Patient and family perceptions of a discharge bedside board

Objective

To explore patient and family perspectives of a discharge bedside board for supporting engagement in patient care and discharge planning to inform tool revision.

Methods

This qualitative descriptive study included 45 semi-structured interviews with a purposeful sample of English-speaking patients (n = 44; mean age 58.5 years) and their family members (n = 5) across seven adult inpatient units at a tertiary acute care hospital in mid-western Canada. Thematic (interviews), content (board, organization procedure document), and framework-guided integrated (all data) analyses were performed.

Results

Four themes were generated from interview data: understanding the board, included essential information to guide care, balancing information on the board, and maintaining a sense of connection. Despite application inconsistencies, documented standard procedures aligned with recommended board (re)orientation, timely patient-friendly content, attention to privacy, and patient-provider engagement strategies.

Conclusion

Findings indicate the tool supported consultation and some involvement level engagement in patient care and discharge. Board information was usually valued, however, perceived procedural gaps in tool education, privacy, and the quality of tool-related communication offer opportunities to strengthen patients' and families' tool experience.

Innovation

Novel application of a continuum engagement framework in the exploration of multiple data sources generated significant insights to guide tool revision.

Burden of Allergic Disease in Racial and Ethnic Structurally Oppressed Communities Within Canada and the United States: A Scoping Review

BACKGROUND

The social determinants of health have been extensively studied as potential mediating variables in the development and/or progression of many chronic illnesses, including allergic diseases, and may contribute to social inequities as barriers in accessing health care.

OBJECTIVE

We aimed to perform a scoping literature review to describe the burden of disease and access to health care for treatment of allergic disease within literature specific to structurally oppressed racial and ethnic populations.

METHODS

We performed a scoping review, guided by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines for Scoping Reviews, of 3 scientific databases and 5 relevant gray literature sites. Search strategy including keywords describing race and ethnicity were selected based on the acceptable nomenclature in Canada and the United States. We imposed no restrictions on date or country of publication, study design, or age of participants.

RESULTS

Our literature search yielded 1,198 potentially relevant articles following deduplication. After title and abstract, and subsequently full-text screening, a total of 12 (1.08% of all articles) were included. These 12 included studies pointed toward a higher burden of allergic and atopic disease, including increased presentations to emergency departments, hospitalizations, mortality, younger age of diagnosis, and/or greater severity of disease, among Black or African American individuals, than the general population. Allergies beyond the top 9 food allergens, eosinophilic esophagitis, and asthma appeared to be more prevalent and more severe in this population than in the general population. There appears to be an increased burden of allergic and atopic disease among the Indigenous Peoples of Canada, whereas this was not noted for Latinx or Hispanic populations, in part due to a paucity of studies involving these populations. Owing to a lack of published literature, no conclusions could be drawn regarding allergy and atopy in Native American populations.

CONCLUSIONS

Structurally oppressed racial and ethnic communities may face an increased burden of allergic and atopic disease-but that this may be magnified by issues regarding oppression, access, and social environment that warrant further investigation.

Food Allergy, Eating Disorders and Body Image

Background/Introduction:

Food allergy (FA) management involves avoiding allergenic foods to prevent an adverse reaction. Affected individuals spend substantial amounts of time thinking about food and the impact it has on their bodies. As such, we posit sustained awareness of food choices may contribute to distorted body image and disordered eating. We performed a narrative review to glean insight into associations between FA, body image and eating disorders.

Methods:

A literature search of Scopus, PsycINFO, PubMed and Google Scholar was conducted connecting terms for “food allergy” with terms for “body image” and “eating disorders”. Title and abstract screening were independently performed by two reviewers, with relevant abstracts carried forward to full text screening.

Results:

159 articles were eligible for full text screening and a total of 12 publications were ultimately included in this narrative review, and 1 article from the grey literature. Adolescents and adults both reported feeling as though their bodies were “defective” and were found to have integrated their FA as a stable facet of their identities. In addition, FA was overwhelmingly associated with prevalence of eating disorders and eating disorder-like symptoms. Disturbed body image was found to be a mediating variable for the development of disordered patterns of eating in food allergic individuals.

