Molecular modeling and simulation studies of SELEX-derived high-affinity DNA aptamers to the Ebola virus nucleoprotein

Ebola viral disease (EVD) is a highly infectious and potentially fatal illness with a case fatality rate ranging from 25% to 90%. To effectively control its spread, there is a need for rapid, reliable and lowcost point-of-care (P OC) diagnostic tests. While various EVD diagnostic tests exist, few are P OC tests, and many are not cost-effective. The use of antibodies in these tests has limitations, prompting the exploration of aptamers as potential alternatives. Various proteins from the Ebola virus (EBOV) proteome, including EBOV nucleoprotein (NP), are considered viable targets for diagnostic assays. A previous study identified three aptamers (Apt1. Apt2 and Apt3) with high affinity for EBOV NP using systemic evolution of ligands by exponential enrichment (SELEX). This study aimed to employ in silico methods, such as Phyre2, RNAfold, RNAComposer, HADDOCK and GROMACS, to model the structures of EBOV NP and the aptamers, and to investigate their binding. The in silico analysis revealed successful binding of all the three aptamers to EBOV NP, with a suggested ranking of Apt1 > Apt2 > Apt3 based on binding affinity. Microscale thermophoresis (MST) analysis confirmed the binding, providing dissociation constants of 25 ± 2.84, 56 ± 2.76 and 140 ±3.69 nM for Apt1, Apt2 and Apt3, respectively. The study shows that the findings of the in silico analysis was in agreement with the MST analysis. Inclusion of these in silico approaches in diagnostic assay development can expedite the selection of candidate aptamers, potentially overcoming challenges associated with aptamer application in diagnostics.Communicated by Ramaswamy H. Sarma.

Observations about declining fertility in a feline breeding colony

Feline breeding colonies are important to the feline industry by preserving traits desirable for a particular breed or in research settings by maintaining medically valuable genetic traits. As breeding females age, their reproductive efficiency declines. The objective of this study was to determine the most common causes of infertility in breeding females that were producing fewer kittens. Knowing the cause and average age of infertility would allow management decisions to be made for the betterment of the colony. The medical records of 70 queens retired from breeding from a single research colony were examined for litter size and number, fertility over their lifespan, and age and reason for removal from breeding stock. Sections of uterus and ovaries were evaluated using gross and histopathological examination for a subset of these queens (46). The data suggests that mature, continuously breeding female cats may show signs of reduced fertility (infertile matings or reduced litter size) as early as 3 years of age and may be a result of undiagnosed Cystic Endometrial Hyperplasia (CEH), endometritis, pyometra and/or ovarian cysts. Evaluation of breeding queens should include periodic ultrasounds to monitor for ovarian cysts and evidence of CEH. Retiring animals from breeding once signs of infertility become apparent is recommended.

Immunoinformatics design of a novel epitope-based vaccine candidate against dengue virus

Dengue poses a global health threat, which will persist without therapeutic intervention. Immunity induced by exposure to one serotype does not confer long-term protection against secondary infection with other serotypes and is potentially capable of enhancing this infection. Although vaccination is believed to induce durable and protective responses against all the dengue virus (DENV) serotypes in order to reduce the burden posed by this virus, the development of a safe and efficacious vaccine remains a challenge. Immunoinformatics and computational vaccinology have been utilized in studies of infectious diseases to provide insight into the host-pathogen interactions thus justifying their use in vaccine development. Since vaccination is the best bet to reduce the burden posed by DENV, this study is aimed at developing a multi-epitope based vaccines for dengue control. Combined approaches of reverse vaccinology and immunoinformatics were utilized to design multi-epitope based vaccine from the sequence of DENV. Specifically, BCPreds and IEDB servers were used to predict the B-cell and T-cell epitopes, respectively. Molecular docking was carried out using Schrödinger, PATCHDOCK and FIREDOCK. Codon optimization and in silico cloning were done using JCAT and SnapGene respectively. Finally, the efficiency and stability of the designed vaccines were assessed by an in silico immune simulation and molecular dynamic simulation, respectively. The predicted epitopes were prioritized using in-house criteria. Four candidate vaccines (DV-1-4) were designed using suitable adjuvant and linkers in addition to the shortlisted epitopes. The binding interactions of these vaccines against the receptors TLR-2, TLR-4, MHC-1 and MHC-2 show that these candidate vaccines perfectly fit into the binding domains of the receptors. In addition, DV-1 has a better binding energies of - 60.07, - 63.40, - 69.89 kcal/mol against MHC-1, TLR-2, and TLR-4, with respect to the other vaccines. All the designed vaccines were highly antigenic, soluble, non-allergenic, non-toxic, flexible, and topologically assessable. The immune simulation analysis showed that DV-1 may elicit specific immune response against dengue virus. Moreover, codon optimization and in silico cloning validated the expressions of all the designed vaccines in E. coli. Finally, the molecular dynamic study shows that DV-1 is stable with minimum RMSF against TLR4. Immunoinformatics tools are now applied to screen genomes of interest for possible vaccine target. The designed vaccine candidates may be further experimentally investigated as potential vaccines capable of providing definitive preventive measure against dengue virus infection.

Development of Effective Therapeutic Molecule from Natural Sources against Coronavirus Protease

The SARS-CoV-2 main protease (M^pro) is one of the molecular targets for drug design. Effective vaccines have been identified as a long-term solution but the rate at which they are being administered is slow in several countries, and mutations of SARS-CoV-2 could render them less effective. Moreover, remdesivir seems to work only with some types of COVID-19 patients. Hence, the continuous investigation of new treatments for this disease is pivotal. This study investigated the inhibitory role of natural products against SARS-CoV-2 M^pro as repurposable agents in the treatment of coronavirus disease 2019 (COVID-19). Through in silico approach, selected flavonoids were docked into the active site of M^pro. The free energies of the ligands complexed with M^pro were computationally estimated using the molecular mechanics-generalized Born surface area (MM/GBSA) method. In addition, the inhibition process of SARS-CoV-2 Mpro with these ligands was simulated at 100 ns in order to uncover the dynamic behavior and complex stability. The docking results showed that the selected flavonoids exhibited good poses in the binding domain of M^pro. The amino acid residues involved in the binding of the selected ligands correlated well with the residues involved with the mechanism-based inhibitor (N3) and the docking score of Quercetin-3-O-Neohesperidoside (−16.8 Kcal/mol) ranked efficiently with this inhibitor (−16.5 Kcal/mol). In addition, single-structure MM/GBSA rescoring method showed that Quercetin-3-O-Neohesperidoside (−87.60 Kcal/mol) is more energetically favored than N3 (−80.88 Kcal/mol) and other ligands (Myricetin 3-Rutinoside (−87.50 Kcal/mol), Quercetin 3-Rhamnoside (−80.17 Kcal/mol), Rutin (−58.98 Kcal/mol), and Myricitrin (−49.22 Kcal/mol). The molecular dynamics simulation (MDs) pinpointed the stability of these complexes over the course of 100 ns with reduced RMSD and RMSF. Based on the docking results and energy calculation, together with the RMSD of 1.98 ± 0.19 Å and RMSF of 1.00 ± 0.51 Å, Quercetin-3-O-Neohesperidoside is a better inhibitor of M^pro compared to N3 and other selected ligands and can be repurposed as a drug candidate for the treatment of COVID-19. In addition, this study demonstrated that in silico docking, free energy calculations, and MDs, respectively, are applicable to estimating the interaction, energetics, and dynamic behavior of molecular targets by natural products and can be used to direct the development of novel target function modulators.

