Polymorphisms of the cell surface receptor control mouse susceptibilities to xenotropic and polytropic leukemia viruses

The differential susceptibilities of mouse strains to xenotropic and polytropic murine leukemia viruses (X-MLVs and P-MLVs, respectively) are poorly understood but may involve multiple mechanisms. Recent evidence has demonstrated that these viruses use a common cell surface receptor (the X-receptor) for infection of human cells. We describe the properties of X-receptor cDNAs with distinct sequences cloned from five laboratory and wild strains of mice and from hamsters and minks. Expression of these cDNAs in resistant cells conferred susceptibilities to the same viruses that naturally infect the animals from which the cDNAs were derived. Thus, a laboratory mouse (NIH Swiss) X-receptor conferred susceptibility to P-MLVs but not to X-MLVs, whereas those from humans, minks, and several wild mice (Mus dunni, SC-1 cells, and Mus spretus) mediated infections by both X-MLVs and P-MLVs. In contrast, X-receptors from the resistant mouse strain Mus castaneus and from hamsters were inactive as viral receptors. These results suggest that X-receptor polymorphisms are a primary cause of resistances of mice to members of the X-MLV/P-MLV family of retroviruses and are responsible for the xenotropism of X-MLVs in laboratory mice. By site-directed mutagenesis, we substituted sequences between the X-receptors of M. dunni and NIH Swiss mice. The NIH Swiss protein contains two key differences (K500E in presumptive extracellular loop 3 [ECL 3] and a T582 deletion in ECL 4) that are both required to block X-MLV infections. Accordingly, a single inverse mutation in the NIH Swiss protein conferred X-MLV susceptibility. Furthermore, expression of an X-MLV envelope glycoprotein in Chinese hamster ovary cells interfered efficiently with X-MLV and P-MLV infections mediated by X-receptors that contained K500 and/or T582 but had no effect on P-MLV infections mediated by X-receptors that lacked these amino acids. In contrast, moderate expression of a P-MLV (MCF247) envelope glycoprotein did not cause substantial interference, suggesting that X-MLV and P-MLV glycoproteins interfere nonreciprocally with X-receptor-mediated infections. We conclude that P-MLVs have become adapted to utilize X-receptors that lack K500 and T582. A penalty for this adaptation is a reduced ability to interfere with superinfection. Because failure of interference is a hallmark of several exceptionally pathogenic retroviruses, we propose that it contributes to P-MLV-induced diseases.

Volatile release from aqueous solutions under dynamic headspace dilution conditions

Static equilibrium was established between the gas phase (headspace) and an unstirred aqueous phase in a sealed vessel. The headspace was then diluted with air to mimic the situation when a container of food is opened and the volatiles are diluted by the surrounding air. Because this first volatile signal can influence overall flavor perception, the parameters controlling volatile release under these conditions are of interest. A mechanistic model was developed and validated experimentally. Release of compounds depended on the air-water partition coefficient (K(aw)) and the mass transport in both phases. For compounds with K(aw) values <10(-)(3), K(aw) was the factor determining release rate. When K(aw) was >10(-)(3), mass transport in the gas phase became significant and the Reynolds number played a role. Because release from packaged foods occurs at low Reynolds numbers, whereas most experiments are conducted at medium to high Reynolds numbers, the experimentally defined profile may not reflect the real situation.

Aortic root dilatation in young men with normally functioning bicuspid aortic valves

OBJECTIVE

To evaluate the dimensions of the aortic root in a selected population of young males with isolated normally functioning bicuspid aortic valve.

DESIGN AND SETTING

Echocardiographic and Doppler evaluation of conscripts with bicuspid aortic valve at the time of military pre-enrolment screening in two military hospitals.

SUBJECTS AND METHODS

66 consecutive young men with a normally functioning bicuspid aortic valve were studied to assess aortic size at four aortic levels: annulus, sinuses of Valsalva, supra-aortic ridge, and proximal ascending aorta; 70 consecutive normal young subjects, matched for age and body surface area, were used as controls.

RESULTS

In men with a bicuspid aortic valve, the diameter of the aortic root was significantly larger than in controls at the sinuses (3.16 (0.37) v 2.87 (0.31) cm, p < 0.001), at the supra-aortic ridge (2.64 (0.46) v 2.47 (0.28) cm, p = 0.01), and at the level of the proximal ascending aorta (3.12 (0.48) v 2.69 (0.28) cm, p < 0.001). The prevalence of aortic root dilatation was 7.5% at the annulus (5/66), 19.6% at the sinuses (13/66), 15% at the supra-aortic ridge (10/66), and 43.9% at the ascending aorta (29/66); 32 subjects (48%) had aortic root dimensions comparable with controls, while 34 (52%) had definitely abnormal aortic root dimensions.

CONCLUSIONS

Aortic root enlargement in people with a bicuspid aortic valve occurs independently of haemodynamic abnormalities, age, and body size. However, there appear to be different subgroups of young adults with bicuspid aortic valves, one of which is characterised by aortic dilatation, possibly caused by a congenital abnormality of the aortic wall.

Epidemiology and cost analysis of varicella in Italy: results of a sentinel study in the pediatric practice. Italian Sentinel Group on Pediatric Infectious Diseases

BACKGROUND

Describing the epidemiology of varicella is relevant to the development of specific prevention strategies and to building up of economic models evaluating the cost:efficiency ratios of these strategies.

