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Biomedical subjects

R Sandin

Publications and source records attributed to R Sandin.

At least 37 records · Page 2Linked to original sources
PubMed1995

Prophylactic i.m. ephedrine in bupivacaine spinal anaesthesia.

In a double-blind, placebo-controlled, randomized study, we have investigated the efficacy of i.m. ephedrine in 98 elderly patients undergoing hip arthroplasty under spinal anaesthesia with plain bupivacaine. Fifty patients received ephedrine 0.6 mg kg-1 body weight, deep in the paravertebral muscles immediately after injection of bupivacaine, and 48 received an equal volume of saline. Patients in both groups were given the same volumes of fluid before anaesthesia. Systolic arterial pressure during the first 60 min after anaesthesia remained significantly more stable in the ephedrine-treated group, and there was also a significantly smaller number of patients in this group who had decreases in pressure of more than 30% of pre-block levels, and fewer required rescue i.v. ephedrine. An increase in heart rate or systolic pressure of > or = 20% from baseline was found in two patients in the ephedrine group and in one patient in the placebo group. We conclude that ephedrine 0.6 mg kg-1 body weight administered in the paravertebral muscles immediately after plain bupivacaine spinal anaesthesia is a simple and effective means of reducing the incidence of hypotensive episodes in the elderly patient.

Adult↗
PubMed1994

Expression of A antigens on erythrocytes of weak blood group A subgroups.

Scanning immune electron microscopy using a monoclonal anti-A antibody which reacts with all type A oligosaccharide chains revealed A antigens on less than 5% of Am and Ael cells, some of which showed extremely strong labelling. This explains why Am and Ael cells can absorb significant amounts of anti-A without being agglutinated. A3 may be a heterogeneous subgroup, since A antigens were found on 82 and 58%, respectively, of the cells of 2 A3 individuals. A antigens were found on 75% or more of Ax cells. In many weak A individuals A-positive cells are apparently best detected if an anti-A is used which reacts strongly with other A oligosaccharide chains than type 2. From hyperimmune pregnancy sera Ax, Am and Ael erythrocytes absorbed antibodies which seemed to have other fine specificities than those absorbed by A2 cells. We conclude that weak subgroups of A may deviate from A2 both by number of erythrocytes expressing A antigens and the biochemical nature of the antigens.

ABO Blood-Group System↗
PubMed1993

Activation of complement by an IgG molecule without a genetic hinge.

The hinge region links the two Fab arms to the Fc portion of the IgG molecule. It mediates flexibility to the molecule and serves as a connecting structure between the two heavy chains. In addition it provides space between the Fab and Fc parts. All three properties have been proposed to be important for the ability of IgG to initiate complement activation leading to complement-mediated cell lysis (CML). Here we report the construction of a hinge-deleted mouse-human chimaeric IgG3 molecule with specificity for the hapten NIP (3-iodo-4-hydroxy-5-nitrophenacetyl), HM-1. HM-1 lacks the genetic hinge, but has an introduced cysteine between Ala 231 (EU numbering) and Pro 232 in the lower hinge encoded by the CH2 exon. The introduced cysteine forms a disulphide bond between the two heavy chains of the molecule. In CML, HM-1 shows a greater activity than IgG3 wild type. This is the first time an IgG molecule without a genetic hinge has been found to be active in CML. We conclude that the hinge functioning as a spacer is not a prerequisite for complement activation. Rather, its major role seems to be to connect the heavy chains to each other in the amino-terminal part of CH2. Because HM-1 is expected to have low Fab-Fc flexibility, this molecular feature is probably of no importance for complement activation.

Animals↗
PubMed1993

Human IgG3 can adopt the disulfide bond pattern characteristic for IgG1 without resembling it in complement mediated cell lysis.