Aptamer-Based Diagnostic Systems for the Rapid Screening of TB at the Point-of-Care

The transmission of Tuberculosis (TB) is very rapid and the burden it places on health care systems is felt globally. The effective management and prevention of this disease requires that it is detected early. Current TB diagnostic approaches, such as the culture, sputum smear, skin tuberculin, and molecular tests are time-consuming, and some are unaffordable for low-income countries. Rapid tests for disease biomarker detection are mostly based on immunological assays that use antibodies which are costly to produce, have low sensitivity and stability. Aptamers can replace antibodies in these diagnostic tests for the development of new rapid tests that are more cost effective; more stable at high temperatures and therefore have a better shelf life; do not have batch-to-batch variations, and thus more consistently bind to a specific target with similar or higher specificity and selectivity and are therefore more reliable. Advancements in TB research, in particular the application of proteomics to identify TB specific biomarkers, led to the identification of a number of biomarker proteins, that can be used to develop aptamer-based diagnostic assays able to screen individuals at the point-of-care (POC) more efficiently in resource-limited settings.

Trophoblast Glycoprotein (TPGB/5T4) in Human Placenta: Expression, Regulation, and Presence in Extracellular Microvesicles and Exosomes

BACKGROUND

Many parallels exist between growth and development of the placenta and that of cancer. One parallel is shared expression of antigens that may have functional importance and may be recognized by the immune system. Here, we characterize expression and regulation of one such antigen, Trophoblast glycoprotein (TPGB; also called 5T4), in the placenta across gestation, in placentas of preeclamptic (PE) pregnancies, and in purified microvesicles and exosomes.

METHODS

Trophoblast glycoprotein expression was analyzed by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry. Regulation of 5T4 in cytotrophoblast cells was examined under either differentiating conditions of epidermal growth factor or under varying oxygen conditions. Microvesicles and exosomes were purified from supernatant of cultured and perfused placentas.

RESULTS

Trophoblast glycoprotein expression was prominent at the microvillus surface of syncytiotrophoblast and on the extravillous trophoblast cells, with minimal expression in undifferentiated cytotrophoblasts and normal tissues. Trophoblast glycoprotein expression was elevated in malignant tumors. In cytotrophoblasts, 5T4 was induced by in vitro differentiation, and its messenger RNA (mRNA) was increased under conditions of low oxygen. PE placentas expressed higher 5T4 mRNA than matched control placentas. Trophoblast glycoprotein was prominent within shed placental microvesicles and exosomes.

CONCLUSION

Given the potential functional and known immunological importance of 5T4 in cancer, these studies reveal a class of proteins that may influence placental development and/or sensitize the maternal immune system. In extravillous trophoblasts, 5T4 may function in epithelial-to-mesenchymal transition during placentation. The role of syncytiotrophoblast 5T4 is unknown, but its abundance in shed syncytial vesicles may signify route of sensitization of the maternal immune system.

Dissimilation of Carbon Monoxide to Acetic Acid by Glucose-Limited Cultures of Clostridium thermoaceticum

Clostridium thermoaceticum was cultivated in glucose-limited media, and the dissimilation of CO to acetic acid was evaluated. We found that cultures catalyzed the rapid dissimilation of CO to acetic acid and CO(2), with the stoichiometry obtained for conversion approximating that predicted from the following reaction: 4CO + 2H(2)O --> CH(3)CO(2)H + 2CO(2). Growing cultures formed approximately 50 mmol (3 g) of CO-derived acetic acid per liter of culture, with the rate of maximal consumption approximating 9.1 mmol of CO consumed/h per liter of culture. In contrast, resting cells were found not to dissimilate CO to acetic acid. CO was incorporated, with equal distribution between the carboxyl and methyl carbons of acetic acid when the initial cultivation gas phase was 100% CO, whereas CO(2) preferentially entered the carboxyl carbon when the initial gas phase was 100% CO(2). Significantly, in the presence of saturating levels of CO, CO(2) preferentially entered the methyl carbon, whereas saturating levels of CO(2) yielded CO-derived labeling predominantly in the carboxyl carbon. These findings are discussed in relation to the path of carbon flow to acetic acid.

Phase II meningococcal B vesicle vaccine trial in New Zealand infants

BACKGROUND

A tailor-made serogroup B outer membrane vesicle vaccine was evaluated in the context of a serogroup B meningococcal epidemic dominated by Neisseria meningitidis strain B:4:P1.7b,4.

OBJECTIVE

To determine the safety, reactogenicity and immunogenicity in infants aged 6-8 months of a meningococcal B vaccine developed against the New Zealand epidemic strain.

DESIGN, SETTING AND PARTICIPANTS

Observer-blind, randomised, controlled trial conducted in 296 healthy infants in Auckland, New Zealand.

INTERVENTION

Infants were randomised 4:1 to receive three doses of New Zealand candidate vaccine (epidemic strain NZ98/254, B:4:P1.7b,4) or meningococcal C conjugate vaccine at 6-weekly intervals.

MAIN OUTCOME MEASURES

Immune response was determined by human complement mediated serum bactericidal assay. Sero-response was a fourfold or greater rise in titre compared to baseline, with baseline titres <4 required to increase to >or=8. Blood samples were taken before vaccination, 6 weeks after dose two, and 4 weeks after dose three. Local and systemic reactions were recorded for 7 days following vaccination.

RESULTS

Sero-response to the candidate vaccine strain, NZ98/254, was demonstrated in 74% of vaccinees (95% CI: 68% to 80% intention-to-treat; 67% to 79% per protocol) after three doses of New Zealand candidate vaccine. No meningococcal C conjugate vaccine recipients were sero-responders to NZ98/254 after three doses. Both vaccines were well tolerated with no vaccine related serious adverse events.

CONCLUSIONS

Our data indicate that the New Zealand candidate vaccine administered in three doses to this group of 6-8-month-old infants was safe and immunogenic against the candidate vaccine strain NZ98/254 (Neisseria meningitidis B:4:P1.7b,4).

Once-daily amoxicillin versus twice-daily penicillin V in group A beta-haemolytic streptococcal pharyngitis

BACKGROUND

Rheumatic fever is a preventable chronic disease preceded by group A beta-haemolytic streptococcal (GABHS) pharyngitis.

OBJECTIVE

To test the non-inferiority of once-daily (QD) oral amoxicillin to the recommended twice-daily (BID) oral penicillin V in GABHS pharyngitis.

METHODS

This was a randomised non-inferiority trial carried out in a school-based clinic in New Zealand. Children presenting with GABHS pharyngitis were randomised to oral amoxicillin 1500 mg QD (or 750 mg if bodyweight was <or=30 kg) or to oral penicillin V 500 mg BID (or 250 mg if bodyweight was <or=20 kg) for 10 days. Observed medication and weekend diary cards were used to monitor adherence.

