High frequency jet ventilation: use of the Bain system for entrainment

The use of a Bain system to convey anaesthetic gases for entrainment during high frequency jet ventilation (HFJV) was evaluated by examining the effect of varying the fresh gas flow (Vf) on the end-tidal carbon dioxide (PECO2) in 46 ASA physical status I and II patients undergoing extracorporeal shock-wave lithotripsy (ESWL). Anaesthesia was induced with methohexitone (1-2 mg.kg-1), fentanyl (1-1.5 micrograms.kg-1) and vecuronium (0.1 mg.kg-1). After endotracheal intubation with a Mallinckrodt Hi-Lo Jet cuffed endotracheal tube, the patient was immersed in a water bath and HFJV at 150 breaths per minute was instituted with an Acutronic AMS 1000 jet ventilator attached to the side channel of the Hi-Lo tube. A Bain system was attached to the proximal end of the endotracheal tube to provide gases for entrainment. Anaesthesia was maintained with an intravenous infusion of methohexitone (5 mg.kg-1.h-1) and 50% nitrous oxide in oxygen for both the jetted and entrained gases. PECO2 was determined at 5-min intervals by a single-breath technique using a calibrated Engstrom Eliza capnograph. Thirty patients were randomly allocated to receive Vf's of 50 (Group 1), 75 (Group 2) and 100 (Group 3) ml.kg-1.min-1, respectively. A further eight patients (Group 4) received a Vf of 100 ml.kg-1.min-1 for 15 min, 75 ml.kg-1.min-1 for the next 15 min and 50 ml.kg-1.min-1 thereafter. In a further group of eight patients (Group 5), Vf was initially 25 ml.kg-1.min-1 for 10 min and was then switched off for the remainder of the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of granulocyte colony stimulating factor and granulocyte-macrophage colony stimulating factor genes in human astrocytoma cell lines and in glioma specimens

Expression of granulocyte (G) and granulocyte-macrophage (GM) colony stimulating factor (CSF) genes in human cells of astroglial lineage was studied. Primers for CSFs were used to analyze RNA transcripts in 5 cultured human astrocytoma cell lines and 8 fresh brain specimens by polymerase chain reaction. Constitutive expression of mRNA transcripts of GM-CSF could be detected in all astrocytoma and one neuroblastoma cell lines, and two out of 5 unstimulated astrocytomas, U87MG and U138 MG, expressed G-CSF genes. After stimulation with interleukin (IL)-1 beta + tumor necrosis factor (TNF)-alpha, all cell lines expressed G-CSF. In addition to the cultured cells, we examined gene expression within human malignant astrocytoma, peritumoral brain and autopsied normal brains. The results show that some of the tumor and its surrounding reactive lesions express G- and GM-CSF genes but normal brains do not. The concentration of G- and GM-CSF in supernatants of cultured cells was assessed at the protein level by ELISA. A low level of GM-CSF activity was constitutively present in all astrocytomas. G-CSF was detected in unstimulated U87MG and U138MG and other cell lines could synthesize G-CSF after the stimulation of IL-1 beta and TNF-alpha at the level of mRNA. Furthermore, the concentration of CSFs increased markedly upon stimulation with IL-1 beta and/or TNF-alpha in both a time- and dose-dependent fashion. From these results, it is suspected that astroglial cell-derived CSFs may participate in local immune reactions accompanying infection, degeneration and malignancies in the brain.

Chemical synthesis of 10 kDa chaperonin. Biological activity suggests chaperonins do not require other molecular chaperones

Molecular chaperones are required for the correct folding and assembly of certain other polypeptides. It is not known whether molecular chaperones themselves require other chaperones to become functional. A 97-amino acid chaperone, the chaperonin 10 protein was chemically synthesised so that during synthesis and purification there was no contact of the chaperone with any other protein. The purified, synthetic chaperonin 10 protein formed oligomeric structures spontaneously and was biologically active as a chaperonin. This is the first description of a chemically synthesised chaperonin, and suggests that no other chaperones are required for correct folding, polymerisation and biological activity of this chaperone.

