in period, 60 patients with sitting diastolic blood pressure > or = 95 and < or = 114 mmHg were randomized. Fifty-eight patients completed the study.

INTERVENTIONS

Patients were randomized to receive losartan 50 mg or eprosartan 600 mg once daily for 4 weeks.

MAIN OUTCOME MEASURES

The primary endpoint was the change in the ratio of urinary uric acid/creatinine in the period 0-4 h of a 24 h urine collection after 4 weeks of treatment. Secondary endpoints included 24 h urinary uric acid excretion, as well as serum urate and anti-hypertensive efficacy.

RESULTS

Mean urinary uric acid/creatinine changes from baseline were 0.14 (day 1) and 0.11 (week 4) for losartan and -0.04 for eprosartan (at both day 1 and week 4; P < 0.01 between groups at both time-points). The mean increase in 24 h urinary uric acid excretion with losartan was 0.7 mmol/24 h (25% increase from baseline) at both day 1 and week 4. No significant difference was observed in the change of serum urate levels versus baseline between both treatment groups after 4 weeks (- 23.4 and - 19.5 micromol/l for losartan and eprosartan, respectively). Patients with hyperuricaemia in both treatment groups showed similar modifications of uric acid metabolism compared with non-hyperuricaemic subjects. Blood pressure control (sitting diastolic blood pressure < 90 mmHg or < 100 mmHg with a decrease of at least 10 mmHg from baseline) was achieved in 22 patients (73%) with eprosartan and in 16 (53%) with losartan.

CONCLUSIONS

Losartan increased uric acid excretion in hypertensive patients, whilst eprosartan did not Neither AT-1 receptor antagonist substantially modified serum urate concentrations.

Sedative actions of Ternstroemia sylvatica in the male rat

Ternstroemia sylvatica is a plant reputed popularly to possess a anxiolytic properties but has not yet been systematically tested for such activity. The behavioral actions of T. sylvatica were examined using the open field test, the elevated plus-maze test, and the forced swim test in male rats. T. sylvatica (7.1 mg/kg and 14.2 mg/kg, i.p.) reduced ambulatory behavior in the open field test and cancelled the anti-immobility actions produced by desipramine (32 mg/kg, i.p.) in the forced swim test, as did diazepam. In the elevated plus-maze test, T. sylvatica (7.1 mg/kg, i.p.) failed to show anxiolytic actions. It is concluded that Ternstroemia sylvatica produces sedative effects rather than the attributed anxiolytic actions.

DNA immunization: mechanistic studies

DNA immunization works, as has been amply demonstrated in a variety of microbial and tumor models. However, the mechanisms which underpin its success remain unclear. Using intramuscular delivery of DNA, we wish to precisely define how DNA-encoded antigens induce CD8+ T-cells (most cytotoxic T-cells; CTL), CD4+ T-cells (mostly helper cells) and antibodies; and to use the accrued knowledge to rationally manipulate DNA vaccines, thus enabling us to optimize each of the above three types of immune response. We consider it likely that different mechanisms operate in each case. We have designed a DNA vaccine which induces CTL, but not antibodies. We will present evidence that CTL are induced by endogenously-synthesized protein, not by protein released from cells; and that in the absence of release of intact protein, antibodies are not induced, while CTL induction remains strong. We have used plasmid-encoded minigenes and have found that these short sequences also induce CTL; this, too, argues that CTL are induced by antigens presented following endogenous synthesis. We are attempting to determine how antigens are released from transfected cells, to interact with B-cells and induce antibodies, and are currently evaluating the CD4 responses induced by DNA vaccines.

A Colombian family with X-linked juvenile retinoschisis with three affected females finding of a frameshift mutation

X-linked retinoschisis (XLRS) is a vitreoretinal disease responsible for most cases of juvenile macular degeneration in males. Retinoschisis carrier females generally manifest no pathological symptoms. However, a large affected family from Colombia presented three affected females with typical RS phenotype similar to their 27 affected male relatives. Fundus examination as well as electroretinograms (ERG) indicate that the disease in these three affected females is as severe as in their affected male counterparts. DNA sequence analysis of the XLRS1 gene in the affected members of this family indicates a single base (G) deletion at the 639 base position (639delG). This deletion causes a frameshift during translation and results in a larger (235 amino acids) than normal peptide (224 amino acids) with grossly altered discoidin domain, which is considered critical for the cellular function of the protein. The co-segregation of this gene mutation with the RS phenotype and the RS carrier status as well as its complete absence in normal controls indicates that this genetic change is responsible for the RS pathology in this family. This (639delG) is a novel RS mutation and reported here for the first time. Furthermore, the analysis of the three affected females indicates that the RS pathology in affected females (a very rare occurrence) is due to XLRS1 mutations carried on both of their X chromosomes.

