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Biomedical subjects

E R Schmid

Publications and source records attributed to E R Schmid.

At least 19 recordsLinked to original sources
PubMed1992

The complete primary structure of the boar spermadhesin AQN-1, a carbohydrate-binding protein involved in fertilization.

Gamete recognition and adhesion are essential steps in the complex process of fertilization. In mammals and in other species, increasing evidence indicates that carbohydrate-binding proteins on the sperm surface play a pivotal role as counter-receptors for certain oligosaccharide moieties attached to the oocyte zona pellucida glycoproteins. Although different sperm-associated zona-pellucida-binding proteins have been identified in a number of species, few of them have been isolated and structurally characterized. In this paper we report the primary structural characterization of AQN-1, a 12-kDa boar-sperm-associated carbohydrate-binding and zona-pellucida-binding protein. The molecular mass of AQN-1 was determined by time-of-flight plasma-desorption mass spectrometry. Determination of its amino acid sequence and location of disulphide bridges were accomplished by a combination of proteochemical and mass spectrometric methods. The primary structure of AQN-1 failed to show any significant similarity to the protein structures deposited with the Martinsried Institute for Protein Sequences data bank, indicating that it may belong to a novel protein family involved in fertilization. AQN-1 shares extensive structural, as well as functional, similarity with two other boar sperm zona-pellucida-binding proteins, AQN-3 and AWN, which we have recently characterized. To name this protein family, we have coined the term spermadhesin. Our data may be relevant for identification of spermadhesins in other species, and thus may contribute to a better understanding of the species-specific sperm-egg recognition mechanism.

Amino Acid Sequence↗
PubMed1992

The complete primary structure of the spermadhesin AWN, a zona pellucida-binding protein isolated from boar spermatozoa.

AWN is a boar protein which originates in secretions of the male accessory glands and which becomes sperm surface-associated upon ejaculation. It is one of the components thought to mediate sperm adhesion to the egg's zona pellucida through a carbohydrate-recognition mechanism. AWN may, thus, participate in the initial events of fertilization in the pig. In this report we describe its complete primary structure by combination of protein-chemical and mass spectrometric methods. AWN exists as two isoforms, AWN-1 and AWN-2, which differ in that AWN-2 is N-terminally acetylated. The amino acid sequence of AWN contains 133 amino acid residues and two disulphide bridges between nearest-neighbour cysteine residues. Analysis of the amino acid sequence of the AWN proteins showed significant similarity only to AQN-1 and AQN-3, two other boar spermadhesins.

Amino Acid Sequence↗
PubMed1992

The complete primary structure of three isoforms of a boar sperm-associated acrosin inhibitor.

Acrosin inhibitors of seminal vesicle origin, after binding to their acceptor molecules on the anterior part of ejaculated sperm, are thought to be important capacitation factors, protecting zona binding sites during sperm uterine passage, and then dissociating to allow sperm binding to the zona pellucida of the oocyte. Each species so far tested possess an heterogeneous population of isoinhibitors which may display overlapping but not identical biological functions. Here we report the complete primary structure of three isoforms of a boar sperm-associated acrosin inhibitor, whose sequences are 90% identical to the seminal plasma counterpart. Despite this high analogy, the differences between the sperm-associated and the seminal plasma inhibitors may confer to them different physico-chemical properties which are postulated to be of functional importance.

Acrosin↗
PubMed1992

Gas transport during high-frequency ventilation: the significance of direct wash-out.

Gas transport during high-frequency oscillation was investigated in vitro using CO2 elimination from the lung surrogate as a measure of gas transport efficiency. The length of the connecting tube between the piston pump and the three-port connector did not affect gas transport efficiency if the oscillatory volume (VDEL) was constant; inserting an additional tube between the three-port connector and the endotracheal tube decreased gas transport efficiency dramatically. In contradistinction, increasing VDEL caused a steep rise in gas transport efficiency as soon as VDEL surpassed the volume of the tubes connecting the lung surrogate with its surroundings. As gas transport efficiency was found to be very sensitive to the net oscillatory volume, i.e. VDEL minus the volume of the tubes connecting the lung and the surroundings, direct wash-out was considered to be an effective gas transport mechanism during high frequency oscillation. Two preliminary experiments on dogs allowed us to substantiate this hypothesis in vivo.