HPV DNA typing of adult-onset respiratory papillomatosis

Respiratory papillomatosis is a recalcitrant, human papillomavirus-induced disorder of the upper airways. Using in situ hybridization and biotinylated deoxyribonucleic acid (DNA) probes, the type of human papillomavirus (HPV) in nine adults was determined both at presentation and during subsequent recurrences. Fifty-three biopsies obtained from seven men and two women over a 10-year period were examined for HPV 6, 11, 16 and 18. All patients had either type 6 or 11. One dual infection was found. Despite intensive therapy with lasers with or without alpha interferon, no elimination or change in viral type occurred. Despite identical histologies, the amount of HPV DNA present in a given patient's papillomata varied markedly. The results suggest that adult-onset respiratory papillomatosis is due to HPV 6 and/or HPV 11, and that its recurrent nature, despite therapy, is due to persistence of a viral reservoir.

Atropine-induced heart rate changes: a comparison between midazolam-fentanyl-propofol-N2O and midazolam-fentanyl-thiopentone-enflurane-N2O anaesthesia

Atropine-induced heart rate (HR) changes were studied in 19 patients (ASA physical status I) during anaesthesia-maintained predominantly with propofol-N2O or thiopentone-enflurane-N2O. Ten patients (Group A) received midazolam (0.07 mg.kg-1), fentanyl (1 microgram.kg-1), propofol (2 mg.kg-1) and succinylcholine (1 mg.kg-1). Following tracheal intubation, anaesthesia was maintained with propofol (6 mg.kg-1.hr-1), N2O (67 per cent) and O2 (33 per cent). In nine patients (Group B) thiopentone (4 mg.kg-1) was substituted for propofol and anaesthesia maintained with N2O (67 per cent) O2 (33 per cent), and enflurane (0.5 per cent inspired concentration). The study was non-randomised because Group B patients were only included if HR before administration of atropine less than 90 beats.min-1. IPPV was performed in all patients using a Manley ventilator (minute vol. 85 ml.kg-1; tidal vol. 7 ml.kg-1). Ten minutes after tracheal intubation, incremental doses of atropine (equivalent cumulative doses: 1.8, 3.6, 7.2, 14.4, 28.8 micrograms.kg-1) were administered at two-minute intervals and HR responses calculated during the last 45 sec of each intervening period. No differences were observed between the groups following 1.8 and 3.6 micrograms.kg-1 atropine, but propofol-N2O anaesthesia was associated with reduced responses (P less than 0.01) following 7.2, 14.4 and 28.8 micrograms.kg-1 atropine. These results suggest that there is a predominance of parasympathetic influences during propofol-N2O anaesthesia compared with thiopentone-enflurane-N2O anaesthesia.

Ascorbic acid potentiates the inhibitory effect of dopamine on prolactin release: a putative supplementary agent for PIF

Dopamine has a catechol group which can be easily oxidized by mild oxidizing agents. Ascorbic acid has been routinely added to a dopamine solution in order to protect it from oxidation. We have examined the effect of ascorbic acid on dopaminergic inhibition of prolactin release. Male rat pituitary cells were dispersed using trypsin and cultured for 5-7 days before experiments. Ascorbic acid did not stimulate nor inhibit prolactin release in both static monolayer culture and dynamic perifusion systems, but potentiated by approximately 100 times the inhibitory effect of dopamine on prolactin release. In order to differentiate chemical protection from potentiation, we tested the potentiation effect of isoascorbic acid which is an epimer of biologically active L-ascorbic acid but is biologically less active. Our results indicated that isoascorbic acid caused less potentiation of the dopaminergic effect on prolactin release than did ascorbic acid. In a perifusion system, a high concentration of dopamine (100 nmol/l) was unable to inhibit prolactin release for a 1 h experimental period, but a low concentration of dopamine (10 nmol/l) plus ascorbic acid (10 mumol/l) inhibited prolactin release for the entire 1 h perifusion period. There is a strong possibility that ascorbic acid may be a physiological supplementary agent for the prolactin-release inhibiting factor (PIF) since the blood concentration of ascorbic acid is rather high (23-85 mumol/l).

Multiple T and B cell epitopes in the S1 subunit ("A"-monomer) of the pertussis toxin molecule

The immunogenicity and reactogenicity of Bordetella pertussis vaccine are mediated in part by the S1 subunit of pertussis toxin (PT). To identify the immune epitopes in the S1 subunit of PT, synthetic peptides were prepared and tested for their capacity to induce antibodies in mice with different MHC genotypes. In BALB/c mice, peptides corresponding to sequences 1-17, 70-82 and 189-199 generate T cell proliferative responses, induce the production of antibodies capable of neutralization of the toxin in the Chinese hamster ovary-cell assay, and protect mice from a shock-like syndrome caused by alternate injections of BSA and PT. Protection and neutralization correlated with the ability of these peptides to elicit high anti-PT titers. Different B cell epitopes were detected in other inbred mouse strains. The antibody reactivity against synthetic peptides from two infants vaccinated with pertussis vaccine was tested. These infants had antibodies reactive to a variety of epitopes in the S1 subunit, including peptides 1-17, 70-82, 99-112, 135-145, and 189-199. Thus, it appears that there are multiple T and B cell epitopes in the S1 subunit of PT.