AIM

Our study was designed to describe the epidemiology of chickenpox among Italian children and to assess the resulting economic and health burden on the country.

METHODS

Thirty-nine Italian pediatricians participated in a sentinel network on pediatric infectious diseases representing a total pediatric population of 30 168 children. Each case of varicella observed from January through December, 1997, was recorded. Economic analysis was conducted from the societal point of view. All costs were broken down into two groups: direct and indirect costs.

RESULTS

A total of 1599 cases of varicella were reported among children 0 to 14 years old. There were 1266 primary cases (mean age, 4.5 +/- 2 years) and 333 secondary cases (mean age, 3.6 +/- 3.2 years). The global incidence of chickenpox was 51.01/1000/year. Complications were seen in 56 cases (3.5%). Drugs were prescribed in 672 cases. A group of adults (364 susceptible and 193 with uncertain status) were exposed to primary cases. Seventy (12.5%) were eventually infected among whom there were 4 pregnant women. For pediatric patients an average cost of $146.90 (250 400 lire) was estimated; this is largely accounted for by indirect costs.

CONCLUSIONS

The epidemiology of varicella in Italy is consistent with that found in previous studies in industrialized countries. Severe complications did not occur in our population. We believe that the health arguments in favor of universal vaccination of children > 18 months of age do not differ in our own country from those of other industrialized nations. Our data could now be incorporated into pharmacoeconomic models to establish cost-efficient strategies for Italy.

Pseudomonas aeruginosa: a survey of resistance in 136 hospitals in Spain. The Spanish Pseudomonas aeruginosa Study Group

We carried out a nationwide study with all of the isolates of Pseudomonas aeruginosa collected in a week in 136 hospitals in Spain. The data on 1,014 isolates included resistance to the following antimicrobials: piperacillin-tazobactam, 7%; meropenem, 8%; amikacin, 9%; tobramycin, 10%; piperacillin, 10%; ticarcillin, 13%; imipenem, 14%; ceftazidime, 15%; cefepime, 17%; ciprofloxacin, 23%; aztreonam, 23%; ofloxacin, 30%; gentamicin, 31%. The most frequent serotypes were O:1 (25.1%), O:4 (21.6%), and O:11 (11.3%).

Genetically engineered antibodies in gene transfer and gene therapy

Our ability to produce and engineer human monoclonal antibodies provides a basis for the development of novel therapeutical strategies against a variety of diseases. These strategies not only include improved passive immunotherapy but also more sophisticated antibody-based gene therapies involving gene transfer approaches. Four of the major applications of antibody gene engineering in the field of gene therapy are reviewed here. These are (1) the redefinition of viral vector tropism of infection for better transduction of cells of therapeutical interest, (2) the grafting of new cell recognition activities to effector cells of the immune system to kill cancer and pathogen-infected cells, (3) the inhibition of cellular and viral functions through intracellular expression of antibody-derived molecules, and (4) the systemic delivery of therapeutic monoclonal antibodies by non-B cells in living organisms.

Postextrasystolic potentiation echocardiography in predicting reversible myocardial dysfunction by surgical coronary revascularization

Sustained inotropic stimulation, such as dobutamine infusion, has the potential to cause an additional contractile deterioration in viable but chronically hypoperfused and dysfunctioning myocardium, by inducing ischemia. Postextrasystolic potentiation (PESP) represents a potent inotropic stimulus without risk of provoking ischemia, as it is instantaneous. In this study, we assessed the role of PESP-echocardiographic examination in predicting the recovery of regional contractility after coronary revascularization. We examined 105 consecutive patients with multivessel coronary artery disease who were candidates for bypass surgery; 79 were included in this prospective study. Preoperative reversibility of contractile dysfunction in asynergic myocardial regions was determined by PESP, with a coupling interval of 500 msec decreasing to 300 msec, with a progressive decrease by 10 msec. The examination was accompanied by continuous 2-dimensional (2D) echocardiographic monitoring. The assessed sensitivity and specificity were 92% and 87%, respectively; the predictive accuracy was 90%. These results demonstrated that PESP echocardiography is a useful and cost-effective method for identifying viable myocardium in patients undergoing myocardial revascularization.

Cell targeting by murine retroviral vectors

Gene therapy involves the transfer of new genetic material to cells of individuals with the aim of conferring a therapeutical benefit. Theoretically, gene therapy can be used to treat a variety of life-threatening disorders, such as inherited genetic diseases, cancer, chronic viral infections as well as a number of other severe diseases which are not treatable at present. To this aim, both efficient gene delivery techniques and controlled gene expression systems are required. Engineered murine retroviruses are the most widely used vectors for stable clinical gene transfer because of their ability to integrate--along with the transgenes they are engineered to carry--into the genome of infected cells. However, this technology still suffers from a number of drawbacks and limitations. Particularly, the ability to target cells of therapeutic interest together with the controlled expression of transferred genes would improve both the efficiency and the safety of retroviral vectors. Such improvements would additionally allow the development of new animal models of human diseases as well as enable more fundamental investigations in the fields of oncogenesis and developmental biology.