Limitations:

Few studies appeared to consider comorbidities as confounders. Also, many studies employed convenience sampling, which does limit generalizability of conclusions.

Discussion/Conclusion:

Based on a small body of literature, there appears to be a potential association between FA and distorted body image and disordered eating.

Prometastatic CXCR4 and Histone Methyltransferase EZH2 are Upregulated in SMARCB1/INI1-deficient and TP53-mutated Metastatic Poorly Differentiated Chordoma to the Liver

Introduction/Objective

Chordoma is a rare tumor most commonly arising in the sacrococcygeal region from notochord remnants. Usually, these tumors are locally invasive and recurrent, but do not have the capability to metastasize. A newly described aggressive variant called poorly differentiated chordoma is different than conventional chordoma in that it does not have the well-differentiated histologic appearance of conventional chordoma and also exhibits loss of SMARCB1/INI1.

Methods

Herein, we describe a case of poorly differentiated chordoma with SMARCB1/INI1 loss, concurrent TP53 mutation and Rb1 loss.

Results

The patient is a 55-year-old man with a history of a previously resected sacrococcygeal chordoma, who was found to have new hepatic, lung, and adrenal lesions. Biopsy of the liver showed sheets of malignant epithelioid cells with vacuolated cytoplasm, areas of necrosis, and up to 5 mitoses in one high power field. No physaliferous features or matrix material were seen. After an extensive panel of immunohistochemical markers, the origin of the metastatic tumor could not be determined and the tumor was only positive for Cam5.2, EMA, and CD56. Brachyury was performed due to the patient’s previous history and was positive. Genomic testing showed a SMARCB1 mutation, a TP53 mutation, and RB1 loss. Additional markers were performed and the tumor showed a Ki-67 proliferation index of approximately 80%, mutant p53 protein, loss of INI1, and strong expression of prometastatic CXCR4 and the histone methyltransferase EZH2. The most recent follow-up of the patient showed that the patient was receiving palliative care.

Conclusion

Poorly differentiated chordoma is a highly aggressive variant of chordoma with few cases reported. This case of SMARCB1/INI-deficient, poorly differentiated chordoma also showed concurrent TP53 mutation and loss of RB1, which resulted in malignant transformation with loss of differentiation, cell cycle progression, up-regulation of prometastatic CXCR4 and the histone methyltransferase EZH2 causing aggressive behavior and metastasis.

Intestine Transplantation Across a Positive Crossmatch With Preformed Donor-Specific Antibodies

BACKGROUND

We describe our experience using a modified protocol for immunosuppression for intestine transplantation across a positive crossmatch. Patients who underwent transplantation in 2013 were evaluated over a 12-month period for rejection and infectious events with comparison to procedure-matched controls on our standard protocol of immunosuppression.

PATIENTS AND METHODS

We used a modified protocol for intestine and multivisceral transplantation for patients with a positive flow crossmatch. In addition to our standard protocol, patients with positive crossmatch were given rituximab and intravenous immunoglobulin (IVIg) preoperatively. DSA was sent for clinical evaluation at monthly intervals. Patients were screened for rejection by endoscopic evaluation.

RESULTS

Four patients underwent transplantation within a single year across a positive crossmatch. Two received isolated intestine transplants and 2 had multivisceral transplantation (MVT). During the 12-month follow-up, 1 patients had an episode of severe acute cellular rejection, which was managed with increased immunosuppression. None of the patients had episodes of cytomegalovirus infection. One patient developed major infection and 3 patients developed minor bacterial infections. Among procedure-matched controls with negative final crossmatch on standard management (no preoperative rituximab or IVIg), 2 developed mild acute cellular rejection and 2 developed minor infections. One developed cytomegalovirus viremia with invasion to the colonic mucosa.

CONCLUSIONS

We report our protocol for immunosuppression for IT and MVT across a positive crossmatch. This allowed transplantation despite the presence of a positive crossmatch, with low rejection rates but potentially increased risk for major infections compared to the negative crossmatch controls on our standard protocol.

