Collagen-cliondroitin-6-sulfate hydrogel implants in CNS lesion cavities favor glial repair, the differentiation of co-implanted neurons and the growth of axons

Collagen chondroitin-6-sulfate hydrogels containing embryonic striatal neurons were implanted into premade brain cavities of the rat striatum. The bioimplant was progressively transformed into a new matrix mostly by the deposition of newly formed collagen and by the ingrowth of glial cells and glial cell processes. At two months, the new matrix has partly restructured the lesion cavity. Cells co-implanted with the hydrogels attached, survived and differentiated while nerve fibers of the host striatum grew into the biomatrix.

Laboratory and clinical outcomes of pharmacogenetic vs. clinical protocols for warfarin initiation in orthopedic patients

BACKGROUND

Warfarin is commonly prescribed for prophylaxis and treatment of thromboembolism after orthopedic surgery. During warfarin initiation, out-of-range International Normalized Ratio (INR) values and adverse events are common.

METHODS

In orthopedic patients beginning warfarin therapy, we developed and prospectively validated pharmacogenetic and clinical dose refinement algorithms to revise the estimated therapeutic dose after 4 days of therapy.

RESULTS

The pharmacogenetic algorithm used the cytochrome P450 (CYP) 2C9 genotype, smoking status, peri-operative blood loss, liver disease, INR values and dose history to predict the therapeutic dose. The R(2) was 82% in a derivation cohort (n = 86) and 70% when used prospectively (n = 146). The R(2) of the clinical algorithm that used INR values and dose history to predict the therapeutic dose was 57% in a derivation cohort (n = 178) and 48% in a prospective validation cohort (n = 146). In 1 month of prospective follow-up, the percent time spent in the therapeutic range was 7% higher (95% CI: 2.7-11.7) in the pharmacogenetic cohort. The risk of a laboratory or clinical adverse event was also significantly reduced in the pharmacogenetic cohort (Hazard Ratio 0.54; 95% CI: 0.30-0.97).

CONCLUSIONS

Warfarin dose adjustments that incorporate genotype and clinical variables available after four warfarin doses are accurate. In this non-randomized, prospective study, pharmacogenetic dose refinements were associated with more time spent in the therapeutic range and fewer laboratory or clinical adverse events. To facilitate gene-guided warfarin dosing we created a non-profit website, http://www.WarfarinDosing.org.

Synthesis of CeO2@SiO2 core–shell nanoparticles by water-in-oil microemulsion. Preparation of functional thin film

Synthesis of nanoparticles under restricted environment offered by water-in-oil (W/O) microemulsions provides excellent control over particle size and shape, and inter-particle spacing. Such an environment has been involved to synthesize silica nanoparticles with a CeO2 core, so-called CeO2@SiO2. Aqueous fluids made up of ceria nanoparticles with a size close to 5 nm have been used as the water phase component. The starting CeO2 sols and obtained CeO2@SiO2 nanoparticles have been characterized by dynamic light scattering (DLS), X-ray diffraction, scanning and transmission electron microscopy, and specific surface area measurements. The microemulsion process has been characterized by DLS. Preliminary results on CeO2@SiO2 thin films are presented.

Safety of plasma-based sterilization: surface modifications of polymeric medical devices induced by Sterrad and Plazlyte processes

Plasma-based sterilization is a promising alternative to the use of pure ethylene oxide (EO), for low-temperature clinical sterilization of medical instruments and devices. However, few studies have been published that evaluate its safety in terms of possible damage to materials, particularly polymers. The objective of this work was to evaluate polymer surface modifications induced by commercial plasma-based sterilizers, in comparison with pure EO: Samples from 5 polymer-based devices were subjected to 1, 5, and 10 sterilization cycles by Sterrad-100, Plazlyte, and pure EO. Surface analysis was carried out by X-ray photoelectron spectroscopy (XPS), dynamic contact angle measurements (DCA), and scanning electron microscopy (SEM). Surface oxidation and wettability changes were observed on all samples sterilized by plasma-based techniques, the degree of modifications depending on the sterilizer (Sterrad, Plazlyte) and the type of polymer. Drastic changes of surface appearance were also observed by SEM on PVC samples sterilized by Plazlyte and by pure EO. Possible repercussions on safety are discussed.

Sternal wound infection after heart transplantation: incidence and results with aggressive surgical treatment

BACKGROUND

Sternal wound infection remains a significant complication. We reviewed the incidence and the treatment of sternal wound infection after heart transplantation.

METHODS

Of 226 patients who had a heart transplantation, 20 (8.8%) underwent postoperative wound debridement for superficial or deep sternal wound infection. The incidence and the survival of patients with sternal wound infection were analyzed.

RESULTS

The incidence of sternal wound infection was similar among patients treated with four protocols of immunosuppressive drugs: cyclosporine and prednisone (0 of 22; 0%); cyclosporine, prednisone, and azathioprine (2 of 24; 8.3%); cyclosporine, prednisone, azathioprine, and antithymocyte globulin (15 of 139; 10.8%); and cyclosporine, prednisone, mycophenolate mofetil, and antithymocyte globulin (3 of 41; 7.3%) (p = 0.4). Six-month and 5-year survival of patients with sternal wound infection averaged 85% +/- 8% and 74% +/- 10% compared with 92% +/- 2% and 82% +/- 3% in patients without wound infection (p = 0.15). Patients with deep sternal wound infection, debridement, and reconstruction had a 5-year survival averaging 80% +/- 10%.

