Hydration level monitoring using embedded piezoresistive microcantilever sensors

A new MEMS based sensor technology, embedded piezoresistive microcantilever (EPM) sensors, may be useful in the real-time monitoring of hydration levels in athletes or other individuals whose activities may result in dehydration. In these devices, organic polymers or functionalized polymeric materials respond to osmolality changes in a person's saliva by expanding or contracting volumetrically. These volumetric changes are measured by tiny piezoresistive microcantilevers embedded in the polymeric material. In this report, we have tested a prototype device utilizing UV crosslinked poly(vinyl acetate) as the active sensing material. This device was able to reliably respond to 1% changes in sodium chloride concentration in solution or alternately to 1% changes in relative humidity.

Nucleotide sequence, genome organization and phylogenetic analysis of Strawberry pallidosis associated virus, a new member of the genus Crinivirus

The complete nucleotide sequence of Strawberry pallidosis associated virus (SPaV), a newly identified member of the genus Crinivirus, family Closteroviridae has been determined. RNA 1 is 8067 nucleotides long and encodes at least three open reading frames (ORFs). The first ORF (ORF 1a) specifies a multifunctional protein that has papain-like proteinase, methyltransferase and RNA helicase domains. The RNA-dependent-RNA polymerase is encoded in ORF 1b and is probably expressed by a +1 ribosomal frameshift. The 3' ORF of RNA 1 encodes a small protein with two potential transmembrane helices. RNA 2 is 7979 nucleotides long and encodes 8 ORFs, similar in amino acid sequence and arrangement with those of other criniviruses. SPaV encodes the largest structural protein of closteroviruses sequenced to date as the minor coat protein of the virus has molecular mass of approximately 80 kDa. The 3' non-translated regions share nucleotide sequence identities of about 56% and the predicted folding of the non-translated regions is similar. Phylogenetic analyses reveal that SPaV is related most closely to Abutilon yellows virus and Beet pseudo-yellows virus, another virus that has been identified recently to cause identical symptoms on strawberry indicator plants as SPaV.

Reef-coral proteins as visual, non-destructive reporters for plant transformation

Recently, five novel fluorescent proteins have been isolated from non-bioluminescent species of reef-coral organisms and have been made available through ClonTech. They are AmCyan, AsRed, DsRed, ZsGreen and ZsYellow. These proteins are valuable as reporters for transformation because they do not require a substrate or external co-factor to emit fluorescence and can be tested in vivo without destruction of the tissue under study. We have evaluated them in a large range of plants, both monocots and dicots, and our results indicate that they are valuable reporting tools for transformation in a wide variety of crops. We report here their successful expression in wheat, maize, barley, rice, banana, onion, soybean, cotton, tobacco, potato and tomato. Transient expression could be observed as early as 24 h after DNA delivery in some cases, allowing for very clear visualization of individually transformed cells. Stable transgenic events were generated, using mannose, kanamycin or hygromycin selection. Transgenic plants were phenotypically normal, showing a wide range of fluorescence levels, and were fertile. Expression of AmCyan, ZsGreen and AsRed was visible in maize T1 seeds, allowing visual segregation to more than 99% accuracy. The excitation and emission wavelengths of some of these proteins are significantly different; the difference is enough for the simultaneous visualization of cells transformed with more than one of the fluorescent proteins. These proteins will become useful tools for transformation optimization and other studies. The wide variety of plants successfully tested demonstrates that these proteins will potentially find broad use in plant biology.

Splenic injury after intraoperative transesophageal echocardiography

A 55-year-old woman underwent coronary artery bypass grafting and mitral valve repair using intraoperative transesophageal echocardiography (TEE). Postoperatively she had hemodynamic instability associated with an increase in abdominal size and a drop in hemoglobin. At laparotomy, a splenic hilar laceration was discovered, which was presumed to be associated with intraoperative TEE. She underwent emergent splenectomy. This case demonstrates that although rare, serious complications can occur with TEE.

