Random outcomes of allergen-specific responses in atopic families

BACKGROUND

Allergens are common non-infectious antigens to which people will mount T cell dependent humoral responses. Among genetically susceptible individuals, an antigen-specific response results involving the production of allergen-specific IgE (atopy).

OBJECTIVE

Determine if this susceptibility is manifested as an inherited, allergen-specific trait or a random response to allergens among susceptible people.

METHODS

We evaluated allergen-specific outcomes in 1099 members of families with positive atopic history (26 multi-generation and 112 nuclear families). Each was tested for sensitivity to 14 common allergens by standardized skin prick test (SPT), a marker of specific IgE production. Over 15,000 individual SPT's were evaluated. Among five randomly selected multi-generation families (N=163), semi-quantitative determinations of Amb a 1-specific IgA1,2 and IgG1-4 were determined in three groups: (A) Amb a SPT(+)/Amb a 1-IgE(+), (B) Amb a SPT(-)/Amb a 1-IgE(+), (C) Amb a SPT(-)/Amb a 1-IgE(-).

RESULTS

By rank correlation statistics, there were no discernible 'patterns' of specific SPT outcomes among any of the multi-generation families, suggesting that environmental exposure rather than allergen-specific inheritance determined the responses. This was confirmed among the nuclear families since the conditional SPT outcomes among children were independent of the SPT responses of their parents. Among five randomly selected multi-generation families, the relative proportionate concentrations of the Amb a 1-specific IgA and IgG subclasses were comparable, regardless of atopic sensitization to the ragweed allergen Amb a.

CONCLUSION

While the general propensity for atopy may be inherited, an individual's specific atopic outcome is a random variable independent of familial sensitization patterns.

Evidence that the mouse 3' kappa light chain enhancer confers position-independent transgene expression in T- and B-lineage cells

One of the major obstacles for successful application of murine leukemia virus (MLV) vectors to genetic therapy of lymphocyte disorders is low levels of transgene expression or the eventual loss of expression. To overcome this problem, an improved retroviral vector was constructed utilizing the myeloproliferative sarcoma virus (MPSV) long terminal repeat (LTR), which provided a significantly higher level of transgene expression in human lymphoid cells than did MLV vectors. Nevertheless, transgene expression remained low in a large percentage of transduced cells. To address whether lymphocyte enhancer elements might improve transgene expression mediated by retroviral vectors in lymphocytes, we cloned the mouse immunoglobulin 3' kappa light chain enhancer gene (mE3') into the MPSV vector. We found that the mE3' conferred a higher, more uniform and sustained level of expression in transduced T- and B-cell lines, and in primary T cells, than did the control vector lacking this element. Integration sites were diverse and a single copy of the proviral genome was present in all examined transduced cells. The mE3' failed to enhance transgene expression in most nonlymphoid cells, indicating it is relatively lineage-specific. Taken together, these results provide strong evidence that the mE3' functions as a locus control region (LCR) in conferring enhanced integration-site-independent expression of a retroviral transgene.

Binding and functional comparisons of two types of tumor necrosis factor antagonists

Two tumor necrosis factor (TNF) antagonists infliximab (a chimeric monoclonal antibody) and etanercept (a p75 TNF receptor/Fc fusion protein) have been approved for treatment of rheumatoid arthritis. However, these agents have shown different degrees of clinical benefit in controlled clinical trials in other TNF-mediated diseases such as Crohn's disease (CD) and psoriasis. We investigated whether structural differences between these two antagonists translate into different binding and functional characteristics. To study the binding of infliximab and etanercept to both the soluble and cell-surface transmembrane forms of TNF, a variety of in vitro binding and cell-based assays were performed. Binding assays using (125)I-labeled TNF showed that infliximab binds to both monomer and trimer forms of soluble TNF (sTNF), whereas etanercept binding is restricted to the trimer form. Infliximab formed stable complexes with sTNF, whereas etanercept formed relatively unstable complexes, resulting in release of dissociated TNF. KYM-1D4 cell killing assays and human umbilical vein endothelial cell activation assays demonstrated that TNF that had dissociated from etanercept was bioactive. Infliximab also formed more stable complexes with the transmembrane form of TNF expressed on transfected cells relative to analogous complexes formed with etanercept. Additionally, more infliximab molecules bound to the transmembrane TNF with higher avidity than etanercept. Although both infliximab and etanercept inhibited transmembrane TNF-mediated activation of human endothelial cells, infliximab was significantly more effective. The differences between infliximab and etanercept in their TNF binding characteristics may help explain their differential efficacy in CD and psoriasis clinical trials.

The use of an oral fluid immunoglobulin G ELISA for the detection of Helicobacter pylori infection in children

BACKGROUND

Enzyme linked immunosorbent assay (ELISA) evaluation of oral fluid immunoglobulin G (IgG) antibodies to Helicobacter pylori is a unique approach for both epidemiological studies and the diagnosis of infection, especially in children. The use of oral fluid sampling to evaluate specific H. pylori IgG antibodies has advantages over serum, including reduced biohazard risk and noninvasive collection. Oral fluid sampling is fast and involves minimal patient discomfort. Since children facilitate transmission of H. pylori infection, a simple, accurate, noninvasive diagnostic test is necessary for large epidemiologic studies. The aim of our study was to evaluate a new oral fluid ELISA for detection of IgG antibodies to H. pylori in children.

MATERIALS AND METHODS

We compared this new oral fluid ELISA with the HM-CAPTM serum ELISA and gastric biopsy histology using 779 oral fluid samples from children collected at 11 clinical sites across the United States. This cohort included 315 children symptomatic for abdominal pain and 464 asymptomatic. All samples were evaluated in a double blind manner. The oral fluid ELISA demonstrated a sensitivity of 76.2% and a specificity of 94.0% in children 2 months old to 201/2 years, as compared with the HM-CAPTM serologic assay. The assay's sensitivity improved to 81.3% in children aged 5 or greater and the specificity remained at 94.0%. When compared with gastric biopsy histology in the same age group, the oral fluid ELISA demonstrated a sensitivity of 71.7% and a specificity of 90.4%.

RESULTS

This new oral fluid ELISA is moderately sensitive and offers a very specific method for detecting H. pylori infection in older children, but it is of little value in children under the age of 5 years.

CONCLUSIONS

Overall, we conclude that this oral fluid ELISA does not appear to be a helpful clinical tool for the diagnosis of H. pylori infection in children.