CONCLUSIONS

The incidence of sternal wound infection remains similar between patients treated with the triple drug therapy. Surgical debridement and reconstruction can result in long-term survival after heart transplantation.

Solving modulated structures by X-ray and electron crystallography

X-ray diffraction can be used for accurately determining not only classical, ordinary structures, but also modulated ones. For structures with weak modulations, the modulation induced satellite reflections are often hard to be observed by X-ray diffraction, but they appear clearly in electron diffraction. In these cases, X-ray diffraction will give only average structures whereas electron diffraction will yield information about the modulations. Sr(1.4)Ta(0.6)O(2.9) is a complex modulated compound with weak modulation and small modulated domains. Here we demonstrate the power of combining X-ray and electron crystallography for studying modulated structures on powders. The modulations of Sr(1.4)Ta(0.6)O(2.9) were determined from electron diffraction (SAED) and high resolution electron microscopy (HREM) images. With specially developed image processing techniques, the weak modulations were enhanced, facilitating the interpretation of HREM images in terms of atomic structure.

Predictive value of Candida colonization index in 131 patients undergoing two different cardiovascular surgical procedures

BACKGROUND

Nosocomial candidemia is an important infection because of its increasing incidence and its high fatality rate. Candidiasis involves multiple risk factors. In this work, we study the degree of Candida colonization in cardiovascular surgical patients by taking into account the number of sites colonized and the density of growth.

METHODS

Eleven (11) selected variables (age, sex, weight, diabetes, number of antibiotics, duration of antibiotics, length of hospitalization, length of stay in surgical intensive care unit, duration of surgery, temperature during surgery, and number of bypass) were considered to predict the perioperative variation of the colonization index (CI) by Candida in 131 cardiovascular surgical patients. These patients were divided into two groups: group A, coronary artery bypass grafting with extracorporeal circulation (72 patients) and group B, coronary artery bypass grafting without extracorporeal circulation (59 patients).

RESULTS

One thousand and forty-eight fungal cultures were obtained from four different body sites and 162 isolated were identified. Candida albicans accounted for 74% of the strains in group A and 97% in group B. The statistical analysis (two-way anova) shows that group A patients with an increased CI have received significantly more antibiotics than those with a stable CI (1.50+/-0.83 vs 1.08+/- 0.40, p=0.0055).

CONCLUSIONS

Epidemiological data obtained from this study show that coronary artery bypass grafting with extracorporeal circulation procedure is associated with an increase in the use of antibiotics and subsequently a higher risk a Candida colonization-infection.

Comparison of cost-effectiveness of tuberculosis screening of close contacts and foreign-born populations

Although tuberculosis (TB) screening of immigrants has been conducted for over 50 yr in many industrialized countries, its cost- effectiveness has never been evaluated. We prospectively compared the yield and cost-effectiveness of two immigrant TB screening programs, using close-contact investigation and passive case detection. Study subjects included all immigration applicants undergoing radiographic screening, already arrived immigrants requiring surveillance for inactive TB, and close contacts of active cases resident in Montreal, Quebec, Canada, who were referred from June 1996 to June 1997 to the Montreal Chest Institute (MCI), a referral center specializing in respiratory diseases. For all subjects seen, demographic data, investigations, diagnoses, and therapy were abstracted from administrative data bases and medical charts. Estimated costs of detecting and treating each prevalent active case and preventing future active cases, based on federal and provincial health reimbursement schedules, were compared with the costs for passively diagnosed cases of active TB. Over a period of 1 yr, the three programs detected 27 cases of prevalent active TB and prevented 14 future cases. As compared with passive case detection, close-contact investigation resulted in net savings of $815 for each prevalent active case detected and treated and of $2,186 for each future active case prevented. The incremental cost to treat each case of prevalent active TB was $39,409 for applicant screening and $24,225 for surveillance, and the cost of preventing each case was $33,275 for applicants and $65,126 for surveillance. Close-contact investigation was highly cost effective and resulted in net savings. Immigrant applicant screening and surveillance programs had a significant impact but were much less cost effective, in large part because of substantial operational problems.

Immediate and long-term results of valve replacement for native and prosthetic valve endocarditis

BACKGROUND

The objective of the present study was to compare current results of prosthetic valve replacement following acute infective native valve endocarditis (NVE) with that of prosthetic valve endocarditis (PVE). Prosthetic valve replacement is often necessary for acute infective endocarditis. Although valve repair and homografts have been associated with excellent outcome, homograft availability and the importance of valvular destruction often dictate prosthetic valve replacement in patients with acute bacterial endocarditis.

METHODS

A retrospective analysis of the experience with prosthetic valve replacement following acute NVE and PVE between 1988 and 1998 was performed at the Montreal Heart Institute.

