Alterations in Lumbar Cerebrospinal Fluid Protein During Air Encephalography

A significant fall occurred in the protein content of successive specimens of lumbar cerebrospinal fluid (C.S.F.) withdrawn during the course of air encephalography in 57% of cases. No correlation was found between the fall in the protein concentration and the total volume of air injected or the total volume of C.S.F. withdrawn, but the size of the fall was greater when the initial lumbar C.S.F. protein concentration was raised. The importance of taking specimens for routine laboratory analysis before the injection of any air is emphasized.     

Structure-activity relationships of recombinant human interleukin 2

Structure-activity relationships of recombinant human interleukin 2 were investigated by preparation, purification, and characterization of 21 missense mutants. A key role for residue Phe42 in the high-affinity interaction with receptor was indicated by (a) the reduction of 5-10-fold in binding affinity and bioactivity upon mutation of this residue to Ala and (b) the lack of evidence for conformational perturbation in Phe42----Ala in comparison with the wild-type protein as investigated by intrinsic fluorescence, second-derivative UV spectroscopy, electrophoresis, and reversed-phase HPLC, suggesting that the drop in binding is a direct effect of removal of the aromatic ring. In contrast, the conservative mutations Phe42----Tyr and Phe42----Trp did not cause significant reductions in bioactivity. UV and fluorescence spectra indicated approximately 60% overall exposure to solvent of tyrosines in the wild-type molecule, the tryptophan (residue 121) being buried; fluorescence data also showed that Trp42 in Phe42----Trp is likely to be within 1 nm of Trp121 and about 50% exposed to solvent. Phe44----Ala, Cys105----Ala, and Trp121----Tyr also exhibited reduced bioactivity, but these mutants are conformationally perturbed relative to wild type. None of the remaining mutants had detectably reduced bioactivity, even though several showed signs of altered conformation. Four mutants were recovered in very low yield, probably because of defective refolding.     

Electron probe microanalysis of elemental composition of mouse cardiac myocytes during post-natal maturation

Elemental concentrations in the cytoplasm and nucleus of t tests post-natal mouse myocytes were measured at 2, 4, 8, 16, 32 days and in adults using electron probe X-ray microanalysis. Using an analysis of variance test, significant age dependent changes were found in intracellular potassium, sulfur, phosphorus, and chlorine concentrations (mg/kg dry weight), while sodium and magnesium concentrations did not show significant changes. The application of t tests following linear regression analyses (age versus concentration for each element) did, however, give a significant slope for cytoplasmic sodium, potassium, sulfur, and phosphorus values. The findings correspond closely with an emission spectroscopy-titrimetric study of whole heart ventricle of the same developmental period (Hazelwood and Nichols, '70).     

Differential genetic regulation of canine hip dysplasia and osteoarthritis

Background

Canine hip dysplasia (HD) is a common polygenic trait characterized by hip malformation that results in osteoarthritis (OA). The condition in dogs is very similar to developmental dysplasia of the human hip which also leads to OA.

Methodology/Principal Findings

A total of 721 dogs, including both an association and linkage population, were genotyped. The association population included 8 pure breeds (Labrador retriever, Greyhounds, German Shepherd, Newfoundland, Golden retriever, Rottweiler, Border Collie and Bernese Mountain Dog). The linkage population included Labrador retrievers, Greyhounds, and their crosses. Of these, 366 dogs were genotyped at ∼22,000 single nucleotide polymorphism (SNP) loci and a targeted screen across 8 chromosomes with ∼3,300 SNPs was performed on 551 dogs (196 dogs were common to both sets). A mixed linear model approach was used to perform an association study on this combined association and linkage population. The study identified 4 susceptibility SNPs associated with HD and 2 SNPs associated with hip OA.

Conclusion/Significance

The identified SNPs included those near known genes (PTPRD, PARD3B, and COL15A1) reported to be associated with, or expressed in, OA in humans. This suggested that the canine model could provide a unique opportunity to identify genes underlying natural HD and hip OA, which are common and debilitating conditions in both dogs and humans.     

Are We Heeding the Warning Signs? Examining Providers’ Overrides of Computerized Drug-Drug Interaction Alerts in Primary Care

Background

Health IT can play a major role in improving patient safety. Computerized physician order entry with decision support can alert providers to potential prescribing errors. However, too many alerts can result in providers ignoring and overriding clinically important ones.