Effects of 2 different anti-tumor necrosis factor-alpha agents in a primate model of subcutaneous abscess formation

Tumor necrosis factor (TNF)-alpha exerts both physiologic and pathologic effects in response to infection, conferring the benefit of host defense against infection at the risk of eliciting severe pathology if the response is excessive or inappropriate. In the present study, the effects of an anti-TNF-alpha monoclonal antibody (MAb) and a TNF-alpha receptor construct (p75-Fc) were compared with that of saline in a primate model of subcutaneous abscess induced with Staphylococcus aureus. Intravenous administration of anti-TNF-alpha MAb delayed the onset and reduced the incidence and the severity of abscess formation in response to inoculation with S. aureus at concentrations of 10(9) and 10(10) cfu/mL, compared with administration of saline. In contrast, no improvement in abscess formation was observed in animals treated with p75-Fc. These results supply initial evidence that anti-TNF-alpha MAb, unlike p75-Fc, provides a beneficial effect in this abscess model.

Anti-TNF-alpha antibody allows healing of joint damage in polyarthritic transgenic mice

Anti-tumor-necrosis-factor-alpha (TNF-alpha) monoclonal antibody was used to treat Tg197 transgenic mice, which constitutively produce human TNF-alpha (hTNF-alpha) and develop a progressive polyarthritic disease. Treatment of both young (7- or 8-week-old) and aged (27- or 28-week-old) mice commenced when at least two limbs showed signs of moderate to severe arthritis. The therapeutic efficacy of anti-TNF-alpha antibody was assessed using various pathological indicators of disease progression. The clinical severity of arthritis in Tg197 mice was significantly reduced after anti-TNF-alpha treatment in comparison with saline-treated mice and in comparison with baseline assessments in both young and aged mice. The treatment with anti-TNF-alpha prevented loss of body weight. Inflammatory pathways as reflected by elevated circulating hTNF-alpha and local expression of various proinflammatory mediators were all diminished by anti-TNF-alpha treatment, confirming a critical role of hTNF-alpha in this model of progressive polyarthritis. More importantly, the amelioration of the disease was associated with reversal of existing structural damage, including synovitis and periosteal bone erosions evident on histology. Repair of cartilage was age dependent: reversal of cartilage degradation after anti-TNF-alpha treatment was observed in young mice but not in aged mice.

Evidence of an affinity threshold for IgE-allergen binding in the percutaneous skin test reaction

BACKGROUND

Atopy is an aberrant immune response involving allergen-specific IgE production, though serum IgE concentration is not an entirely reliable diagnostic tool, particularly for epidemiological and genetic studies. There is no clear correlation between IgE and other indicators of atopy such as skin prick tests (SPT)s, and physiological associations are difficult to justify in cases with detectable IgE but negative SPT results.

OBJECTIVE

IgE reflects the number of molecules available to produce an atopic response, but the degree of the response is determined by the binding strength (affinity) between receptor-bound IgE and the allergen. We sought to determine if there was an association between binding affinity and SPT results in people with histories of atopy.

METHODS

Standard SPTs (whole allergen extracts) were administered to people with histories of sensitivities to ragweed and house dust mite. The concentrations and affinities of serum allergen-specific IgEs were determined using the purified allergens Amb a 1 and Der p 1.

RESULTS

There was a positive correlation between weal area and allergen-specific IgE among SPT-positive donors. However, for those individuals with detectable amounts of allergen-specific IgE, there was considerable overlap of IgE values between SPT-positive and -negative groups. Among sensitized donors, IgE-allergen interactions were characterized by two or three specific reactions of very high affinity (K(A) range 10(8) -10(11) M). Negative SPT reactions were associated with lowered IgE binding affinities to major allergens. This delimited two groups with atopic disorders: specific IgE(+)/ SPT(+) and specific IgE(+)/SPT(-).

CONCLUSION

The product of antibody affinity and concentration, which we define as antibody capacity (CAP = K(A) x IgE), is more informative with regard to describing allergen sensitivity than antibody concentration alone. Antibody binding capacity provides physiological evidence of atopy in some subjects who do not test positively by common methods and suggests an affinity threshold to produce a positive SPT reaction.

The outbreak of West Nile virus infection in the New York City area in 1999

BACKGROUND

In late August 1999, an unusual cluster of cases of meningoencephalitis associated with muscle weakness was reported to the New York City Department of Health. The initial epidemiologic and environmental investigations suggested an arboviral cause.

METHODS

Active surveillance was implemented to identify patients hospitalized with viral encephalitis and meningitis. Cerebrospinal fluid, serum, and tissue specimens from patients with suspected cases underwent serologic and viral testing for evidence of arboviral infection.

RESULTS

Outbreak surveillance identified 59 patients who were hospitalized with West Nile virus infection in the New York City area during August and September of 1999. The median age of these patients was 71 years (range, 5 to 95). The overall attack rate of clinical West Nile virus infection was at least 6.5 cases per million population, and it increased sharply with age. Most of the patients (63 percent) had clinical signs of encephalitis; seven patients died (12 percent). Muscle weakness was documented in 27 percent of the patients and flaccid paralysis in 10 percent; in all of the latter, nerve conduction studies indicated an axonal polyneuropathy in 14 percent. An age of 75 years or older was an independent risk factor for death (relative risk adjusted for the presence or absence of diabetes mellitus, 8.5; 95 percent confidence interval, 1.2 to 59.1), as was the presence of diabetes mellitus (age-adjusted relative risk, 5.1; 95 percent confidence interval, 1.5 to 17.3).

CONCLUSIONS

This outbreak of West Nile meningoencephalitis in the New York City metropolitan area represents the first time this virus has been detected in the Western Hemisphere. Given the subsequent rapid spread of the virus, physicians along the eastern seaboard of the United States should consider West Nile virus infection in the differential diagnosis of encephalitis and viral meningitis during the summer months, especially in older patients and in those with muscle weakness.

Echocardiographic outcome of infants treated as newborns with inhaled nitric oxide for severe hypoxemic respiratory failure

OBJECTIVE

To determine the cardiovascular outcome of a group of term newborns treated with inhaled nitric oxide (iNO) for severe hypoxemic respiratory failure with associated persistent pulmonary hypertension.

STUDY DESIGN

We performed echocardiographic evaluations in 40 survivors treated for severe neonatal hypoxemic respiratory failure. Each of the 40 had at least 2 follow-up echocardiograms at 3 or 6 and 24 months. These studies were compared with echocardiograms done in infants in a normal, age-matched control group.