RESULTS

Seventy-seven patients (57 men and 20 women, mean age 48 +/- 16 years) with acute infective endocarditis underwent valve replacement. Fifty patients had NVE and 27 had PVE. Four patients (8%) with NVE died within 30 days of operation and there were no hospital deaths in patients with PVE. Survival at 1, 5, and 7 years averaged 80% +/- 6%, 76% +/- 6%, and 76% +/- 6% for NVE and 70% +/- 9%, 59% +/- 10%, and 55% +/- 10% for PVE, respectively (p = 0.15). Reoperation-free survival at 1, 5, and 7 years averaged 80% +/- 6%, 76% +/- 6%, and 76% +/- 6% for NVE and 45% +/- 10%, 40% +/- 10%, and 36% +/- 9% for PVE (p = 0.003). Five-year survival for NVE averaged 75% +/- 9% following aortic valve replacement and 79% +/- 9% following mitral valve replacement. Five-year survival for PVE averaged 66% +/- 12% following aortic valve replacement and 43% +/- 19% following mitral valve replacement (p = 0.75). Nine patients underwent reoperation during follow-up: indications were prosthesis infection in 4 patients (3 mitral, 1 aortic), dehiscence of mitral prosthesis in 3, and dehiscence of aortic prosthesis in 2.

CONCLUSIONS

Prosthetic valve replacement for NVE resulted in good long-term patient survival with a minimal risk of reoperation compared with patients who underwent valve replacement for PVE. In patients with PVE, those who needed reoperation had recurrent endocarditis or noninfectious periprosthetic dehiscence.

Ventriculotomy and resection for left ventricular thrombus infection with Salmonella

We report the case of a patient with a left ventricular thrombus infected by Salmonella. The diagnosis was suspected from a gallium scan demonstrating an intense activity in the lower left parasternal area. A transesophageal echocardiogram confirmed a calcified left ventricular aneurysm with a mural thrombus containing pus and heterogeneous material. The patient underwent a successful left ventricular aneurysmectomy, thrombectomy and endocardial resection under cardiopulmonary bypass which brought the infection under control.

Effect of gas composition on spore mortality and etching during low-pressure plasma sterilization

The aim of this work was to investigate possible mechanisms of sterilization by low-temperature gas plasma: spore destruction by plasma is compared with etching of synthetic polymers. Bacillus subtilis spores were inoculated at the bottom of glass vials and subjected to different plasma gas compositions (O(2), O(2)/Ar, O(2)/H(2), CO(2), and O(2)/CF(4)), all known to etch polymers. O(2)/CF(4) plasma exhibited much higher efficacy than all other gases or gas mixtures tested, with a more than 5 log decrease in 7.5 min, compared with a 2 log decrease with pure oxygen. Examination by scanning electron microscopy showed that spores were significantly etched after 30 min of plasma exposure, but not completely. We speculate about their etch resistance compared with that of synthetic polymers on the basis of their morphology and complex coating structure. In contrast to so-called in-house plasma, sterilization by Sterrad(R) tended to increase the observed spores' size; chemical modification (oxidation), rather than etching, is believed to be the sterilization mechanism of Sterrad(R).

Development of the antinuclear and anticytoplasmic antibody consensus panel by the Association of Medical Laboratory Immunologists

The Association of Medical Laboratory Immunologists (AMLI) have developed a panel of antinuclear and anticytoplasmic antibody consensus sera that can be useful for enzyme immunoassay (EIA), Ouchterlony, and immunofluorescence assay methods. It was developed to assist in the evaluation of newly available EIA methods for the detection of autoantibodies. The panel of sera was evaluated in several clinical laboratories and a large number of laboratories owned by manufacturers of clinical autoantibody testing kits. The majority of sera performed well for the EIAs in both the clinical laboratories and the manufacturers' laboratories, but some samples had discrepant results. A major source of discrepancy is the current inability of the EIA results to be directly compared in a quantitative way as no standardization exists. The evaluation demonstrated lower sensitivity of detection by the Ouchterlony method. The limited evaluation of the sera with immunoblotting and Western blotting did not show good agreement with other methods. Further work must be done to standardize blotting methods prior to their use in routine clinical testing. The sera are now available to vendors and clinical laboratories for use in the detection of SS-A, SS-B, Sm, U1-RNP, Scl-70, Jo-1, double-stranded DNA, and centromere antibodies. The availability of the consensus sera will help evaluate and improve the EIA methods currently being used.

Regional patterning of reticulospinal and vestibulospinal neurons in the hindbrain of mouse and rat embryos

The dispositions and axonal trajectories of bulbospinal neurons in the pons and medulla of mouse and rat embryos is described from the earliest times these projections can be labelled retrogradely from the cervical spinal cord. Reticulospinal and vestibulospinal neurons are clustered into identifiable groups, each with a characteristic combination of spatial domain and axon trajectory. The various groups can be labelled retrogradely in a specific developmental sequence. The position of some groups shifts from medial to lateral with development, apparently through cell migration. These observations show that the basic regional organization of the reticulospinal and vestibulospinal projections is similar in mouse and rat and is already established during early stages of axon outgrowth.

Cost-effectiveness of screening compared to case-finding approaches to tuberculosis in long-term care facilities for the elderly

BACKGROUND

To determine if the more interventionist approach of screening with the tuberculin test and chemoprophylaxis for high-risk positive reactors to control tuberculosis in long-term care facilities is cost-effective when compared to the case-finding and treatment approach.