OUTCOME

Eradication of GABHS, determined with follow-up throat cultures on days 3-6, 12-16 and 26-36. GABHS isolates were serotyped to distinguish bacteriological treatment failures (and relapses) from new acquisitions. Non-inferiority was defined as an upper 95% confidence limit (CL) for the difference in success of eradication in the amoxicillin and penicillin V treatment groups of <or=10%.

RESULTS

353 children with positive throat swabs for GABHS were randomised to amoxicillin (n = 177) or penicillin V (n = 176). The upper 95% CL for the differences in positive cultures between the antibiotics was 4.9% at days 3-6, 6.5% at days 12-16 and 8.5% at days 26-36. Treatment failures (including relapses) occurred at each visit in 5.8%, 12.7% and 10.7% of amoxicillin recipients and 6.2%, 11.9% and 11.3% of penicillin V recipients, respectively. No significant differences in resolution of symptoms were noted between treatment groups. One case of unsubstantiated acute rheumatic fever occurred after 7 days of amoxicillin.

CONCLUSION

In this adequately powered study, once-daily oral amoxicillin is not inferior to twice-daily penicillin V for the treatment and eradication of GABHS in children with pharyngitis.

Invasive pneumococcal disease in New Zealand 1998-2005: capsular serotypes and antimicrobial resistance

Isolates from 3903 cases of invasive pneumococcal disease (IPD) were referred to the national reference laboratory over the 8 years, 1998-2005, as part of the laboratory-based surveillance of this disease in New Zealand. All isolates were serotyped and their antimicrobial susceptibility was tested. The incidence of IPD was highest in young children, with an average annual incidence of 100.8/100,000 in infants aged <2 years. There were changes in the prevalence of several of the serotypes during the 8-year period. Overall the seven serotypes included in the 7-valent pneumococcal conjugate vaccine, 4, 6B, 9V, 14, 18C, 19F and 23F, were the most common serotypes and accounted for 80.9% of the disease in infants aged <2 years. There was no overall change in penicillin resistance or non-susceptibility during the 8 years, and rates were 7.1% and 17.1%, respectively, in 2005. In contrast, cefotaxime and erythromycin resistance increased to reach 3.1% and 12.2%, respectively, by 2005.

Differential effects of vitamin D receptor activators on vascular calcification in uremic rats

Vascular calcification is associated with cardiovascular disease, the most common cause of death in chronic kidney disease (CKD). Patients with CKD are treated with vitamin D receptor activators (VDRAs); therefore, we determined if this treatment affects vascular calcification. Uremic rats were given vehicle, calcitriol, paricalcitol, or doxercalciferol three times a week for 1 month. Calcitriol significantly increased the serum calcium-phosphate product and aortic calcium content. Paricalcitol had no effect but the same dose of doxercalciferol significantly increased the calcium-phosphate product and the aortic calcium content, the latter being confirmed by von Kossa staining. To see if the increased aortic calcium was due to an increased serum calcium-phosphate product or to a differential effect of the two VDRAs, we lowered the dose of doxercalciferol and increased the dose of paricalcitol. A lower doxercalciferol did not increase the calcium-phosphate product but increased the aortic calcium content. A higher dose of paricalcitol still had no effect. Doxercalciferol treatment increased the mRNA and protein expression of the bone-related markers Runx2 and osteocalcin in the aorta, whereas paricalcitol did not. Hence, different VDRAs have different effects on vascular calcification in uremic rats. The effects are independent of the serum calcium-phosphate product suggesting independent mechanisms.

The VR2 epitope on the PorA P1.7-2,4 protein is the major target for the immune response elicited by the strain-specific group B meningococcal vaccine MeNZB

A protracted epidemic of group B meningococcal disease in New Zealand led to the testing of a strain-specific tailor-made vaccine, MeNZB. Immunogenicity levels achieved during age group trials enabled New Zealand's regulatory authority to grant licensure to deliver MeNZB to all individuals under age 20. During the trials target strains for serum bactericidal antibody measurements included the vaccine target strain NZ98/254 and two comparator epidemic-type strains (NZ94/167 and NZ02/09). In this study, 12 other strains differing variously from the vaccine strain by their capsular group, PorB type, and PorA variable region specificities, or PorA expression, were used as target strains. The PorA specificity of the serum bactericidal antibody responses to the vaccine was determined for 40 vaccinees. Sets of 10 pre- and postvaccination sera were chosen randomly from the young infant, older infant, toddler, and school-age group trials. Antibody recognition of linearized PorA proteins was also determined using immunoblotting. Across all age groups vaccine-induced serum bactericidal antibodies specifically targeted the VR2 P1.4 epitope of the PorA P1.7-2,4 protein irrespective of the PorB type and/or capsular type of the target strain. Deletion of amino acids within the VR2 epitope or replacement of the epitope through genetic exchange allowed strains variously to resist antibody-directed complement-mediated lysis and negated PorA-specific antibody recognition in immunoblots. The demonstration that the immunodominant antibody response was specifically for the VR2 P1.4 epitope of the PorA protein supports the public health decision to use a strain-specific vaccine for the control of New Zealand's epidemic of meningococcal disease.

Stability of PorA during a meningococcal disease epidemic

Meningococci causing New Zealand's epidemic, which began in 1991, are defined as group B, serosubtype P1.4 (subtype P1.7-2,4), belonging to the ST-41/ST-44 complex, lineage III. Of the 2,358 group B isolates obtained from disease cases from 1991 through 2003, 85.7% (2,021 of 2,358) were determined to be serosubtype P1.4. Of the remaining isolates, 156 (6.6%) were not serosubtypeable (NST). Molecular analysis of the porA gene from these B:NST meningococcal isolates was used to determine the reason. Most NST isolates (156, 88.5%) expressed a PorA that was distinct from P1.7-2,4 PorA. Fifteen isolates expressed variants of P1.7-2,4 PorA, and a further three expressed P1.7-2,4 PorA without any sequence variation. These three isolates expressed P1.7-2,4 PorA at very low levels, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, and showed variation in the porA promoter region. Among the 15 meningococcal isolates expressing variants of P1.7-2,4 PorA, 11 different sequence variations were found. Compared with the P1.7-2,4 PorA sequence, the sequences of these variants contained deletions, insertions, or single-nucleotide substitutions in the VR2 region of the protein. Multilocus restriction typing was used to assess the clonal derivations of B:NST case isolates. Meningococcal isolates expressing distinct PorA proteins belonged mostly to clonal types that were unrelated to the epidemic strain, whereas all meningococcal isolates expressing variants of P1.7-2,4 PorA belonged to the ST-41/ST-44 complex, lineage III. These results, together with those obtained serologically, demonstrate that the P1.7-2,4 PorA protein of meningococci responsible for New Zealand's epidemic has remained relatively stable over 13 years and support the use of a strain-specific outer membrane vesicle vaccine to control the epidemic.

Application of the NMR-MOUSE to food emulsions

The application of the NMR-MObile Universal Surface Explorer (NMR-MOUSE) to study food systems is evaluated using oil-in-water emulsions, and the results are compared to those obtained using a conventional low-field NMR (LF-NMR) instrument. The NMR-MOUSE is a small and portable LF-NMR system with a one-sided magnet layout that is used to replace the conventional magnet and probe on a LF-NMR instrument. The high magnetic field gradients associated with the one-sided MOUSE magnet result in NMR signal decays being dominated by molecular diffusion effects, which makes it possible to discriminate between the NMR signals from oil and water. Different data acquisition parameters as well as different approaches to the analysis of the NMR data from a range of oil-in-water emulsions are evaluated, and it is demonstrated how the concentration of oil and water can be determined from the NMR-MOUSE signals. From these model systems it is concluded that the NMR-MOUSE has good potential for the quantitative analysis of intact food products.

