The detection of changes in psychological state using a novel pharmacological conditioning procedure

Using a novel pharmacological conditioning procedure, pigs were conditioned to discriminate the effects of a subconvulsant dose of the anxiogenic drug pentylenetetrazole (PTZ; 2.8-10 mg/kg, i.v.) from saline. The operant chamber provided two levers at which pigs were trained to press at a fixed ratio of 20 presses per food reward (FR 20). The animals were conditioned to select both levers alternately following saline treatment and to select one lever only following PTZ treatment. This procedure enabled the onset and offset of the PTZ stimulus to be detected within single test sessions; infusion of PTZ to animals already selecting both levers alternately after a saline pretreatment induced a period of response exclusive to the PTZ lever followed by a return to an alternation of lever selection response. The ability of the novel procedure to detect the time course of the drug cue should improve future evaluations of the psychological states induced by centrally acting drugs. With PTZ as the training drug, the novel procedure presents a valuable means to study the neurobiology of anxiety.

Outer membrane protein patterns mark clones of Escherichia coli O2 and O78 strains that cause avian septicemia

Major outer membrane proteins were isolated from 36 Escherichia coli strains representing six common clones of the O2 and O78 serogroups implicated in avian colisepticemia. Clonal relationships among isolates were inferred from an analysis of polymorphism at 20 enzyme-encoding loci detected by multilocus enzyme electrophoresis. For isolates of these clones, there was a high concordance (greater than 90%) between identity in multilocus genotype and major outer membrane protein patterns. The results indicate that major outer membrane protein patterns discriminate among the genetically different clonal groups that constitute the heterogeneous O2 and O78 serogroups associated with avian disease.

Combined effect of infection and heavy wrapping on the risk of sudden unexpected infant death

Three methods were used to investigate the role of infection in sudden unexpected infant death (SUD): (i) microbiological comparison of SUD victims and matched, live, community controls; (ii) postmortem classification of the contribution of infection to death; and (iii) case-control analysis of the relative risk associated with both infection and heavy wrapping. Limited sampling from the upper respiratory tract and gut in SUD victims and controls showed no significant excess of viral infection in the SUD victims (odds ratio = 1.98, 95% confidence interval (CI) 0.9 to 4.5). At postmortem examination, infection explained death in 3/95 babies and may have contributed to death in 37/95. Over 70 days of age, the combined presence of viral infection and wrapping in excess of 10 togs produced an odds ratio of SUD of 51.5 (95% CI 5.64 to 471.48) compared with wrapping of less than 6 togs. Viral infection was not a major risk factor as long as babies were lightly wrapped. In heavily wrapped babies the presence of a viral infection greatly increased the risk of SUD.

Wearing a wife-assault-prevention button: impact on a family practice

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Isolation of Staphylococcus aureus from sites other than the lactating mammary gland

The body sites of 163 heifers, bedding and feedstuff samples, flies, and hands and nares of the research personnel were sampled in order to determine the sources of Staphylococcus aureus in a dairy herd other than the lactating mammary gland. Lesions on the udder of lactating animals and the air in the milking parlor were also sampled. Staphylococci isolated from bedding samples were identified as to species. Staphylococcus aureus was isolated from all sources examined except flies. An enrichment procedure was necessary for isolating S. aureus from two bedding samples although other Staphylococcus species were present in high numbers. The designation "environmental staphylococci" is proposed for Staphylococcus species that were apparently free-living in the environment.

Incidence of penicillin tolerance among blood culture isolates of Streptococcus sanguis, 1987-88

Laboratories that reported isolations of Streptococcus sanguis from blood cultures to the Communicable Disease Surveillance Centre (CDSC) Colindale were requested to submit strains to Bath Public Health Laboratory to allow the prevalence of penicillin tolerance within different biotypes of this species to be studied. One hundred and fifty one Streptococcus spp were received from 78 United Kingdom laboratories in one year. Strains were identified using the API 20 Strep, and minimum inhibitory concentrations (MICs) of penicillin were determined using the spiral gradient plate method. Penicillin tolerance was detected by spraying beta-lactamase over inoculated gradient plates, reincubating for 48 hours and counting the number of surviving organisms represented by colonies. There were 57 different API identification profiles encountered in the survey. Most S sanguis I/1 strains were penicillin tolerant, most S sanguis II strains were non-tolerant. The overall geometric mean MIC of penicillin was considerably lower for S sanguis I/1 than for all other biotypes. The distribution of biotypes and the geometric mean MIC of penicillin for each biotype were not significantly different for infective endocarditis strains than for all strains tested, suggesting little or no association between penicillin tolerance and the seeding of endocardium. When the reactions obtained using API 20 Strep were compared with a recent taxonomic study of viridans streptococci, 22 of 38 S sanguis I/1 strains could be reclassified as S gordonii; all these strains were penicillin tolerant. Such reclassification would allow likely penicillin tolerant strains to be predicted.