METHOD

A decision-analysis model was designed wherein systematic screening with the tuberculin skin test of all elderly patients newly admitted to facilities was compared to public health interventions restricted to investigation of cases and contacts with symptoms of tuberculosis after suspected exposure. Differences in life-years (LY), quality-adjusted life-years (QALY), cost per QALY and LY gained, annual cost per 1000 institutional patients were calculated in a health-care system perspective.

RESULTS

In every situation analysed, screening and chemoprophylaxis were more effective. The cost per LY gained was within an acceptable range: $3437 per LY with a 0.6% nosocomial transmission rate and $7552 per LY when no nosocomial transmission was postulated.

CONCLUSION

Screening plus chemoprophylaxis for high-risk reactors is more cost-effective than case-finding. This holds even when nosocomial transmission is assumed not to occur in facilities.

Cytotoxicity and macrophage cytokine release induced by ceramic and polyethylene particles in vitro

Although the response of macrophages to polyethylene debris has been widely studied, it has never been compared with the cellular response to ceramic debris. Our aim was to investigate the cytotoxicity of ceramic particles (Al2O3 and ZrO2) and to analyse their ability to stimulate the release of inflammatory mediators compared with that of high-density polyethylene particles (HDP). We analysed the effects of particle size, concentration and composition using an in vitro model. The J774 mouse macrophage cell line was exposed to commercial particles in the phagocytosable range (up to 4.5 microns). Al2O3 was compared with ZrO2 at 0.6 micron and with HDP at 4.5 microns. Cytotoxicity tests were performed using flow cytometry and macrophage cytokine release was measured by ELISA. Cell mortality increased with the size and concentration of Al2O3 particles. When comparing Al2O3 and ZrO2 at 0.6 micron, we did not detect any significant difference at the concentrations analysed (up to 2500 particles per macrophage), and mortality remained very low (less than 10%). Release of TNF-alpha also increased with the size and concentration of Al2O3 particles, reaching 195% of control (165 pg/ml v 84 pg/ml) at 2.4 microns and 350 particles per cell (p < 0.05). Release of TNF-alpha was higher with HDP than with Al2O3 particles at 4.5 microns. However, we did not detect any significant difference in the release of TNF-alpha between Al2O3 and ZrO2 at 0.6 micron (p > 0.05). We saw no evidence of release of interleukin-1 alpha or interleukin-1 beta after exposure to ceramic or HDP particles.

Cytotoxicity and macrophage cytokine release induced by ceramic and polyethylene particles in vitro

Although the response of macrophages to polyethylene debris has been widely studied, it has never been compared with the cellular response to ceramic debris. Our aim was to investigate the cytotoxicity of ceramic particles (Al2O3 and ZrO2) and to analyse their ability to stimulate the release of inflammatory mediators compared with that of high-density polyethylene particles (HDP). We analysed the effects of particle size, concentration and composition using an in vitro model. The J774 mouse macrophage cell line was exposed to commercial particles in the phagocytosable range (up to 4.5 μm). Al2O3 was compared with ZrO2 at 0.6 μm and with HDP at 4.5 μm. Cytotoxicity tests were performed using flow cytometry and macrophage cytokine release was measured by ELISA.

Cell mortality increased with the size and concentration of Al2O3 particles. When comparing Al2O3 and ZrO2 at 0.6 μm, we did not detect any significant difference at the concentrations analysed (up to 2500 particles per macrophage), and mortality remained very low (less than 10%). Release of TNF-α also increased with the size and concentration of Al2O3 particles, reaching 195% of control (165 pg/ml v 84 pg/ml) at 2.4 μm and 350 particles per cell (p < 0.05). Release of TNF-α was higher with HDP than with Al2O3 particles at 4.5 μm. However, we did not detect any significant difference in the release of TNF-α between Al2O3 and ZrO2 at 0.6 μm (p > 0.05). We saw no evidence of release of interleukin-1α or interleukin-1ß after exposure to ceramic or HDP particles.

Induction of macrophage apoptosis by ceramic and polyethylene particles in vitro

The purpose of this study was to investigate in vitro the presence of apoptotic cell death after macrophage stimulation with different ceramic (Al2O3 and ZrO2) and high density polyethylene (HDP) particles. We also analyzed the effects of particle size, concentration, and composition. The J774 mouse macrophage cell line was exposed to commercial particles of different sizes (up to 4.5 microm) and concentrations (up to 500 particles per macrophage). Fluorescence microscopy and DNA laddering were used to investigate the presence of apoptosis in cell cultures after 24 h of incubation. Fluorescence microscopy of propidium iodide stained cells showed two characteristic morphological features that occur in apoptotic cells, namely nuclear condensation and heterogeneity of stain uptake. The effect of ceramic particles on apoptotic nuclear morphology was size- and concentration-dependent and reached a plateau above 150 particles per macrophage at 1.3 microm. With regards to composition, we did not find any difference in cell morphology between Al2O3 and ZrO2. Ceramic and HDP particles induced DNA fragmentation into oligonucleosomes as evidenced by DNA laddering, another characteristic of apoptosis. The induction of DNA laddering was size- and concentration-dependent whereas particle composition (Al2O3 vs. ZrO2 and Al2O3 vs. HDP) had no effect. In conclusion, our results demonstrated that ceramic and HDP particles induce macrophage apoptotic cell death in vitro and open doors for possible modulation of debris-induced periprosthetic osteolysis.

