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.

Agreement between hysterosalpingography and laparoscopic chromopertubation in assessment of tubal patency

BACKGROUND

To assess the agreement between tubal patency assessed by laparoscopy with chromopertubation and by hysterosalpingography using contrast media.

SETTING

University Medical School.

PATIENTS

314 consecutive women subjected to laparoscopy and hysterosalpingography for an infertility study.

DESIGN

Prospective study.

METHODS

Chromopertubation using Methylen blue dye, performed on days 20-24. Hysterosalpingography performed on days 7-10 with water soluble contrast.

MAIN OUTCOME MEASURE

Kappa coefficient calculation.

RESULTS

Kappa coefficient ranged from 0.40 to 0.36, depending on the categories analyzed, corresponding to a fair agreement.

CONCLUSION

The diagnosis of tubal factor requires that both tubal patency tests (Hysterosalpingography and laparoscopy) show an abnormal patency. When one of the aforementioned tests is normal, performing the second one has little clinical advantage. However, it is suggested that when there is a discordant patency the pregnancy rates could be somewhat reduced.

Influence of pretreatment lesions on histologic response to interferon therapy in chronic hepatitis C

We have assessed the predictive value of the grade of pretreatment liver lesions on histologic response to interferon therapy in patients with chronic hepatitis C. In 93 patients with chronic hepatitis C virus (HCV) infection who showed an initial response to interferon therapy, HCV RNA load and serum aminotransferase levels together with grade of liver histologic lesions were assessed at baseline and 6 months after treatment cessation. Regression of portal and periportal necroinflammation was observed only in sustained responders (normalization of aminotransferase levels and HCV RNA clearance). Neither short-term response nor the absence of virus was associated with significant histologic changes in the liver biopsies. Logistic regression analysis showed that pretreatment histologic lesion was an independent predictive factor of biologic response in the histologic regression of lesions 6 months after cessation of interferon treatment. In conclusion, a dense inflammatory necrotic activity is a positive predictor of histologic response in interferon-treated patients with HCV.

DNA immunization with minigenes: low frequency of memory cytotoxic T lymphocytes and inefficient antiviral protection are rectified by ubiquitination

Our previous studies have shown that isolated cytotoxic T lymphocyte (CTL), B-cell, and T-helper epitopes, for which we coined the term minigenes, can be effective vaccines; when expressed from recombinant vaccinia viruses, these short immunogenic sequences confer protection against a variety of viruses and bacteria. In addition, we have previously demonstrated the utility of DNA immunization using plasmids encoding full-length viral proteins. Here we combine the two approaches and evaluate the effectiveness of minigenes in DNA immunization. We find that DNA immunization with isolated minigenes primes virus-specific memory CTL responses which, 4 days following virus challenge, appear similar in magnitude to those induced by vaccines known to be protective. Surprisingly, this vigorous CTL response fails to confer protection against a normally lethal virus challenge, although the CTL appear fully functional because, along with their high lytic activity, they are similar in affinity and cytokine secretion to CTL induced by virus infection. However this DNA immunization with isolated minigenes results in a low CTL precursor frequency; only 1 in approximately 40,000 T cells is epitope specific. In contrast, a plasmid encoding the same minigene sequences covalently attached to the cellular protein ubiquitin induces protective immunity and a sixfold-higher frequency of CTL precursors. Thus, we show that the most commonly employed criterion to evaluate CTL responses-the presence of lytic activity following secondary stimulation-does not invariably correlate with protection; instead, the better correlate of protection is the CTL precursor frequency. Recent observations indicate that certain effector functions are active in memory CTL and do not require prolonged stimulation. We suggest that these early effector functions of CTL, immediately following infection, are critical in controlling virus dissemination and in determining the outcome of the infection. Finally, we show that improved performance of the ubiquitinated minigenes most probably requires polyubiquitination of the fusion protein, suggesting that the enhancement results from more effective delivery of the minigene to the proteasome.

Hepatitis delta genotypes in chronic delta infection in the northeast of Spain (Catalonia)

BACKGROUND/AIMS

Based on genetic analysis of variants obtained around the world, three genotypes of the hepatitis delta virus have been defined. Hepatitis delta virus variants have been associated with different disease patterns and geographic distributions. To determine the prevalence of hepatitis delta virus genotypes in the northeast of Spain (Catalonia) and the correlation with transmission routes and clinical disease, we studied the nucleotide divergence of the consensus sequence of HDV RNA obtained from 33 patients with chronic delta hepatitis (24 were intravenous drug users and nine had no risk factors), and four patients with acute self-limited delta infection.