Differentiation of Acanthamoeba strains from infected corneas and the environment by using restriction endonuclease digestion of whole-cell DNA

Restriction endonuclease digestion of Acanthamoeba whole-cell DNA was used to study the relationship between 33 morphologically identical strains from keratitis cases (30 strains), contact lens storage containers (2 strains), and soil (1 strain). Samples digested with BglII, EcoRI, or HindIII and separated by agarose gel electrophoresis contained detectable mitochondrial DNA restriction fragment length polymorphisms (RFLPs). By comparing RFLPs, the strains could be assigned to seven multiple-strain and three single-strain groups. The largest of these contained nine strains, eight of which were isolated in keratitis cases in various locations worldwide and may indicate a group particularly associated with keratitis. Restriction endonuclease analysis of whole-cell DNA is proposed as a valuable technique for detecting mitochondrial DNA RFLPs in the differentiation of morphologically identical Acanthamoeba strains and may therefore be useful in resolving the complex taxonomy of the genus, which has hitherto been founded on subjective morphological criteria.

Improving Feedback for Medical Students in a Family Medicine Clerkship: Evaluating medical student performance using frequent feedback

To evaluate whether feedback to medical students could be improved by asking teachers to complete a student performance rating form during a family practice clerkship, the authors had students and teachers fill out a questionnaire. Teachers in the intervention group reported observing students more frequently. Students' perceptions of feedback frequency correlated strongly with their ratings of feedback quality.

Genetic relationships among strains of avian Escherichia coli associated with swollen-head syndrome

Genetic diversity among 22 Escherichia coli strains isolated from chickens with swollen-head syndrome (SHS), an acute respiratory disease of domestic poultry, and 93 strains isolated from birds with colibacillosis was assessed on the basis of allelic variation at 20 enzyme-encoding loci detected by multilocus enzyme electrophoresis. SHS isolates from Spain and Canada were polymorphic at 14 loci and were classified into 19 multilocus genotypes, defining clones that differed on average at 34% of the loci. In most cases, SHS isolates of different clonal genotypes were distinct in O:H serotype and expressed different fimbrial antigens. Comparisons with 93 isolates obtained from birds with colibacillosis revealed enzyme polymorphisms at 17 of 20 loci, with an average of 3.5 alleles per locus. In the total sample, 56 clonal genotypes were distinguished, with 27 (23%) of the isolates belonging to one of three common clones. Both SHS and colibacillosis isolates were genetically diverse, with an average single-locus diversity of 0.36, indicating that a wide variety of naturally occurring bacterial clones is associated with these acute avian infections. Six previously defined groups of clones identified in diseased birds from the United States were represented in isolates from Spain, indicating that similar clones occur in widely separated geographic areas. In addition, one group of SHS isolates was closely related to a recognized widespread clone complex incriminated in human septicemia and meningitis. The results suggest that certain strains implicated in SHS infections belong to a clone complex whose members have special attributes that promote involvement in invasive diseases in humans and animals.

Helping Families Manage Eating Difficulties in the Toddler and Pre-schooler

Parents of toddlers and pre-schoolers often report "eating difficulties" to their family doctors. Most problems arise from a combination of the normal psychological development of children, their changing nutritional needs, and parental responses to these changes. During well child and episodic visits, family doctors can assess these issues by taking a careful nutritional history, charting growth and development, and exploring the role of the family in defining and coping with the problem. Management includes prevention through anticipatory guidance and general information, treating problems with specific suggestions, and ongoing support.

AIDS and the Family Physician: Survey of Practices in AIDS Counselling and HIV Antibody Testing

In January and February of 1988, a questionnaire was sent to family physicians affiliated with family practice teaching departments in Toronto to determine whether there was any consensus among family physicians as to which patients they counselled about AIDS and to whom they recommended antibody testing for HIV. Ninety-seven out of 126 questionnaires were answered, for a response rate of 77.0%. More than 90% of the physicians reported discussing AIDS and its prevention with patients in high-risk groups, sexual partners of such patients, and those with multiple sexual contacts. More than 90% recommended HIV antibody testing for patients in high-risk groups who requested it. For discussing AIDS with all sexually active patients, however, there was much less consensus in the reported physician practices.

Fluorogenic assay for differentiating Staphylococcus warneri and Staphylococcus hominis strains of bovine origin

A fluorogenic assay for the detection of beta-glucosidase was developed as part of a simplified conventional method to distinguish Staphylococcus warneri and Staphylococcus hominis isolated from bovine body sites. The assay is based on the fact that strains of S. warneri produce beta-glucosidase, while strains of S. hominis do not.