RESULTS

Three of 31 infants met echocardiographic criteria for pulmonary hypertension at the 3-month examination. Two of the 3 had associated structural heart disease (1 with an atrial septal defect and 1 with a ventricular septal defect). At 24 months only 1 patient had pulmonary hypertension. This infant had an atrial septal defect that was surgically closed shortly after the 24-month echocardiogram because of the pulmonary hypertension. Group comparisons of 3- and 24-month echocardiographic variables showed no differences between the study and control groups. In the 31 infants in whom serial studies were completed, expected age-related changes were demonstrated between the 3- and 24-month examinations.

CONCLUSIONS

The incidence of residual pulmonary hypertension in infants treated as newborns for severe hypoxemic respiratory failure is low. The group at highest risk is those with structural heart disease.

Prevalence of ocular hemorrhage in patients receiving warfarin therapy

BACKGROUND

Warfarin, the drug most commonly used for outpatient anticoagulation therapy, has bleeding as its main side effect. The objective of this study was to determine the prevalence of ocular hemorrhage in patients receiving warfarin and to compare it to the prevalence in the general population.

METHODS

Patients receiving warfarin therapy who were attending the anticoagulation clinic at a tertiary care hospital in Montreal between October and December 1996 received a flyer inviting them to have their eyes examined to look for "ocular bleeding." Consenting patients were examined for subconjunctival hemorrhage, gross hyphema, and vitreous and retinal hemorrhages through external ocular examination and funduscopic examination with the pupils dilated using direct and indirect ophthalmoscopy.

RESULTS

Of the 1225 patients seen at the clinic 126 (10%) agreed to participate. Four patients (3%) were found to have intraretinal hemorrhage at the time of examination. All hemorrhages were visually insignificant.

INTERPRETATION

The risk of retinal hemorrhage in patients without preexisting ocular disease, such as retinal neovascularization or choroidal vasculopathy, who are receiving warfarin therapy is so small that it should not deter physicians from prescribing this drug when indicated.

Characterization of polyclonal allergen-specific IgE responses by affinity distributions

Polyclonal IgE responses have been previously characterized by allergen-specific antibody levels and by identification of amino acid sequences related to immunodominant epitopes. However, the binding affinities related to these antibody families are not well known. Using sera from donors with known sensitivities to ragweed or house dust mite allergens, we studied the binding reactions between the purified allergens Amb a 1 and Der p 1 and allergen-specific IgE's by determining affinity distribution functions. The distributions of binding affinities only exhibited a few dominant reactions indicated by peaks in an affinity distribution display. In all the donors tested, there were two dominant peaks and in 2/3 of the cases there was a third peak for both Amb a 1 and Der p 1. We further characterized the polyclonal interactions between IgE and Der p 1 by inhibiting the specific binding of IgE using peptide fragments known to be constituents of Der p 1 epitopes. Each peptide inhibited only a single peak in the affinity distributions. It would appear that the peaks in the affinity distribution represent antibodies directed to single epitopes. These results suggest that in our atopic population the response is surprisingly uniform. The bulk of the IgE response (70-80%) is of high affinity (10(8)-10(11) M(-1)) and directed towards a few epitopes. The relative affinities towards epitopes seem to be determined by the structure of the epitope and not variations of individuals' immune responses.

Optical filters consisting of metallic waveguide arrays

We demonstrate high-pass optical filters with cutoffs in the 0.3-10-micron spectral region. These filters consist of uniform arrays of hollow metallic waveguides, obtained by coating wafers of the previously developed channel-glass (CG) materials with a thin metal film. In these filters the channel diameter controls the cutoff frequency, the channel length controls the sharpness of the cutoff, and the channel density determines the transmission efficiency at cutoff. All of these parameters can be controlled in the CG starting material. The properties of the metal coatings that influence the filter properties are also discussed. Cutoff wavelengths near 300 nm have been achieved to date by using CG materials with submicrometer channel diameters. At all channel diameters, the transmission spectra include a peak just above the cutoff wavelength, where the transmission value can exceed that expected on the basis of the geometrical open area of the CG structure.

Seasonal changes in lung function in a farming population

OBJECTIVE

To assess the changes in respiratory health from winter to summer seasons in a rural population.

DESIGN

A longitudinal design was used in the study.

SETTING

A population-based study was conducted as part of the Environmental Pesticide Exposure and Human Health component of the Prairie Ecosystem Study (PECOS) in southwestern Saskatchewan.

PATIENTS

In the winter season, 358 patients participated in the study. Of these patients, 234 returned for the second assessment during the summer season. After excluding 34 children aged 17 years and under, 200 adult patients were available for analysis.

MEASUREMENTS

Questionnaires were used to obtain information on demographic factors, smoking habits, occupational and environmental exposures, and respiratory conditions. Pulmonary function measurements were obtained using a volume displacement spirometer.

RESULTS

Mean ages (+/- SD) of the 106 men and 94 women participating in the study were 50.1+/-13.3 and 49.0+/-13.1 years, respectively. Mean percentage changes in maximal midexpiratory flow rate from winter to summer assessments indicated an improvement for town residents and a decline for farm residents. Mean percentage changes in the ratio of forced expiratory volume in 1 s to forced vital capacity indicated an improvement for town residents who were not engaged in farming, and increasing declines for town residents engaged in farming, farm residents not engaged in farming and farm residents engaged in farming.

CONCLUSIONS

Seasonal changes occurred in measurements of pulmonary function between winter and summer seasons; these changes may be related to the environmental or occupational exposures experienced by the participants during the study.

Roscovitine, a specific inhibitor of cellular cyclin-dependent kinases, inhibits herpes simplex virus DNA synthesis in the presence of viral early proteins

We have previously shown that two inhibitors specific for cellular cyclin-dependent kinases (cdks), Roscovitine (Rosco) and Olomoucine (Olo), block the replication of herpes simplex virus (HSV). Based on these results, we demonstrated that HSV replication requires cellular cdks that are sensitive to these drugs (L. M. Schang, J. Phillips, and P. A. Schaffer. J. Virol. 72:5626-5637, 1998). We further established that at least two distinct steps in the viral replication cycle require cdks: transcription of immediate-early (IE) genes and transcription of early (E) genes (L. M. Schang, A. Rosenberg, and P. A. Schaffer, J. Virol. 73:2161-2172, 1999). Since Rosco inhibits HSV replication efficiently even when added to infected cells at 6 h postinfection, we postulated that cdks may also be required for viral functions that occur after E gene expression. In the study presented herein, we tested this hypothesis directly by measuring the efficiency of viral replication, viral DNA synthesis, and expression of several viral genes during infections in which Rosco was added after E proteins had already been synthesized. Rosco inhibited HSV replication, and specifically viral DNA synthesis, when the drug was added at the time of release from a 12-h phosphonoacetic acid (PAA)-induced block in viral DNA synthesis. Inhibition of DNA synthesis was not a consequence of inhibition of expression of IE or E genes in that Rosco had no effect on steady-state levels of two E transcripts under the same conditions in which it inhibited viral DNA synthesis. Moreover, viral DNA synthesis was inhibited by Rosco even in the absence of protein synthesis. In a second series of experiments, the replication of four HSV mutants harboring temperature-sensitive mutations in genes essential for viral DNA replication was inhibited when Rosco was added at the time of shift-down from the nonpermissive to the permissive temperature. Viral DNA synthesis was inhibited by Rosco under these conditions, whereas expression of viral E genes was not affected. We conclude that cellular Rosco-sensitive cdks are required for replication of viral DNA in the presence of viral E proteins. This requirement may indicate that HSV DNA synthesis is functionally linked to transcription, which requires cdks, or that both viral transcription and DNA replication, independently, require viral or cellular factors activated by Rosco-sensitive cdks.