Systemic long-term delivery of antibodies in immunocompetent animals using cellulose sulphate capsules containing antibody-producing cells

Implantation of capsules containing antibody-producing cells into patients would potentially permit systemic long-term delivery of antibodies and might, thus, be useful in the development of surveillance treatments for cancers and severe viral diseases. We show that cellulose sulphate (CS) capsules containing hybridoma cells, when implanted subcutaneously or in the intraperitoneal cavity, can be used for delivering monoclonal antibodies into the blood-stream of immunocompetent mice for at least several months. In contrast to capsules implanted into the intraperitoneal cavity, which remain mobile and nonvascularized, capsules implanted under the skin form neo-organs which become vascularized within days. This may explain the higher blood concentration of the antibody we have observed in the latter case. Importantly, neither an isolating fibrosis nor an obvious inflammatory response was detected at the capsule implantation sites during observation periods as long as 10 months. Finally, no anti-idiotypic immune response against the ectopically delivered antibody was shown to occur. This rules out any potent adjuvant effect of the cellulose sulphate matrix that might have stimulated a neutralizing humoral response. Taken together, our data indicate that encapsulation of antibody-producing cells into CS might be used in antibody-based gene/cell therapy approaches.

[Endovascular treatment of dural arteriovenous fistulas with medullary venous drainage. Experience with 18 patients]

INTRODUCTION AND OBJECTIVE

The authors report a series of 18 patients with myelopathy who were diagnosed of dural arteriovenous fistulas with venous medullary drainage (DFVMd). Purpose was to assess the effectiveness, initial and long term, of embolization, as the initial treatment, using polyvinyl alcohol particles (PVA) and liquid adhesives. N-butyl-cyanoacrylate (NBCA).

MATERIAL AND METHODS

Magnetic resonance images were obtained in all patients showing spinal cord tissue changes consistent with an isquemic process secondary to venous hypertension. All 18 patients showed initially an improvement in clinical symptoms, demonstrating previous MR images resolution.

RESULTS

The neurological status of 8 patients subsequently deteriorated with angiographically proven recurrences of their DFVMd. These patients underwent a second successful embolization procedure using NBVA. PVA embolization is long term ineffective and is not without risk. Endovascular treatment is less invasive than surgery, its morbidity is less, and it ensures earlier recovery for the patients. If embolization has failed, surgery can still be done.

CONCLUSIONS

We recommend that NBVA embolization be the initial treatment of choice for DFVMd if referring the patient to an experienced interventional Neuroradiology unit is available. Careful clinical and neurologic examination is necessary to establish the diagnosis of DFVMd. Finally, we strongly recommend that patients be followed closely and aggressively. Periodic clinical and radiologic assessments, including MR and spinal angiography, are essential to achieve complete cure.

Subcoracoid dislocation of the distal end of the clavicle. A case report

Subcoracoid dislocation of the outer end of the clavicle in association with an acromial fracture is a rare injury usually produced by high energy trauma that moves the clavicle posterior to the conjoined tendon and inferior to the coracoid process. To restore the acromioclavicular joint, open reduction is needed. After the reduction is accomplished, the clavicle has to be stabilized with a coracoclavicular screw. The acromial fracture can be reduced and held with nonabsorbable sutures placed through the bone. To avoid osteolysis of the distal end of the clavicle and to be able to repair the torn ligaments, treatment should not be delayed.

Myocardial dysfunction and adrenergic cardiac innervation in patients with insulin-dependent diabetes mellitus

BACKGROUND

Insulin-dependent diabetes mellitus (IDDM) is associated with an increased incidence of heart failure due to several factors, and in some cases a specific cardiomyopathy has been suggested.

OBJECTIVES

This study sought to assess the mechanisms of exercise-induced left ventricular (LV) dysfunction in asymptomatic patients with IDDM in the absence of hypertensive or coronary artery disease.

METHODS

Fourteen consecutive patients with IDDM were enrolled (10 men, 4 women; mean [+/- SD] age 28.5 +/- 6 years); 10 healthy subjects matched for gender (7 men, 3 women) and age (28.5 +/- 3 years) constituted the control group. LV volume, LV ejection fraction (LVEF) and end-systolic wall stress were calculated by two-dimensional echocardiography at rest and during isometric exercise. LV contractile reserve was assessed by post-extrasystolic potentiation (PESP) obtained by transesophageal cardiac electrical stimulation and dobutamine infusion. Myocardial iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy was performed to assess adrenergic cardiac innervation.

RESULTS

Diabetic patients were classified into group A (n = 7), with an abnormal LVEF response to handgrip (42 +/- 7%), and group B (n = 7), with a normal response (72 +/- 8%). Baseline LVEF was normal in both group A and B patients (60 +/- 6% vs. 61 +/- 7%, p = NS). In group A patients, the LV circumferential wall stress-LVEF relation showed an impairment in LVEF disproportionate to the level of LV afterload. No significant changes in LVEF occurred during dobutamine (60 +/- 6% vs. 64 +/- 10%, p = NS), whereas PESP significantly increased LVEF (60 +/- 6% vs. 74 +/- 6%, p < 0.001); PESP at peak handgrip normalized the abnormal LVEF (42 +/- 7% vs. 72 +/- 5%, p < 0.001); and MIBG uptake normalized for body weight or for LV mass was lower than that in normal subjects (1.69 +/- 0.30 vs. 2.98 +/- 0.82 cpm/MBq per g, p = 0.01) and group B diabetic patients (vs. 2.79 +/- 0.94 cpm/MBq per g, p = 0.01). Finally, a strong linear correlation between LVEF at peak handgrip and myocardial MIBG uptake normalized for LV mass was demonstrated in the study patients.