Animals↗
PubMed1991

The amino acid sequence of AQN-3, a carbohydrate-binding protein isolated from boar sperm. Location of disulphide bridges.

Gamete recognition and adhesion are essential steps in fertilization. Among others, carbohydrate-binding proteins on the sperm surface have been recognized to play a central role in the initial interaction of the male gamete with components of the zona pellucida of the homologous investing oocyte. We have isolated several members of a carbohydrate- and zona pellucida-binding protein family from ejaculated sperm. Here we report the biological origin and structural characterization of AQN-3, a component of this carbohydrate-binding family. The molecular weight of purified AQN-3 was determined by plasma desorption mass spectrometry. The protein was chemically and enzymatically degraded, the proteolytic fragments isolated and characterized by N-terminal sequencing and fast atom bombardment mass spectrometry. In this manner we established the complete amino acid sequence of AQN-3 and the location of its two disulphide bonds. No analogous protein sequence could be found in the MIPS protein sequence data bank, indicating that AQN-3 may belong to a novel mammalian carbohydrate-binding protein family.

Amino Acid Sequence↗
PubMed1991

[Successful resection of a hypernephroma extending continuously into the right ventricle: utilization of extracorporeal circulation in general surgery].

We report the case of a 53-year-old woman with renal cell carcinoma extending into the inferior vena cava and through the tricuspid valve into the right ventricle. Successful total removal was performed with the aid of cardiopulmonary bypass. The rarity of this case prompted a review of the literature in which only the involvement of right atrium in this type of tumor was found. Review of our own experience with extracorporal circulation in non-cardiac procedures demonstrates that an aggressive therapeutic approach, requiring operations of escalating magnitude and multidisciplinary surgical treatment, can salvage patients who otherwise might not be considered for operation.

Carcinoma, Renal Cell↗
PubMed1991

Characterization of phosphatidylcholines in rabbit lung lavage fluid by positive and negative ion fast-atom bombardment mass spectrometry.

The relative distribution of intact diacylphosphatidylcholine species isolated from the lung lavage fluid of rabbits has been investigated by positive ion fast-atom bombardment (FAB) mass spectrometry. Two different isolation/purification methods were applied and evaluated prior to mass spectrometric analysis. The first method consisted of a Bligh and Dyer extraction of the lung lavage fluid followed by isocratic high-performance liquid chromatographic (HPLC) separation. In the second method a thin-layer chromatographic purification step was introduced between the extraction procedure and the HPLC separation. Further, the FAB matrices glycerol and 3-nitrobenzyl alcohol were used, and their influence on the diacylphosphatidylcholine molecular ion species was studied. The Bligh and Dyer extraction followed by the simple HPLC separation was the method of choice to obtain stable, long-lasting protonated molecular ions and diagnostic fragment ions, which permitted the identification of the polar head-group. In combination with 3-nitrobenzyl alcohol as liquid matrix we established a procedure that yielded a fast sample preparation method, a good signal-to-noise ratio for detecting minor species, and reduced formation of [M+H-2H]+ ion species. The relative fatty acid composition of the diacylphosphatidylcholine fractions isolated from rabbit lung lavage fluid was determined by negative ion FAB mass spectrometry using the carboxylate anions. The mass spectrometric results were compared with those acquired by gas chromatographic determination of the fatty acid methyl esters. Close agreement was found between the data obtained by the two independent methods.

Animals↗
PubMed1991

Significance of bulk convection during high-frequency oscillation.