Simultaneous flow cytometric measurement of Streptococcus suis phagocytosis by polymorphonuclear and mononuclear blood leukocytes

A simple flow cytometric method was used to study simultaneously the phagocytosis of Streptococcus suis serotype 2 by polymorphonuclear and mononuclear blood leukocytes from swine and humans. Using this method with a bacteria-to-leukocytes ratio of 10:1 and after 60 min of incubation, 80.2 +/- 2.8% of swine granulocytes and 77.0 +/- 2.8% of swine monocytes were shown to contain FITC-labelled S. suis serotype 2 strain 735. Using the same strain, FITC-labelled bacteria were found in 95.5 +/- 3.2% of human granulocytes and in 92.8 +/- 3.6% of human monocytes. The phagocytosis rates of avirulent and virulent strains of S. suis were not significantly different.

Flow cytometric analysis of macrophage response to ceramic and polyethylene particles: effects of size, concentration, and composition

Using the J774 macrophage cell line, we designed an in vitro model to analyze by flow cytometry the effects of size, concentration, and composition of ceramic (Al2O3 and ZrO2) and high density polyethylene (HDP) particles on phagocytosis and cell mortality. Inflammatory mediator (TNF-alpha) also was measured by ELISA. Kinetic studies revealed that phagocytosis of the particles begins very early after cell exposure, increasing with time and particle concentration and reaching a plateau after 15 h. This implies that the optimum period to evaluate cellular response to particulate debris is between 15 and 24 h of incubation. Results also showed that phagocytosis increases with concentration for particles up to 2 microns. For larger particles (up to 4.5 microns), phagocytosis seems to reach a plateau independent of size and concentration, which suggests a saturation of phagocytosis that is most likely dependent on overall particle volume ingested. We did not detect any significant difference in phagocytosis between Al2O3 and ZrO2 at 0.6 microns. Al2O3 seems to be more easily phagocytosed than HDP at the same size (4.5 microns) and concentrations. Cytotoxicity studies revealed that macrophage mortality increases with particle size and concentration for sizes greater than 2 microns. Smaller particles (0.6 microns) cause cell mortality only at higher concentrations (from 1,250 particles per cell), but the mortality is still very low (10%). No significant difference in cell mortality and TNF-alpha release was found between Al2O3 and ZrO2. Effects of Al2O3 and HDP at 4.5 microns were compared by measuring TNF-alpha release. Results showed that TNF-alpha release increases with particle concentrations and is higher with HDP than with Al2O3.

Effects of interferon gamma on growth, apoptosis, and MHC class II expression of immature rat intestinal crypt (IEC-6) cells

Intestinal epithelial cells and the mucosal immune cells in close proximity are thought to interact very closely. One well-established mechanism of this intercellular cross-talk is via the production of cytokines such as interferon gamma (IFNgamma). The aim of this study was to analyze the effects of IFNgamma on intestinal crypt epithelial cells. IEC-6 cells were cultured in the presence or absence of IFNgamma to measure its effects on proliferation, cell cycle, apoptosis, and major histocompatibility complex (MHC) class II antigen expression. Even at very low doses (0.01 U/ml), IFNgamma significantly inhibited IEC-6 cell proliferation, as demonstrated by reduced 3H-thymidine uptake, stable cell count, and complete arrest in the quiescent G0/G1 phase of the cell cycle. Incubation with supraphysiological doses of IFNgamma (100-1,000 U/ml) did not induce apoptosis, as assessed by morphology and the TUNEL assay. IFNgamma significantly induced de novo IEC-6 class II antigen expression. Tumor necrosis factor alpha (TNF alpha), which alone had no effect, synergistically enhanced this effect of IFNgamma. MHC class II antigen expression was observed to be independent of cell cycle phase. Our results indicate that IFNgamma alters immature crypt epithelial cell turnover and upregulates MHC class II expression. These alterations may be important in the pathogenesis of immune-mediated bowel disorders.

Calcium-binding proteins in primate cerebellum

Single and double antigen localization procedures were used to study the distribution of the calcium-binding proteins calretinin, calbindin and parvalbumin in the cerebellum of the squirrel monkey (Saimiri sciureus). The immunostaining experiments have revealed that each of the three calcium-binding proteins occurred, either alone or in various combinations, in many neuronal types of the monkey cerebellum, including the Purkinje cells. Immunoreactivity for calbindin was detected in virtually all Purkinje cells, whereas immunoreactivity for calretinin and parvalbumin was encountered only in some subpopulations of Purkinje cells. In the vermal region, parvalbumin immunostaining appeared in the form of typical weak and strong alternating parasagittal bands. Calretinin immunoreactivity was found in virtually all neurons and fiber systems related to the granular layer, including the monodendritic cells, the granule cells and their parallel fibers, the Golgi and Lugaro cells and the mossy fibers. The Golgi cells also displayed calbindin and parvalbumin immunoreactivity. Parvalbumin was found to labeled both the climbing and mossy fibers, as well as the basket and stellate cells lying in the molecular layer. These results reveal that virtually all the different neuronal types in the primate cerebellum contain at least one of three calcium-binding proteins investigated in the present study. Furthermore, calretinin appears to be a particularly reliable molecular maker for all the neuronal elements associated with the granular layer in the primate cerebellum.