Multiple T and B cell epitopes in the S1 subunit ("A"-monomer) of the pertussis toxin molecule

The immunogenicity and reactogenicity of Bordetella pertussis vaccine are mediated in part by the S1 subunit of pertussis toxin (PT). To identify the immune epitopes in the S1 subunit of PT, synthetic peptides were prepared and tested for their capacity to induce antibodies in mice with different MHC genotypes. In BALB/c mice, peptides corresponding to sequences 1-17, 70-82 and 189-199 generate T cell proliferative responses, induce the production of antibodies capable of neutralization of the toxin in the Chinese hamster ovary-cell assay, and protect mice from a shock-like syndrome caused by alternate injections of BSA and PT. Protection and neutralization correlated with the ability of these peptides to elicit high anti-PT titers. Different B cell epitopes were detected in other inbred mouse strains. The antibody reactivity against synthetic peptides from two infants vaccinated with pertussis vaccine was tested. These infants had antibodies reactive to a variety of epitopes in the S1 subunit, including peptides 1-17, 70-82, 99-112, 135-145, and 189-199. Thus, it appears that there are multiple T and B cell epitopes in the S1 subunit of PT.

Triiodothyronine regulates insulin-like growth factor-I binding to cultured rat pituitary cells

Abstract Triiodothyronine (T(3)) stimulates the synthesis of growth hormone and enhances the growth of neoplastic rat pituitary somatomam-motrophs (GH cells) in culture. Moreover, T(3) has been shown to stimulate the production and secretion of an autocrine growth factor by these cells. We have previously demonstrated the presence of specific receptors for insulin-like growth factors (IGF) on GH cells. Since GH(3) cells contain mRNA encoding IGF-I, it has been suggested that IGF-I might act in an autocrine fashion in these cells. Therefore, it was of interest to learn how T(3) affects IGF-I binding to GH(3) cells. T(3) increased [(125)I]IGF-I binding in a time - and dose-dependent manner. After 48 h of exposure to T(3), an increase in IGF-I binding was seen with 10(-11)M T(3), maximizing with 10(-8)M T(3). When cells were exposed to 10(-8) T(3), [(125)I]IGF-I binding reached a maximum of 218 +/- 20.8% of control (+/-SEM, P < 0.002) after 72 h of incubation. Scatchard analysis indicated that T(3) did not alter the K(d) of IGF-I for its receptor, but that the total receptor number was increased. Dexamethasone (10(-7)M) inhibited the T(3)-induced increase in IGF-I binding, but glucocorticoid alone did not substantially alter receptor number. No significant change in insulin or IGF-II binding was seen after hormone treatment. 10(-8) M T(3) or IGF-I increased the growth of the GH(3) cells by >/=30%. Our data indicate that T(3) upregulates IGF-I binding in GH(3) cells without altering insulin binding and thereby provides a means for enhancing potential autocrine regulation in this cell line.

Effect of vecuronium on atropine-induced changes in heart rate

The effect of vecuronium on the heart rate response to atropine has been studied by comparing dose-response relationships in two groups of patients who underwent extracorporeal shock wave lithotripsy. One group received vecuronium (0.1 mg/kg) and the other acted as control. Incremental doses of atropine (1.8, 1.8, 3.6, 7.2 and 14.4 micrograms/kg) were administered and changes in heart rate recorded. No significant differences were observed between the two groups following each incremental dose of atropine.

Prevention of postdural puncture headache after spinal anaesthesia for extracorporeal shockwave lithotripsy. An assessment of prophylactic epidural blood patching

The prevention of postdural puncture headache after spinal anaesthesia for extracorporeal shockwave lithotripsy was investigated by a controlled clinical trial which compared epidural injection of 10 ml of autologous blood with 10 ml of normal saline immediately after intrathecal injection of local anaesthetic. The incidence of postdural puncture headache was 8.3% in the group that received blood compared with 45% in the group that received saline, a significant reduction (p less than 0.01). The incidences of backache and lower limb paraesthesiae were similar in both groups. No serious complications were reported.