In 7 anesthetized supine dogs with an anatomic dead space of 115-162 ml, gas transport during high-frequency oscillation (HFO) was investigated at an oscillatory frequency of 15 Hz. Starting with an oscillatory volume effectively delivered to the lungs (VDEL) of 60 ml, measured on line with an ultrasonic airflow meter, VDEL was reduced in steps of 10 ml, down to a VDEL of 30 ml, whereby fresh gas flow rate, airway occlusion pressure and lung volume above functional residual capacity were kept constant. An HFO-circuit without bias tube was used. The volume of endotracheal tube and three port connector, designated as HFO-circuit related rebreathing volume, was 35 ml. PaCO2 continuously increased, when VDEL was reduced from 60 ml to 40 ml and the data fit perfectly to a reciprocal regression (1/PaCO2 = a + b.VDEL), r2 ranging from 0.95 to 1.00. Measured PaCO2 values at a VDEL of 30 ml (8.26 +/- 1.77 kPa), however, were significantly (P less than 0.025) higher than PaCO2 values predicted by the individual reciprocal regression equations (6.25 +/- 1.46 kPa). This overproportionate increase in PaCO2 due to a reduction of VDEL from 40 ml to 30 ml may be explained by the sudden drop out of bulk convection as a gas transport mechanism between central airways and the surrounding because bulk convection is only possible as long as VDEL exceeds the HFO-circuit related rebreathing volume. Bulk convection therefore is considered an essential gas transport mechanism during HFO and the efficiency of CO2 elimination during HFO is critically dependent on the net oscillatory volume, i.e. VDEL minus the HFO-circuit related rebreathing volume and not on the relationship between VDEL and anatomic dead space.

Animals↗
PubMed1991

Preoperative assessment of the likelihood of infection of the lower respiratory tract after cardiac surgery.

Lower-respiratory-tract infections are among the most frequent complications observed in the intensive care unit, leading to delayed postoperative recovery time and increased costs and mortality. We have tried to evaluate the prognostic value of perioperative bacteriology of tracheal aspirates in assessing the risk of such complications. In a prospective study aspirates of 100 patients undergoing cardiac surgery were taken immediately after intubation and were analysed for microorganisms by Gram-stain and microbiological cultures using standard procedures. All patients received perioperative antibiotic prophylaxis with a single dose of 2 g ceftriaxone intravenously. From 26 patients with bacteriologically positive tracheal secretion, 8 (30.7%) developed lower respiratory tract infection whereas only 1 of 72 patients (1.4%) with negative bacteriological results developed this complication. Smoking (p less than 0.01) and abnormal preoperative lung function (p less than 0.01) were significantly more frequent in patients developing postoperative pneumonia. Regarding the results of this study, the risk of developing pulmonary infection in the early postoperative course after cardiac surgery can be estimated from the tracheal aspirates.

Adult↗
PubMed1991

Comparison of nalbuphine and fentanyl anesthesia for coronary artery bypass surgery. Hemodynamics, hormonal response, and postoperative respiratory depression.

To determine whether nalbuphine might replace fentanyl as the principal opioid for anesthesia during coronary artery bypass surgery, 20 patients undergoing myocardial revascularization were anesthetized with flunitrazepam and with a continuous infusion of either nalbuphine (an opioid agonist-antagonist) or fentanyl (a pure opioid agonist) in equipotent dosage ratio of 333:1. During endotracheal intubation, all patients given nalbuphine, but only one given fentanyl (P less than 0.05), required nitroglycerin to control arterial blood pressure. Two minutes after tracheal intubation, plasma values of epinephrine, norepinephrine, vasopressin, and cortisol did not change in the fentanyl group compared with the awake (baseline) levels, whereas catecholamines and vasopressin significantly increased with nalbuphine compared with the baseline and with the values in the fentanyl group. A steady state of anesthesia (30 min after intubation), when compared with the baseline, was characterized by unchanged systemic and pulmonary blood pressures and increased systemic vascular resistance with nalbuphine, by decreased systemic and pulmonary pressures and resistances with fentanyl, and by comparably decreased cardiac index with both opioids. Hormone values returned to baseline levels but norepinephrine remained significantly higher in the nalbuphine than in the fentanyl group. A bolus injection of either nalbuphine (2.5 mg/kg) or fentanyl (7.5 micrograms/kg) given during the steady-state period of anesthesia provoked only minimal hemodynamic changes. Before skin incision, 7 of 10 patients receiving nalbuphine required nitroglycerin to control arterial blood pressure. After sternotomy, both groups required nitroglycerin, but additional antihypertensive drugs were necessary mainly in the nalbuphine group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗
PubMed1991

[Cardiac risk patients in anesthesia].