METHODS

Serum HDV RNA was amplified by the polymerase chain reaction technique and a fragment of 350 nucleotides (nt 910 to 1259) was directly sequenced.

RESULTS

Genetic analysis of the nucleotide consensus sequence obtained showed a high degree of conservation among sequences (93% of mean). Comparison of these sequences with those derived from different geographic areas and pertaining to genotypes I, II and III, showed a mean sequence identity of 92% with genotype I, 73% with genotype II and 61% with genotype III. At the amino acid level (aa 115 to 214), the mean identity was 87% with genotype I, 63% with genotype II and 56% with genotype III. Conserved regions included the RNA editing domain, the carboxyl terminal 19 amino acids of the hepatitis delta antigen and the polyadenylation signal of the viral mRNA.

CONCLUSIONS

Hepatitis delta virus isolates in the northeast of Spain are exclusively genotype I, independently of the transmission route and the type of infection. No hepatitis delta virus subgenotypes were found, suggesting that the origin of hepatitis delta virus infection in our geographical area is homogeneous.

Dexamethasone induces altered binding of regulatory factors to HLA class I enhancer sequence in MCF-7 breast tumour cell line

Several reports have shown the importance of MHC class I antigens in enabling the host to regulate tumour growth in vivo. Glucocorticoid hormones have strong immunosuppressive effects and are known regulators of gene transcription. In this work we studied the expression of major histocompatibility complex (MHC) class I antigens in three breast carcinoma cell lines before and after treatment with the synthetic glucocorticoid dexamethasone. HLA class I expression in the cell line MCF-7 was down-regulated in the presence of dexamethasone. This down-modulation of expression appeared to be mediated by transcriptional mechanisms, as revealed by HLA class I mRNA levels. To elucidate the basis of MHC class I down-regulation by dexamethasone, we examined transcriptional-factor-binding activity to the HLA class I regulatory element or enhancer A by electrophoretic-mobility-shift assays, using synthesized oligonucleotides corresponding to upstream conserved sequences of MHC class I genes. Our results showed that dexamethasone induced a different binding to the MHC class I regulatory elements in the MCF-7 cell line from that of the other cell lines included in our study. MCF-7 cells presented a strong decrease in previous factor-binding activity to the CRE II probe (H2RIIBP-like binding activity) and a new factor-binding activity was apparent. On the other hand, CRE I region showed an increase in KBF1-factor-binding activity. These results suggest that glucocorticoids down-modulate the expression of MHC class I antigens by altering the binding to the enhancer A sequence. In addition, this down-modulation may affect the regulation of tumour growth by the host's immune system.

Youth counseled for HIV testing at school- and hospital-based clinics

The prevalence of human immunodeficiency virus (HIV) in adolescents is difficult to assess as few adolescents consent to testing. This prospective study characterized urban youth requesting HIV testing at two types of health settings, inner-city school-based and hospital-based clinics. Data were obtained on 1652 inner-city youths aged 13 to 19 years who consented to individualized HIV counseling and testing from January 1993 to January 1994. Identified risks for HIV included sexual activity, sexually transmitted disease (STD) history, and substance use by self-report during a confidential structured interview. Data were analyzed using chi-squared analysis. Of the 1652 youth who were counseled, 1602 were from hospital-based clinics. A total of 827 (50%) requested HIV testing. Females accounted for the majority of youth who underwent counseling (79%) and requested HIV testing (75%). However, once counseled, males were more likely to be tested. Risk factors differed by gender; females were more likely to report STDs and marijuana use, and males more likely to report alcohol and cocaine use. These results indicate a need to identify developmentally appropriate methods to educate and counsel youth about HIV that will lead to more youth willing to be tested. School-based clinics may provide easier access than traditional health models for confidential HIV services.

c-myc, c-erb-B2, nm23 and p53 expression in human endometriosis

We studied the expression of oncogenes and tumor-suppressor genes in human endometriosis in a retrospective pilot study. Sixteen patients with histologically verified pelvic endometriosis at the university-based tertiary care referral center were studied. Immunohistochemical determination of c-myc, c-erb-B2, nm23 and p53 expression in archival, paraffin-embedded pathological samples were used from patients operated upon for pelvic endometriosis. c-myc was expressed in 8/15 cases (53.3%). nm23 was expressed in 7/16 cases (43.7%). c-erb-B2 and p53 reactivity was undetectable in the samples studied. The c-myc oncogene and nm23 are overexpressed in many cases of endometriosis, and may play a still undefined role in its pathogenesis. Immuno-histochemistry is a useful tool for the study of oncogenic activation in this disease.