Treatment of the chest wall

Irradiation of the chest wall is sometimes given following radical or modified radical mastectomy. The aim of treatment planning in such cases is to deliver a uniform dose to a superficial layer of tissue a few centimeters thick with an acceptably low dose to underlying tissues, particularly the lung. Both tangential photon beams and appositional electron beams have been used for this purpose, the choice between them being determined by the radiation modalities available, the extent and thickness of the designated target volume and the curvature of the patient's contour in the region. In this paper we will consider a few examples of both types of treatment with emphasis on the use of multiple electron fields. Dose distributions for the following plans were calculated using the system developed at the Cross Cancer Institute in Edmonton. In this system electron dose calculations are based on the Fermi-Eyges theory of multiple Coulomb scattering using the programs developed by Hogstrom and his co-workers.

MHC-restricted recognition of immunogenic T cell epitopes of pertussis toxin reveals determinants in man distinct from the ADP-ribosylase active site

The S1 subunit of Pertussis toxin (PT) is responsible for the reactogenicity and in part the immunogenicity of Bordetella pertussis vaccine. The critical residues associated with the immunomodulatory effects of PT were located around Glu140 in the S1 subunit. In man, T cell responses to PT are directed at S1 peptides distinct from Glu140. Two such epitopes, p64-75 and p151-161, are immunogenic in a panel of individuals covering a wide range of HLA genotypes. The response to PT peptides is HLA class II restricted. The response to p64-75 is blocked by an anti-HLA-DQ mAb, while that to p151-161 is blocked by an anti-HLA-DR mAb. These findings may allow for the development of a B. pertussis vaccine free from reactogenicity.

CT treatment planning of the liver

The article deals with CT treatment planning of the liver to maximize the dose to the liver but minimize the dose to the right kidney, spinal cord, and bowels. (The left kidney is out of the field due to the oblique angles of the fields.) This is achieved by right kidney shielding reconstruction from multislice CT treatment planning and by the oblique angles of the fields. Without CT, it is not possible to utilize oblique fields to cover the liver. With conventional AP-PA fields, not only is the whole liver treated but also most of the right kidney, half of the left kidney, bowels and spinal cord. Tolerance dose to the kidneys is exceeded if adequate dose is delivered to the liver. Some new computer algorithms display a bird's eye view of the shielding but this paper presents for the first time, a technique for actual shielding reconstruction from multislice CT treatment planning for use by the radiation oncologist when shielding blocks are drawn on the simulator films.

Characterization of a major encephalitogenic T cell epitope in SJL/J mice with synthetic oligopeptides of myelin basic protein

The C-terminal 89-169 amino acid fragment of myelin basic protein (MBP) causes experimental allergic encephalomyelitis (EAE) in SJL/J mice. In order to identify the encephalitogenic T cell epitope, we have examined the fine specificity of encephalitogenic SJL/J T cell clones with synthetic peptides derived from the C-terminal 89-169 amino acids of MBP. These peptides were examined for their immunogenic and encephalitogenic activity in the SJL/J mouse. The SJL/J-derived, encephalitogenic T cell clone, 4b.14a, was shown to be responsive to rat myelin basic protein synthetic peptides pR89-101 (VHFFKNIVTPRTP) as well as to intact MBP. Its response was effectively blocked by mAb 10-2.16 (anti-I-As) as was the response to intact MBP. Furthermore, pR89-101 was revealed to be highly immunogenic for the (PLSJ)F1 mouse in terms of lymphocyte proliferation, but not for the PL/J mouse, in spite of the fact that there exists a strong bias to H-2u restricted responses in the (PLSJ)F1 mouse at the T cell level. By using pR89-101, T cells of (PLSJ)F1 origin were revealed to recognize the peptide in association with the I-As molecule on (PLSJ)F1 antigen presenting cells (APC). When examined for encephalitogenicity for the SJL/J mouse, pR89-101 was found to be as encephalitogenic as intact rat MBP. These results demonstrated that MBP peptide pR89-101 is a major encephalitogenic determinant for the SJL/J mouse.