Clinical demonstration of efficiency and reversibility of hypoxic pulmonary vasoconstriction in a patient presenting with unilateral incomplete bronchial occlusion

Although hypoxic pulmonary vasoconstriction is a well-recognized physiological phenomenon it is unusual to observe and assess its efficiency in clinical practice. Here, we report the case of a 50-year-old female who presented with unilateral incomplete bronchial occlusion due to a carcinoid tumor involving the left main bronchus in the absence of atelectasis. Ventilation-perfusion imaging revealed absent ventilation and perfusion to the left lung. She underwent bronchotomy and removal of the tumor. One month after the operation a further ventilation-perfusion lung scan revealed complete restoration of ventilation to the left lung and almost complete recovery of the perfusion. This unusual case demonstrates the marked efficiency of hypoxic pulmonary vasoconstriction at the level of a single lung and its reversible nature following relief of regional hypoxia.

The Warfarin/Aspirin Study in Heart failure (WASH): a randomized trial comparing antithrombotic strategies for patients with heart failure

BACKGROUND

Heart failure is commonly associated with vascular disease and a high rate of athero-thrombotic events, but the risks and benefits of antithrombotic therapy are unknown.

METHODS

The current study was an open-label, randomized, controlled trial comparing no antithrombotic therapy, aspirin (300 mg/day), and warfarin (target international normalized ratio 2.5) in patients with heart failure and left ventricular systolic dysfunction requiring diuretic therapy. The primary objective was to demonstrate the feasibility and inform the design of a larger outcome study. The primary clinical outcome was death, nonfatal myocardial infarction, or nonfatal stroke.

RESULTS

Two hundred seventy-nine patients were randomized and 627 patient-years exposure were accumulated over a mean follow-up time of 27 +/- 1 months. Twenty-six (26%), 29 (32%), and 23 (26%) patients randomized to no antithrombotic treatment, aspirin, and warfarin, respectively, reached the primary outcome (ns). There were trends to a worse outcome among those randomized to aspirin for a number of secondary outcomes. Significantly (P =.044) more patients randomized to aspirin were hospitalized for cardiovascular reasons, especially worsening heart failure.

CONCLUSIONS

The Warfarin/Aspirin Study in Heart failure (WASH) provides no evidence that aspirin is effective or safe in patients with heart failure. The benefits of warfarin for patients with heart failure in sinus rhythm have not been established. Antithrombotic therapy in patients with heart failure is not evidence based but commonly contributes to polypharmacy.

An Lrp-type transcriptional regulator from Agrobacterium tumefaciens condenses more than 100 nucleotides of DNA into globular nucleoprotein complexes

The PutR protein of Agrobacterium tumefaciens positively regulates expression of the putA gene in response to exogenous proline, resulting in the utilization of proline as a source of carbon and nitrogen. PutR activity required a region of DNA extending more than 106 nt upstream of the putA transcription start site. Purified PutR bound to this region with high degree of affinity and repressed expression of the putR promoter in vitro. PutR also activated the putA promoter in vitro in the presence of proline, though less strongly than in whole cells. PutR protected a DNA interval extending from nucleotides -30 to -140, but protected only one helical face over most of this interval, suggesting that it may bind only to this face of the DNA. The addition of proline caused a slight decrease in binding affinity and altered DNase I protection patterns along the entire length of the binding site. PutR-DNA complexes were found by atomic force microscopy to be globular rather than elongated. Although the DNA fragment in these complexes was 190 nm in length, the length of the visible DNA was only 150 nm, indicating that 40 nm of DNA (115 nt) must be condensed with protein. PutR caused a net bend of this binding site, and under some conditions, proline shifted the center of this bend by one helical turn.

Mechanisms of altered excitation-contraction coupling in canine tachycardia-induced heart failure, II: model studies