Case report: gastric schwannoma: MRI findings

MRI features are described in a case of gastric schwannoma. A large, discretely marginated, multilobular mass was seen adjacent to the gastric antrum with the epicentre of the mass in the gastrocolic ligament. The overall signal pattern was low on T(1) weighted images and moderate to markedly elevated on T(2) weighted images. Post-gadolinium sequences demonstrate slow but fairly uniform enhancement throughout the mass.

Early-onset neonatal group B streptococcal infections in New Zealand 1998-1999

OBJECTIVE

To determine in New Zealand infants the attack rates, risk factors, preventive policies, strain serotype and antibiotic susceptibilities of early-onset neonatal group B streptococcus (GBS) infection.

METHOD

A 2-year prospective active surveillance study was conducted in New Zealand's 19 neonatal units. Cases had to present within 48 h of delivery, be unwell, possess abnormal haematological indices and have GBS isolated from sterile sites.

RESULTS

Of the 112 402 infants born in New Zealand during 1998-1999, 56 had early-onset GBS infection, an attack rate of 0.5 per 1000 live births (95% confidence interval [CI] 0.38, 0.65). Seven had meningitis and there was one death (case fatality rate of 1.8%; upper 95% CI 9.5%). Univariate analysis identified young maternal age, parity, preterm labour, prolonged membrane rupture, maternal fever and assisted delivery as risk factors. Preventive policies for GBS were reported by 14 (74%) obstetric centres associated with neonatal units. Of the 56 cases, five (9%) were born to mothers receiving intrapartum antibiotics, 32 (57%) had mothers with risk factors but were not treated with antibiotics, and 19 (34%) were born to mothers without identifiable risk factors for GBS prevention. Serotypes Ia and III predominated, while two isolates were resistant to erythromycin and/or clindamycin.

CONCLUSIONS

Rates of early-onset GBS infection are similar to other countries following the introduction of prevention policies. Further reductions are possible with full implementation of these guidelines. Meanwhile, emergence of antibiotic resistance complicates the management of women with penicillin allergy. Vaccine development therefore remains a priority.

A molecular description of the gelation mechanism of konjac mannan

A molecular level description of the time course of the gelation of the polysaccharide konjac mannan (KM) is presented and the role of alkali addition is considered in detail. NMR relaxometry is utilized as a complementary methodology to mechanical spectroscopy in order to probe events occurring as a prelude to network formation, and high-resolution NMR is used to follow the deactetylation process. It is shown that the addition of alkali plays an important solubilizing role in addition to facilitating the deacetylation of the chain. Deacetylation is important both in reducing the inherent aqueous solubility of the polymer and in progressively negating the alkali-induced polyelectrolytic nature of the polysaccharide chain via reaction induced pH changes. It is proposed that observed induction periods following alkali addition (during which the elastic modulus does not rise) are not simply deacetylation delays but are related to the aggregation kinetics of the deacetylated material.

Imaging of benign and malignant focal liver lesions

Over the past 15 years, MR imaging of the abdomen and pelvis has progressed significantly. Although initially found to be useful as an adjunct to CT imaging for selective applications, MR imaging now is establishing a role as a primary diagnostic technique. Increasing evidence shows that MR imaging has advantages over CT regarding diagnostic sensitivity and specificity for many abnormalities of solid organs, bile and pancreatic ducts, bowel, peritoneum, and retroperitoneum. This article discusses and contrasts current MR and CT techniques for imaging the liver and discusses the relative ability to identify and diagnose focal liver disease.

A 10-year serogroup B meningococcal disease epidemic in New Zealand: descriptive epidemiology, 1991-2000

OBJECTIVE

New Zealand has experienced an epidemic of meningococcal disease since 1991. This paper describes the characteristics of this epidemic during its first 10 years (1991-2000), current control measures, and potential future interventions.

METHODOLOGY

Meningococcal disease surveillance in New Zealand uses combined notification and laboratory data. Population census data from 1991 and 1996 were used to calculate disease rates.

RESULTS

The annual incidence of meningococcal disease increased from 53 cases (1.6 per 100 000 population) in the pre-epidemic year of 1990 to a peak of 613 (16.9 per 100000) in 1997, followed by consistently raised rates. Over the 1996-2000 period, there was an average of 502 cases per year (13.9 per 100 000). The epidemic has resulted in 3547 cases since 1991 approximately 3000 in excess of the number expected based on pre-epidemic disease incidence. Of the total cases, 158 (4.5%) were fatal. A disproportionately large number of cases have been in Maori and Pacific Islands children in the northern part of the North Island of New Zealand. Since 1991, the epidemic has increasingly been dominated by serogroup B meningococci with subtype P1.7b,4, which by 2000 accounted for 84.6% of all cases for whom this testing was carried out. The majority of these organisms were characterised as B:4:P1.7b,4.

CONCLUSION

Meningococcal disease rates are likely to remain elevated in New Zealand for at least several more years. A vaccine which could induce immunity to the P1.7b,4 PorA subtype may have a role in controlling this epidemic. Efforts are underway to obtain and trial such a vaccine. Measures are also underway to reduce overcrowded living conditions which are contributing to the epidemic. Early recognition and antibiotic treatment of cases improves outcomes and should continue to be promoted. Integrated notification and laboratory-based surveillance of meningococcal disease provides relatively complete surveillance of this disease in New Zealand and has supported the development of public health interventions.

Influence of thermal history on the structural and mechanical properties of agarose gels

Using a multitechnique approach, two temperature domains have been identified in agarose gelation. Below 35 degrees C, fast gelation results in strong, homogeneous and weakly turbid networks. The correlation length, evaluated from the wavelength dependence of the turbidity, is close to values of pore size reported in the literature. Above 35 degrees C, gelation is much slower and is associated with the formation of large-scale heterogeneities that can be monitored by a marked change in the wavelength dependence of turbidity and visualised by transmission electron microscopy. Curing agarose gels at temperatures above 35 degrees C, and then cooling them to 20 degrees C, produces much weaker gels than those formed directly at 20 degrees C. Dramatic reductions in the elastic modulus and failure strain and stress are found in this case as a result of demixing during cure. An interpretation, based on the kinetic competition between osmotic forces (in favor of phase separation) and elastic forces (that prevent it) is proposed.

Report from the Council of Emergency Medicine Residency Directors subcommittee on graduate medical education funding: effects of decreased medicare support

INTRODUCTION

Recent changes by the Health Care Financing Administration (HCFA) have resulted in decreased Medicare support for emergency medicine (EM) residencies.

OBJECTIVE

To determine the effects of reduced graduate medical education (GME) funding support on residency size, resident rotations, and support for a fourth postgraduate year (PGY) of training and for residents with previous training.