ADP-ribosyltransferase activity of pertussis toxin and immunomodulation by Bordetella pertussis

Pertussis toxin is produced by the causative agent of whooping cough, Bordetella pertussis, and is an adenosine diphosphate (ADP)-ribosyltransferase capable of covalently modifying and thereby inactivating many eukaryotic G proteins involved in cellular metabolism. The toxin is a principal determinant of virulence in whooping cough and is a primary candidate for an acellular pertussis vaccine, yet it is unclear whether the ADP-ribosyltransferase activity is required for both pathogenic and immunoprotective activities. A B. pertussis strain that produced an assembled pertussis holotoxin with only 1 percent of the ADP-ribosyltransferase activity of the native toxin was constructed and was found to be deficient in pathogenic activities associated with B. pertussis including induction of leukocytosis, potentiation of anaphylaxis, and stimulation of histamine sensitivity. Moreover, this mutant strain failed to function as an adjuvant and was less effective in protecting mice from intracerebral challenge infection. These data suggest that the ADP-ribosyltransferase activity is necessary for both pathogenicity and optimum immunoprotection. These findings bear directly on the design of a nontoxic pertussis vaccine.

Comparative evaluation of general, epidural and spinal anaesthesia for extracorporeal shockwave lithotripsy

The results of a prospective randomised evaluation of general anaesthesia (GA), epidural anaesthesia (EA) and spinal anaesthesia (SA) for extracorporeal shockwave lithotripsy are presented. GA provided speed and reliability but resulted in a high incidence of postoperative nausea, vomiting and sore throat. Both regional techniques conferred the advantages of an awake, cooperative patient, but EA required a longer preparation time than SA and more supplementary treatment with fentanyl or midazolam. A major drawback associated with the use of SA was a 42% incidence of postspinal headache. All three techniques were associated with hypotension on placement in the hoisl; bath immersion resulted in significant rises in blood pressure in the EA and SA groups and a more variable (overall non-significant) response in the GA group.

Idiopathic hypereosinophilic syndrome with polymyositis

We have reported a case of idiopathic hypereosinophilic syndrome (HES) with polymyositis, in which there was marked eosinophilic leukocytic infiltration of the myocardium and striated skeletal muscles, particularly of the diaphragm, with foci of necrosis and areas of fibrosis. We believe this to be the first detailed report of the involvement of the diaphragm in HES.

Anaesthesia for extracorporeal shock-wave lithotripsy. A comparison of propofol and methohexitone infusions during high frequency jet ventilation

A continuous infusion of propofol 2.0-2.5 mg/kg for induction followed by 9 mg/kg/hour for the first 30 minutes and 6 mg/kg/hour thereafter, was compared with methohexitone 1.5 mg/kg for induction followed by 4.8 mg/kg/hour thereafter for maintenance of anaesthesia in a randomised study of 40 patients who underwent extracorporeal shock-wave lithotripsy using high frequency jet ventilation (HFJV). Systolic blood pressure was significantly lower in the propofol group after induction of anaesthesia, tracheal intubation, placement in the semirecumbent position in the hoist, bath immersion and after 5, 10 and 30 minutes of treatment. Diastolic blood pressure was significantly lower in the propofol group after intubation, placement in the hoist, bath immersion and after 5, 10 and 15 minutes of treatment. Heart rate was significantly lower in the propofol group after induction, intubation, placement in the hoist and bath immersion. There was no significant difference in the quality of induction between the two groups. Quality of maintenance of anaesthesia was judged to be poor in six out of 20 patients who received methohexitone compared with one out of 20 who received propofol but this difference did not reach statistical significance. There was no significant difference between the recovery times for the two groups but six out of 20 patients who received methohexitone were judged to have a poor recovery from anaesthesia compared with none in the propofol group (p less than 0.05). Propofol was associated with excellent induction, maintenance and recovery characteristics but it had a propensity to produce greater decreases in blood pressure, which were most marked when the patient was placed in the semirecumbent position in the hoist.

Cardiovascular effects and placental passage of dantrolene in the maternal-fetal sheep model