Altered allergen binding capacities of Amb a 1-specific IgE and IgG4 from ragweed-sensitive patients receiving immunotherapy

BACKGROUND

The mechanisms for the effectiveness of allergen immunotherapy (IT) are not well understood. The binding potential for immunoglobulins is a function of both antibody concentration and affinity (K(A)).

PURPOSE

The purpose was to perform a cross-sectional preliminary study to investigate any differences in allergen-specific antibody affinity and concentration following ragweed immunotherapy by introducing a new concept of antibody binding capacity ([Ig] X K(A)).

METHODS

The binding capacity of allergen-specific IgE and IgG4 was determined for ragweed-allergic individuals undergoing ragweed immunotherapy and compared with the capacity of ragweed-specific IgE and IgG4 for allergic individuals not receiving immunotherapy.

RESULTS

The mean binding capacity for IgG4 after long-term immunotherapy was 1.6 log units higher (P < .0001) than for individuals not receiving IT. The binding capacity for allergen-specific IgE was 1.2 log units lower following long-term immunotherapy (P < .0001) compared with individuals not receiving ragweed IT.

CONCLUSIONS

We hypothesize that a primary effect of immunotherapy is to increase IgG4 binding capacity and concomitantly decrease IgE binding capacity.

Chronic recurrent multifocal osteomyelitis associated with chronic inflammatory bowel disease in children

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare disease of children characterized by aseptic inflammation of the long bones and clavicles. No infectious etiology has been identified, and CRMO has been associated with a number of autoimmune diseases (including Wegener's granulomatosis and psoriasis). The relationship between CRMO and inflammatory bowel disease is poorly described. Through an internet bulletin board subscribed to by 500 pediatric gastroenterologists, we identified six inflammatory bowel disease patients (two with ulcerative colitis, four with Crohn's colitis) with confirmed CRMO. In all cases, onset of the bony lesions preceded the onset of bowel symptoms by as much as five years. Immunosuppressive therapy for the bowel disease generally resulted in improvement of the bone inflammation. Chronic recurrent multifocal osteomyelitis should be considered in any inflammatory bowel disease patient with unexplained bone pain or areas of uptake on bone scan. CRMO may be a rare extraintestinal manifestation of inflammatory bowel disease; alternatively, certain individuals may be genetically predisposed to the development of both diseases.

The natural course of an ossifying fibroma. A case report

A patient with an ossifying fibroma in the mandible is presented, with a follow-up period of 38 years. The pathological findings and recommendations for therapy are discussed.

Elevated creatinine after ingestion of model aviation fuel: interference with the Jaffe reaction by nitromethane

A 2 years 9 month-old-boy who ingested model aviation fuel was found to have an elevated serum creatinine concentration of 0.53 mmol/L (normal range 0.02-0.05 mmol/L) by the Jaffe (alkaline picrate) reaction. However, when the creatinine concentration was measured using a specific enzymatic assay, it was within the normal range. It was shown that nitromethane, a constituent of aviation fuel, interferes with the Jaffe reaction, leading to a falsely elevated creatinine reading. This phenomenon has been reported only once previously and, despite its potential clinical importance, nitromethane does not appear in published lists of substances that interfere with the Jaffe reaction.

Coadministration of phenytoin and felbamate: evidence of additional phenytoin dose-reduction requirements based on pharmacokinetics and tolerability with increasing doses of felbamate

PURPOSE

This open-label study investigated the pharmacokinetic interaction of phenytoin (PHT) and felbamate (FBM).

METHODS

Ten subjects with epilepsy receiving PHT monotherapy were administered increasing doses of FBM (1,200, 1,800, 2,400-3,600 mg/day) at 2-week intervals. PHT doses were reduced by 20% on an individual basis when evidence of clinically significant intolerance was present. With intolerance, the PHT dose was reduced before the next incremental FBM dose. Blood samples were analyzed for FBM, PHT, and PHT metabolite 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH).

RESULTS

Total PHT plasma concentrations increased with coadministered FBM. PHT Cmax increased from 15.9 microg/ml at baseline to 20.9 microg/ml after 1,200 mg/day FBM and to 26.8 microg/ml after 1,800 mg/day FBM. Four subjects required a 20% PHT dose reduction after 1,800 mg/day FBM and six after the administration of 2,400 mg/day FBM. All subjects required further 20% PHT reductions before 3,600 mg/day FBM. FBM Cmax and AUCT were reduced, and apparent clearance increased compared with data from FBM monotherapy.

CONCLUSIONS

With the initiation of FBM therapy in subjects receiving PHT, the PHT dosage should be reduced by 20%. Further PHT dose reductions are likely to be necessary if the FBM dose is increased. The requirements for reductions in dose might be predicted by clinical signs of PHT intolerance.

Lysosphingomyelin prevents behavioral aberrations and hippocampal neuron loss induced by the metabotropic glutamate receptor agonist quisqualate

1. Excessive excitation of brain neurons by the excitatory neurotransmitter, glutamate, induces a cascade of events leading to increased intracellular Ca++, neuronal degeneration and death. 2. Recent in vitro research has demonstrated that a natural cationic amphiphile in the brain, lysosphingomyelin, may be able to prevent neuronal degeneration by repressing phosphosinositidase-C overactivation induced by excessive excitation of the metabotropic glutamate receptor. 3. This research tested the latter finding in vivo in a rat model of glutamate excitotoxicity. Intracerebroventricular (i.c.v.) administration of the Group 1 metabotropic glutamate receptor (mGluR) agonist, quisqualate, produced seizures, akinesia, destruction of hippocampal pyramidal cell dendritic microtubule-associated protein-2, and major loss of hippocampal CA sector neurons. 4. Prophylactic i.c.v. infusion of lysosphingomyelin powerfully attenuates these quisqualate-induced behaviors and prevents neuronal degeneration. 5. Lysosphingomyelin may be of clinical use in allaying progressive Group 1 mGluR-induced hippocampal cognitive and motor disorders including Alzheimer's disease, brain seizure, and stroke.