METHODS

A 36-question survey was developed by the Council of Emergency Medicine Residency Directors (CORD) committee on GME funding and sent to all 122 EM program directors (PDs). Responses were collected by the Society for Academic Emergency Medicine (SAEM) office and blinded with respect to the institution.

RESULTS

Of 122 programs, 109 (89%) responded, of which 78 were PGY 1-3 programs, 19 were PGY 2-4, and 12 were PGY 1-4. The PDs were asked specifically whether there were changes in program size due to changes in Medicare reimbursement. Although few programs (12%) decreased their size or planned to decrease their size, 39% had discussions regarding decreasing their size. Thirty percent of the PDs responded that other programs at their institution had already decreased their size; 26% of the PDs had problems with financing outside rotations; and 24% had a decrease in off-service residents in their emergency departments (EDs). Only seven (6%) of programs paid residents from practice plan dollars, while most (82%) were fully supported by federal GME funding. Nearly all four-year programs (97%) received full resident salary support from their institutions and 77% of programs accept residents with previous training.

CONCLUSIONS

Nearly all EM programs are fully supported by their institutions, including the fourth postgraduate year. Most programs take residents with previous training. Although few programs have reduced their size, many are discussing this. Many programs have had difficulty with funding off-service rotations and many have had decreased numbers of off-service residents in their EDs. Recent GME funding changes have had adverse effects on EM residency programs.

Hepatocyte growth factor inhibits apoptosis after ischemic renal injury in rats

Several studies have determined that growth factors, including hepatocyte growth factor (HGF), have a crucial role in the regenerative process of renal tubules after ischemic or toxic insult. Recent research has ascertained that as well as necrotic cell death, there is evidence of apoptosis after an acute renal injury. We attempted to determine the effect of HGF on apoptosis after ischemic renal injury in rats. We administered HGF or vehicle to 12 rats after ischemic insult and compared them with 6 sham-operated controls. Rats were killed at 48 hours, and histopathologic assessments were performed on the renal tissue. The microscale autoradiographic method was used for qualitative analysis of DNA fragmentation. This method was chosen over the widely used ethidium bromide-staining method because it increases the sensitivity of detection of apoptotic DNA. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling histopathologic staining was used to identify apoptosis in situ. Apoptotic changes were clearly shown by electron microscopy in vehicle-treated animals. Despite showing profound evidence of tubular necrosis, apoptotic changes were markedly reduced in HGF-treated animals compared with vehicle-treated animals. DNA-laddering analysis further confirmed the antiapoptotic effect of HGF. To our knowledge, this is the first in vivo illustration of the inhibitory activity of a growth factor on apoptosis in the setting of tubular necrosis. The role of apoptosis in the setting of acute renal failure has not been elucidated; thus, additional research is necessary to determine the significance of these findings.

Use of flexion-extension radiographs of the cervical spine in blunt trauma

STUDY OBJECTIVE

Flexion-extension (F/E) radiographs of the cervical spine are often used in patients with blunt trauma when the evaluating physician remains concerned about bony or ligamentous injuries despite negative or nondiagnostic standard radiographs. The use of this approach has never been addressed in a large prospective study. We sought to determine the clinical factors associated with ordering F/E views and the incidence of diagnostic F/E films in patients with a normal 3-view cervical spine series.

METHODS

Patients with blunt trauma selected for radiographic cervical spine imaging at 21 participating institutions in the National Emergency X-Radiography Utilization Study project underwent standard 3-view (cross-table lateral, anteroposterior, and odontoid views) series, as well as any other imaging deemed necessary by their physicians. Injuries detected by means of screening radiography were then compared with final injury status for each patient, as determined by review of all radiographic studies. Patients who underwent F/E views were analyzed separately.

RESULTS

Of 818 patients ultimately found to have cervical spine injury, 86 (10.5%) underwent F/E testing. Two patients sustained stable bony injuries detected only on F/E views. Four other patients had a subluxation detected only on F/E views, but all had other injuries apparent on routine cervical spine imaging.

CONCLUSION

F/E imaging adds little to the acute evaluation of patients with blunt trauma. Other approaches, including magnetic resonance imaging, computed tomography, or delayed F/E, in the presence of specific clinical concerns would seem to provide a more reasonable approach to adjunctive imaging.

Acute renal failure: common occurrence of preservation of corticomedullary differentiation on MR images

The purpose of this study was to evaluate the relationship between renal corticomedullary differentiation (CMD) on MR imaging and serum creatinine (sCr) level in patients with acute renal failure (ARF). Twenty-one patients with ARF were retrospectively investigated. In all 21 patients, sCr levels were obtained on the same date as the MR study, and within 8 days before and after the MR study. CMD was assessed on non-contrast T(1)-weighted images and immediate post-gadolinium spoiled gradient echo (Gd-SGE) images. Presence of CMD was graded into 3 groups as 'preserved', 'intermediate', or 'loss'. On non-contrast T(1)-weighted images, 12/21 (57%) showed loss of CMD and 9/21 (43%) showed preserved CMD. On immediate Gd-SGE images, 5/21 (24%) showed loss of CMD, 12/21 (57%) preserved CMD, and 4/21 (19%) intermediate CMD. The sCr levels of 9 patients with preserved CMD on non-contrast T(1)-weighted images ranged from 1.4 to 10.5 mg/dl (mean 4.6 mg/dl), while those of 12 patients with loss of CMD ranged from 1.6 to 7.6 mg/dl (mean 4.8 mg/dl), which was not statistically significant (p > 0.2). Renal CMD can remain preserved on non-contrast T(1)-weighted or immediate Gd-SGE images in patients with acute presentation of ARF, independent of sCr level.

Focal liver lesions: comparison of dual-phase CT and multisequence multiplanar MR imaging including dynamic gadolinium enhancement

The purpose of this study was to compare dual-phase spiral computed tomography (CT) and magnetic resonance imaging (MRI) using dynamic gadolinium enhancement for liver lesion detection and characterization. Twenty-two consecutive patients underwent dual-phase spiral CT and MRI for the evaluation of focal liver disease within a 1-month period. Spiral CT and MR images were interpreted prospectively, in a blinded fashion by separate, individual, experienced investigators, to determine lesion detection and characterization. Liver lesions were confirmed by surgery and pathology in 6 patients, and by clinical and imaging follow-up in the other 16 patients. Pathological correlation of a primary extrahepatic malignancy was available in 5 of the 16 patients who had metastatic liver disease. Spiral CT and MRI detected 53 and 63 lesions, and characterized 39 and 62 true positive lesions, respectively. A kappa statistic test was applied to assess agreement between MR and CT results. MR versus CT for lesion detection resulted in a kappa statistic of 0.54 (95% confidence interval), indicating moderate agreement, and 0.32 (95% confidence interval) for lesion characterization, indicating only slight agreement. More lesions were detected on MR images than CT images in 6 (27%) patients, with lesions detected only on MR images in 4 (18%) patients. More lesions were characterized on MR images in 9 (41%) patients. In 9 patients with a discrepancy between MR and CT findings, the MR images added information considered significant to patient management in all 9 cases. MRI was moderately superior to dual-phase spiral CT for lesion detection, and was markedly superior for lesion characterization, with these differences having clinical significance.