Using the chronic maternal-fetal sheep preparation, nine pregnant ewes were studied to determine the effects of intravenous dantrolene sodium on maternal and fetal physiology, with particular reference to its placental passage, and its effects on uterine blood flow and uterine tone. Two doses of dantrolene sodium were studied: 1.2 mg/kg and 2.4 mg/kg. After 2.4 mg/kg, maternal cardiac output increased 29% (P less than 0.05) after 1 min and returned to normal after 30 min. Maternal mean arterial pressure increased 13% after 1 min and remained significantly elevated (P less than 0.01) for 3 h. No significant changes (P greater than 0.05) were observed in maternal heart rate, uterine artery blood flow, or central venous pressure. Maternal arterial pH declined from 7.42 to 7.39 (P less than 0.01) after 1 min and returned to baseline values after 10 min. Fetal heart rate decreased 24% (P less than 0.01) after 3 min and returned to normal after 10 min; the mean fetal arterial pressure remained unchanged (P greater than 0.05). Fetal arterial pH declined from 7.29 to 7.27 (P less than 0.05) after 1 min and remained significantly decreased for 120 min. Similar changes of lesser magnitude and shorter duration were seen following the 1.2 mg/kg dose. Maternal levels of dantrolene were less than 3 micrograms/ml. Although an equilibrium between maternal and fetal plasma dantrolene concentrations was apparent at 5 min, the fetal levels of dantrolene were approximately 10% of the mother's. The results indicate that the administration of intravenous dantrolene at 1.2 mg/kg or 2.4 mg/kg has no clinically significant adverse effect on mother or fetus in the sheep model.

Effect of chronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on sister chromatid exchange levels in peripheral lymphocytes of the rhesus monkey

Frequencies of sister chromatid exchanges and chromosomal aberrations were examined in peripheral lymphocytes of Rhesus monkeys which had been fed a diet containing 25 parts per trillion 2,3,7,8-tetrachlorodibenzo-p-dioxin for a period of 4 years. When compared to non-exposed control animals, no significant differences were noted for either of these cytogenetic endpoints. In addition, there was not a significant difference in sister chromatid exchange response to a challenge dose of mitomycin C in cells from 2,3,7,8-tetrachlorodibenzo-p-dioxin exposed animals compared to controls. Our results confirm the lack of genotoxic effects associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure.

Treatment of lethal pertussis vaccine reaction with histamine H1 antagonists

We studied mortality after pertussis immunization in the mouse. Without treatment, 73 of 92 animals (80%) died after injection of bovine serum albumin (BSA) on day +7 of pertussis immunization. After pretreatment with 3 mg of cyproheptadine, 2 mg mianserin, or 2 mg chlorpheniramine, only 5 of 105 animals (5%) died after receiving BSA on day +7 (p less than 0.001). Blockade of histamine H1 receptors may reduce mortality in pertussis immunization-induced encephalopathy in mice.

Beta-adrenoceptor blockade and suxamethonium-induced rise in plasma potassium

The effects of beta-adrenergic blockade on the suxamethonium-induced rise in arterial plasma potassium were studied in patients who presented for open heart surgery. No potentiation of the immediate rise in plasma potassium was observed.

Induction of sister chromatid exchanges by inhibitors of topoisomerases

To investigate the role of topoisomerases in the production of sister chromatid exchanges, the effects of inhibitors of type I and II topoisomerases on baseline and mutagen-induced sister chromatid exchanges were compared. V79 cells were treated with VM-26 and m-AMSA, known inhibitors of type II topoisomerase, or with camptothecin, the only known inhibitor of type I topoisomerase. We observed that inhibitors of both type I and II topoisomerases induced high levels of sister chromatid exchanges at 10(-6) M, and that the dose-response curves of these drugs were very similar. A clear heterogeneity in the distribution patterns of exchanges induced by inhibitors of topoisomerases was observed. We believe that this heterogeneity in response to these compounds is due to variation in sensitivity within the cell cycle. We also studied interactions of these agents with mitomycin-C and with PUVA (8-methoxypsoralen + UVA), both cross-linking agents and potent sister chromatid exchange inducers, and with x-rays, an agent that induces high levels of DNA strand breaks. No significant change in exchange levels was observed in interactions between topoisomerase inhibition and the levels induced by the agents studied. We conclude that double-strand break prevalence, known to be increased through inhibition of type II topoisomerase, is not the primary mechanism for induction of sister chromatid exchanges. We further conclude that acute inhibition of type I and type II topoisomerases does not influence substantially the induction of exchanges by other agents.

