Usefulness of nuclear magnetic resonance imaging for evaluation of pericardial effusions, and comparison with two-dimensional echocardiography

Nuclear magnetic resonance (NMR) imaging clearly delineates cardiovascular structures without interference from overlying bone and lung tissue. The techniques of NMR imaging and echocardiography were compared in 26 patients with pericardial effusions, 10 of whom had associated pleural effusions. In those patients with fluid detected by both techniques, estimated size of the effusion tended to be somewhat larger by NMR. NMR imaging detected several small pericardial effusions that were not visualized by echocardiography. Both techniques demonstrated loculation well, although NMR imaging was better for detecting fluid located superiorly at the aortic pericardial reflection site, medially at the border of the right atrium and posteriorly at the left ventricular apex. In the 14 patients with documented exudative effusions (10 pericardial, 4 pleural) NMR signals of varying intensity were present in the effusion. One patient had a documented transudative effusion and no NMR signal was observed in the fluid. NMR imaging clearly distinguished pericardial from pleural effusions. NMR imaging is indicated when a suspected pericardial effusions is not detected by echocardiography or when specific localization or fluid characterization is desired.     

Balloon valvuloplasty for pulmonic valve stenosis--two-year follow-up: hemodynamic and Doppler evaluation

The purpose of this investigation was to evaluate the efficacy, technique, and follow-up results of balloon dilation angioplasty for valvular pulmonary stenosis. Percutaneous dilation was performed on 63 patients with pulmonary stenosis (ages 3 months to 76 years, mean = 4.3 years). In 43 patients, a single balloon was used; in 20 patients two balloons were used simultaneously. The pressure gradient across the pulmonary valve was determined with right ventricular and main pulmonary artery catheters. Pressure gradients simultaneously were estimated by continuous wave Doppler (CWD) during catheterization. The peak systolic ejection gradient was obtained by both techniques both pre- and postangioplasty. There was excellent linear correlation between the simultaneous catheter pressure gradient and the pressure gradient estimated by Doppler (r = 0.99). Follow-up pressure gradient estimations by Doppler echocardiogram were obtained in 30 patients between 6 months and 30 months postcatheterization (mean = 13 months). The mean preangioplasty gradient of 64 mm Hg (range 30-160 mm Hg) was reduced to 22 mm Hg (range 2-31 mm Hg). A significant reduction of transvalvular gradient (52-95%, mean 68%) occurred in each patient. A linear correlation was found between the predilation gradient and the pressure gradient drop (r = 0.92). Mean follow-up gradient by Doppler was 20 mm Hg (range 0-31 mm Hg), and there was no significant difference between these gradients and the postdilation gradient. No important complications were noted. These data confirm that balloon dilation angioplasty for valvular pulmonary stenosis is safe and effective, and suggest that stenosis does not recur.     

Balloon valvuloplasty for pulmonic valve stenosis—two-year follow-up: Hemodynamic and doppler evaluation

The purpose of this investigation was to evaluate the efficacy, technique, and follow-up results of balloon dilation angioplasty for valvular pulmonary stenosis. Percutaneous dilation was performed on 63 patients with pulmonary stenosis (ages 3 months to 76 years, mean = 4.3 years). In 43 patients, a single balloon was used; in 20 patients two balloons were used simultaneously. The pressure gradient across the pulmonary valve was determined with right ventricular and main pulmonary artery catheters. Pressure gradients simultaneously were estimated by continuous wave Doppler (CWD) during catheterization. The peak systolic ejection gradient was obtained by both techniques both pre- and postangioplasty. There was excellent linear correlation between the simultaneous catheter pressure gradient and the pressure gradient estimated by Doppler (r = 0.99). Follow-up pressure gradient estimations by Doppler echocardiogram were obtained in 30 patients between 6 months and 30 months postcatheterization (mean = 13 months). The mean preangioplasty gradient of 64 mm Hg (range 30–160 mm Hg) was reduced to 22 mm Hg (range 2–31 mm Hg). A significant reduction of transvalvular gradient (52–95%, mean 68%) occurred in each patient. A linear correlation was found between the predilation gradient and the pressure gradient drop (r = 0.92). Mean follow-up gradient by Doppler was 20 mm Hg (range 0–31 mm Hg), and there was no significant difference between these gradients and the postdilation gradient. No important complications were noted. These data confirm that balloon dilation angioplasty for valvular pulmonary stenosis is safe and effective, and suggest that stenosis does not recur.     