A medical perspective on the adventures of Sherlock Holmes

The adventures of Sherlock Holmes, although primarily famous as stories of detection of crime, offer a considerable amount to interest the medical reader. There are many medical references in the stories, and the influence of Conan Doyle's medical background is clearly seen in the main characters. Aspects of the stories also reflect Conan Doyle's medical career, and also something of his attitude towards the profession. From Holmes's sayings and accounts of his methods, parallels can be drawn between Holmesian deduction and the diagnostic process. It is concluded, however, that deduction cannot be used as a direct paradigm since medical problems are rarely soluble through a process of logic alone.

Revisiting the short cervix detected by transvaginal ultrasound in the second trimester: why cerclage therapy may not help

OBJECTIVE

The purpose of this study was to identify the risk factors that are associated with increased neonatal morbidity in patients who were treated for sonographic evidence of internal os dilation and distal cervical shortening during the second trimester.

STUDY DESIGN

From May 1998 to June 2000 patients between 16 and 24 weeks of gestation with the following sonographic criteria were randomly assigned to McDonald cerclage or no cerclage: internal os dilation and either membrane prolapse into the endocervical canal at least 25% of the total cervical length but not beyond the external os or a shortened distal cervix <2.5 cm. Before randomization, all patients were treated identically with an amniocentesis, multiple urogenital cultures, and therapy with indomethacin and clindamycin for 48 to 72 hours. Except for the cerclage, all patients were treated identically after randomization. Multiple variables of perinatal outcome were analyzed. A regression model with gestational age at delivery as the dependent variable was constructed and repeated with neonatal morbidity as the dependent variable. This model was applied to 3 populations: the cerclage group, the no cerclage group, and both groups combined.

RESULTS

Of the 135 patients, 20 patients declined randomization, and 2 patients were diagnosed with acute chorioamnionitis. Of the 113 patients remaining, 55 patients were randomly assigned to the cerclage group, and 58 patients were randomly assigned to the no cerclage group. There were 8 rescue cerclage procedures (4 in each group). Regression analysis showed that readmission for preterm labor, chorioamnionitis, and abruption were consistently associated with early gestational age at delivery and increased morbidity. Cerclage did not affect perinatal outcome.

CONCLUSION

The sonographic findings of second trimester internal os dilation, membrane prolapse, and distal cervical shortening likely represent a common pathway of several pathophysiologic processes. Use of cerclage does not alter any perinatal outcome variables. Increased neonatal morbidity in these patients appears to be associated with subclinical infection, preterm labor, and abruption.

Expression of functional luteinizing hormone (LH) receptor and its messenger ribonucleic acid in bovine endometrium: LH augmentation of cAMP and inositol phosphate in vitro and human chorionic gonadotropin (hCG) augmentation of peripheral prostaglandin in vivo

Bovine endometrium contains LH/hCG binding sites and LH increases endometrial production of prostaglandin H synthase-2 (PGHS-2) and prostaglandin synthesis. This study showed that uterine endometrium contained both LH receptor mRNA transcript and a 93-kDa immunoreactive protein that bound to anti-rat LH receptor antibody. LH receptor and its mRNA were expressed maximally in the endometrium of cows from the luteal phase compared to the follicular phase of the estrous cycle. Furthermore, there was a response shown when incubation of endometrial minces from both pre-estrus/estrus and luteal phase (but not post-ovulatory phase) with LH or oxytocin (20 ng/ml) that resulted in a significant (p<0.02) increase in cAMP and total inositol phosphates. When Day 15 cows were injected i.v. with 3000 units hCG, the increase in peripheral 13,14-dihydro-15-keto PGF(2alpha) was 2.5-fold higher than saline controls or oxytocin. We conclude that LH stimulates endometrial cAMP and total inositol phosphates which results in increased formation of uterine PGHS-2 similar to LH effect on ovarian PGHS-2. The increased 13,14-dihydro-15-keto PGF(2alpha) production induced in vivo by injections of hCG indicates that LH may have a reinforcing role in luteolysis.