Pertussis toxin is required for pertussis vaccine encephalopathy

A mouse model for encephalopathy induced by pertussis immunization has been described; it has features that closely resemble some of the severe reactions, including seizures and a shock-like state leading to death, occasionally seen after administration of Bordetella pertussis (whooping cough) vaccine. Susceptibility to encephalopathy maps to genes of the major histocompatibility complex and correlates as well with the genetic regulation of the level of antibody response to bovine serum albumin. In this study we have investigated which bacterial determinant is responsible for the encephalopathy. Two lines of evidence implicate pertussis toxin as the active bacterial component. Single-site mutants of B. pertussis with single affected virulence factors were tested. A mutant that produces a defective pertussis toxin had greatly diminished capacity to induce encephalopathy, whereas a hemolysin- and adenylate-cyclase-deficient avirulent mutant had the same activity in the mouse model as a virulent strain. Purified pertussis toxin plus bovine serum albumin was tested and found to induce the lethal encephalopathy, demonstrating that the toxin was the critical constituent of B. pertussis responsible for encephalopathy.

Reversal of experimental allergic encephalomyelitis with monoclonal antibody to a T-cell subset marker

Administration of a monoclonal antibody (GK1.5) that recognizes the L3T4 marker present on helper T cells prevented the development of experimental allergic encephalomyelitis (EAE) in mice. Furthermore, treatment with GK1.5 reversed EAE when the antibody was given to paralyzed animals. In vivo injection of GK1.5 selectively reduced the number of L3T4+ cells in the spleen and the lymph nodes. These results suggest that manipulation of the human equivalent of the murine L3T4+ T-cell subset with monoclonal antibodies may provide effective therapy for certain autoimmune diseases.

Arterial plasma potassium measured continuously during exercise in man

Five continuous records of arterial plasma potassium were obtained from three normal subjects during brief periods (5-7 min) of exercise (100 W). In two of these subjects hepatic venous blood samples were withdrawn at 0.5-1.0 min intervals and analysed in vitro for plasma potassium. Arterial plasma potassium rose rapidly at the start of exercise from 3.8 +/- 0.3 mmol/l (mean +/- SD) to plateau levels of 5.4 +/- 0.1 mmol/l. One of the above subjects and a further subject were studied after beta-blockade with propranolol. This resulted in an exaggerated rise in arterial plasma potassium during exercise. Hepatic venous potassium measurements indicated that the liver probably had little effect on potassium changes during exercise. The changes in arterial plasma potassium during exercise are rapid and substantial. If transmitted to the extracellular fluid these changes would alter cell transmembrane potential and might as a result alter receptor sensitivity.

Molybdenum(VI) complexes of Schiff bases derived from salicylaldehyde and 2-aminoethanethiol (cysteamine)

The reaction of salicylaldehyde and 2-aminoethanethiol (cysteamine) in methanol results in two distinct products: a yellow oil, 2-(2-mercaptoethyliminomethyl)phenol, and a yellow crystalline solid, 2,2'-[dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenol, which is an oxidation product of the former. The latter compound may also be prepared from salicylaldehyde and 2,2'-dithio-bis(ethylamine) (cystamine) in methanol. 2-(2''-Mercaptoethyliminomethyl)phenol reacts with MoO2(acac)2 (acac = pentane-2,4-dionate) in methanol to yield a red crystalline solid with empirical formula MoO2(mep) [mep = 2-(2"- mercaptoethyliminomethyl)phenolate]. This red solid exists as a dimer in the solid state. It forms adducts with dimethyl sulfoxide, hexamethylphosphoric acid triamide and pyridine. 2,2'-[Dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenol reacts with MoO2(acac)2 to yield a pale yellow solid. It is a monomeric compound whose formula is MoO2(dbp) {dbp = 2,2'- [dithiobis(ethane-1,2-diyl)bis(nitrilomethylidyne)]bisphenolate}. It does not form an adduct and is decomposed by an excess of tetramethylammonium hydroxide in methanol.

Prevention of experimental allergic encephalitis with in vivo administration of anti I-A antibody. Decreased accumulation of radiolabelled lymph node cells in the central nervous system

Experimental allergic encephalitis (EAE) can be prevented with the in vivo administration of monoclonal anti I-A antibody. A radiometric assay was developed to measure the accumulation of lymphocytes in the central nervous system of EAE animals. A direct correlation was observed between severity of clinical disease and the amount of radiolabelled lymph node cells (LNC) in the central nervous system. Injection of anti I-A antibody in vivo prevented clinical EAE and decreased the accumulation of radiolabelled LNC in spinal cord after immunization with mouse spinal cord homogenate and adjuvants.