Epidemiological study of Candida spp. colonization in cardiovascular surgical patients

Candida infections involve multiple risk factors. Among the independent risk factors identified, the degree of colonization of Candida spp. allows the prediction of subsequent severe candidosis in surgical patients. The aim of this study was to assess among 13 selected variables, those that would best predict the perioperative variation of the colonization index (CI) of Candida spp. in cardiovascular surgical patients. The colonization index took into account the number of sites colonized and the density of growth. The results showed that 56.8% of our patients were colonized perioperatively. A total of 116 isolates were identified and Candida albicans accounted for 76.7% of the strains. Among the patients who developed post-surgical Candida infections, 57.1% had an increase of the CI early after the operation. By univariate analysis, three factors were significantly associated with an increase of the CI in patients after surgery; sex (female), the duration of central intravascular catheterization and the length of stay in the surgical intensive care unit (SICU). Epidemiological data could help predict those patients who are at risk of developing Candida infections.

The early neuronal organization predicts the path followed by some major axonal bundles in the embryonic brainstem

In the embryonic CNS, preformed pathways precede the growth of axonal fasciculi [Katz M. J. and Lasek R. J. (1980) Cell Motil. 1, 141-157; Katz M. J. et al. (1980) Neuroscience 5, 821-833]. What are the developmental events that lead to the elaboration of these preformed pathways? To answer this question, we investigated the organization of the primitive neural tube and more particularly the arrangement of the early-generated cells using [3H]thymidine autoradiography or bromodeoxyuridine. Our data suggest that the position of early-generated cells might be involved in the setting of such pathways. In the brain stem of E12(0) (12 days and 0 h) and E12(15) rat embryos, the first-generated cells were organized into three longitudinal columns associated with glycoconjugate-rich extracellular spaces in the adjacent primitive marginal layer. Also, axons traced with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) were contiguous to the early-generated cellular columns and represented the primordium of the medial longitudinal fasciculus, the lateral longitudinal tract and the mesencephalic trigeminal tract. Our results show a correlation between the organization of early-generated cells, likely neurons, and the pattern of extracellular spaces in the marginal layer where axons grow. It has been reported in the literature that neurons produce elements of the extracellular matrix such as growth-modulating molecules or space-creating molecules. We therefore suggest that the position of early-generated neurons could be involved in the elaboration of a template for the setting of some major longitudinal tracts during embryonic development of the brainstem.

Cardioprotective effects of diltiazem during acute rejection on heterotopic heart transplants

In the presence of severe rejection, cardiac allograft perfusion has been shown to be impaired. Since a functionally reversible vasoconstrictor component has been identified in this condition and rejection does not reverse if ischemia does not, we hypothesized that diltiazem may be beneficial in this condition. Experiments were performed on dogs with heterotopic heart transplants and chronic instrumentation for the assessment of allograft perfusion. Two groups of cardiac allograft recipients were studied: untreated recipients and recipients treated with the calcium antagonist diltiazem (180 mg twice daily, orally). Allograft blood flow was monitored daily along with plasma diltiazem levels. The lymphoproliferative response to mitogens was studied at selected intervals until terminal rejection. Contractile function of the graft was assessed daily by palpation. Without immunosuppression, terminal rejection was observed within 7 days. Rejection was confirmed by histology; cellular infiltration and myocyte necrosis were present in all cardiac allografts but to a significantly lesser degree in diltiazem-treated recipients. The mean blood flow of heterotopically implanted hearts was in the range of 35-50 ml/min, which decreased steadily in untreated recipients. In contrast, significant improvement of allograft perfusion was observed in diltiazem-treated recipients at days 4-6 after transplantation. Diltiazem also significantly attenuated mitogen-induced lymphocyte proliferation at peak sensitivity (2 days after transplantation). Diltiazem plasma concentrations were in the therapeutic range (30-60 ng/ml) before and after cardiac transplantation. Results of the present study demonstrate beneficial effects of diltiazem in the course of severe cardiac rejection. Such findings support its use during rejection when maintenance of graft blood flow and myocyte protection may be important for myocardial function and viability.

Synthèse et caractérisation structurale d'un phosphate d'indium In3P2O8 présentant des paires In–In

The crystal structure of the new indium phosphate In3P2O8 has been determined from single-crystal data. The unit cell is cubic [space group I{\bar 4}3d (Z = 8)] with a = 11.152 (1) Å. The structure is characterized by a three-dimensional arrangement of isolated PO4 3− tetrahedra forming the anionic network, while the electroneutrality is insured by (In—In)4+ cationic pairs. The In—In distance, equal to 2.630 (1) Å, is the shortest In—In bond ever found. Powdered In3P2O8 can be synthesized from a mixture of 4 InPO4:1 In2O3 after thermal reduction under H2.