CONCLUSIONS

Despite normal contractile reserve, a defective blunted recruitment of myocardial contractility plays an important role in determining exercise LV dysfunction in the early phase of diabetic cardiomyopathy. This abnormal response to exercise is strongly related to an impairment of cardiac sympathetic innervation.

Study to determine the ability of clinical laboratories to detect antimicrobial-resistant Enterococcus spp. in Buenos Aires, Argentina

Few reports of vancomycin-resistant enterococci have appeared outside the USA. Therefore, we evaluated the ability of five laboratories in Buenos Aires, Argentina, to perform susceptibility testing using the disk diffusion method. Laboratories had difficulty identifying the low- and intermediate-level vancomycin-resistant phenotypes. This suggests that the disk diffusion method used by laboratories abroad may fail to detect some vancomycin-resistant enterococci.

Towards efficient cell targeting by recombinant retroviruses

Efficient human gene therapy will rely on efficient gene delivery systems. To date, recombinant, engineered retroviruses are the most widely used vectors for stable clinical gene transfer. However, this technology still suffers from a number of drawbacks that limit its application. The ability to target cells of therapeutic interest, in particular, would improve both the efficiency and the safety of retroviral vectors. It might also allow the development of new animal models of human diseases and probably extend the scope of gene therapy itself.

Postextrasystolic potentiation and dobutamine echocardiography in predicting recovery of myocardial function after coronary bypass revascularization

BACKGROUND

Identification of viable but hibernating myocardium remains a relevant issue in the current era of myocardial revascularization. Echocardiography can be helpful in detecting reversible contractile dysfunction and optimizing the selection of patients for coronary bypass surgery.

METHODS AND RESULTS

Eighty-four consecutive candidates for bypass surgery with chronic multivessel coronary artery disease were screened, and 60 were included in this prospective study. Preoperative evaluation of a reversible contractile dysfunction in asynergic myocardial regions was performed by dobutamine infusion at 5 (low dose) and 10 (intermediate dose) microg x kg(-1) x min(-1) with each stage lasting at least 5 minutes; postextrasystolic potentiation (PESP), with a coupling interval ranging from 500 to 300 ms with a progressive 10-ms decrease; or a combination of both dobutamine infusion and PESP. Sensitivity (92% versus 86%) and predictive accuracy (89% versus 84%) were higher with PESP than dobutamine (P=.009 and P=.001, respectively), but the combination did not improve sensitivity or accuracy. Dobutamine induced ischemic dysfunction in 15% of patients at the intermediate dose; however, the low dose resulted in loss of sensitivity.

CONCLUSIONS

PESP echocardiography is a useful and cost-effective method to identify viable myocardium in patients with multivessel coronary disease undergoing revascularization and is more sensitive and accurate than dobutamine infusion.

Evaluation of the efficacy and tolerability of nitrendipine in reducing both pressure and left ventricular mass in hypertensive type 2 diabetic patients

OBJECTIVE

To evaluate the efficacy and tolerability of nitrendipine in comparison with captopril in hypertensive diabetic patients with left ventricular hypertrophy (LVH).

RESEARCH DESIGN AND METHODS

A total of 75 patients enrolled in this study presented stable type 2 diabetes (not treated with insulin) and mild-to-moderate hypertension with a left ventricular mass > or = 75 g/m2 by two-dimensional echocardiography. After a 4-week washout period, 38 patients were assigned to treatment with captopril, and 37 patients to nitrendipine (random allocation). The duration of follow-up was 36 weeks.

RESULTS

Patients of both groups were similar with regard to the duration of diabetes and hypertension, systolic and diastolic blood pressure at rest, degree of LVH, metabolic control, and albumin excretion rate (AER). Both drugs were equally effective in reducing systolic and diastolic blood pressure (captopril: from 165 +/- 13/100 +/- 4 to 147 +/- 11/87 +/- 4 mmHg; nitrendipine: from 167 +/- 17/100 +/- 5 to 143 +/- 9/86 +/- 4 mmHg; P < 0.05) and in reversing LVH (nitrendipine: from 87 +/- 2 to 81 +/- 1 g/m2; captopril: from 89 +/- 2 to 85 +/- 2 g/m2; P = 0.0001). Neither the left ventricular end-diastolic volume index nor the left ventricular ejection fraction changed significantly during the treatment period.

CONCLUSION

Nitrendipine is as effective as captopril in reducing both systolic and diastolic blood pressure and in reversing LVH. Neither drug showed any negative side effects on fasting plasma glucose and glycated hemoglobin (HbA1c) levels, and both maintain constant AERs.

In vitro and in vivo secretion of cloned antibodies by genetically modified myogenic cells

In vivo production of recombinant antibodies by engineered cells may have applications for gene therapy of certain cancers and of certain severe viral diseases. It would also permit the development of new animal models of autoimmune diseases and new approaches for in vivo ablation of specific cell types for fundamental purposes. Using gene transfer of an anti-human thyroglobulin monoclonal antibody, we show here that several cell types permitting autologous grafting of genetically engineered cells are efficiently able to secrete antibodies in vitro. Those cells include skin fibroblasts, hepatocytes, and myogenic cells. We also show that the secreted antibodies display an affinity for the antigen close to that of the parental antibody, with, however, slight differences varying according to the cell type. This indicates that the foldings of antigen combining sites of antibodies produced in B cell- and non-B cell contexts are very similar. Finally, we report that, when implanted in the forelimb of a mouse, genetically modified myogenic cells are able to secrete antibodies for at least 4 months. Taken together, our observations point to the notion that genetic modification of patient cells may be used for long-term antibody-based gene therapies.