"H" reflex as a measure of subclinical uremic polyneuropathy in children with chronic renal failure

Uremic polyneuropathy (UPNP) is a serious complication of chronic renal failure (CRF) in adults; however, its prevalence is unknown in the pediatric population. An easy-to-perform maneuver for its detection in children is the evaluation of "H" reflex. The objective of this study was to validate the usefulness of the "H" reflex maneuver for the diagnosis of UPNP in pediatric dialysis patients for CRF. Thirty-seven CRF patients were paired with healthy controls by age and sex. The patients were being treated with dialysis or one of its variants. Information was obtained regarding diagnosis, duration, and control of dialysis. Neurological examination was performed, conduction velocities in sensory and motor nerves were measured, and "H" reflex elicited bilaterally. Peripheral polyneuropathy was determined by the presence of at least two nerves with alterations in latency and/or conduction velocities. It was found that 59.4% (22/37) of the children with CRF treated with dialysis developed UPNP, 17 with ambulatory peritoneal dialysis, and 5 with hemodialysis. There was no difference in diagnosis, duration of dialysis, or control of the same in these patients from other CRF patients who did not have UPNP. All patients were clinically asymptomatic. "H" reflex showed a sensibility of 44%, a specificity of 87%, a predictive value positive of 66%, and a predictive value negative of 76%, when measured to 28 msec. With a 30 msec duration specificity rises to 95%. UPNP presents asymptomatically in pediatric patients. "H" reflex is an adequate screening test for the selection of pediatric patients to be tested further.

DNA immunization: ubiquitination of a viral protein enhances cytotoxic T-lymphocyte induction and antiviral protection but abrogates antibody induction

DNA immunization can induce cytotoxic T lymphocytes (CTL), antibodies, and protection against microbial challenge. The underlying mechanisms remain obscure and must be understood to permit rational manipulation and optimization of the technique. We set out to enhance the intracellular degradation of a viral antigen, with the intent of improving antigen entry into, and presentation by, the class I major histocompatibility complex pathway. We achieved this goal by cotranslational ubiquitination of a plasmid-encoded viral antigen, lymphocytic choriomeningitis virus (LCMV) nucleoprotein (NP). We show that native NP is very stable in cell culture, while the ubiquitinated product is so rapidly degraded that it is barely detectable. This rapid degradation leads to more efficient sensitization of target cells in an in vitro cytotoxicity assay, consistent with enhanced antigen presentation, and both degradation and target cell recognition are blocked by a proteasome inhibitor. We have used the plasmid for in vivo studies and find that, remarkably, ubiquitination leads to a complete abrogation of antibody responses, presumably because the encoded protein is so rapidly and completely degraded that insufficient antigen remains to interact appropriately with B cells. In contrast, in vivo CTL induction is improved by ubiquitination of NP. That CTL are induced at all by this rapidly degraded protein may shed light on the mechanism by which CTL are induced by DNA immunization; it has been suggested that CTL induction following intramuscular DNA injection results not from antigen presentation by cells taking up and expressing the DNA but rather from uptake of soluble protein by specialized antigen-presenting cells (APC). It appears to us unlikely that the ubiquitinated protein could function in this manner, since it is so rapidly degraded in vitro and fails to induce antibodies in vivo. Finally, the ubiquitinated protein confers markedly enhanced protection against LCMV challenge. Mice immunized with a plasmid encoding NP show approximately 100-fold reductions in virus titers compared to controls, while mice immunized with a plasmid encoding the ubiquitinated NP show reductions in virus load of at least 5 x 10(4)- to 5 x 10(5)-fold. This is by far the most effective DNA vaccine that we have yet designed. Ubiquitination therefore may improve DNA immunization, but caution is warranted, since immunity to many microbes depends on induction of good humoral immunity, and we show here that this may be prevented by ubiquitination of the encoded protein.