Rhombomere-specific origin of branchial and visceral motoneurons of the facial nerve in the rat embryo

The goal of this study was to localize selectively the facial nerve branchial and visceral motoneurons in the rat embryo hindbrain. This was achieved by injecting dextran amines into the peripheral facial nerve on embryos maintained in an artificial cerebrospinal fluid. Sprague-Dawley rat embryos 13, 14, and 15 days old (E13, E14, E15) were obtained by cesarean section. Branchial motoneurons were first labeled at E13. They were close to the midline and migrated from rhombomere (r) 4 toward r5 and r6. By E15, they had migrated caudally and ventrolaterally into the former location of r6. Most of them had reached their "adult" position by E15. Another group of motoneurons, the accessory facial nucleus, was found in r4 at E13 and in corresponding regions at later stages. Visceral motoneurons were labeled from the periphery at all stages. At E13, they were mainly in r5 but also in r2, r3, r4, and r6. At E14, most of them had migrated laterally, and, by E15, they were in the prospective parvocellular reticular formation. They could be divided into two subgroups: a more rostral one with fibers that made loops close to the midline and a more caudal one with fibers that went directly to the exit. The findings presented here show that most branchial and visceral motoneurons of the facial nerve are born in different and specific rhombomeres. Interestingly, developmental genes are expressed specifically in these rhombomeres and could be involved in the genesis of the facial and superior salivatory nuclei.

[Profile of biostatistics utilization in three medical reviews. Implications for medical education]

OBJECTIVE

To identify the most commonly used biostatistical concepts and tests in three journals read by family physicians.

DESIGN

Descriptive study of the biostatistical content of 12 issues of the Canadian Medical Association Journal (CMAJ), Canadian Family Physician (CFP), and the New England Journal of Medicine (NEJM).

MAIN OUTCOME MEASURES

Frequency of citations of concepts and tests, and Spearman's correlation coefficients comparing the biostatistical profiles of the three journals.

RESULTS

Biostatistical content of NEJM was diverse (on average, 39 concepts and 21 tests per issue). In CFP, we found 10 concepts and four tests per issue. In CMAJ, there were, on average, nine concepts and five tests per issue.

CONCLUSIONS

The journals' profiles (order of importance of concepts and tests) were fairly similar.

Tumor necrosis factor-alpha inhibits lipid and lipoprotein transport by Caco-2 cells

Cytokines, important mediators of inflammation, have been shown to cause disturbances in circulating and hepatic lipid metabolism. Although the intestine plays a major role in dietary fat transport and largely contributes to plasma lipoproteins, the effects of cytokines on intestinal lipid handling remain unknown. In the present study, the modulation of lipid, apoprotein, and lipoprotein synthesis and secretion by tumor necrosis factor-alpha (TNF-alpha) was investigated in Caco-2 cells. Highly differentiated and polarized cells (20 days in culture) were incubated for 20 h with recombinant human TNF-alpha (100-500 ng/ml). No cytotoxic effect of TNF-alpha cells was observed, as indicated by the determinations of Caco-2 cell viability and monolayer transepithelial resistance. Moreover, no differences in cell maturation (sucrase activity) or cell proliferation ([3H]thymidine incorporation and cell cycle analysis) were detected between treated and control cultures. Significant inhibition of lipid secretion by TNF-alpha was observed, with the greatest reduction at 500 ng/ml. TNF-alpha significantly decreased Caco-2 cell secretion of phospholipids (22%), triglycerides (30%), and cholesteryl ester (37%). It also significantly diminished the export of newly synthesized low-density lipoproteins (LDL; 20%) and high-density lipoproteins (HDL; 13%), with a lesser effect on very low-density lipoproteins (VLDL; 3%). The lipid composition of these lipoproteins was minimally affected. De novo synthesis of apo A-I, apo B-100, and apo B-48 was also markedly reduced by TNF-alpha. Sphingomyelinase activity was not increased and cell content of sphingomyelin was not altered, suggesting that inhibitory effects on lipid and apoprotein of TNF-alpha were not mediated by the ceramide pathway. Our results indicate that TNF-alpha may play a role in modulating intestinal lipid metabolism, thus affecting circulating lipoproteins.

Intracerebral implantation of hydrogel-coupled adhesion peptides: tissue reaction

Arg-Gly-Asp peptides (RGD) were synthesized and chemically coupled to the bulk of N-(2-hydroxypropyl) methacrylamide-based polymer hydrogels. Fourier Transform Infrared Spectroscopy (FTIR) and amino acid analysis confirmed the peptide coupling to the polymer. Activated and control (unmodified) polymer matrices were stereotaxically implanted in the striata of rat brains, and two months later the brains were processed for immunohistochemistry using antibodies for glial acidic fibrillary protein (GFAP), laminin and neurofilaments. RGD-containing polymer matrices promoted stronger adhesion to the host tissue than the unmodified polymer matrices. In addition, the RGD-grafted polymer implants promoted and supported the growth and spread of GFAP-positive glial tissue onto and into the hydrogels. Neurofilament-positive fibers were also seen running along the surface of the polymer and, in some instances, penetrating the matrix. These findings are discussed in the context of using bioactive polymers as a new approach for promoting tissue repair and axonal regeneration of damaged structures of the central nervous system.