Ca2+ transients measured in failing human ventricular myocytes exhibit reduced amplitude, slowed relaxation, and blunted frequency dependence. In the companion article (O'Rourke B, Kass DA, Tomaselli GF, Kääb S, Tunin R, Marbán E. Mechanisms of altered excitation-contraction coupling in canine tachycardia-induced heart, I: experimental studies. Circ Res. 1999;84:562-570), O'Rourke et al show that Ca2+ transients recorded in myocytes isolated from canine hearts subjected to the tachycardia pacing protocol exhibit similar responses. Analyses of protein levels in these failing hearts reveal that both SR Ca2+ ATPase and phospholamban are decreased on average by 28% and that Na+/Ca2+ exchanger (NCX) protein is increased on average by 104%. In this article, we present a model of the canine midmyocardial ventricular action potential and Ca2+ transient. The model is used to estimate the degree of functional upregulation and downregulation of NCX and SR Ca2+ ATPase in heart failure using data obtained from 2 different experimental protocols. Model estimates of average SR Ca2+ ATPase functional downregulation obtained using these experimental protocols are 49% and 62%. Model estimates of average NCX functional upregulation range are 38% and 75%. Simulation of voltage-clamp Ca2+ transients indicates that such changes are sufficient to account for the reduced amplitude, altered shape, and slowed relaxation of Ca2+ transients in the failing canine heart. Model analyses also suggest that altered expression of Ca2+ handling proteins plays a significant role in prolongation of action potential duration in failing canine myocytes.

Mannopinic acid and agropinic acid catabolism region of the octopine-type Ti plasmid pTi15955

Octopine-type Ti plasmids such as pTi15955, pTiA6 and pTiR10 direct the catabolism of at least eight compounds called opines that are released from crown gall tumours. Four of these compounds are denoted mannityl opines, each of which possesses a D-mannityl substituent on the nitrogen atom of either glutamate or glutamine. We have analysed a 20 kb region of the Ti plasmid pTi15955 that is required for the catabolism of two such opines, mannopinic acid and agropinic acid. A total of 12 genes in four operons were identified by DNA sequence analysis. Transposons Tn5lacZ and MudK were used to mutagenize these genes and to create aga-lacZ and moa-lacZ translational fusions. The expression of all fusions was induced by agropinic acid and by mannopinic acid. One of these four operons encodes an agropinic acid permease, whereas a second one encodes a mannopinic acid permease. A third operon contains three genes encoding probable catabolic enzymes, two of which (AgaF and AgaG) are thought to convert agropinic acid to mannopinic acid, while the third (AgaE) probably converts mannopinic acid to mannose and glutamate. AgaE resembles a bacterial amino acid deaminase, whereas AgaF and AgaG resemble two bacterial proteins that together catabolize substituted hydantoins, whose chemical structure resembles that of agropinic acid. The remaining operon encoded the MoaR protein, a negative regulator of itself and of the other three operons.

Modeling the cellular basis of altered excitation-contraction coupling in heart failure

Ca transients measured in failing human ventricular myocytes exhibit reduced amplitude and slowed relaxation [Beuckelmann, D.J., Nabauer, M., Erdmann, E., 1992. Intracellular calcium handling in isolated ventricular myocytes from patients with terminal heart failure. Circulation 85, 1046-1055; Gwathmey, J.K., Copelas, L., MacKinnon, R., Schoen, F.J., Feldman, M.D., Grossman, W., Morgan, J.P., 1987. Abnormal intracellular calcium handling in myocardium from patients with end-stage heart failure. Circ. Res. 61, 70-76; Kaab, S., Nuss, H. B., Chiamvimonvat, N., O'Rourke, B., Pak, P.H., Kass, D.A., Marban, E., Tomaselli, G.F., 1996. Ionic mechanism of action potential prolongation in ventricular myocytes from dogs with pacing-induced heart failure. Circ. Res. 78(2); Li, H.G., Jones, D.L., Yee, R., Klein, G.J., 1992. Electrophysiologic substrate associated with pacing-induced hert failure in dogs: potential value of programmed stimulation in predicting sudden death. J. Am. Coll. Cardiol. 19(2), 444-449; Vermeulen, J.T., McGuire, M.A., Opthof, T., Colonel, R., Bakker, J.M.T.d., Klopping, C., Janse, M.J., 1994. Triggered activity and automaticity in ventricular trabeculae of failing human and rabbit hearts. Cardiovasc. Res. 28, 1547-1554.] and blunted frequency dependence [Davies, C.H., Davia, K., Bennett, J.G., Pepper, J.R., Poole-Wilson, P.A., Harding, S.E., 1995. Reduced contraction and altered frequency response of isolated ventricular myocytes from patients with heart failure. Circulation, 92, 2540-2549; Hasenfuss, G., Reinecke, H., Studer, R., Meyer, M., Pieske, B., Holtz, J., Holubarsch, C., Posival, H., Just, H., Drexler, H., 1994. Relation between myocardial function and expression of sarcoplasmic reticulum Ca-ATPase in failing and nonfailing human myocardium. Circ. Res. 75, 434-442; Hasenfuss, G., Reinecke, H., Studer, R., Pieske, B., Meyer, M., Drexler, H., Just, H., 1996. Calcium cycling proteins and force-frequency relationships in heart failure. Basic Res. Cardiol. 91, 17-22; Monte, F.D., O'Gara, P., Poole-Wilson, P.A., Yacoub, M., Harding, S.E., 1995. Cell geometry and contractile abnormalities of myocytes from failing human left ventricle.

