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Biomedical subjects

J Klein

Publications and source records attributed to J Klein.

At least 667 records · Page 37Linked to original sources
PubMed1986

Fentanyl-oxygen versus fentanyl-N2O/oxygen anaesthesia in children undergoing cardiac surgery.

Fentanyl-oxygen (fentanyl-O2) anaesthesia was compared to fentanyl-nitrous oxide/oxygen (fentanyl-N2O/O2) anaesthesia in 14 children undergoing cardiac surgery. Children were randomly assigned to one of the two techniques studied, with seven patients in each group. The mean age (mean +/- SE) was 3.9 +/- 0.75 years (0.5-8.25 years) and mean weight 14.7 +/- 2 kg (3.5-29.5 kg). Patients were premedicated with IM atropine 0.02 mg . kg-1 and morphine 0.2 mg . kg-1 1 hour preoperatively. They received a fentanyl bolus of 30 micrograms . kg-1 with a concomitant continuous infusion of 0.3 micrograms . kg-1 . min-1. Pancuronium 0.1 mg . kg-1 was administered immediately following the fentanyl bolus. Fifty per cent nitrous oxide was given with oxygen in one group and 100 per cent oxygen was administered to the other group. Fentanyl plasma concentrations were similar in the two groups at the various stages of surgery. There were no significant differences between the two treatment groups in systolic and diastolic blood pressure or in heart rate in response to induction, intubation, and incision. There was a significantly greater increase in systolic blood pressure after sternotomy in the fentanyl-O2 group. In addition, in six of seven patients receiving fentanyl-O2 there were events of sudden increase in blood pressure during various stages of surgery before the bypass, necessitating an additional fentanyl bolus or the addition of droperidol in four cases. Similar phenomena were not documented in the fentanyl-N2O/O2 group. Our studies suggest that fentanyl-O2 anaesthesia in the schedule described, in children undergoing elective cardiac surgery for Tetralogy of Fallot, A-V canal, and transposition of the great arteries, is not sufficient to prevent elevation in systolic blood pressure despite fentanyl plasma concentrations in excess of 20 ng X ml-1. The addition of nitrous oxide prevents this phenomenon.

Anesthesia, General↗
PubMed1986

Endotoxin protection against oxygen toxicity and its reversal by acetylsalicylic acid.

This study investigated the involvement of substances derived from arachidonic acid in the mechanism of endotoxin's protective action against pulmonary oxygen toxicity. Eighty-three percent of rats treated with a small dose of endotoxin (1 mg/kg) survived exposure to over 95% oxygen for 7 days. In contrast, all control rats exposed to the same oxygen concentration died within 3 days. When the endotoxin-treated rats were also treated with the soluble lysine salt of acetylsalicylic acid (100 mg/kg), 7-day survival decreased to 25%. This suggests that prostaglandin metabolism may play an important role in the protective action of endotoxin during hyperoxia.

Animals↗
PubMed1986

Cloning and expression of the pepD gene of Escherichia coli.

Peptidase D of Escherichia coli, cleaving the unusual dipeptide carnosine, was found to be encoded by the ColE1 hybrid plasmid pLC44-11. From this plasmid the pepD gene was subcloned into small vectors. As shown by successive reduction of the flanking sequences of genomic DNA, the order of genes in the region at 6 min of the E. coli K12 map is phoE, pepD, in the clockwise orientation. Insertional inactivation of the pepD gene and expression of recombinant plasmids in maxicells allowed the identification of the pepD product as a 52 kDa protein. Comparison with the 100 kDa protein molecular mass determined by gel filtration suggests that active peptidase D is probably a dimer.

Cloning, Molecular↗
PubMed1986

Unexpected alterations in fentanyl pharmacokinetics in children undergoing cardiac surgery: age related or disease related?

We assessed the pharmacokinetics of fentanyl in 19 infants and children undergoing cardiac surgery for correction of tetralogy of Fallot, A-V-canal and transposition of the great arteries. Distribution T1/2 (10.2 +/- 2.4 min) and total body clearance (13.3 +/- 6.5 ml/kg/min) were similar to adult values. An elimination t1/2 (102 +/- 85 min) shorter than in adults is readily explained by the significantly smaller distribution volume of the drug (1,203 +/- 777 ml/kg). Good correlation was found between distribution volume (Vss) and elimination t1/2 (r = 0.86, p less than 0.01) and between Vss and age of patients with tetralogy of Fallot (r = 0.85, p less than 0.01). However, older children with Fallot's had higher values of PO2 due to a milder condition (r = 0.89, p less than 0.01); consequently PO2 correlated positively with Vss (r = 0.76, p = 0.05). Fentanyl total body clearance (TBC) tends to decrease with age in these patients (r = 0.66, p = 0.05) similar to noncardiac children. Our studies suggest that the alterations in the distribution volume of fentanyl in these children may largely depend upon the severity of the hemodynamic disturbance whereas TBC of the drug may depend on their age.

Adolescent↗
PubMed1986

Complementation of class II A alleles in the immune response to (GluLysTyr) polymers.