Expression of IgH chain genes in antibody response to ragweed and purified Amb a 1: evidence for differential regulation of isotype production

A survey of the work with Ig response to allergens carried out previously reveals an allergen-specific response both by IgE and all of IgG subclasses. Response of non-sensitive people is characterized by the appearance of a variety of the IgG subclasses. We have reexamined ragweed and Amb a 1 specific Ig response in 54 nonsensitive and 147 atopic or atopic-allergic people using a new inverse sandwich immunoassay allowing discrimination based on antibody affinity. We show that non-sensitive people present no, 0 out of 54, Ig response with affinities higher than Ka 10(7) M(-1). The subpopulation of 66 atopics who never have experienced desensitization responds vigorously and solely (56 out of 66) with genes of the sequence gamma2-alpha2. Only ten showed an additional weak response from gamma1-alpha1. This suggests a possible association between the atopic state and selective activation of part of the gene sequence.

Polyethylene wear debris and tissue reactions in knee as compared to hip replacement prostheses

Differences in bearing surface conformity and wear mechanisms suggest that the polyethylene (PE) wear debris generated by total knee replacement (TKR) prostheses should be different than that in total hip replacement prostheses (THR). To address this issue, PE wear debris and the cellular response in periprosthetic tissues from 19 failed TKRs was compared to that from 24 failed THRs using polarized light microscopy and a semiquantitative grading system. The foreign-body inflammatory reaction in the THR case was characterized by plump macrophages with a diffuse cytoplasmic birefringence when examined under polarized light, indicating the presence of multiple submicron particles of PE. The majority of PE particles were less than 1 mum in size and only a small fraction of the total were greater than 10 mum. The foreign-body inflammatory reaction in the TKR cases was characterized by giant cells with fewer macrophages. In the TKR specimens, the size range of PE particles was broader than in the hips. PE particles between 2 and 20 mum were frequent in TKR specimens; particles less than 1 mum in length were less common than in the THR specimens. Diffuse cytoplasmic birefringence was not a characteristic of the TKR cases. These histologic differences were so consistently distinct that the source of the specimen (i.e., from a THR or TKR) could be blindly determined by light microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Histologic identification of polyethylene wear debris using Oil Red O stain

Ultra high molecular weight polyethylene (UHMWPE) wear particles are frequently implicated in causing failure of total joint arthroplasties by eliciting a foreign body reaction. The majority of these particles are subcellular and many are submicron in size. Identification of these small particles of UHMWPE by conventional histologic techniques is difficult. We have therefore investigated the utility of Oil Red O (ORO) stain to identify UHMWPE on histologic sections. A wide variety of specimens was studied including an experimental rabbit model with subcutaneous implantation of polyethylene particles as well as specimens from clinical cases with joint arthroplasties. The sensitivity and specificity of ORO stain was compared to conventional polarized light microscopy for the identification of particulate UHMWPE debris. The ORO stain was found to be as sensitive in identifying particulate UHMWPE debris as polarized light microscopy. However, ORO stain was less specific: two specimens did not contain any UHMWPE also stained with ORO. Careful examination of standard hematoxylin and eosin stained sections with polarized light was therefore more specific for the identification of particulate UHMWPE. As a single test, the ORO stain does not appear to offer any clear advantage specifically for the identification of UHMWPE.

Transcription of herpes simplex virus immediate-early and early genes is inhibited by roscovitine, an inhibitor specific for cellular cyclin-dependent kinases

Although herpes simplex virus (HSV) replicates in noncycling as well as cycling cells, including terminally differentiated neurons, it has recently been shown that viral replication requires the activities of cellular cyclin-dependent kinases (cdks) (L. M. Schang, J. Phillips, and P. A. Schaffer, J. Virol. 72:5626-5637, 1998). Since we were unable to isolate HSV mutants resistant to two cdk inhibitors, Olomoucine and Roscovitine (Rosco), we hypothesized that cdks may be required for more than one viral function during HSV replication. In the experiments presented here, we tested this hypothesis by measuring the efficiency of (i) viral replication; (ii) expression of selected immediate-early (IE) (ICP0 and ICP4), early (E) (ICP8 and TK), and late (L) (gC) genes; and (iii) viral DNA synthesis in infected cultures to which Rosco was added after IE or IE and E proteins had already been synthesized. Rosco inhibited HSV replication, transcription of IE and E genes, and viral DNA synthesis when added at 1, 2, or 6 h postinfection or after release from a 6-h cycloheximide block. Transcription of a representative L gene, gC, was also inhibited by Rosco under all conditions examined. We conclude from these studies that cellular cdks are required for transcription of E as well as IE genes. In contrast, steady-state levels of at least one cellular housekeeping gene were not affected by Rosco. The requirement of viral IE and E transcription for cellular cdks may reflect either a requirement for specific cdk-activated cellular and/or viral transcription factors or a more global requirement for cdks in the transcriptional activation of the viral genome.

Psychosine blocks quisqualate-induced glutamate excitotoxicity in hippocampal CA sector neurons

Quisqualate is a potent specific agonist for Group 1 metabotropic glutamate receptors (mGluR's), that activate G protein-coupled phospholipase C (PLC) in a molecular signal-transduction mechanism that raises cytoplasmic Ca2+ and, when excessive, damages hippocampal neurons. Psychosine (beta-galactosylsphingosine), a cationic lysosphingolipid occurring naturally in nervous tissues, dose-dependently inhibited PLC activation induced by metabotropic alpha 1-adrenergic receptor signaling in cultured rat brain astrocytes in vitro. In the present study, we have tested neuroprotective efficacy of psychosine in vivo, in a rat model of glutamate excitotoxicity induced by intracerebroventricular (i.c.v.) administration of quisqualate. A sublethal i.c.v. dose of quisqualate caused episodes of prolonged akinesia and convulsions, and major damage to pyramidal neurons of the hippocampal CA1 and CA3 sector, but not to granule cell neurons of the dentate gyrus. Prior infusion of psychosine greatly attenuated quisqualate-induced behaviors, and fully prevented destruction by quisqualate of vulnerable hippocampal neurons. Psychosine may prove useful in prophylaxis of neurodegenerative disorders that arise from intensive hippocampal Group 1 mGluR stimulation.