Cobalt(II), nickel(II) and zinc(II) complexes of 3,3'-[Ethane-1,2-diylbis(imino)]-bis(propanamide) in solution

The interactions of 3,3'-[ethane-1,2-diylbis(imino)]bis(propanamide) (H2eip) with cobalt(II), nickel(II) and zinc(II) ions in 0.1 mol 1-1 KNO3 at 25�C have been studied by means of potentiometry. In addition, the nickel system has also been studied by means of spectrophotometry, infrared and 13C n.m.r. spectroscopy. Equilibria (1) and (2) were found to hold: Ni2++H2eip↔Ni(H2eip)2+ (1) Ni2++H2eip↔Ni(H2eip)2H+ For the other metal ions only equilibrium (1) was observed experimentally. The values of the equilibrium constants for cobalt, nickel and zinc are log K1 5.39, 7.59 and 5.05 respectively, and pK1'' 19.24 for nickel. For Ni(H2eip)2+, three absorption maxima were found at γmax 746, 595 and 367 nm with εmax values 6.5, 6.9 and 11.5 cm-1 mol-1l. respectively; for Ni(eip), only one absorption maximum at γmax 446 nm with εmax 91.9 cm-1 mol-1 l. was observed.

Early changes in plasma potassium after acute alterations in PaCO2 in anesthetized dogs, monitored continuously with intravascular potassium-selective electrodes

Changes in plasma potassium in the first 10 min after alterations in PaCO2 in anesthetized greyhounds were monitored continuously in vivo with potassium-selective electrode catheters. Elevation of PaCO2 resulted in a small transient fall in plasma potassium whereas reduction in PaCO2 resulted in a small transient rise in plasma potassium. Maximum changes occurred at approximately 5 min after alterations in PaCO2 with levels tending to return to control thereafter. Changes of similar magnitude in normal man would not be expected to have an adverse effect on cardiac function, but they may have greater significance in subjects with pre-existing abnormal potassium levels, during concurrent treatment with digoxin, and after sudden alterations in PaCO2 in chronic hypo- or hypercapnic conditions.

Continuous intravascular monitoring of epinephrine-induced changes in plasma potassium

Ion-selective electrode catheters were used for continuous monitoring of epinephrine-induced changes in plasma potassium in different parts of the circulation of anesthetized greyhounds. Bolus injections and continuous infusions of epinephrine produced dose-related changes consisting of an initial transient increase followed by a decrease to levels below control. The latter part of the response was relatively short-lived in the case of bolus injections, but when the epinephrine was administered by continuous infusion, a progressive fall was maintained for the duration of the infusion. During the period when potassium levels were undergoing an acute change, marked differences were seen between concentrations in different parts of the circulation. Further studies are needed to delineate the incidence and extent of similar changes in humans, and their significance in producing dangerous dysrhythmias.

Continuous intravascular monitoring of plasma potassium using potassium-selective electrode catheters

A fast-responding, potassium-selective electrode catheter suitable for continuous intravascular monitoring is described. Traces illustrating its performance in human patients and anesthetized greyhounds are shown. There was no significant difference between off-line blood samples analysis (using an in vitro electrode) and results obtained with the in vivo electrode; mean absolute difference was 0.11 +/- 0.11 (SD) mM. The technique described is simple and reliable, and represents an advance on existing intermittent sampling methods for detailed monitoring of rapid changes in plasma potassium.

Copper(II) complexes of 3,3'-[Ethane-1,2-diylbis(imino)]bis(propanamide) in solution

The interaction of copper(II) ions with 3,3'-[ethane-1,2-diylbis(imino)]bis(propanamide) (H2eip) in 0.1 mol l-l KNO3 at 25�C has been studied by means of spectrophotometry and potentiometry. The acid dissociation constants of the ligand have also been determined under the same conditions. Equilibria (1) and (2) apply to the free ligand: (H2eip)H22+KA↔(H2eip)H++H+(1) (H2eip)H22+KA↔(H2eip)H+ (2) For the copper complexes, equilibria (3)-(5) were found to hold: Cu2+H2eip↔Cu(H2eip)2+ (3) Cu(H2eip)2+↔Cu(H2eip)++H+ (4) Cu(Heip)+↔Cu(eip)+H+ (5) The values of the equilibrium constants are: pKA 5.79, pKB 8.88, log K 11.89, pK'1 8.06, pK'2 9.48. The absorption maxima and the extinction coefficients of Cu(H2eip2+ and Cu(eip) are, respectively, γmax654 nm, εmax138 cm-1 mol-1 1 and γmax 543 nm, εmax 98.6 cm-1 mol-1 l.