Cholesterol orientation and dynamics in dimyristoylphosphatidylcholine bilayers: a solid state deuterium NMR analysis

Proton decoupled deuterium NMR spectra of oriented bilayers made of DMPC and 30 mol % deuterated cholesterol acquired at 76.8 MHz (30 degreesC) have provided a set of very accurate quadrupolar splitting for eight C-D bonds of cholesterol. Due to the new precision of the experimental data, the original analysis by. Biochemistry. 23:6062-6071) had to be reconsidered. We performed a systematic study of the influence on the precision and uniqueness of the data-fitting procedure of: (i) the coordinates derived from x-ray, neutron scattering, or force field-minimized structures, (ii) internal mobility, (iii) the axial symmetry hypothesis, and (iv) the knowledge of some quadrupolar splitting assignments. Good agreement between experiment and theory could be obtained only with the neutron scattering structure, for which both axial symmetry hypothesis and full order parameter matrix analysis gave satisfactory results. Finally, this work revealed an average orientation of cholesterol slightly different from those previously published and, most importantly, a molecular order parameter equal to 0.95 +/- 0.01, instead of 0.79 +/- 0.03 previously found for the same system at 30 degreesC. Temperature dependence in the 20-50 degreesC range shows a constant average orientation and a monotonous decrease of cholesterol Smol, with a slope of -0.0016 K-1. A molecular order parameter of 0.89 +/- 0.01 at 30 degreesC was determined for a DMPC/16 mol % of cholesterol.

Extrusion-spheronization manufacture of Gelucire matrix beads

Theophylline extended-release spheres were prepared by extrusion-spheronization of matrix granulations previously obtained by incorporation of the drug in melted Gelucire 50/02 or Gelucire 55/18. Hydrophobic Gelucire 50/02 behaved as an inert matrix and released theophylline very slowly compared with hydrodispersible Gelucire 55/18, which acted as a hydrophilic matrix. Extrusion-spheronization was more easily accomplished with Gelucire 50/02. The use of ethanol as a wetting fluid increased the rate of drug release noticeably with Gelucire 50/02 and less so with Gelucire 55/18. The use of castor oil, in conjunction with ethanol to slow down the solvent evaporation, improved extrusion and spheronization. Castor oil decreased the drug release rate with Gelucire 50/02 and increased it with Gelucire 55/18. These phenomena were explained by the different solubilities of theophylline, Gelucire 50/02, and Gelucire 55/18 in ethanol and castor oil. When microcrystalline cellulose (Avicel CL 611) was used in the granulation matrix, extrusion was improved. The best formulation was obtained with Gelucire 55/18 and Avicel CL 611 and was wetted by a mixture of ethanol and castor oil. Regardless of the formulation, the mechanism of theophylline release appeared to be via Fickian diffusion.

Electrooptics studies of Escherichia coli electropulsation: orientation, permeabilization, and gene transfer

Fast optical transient signals are suitable approaches to the investigation of the behavior of bacteria during an electric pulse. In a previous work, by a dual approach taking advantage of a video method and a fast kinetic study of the light transmitted across a cell suspension, we showed that a field-induced orientation phenomenon was affecting the rod-shaped bacteria during the pulse (Eynard et al., 1992. Eur. J. Biochem. 209:431-436). In the present work, time courses of electro-induced responses of bacteria during a single square-wave pulse are analyzed. Observations of both the orientation step and the permeabilization process are relevant. These two steps are affected by the addition of DNA. They both obey to a first-order kinetic. The conclusion of this work is that Escherichia coli permeabilization and transformation are multistep processes: orientation (step 1) is followed by an envelope alteration (step 2), all steps being affected by plasmid addition. In the case of E. coli, a rod-shaped bacteria, the orientation process (step 1) brings the cell parallel to the field direction. The pulse duration must be longer than the orientation characteristic time (approximately 1 ms) to trigger an effective permeabilization and its associated events. The permeabilization process (step 2) is associated with a field-induced dipole effect.