Left atrial myxoma presenting with embolism to the aorta

We present a patient with left atrial myxoma embolizing to the ascending aorta. The features have not been reported previously and were diagnosed with transesophageal echocardiography.

The glutamic acid residue at amino acid 261 of the alpha subunit is a determinant of the intrinsic efficiency of RNA polymerase at the metE core promoter in Escherichia coli

A mutation in the rpoA gene (which encodes the alpha subunit of RNA polymerase) that changed the glutamic acid codon at position 261 to a lysine codon decreased the level of expression of a metE-lacZ fusion 10-fold; this decrease was independent of the MetR-mediated activation of metE-lacZ. Glutamine and alanine substitutions at this position are also metE-lacZ down mutations, suggesting that the glutamic acid residue at position 261 is essential for metE expression. In vitro transcription assays with RNA polymerase carrying the lysine residue at codon 261 indicated that the decreased level of metE-lacZ expression was not due to a failure of the mutant polymerase to respond to any other trans-acting factors, and a deletion analysis using a lambda metE-lacZ gene fusion suggested that there is no specific cis-acting sequence upstream of the -35 region of the metE promoter that interacts with the alpha subunit. Our data indicate that the glutamic acid at position 261 in the alpha subunit of RNA polymerase influences the intrinsic ability of the enzyme to transcribe the metE core promoter.

A mutation in the rpoA gene encoding the alpha subunit of RNA polymerase that affects metE-metR transcription in Escherichia coli

The DNA-binding protein MetR belongs to the LysR family of transcriptional activators and is required for expression of the metE and metH promoters in Escherichia coli. However, it is not known if this activation is mediated by a direct interaction of MetR with RNA polymerase. In a search for RNA polymerase mutants defective in MetR-mediated activation of the metE gene, we isolated a mutation in the alpha subunit of RNA polymerase that decreases metE expression independently of the MetR protein. The mutation does not affect expression from the metH promoter, suggesting that the alpha subunit of RNA polymerase interacts differently at these two promoters. The mutation was mapped to codon 261 of the rpoA gene, resulting in a change from a glutamic acid residue to a lysine residue. Growth of the mutant is severely impaired in minimal medium even when supplemented with methionine and related amino acids, indicating a pleiotropic effect on gene expression. This rpoA mutation may identify either a site of contact with an as yet unidentified activator protein for metE expression or a site of involvement by the alpha subunit in sequence-specific recognition of the metE promoter.

Partial cDNA cloning and NGF regulation of a rat 5-HT3 receptor subunit

Nerve growth factor (NGF) stimulates 5-HT3 receptor expression although the mechanism(s) responsible for this effect are unknown. We report the nucleotide and deduced amino acid sequences of a nearly complete rat 5-HT3 receptor subunit and use the sequence to develop a reverse transcription-polymerase chain reaction (RT-PCR) assay that measures 5-HT3 mRNA. Exposure of PC12 cells to NGF results in increasing steady-state levels of 5-HT3 mRNA. The four-fold increase in mRNA correlates with and is sufficient to account for increases in receptor measured by agonist induction of whole cell currents.