Peptide mimics of SNARE transmembrane segments drive membrane fusion depending on their conformational plasticity

SNARE proteins are essential for different types of intracellular membrane fusion. Whereas interaction between their cytoplasmic domains is held responsible for establishing membrane proximity, the role of the transmembrane segments in the fusion process is currently not clear. Here, we used an in vitro approach based on lipid mixing and electron microscopy to examine a potential fusogenic activity of the transmembrane segments. We show that the presence of synthetic peptides representing the transmembrane segments of the presynaptic soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) synaptobrevin II (also referred to as VAMP II) or syntaxin 1A, but not of an unrelated control peptide, in liposomal membranes drives their fusion. Liposome aggregation by millimolar Ca(2+) concentrations strongly potentiated the effect of the peptides; this indicates that juxtaposition of the bilayers favours their fusion in the absence of the cytoplasmic SNARE domains. Peptide-driven fusion is reminiscent of natural membrane fusion, since it was suppressed by lysolipid and involved both bilayer leaflets. This suggests transient presence of a hemifusion intermediate followed by complete membrane merger. Structural studies of the peptides in lipid bilayers performed by Fourier transform infrared spectroscopy indicated mixtures of alpha-helical and beta-sheet conformations. In isotropic solution, circular dichroism spectroscopy showed the peptides to exist in a concentration-dependent equilibrium of alpha-helical and beta-sheet structures. Interestingly, the fusogenic activity decreased with increasing stability of the alpha-helical solution structure for a panel of variant peptides. Thus, structural plasticity of transmembrane segments may be important for SNARE protein function at a late step in membrane fusion.

Efficient biolistic transformation of maize (Zea mays L.) and wheat (Triticum aestivum L.) using the phosphomannose isomerase gene, pmi, as the selectable marker

A selectable marker system for plant transformation that does not require the use of antibiotics or herbicides was developed. The selectable marker consists of the manA gene from Escherichia coli under the control of a plant promoter that encodes for phosphomannose isomerase, pmi. Only transgenic plants were able to metabolize the selection agent, mannose, into a usable source of carbon, fructose. Transgenic plants were produced efficiently after delivery by Biolistics™ of the pmi gene into maize and wheat tissues, with mean transformation frequencies of 45% for maize and 20% for wheat. Adjustment of the sucrose and mannose levels in the selection medium essentially eliminated escapes. Transgenic events can be identified as early as 2 months for wheat and 4 months for maize. A simple test, a modified chlorophenol red assay, was used for early identification of transgenic events expressing the pmi gene. Transformation frequencies for both crops exceeded those obtained with the bar and pat genes with selection on either Basta^® or bialaphos.

Methodologic pitfalls in the determination of genetic anticipation: the case of Crohn disease

BACKGROUND

The term genetic anticipation is used when genetically transmitted disease manifests at increasingly younger ages with each succeeding generation: that is, if the offspring of patients develop the disease, they will tend to do so at an earlier age than their parents. In some monogenetic disorders, genetic anticipation has a biological basis in expanded genetic triplet repeats; however, some have claimed that it occurs in polygenic disorders, such as Crohn disease, in which its mechanism cannot be explained.

OBJECTIVE

To show how apparent changes in age at diagnosis of Crohn disease between generations, which could suggest genetic anticipation, can be an artifact of inadequate analysis based on age at diagnosis in cohorts that have not been followed for a sufficiently long time.

DESIGN

Comparison of ages at diagnosis of Crohn disease among different birth cohorts, before and after adjustment for observation time.

SETTING

Meyerhoff Center for Inflammatory Bowel Disease, Johns Hopkins Hospital, Baltimore, Maryland.

PATIENTS

928 consecutive outpatients with Crohn disease.

MEASUREMENTS

Trends in age at diagnosis of Crohn disease among birth cohorts were determined by calculating Pearson correlation coefficients and performing Kaplan-Meyer analysis before and after adjustment for observation time. Adjustment for observation time was performed by ensuring that the time during which all included patients were at risk for Crohn disease was equal and that all patients had developed disease by the end of the risk period.

RESULTS

Mean age at diagnosis decreased by approximately 5 years with each subsequent 10-year birth cohort on the basis of crude cross-sectional data that could suggest genetic anticipation between generations. However, after adjustment for observation time, the age at diagnosis decreased minimally, if at all, with each successive generation.