Hemoglobinopathies affecting maternal-fetal oxygen gradient during pregnancy: molecular, biochemical and clinical studies

The higher oxygen (O2) affinity of fetal blood compared to maternal blood has been considered advantageous for the survival of the fetus. However, there is little information on infants born to mothers who carry a hemoglobin (Hb) variant with altered O2 affinity. This report describes two mothers and their newborn infants, each with a different globin chain variant are identified as Hb Linköping, [beta36(C2)Pro-->Thr] and Hb Sunshine Seth [alpha94(G1)Asp-->His]. Hb Linkoping is a known high O2 affinity variant, while Hb Sunshine Seth was found to have a low affinity for O2. One mother and her newborn, both with a heterozygosity for Hb Linköping, had P50 values of 1.9 and 2.5 kPa, respectively, a reversal of the physiological maternal-infant gradient. The other mother and her newborn, who were heterozygous for Hb Sunshine Seth, had P50 values of 4.7 and 4.4 kPa, respectively, a minimal gradient. The Hb F, plasma erythropoietin, and 2,3-diphosphoglycerate (2,3-DPG) levels were normal in both infants. The newborns were clinically normal.

Serotonin reuptake inhibitors and the adequacy of antidepressant treatment

OBJECTIVE

To determine whether the use of serotonin reuptake inhibitors (SSRIs) improves antidepressant medication prescribing patterns for both psychiatric and non-psychiatric physicians.

DATA SOURCES/SETTING

Drug utilization review of 4,103 prescriptions for antidepressant medications with patients diagnosed with depressive disorders over an eighteen-month period from the formulary records of a large insurance company.

DESIGN

Using standards developed for clinical guidelines, variation in trial and treatment adequacy between drug types and physician specialty was studied.

PRINCIPAL FINDINGS

Thirty-five percent of initial antidepressant trials were not prescribed for an adequate duration or at an adequate dosage level. SSRIs were more likely to be prescribed adequately than any other antidepressant reviewed. Psychiatrists were more likely to prescribe antidepressants at an adequate dosage level, whereas non-psychiatric physicians were more likely to attain adequate duration of treatment.

CONCLUSIONS

A greater reliance on SSRIs may increase the likelihood of maintaining adequacy in antidepressant treatments. Although higher in cost than other treatment choices, their lower side effect profile is likely to maximize patient satisfaction and physician and patient adherence to guidelines. In order to ensure effective and efficient antidepressant usage, such patterns must be identified and appropriate performance improvement strategies (e.g., Total Quality Improvement, critical pathways) may be employed.

An automated method for determination of antibody affinity distribution functions with nanogram quantities

We have developed a method to determine the binding affinity distribution functions (the probability density function for affinity constants will be referred to as affinity distribution throughout the text) for human serum antigen specific IgE for their respective allergens. This fully automated method, based on the Access technology of Sanofi Diagnostics Pasteur, is a highly sensitive two-step sandwich immunoassay requiring only nanogram quantities of antibodies. Allergen-antibody binding isotherms can be determined covering a range of 5 magnitudes of ligand (allergen) concentration. An affinity distribution function, describing the polyclonal nature of the antibody response, can be calculated from the binding isotherm. The validity of the method is assessed using mAbs against the purified allergen Der p 1. The resolving power and sensitivity of the method are demonstrated using selected sera from donors with high and low levels of specific IgE for these allergens. We are able to show that heterogeneous IgE populations can be determined using 100 microl of sera containing 150 pg of specific IgE per ml. Overall, the range of affinities that can be determined by this method is 1 x 10(6)-1 x 10(11) M(-1).

Evaluation of the potential interaction between felbamate and erythromycin in patients with epilepsy

Effects of erythromycin on hepatic CYP450 3A4 isozymes can profoundly influence the metabolism of many therapeutic agents. An open-label, randomized, two-period, crossover study was therefore conducted to evaluate the pharmacokinetics of felbamate before and after a concurrent 10-day regimen (333 mg three times daily) of erythromycin. Patients were receiving either 3,000 or 3,600 mg/day felbamate monotherapy for treatment of epilepsy. Mean dose-normalized values for maximum concentration (Cmax) and area under the concentration-time curve (AUC tau) of felbamate were not statistically different in patients taking felbamate as monotherapy than in patients after erythromycin coadministration. Estimates of time to Cmax (tmax), minimum concentration (Cmin), apparent clearance (Cl/kg), average concentration (Cav), and degree of fluctuation (DFss) were likewise unchanged. The incidence of mild and moderate adverse events increased during coadministration of the two drugs. Because patients with epilepsy can not be treated with erythromycin alone, it could not be determined whether the adverse events were attributable to erythromycin or to the combination of the two drugs. Steady-state pharmacokinetic parameters of felbamate were not influenced by erythromycin coadministration.

High-dose chemotherapy and peripheral blood stem cell infusion in patients with non-Hodgkin's lymphoma: results of outpatient treatment in community cancer centers

The outcomes for patients with non-Hodgkin's lymphoma (NHL) treated with high-dose chemotherapy (HDC) and peripheral blood stem cell (PBSC) infusion by practicing oncologists in community cancer centers in the United States were determined. Eighty-three patients with NHL, who had failed conventional chemotherapy, underwent mobilization of PBSC with chemotherapy and a recombinant growth factor in an outpatient facility. At a median of 40 days (range 26-119) after mobilization chemotherapy all received carmustine (300 mg/m2 x 1), etoposide (150 mg/m2 twice a day x 4 days), cytarabine (100 mg/m2 twice a day x 4 days) and cyclophosphamide (35 mg/kg x 4 days) (BEAC) followed by infusion of unmanipulated PBSC in an outpatient facility. The probabilities of treatment-related mortality, relapse/progression, overall survival (OS) and event-free survival (EFS) at 3 years for all 83 patients were 0.07, 0.57, 0.49 and 0.38, respectively. The probabilities of relapse/progression, OS and EFS at 3 years for 28 patients who had failed primary induction chemotherapy were 0.55, 0.42 and 0.38, respectively. The probabilities of OS and EFS for 27 patients in untreated first relapse were 0.52 and 0.44, respectively, as compared to 0.56 and 0.32, respectively, for 18 patients who had reinduction attempts prior to receiving mobilization chemotherapy (P = 0.81 for OS and 0.99 for EFS). No significant risk factors for the outcomes of TRM, relapse/progression, OS or EFS could be identified. These data demonstrate that approximately 40% of patients with NHL who have failed conventional chemotherapy become long-term disease-free survivors after mobilization chemotherapy, high-dose BEAC and PBSC infusion administered in an outpatient setting in community cancer centers, with the major cause of failure being relapse. Results obtained in this study are comparable to published data in similar patient populations receiving therapy as inpatients, suggesting that clinical trials involving well-tested HDC regimens can be carried out safely in this setting.