The proliferative T cell responses to poly(GluLysTyr) (GLT) and poly(GLULysPhe) (GLPhe) are restricted by the E alpha E beta class II MHC molecule (E) in most responded strains. Some nonresponder strains that carry responder E beta, but cannot express cell surface E molecules, can complement with other nonresponder strains that provide the missing E alpha chain needed for the expression of E molecules and for responsiveness to GLT and GLPhe. Here another type of complementation is described between two E-nonexpressor haplotypes, H-2f and H-2s, which result in E-nonexpressor F1 hybrids, which are responders to GLT. The restriction element involved in this response is an Af/As hybrid molecule. The data support the hypothesis that conformational determinants resulting from the free association of alpha and beta chains in heterozygotes can increase the immune potential of the individual.

Animals↗
PubMed1986

Major histocompatibility complex-restricted and unrestricted activation of helper T cell lines by liposome-bound antigens.

Helper T lymphocytes recognize foreign antigen together with class II major histocompatibility complex (Mhc) molecules on the surface of antigen-presenting cells (APC). However, it is not known in what form soluble protein antigens are presented to T cells. The difficulty of serologically demonstrating the presence of soluble antigen on the surface of APC, the observed rapid degradation of antigen by these cells, and the finding that under special circumstances peptides of a certain protein are more antigenic that the whole molecule have led to the notion that foreign antigens must be rendered immunogenic for helper T cells by internalization, processing (probably involving enzymatic fragmentation), and redisplay on the membrane of APC in association with class II Mhc molecules. To analyze antigen recognition by helper T cells and to assess the biological significance of antigen processing, we have constructed liposomes that carry inserted class II Mhc molecules and a protein antigen coupled covalently to one of the lipid constituents of the artificial membrane. We demonstrate here that such liposomes are capable of inducing proliferative responses of long-term cultured T-cell clones, and interleukin-2 (Il-2) production by a T-cell hybridoma in an antigen-specific, Mhc-restricted fashion, in the absence of antigen-presenting cells. The responses require the presence of foreign antigen and class II molecules on the same lipid vesicles. The magnitude of responses is critically dependent on the lipid composition, the density of bound antigen, and the concentration of liposomes in cell cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Evolution of the major histocompatibility complex.

The major histocompatibility complex is a group of closely linked loci that code for molecules used by T-lymphocytes as context for the recognition of antigens. The loci fall into two classes: I, coding for molecules used as context by cytotoxic T-lymphocytes and II, used as context by helper and other regulatory T-cells. The Mhc is present in all mammals and perhaps all vertebrates. Some of the Mhc loci are highly polymorphic, while others are not. This article will summarize what is known about the genetic organization of the Mhc in different species and will discuss the selection pressures acting on the individual loci and the tempo and the mechanisms of their evolution.

Animals↗
PubMed1986

Cellular mechanisms of digoxin transport and toxic interactions in the kidney.

Renal tubular secretion of digoxin appears to be one of the main ports of elimination of the glycoside from the body. Because of its narrow therapeutic window and severe toxicity, the mechanisms of tubular handling of digoxin are important. Moreover, several drugs which are commonly administered with digoxin, including quinidine, spironolactone, verapamil and amiodarone have been shown to decrease renal clearance of digoxin without affecting GFR. We studied the handling of digoxin using in vitro and in vivo approaches. The handling of the glycoside by the brush border suggests passive reabsorption which is not enhanced by commonly coadministered drugs. Digoxin binding to the antiluminal (basal) membrane suggests that the secretion of the glycoside may not involve the pharmacologic receptor, the Na+, K+, ATPase. Using the multiple indicator dilution technique, we could directly show the two steps of secretion of digoxin: Its sequestration from the postglomerular circulation, and its appearance in the urine after transtubular transport. Digoxin transport is not inhibited by a cationic or anionic molecule (PAH and tolazoline). It is possible that digoxin is secreted by a yet unidentified transport mechanism.

Animals↗
PubMed1986

Psychotherapies with the mentally retarded.

The need for psychotherapy with the mentally retarded is evident from the high prevalence of emotional disturbance in this group. Psychotherapy can be done following the same general principles as with nonretarded persons, with modifications for the level of cognitive and language skills. Psychotherapy is effective for a broad range of problems, especially in the area of social skills. In an era of increased community placement, this area becomes an important focus for the prevention of further emotional disturbance. The paucity of research to date indicates that the various forms of psychotherapy with the mentally retarded produce favorable results. The overall outcome maximizes the contribution of the retarded to society and minimizes family pathology. Further evaluation and more systematic studies are greatly needed in order to sensitize professionals and society at large to the undeveloped potential of the retarded and their response to this form of intervention.

Humans↗
PubMed1986

Transperitoneal oxygenation with fluorocarbons.

This work investigated the improvement of arterial oxygenation in hypoxic rats during peritoneal perfusion with the oxygen-carrying perfluorocarbon blood substitute FC43. Three groups of six Wistar rats were ventilated with hypoxic gas mixtures to obtain an arterial oxygen tension (PaO2) of approximately 55 mm Hg. Two groups were subjected to peritoneal perfusion at 20 ml/min with oxygenated FC43 or the gelatine solution Haemaccel. A third group was sham operated but not perfused. In both perfused groups PaO2 increased significantly, more so in the FC43 group. Carbon dioxide tensions significantly decreased only in the FC43 group. Significant increases in arterial oxyhemoglobin saturation were seen after 15 min in the FC43 group and after 60 min in the Haemaccel group. More than 15% of oxygen consumption could be delivered by peritoneal perfusion with FC43.

Animals↗