CONCLUSIONS

Apparent genetic anticipation can be explained by observational biases without invoking any additional genetic influences. Claims for genetic anticipation must be based on methods that properly account for the duration of observation in all persons being studied.

Can cardiac sonography and capnography be used independently and in combination to predict resuscitation outcomes?

OBJECTIVE

To measure the ability of cardiac sonography and capnography to predict survival of cardiac arrest patients in the emergency department (ED).

METHODS

Nonconsecutive cardiac arrest patients prospectively underwent either cardiac ultrasonography alone or in conjunction with capnography during cardiopulmonary resuscitation at two community hospital EDs with emergency medicine residency programs. Cardiac ultrasonography was carried out using the subxiphoid view during pauses for central pulse evaluation and end-tidal carbon dioxide (ETCO(2)) levels were monitored by a mainstream capnograph. A post-resuscitation data collection form was completed by each of the participating clinicians in order to assess their impressions of the facility of performance and benefit of cardiac sonography during nontraumatic cardiac resuscitation.

RESULTS

One hundred two patients were enrolled over a 12-month period. All patients underwent cardiac sonographic evaluation, ranging from one to five scans, during the cardiac resuscitation. Fifty-three patients also had capnography measurements recorded. The presence of sonographically identified cardiac activity at any point during the resuscitation was associated with survival to hospital admission, 11/41 or 27%, in contrast to those without cardiac activity, 2/61 or 3% (p < 0.001). Higher median ETCO(2) levels, 35 torr, were associated with improved chances of survival than the median ETCO(2) levels for nonsurvivors, 13.7 torr (p < 0.01). The multivariate logistic regression model, which evaluated the combination of cardiac ultrasonography and capnography, was able to correctly classify 92.4% of the subjects; however, of the two diagnostic tests, only capnography was a significant predictor of survival. The stepwise logistic regression model, summarized by the area under the receiver operator curve of 0.9, furthermore demonstrated that capnography is an outstanding predictor of survival.

CONCLUSIONS

Both the sonographic detection of cardiac activity and ETCO(2) levels higher than 16 torr were significantly associated with survival from ED resuscitation; however, logistic regression analysis demonstrated that prediction of survival using capnography was not enhanced by the addition of cardiac sonography.

Ovarian teratoma with a high level of differentiation

Dermoid cysts containing dental elements are reported in the literature. We report the first case of eight well-formed teeth in a mandible-like structure found in a teratoma.

Influence of myristoylation, phosphorylation, and deamidation on the structural behavior of the N-terminus of the catalytic subunit of cAMP-dependent protein kinase

A number of isoenzymes of the catalytic subunit of cAMP-dependent protein kinase arise through posttranslational modifications of the enzyme outside the catalytic domain; the biological significance of these is not yet fully clear. A clustering of sites for such modification exists at the N-terminus of the protein, where myristoylation (of Gly1), phosphorylation (at Ser10), and deamidation of Asn2 have been observed. As the first two are known to govern membrane binding and thus subcellular compartmentalization in some proteins, it was of interest to see whether the local structure of the N-terminus was being influenced by one or more of these modifications. A series of synthetic peptides mimicing the 16 N-terminal residues of the catalytic subunit Calpha was produced covering the full range of possible modifications, singly and in combination, and tested for possible effects on local structure by measuring the circular dichroism under varying polarity. It was found that myristoylation and phosphorylation modify the structure in this region in opposite ways and in a manner designed to amplify the action of a potential myristoyl/electrostatic switch. To what extent deamidation of Asn2 may oppose a potential membrane binding is unknown. Deamidation, however, had no effect on the structure of the peptide either alone or in combination with acylation and/or phosphorylation, suggesting that the change of the nuclear/cytoplasmic disribution in cells caused by deamidation [Pepperkok et al. (2000) J. Cell Biol. 148, 715-726] is due to a more complex signaling mechanism. The structural implications of the data are discussed.