Transcription factor Sp1 is essential for early embryonic development but dispensable for cell growth and differentiation

Transcription factor Sp1 has been implicated in the expression of many genes. Moreover, it has been suggested that Sp1 is linked to the maintenance of methylation-free CpG islands, the cell cycle, and the formation of active chromatin structures. We have inactivated the mouse Sp1 gene. Sp1-/- embryos are retarded in development, show a broad range of abnormalities, and die around day 11 of gestation. In Sp1-/- embryos, the expression of many putative target genes, including cell cycle-regulated genes, is not affected, CpG islands remain methylation free, and active chromatin is formed at the globin loci. However, the expression of the methyl-CpG-binding protein MeCP2 is greatly reduced in Sp1-/- embryos. MeCP2 is thought to be required for the maintenance of differentiated cells. We suggest that Sp1 is an important regulator of this process.

bcl-2 expression confers androgen independence in androgen sensitive prostatic carcinoma

Expression of the bcl-2 proto-oncogene is associated with the progression of prostate cancer to androgen-independence. Dunning R3327G (DG) cells were engineered to express high levels of bcl-2 protein. The parental DG (DG-P) cell line and bcl-2 transfectant (DG-B) clones were grown as subcutaneous tumor explants in male athymic nude mice. The rate of tumor growth after castration was significantly lower in DG-P tumors but was unaffected in DG-B tumors. The proliferative indices (PI) in DG-P and DG-B tumors were similar, however, apoptotic indices (ApI) were significantly lower in DG-B tumors before castration. Following castration the PI and ApI decreased significantly in DG-P but not DG-B tumors. Bax upregulation was not observed in the DG-P or DG-B tumors, but did occur in the ventral prostate, after castration. These findings support a role for bcl-2 expression in conferring androgen-independent growth during prostate cancer progression.

Continuous versus cyclic parenteral nutrition during bonemarrow transplantation: assessment and follow-up

The aim of this prospective, randomized clinical trial was to compare the efficacy of parenteral nutrition (PN) in adult bone marrow transplant (BMT) patients on a continuous (CON) versus a cyclic (CYC) regimen. Twelve patients received CON PN and 12 CYC PN. The groups were homogeneous. CON PN received 27.2 +/- 3.7 kcal/kg/day and for CYC PN 25.9 +/- 4.2 kcal/kg/day (P= 0.45). The duration of PN was 20.4 +/- 7.9 days and 27.3 +/- 13.4 days respectively (P = 0.14). There were no differences between initial and final body weights, either within or between groups. The initial pre-albumin levels were 16.1 +/- 7.5 mg/dl and 20.1 +/- 4.9 mg/dl in CON PN and CYC PN, respectively (P= 0.22), and these were maintained throughout the study. Blood glucose levels did not differ between groups. Measures of liver function were moderately increased, but with no significant differences between groups. There were no significant differences regarding the efficacy of PN or the appearance of complications between CON PN and CYC PN in patients with BMT.

Analysis of the individual contributions of immunoglobulin heavy and light chains to the binding of antigen using cell transfection and plasmon resonance analysis

We have cloned the Tg10 murine monoclonal antibody, which is specific for a human thyroglobulin (hTg) epitope targeted by autoantibodies in several thyroid pathologies. Transfection of COS-7 cells with plasmids expressing Tg10H and -kappa chains combined with surface plasmon resonance analysis (BIAcore) of culture supernatants showed that the entire cloned Tg10 antibody displays an affinity comparable to that of the parental antibody. This approach also permitted determination of the probable role of each chain to the recognition of the cognate epitope due to the ability of COS-7 cells to secrete independently each of the two constituting immunoglobulin chains. Tg10 heavy chain recognizes hTg in the absence of the light chain, but with a ten-fold lower affinity mainly due to an increase in kappaoff. In contrast, the light chain is unable to bind hTg on its own. This suggests that the latter is probably involved in stabilization rather than in initiating the formation of the antibody/antigen complex and that the specificity of Tg10 is mostly, if not exclusively, carried by the heavy chain. The potential applications of combined cell transfection and surface plasmon resonance to our understanding of antigen/antibody interactions are discussed.

Targeted infection of human cells via major histocompatibility complex class I molecules by Moloney murine leukemia virus-derived viruses displaying single-chain antibody fragment-envelope fusion proteins

As an approach to cell targeting by retroviruses, the lack of which constitutes one major limitation of retroviral vector technology, we engineered the Moloney murine leukemia virus ecotropic envelope glycoprotein. When inserted between amino acids 6 and 7 of the latter, a single-chain antibody fragment (ScFv) specific for human major histocompatibility complex class I molecules was shown to be able to redefine the tropism of ecotropic Moloney murine leukemia virus-derived retroviral particles by allowing infection of major histocompatibility complex class I-positive human cells. At variance with other recently described experimental systems, the type of modification adopted here allowed targeted infection in the absence of coexpressed wild-type env-encoded protein molecules. Interestingly, the chimeric ScFv-env protein also retained the ability to recognize the ecotropic receptor and allowed infection of murine cells, albeit at a reduced efficiency.