Plasmid addiction genes of bacteriophage P1: doc, which causes cell death on curing of prophage, and phd, which prevents host death when prophage is retained

P1 lysogens of Escherichia coli carry the prophage as a stable low copy number plasmid. The frequency with which viable cells cured of prophage are produced is about 10(-5) per cell per generation. Here we show that a significant part of this remarkable stability can be attributed to a plasmid-encoded mechanism that causes death of cells that have lost P1. In other words, the lysogenic cells appear to be addicted to the presence of the prophage. The plasmid withdrawal response depends on a gene named doc (death on curing), encoding a 126 amino acid protein. Expression of doc is not SOS-inducing and killing by Doc is recA-independent. In cells that retain P1 the killing is prevented by the product of a gene named phd (prevent host death), encoding a 73 amino acid protein. The genes phd and doc have been cloned and expressed from a 0.7 kb segment of P1 DNA. The two genes constitute an operon and the synthesis of Doc appears to be translationally coupled to that of Phd. Homologs of the P1 addiction genes are found elsewhere, but phd and doc are unrelated to previously described genes of other plasmids that also cause an apparent increase in plasmid stability by post-segregational killing.

Prognostic significance of electrocardiographic persistent ST depression in patients with their first myocardial infarction in the placebo arm of the Beta-Blocker Heart Attack Trial

The prognostic significance of ST segment depression in patients with their first acute myocardial infarction was investigated in 1444 patients with an acute myocardial infarction, who were randomly assigned to the placebo arm of the Beta-Blocker Heart Attack Trial (BHAT). Patients were divided retrospectively into three groups based on the presence or absence of > or = 1 mm ST segment depression in two contiguous leads of a 12-lead electrocardiogram obtained during the first few days after admission and at the time of randomization, which occurred at 9.7 +/- 3.3 days after the index myocardial infarction. Group 1 included 392 patients with no ST segment depression, group 2 comprised 713 patients with transient ST segment depression in the first few days after admission or at the time of randomization, and group 3 included 339 patients with persistent ST segment depression in the first few days after admission and at the time of randomization. At a median follow-up of 26 months, the mortality rate was 4.9% in group 1, 7.6% in group 2, and 13.6% in group 3. When Cox regression was used to adjust for baseline differences in other variables, the differences between the three groups continued to be highly significant (p = 0.005; 95% confidence intervals [0.6 and 1.4]). We conclude that persistent and transient ST segment depression in patients with their first myocardial infarction are strong predictors of increased long-term mortality when compared to patients without ST segment depression. These findings should be taken into consideration when stratifying patients at risk in the post-myocardial infarction period.

Left ventricular shape is the primary determinant of functional mitral regurgitation in heart failure

OBJECTIVES

The aim of this study was to examine the temporal association between the onset of functional mitral regurgitation and the development of changes in left ventricular shape, chamber enlargement, mitral anulus dilation and regional wall motion abnormalities during the course of evolving heart failure.

BACKGROUND

Despite extensive characterization, the exact etiology of functional mitral regurgitation in patients with chronic heart failure remains unknown.

METHODS

Heart failure was produced in seven dogs by multiple sequential intracoronary microembolizations. Serial changes in left ventricular chamber volume and shape were evaluated from ventriculograms. Changes in mitral anulus diameter and ventricular regional wall motion abnormalities were evaluated echocardiographically. The presence and severity of mitral regurgitation were determined with Doppler color flow mapping. Measurements were obtained at baseline and then biweekly until mitral regurgitation was first observed.

RESULTS

No dog had mitral regurgitation at baseline but all developed mild to moderate regurgitation 12 +/- 1 weeks after the first embolization. The onset of mitral regurgitation was not associated with an increase in left ventricular end-diastolic volume relative to baseline (58 +/- 3 vs. 62 +/- 3 ml), mitral anulus diameter (2.4 +/- 0.1 vs. 2.4 +/- 0.1 cm) or wall motion abnormalities of left ventricular wall segments overlying the papillary muscles. In contrast, the onset of mitral regurgitation was accompanied by significant changes in global left ventricular shape evidenced by increased end-systolic chamber sphericity index (0.22 +/- 0.02 vs. 0.30 +/- 0.01) (p < 0.01) and decreased end-systolic major axis/minor axis ratio (1.71 +/- 0.05 vs. 1.43 +/- 0.04) (p < 0.001).