The cement mantle in femoral impaction allografting. A comparison of three systems from four centres

An analysis of the cement mantle obtained with the Exeter impaction allografting system at one centre showed that it was either deficient or absent in almost 47% of Gruen zones. We therefore examined the mantle obtained using this system at another hospital and compared the results with those from the CPT and Harris Precoat Systems at other centres. The surgical indications for the procedure and the patient details were broadly similar in all four hospitals. There was some variation in the frequency of use of cortical strut allografts, cerclage wires and wire mesh to supplement the impaction allograft. Analysis of the cement mantles showed that when uncertain Gruen zones were excluded, the incidence of zones with areas of absence or deficiency of the cement was 47% and 50%, respectively, for the two centres using the Exeter system, 21% for the CPT system and 18% for the Harris Precoat system. We measured the difference in size between the proximal allograft impactors and the definitive prosthesis for each system. The Exeter system impactors are shorter than the definitive prosthesis and taper sharply so that the cavity created is inadequate, especially distally. The CPT proximal impactors are considerably longer than the definitive prosthesis and are designed to give a mantle of approximately 2 mm medially and laterally and 1.5 mm anteriorly and posteriorly. The Harris Precoat proximal impactors allow for a mantle with a circumference of 0.75 mm in the smaller sizes and 1 mm in the larger. Many reports link the longevity of a cemented implant to the adequacy of the cement mantle. For this reason, femoral impaction systems require careful design to achieve a cement mantle which is uninterrupted in its length and adequate in its thickness. Our results suggest that some current systems require modification.

THE CEMENT MANTLE IN FEMORAL IMPACTION ALLOGRAFTING

An analysis of the cement mantle obtained with the Exeter impaction allografting system at one centre showed that it was either deficient or absent in almost 47% of Gruen zones. We therefore examined the mantle obtained using this system at another hospital and compared the results with those from the CPT and Harris Precoat Systems at other centres.

The surgical indications for the procedure and the patient details were broadly similar in all four hospitals. There was some variation in the frequency of use of cortical strut allografts, cerclage wires and wire mesh to supplement the impaction allograft. Analysis of the cement mantles showed that when uncertain Gruen zones were excluded, the incidence of zones with areas of absence or deficiency of the cement was 47% and 50%, respectively, for the two centres using the Exeter system, 21% for the CPT system and 18% for the Harris Precoat system.

We measured the difference in size between the proximal allograft impactors and the definitive prosthesis for each system. The Exeter system impactors are shorter than the definitive prosthesis and taper sharply so that the cavity created is inadequate, especially distally. The CPT proximal impactors are considerably longer than the definitive prosthesis and are designed to give a mantle of approximately 2 mm medially and laterally and 1.5 mm anteriorly and posteriorly. The Harris Precoat proximal impactors allow for a mantle with a circumference of 0.75 mm in the smaller sizes and 1 mm in the larger.

Many reports link the longevity of a cemented implant to the adequacy of the cement mantle. For this reason, femoral impaction systems require careful design to achieve a cement mantle which is uninterrupted in its length and adequate in its thickness. Our results suggest that some current systems require modification.

Lack of effect of azelastine and ketoconazole coadministration on electrocardiographic parameters in healthy volunteers

Azelastine, an antihistamine with additional pharmacologic properties, was evaluated for a possible influence on pharmacokinetic and electrocardiographic parameters due to its coadministration with CYP3A4 inhibitor ketoconazole (200 mg every 12 hrs). Twelve volunteers entered this three-period, open-label study. Electrocardiographic parameters (PR, QRS and QTc intervals and U-wave morphology) were monitored after 14 days of azelastine HCl (4.4 mg every 12 hrs), after 7 days of either azelastine/ketoconazole or azelastine/placebo, and after a 21-day washout period, which was then followed by a 7-day administration of ketoconazole alone. None of the treatments resulted in meaningful alterations of electrocardiographic variables. Pharmacokinetic parameters could not be estimated because ketoconazole metabolites interfered with azelastine assay procedures. In vitro tests with human liver microsomes were used to characterize azelastine's inhibition spectrum. Azelastine did not inhibit CYP3A4 activity but it did inhibit CYP2D6 and CYP2C19 activity with Ki values exceeding maximum plasma concentration by 120 to 800-fold. Therefore, in vitro tests and the absence of electrocardiographic effects suggests azelastine can be safely administered with CYP3A4 inhibitors.

B-cell epitopes recognized by IgE from patients sensitive to Amb a 5

BACKGROUND

The response to allergens characterized by IgE-mediated hypersensitivity is selective. The search for the inherited contribution to atopy has among other things, focused on the linkage of sensitivity to the presence of specific alleles in the DR and DQ locus. More than 90% of the responders to Amb a 5, an allergen from ambrosia artemisifolia, are DR-2 positive. This relationship is logically linked to the T-cell epitope presentation by the HLA complex.

OBJECTIVES

This study aims to investigate a possible relationship between T-cell epitopes, B-cell epitopes and the alleles of the DR and DQ loci in Amb a 5 sensitive DR-2+ and DR-2- individuals.

METHODS

Inhibition of solid state Elisa assays by IgE-enriched and IgG-depleted, heated sera. The inhibition was carried out in checkerboard pattern, bidirectionally; A inhibits B and B inhibits A.

RESULTS

The B-cell epitopes defined by the inhibition pattern were all found to be conformational. Three different epitope patterns (A, B, C) were recognized. The IgE and IgG complexes were found in only one responder. The DR and DQ locus alleles were all sequenced. Although all the individuals studied responding to Amb a 5 show presence of alleles such as 1501, associated with DR-2, our data indicates no correlation between the B-cell epitopes recognized and the DR and DQ locus alleles. A well known, general T-cell motif was recognized in the known sequence of Amb a 5.

CONCLUSIONS

Our investigation suggests that the choice of B-cell recognition is regulated independently of a putative link between T-cell epitope recognition and the D locus.

