Biomedical subjects
Publications and source records attributed to L Gerber.
A case of left ventricular perforation by straight-tipped balloon catheter during double-balloon mitral valvuloplasty with fatal outcome is presented. Technical considerations to prevent this complication are discussed.
Alkaline phosphatase is anchored to the plasma membrane by a carboxyl-terminal phosphatidylinositol glycan moiety. To investigate the biosynthesis of mature alkaline phosphatase, nascent human placental alkaline phosphatase was expressed in a cell-free system and used as substrate for in vitro processing by microsomal extracts. By monitoring the processed product with three site-directed antibodies, it was shown that microsomal extracts from CHO cells that contain other recognized processing activities also remove the carboxyl-terminal signal peptide from the preproenzyme in an apparently selective manner. This peptidase-like cleavage may be brought about by the action of a specific transamidase acting on the nascent protein in the absence of an appropriate phosphatidylinositol glycan cosubstrate.
Meeting minutes of Section 501(c)(3) organizations are one of the first places the Internal Revenue Service, the state attorney general, and others will look in trying to determine whether the board of directors is governing the corporation's operations and activities in conformance with tax-exemption rules and whether board members are properly fulfilling their corporate fiduciary duties. Because such minutes reflect deliberations and actions that took place at board meetings, minutes provide a record of circumstances surrounding significant corporate decisions--decisions the IRS and others may choose to question. An organization trying to maintain its tax-exempt status can further its cause by making sure that meeting discussions (and minutes), as well as backup documentation, include all pertinent information. The tax-exempt organization should take special care when drafting minutes regarding deliberations and actions pertaining to transactions that prompt close IRS scrutiny. For example, with joint ventures, corporate minutes should reflect that the exempt organization's board based its decision to enter into the joint venture primarily on the venture's investment value and/or its value in achieving exempt purposes--not the venture's benefit to the non-exempt party.
In our first 80 attempts of percutaneous double balloon mitral valvuloplasty (BMV) 77 procedures have been successful. The mean patients age was 44 +/- 17 years, there were 16 men; 12 patients had previously been operated, 29 patients had important valvular deterioration (calcifications, thickening or unpliability) or of subvalvar system. For technical failure BMV was performed with only one balloon in 8 patients. BMV resulted in significant improvement in haemodynamic values: the mean capillary pressure fell from 22 +/- 6 to 12 +/- 5 mmHg (p less than 0.001), the mean mitral gradient from 15 +/- 6 to 5 +/- 3 mmHg (p less than 0.001). Cardiac index remained unchanged. The hemodynamic valve area, by Gorlin formula, increased from 1.09 +/- 0.29 to 2.19 +/- 0.72 cm2 (p less than 0.001). Doppler and echocardiography data were similar to haemodynamic data. Mitral valve area obtained with BMV was equivalent to the area usually obtained in closed mitral commissurotomy. There were 3 tamponades. The first, in a patient to whom BMV was not successful. For the 2 others, surgically evacuated, intracavitary pressures were measured after surgical pericardial drain. BMV was of little efficacy in one patient who died 3 days thoracotomy. The three tamponades were caused by straight tip balloon left ventricle perforation. There was no tamponade with pigtail tip catheter balloon. Mitral valve regurgitation was never increased more than 1 + Interatrial septal defect with QP/QS greater than or equal to 1.5 and less than 2 was present in 5 patients. BMV may be a useful alternative to surgery with low incidence of complication. Mitral valve area increase is similar with both treatment.
Dynamic configurational changes in the rectus femoris muscle were examined using a real time ultrasound sector scanner in ten normal subjects. The angle of passive knee flexion was varied as transverse ultrasound scanning was performed at the mid-transverse thigh. Configurational changes in the rectus femoris were computed from a traced outline of the muscle and the geometric center of the mass was calculated at all degrees of knee flexion. The geometric center of the mass varied with knee position. The anterioposterior dimensions and cross sectional areas of the rectus femoris and vastus intermedius remained constant, however, despite changes in knee position. The pattern of change observed was reproducible and reflects consistent changes in muscle configuration. The technique and instrumentation should have value for non-invasive dynamic and static observation of individual muscles.