Androgen biosynthesis and secretion in developing Xenopus laevis

In the frog, Xenopus laevis, castration or anti-androgen treatment during late tadpole or early juvenile stages blocks masculinization of vocal neuroeffectors in males while exogenous androgen or a testicular transplant masculinizes vocal neuroeffectors in females. To elucidate the relation between androgen secretion and the process of masculinization, we measured androgens by radioimmunoassay in adults, juveniles, and tadpoles. In adult females, values for both testosterone (T) and dihydrotestosterone (DHT) were essentially identical during the winter and the summer while in males, summer values for both androgens were 7 to 8x winter values. For DHT, circulating values in males significantly exceeded those in females in both winter and summer while for T, values differed significantly only in summer. Sex differences in circulating androgen arise at late juvenile stages (PM4 and PM5); T values are higher in males than in females and higher, for both sexes, in winter than in summer. During early juvenile stages (PM1-PM3), there were no seasonal or sex differences in circulating androgens. While androgens were detected in liver during late tadpole stages (stage 56-66), no sex differences were apparent. Androgens can be detected in tadpole tissues, as early as tadpole stage 47. delta 5-3 beta-Hydroxysteroid dehydrogenase (HSD) histochemistry indicates that tadpole gonads and interrenals (and, to a much lesser extent, kidneys) are the only tissues capable of steroid biosynthesis. Interrenal HSD activity was present throughout tadpole development; in gonads, activity began before sexual differentiation. Thin-layer chromatographic separation of steroid metabolites following in vitro incubation with radioactive precursors indicated that the interrenals were more active than the gonads in tadpoles but not in juveniles. Thus, interrenals and gonads of developing X. laevis can synthesize delta 4 steroids (which include androgens) and, from early tadpole stages, are capable of metabolizing pregnenolone and testosterone, early and late compounds in the steroid synthetic pathway, respectively. The absence of dramatic sex differences in T or DHT levels during late tadpole and early juvenile stages suggests that while necessary, androgen secretion is not sufficient for masculinization of vocal neuroeffectors.

Cloning and expression of a single-chain antibody fragment specific for a monomorphic determinant of class I molecules of the human major histocompatibility complex

B9.12.1 is a monoclonal antibody specific for a monomorphic determinant of human MHC class I molecules. It is currently used for cell typing and is useful for targeting infection of human cells by murine ecotropic retroviruses. We have cloned and expressed it in the form of a single-chain variable fragment (ScFv) that recognizes the same epitope as the parental antibody. Through genetic engineering, this ScFv may be used for developing new cell-typing probes and new retroviral targeting approaches.

Expression in Escherichia coli of soluble and M13 phage-displayed forms of a single-chain antibody fragment specific for digoxin: assessment in a novel drug immunoassay

A high affinity anti-digoxin single-chain Fv antibody fragment (scFv) was cloned from the mouse 2C2 hybridoma cell line and was functionally expressed both in the Escherichia coli periplasm as a soluble molecule and at the surface of the filamentous M13 bacteriophage as a fusion protein with the gene III minor coat protein. The 2C2 scFv sequence significantly differs from that of all the other anti-digoxin antibodies previously described. The 2C2 scFv shares with its parental monoclonal antibody a high specificity for digoxin, a cross-reactivity with active digoxin metabolites, but none with inactive metabolites. M13 phages displaying the 2C2 scFv at their surface have a high apparent affinity constant for digoxin (6.6 x 10(8) M-1) and were directly used to set up a novel type of immunoenzymatic assay for monitoring digoxin in sera of patients treated for either congestive heart failure or cardiac arrythmias. We thus report for the first time that phages displaying scFv may constitute a large source of important new reagents in the field of immunodiagnosis.

Reversible contractile dysfunction of viable myocardium. Implications for decision making process in post-infarction patients

Myocardial dysfunction and silent myocardial ischemia have been identified as important prognostic factors following acute myocardial infarction, also in low risk patients. In postinfarction patients, impaired left ventricular function is the result of fixed scar and reversible contractile dysfunction of viable stunning or hibernating myocardium. Post-extrasystolic potentiation (PESP) during 2-dimensional echocardiographic monitoring may be used to detect the presence of viable myocardium in asynergic myocardial segments. Incidence of reversible contractile dysfunction is a very common phenomenon at predischarge examination after myocardial infarction in asymptomatic patients, and it is independent on the persistence of silent ischemia. A progressive loss of myocardial viability occurs over the first year following the acute phase despite the maintenance of an asymptomatic clinical status. This phenomenon is associated with significant dilatation of the left ventricle. Moreover, silent ischemia is strongly related with this progressive loss of myocardial viability and left ventricular dilatation. Thus, it becomes evident that the most important role of medical and interventional approaches consists of limiting the acute necrosis by reperfusion and in preventing the loss of viable chronically hypoperfused myocardium that appears to be a major factor of left ventricular remodeling and changes over time of prognostication in individual patients. Finally, the presence of viable myocardium by PESP in the arterial zone at risk is highly predictive of 4-year mortality, particularly in patients with low ejection fraction (< 40%), and identifies patients who are suitable candidates for revascularization after myocardial infarction.