CONCLUSIONS

These data indicate that transformation of left ventricular shape (increased chamber sphericity) is the most likely substrate for the development of functional mitral regurgitation.

Left ventricular shape: a factor in the etiology of functional mitral regurgitation in heart failure

The relationship between left ventricular (LV) shape and functional mitral regurgitation (MR) was examined in 18 dogs with long-standing heart failure produced by multiple sequential intracoronary microembolizations. Global LV shape changes were evaluated from angiographic silhouettes obtained at baseline (before embolization) and during heart failure. LV shape changes at end systole and end diastole were quantitated based upon the ratio of the major-to-minor axis and the sphericity index. Among the 18 dogs studied, 11 developed 1+ to 3+ MR during heart failure and seven did not. There was no difference among the two groups with respect to hemodynamics, LV ejection fraction, chamber volume, and regional wall motion. A significant difference, however, was observed between the two groups with respect to the global indexes of LV shape. In dogs with MR, the end-systolic major-to-minor axis ratio decreased 29 +/- 3% between baseline and heart failure compared with only a 16 +/- 3% decrease in dogs without MR (p less than 0.01). In dogs with MR, the end-systolic sphericity index increased 72 +/- 11% between baseline and heart failure compared with an increase of only 30 +/- 5% in dogs without MR (p less than 0.02). Significant and directionally similar differences were observed during end diastole. These data indicate that in heart failure functional MR is associated with a more spherical LV and is not the result of simple LV chamber enlargement. Shape changes of the LV that occur in heart failure may be an important determinant of functional MR.

Mechanism of functional mitral regurgitation during acute myocardial ischemia

The mechanism and temporal manifestation of functional mitral regurgitation after acute myocardial ischemia were examined in eight dogs. Regional ischemia was produced by selective microembolization of the left circumflex coronary artery. Mitral regurgitation and regional left ventricular wall motion abnormalities were evaluated with use of Doppler color flow mapping and two-dimensional echocardiography, respectively. Measurements were made at baseline (before embolization) and were repeated at 30 min and 3 weeks after embolization. Mitral regurgitation developed in all dogs 30 min after embolization and completely subsided 3 weeks later. There was no evidence of mitral valve prolapse, mitral anulus dilation or left ventricular segmental dyskinesia at any time during the study. Regional wall motion analysis showed only hypokinesia of the left ventricular segment overlying the papillary muscle at 30 min with subsequent normalization of the segment at 3 weeks. Mitral regurgitation was accompanied by an increase of the end-systolic distance between the mitral anulus plane and the point of coaptation of the mitral leaflets. This distance was 0.5 +/- 0.1 cm at baseline, increased to 0.9 +/- 0.1 cm 30 min after the embolization (p less than 0.001) and returned to near baseline (0.6 +/- 0.1 cm) 3 weeks after the embolization. These data indicate that mitral valve prolapse, mitral anulus dilation and regional left ventricular dyskinesia are not necessary conditions for the development of functional mitral regurgitation after acute myocardial ischemia. Instead, hypokinesia of the ventricular segment overlying the papillary muscle and leading to retraction of the mitral leaflets toward the apex appears to be a sufficient condition for incomplete leaflet coaptation.

A canine model of chronic heart failure produced by multiple sequential coronary microembolizations

A canine model of chronic heart failure was produced by multiple sequential intracoronary embolizations with microspheres. Twenty closed-chest dogs underwent three to nine intracoronary embolizations performed 1-3 wk apart. Embolizations were discontinued when left ventricular (LV) ejection fraction was less than 35%. LV ejection fraction was 64 +/- 2% at baseline and decreased to 21 +/- 1% at 3 mo after the last embolization (P less than 0.001). During the same period, LV end-diastolic pressure increased from 6 +/- 1 to 22 +/- 3 mmHg (P less than 0.001); LV end-diastolic volume increased from 64 +/- 3 to 101 +/- 6 6 ml (P less than 0.001), and cardiac output decreased from 2.9 +/- 0.2 to 2.3 +/- 0.1 l/min (P less than 0.01). These changes were accompanied by significant increases of pulmonary artery wedge pressure and systemic vascular resistance. Plasma norepinephrine increased from 332 +/- 17 pg/ml at baseline to 791 +/- 131 pg/ml at 3 mo after the last embolization (P less than 0.01); plasma levels of atrial natriuretic factor increased from 12.7 +/- 10.0 to 28.8 +/- 8.6 pmol/l (P less than 0.01), whereas plasma renin activity remained unchanged. Gross and microscopic postmortem examination showed patchy myocardial fibrosis and LV hypertrophy. We conclude that multiple intracoronary embolizations with microspheres, separated in time, can lead to chronic heart failure in dogs. The preparation is stable and reproducible and manifests many of the sequelae of heart failure that result from loss of contractile myocardium.