Adrenal adenomas: characteristic postgadolinium capillary blush on dynamic MR imaging

We sought to evaluate dynamic post-gadolinium contrast enhanced magnetic resonance (MR) imaging characteristics of adrenal adenomas with comparison to those of malignant adrenal tumors. MR images, including in- and out-of-phase spoiled gradient echo (SGE) and dynamic gadolinium enhancement, of 35 adrenal adenomas in 34 patients, and 12 malignant adrenal tumors in 12 patients, were reviewed retrospectively. MR images were assessed for the presence of a capillary blush on immediate postgadolinium SGE images, and for rapid washout of contrast on 45-second postgadolinium SGE images. Thirty-five adrenal adenomas (mean size, 3.1 cm) and 12 malignant adrenal tumors (mean size, 7.4 cm) were assessed. Of 35 adrenal adenomas, 25 (71%) showed a homogeneous capillary blush on immediate postgadolinium images. Thirty-three (94%) adrenal adenomas demonstrated rapid washout on 45-second postgadolinium images (P < 0.001). Of 35 adrenal adenomas, 30 (86%) showed diminished signal intensity (SI) on out-of-phase images. Of 12 malignant adrenal tumors, none showed a homogeneous capillary blush on immediate postgadolinium images. Six (50%) malignant tumors showed negligible enhancement, four (33%) showed irregular patchy enhancement, and two (17%) showed peripheral enhancement (P < 0.001). On 45-second postgadolinium images, 11 (92%) of 12 malignant adrenal tumors showed irregular enhancement. In the majority of adrenal adenomas, an initial homogeneous capillary blush and rapid washout are demonstrated on gadolinium-enhanced dynamic MR imaging. Our preliminary results suggest that this may provide useful complementary information to the appearance of adrenal masses on in- and out-of-phase images.

MR imaging of pancreatic masses

MR imaging of the pancreas has evolved with better understanding of pathologic and radiologic correlation and with continued improvement in rapid-acquisition breath-hold or breathing-independent MR imaging techniques. MR imaging should be considered essential in the evaluation of pancreatic disease and particularly for optimal presurgical detection, characterization, and staging of pancreatic masses.

Inhibition of poly(ADP-ribose) polymerase attenuates ischemic renal injury in rats

The enzyme, poly(ADP-ribose) polymerase (PARP), effects repair of DNA after ischemia-reperfusion (I/R) injury to cells in nerve and muscle tissue. However, its activation in severely damaged cells can lead to ATP depletion and death. We show that PARP expression is enhanced in damaged renal proximal tubules beginning at 6-12 h after I/R injury. Intraperitoneal administration of PARP inhibitors, benzamide or 3-amino benzamide, after I/R injury accelerates the recovery of normal renal function, as assessed by monitoring the levels of plasma creatinine and blood urea nitrogen during 6 days postischemia. PARP inhibition leads to increased cell proliferation at 1 day postinjury as assessed by proliferating cell nuclear antigen and improves the histopathological appearance of kidneys examined at 7 days postinjury. Furthermore, inhibition of PARP increases levels of ATP measured at 24 h postischemia compared with those in vehicle-treated animals. Our data indicate that PARP activation is a part of the cascade of molecular events that occurs after I/R injury in the kidney. Although caution is advised, transient inhibition of PARP postischemia may constitute a novel therapy for acute renal failure.

Sequential use of gadolinium chelate and mangafodipir trisodium for the assessment of focal liver lesions: initial observations

The purpose of this study was to assess the feasibility of sequential administration of 2 different MR imaging contrast agents using a single visit protocol to image focal liver abnormalities. Twenty-one patients with known or suspected liver lesions were included in the study. All patients received a bolus intravenous injection of gadolinium chelate (Gd) and dynamically enhanced imaging performed. The patients then received an injection of mangafodipir trisodium (Mn) contrast and a second scan performed with an average delay of 62 min after the Gd bolus injection. The images were evaluated to determine the appearance of liver lesions after administration of each contrast agent, and for evidence of prior Gd administration adversely affecting evaluation of images acquired after Mn administration. Focal liver lesions were present in 19 patients, including 8 with liver metastases, 1 with liver lymphoma, 6 with hemangiomas, 3 with focal nodular hyperplasia (FNH), and 1 with hepatic abscess. In 2 other patients no liver lesions were identified in either the post-Gd or post-Gd-post-Mn scans. All malignant lesions identified on the post-Gd scan were also identified on post-Gd-post-Mn scans. Although the potential benefit for increasing detection sensitivity for hepatic metastases was not demonstrated, this is a preliminary series. This study does demonstrate the practicality for use a single visit sequential Gd-Mn protocol described here, with possible application of this technique for further assessment of the utility of combining Gd and Mn for detection of liver metastases.

Elevated blood pressure in men accompanying patients to the obstetrician's office

Hypertension is common and leads to increased mortality among adults; yet, one-third of hypertensive adults in the United States are unaware of their condition. The purpose of this study was to determine the frequency of unrecognized elevated blood pressure (BP) in men accompanying pregnant women to the obstetrician's office. Blood pressure measurements were offered to men accompanying pregnant women to four obstetrics practices in St. Louis, Missouri. Age, race, history of hypertension, and relationship to the pregnant woman were also recorded. A total of 191 men participated in the study. Participants' ages ranged from 15 to 69 years, with a mean of 27 years. Elevated BP (> 140/90 mm Hg) was detected in 40 men (21%). Only 5% of men with an elevated BP were aware of a prior history of elevated BP. We conclude that the obstetrician's office provides a good opportunity for initial screening for hypertension in men. Follow-up is necessary to determine the accuracy of the diagnosis.

Colon diseases: MR evaluation using combined T2-weighted single-shot echo train spin-echo and gadolinium-enhanced spoiled gradient-echo sequences

This study demonstrates the appearance of large bowel diseases on magnetic resonance (MR) images using breath-hold T2-weighted half-Fourier acquisition snapshot turbo spin-echo (HASTE), breath-hold T1-weighted spoiled gradient-echo (SGE), and breath-hold gadolinium-enhanced T1-weighted SGE with and without fat-suppression sequences. The study represents a collective experience using a generalized combined abdominal-pelvic imaging protocol. Of 29 patients, 27 had surgical, endoscopic, microbiological, and/or histopathological correlation, and 2 had a diagnosis based on characteristic imaging findings. Fifteen patients had neoplastic disease including colon adenocarcinoma (n = 11), rectosigmoid carcinoid (n = 1), familial adenomatous polyposis (n = 2), and cecal lipoma (n = 1). Fourteen patients had non-neoplastic disease including diverticulosis (n = 6), ischemic colitis (n = 2), pseudomembranous colitis (n = 2), acute appendicitis with periappendiceal abscess (n = 2), Mycobacterium avium intracellulare (MAI) colitis (n = 1), and Crohn's proctocolitis (n = 1). In all 15 patients with neoplastic diseases, MR imaging depicted the primary lesions and demonstrated local extent. Mass lesions were best shown on T2-weighted HASTE and gadolinium-enhanced fat-suppressed SGE images. Of 14 patients with non-neoplastic diseases, inflammatory changes were best shown on gadolinium-enhanced fat-suppressed T1-weighted SGE images in all cases. MR imaging with fast scanning breath-hold techniques and intravenous gadolinium enhancement provided good depiction and characterization of large bowel diseases.