Left ventricular function and prognosis after myocardial infarction: rationale for therapeutic strategies

Prognosis after acute myocardial infarction is strongly associated with left ventricular dysfunction. However, asynergy does not necessarily imply loss of viability and myocardial necrosis. In fact, two different patterns of contractile dysfunction, possibly coexisting, have been shown after acute myocardial infarction: Stunning and hibernation represent distinct patterns of contractile dysfunction that share the character of reversibility. It is noteworthy, then, to identify the presence of these two conditions at the bedside and to develop medical treatment to effect recovery of myocardial dysfunction. This strategy has the potential to ameliorate the outcome of patients after acute myocardial infarction by improving left ventricular function. Beta-blocker therapy significantly reduces mortality and the incidence of reinfarction after an acute myocardial infarction: These benefits result from the prevention of sudden death, the reduction of the extent of myocardial injury during the acute phase, and a further antiischemic action. Nevertheless, beta-blocker therapy increases left ventricular dilatation. Recent experimental and clinical data show that ACE inhibitors confer positive therapeutic effects after myocardial infarction by reducing the extent of left ventricular dilation, by reducing mortality, and by improving the clinical outcome. Not all patients, however, can be subjected to this therapeutical approach because of the possible detrimental effects produced by hypotension and by block of neurohormonal activation, sometimes truly compensatory in the early phase. Therefore, it would be interesting to suggest a combination therapy of a beta-blocker with a vasodilator agent (ACE inhibitor or calcium-channel blocker.

Effects of omeprazole on ethanol metabolism: an in vitro and in vivo rat and human study

Since some H2-receptor antagonists, like cimetidine or ranitidine, affect ethanol metabolism by interference with gastric and/or hepatic alcohol dehydrogenase (ADH) it was investigated whether omeprazole has a similar effect and its effects were compared with those of cimetidine, an inhibitor of gastric ADH. The first-pass metabolism (FPM), quantified by measuring the difference between areas under the curve (AUC) of ethanol blood concentrations after oral intake or intravenous administration of the same amount (0.3 g kg-1 b.w.) of ethanol (EtOH), was studied before and after 1 week of omeprazole (20 mg daily) or cimetidine (800 mg daily) administration in 10 normal male volunteers. ADH activity was determined in gastric mucosal samples, collected during endoscopy, before and after 1 month of omeprazole treatment. The effect of the drugs on gastric and hepatic ADHs was studied in vitro in both rat and man. No significant effect of omeprazole was found on AUCs of the blood EtOH concentrations. The ADH activity in antral mucosa before and after omeprazole therapy did not show significant differences. In vitro, omeprazole reduced the activity of the low Km gastric ADH with a Ki of 5.6 mM in rat and the hepatic ADH activity with a Ki of 2.4 mM in man, whereas the drug did not show any effect on hepatic ADH in rat and gastric ADH in man. On the contrary, cimetidine increased the AUCs of EtOH blood concentrations after both gastric and intravenous route and, in the in vitro assay, inhibited gastric and hepatic ADH in both man and rat. These results indicate that omeprazole does not affect EtOH metabolism in man and seems to be safer than cimetidine in subjects unable to reduce ethanol intake during the therapy for peptic ulcer or other hypersecretory conditions.

Replicon typing characterization of plasmids encoding resistance to gentamicin and apramycin in Escherichia coli and Salmonella typhimurium isolated from human and animal sources in Belgium

Escherichia coli and salmonella strains with plasmids conferring resistance to gentamicin and apramycin have been isolated with increasing frequency both from cattle and hospital patients in Belgium. The apramycin-gentamicin resistance plasmids were characterized in recipient strains by their profiles and molecular weights using agarose gel electrophoresis, by their antimicrobial resistance patterns and by replicon typing using a series of DNA probes specific for the genes controlling their systems of replication. Overall, most of the plasmids differed in their DNA electrophoretic patterns. Seventeen different antimicrobial resistance profiles were observed, and there were six different types of replicons. However, two replication genes predominated and had a preferential distribution in different bacterial species. The rep FIC.a plus rep Q multireplicon was found mainly in plasmids recovered from gentamicin- and apramycin-resistant E. coli while replicon of the type rep FIC.b largely prevailed in S. typhimurium. Identical replication genes were found in most animal and human strains, hence suggesting a high homology between apramycin-gentamicin plasmids in these communities. Finally, our results indicate that the rapid spread of apramycin-gentamicin-resistance in several species of Enterobacteriaceae isolated from animals and from humans in Belgium is not due to a single plasmid, but rather that the gene encoding AAC(3)-IV is carried by various replicons.

Borreliosis risk after tick bite in north-eastern Italy

Lyme Borreliosis is an infectious disease caused by the Borrelia burgdorferi spirochete transmitted to man by a tick bite. The aim of this study was to assess the predictive value of tick bites for the diagnosis of Borreliosis in a sample of 266 subjects residing in an endemic area of north-eastern Italy. In the serological diagnosis of Borreliosis, positive and negative predictive values of tick bites were found to be 24% and 88% respectively.

[The Pordenone study on the precursors of atherosclosis in childhood. A 10-year follow-up. Cigarette smoking]

We have studied smoking habit in the sample enrolled in the ten year follow-up of the "Pordenone Study on the Precursors of Atherosclerosis in Childhood". The response rate at ten year follow-up was very high (about 90%). Prevalence of smoking is 45.1% among males and 25.6% among females. Males and females aged 23 present a prevalence of smokers higher than the other groups while the group aged 26 smoke less. Males began to smoke at 16.4 years, females at 16.7. Mean daily consumption is 12.6 cigarettes among males, and 5.0 among females. Juvenile experimentation with cigarettes and juvenile smoking habit are strong predictors to smoke ten years later; while parental smoking behaviour is not so influential. Therefore we conclude that smoking habit acquired in youngs has a high probability to be maintained in adults, remarking the importance of planning a preventive intervention as early as possible.