Nutritive value of human milk and nutritional status of wives of army personnel of low income from Rawalpindi

The nutritional status and proximate composition, fatty acid profile and mineral composition of milk from 26 wives of army personnel of low income group from Rawalpindi was investigated. The body mass index ranged from 13.5 to 23.7, hemoglobin from 8.6 to 14.8 G/dl, serum protein from 4.8 to 7.5 G and serum albumin from 3.3 to 4.8 G%. Milk protein content varied from 0.6 to 2.4%, fat from 1.0 to 3.7% [corrected]. Palmitic acid was the major fatty acid in milk whose concentration ranged from 34.4 to 47.1% [corrected] and the linoleic acid from 6.9-15.4% [corrected]. The calcium content of milk varied from 7.9-87.1 mg%, iron from traces to 0.44 mg% and zinc from 0.02-1.28 mg%.

Participation of the lytic replicon in bacteriophage P1 plasmid maintenance

P1 bacteriophage carries at least two replicons: a plasmid replicon and a viral lytic replicon. Since the isolated plasmid replicon can maintain itself stably at the low copy number characteristic of intact P1 prophage, it has been assumed that this replicon is responsible for driving prophage replication. We provide evidence that when replication from the plasmid replicon is prevented, prophage replication continues, albeit at a reduced rate. The residual plasmid replication is due to incomplete repression of the lytic replicon by the c1 immunity repressor. Incomplete repression was particularly evident in lysogens of the thermoinducible P1 c1.100 prophage, whose replication at 32 degrees C remained almost unaffected when use of the plasmid replicon was prevented. Moreover, the average plasmid copy number of P1 in a P1 c1.100 lysogen was elevated with respect to the copy number of P1 c1+. The capacity of the lytic replicon to act as an auxiliary in plasmid maintenance may contribute to the extraordinary stability of P1 plasmid prophage.

Multiple chromosomes of Azotobacter vinelandii

The number of copies of the genes leuB, nifH, nifD, and nifK per cell of Azotobacter vinelandii has been determined to be about 80. A beta-lactamase gene was integrated into the A. vinelandii chromosome by single-point crossover. Subsequently, we have been able to detect nearly 80 copies of this beta-lactamase gene per cell of A. vinelandii when cultured for a large number of generations in the presence of ampicillin. The multiple copies of the beta-lactamase gene do not seem to be present on a single chromosome, as evident from the fragment obtained by digestion of cellular DNA with the appropriate restriction endonuclease. The kinetics of renaturation of DNA of A. vinelandii is suggestive of complexity similar to that of Escherichia coli. The DNA content of A. vinelandii, however, is 40 times that of E. coli. All these indicate the presence of multiple chromosomes, possibly as many as 80, in A. vinelandii.

Hypolipidemic activity of trimethylamine-carbomethoxyborane and related derivatives in rodents

A number of substituted amine-carboxyborane esters were examined for their hypolipidemic activity in rodents. Trimethylamine-carbomethoxyborane, Me3NBH2C(O)OMe, was observed to be the most effective hypolipidemic agent in the rodent at the low dose of 8 mg/kg/d. This agent effectively increased the high density lipoprotein (HDL) cholesterol content and lowered the low density lipoprotein (LDL) cholesterol and triglyceride contents of rat lipoproteins. Furthermore, the agent accelerated cholesterol excretion from the body of the rat and reduced the activity of the rate-limiting enzyme involved in the de novo synthesis of lipids in the liver. The agent has a safe therapeutic index, and appeared to have more promise as a therapeutic agent than other borane esters.