Cardiac complications are the major cause of morbidity and mortality in patients undergoing noncardiac operations. The perioperative risk of adverse cardiac events is particularly high in patients with significant coronary artery disease, heart failure or critical aortic stenosis. Prolonged intraperitoneal and intrathoracic operations, major vascular surgery, emergency procedures, and intraoperative hypotension and tachycardia promote and increase incidence and severity of cardiac complications. Recent experience has shown, however, that elective noncardiac operations can be performed with justifiable risk even in patients with endstage cardiac disease awaiting heart transplantation. Surgery, if indicated, can thus nowadays hardly be denied even in the presence of high cardiac risk. Successful anesthetic management requires detailed information about the cause and severity of the underlying disease, thorough understanding of its specific hemodynamic particularities, indepth knowledge about hemodynamic effects and interactions of anesthetic drugs, and experience with extended hemodynamic monitoring. Anesthetic choice by itself appears to be of minor significance. Cardiac surgery prior to major elective noncardiac procedures is advocated in patients with significant coronary artery disease or severe valve lesions. The incidence of life-threatening cardiac complications is particularly high in the postoperative period; prolonged hemodynamic monitoring in an intensive care unit is therefore mandatory.

Anesthesia↗
PubMed1991

[Blood transfusion and reducing the need for blood in heart transplantation].

Viral infections transmitted by the donor organ or by blood and blood products are severe complications in heart transplantation. The use of blood and blood saving management is evaluated in 57 consecutive orthotopic heart transplantations. Indication was cardiomyopathy in 63%, coronary artery disease in 30%, valve disease in 5%, congenital in 5%, arrhythmia in 5% and primary cardiac malignancy in 2%. Previous open heart surgery was performed in 32%, and 81% had anticoagulation, with a mean quick value of 0.28 +/- 0.13. The total use of blood and blood products was 1151 units and was distributed as follows: whole blood and packed cells 41%, platelets 17%, fresh frozen plasma (FFP) and coagulation factors 36%, albumine 7%. Anticoagulated recipients received more FFP and factors, 7.9 +/- 5.7 U vs. 4.4 +/- 4.8 U. In the reoperation group 78% vs. 22% (p less than 0.001) in the primary operation group received platelets. Hemodilution to hematocrit 0.24 instead of 0.30 lead to a decrease of red cell transfusions per patient from 12.3 +/- 6.7 U to 6.3 +/- 7.4 U (p less than 0.001) and the percentage of patients receiving red cells was reduced from 100% to 82%. Intraoperative hemofiltration was performed in 49% (mean filtration volume was 1652 +/- 910 ml). No differences in the amount of blood and blood products could be shown. Heart transplantation is an operation with a high need for blood and blood products. Reoperation and anticoagulation are predictors for a higher use of platelets, FFP and coagulation factors. Hemodilution reduces the use of red cells, whereas intraoperative hemofiltration has no influence on the use of blood.

Adolescent↗
PubMed1991

Fatal fungal pericarditis after cardiac surgery and immunosuppression.

The cases of two patients with fulminant pericarditis after cardiac surgery are reported. Both fungal infections developed after rethoracotomy for open-chest cardiac resuscitation and high-dose glucocorticoid treatment. Although the time course of both infections from the inoculation of fungi during rethoracotomy and immunosuppression with glucocorticoids to the lethal outcome was strikingly similar, histopathologic studies disclosed the disparate character of the two fungal pathogens responsible: the yeast Candida albicans and the angiotropic mold Aspergillus fumigatus.

Aged↗