Prevention of deep-vein thrombosis after total hip arthroplasty. Comparison of warfarin and dalteparin

The effectiveness and safety of warfarin were compared with those of a low-molecular-weight heparin (dalteparin) for the prevention of deep-vein thrombosis after total hip arthroplasty in a prospective, randomized, multi-institutional trial. Patients who were older than eighteen years of age and were scheduled to have an elective primary or revision total hip arthroplasty were eligible; 580 patients were randomized, 550 had the operation and received prophylaxis, and 382 had evaluable venograms. Prophylaxis was provided either with warfarin beginning the night before the operation or with dalteparin beginning two hours before the operation and was continued until venography was performed. Bleeding was assessed on the basis of intraoperative blood loss, transfusion requirements, a decrease in hematocrit, and clinically identified bleeding complications. The prevalence of deep-vein thrombosis was found to be significantly lower in the patients who had received dalteparin than in those who had received warfarin (twenty-eight [15 per cent] of 192 patients compared with forty-nine [26 per cent] of 190 patients; p = 0.006). Deep-vein thrombosis occurred in the calf veins of twenty-one patients (11 per cent) who had received dalteparin and of forty-three patients (23 per cent) who had received warfarin; this difference was significant (p = 0.003). Proximal deep-vein thrombosis occurred in ten patients (5 per cent) who had received dalteparin and in sixteen patients (8 per cent) who had received warfarin; however, with the numbers available, no significant difference could be detected (p = 0.185). We also could not detect a significant difference with regard to the intraoperative and postoperative blood loss, the decrease in hematocrit, and the prevalence of major bleeding complications between the two groups; however, the patients who had received dalteparin had a significantly higher prevalence of bleeding complications involving the operative site (p = 0.03), and a significantly greater percentage required postoperative transfusions (p = 0.001). We concluded that preoperative prophylaxis with dalteparin is significantly more effective than that with warfarin in preventing deep-vein thrombosis after total hip arthroplasty. The greater effectiveness of dalteparin must be considered, however, in light of an increased need for postoperative transfusions and an increase in the prevalence of wound-related bleeding complications.

Tolerability and pharmacokinetics of monotherapy felbamate doses of 1,200-6,000 mg/day in subjects with epilepsy

PURPOSE

Felbamate (FBM) pharmacokinetic parameters, safety and tolerability in the dose range of 1,200-6,000 mg/day were assessed in two open-label studies with similar designs.

METHODS

In study A, newly diagnosed subjects with epilepsy receiving FBM monotherapy at a starting dose of 1,200 mg/day (400 mg/three times daily, t.i.d.) and increased 1,200 mg/day, if tolerated, at 14-day intervals to 3,600 mg/day were investigated. In study B, epilepsy subjects with prior FBM monotherapy exposure received ascending FBM doses in five consecutive 14-day periods with a starting dose of 3,600 mg/day (1,200 mg t.i.d.) FBM. In each successive period, if FBM was well tolerated, the dose was increased by 600 mg/day to a maximum of 6,000 mg/day (2,000 mg t.i.d.).

RESULTS

The pharmacokinetic parameter estimates maximum observed concentration (Cmax), area under the concentration-time curve (AUCtau) Ctrough, and Cav showed a linear dependence to dose above the 1,200-6,000 mg/day FBM dose range (F-tests; p < 0.0001) with apparent clearance (Cl/kg) and Tmax (time to Cmax) independent of dose. When AUCtau, Cmax and Ctrough were adjusted for dose, there were no significant differences between the dosing periods.

CONCLUSIONS

The data establish that plasma concentrations of FBM are linear with respect to dose to 6,000 mg/day. In addition, FBM was safely administered at these doses for periods as long as 14 days to epileptic subjects with prior exposure to FBM. FBM-naive subjects appeared to report more adverse experiences (generally of mild to moderate severity) than did subjects with prior FBM exposure.

Immediate coronary angiography in survivors of out-of-hospital cardiac arrest

BACKGROUND

The incidence of acute coronary-artery occlusion among patients with sudden cardiac arrest outside of the hospital is unknown, and the role of reperfusion therapy has not been determined. We therefore performed immediate coronary angiography and angioplasty when indicated in survivors of out-of-hospital cardiac arrest.

METHODS

Between September 1994 and August 1996, coronary angiography was performed in 84 consecutive patients between the ages of 30 and 75 years who had no obvious noncardiac cause of cardiac arrest.

RESULTS

Sixty of the 84 patients had clinically significant coronary disease on angiography, 40 of whom had coronary-artery occlusion (48 percent). Angioplasty was attempted in 37 patients and was technically successful in 28. Clinical and electrocardiographic findings, such as the occurrence of chest pain and the presence of ST-segment elevation, were poor predictors of acute coronary-artery occlusion. The in-hospital survival rate was 38 percent. Multivariate logistic-regression analysis revealed that successful angioplasty was an independent predictor of survival (odds ratio, 5.2; 95 percent confidence interval, 1.1 to 24.5; P=0.04).

CONCLUSIONS

Acute coronary-artery occlusion is frequent in survivors of out-of-hospital cardiac arrest and is predicted poorly by clinical and electrocardiographic findings. Accurate diagnosis by immediate coronary angiography can be followed in suitable candidates by coronary angioplasty, which seems to improve survival.

Patellofemoral design influences function following total knee arthroplasty

The functional influence of patellofemoral design was evaluated by testing two cohorts of patients with total knee arthroplasty while walking, climbing stairs, and rising from a chair. The two cohorts received one of two different designs of total knee arthroplasty. The designs differed primarily in the curvature of the femoral trochlea. These differences in curvature have been shown in in vitro studies to influence the tracking of the patella. One design had a smaller radius on the patellar flange, which caused the patella to articulate more anteriorly and distally than the second design, which had a larger radius in this region. The second design more closely replicated the curvature of the femoral trochlear anatomy. There was a significant functional difference during stairclimbing between the patient groups, whereas there was no difference during walking or chair rising. The group with the design that had nonanatomic tracking of the patella had a higher than normal moment tending to flex the knee (net quadriceps moment) during late stance phase. The increased net quadriceps moment during late stance was concurrent with an increased knee flexion. The abnormal function occurred when the patellar was tracking over the nonanatomic portion of the trochlea. Patients in the group with the anatomic trochlea did not have abnormal function. These results suggest a relationship between a nonanatomic trochlea and abnormal function during stair-climbing.

The affinity of allergen specific IgE and the competition between IgE and IgG for the allergen in Amb a V sensitive individuals

We have calibrated a solid state RAST assay with affinity purified allergen-specific IgE. We then utilized the calibrated assay to measure the average affinity of individual IgE-containing sera in terms of the average association constant < K > for purified allergen Amb a V. The binding data yielded linear reciprocal plots indicating that the range of affinities of the responding clones was narrow. The range of the average association constant for the IgE-Amb a V complex was 0.9-26 x 10(10) M-1. The average affinity of the corresponding IgG response in the same individual, estimated by inhibition studies of IgE binding, was 10(7) M-1 in one case and lower than 10(6) M-1 in all the other cases.