Oral rizatriptan versus oral sumatriptan: a direct comparative study in the acute treatment of migraine. Rizatriptan 030 Study Group

Rizatriptan is a potent, oral, 5-HT1B/1D agonist with more rapid absorption and higher bioavailability than oral sumatriptan. It was postulated that this would result in more rapid onset of effect. This randomized, double-blind, triple-dummy, parallel-groups study compared rizatriptan 5 mg, rizatriptan 10 mg, sumatriptan 100 mg, and placebo in 1268 outpatients treating a single migraine attack. Headache relief rates after rizatriptan 10 mg were consistently higher than sumatriptan at all time points up to 2 hours, with significance at 1 hour (37% versus 28%, P = 0.010). All active agents were significantly superior to placebo with regard to headache relief and pain freedom at 2 hours (P < or = 0.001). The primary efficacy endpoint of time to pain relief through 2 hours demonstrated that, after adjustment for age imbalance, rizatriptan 10 mg had earlier onset than sumatriptan 100 mg (P = 0.032; hazard ratio 1.21). Rizatriptan 10 mg was also superior to sumatriptan on pain-free response (P = 0.032), reduction in functional disability (P = 0.015), and relief of nausea at 2 hours (P = 0.010). Significantly fewer drug-related clinical adverse events were reported after rizatriptan 10 mg (33%, P = 0.014) compared with sumatriptan 100 mg (41%). We conclude that rizatriptan 10 mg has a rapid onset of action and relieves headache and associated symptoms more effectively than sumatriptan 100 mg.

Is the femoral cannulation for minimally invasive aortic valve replacement necessary?

INTRODUCTION

Minimally invasive cardiac surgery through a small transverse sternotomy is a new promising technique that can be considered an alternative in most cases to aortic valve replacement thus reducing surgical trauma and subsequent time of hospitalization. The need to avoid the risks associated with femoro-femoral bypass has lead to the interest in aortic valve replacement (AVR) operations without femoral vessels cannulation. We want to emphasize a few important points of our technique, which differs somewhat from the one applied by Cosgrove and associates.

OBJECTIVE

This study details the approach to the minimally invasive AVR as first described by. Cosgrove et al. without standard femoral cannulation and points out our preliminary clinical experience.

PATIENTS AND METHODS

From October 1996 to May 1997 we have operated on 25 patients using minimally invasive AVR (MI-AVR) In 23 cases, access through transverse sternotomy as described by Cosgrove et al., was performed. In two additional cases the chest is opened via a mini-median sternotomy with an 'L'-shape extending from the sternal notch to the superior edge of the third interspace. Twenty-three patients underwent AVR through transverse sternotomy. The male/female ratio was 13:10. The mean age was 67 years (range 45-78 years). Seventy-four percent of the patients were over 65. Predominantly, in 43% of cases aortic valve stenosis and in 25% of cases aortic valve regurgitation isolated is presented. In 19 cases, a 10-cm transverse incision is performed over the second interspace. Likewise, in four cases over the third interspace according to the thorax morphology and length of the ascending aorta assessed by chest X-ray films. By convention, cannulation of the ascending aorta and right atrial appendage was performed as usual. In contrast, in one patient (5.5%), cannulation was placed in the superior vena cava and right common femoral vein into the inferior vena cava. In the present series, 15 mechanical prostheses and eight bioprostheses whose used sizes were 19, 21,23, and 25 mm in diameter were placed in four, nine, nine, and one of the cases, respectively. All patients underwent AVR electively and a transesophageal echocardiography probe is made.

RESULTS

During surgery, conversion to median sternotomy was not required in any patient. Mean aortic cross-clamp time was 68 min (range 38-90 min). Mean total bypass time was 87 min (range 50-120 min). Mean postoperative bleeding was 434 ml. (range 200-850 ml). Perioperative blood transfusion was required in 17% of the patients. Mean mechanical ventilation time was 7.3 h (range 3-24 h), with a mean ICU stay of 18 h. Mean postoperative hospital stay was 4.5 days (range 3-10 days). In all cases, transthoracic and transesophageal echocardiography were performed postoperatively Prosthetic valve dysfunction was not observed. On the other hand, just one patient (4%) died 5 days after operation due to sudden cardiac death. Further, in two patients (8%), during follow-up, pericardial effusion is detected. In one case, cardiac tamponade with hemodynamic instability required a pericardial window procedure. In addition, in two patients (8%), non-infectious sternal dehiscence required reinforced sternal closure.

CONCLUSIONS

Minimally invasive AVR surgery without femoral vessel cannulation is a safe procedure with less surgical aggression. After a learning curve, benefits on fast-track programs will be accomplished.