Heterogeneity in anticatalytic activity of antibody specific for horseradish peroxidase

Rabbit antibodies specific for horseradish peroxidase are heterogeneous in their ability to inhibit enzyme activity. Heterogeneity was demonstrated by fractionation of the total antiperoxidase pool by differential ammonium sulfate precipitation and differential elution of antibody from enzyme affinity columns. Both fractionation methods yielded antibody subpopulations that differed in anticatalytic activity. Some antibody subpopulations decreased enzyme activity almost completely at low molar ratios of antibody to peroxidase. Other subpopulations were not effective inhibitors even at great molar excess. Admixture experiments demonstrated that inefficient antibody pools decreased the anticatalytic effect of highly inhibitory antibody. The degree of inhibition observed with unfractionated antiserum is a reflection of the interaction of various antibody subpopulations with the enzyme. No correlation was found between the immunoglobulin class of antiperoxidase and anticatalytic efficiency in analyses of numerous antisera. The determinant specificity of an antiperoxidase molecule determines its anticatalytic ability. A peptide fragment (mol. wt 22,500) of peroxidase prepared by partial tryptic digestion bount 60 to 70% of the total antiperoxidase in a number of antisera. However, the peptide did not bind inhibitory antibodies.     

Kindling produces long-lasting and selective changes in gene expression of hippocampal neurons.

To test the hypothesis that repeated subconvulsive stimulations required to induce kindling can permanently alter gene expression of hippocampal neurons, we used Northern and in situ hybridization analyses to measure steady-state mRNA levels encoding several phenotypic proteins. mRNA encoding a membrane-bound protein, ligatin, was significantly reduced in kindled brains relative to naive and sham control animals. This change in gene expression persisted for over 4 months after kindling, was associated with a decrease in ligatin protein expression, was not produced by single or multiple seizures that did not induce the kindling phenomena, and was blocked by MK801. These results provide direct evidence that kindling can cause persistent changes in the expression of specific genes in hippocampal neurons and suggest that N-methyl-D-aspartate receptor-activated changes in gene expression may be a basic molecular mechanism underlying some of the long-lasting plasticity changes seen in kindling or models of long-term memory.     

Implantation of balloon-expandable intravascular grafts by catheterization in pulmonary arteries and systemic veins

The purpose of this investigation was to evaluate the efficacy and safety of implanting expandable intravascular stents in pulmonary arteries and systemic veins. Twenty-seven balloon-expandable grafts were placed in 13 mongrel dogs under anesthesia. A long sheath was introduced over a wire and catheter or dilator into the pulmonary artery or target vein. A collapsed stainless steel expandable mesh stent was placed over the balloon of an angioplasty catheter. The catheter with the mounted stent was advanced through the sheath. The stent expanded to the diameter of the balloon as the balloon was inflated, and remained expanded as the balloon was deflated. The stent was expanded further with a larger balloon in 11 instances. Eleven stents were placed successfully in pulmonary arteries (out of thirteen attempted), and 11 of 14 were installed in tributaries of the precava or postcava. Three inadvertent embolizations of the devices occurred. All three devices that embolized lodged in the pulmonary arteries and did not obstruct flow. Seven dogs were recatheterized at intervals ranging from 56 to 278 days. Twelve stents were patent and nonobstructive, and two were malpositioned, one of which was obstructed. Three animals were killed 2 months (two dogs) and 9 months (one dog) after the implantations. The stents (four in the pulmonary arteries and two in veins) were completely covered with neointima and were patent, without thrombosis. These stents hold promise for definitive dilation of congenital or postoperative vessel stenoses.     