Placental alkaline phosphatase (PLAP) is anchored to the plasma membrane by a phosphatidylinositol-glycan (PI-G) moiety. During processing of nascent PLAP, a 29-residue COOH-terminal peptide is cleaved out and the PI-G moiety is attached to the newly created COOH terminus of the mature protein. To investigate the structural requirements of the COOH terminus of the nascent protein for PI-G tailing and anchoring to the plasma membrane, we have transfected COS cells with wild type and mutant forms of cDNA encoding human prepro-PLAP. Utilizing a series of COOH-terminal deletion mutants of prepro-PLAP, it was found that to be PI-G-tailed the newly synthesized protein must possess an uncharged, predominantly hydrophobic amino acid sequence of a minimal length in the COOH-terminal peptide. While forms of prepro-PLAP with 17 consecutive hydrophobic residues in the terminal sequence yielded PI-G-tailed and membrane-bound products, prepro-PLAP mutants with 13 or fewer of such residues yielded hydrophilic proteins that were no longer PI-G-tailed but efficiently secreted into the medium. Studies using cassette mutants demonstrated that the precise amino sequence of the COOH-terminal region could be altered as long as minimal hydrophobicity and length was maintained.
An immunological approach to the study of the structure and biogenesis of the phosphatidylinositol glycan (PI-G) membrane anchor at the carboxyl terminus of human placental alkaline phosphatase (PLAP) is described. Based on the protein sequence predicted from full length PLAP cDNA, two epitopes were chosen in the region of the carboxyl terminus for the production of site-directed antibodies. The exo site represents the last nine residues of preproPLAP, (res. 505-513), which is part of the sequence that is expected to be cleaved from the nascent protein during processing and addition of the PI-G tail. A second site, the endo sequence, was selected close to the expected carboxyl terminus in mature PI-G-tailed PLAP (res. 474-484 of proPLAP). The two peptides were synthesized, polyclonal antibodies to the conjugated peptides were prepared, and the antisera were characterized. Analytical methods for both synthetic peptides and proteins are presented. Preliminary applications to the isolation and characterization of the PI-G-linked carboxyl terminus of mature PLAP and to the characterization of nascent PLAP are described. The application of both carboxyl terminal-directed antibodies, and a third antibody directed to the amino terminus of mature PLAP, in studies employing mutant forms of PLAP and to the PI-G tailing process itself are discussed. The immunological approach used here for PLAP should be applicable generally to the study of other PI-G-tailed proteins.
A carboxyl-terminal chymotryptic peptide from mature human placental alkaline phosphatase was purified by HPLC and monitored by a specific RIA. Sequencing and amino acid assay showed that the carboxyl terminus of the peptide was aspartic acid, representing residue 484 of the proenzyme as deduced from the corresponding cDNA. Further analysis of the peptide showed it to be a peptidoglycan containing one residue of ethanolamine, one residue of glucosamine, and two residues of neutral hexose. The inositol glycan is apparently linked to the alpha carboxyl group of the aspartic acid through the ethanolamine. Location of the inositol glycan on Asp-484 of the proenzyme indicates that a 29-residue peptide is cleaved from the nascent protein during the post-translational condensation with the phosphatidylinositol-glycan.
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The possible role in vivo of osseous structures in binding radioactive iron injected as a low-molecular-weight complex was studied in mice, using combined autoradiography and histomorphometry on sections of undecalcified, plastic-embedded femur epiphyses/metaphyses. A single intraperitoneal injection of 10 microCi 59Fe (1.2 micrograms Fe) per animal as citrate within 3 hours led to a preferential accumulation of this metal in the osteoid mineralized tissue interphase (osteoid seams) of bone. Within the next 2 days the labeling intensity in this localization diminished markedly to approximate levels of the bone marrow and calcified bone. The bulk of the injected radioiron was utilized according to known erythrokinetics. Findings suggest a direct entry of "free," ie, not transferrin-bound, iron into osteoid seams and its consecutive rapid removal from this site.
Scintillation proximity assay (SPA) makes it possible to use radioisotopes for monitoring binding reactions continuously without the need to separate free from bound components. As a result SPA can be carried out more rapidly than most other methods used to monitor binding reactions. The methodology also lends itself to automation. The sensitivities already achieved with SPA procedures are comparable to the sensitivities of other procedures in use today. Another feature of SPA is that the key reagents (beads, 125I labeling) are relatively inexpensive. The principles of SPA, utilizing 125I-labeled molecules, are discussed and some applications to immunology, receptor binding, and measurement of potential across membranes are presented. SPA should also be applicable to monitoring interactions involving nucleic acids, lipids, and carbohydrates. Characteristics of some radionuclides, other than tritium and 125I, that may be used in SPA are presented.