Interleukin-2 production in pediatric inflammatory bowel disease: evidence for dissimilar mononuclear cell function in Crohn's disease and ulcerative colitis

Crohn's disease (CD) and ulcerative colitis (UC) represent clinically distinct chronic inflammatory bowel diseases (IBD) of unknown etiology. Although the mucosal immune system is implicated in their pathogenesis, immunological differences between the two disorders are not well defined. The aim of this study was to compare in vitro mucosal T-lymphocyte function in CD and UC. Peripheral blood mononuclear cell interleukin-2 (IL-2) production was similar in pediatric IBD and control patients under unstimulated conditions, but was significantly increased in response to phytohemagglutinin (PHA) stimulation for the UC group. Lamina propria mononuclear cells (LPMNC) isolated from colonic resections in IBD patients had significantly lower spontaneous proliferation and IL-2 production in vitro than did LPMNC of control patients. In contrast, significantly greater IL-2 production was detected when the LPMNC of CD patients were cultured with PHA, in comparison with those of UC or control patients. When indomethacin, a prostaglandin synthetase inhibitor, was added to the cultures, significantly increased IL-2 secretion was observed for CD LPMNC, but not for UC cultures, under both stimulated and unstimulated conditions. These findings demonstrate abnormal LPMNC IL-2 production in IBD. Furthermore, our data suggest that inhibition of the prostaglandin synthetase pathway upregulates IL-2 production by LPMNC in CD. These results support the hypothesis that immunoregulatory mechanisms controlling IL-2 production differ between CD and UC.

[The pneumococcal vaccine. Its efficacy in patients 55 and over]

Three recent articles are examined in which research using the double-blind randomised clinical trial, the case control study, and the quasi-cohort study is described. Understanding the advantages and disadvantages of these methods makes it easier to grasp the pneumococcal vaccine controversy and make an informed choice.

Ontogenetic study of early brain stem projections to the spinal cord in the rat

In an attempts to describe the early development of the brain stem-spinal projections, we implanted DiI crystals at the C3 level of the spinal cord of 13- and 14-day fixed embryos. After a diffusion period of 2 to 4 months, neurons of the rhombencephalic reticular formation were retrogradely labeled by the tracer. This group of neurons was situated ventromedially in the tegmentum. Their axons coursed into the ventral marginal layer at bulbar levels and entered the ventral funiculus when reaching the spinal cord. Neurons of the lateral vestibular nucleus were also labeled and gave rise to descending fibers that gradually moved medially and entered the spinal cord in the ventral funiculus. In the mesencephalon, labeled cell bodies of the interstitial nucleus of Cajal (InC) were found lying ventrally in the tegmentum, at the rostral end of the medial longitudinal fasciculus (mlf), in which their axons coursed. Also, in the midbrain, several cells lying dorsal to the InC, with axons descending in the lateral tegmentum, were tentatively identified as part of the mesencephalic reticular formation.

Evaluation of two cross-linked collagen gels implanted in the transected spinal cord

In previous experiments, we have shown that spinal axons grow into a collagen matrix implanted between the stumps of a transected spinal cord. However, the matrix became denatured after 2 to 3 months. To improve the stability and the durability of the collagen gel implants, collagen was coprecipitated with chondroitin-6-sulfate (C-6-S) or chemically cross-linked with carbodiimide (CD). The spinal cords were taken out after 3 days, 1, 3, or 6 months and analyzed using different histological and tracing techniques. The cross-linked collagen matrices underwent major structural changes. Cross-linking treatments improved the stability of collagen implants which withstood at least 6 months. Axons revealed with DiI or silver staining crossed the proximal interface and grew into the bioimplants. Some axons were also followed across the distal bioimplant-spinal interface in DiI treated tissues. This study suggests that cross-linking the collagen hydrogel has improved the mechanical properties of the matrix, modified the normal scarring process, and favored axonal regeneration.

The disposition of early-generated neurons in the rat embryo predicts the pattern of major axonal tracts

During embryogenesis, the fiber tracts grow in a highly stereotyped pattern. A very small number of predetermined paths, preceding the growth of fasciculi, are present in the young neural tube (10-12, 15). What is the origin of these substrate pathways defined by Katz et al. (16) as "... a set of similar guidance cues which are aligned in a continuous discrete pathway..."? Could the first neurons play a role in the guidance of early nerve fibers? Observations in the brain stem revealed the presence of two longitudinal columns of early-generated neurons. These longitudinal columns were associated with well-differentiated marginal zones, characterized by cell-free spaces and representing the prospective site of the medial longitudinal (mlf) and lateral longitudinal (llt) tracts. Nerve fibers were also traced in the brain stem of young embryos. Axons were seen to travel in the early mlf and llt, in close proximity to the regions of early-generated neuronal columns. The data suggest that the precocious neurons that are organized in a definite pattern could somehow be involved in the guidance of some longitudinal axonal tracts, either by directly promoting the formation of an adequate terrain in the marginal layer, or by inducing other cells to do so.