Expression of CD44 in kidney after acute ischemic injury in rats

De novo CD44 and ligand expression at wound margins accompanies cellular proliferation and migration that effect repair of injured mucosal and vascular endothelial tissues. To determine whether CD44 could play a role in recovery from acute ischemic renal injury, we characterized its renal expression and those of two of its ligands, hyaluronic acid and osteopontin. Although no expression is detectable in nonischemic kidneys, several mRNAs for CD44 are present within 1 day after injury. CD44 mRNA is expressed in proximal tubules undergoing repair. CD44 peptide is present in basal and lateral cell membranes. Hyaluronic acid is normally expressed in the interstitium of the renal papilla only. By 1 day postischemia, hyaluronic acid can be detected, in addition, in the interstitium surrounding regenerating tubules. Osteopontin, not normally expressed in the renal proximal tubule, is expressed in regenerating tubules by 3 days after induction of acute ischemic injury. Immunoreactive osteopontin peptide continues to be localized in those tubules still undergoing repair for as long as 7 days after the injury. Our data are consistent with a role for CD44-ligand interactions in the regenerating proximal tubule participating in the process of recovery after ischemic injury.

SfbII protein, a fibronectin binding surface protein of group A streptococci, is a serum opacity factor with high serotype-specific apolipoproteinase activity

Serum opacity factor (SOF) is produced by group A streptococci belonging to certain M types. SOF cleaves the apolipoprotein component of the high density lipoprotein fraction of serum rendering it insoluble which in turn leads to serum opacity. SfbII protein, a fibronectin binding surface protein cloned from group A streptococci, was obtained from a strain of M75. Here we show that this protein has a second functional domain responsible for SOF activity. The fibronectin binding region was located in the C-terminal end of the protein. Deletion analysis showed that the remainder of the protein was required for SOF activity. Sequence analysis of SfbII, when compared with the published sequence of SOF22, showed 99% identity with a difference of only four amino acids. In spite of this high homology, SOF from M75 was type-specific and antibody evoked specifically inhibited only SOF produced by M75. Antibodies found in human serum following natural infection also inhibited the SOF of SfbII in a type-specific manner. The results showed that the SfbII protein from M75 is SOF with a high serotype-specific enzyme activity.

Spontaneous pyopneumopericardium

A previously healthy 42-year-old man presented to the emergency department with progressive weakness, lightheadedness, nausea, and lower extremity edema. Evaluation revealed hypotension, pulsus paradoxus, leukocytosis, hepatic and renal dysfunction, and an air-fluid level in the mediastinum. Emergency department ultrasound confirmed the presence of a large pericardial fluid collection. The patient was admitted to the medical intensive care unit with a diagnosis of pyopneumopericardium for emergent pericardiocentesis.

A significant increase in antimicrobial resistance among pneumococci causing invasive disease in New Zealand

AIMS

To review the prevalence of antibiotic resistance and the distribution of capsular types among pneumococci from invasive disease in New Zealand from 1995 through 1997.

METHOD

Pneumococci isolated from sterile sites that were referred to the Institute of Environmental Science and Research (ESR) were tested for antimicrobial susceptibility and capsular type.

RESULTS

A total of 994 pneumococci were referred by 27 hospital and community laboratories. Almost 74% of the isolates were from patients aged < 15 years or > or = 60 years. The majority (88.2%) of the isolates were from blood cultures. In 1997, cefotaxime-resistant pneumococci were confirmed for the first time from invasive disease in New Zealand. Over the three years, 6.0% of the pneumococci were penicillin-nonsusceptible (MIC > or = 0.12 mg/L) and 3.7% were cefotaxime-nonsusceptible (MIC > or = 1 mg/L). Penicillin nonsusceptibility increased significantly from 1.9% in 1995 to 6.2% in 1996 and 9.9% in 1997. Similarly, cefotaxime nonsusceptibility increased from 0.6% in 1995 to 3.5% in 1996 and 6.9% in 1997. In descending order of frequency, the ten most common capsular types were 14, 19, 6, 9, 1, 4, 18, 7, 23, and 3. Eighty-three percent of the penicillin-nonsusceptible pneumococci belonged to serotypes 9V, 19A, 19F, 23F, 14 and 6B and 90% belonged to serotypes included in the 23-valent vaccine.

CONCLUSIONS

The increasing prevalence of antimicrobial resistance among pneumococci highlights the need for continued surveillance and for effective measures to prevent pneumococcal infections.

An emergency department-based pneumococcal vaccination program could save money and lives

STUDY OBJECTIVE

Pneumococcal vaccination (PV) rates for eligible emergency department patients are less than 25%. This study determines the potential effect of an ED-based pneumococcal vaccination program in preventing pneumococcal bacteremia (PB) in high-risk patients.

METHODS

In a retrospective observational study, hospital records of 188 consecutive adults (>/=18 years old) with PB were reviewed to determine how many were treated in the ED from 1 to 72 months before their admission for bacteremia. Potential cost savings and mortality reductions from an ED-based PV program were calculated assuming PV prevents 65% of bacteremic episodes. A retrospective review of 10,650 ED charts determined the percentage of patients with PV indications and the relative frequency of indications.

RESULTS

One hundred four (55%) of the 188 patients with PB were seen in the ED less than or equal to 72 months before their admission for PB, and 91 (88%) of the 104 had indications for PV. These 91 patients had been evaluated in the ED an average of 3.4 times per patient during this 72-month period. Nine patients (10%) died before discharge. Mean hospital stay for the 82 survivors was 11.2 days. Of 10,650 ED charts reviewed, 2,011 (19%) had documented PV indications. Most prevalent PV indications were age 65 years or older (851 patients, 42%), diabetes mellitus (697, 35%), malignancy (248, 12%), chronic renal failure (228, 11%), and immunosuppression (221, 11%). Estimated cost savings ranged from $168,940 to $427,380.

CONCLUSION

ED-based PV programs would result in considerable cost savings and decreased mortality.

Percutaneous transluminal angioplasty of infrainguinal vessels

In the last decade, percutaneous angioplasty (PTA) has been used with increasing frequency to treat infrainguinal atherosclerotic lesions. In hopes of better delineating the role of PTA, we undertook a retrospective analysis of infrainguinal PTA in one hospital over a 7-year period. The charts of all patients receiving infrainguinal PTA from 1989 to 1996 were reviewed. Demographics, site and type of lesion, and results of treatment were recorded. Survival curves were plotted using the Kaplan-Meier method following current Society of Vascular Surgery/International Society for Cardiovascular Surgery (SVS/ISCVS) guidelines. Differences in times to first failure were tested using the log rank method. Failures were documented by duplex ultrasound. All patients requiring repeat intervention underwent contrast angiography. In selected patients with stenotic lesions <3 cm, infrainguinal PTA may be an appropriate initial treatment modality. However, 5-year patency rates are significantly lower than those achieved by saphenous vein grafting. The efficacy of the procedure is markedly decreased when used to treat arterial stenoses >3 cm in length as well as occlusions, and surgical revascularization may be a more appropriate initial therapeutic procedure.