Human placental alkaline phosphatase (PALPase) has been transiently expressed in simian (COS) cells by transfection with a eukaryotic expression vector containing the corresponding cDNA. The level of expression of PALPase was high, and it was produced in an enzymatically active form. The bulk of PALPase was associated with the cell membrane as shown by immunocytochemistry and subcellular fractionation studies. The PALPase produced by transfected COS cells, like PALPase in human tissue, was specifically released from the intact cells in a hydrophilic form by phosphatidylinositol-specific phospholipase C and is, therefore, apparently attached to the outer membrane by means of a phosphatidylinositol-glycan. Transfected COS cells appear to be an excellent model for elucidating the mechanism of attachment of this phosphatidylinositol-glycan to a protein moiety.
Placental alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] is a member of a diverse group of membrane proteins whose attachment to the lipid bilayer is mediated by a phosphatidylinositol-glycan. To investigate structural aspects of the glycolipid anchor, cultured WISH cells were used because we found that they produce the enzyme in abundant quantities. When cell suspensions were incubated with purified phosphatidylinositol-specific phospholipase C, most of the placental alkaline phosphatase was released from membranes in a hydrophilic form. On incubation of the cells with [14C]ethanolamine, [14C]myristic acid, or myo-[3H]inositol, each was incorporated into the phosphatase near the carboxyl terminus, showing that these components, which are found in other phosphatidylinositol membrane-linked proteins, are also present in placental alkaline phosphatase.
Cyclic AMP phosphodiesterase (PDE; EC 3.1.4.17) in Thermomonospora curvata was purified and characterized. Fractionation of cell extracts by ion-exchange and size-exclusion chromatography revealed four PDE isozymes, which differed markedly in molecular weight, theophylline sensitivity, pH optima, and substrate affinity. Although the enzyme was labile after purification, total recovery of PDE activity was fivefold that of the crude extract. PDE biosynthesis appeared sensitive to the growth phase, growth rate, and carbon source. PDE levels in batch cultures peaked and declined rapidly during mid-exponential-phase growth. In continuous culture, maximal PDE and cellulase production occurred at dilution rates yielding mean cell generation times of about 5 and 17 h, respectively. The addition of glucose to cellulose-grown cells caused declines in both cyclic AMP and PDE levels, suggesting that the enzyme was subject to, rather than the agent of, catabolite repression.
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We report a prospective, randomized pilot study comparing a new workbook-based program, designed to teach patients with rheumatoid arthritis (RA) energy conservation behaviors, with standard occupational therapy (OT). Sixteen patients took part in the new program and nine received the standard therapy. Data on the number of tender or swollen joints, grip strength, walk time, activities of daily living, psychologic adjustment to illness, and daily activity log, were measured before and three months after intervention. Eleven percent of those who received standard therapy and 50% of those who received the workbook increased their amount of physically active time (p = .10). Twenty-two percent of the control group and 50% of those in the workbook group achieved a better balance of rest and physical activity (p = .07). We conclude that the adoption of energy conservation behaviors is different in the two groups. This initial study suggests that interrupting physical activity with rest periods may result in increased physical activity in patients with RA.
The fact that the term "joint venture" has become a buzz word in the hospital industry should not be allowed to obscure two basic facts. First, the concept is quite complex, involving tax and securities law issues as well as a number of important operational, financial, and governance issues. Second, the concept is an important one for the future of many hospitals. This article examines the misconceptions surrounding joint ventures and presents examples of actual joint ventures that hospitals have participated in, from physicians office building to home health agencies.
Amrinone, a new inotropic agent, was used to treat 24 patients with chronic congestive heart failure who were classified as clinically stable and who were in New York Heart Association's classes II and III. Patients were treated for up to 30 months (mean, 12.5 months). Exercise tolerance improved in 20 patients, but only eight experienced significant improvement in symptoms of fatigue, dyspnea, and orthopnea and only nine tolerated the drug without apparent side effects. Eight were unable to continue amrinone therapy because of limiting side effects. The most significant adverse effects were cardiac arrhythmias, thrombocytopenia, abnormal results of liver function tests, diarrhea, fever, and nausea. Amrinone has a narrow therapeutic-toxic ratio, but a significant proportion (42%) of patients tolerate and benefit from amrinone therapy.