In this paper we describe the construction of mouse-human IgG3 mutant antibodies resembling IgG1 in their disulfide bond pattern between the heavy and light chain (H-L) and between the two heavy chains (H-H). The effector functions of these mutant antibodies were compared to normal IgG3 and IgG1. Changing only the disulfide bond pattern between the heavy and light chains did not alter the ability to induce complement mediated cell lysis (CML), regardless of the amount of corresponding antigen that had been introduced to the surface of the target cells. However, alteration of the disulfide bond pattern between the two heavy chains had a large effect on CML due to shortening of the hinge from 62 to 15 amino acids. No difference between the mutants and normal antibodies in antibody-dependent cell-mediated cytotoxicity (ADCC) was observed. This suggests that IgG3 can adopt the H-L disulfide bond pattern of IgG1 without obtaining the CML activity characteristic for IgG1.

Amino Acid Sequence↗
PubMed1993

Delayed presentation of an extradural abscess in a patient with alcohol abuse.

Three cases of extradural abscess with delayed presentation after extradural analgesia have been reported previously. The present report describes a patient with alcohol abuse who was treated for 5 days with extradural injections of bupivacaine for pain from multiple rib fractures. The first symptoms of an extradural abscess developed approximately 11 days after removal of the extradural catheter, and definite diagnosis was delayed a further 7 days.

Abscess↗
PubMed1993

Awareness during total i.v. anaesthesia.

Five cases of awareness have been identified during total i.v. anaesthesia with mechanically controlled ventilation and neuromuscular block. Two of the cases resulted from inability to deliver the target dose of anaesthetics, while the patient's need for anaesthetics was greater than anticipated in three. It is concluded that all cases were caused primarily by lack of experience, and could have been prevented. These five cases occurred in experience from approximately 2500 patients anaesthetized with this technique. Pre-, per- and postoperative data on the most recent 1727 patients have been entered into a database and may serve to provide data on the group of patients in whom the five cases of awareness occurred.

Adult↗
PubMed1993

Renal vascular response to left atrial injection. An experimental study in the pig.

It has previously been shown that a rapid, transient and pronounced reduction in superficial renal cortical blood flow can be elicited by injection of 1 ml of plasma into the left atrium of the anaesthetized pig. This renal vascular response might constitute an important error in measurements of renal blood flow by means of the microsphere technique. In the present study we have investigated total renal (ultrasonic Doppler) and superficial renal cortical (laser Doppler flowmetry) blood flow after left atrial injections of saline and autologous blood. The average reductions in total renal blood flow were 4.7 +/- 2.4% (mean +/- s.d.) and 18.4 +/- 12.5% (mean +/- s.d.) for the blood and saline injections, respectively. The flow reduction was more pronounced in the superficial renal cortex with average reductions of 17.4 +/- 26.0% (mean +/- s.d.) and 59.4 +/- 38.5% (mean +/- s.d.) for blood and saline, respectively (laser Doppler flowmetry). Furthermore, two consecutive injections of microspheres were performed. The results from the second injection were compared with those from the first injection. In the superficial renal cortex the second injection indicated a significant reduction in blood flow and an significantly increased heterogeneity in the blood flow in two different tissue volumes. No corresponding differences were found in the juxtamedullary cortex. These results indicate that the renal vascular response to a left atrial injection is detectable as a reduction in total renal blood flow and is most pronounced in the superficial renal cortex. All these results taken together constitute an important error in measurements of superficial renal cortical blood flow by the microsphere technique.

Animals↗
PubMed1993

Diclofenac for pain relief after arthroscopy: a comparison of early and delayed treatment.

The effect of diclofenac on pain after arthroscopy of the knee joint was investigated in 64 patients. The aim of this double-blind, placebo-controlled, randomised study was to compare administration before surgery with delayed treatment. The effect on postoperative pain was evaluated by means of a Visual Analogue Scale and recording of the need for additional analgesics postoperatively. After surgery, hourly assessments were performed within 6 h after the anaesthetic block (approximately 5 h after start of surgery), and on the morning after surgery. Both treatment with diclofenac before surgery and delayed treatment were superior to placebo concerning pain scores within 6 h after onset of anaesthesia (P < 0.0065 and P < 0.0005, respectively). On the morning after surgery, only delayed treatment was superior to placebo (P < 0.02). No differences in pain scores were evident between the different groups treated with diclofenac. No differences in the need for additional analgesics were found.

Arthroscopy↗
PubMed1992

Interscalene plexus block for arthroscopy of the humero-scapular joint.