See One,Do One,Be Competent in One? Resident Rotations Broaden the Perceived Scope of General Surgery

PURPOSE: To compare the scope of general surgery as perceived by general surgery program directors (PDs) nationally and our residents (RES), and to assess the effect of clinical rotation assignments on resident perception. METHODS: A background questionnaire and survey document drawn from the Resident Operative Report submitted by finishing residents to the American Board of Surgery (ABS) was sent to our general surgery residents. Respondents categorized 309 items as procedures with which a finishing resident should be competent (A), familiar (B), or neither (C). Data from an identical survey of PDs were obtained from the ABS. Procedures were assigned to Groups 1-4 based on resident rotations. PD responses were considered the reference data set. RES answers outside the range of 0.5x to 1.5x, where x = PD% for each item, were labeled as different. Differences were categorized as residents having a "narrower" perception of general surgery if RES %A less than 0.5x and %C greater than 1.5x and "broader" if RES %A greater than 1.5x and %C less than 0.5x. Chi-square testing was also performed as a "cross-check" analysis. RESULTS: After eliminating consensus items, 60 Group 1 items, 103 in Group 2, 19 in Group 3, and 16 in Group 4 remained. When linked to resident rotations, RES took a broader view of general surgery scope for 27/163 items and a narrower view for only 1 item (0.6%). Without related rotation experience, RES viewed 0/19 procedures more broadly than PD and categorized 7/19 items more narrowly. When items overlapped 2 surgical specialties, RES assigned no items as broader or narrower. Chi-square testing produced similar results. CONCLUSION: Our residents perceived the scope of general surgery more broadly than did a national sample of PDs for content areas in which residents completed rotations. A broader view of general surgery could influence resident decision making about postresidency fellowships.     

Gastric electrical stimulation for children with intractable nausea and gastroparesis

Purpose

Gastric electrical stimulation (GES) has been performed in adults as a treatment of refractory nausea and vomiting in patients who have failed medical treatment, but has not been used in children.

Methods

Nine patients with chronic nausea and vomiting with a mean age of 14 years were evaluated for temporary GES. All 9 patients subsequently underwent placement of a temporary followed by permanent GES device. Symptoms were recorded at baseline, after temporary GES, and then after permanent GES using a Likert scale for gastroparesis. Statistical analysis was performed using a paired Student's t test.

Results

At baseline, all patients were symptomatic and most had delayed solid gastric emptying. As a group, there was a significant improvement in combined symptoms score (P = .04), nausea (P = .039), and vomiting (P = .0016). Gastric emptying and electrogastrogram values did not change significantly. Follow-up ranged from 8 to 42 months, with 7 of the 9 patients reporting sustained improvement in symptoms and improved quality of life.

Conclusions

Gastric electrical stimulation can be successfully applied to adolescents with intractable nausea and gastroparesis symptoms who fail medical therapy. There is a significant improvement in symptoms over a prolonged period ,and there are no adverse effects of the GES. Long-term efficacy of this therapy in children needs to be established.     

The 'natural' growth hormone explosion: fact or fraud?

Since the past decade there has been a rapidly growing market of natural growth hormone (GH) products based on clinical trials carried out on GH-deficient persons, using the injectable hormone, which is the FDA-approved form. Prior medical publications on the benefits of GH replacement brought about an exaggerated interest on the use of this hormone as a dietary supplement for rejuvenating purposes. This has led to the uncontrolled proliferation of all kinds of GH products advertised irresponsibly as if having extraordinary age-reversing properties without the necessary clinical trials to prove their effectiveness and safety. This review summarizes the circumstances which led to this excitement over GH therapy and provides an overview of the different types and forms in which these natural GH products are sold, giving emphasis on the possible misleading advertisements and the lack of reliable proof to their claims.