Objective

To evaluate the appropriateness of providers’ drug-drug interaction (DDI) alert overrides, the reasons why they chose to override these alerts, and what actions they took as a consequence of the alert.

Design

A cross-sectional, observational study of DDI alerts generated over a three-year period between January 1st, 2009, and December 31st, 2011.

Setting

Primary care practices affiliated with two Harvard teaching hospitals. The DDI alerts were screened to minimize the number of clinically unimportant warnings.

Participants

A total of 24,849 DDI alerts were generated in the study period, with 40% accepted. The top 62 providers with the highest override rate were identified and eight overrides randomly selected for each (a total of 496 alert overrides for 438 patients, 3.3% of the sample).

Results

Overall, 68.2% (338/496) of the DDI alert overrides were considered appropriate. Among inappropriate overrides, the therapeutic combinations put patients at increased risk of several specific conditions including: serotonin syndrome (21.5%, n=34), cardiotoxicity (16.5%, n=26), or sharp falls in blood pressure or significant hypotension (28.5%, n=45). A small number of drugs and DDIs accounted for a disproportionate share of alert overrides. Of the 121 appropriate alert overrides where the provider indicated they would “monitor as recommended”, a detailed chart review revealed that only 35.5% (n=43) actually did. Providers sometimes reported that patients had already taken interacting medications together (15.7%, n=78), despite no evidence to confirm this.

Conclusions and Relevance

We found that providers continue to override important and useful alerts that are likely to cause serious patient injuries, even when relatively few false positive alerts are displayed.     

Quantification of acid-base interactions based on contact angle measurement allows XDLVO predictions to attachment of Campylobacter jejuni but not Salmonella

Acid-base (AB) interactions play the most important role in bacterial attachment to surfaces and can be quantified based on electron donor/electron acceptor data from contact angle measurement (CAM) according to the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. It follows that the XDLVO theory could fail to explain attachment numbers if differences in AB interactions between strains are not apparent by CAM. This study aimed to investigate the validity of the above assumptions by comparing empirical data on attachment of six bacterial strains (three strains of Campylobacter jejuni and three strains of Salmonella) to stainless steel and XDLVO theory predictions. A significant difference (P < 0.05) in AB interactions, apparent by CAM, between C. jejuni strains allowed prediction of attachment of this species by the XDLVO theory. However, the theory failed to explain the attachment numbers for Salmonella due to similar AB interactions, as established by CAM, between the three Salmonella strains. Qualitative analysis of AB interactions by microbial adhesion to solvents (MATS) revealed a significant difference (P < 0.05) in electron donor property between the three Salmonella strains suggesting that these strains may differ with respect to AB interactions. No significant correlation with respect to electron donor property (P = 0.502, r² = 12%) was apparent between CAM and MATS. These data suggest that CAM may not always reflect exactly AB interactions and that the difference in the outcomes from MATS and CAM should be considered when the XDLVO theory is used to predict bacterial attachment to surfaces.     

An alternative in vivo method to refine the mouse bioassay for botulinum toxin detection

Botulism is a rare, life-threatening paralytic disease of both humans and animals that is caused by botulinum neurotoxins (BoNT). Botulism is confirmed in the laboratory by the detection of BoNT in clinical specimens, contaminated foods, and cultures. Despite efforts to develop an in vitro method for botulinum toxin detection, the mouse bioassay remains the standard test for laboratory confirmation of this disease. In this study, we evaluated the use of a nonlethal mouse toe-spread reflex model to detect BoNT spiked into buffer, serum, and milk samples. Samples spiked with toxin serotype A and nontoxin control samples were injected into the left and right extensor digitorum longus muscles, respectively. Digital photographs at 0,8, and 24 h were used to obtain objective measurements through effective paralysis scores, which were determined by comparing the width-to-length ratio between right and left feet. Both objective measurements and clinical observation could accurately identify over 80% of animals injected with 1 LD(50) (4.3 pg) BoNT type A within 24 h. Half of animals injected with 0.5 LD(50) BoNT type A and none injected with 0.25 LD(50) demonstrated localized paralysis. Preincubating the toxin with antitoxin prevented the development of positive effective paralysis scores, demonstrating that (1) the effect was specific for BoNT and (2) identification of toxin serotype could be achieved by using this method. These results suggest that the mouse toe-spread reflex model may be a more humane alternative to the current mouse bioassay for laboratory investigations of botulism.