Interscalene plexus block was performed in nine patients subjected to shoulder arthroscopy. The operating conditions, including muscle relaxation, were fully adequate in all patients (after additional local anaesthesia of the skin in four patients). With the exception of one patient who experienced temporary hoarseness (probably due to a concomitant block of the recurrent laryngeal nerve), no side effects were found and the patients tolerated the surgical procedure well. Interscalene block might be a suitable alternative to general anaesthesia for shoulder arthroscopy. However, additional local anaesthesia at the site where the arthroscope is to be inserted is frequently required.

Adult↗
PubMed1992

Expression of B and H antigens on red cells from a group B(weak) individual studied by serologic and scanning electron microscopic techniques.

The proposita was classified as B(el), B(y), or B(m), Le(b+) by routine blood grouping and by adsorption/elution studies using anti-A and -B hyperimmune pregnancy sera. Red cells from the proposita adsorbed as much anti-B from the hyperimmune sera as did red cells from normal B individuals, but adsorbed less anti-A,B (group O serum). Saliva contained H, but not B, soluble substance. Red cells from the proposita and a normal B donor were sensitized with monoclonal A and B blood group antibodies immunolabeled with colloidal gold particles, and examined in a scanning electron microscope. B antigens were found on more than 95 percent of normal B cells, but on only 2-3 percent of red cells from the proposita. However, when the same cells were sensitized with anti-A,B that reacted strongly with B oligosaccharides other than type 2 chains, half of the labeled red cells from the proposita were labeled more strongly than any normal B cells. Our results explain why red cells from the proposita adsorb significant amounts of anti-B and anti-A,B without being agglutinated by these antibodies. The results of both adsorption/elution and immunolabeling suggest that the B antigen on her cells differs biochemically from that on normal B cells.

Journal Article↗
PubMed1991

Chimeric mouse human IgG3 antibodies with an IgG4-like hinge region induce complement-mediated lysis more efficiently than IgG3 with normal hinge.

We have altered the amino acid sequence of the hinge and the first constant domain (CH1) of mouse/human chimeric IgG3 antibodies by site-directed mutagenesis, so as to make the sequences identical to those of IgG4. All the mutant antibodies with altered hinge region were more active in complement activation and complement-mediated lysis than native IgG3. The mutations in CH1, however, did not alter the activity. This demonstrates the importance of the hinge region in modulating this effector function. The results show that the primary structure of neither CH1 nor the hinge of IgG4 is responsible for the lack of complement activation shown by this subclass.

Amino Acid Sequence↗
PubMed1991

Variations in superficial renal cortical blood flow and tissue oxygenation: an experimental porcine model.

Renal cortical microcirculation and its relation to inulin clearance, central haemodynamics and pulmonary gas exchange were studied in eight pigs under continuous intravenous chlormethiazole-pancuronium anaesthesia. The animals were studied during six consecutive 30-min periods. Four of the animals were also studied 19 h after the first period. In the superficial renal cortex, regional blood flow (Qsrc) was measured by laser Doppler flowmetry (LDF) and tissue oxygenation (PtO2) by surface microelectrode technique. Central haemodynamics and pulmonary gas exchange values were distributed within normal ranges. The importance of stable central haemodynamics in order to perform accurate microcirculatory measurements in the renal cortex was documented. A significant relation between Qsrc and pulmonary capillary wedge pressure (PCWP) was found (P less than 0.0001) despite the fact that PCWP was distributed within a range of only 0.7 kPa (all values were well within the normal range for pigs). No other relationships were found between central haemodynamics or pulmonary gas exchange variables and renal microcirculatory parameters. Concerning renal microcirculation and inulin clearance, at least 2-3 h may be required for stabilization after surgery. The average temporal variability between measurements performed every 30 min in each animal was 6 +/- 7% (s.d.) in the LDF values and 21 +/- 21% in the PtO2 values (mean PtO2). No correlations were found between Qsrc or PtO2 and inulin clearance. Since the haemodynamic parameters, pulmonary gas exchange variables and haematocrit were distributed within narrow ranges, we regard the temporal microcirculatory variability obtained here as normal in this experimental situation, and consider the porcine model well suited for further studies concerning renal microcirculation.

Anesthesia, Intravenous↗