Extracellular matrix-related genes in kidney after ischemic injury: potential role for TGF-beta in repair

The renal expression of transforming growth factor-beta1 (TGF-beta1) is enhanced following induction of ischemic injury in rat. In cultured renal cells, TGF-beta stimulates the synthesis of extracellular matrix. To link TGF-beta1 expression with the regulation of extracellular matrix postischemia, we characterized the expression of several genes known to regulate extracellular matrix synthesis at various times during recovery from acute ischemic renal injury in rat. Levels of mRNA for plasminogen activator inhibitor-1 (PAI-1), tissue inhibitor of metalloprotease-1 (TIMP-1), alpha1(IV) collagen, and fibronectin-EIIIA (FN-EIIIA) mRNAs were significantly enhanced in kidneys within 12 h to 3 days after injury and remained elevated at 7-28 days postischemia relative to levels in kidneys of sham-operated controls. PAI-1 mRNA and peptide were localized in regenerating proximal tubules at 3 and 7 days postischemic injury. alpha1(IV) Collagen and FN-EIIIA mRNAs were expressed primarily in regenerating proximal tubule cells. Immunoreactivity for FN-EIIIA was enhanced in the tubular basement membrane (TBM) of regenerating proximal tubules, and alpha1(IV) collagen immunoreactivity was detected in thickened tubulointerstitial spaces. In contrast, TIMP-1 immunoreactivity was enhanced in distal nephron structures postischemia. Immunoneutralization of TGF-beta in vivo attenuated the increases in FN-EIIIA, alpha1(IV) collagen, PAI-1, and TIMP-1 mRNAs by 52%, 73%, 43%, and 27%, respectively. These data are consistent with TGF-beta expression postischemic injury participating in renal regeneration of extracellular matrix homeostasis in the proximal TBM.

Quantitative evaluation of pork adulteration in raw ground beef by radial immunodiffusion and enzyme-linked immunosorbent assay

Quantitative estimates are important to establish whether pork adulteration in ground beef is accidental or intentional. A standard agar gel radial immunodiffusion (RID) test using forensic-grade antiserum to porcine albumin and an enzyme-linked immunosorbent assay (ELISA) using forensic-grade anti-porcine glycoprotein immunoglobulin were used to determine from 1 to 75% raw pork in raw ground beef. The RID test, which incorporated 1.5% anti-pork serum in 1% immunodiffusion agar, formed precipitin rings with pork albumin in agar wells. A linear standard curve was obtained by plotting the diffusion area against standard pork concentrations ranging from 0 to 80%. For the ELISA the endpoint optical density increased linearly versus log % pork between 0.0625% and 2% pork. In spiked samples, the RID test had a detection limit of 3 to 5%, a coefficient of variation (CV) of 22%, and a recovery of 105%. The ELISA had a detection limit of 1%, a CV of 18%, and a recovery of 114%. The mean recovery from the spiked samples by the ELISA and RID test was not significantly different (P > 0.05) from the known sample amounts. Quantitation by RID of 28 ground beef samples (27 of which were DTEK ELISA-positive for pork adulteration) revealed a wide range of pork content, with values as high as 48%.

Plasma leptin concentrations are only transiently increased in nephrectomized rats

Leptin is an adipocyte-secreted hormone that has effects on appetite and energy expenditure. Several studies have shown that end-stage renal disease results in elevated plasma leptin concentrations and that the kidney is responsible for most of leptin elimination in rodents. Leptin metabolism was investigated in rats that underwent unilateral nephrectomy to experimentally limit renal elimination function. Within 4 h of nephrectomy, plasma leptin concentrations increased from 2.9 +/- 0.8 to 5.8 +/- 1.0 & microg/l but thereafter rapidly (<24 h) decreased to prenephrectomy concentrations, despite continued elevated plasma creatinine levels. Sham-operated rats maintained presurgical concentrations of leptin and creatinine throughout the experiment. Kinetic studies of 125I-labeled leptin elimination showed that fractional catabolic rates and half-lives of leptin in circulation were similar at 48 h in nephrectomized and sham-operated rats, suggesting that production of leptin was unchanged after nephrectomy. Excretion of 125I derived from leptin in urine of nephrectomized rats was similar to that of sham-operated rats, and residual radioactivity was increased in the remaining kidneys excised from nephrectomized rats. These results demonstrate that 1) leptin concentrations are quickly restored to presurgical levels in nephrectomized rats, and 2) it is leptin elimination, not leptin production, that compensates to maintain leptin concentrations. Rapid metabolic adaptation of remaining renal tissue may explain the restoration of normal leptin elimination in nephrectomized rats.

Videotape increases parent knowledge about poliovirus vaccines and choices of polio vaccination schedules

OBJECTIVE

To study the effect of an educational videotape about poliovirus vaccines and choices of schedules for parents/guardians of children starting the polio vaccination series.

DESIGN

Prospective, randomized trial comparing two educational interventions.

SETTING

Five pediatric offices (two university-based, two health maintenance organization staff models, and one private practice) and a local health department immunization clinic in the greater Lansing, MI, area.

PARTICIPANTS

A total of 287 parents/guardians of 2- to 3-month-olds presenting for well-child care and due for the first set of immunizations including poliovirus vaccine.

INTERVENTIONS

Parents/guardians were randomized to read the vaccine information statement (VIS) alone or to read the VIS and view a 15-minute videotape about polio vaccination and choices of schedules produced by Michigan State University. The intervention groups were similar by race/ethnicity, education, and relationship to the child.

OUTCOME MEASURES

Change in knowledge about the risk of poliomyelitis in the United States, transmission of poliomyelitis, characteristics of the two poliovirus vaccines, and choices of polio vaccination schedules; and parent opinion on effectiveness of the interventions, as measured by pre- and postintervention questionnaires.

RESULTS

Both interventions resulted in increased test scores of knowledge. However, videotape viewers scored significantly higher on their posttest compared with parents/guardians assigned to VIS only. This significant increase was noted across all practice types, two of three major racial/ethnic groups, and educational levels. (The increase for Hispanic parents/guardians approached significance). Reading the VIS did not improve posttest scores for videotape viewers. Reading the VIS did improve posttest scores for those assigned to VIS only, but these scores still were not as high as for videotape viewers who did not read the VIS.

CONCLUSIONS

This study demonstrated that a complicated discussion of risks/benefits of two vaccines and their schedules of administration could be communicated effectively via a videotaped presentation. In addition, the videotape was more effective than VIS alone in increasing short-term knowledge, regardless of practice type, race/ethnicity, or educational level. As immunization schedules increase in complexity and parents are asked to make more choices, videotaped information may be a better method to achieve the goal of truly informed consent.

Group A streptococcal Vir types are M-protein gene (emm) sequence type specific

The M-protein genes (emm genes) of 103 separate impetiginous Streptococcus pyogenes isolates were sequenced and the sequence types were compared to the types obtained by Vir typing. Vir typing is based on restriction fragment length polymorphism (RFLP) analysis of a 4- to 7-kb pathogenicity island encoding emm and other virulence genes. By using both HaeIII and HinfI to generate RFLP profiles, complete concordance between Vir type and emm sequence type was found. Comparison of the emm sequences with those in GenBank revealed new sequence types sharing less than 90% identity with known types. Diversity in the emm sequence was generated by corrected frameshift mutations, point mutations, and small in-frame mutations.