Suicidal intent in patients with chronic pain

Suicidal ideation among individuals suffering from chronically painful conditions has not been widely studied, although rates of completed suicide are believed to be elevated in this population relative to the general population. The psychiatric literature on suicide documents the importance of controlling for the severity of depression when studying factors associated with suicidal ideation, attempts, or completion. The present study examined the relationships between suicidal ideation and the experience of pain, pain-related disability, and pain coping efforts among a sample of individuals experiencing chronically painful conditions. Of 200 patients evaluated on an inpatient rehabilitation unit in a psychiatric service, 13 individuals (6.5%) reported suicidal intent on a commonly used self-report measure of symptoms of depression, the Beck Depression Inventory. This group was compared to a matched (age, sex, pain duration) group of similarly depressed individuals (N=13) and a matched group of non-depressed individuals (N=13) on measures of pain, disability, pain beliefs, and pain coping strategies. A history of a suicide attempt was associated with suicidal intent. Family history of substance abuse was significantly more prevalent among the depressed groups, regardless of suicidal thinking. The depressed/suicidal group and depressed/non-suicidal groups reported higher levels of pain, higher levels of pain-related disability, lower use of active coping, and higher use of passive coping compared to the non-depressed group. The depressed groups did not differ from one another on any of the measures of pain experience. Depression, not suicidal status, consistently predicted level of functioning. The prevalence of suicidal intent was comparable to rates observed in other studies and relatively low. When individuals with chronic pain report suicidal intent, it is imperative that measures preventing self-harm be implemented immediately and the patient's depression be treated aggressively.

Characterization of peptide substrates and viral enzyme that affect the cleavage site specificity of the human spumaretrovirus proteinase

Oligopeptides that correspond to proteolytic cleavage site junctions of the native Gag and Pol proteins are specifically cleaved by retroviral aspartate proteases (PRs). The role of the flap subdomain of the PR of the human spumaretrovirus (HSRV) and of substrate peptides in cleavage site specificity was analyzed by site-directed mutagenesis. Native and mutant peptides were subjected to proteolysis by the authentic and mutated recombinant viral enzyme. The results reveal that Glu residue 54 of the HSRV PR is an essential specificity determinant for proteolytic processing of the structural proteins. Peptides that represent in vivo cleavage sites were susceptible to proteolysis by the recombinant HSRV PR, but one peptide located at the junction between the PR and reverse transcriptase domains was completely resistant to cleavage. Thus the data indicate that a proteolytic cleavage between these domains does not occur in vivo. Naturally occurring and mutant forms of the cleavage-resistant peptide were therefore analyzed by circular dichroism to determine if differences existed in the secondary structures of the peptides that did or did not serve as substrates. The data show that differences in the secondary structure of the native and mutant peptides analyzed does not seem to play a crucial role for cleavage site specificity in HSRV PR. Instead highly conserved hydrophobic residues at distinct positions of the HSRV cleavage site junctions contribute to the specificity observed as reported for HIV-1 PR.

Hsp70-RAP46 interaction in downregulation of DNA binding by glucocorticoid receptor

Receptor-associating protein 46 (RAP46) is a cochaperone that regulates the transactivation function of several steroid receptors. It is transported into the nucleus by a liganded glucocorticoid receptor where it downregulates DNA binding and transactivation by this receptor. The N- and C-termini of RAP46 are both implicated in its negative regulatory function. In metabolic labelling experiments, we have shown that the N-terminus of RAP46 is modified by phosphorylation, but this does not contribute to the downregulation of glucocorticoid receptor activity. However, deletion of a sequence that binds 70 kDa heat shock protein (Hsp70) and the constitutive isoform of Hsp70 (Hsc70) at the C-terminus of RAP46 abrogated its negative regulatory action. Surface plasmon resonance studies showed that RAP46 binds the glucocorticoid receptor only when it has interacted with Hsp70/Hsc70, and confocal immunofluorescence analyses revealed a nuclear transport of Hsp70/Hsc70 by the liganded receptor. Together these findings demonstrate an important contribution of Hsp70/Hsc70 in the binding of RAP46 to the glucocorticoid receptor and suggest a role for this molecular chaperone in the RAP46-mediated downregulation of glucocorticoid receptor activity.