High genetic homology between plasmids of human and animal origins conferring resistance to the aminoglycosides gentamicin and apramycin

Escherichia coli and Salmonella strains resistant to gentamicin and apramycin were isolated from cattle in France and Belgium and from patients in hospitals. Homology between plasmids of both human and animal origins encoding aminoglycoside 3-N-acetyltransferase was revealed by digestion with several restriction endonucleases and confirmed by hybridization with different replicon-specific probes.

[Meningococcal meningitis in Spain (1878-1987). VI. Evolution of the proteic subtypes within the serotypes 2 and 15 of Neisseria meningitidis during the epidemic wave]

We have serotyped 620 strains of Neisseria meningitidis, isolated from patients between 1978-1987. These strains, belonging to serotypes 2 and 15, were the most prevalent ones detected during the last epidemic outbreak in Spain. These strains were analyzed by means of polyacrylamide gel electro-phoresis and monoclonal antibody coagglutination, to differentiate subtypes into type 15 and type 2 complex (2a, 2b and 2c types). The proportion of type 2b strains is quite high in group B, and the proportion of subtypes P1.15 and P1.16 is very similar in the same serogroup. We compared the results with those obtained in other countries in our geographical area.

[Cases of serous otitis admitted to the ENT Department of the V. Babeş Hospital over the last 7 years]

A total number of 283 patients with serious otitis were admitted during the latter 7 years. In more than 98% of cases the auditory function was integrally recovered to values prior to the disease following the treatment of tubal dysfunction and serious otitis. In case of complete irreversible block at the level of the tributary ototubal lymph nodes perforation of the ear drum and otomastoid superinfections may occur. Stress is laid on the importance of a correct diagnosis and timely intervention before severe alteration of the auditory function.

Megakaryocytic development in liquid cultures of cryopreserved leukocyte stem cell concentrates from chronic myelogenous leukemia patients

The proliferation and differentiation of human megakaryocytes in liquid culture has been obtained using cryopreserved light-density blood cell concentrates from chronic myelogenous leukemia (CML) patients. A large number of megakaryocytes, representing 20%-60% of total cells cultured, developed after 12-14 days in liquid cultures supplemented with human plasma, while fetal calf serum supported the development of cells of the megakaryocytic lineage poorly. Ploidy studies showed the presence of 8N and 16N cells in human plasma-supplemented cultures while very few cells with DNA content greater than 4N were found in those supplemented with fetal calf serum. Using the FACS IV cytofluorometer, 1-2 X 10(6) megakaryocytes/h were sorted after immunolabeling of the human plasma-cultured cells with a monoclonal antibody reacting against the platelet glycoprotein complex IIb-IIIa. Thus, cryopreserved CML blood stem cell concentrates seem to offer a reproducible source of human megakaryocytes that retain their capacity to proliferate and differentiate in liquid cultures. These megakaryocytes can be used for the study of platelet glycoprotein biosynthesis as well as the regulation of megakaryocytopoiesis.

In vitro transcription initiation from three different Escherichia coli promoters. Effect of supercoiling

Transcription initiation from beta-lactamase, tetracycline resistance and RNA 1 promoters, present in plasmid pAT153, were studied employing the abortive initiation technique. Assays appear to be promoter-specific with supercoiled and linear templates. Supercoiling enhances the isomerization rate constant of the open RNA-polymerase--promoter complex formation. Results agree with the in vivo behaviour of the corresponding promoters, and allow us to propose a hypothesis about the effect of supercoiling on transcription initiation.

High performance liquid chromatographic analysis of molecular species of phosphatidylcholine--development of quantitative assay and its application to human bile

In this paper we propose a novel, rapid and simple high-performance liquid chromatographic (HPLC) method for the identification and quantitation of individual phosphatidylcholine (PC) molecular species from natural mixtures. To overcome difficulties deriving from the lack of adequate standards and from the variability of the responses to UV spectrophotometric detectors currently used in HPLC analysis, we first fractionated and quantitated the major molecular species of a commercial egg PC by means of a preparative column. The identification of PC molecular species was confirmed by gas-liquid chromatographic analysis of fatty acids. We employed the fractions recovered from preparative HPLC to determine the detector calibration factors of the individual molecular species separated using an analytical, high-speed, reversed-phase HPLC column. The proposed method seems to be adequate for the analysis of PC from many biological sources. Its application to the analysis of human hepatic and gallbladder biliary PC is shown.

Regeneration of rat tracheal epithelium: changes in gap junctions during specific phases of the cell cycle

Uninjured mitotically inactive tracheal epithelium has virtually no gap junctions. When the epithelium is stimulated to proliferate synchronously through a single wave of DNA synthesis and cell division, study of thin sections and freeze-fracture replicas by conventional transmission electron microscopy reveals that gap junctions are formed by the end of the DNA synthetic (S) phase. During the period of mitosis (M), the gap junctions disappear and are not again observed as the superficial cells undergo mucous and ciliary differentiation and normal pseudostratified architecture is restored. If the regenerative cells are continuously stimulated so they go through at least one additional S phase, gap junctions begin to reappear in G1 and reach peak numbers at the end of the second S phase. The correlation of the appearance of gap junctions in regenerating tracheal epithelium with a specific phase of the cell cycle and the absence of these junctions in cells in other phases of the cycle and in the differentiated progeny cells suggests that this surface feature plays a role in control of mitotic activity.