Differential control and calcium-dependence of production of endothelium-derived relaxing factor and prostacyclin by pig aortic endothelial cells

1. Production of endothelium-derived relaxing factor (EDRF) by primary cultures of pig aortic endothelial cells was assessed indirectly by measuring endothelial cyclic GMP content, and prostacyclin production was measured by radioimmunoassay of 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha). 2. The resting level of cyclic GMP fell significantly following removal of extracellular calcium (1 mM EGTA present), but elevations of cyclic GMP content induced by sodium azide (10 microM) or atriopeptin II (10 nM) were similar in the absence and presence of extracellular calcium. 3. Haemoglobin (10 microM) reduced the resting level of cyclic GMP in the presence, but not the absence of extracellular calcium. M&B 22,948 (100 microM), superoxide dismutase (30 u ml-1), bradykinin (0.1 microM), ATP (10 microM) and ionophore A23187 (0.1 microM) each induced an increase in endothelial cyclic GMP content that was reduced in the absence of extracellular calcium. 4. In cascade bioassay experiments using endothelial cells on microcarrier beads and perfused in columns, continuous infusion of bradykinin (0.1 microM) induced release of EDRF, assayed on rabbit aortic rings, that was maximal after 2 min and still detectable up to about 16 min. 5. In the presence of extracellular calcium, the time course of bradykinin (0.1 microM)-stimulated production of EDRF, assessed as endothelial cyclic GMP content was maximal within 1 min, declined thereafter, but was still significant after 30 min. Production of 6-keto PGF1 alpha, measured simultaneously rose rapidly but was complete within 3 min. 6. In the absence of extracellular calcium the resting endothelial content of cyclic GMP fell, but resting production of 6-keto PGF1 alpha was unaffected. 7. In the presence of TMB-8 (100 microM) resting endothelial content of cyclic GMP rose slightly, but production of 6-keto PGFg fell. The bradykinin (0.1 microM)-stimulated increase in cyclic GMP content was augmented, but the stimulation of 6-keto PGF1I production was blocked. Results from cascade bioassay experiments confirmed that TMB-8 (100 microM) did not inhibit bradykinin-induced production of EDRF. 8. The data suggest that resting production of EDRF but not prostacyclin is dependent upon the presence of extracellular calcium. Bradykinin-stimulated production of EDRF is sustained and requires the presence of extracellular calcium, but stimulated production of prostacyclin is transient and may result from discharge of an intracellular pool of calcium. 9. The vascular endothelial cell appears therefore to control differentially production of EDRF and prostacyclin.

Isolation and identification of coagulase-negative Staphylococcus species from bovine body sites and streak canals of nulliparous heifers

Heifers (n = 103) ranging in age from 1d to 2 yr were sampled to determine the coagulase-negative staphylococcal flora of haircoat, nares, vagina, teat skin, and streak canal. A total of 2706 staphylococal strains were identified from 3612 bacterial isolates. Other genera or groups identified included Bacillus, Micrococcus, Corynebacterium, and coliforms. Staphylococci were identified utilizing a simplified biochemical scheme. Staphylococcus xylosus, S. chromogenes, and S. warneri were the predominant species recovered from anatomic sites and streak canal. Staphylococcal strains identified from specific body sites (expressed as percentage of heifers harboring these species) were: nares 74% S. xylosus and 48% S. warneri; haircoat, 70% S. xylosus and 57% S. chromogenes; vagina, 60% S. chromogenes and 54% S. xylosus; teat skin 62% S. chromogenes and 61% S. warneri; streak canal 53% S. chromogenes, and 43% S. warneri. The prevalent staphylococcal strains identified differed from heifers in confined housing compared with heifers on pasture. Differences observed in distribution of Staphylococcus species among body sites, particularly those between teat skin and streak canal, suggest that establishment of staphylococcal microflora depends on the ability of a species to adapt to and colonize anatomic sites as well as on environmental conditions present.

The effects of salbutamol on blood pressure and heart rate in Large White and Pietrain-cross breeds of pig

The effects of the beta 2-agonist salbutamol, on pig heart rate and blood pressure were evaluated at the expected commercially used concentration of 3 ppm in final feed, and at three times this level. Salbutamol was administered to pigs previously fed on control diet ('naive'), and in a second study to pigs fed 3 ppm salbutamol for 19 days ('acclimatized'). Heart rate and blood pressure were measured in conscious 30 kg pigs before (pre-ingestive), during (ingestive) and after ingestion (absorptive) of feed containing 3 or 9 ppm salbutamol. To assess any interaction with 'stress genotype' pigs, measurements were performed in Large White and Pietrain-cross breeds. The mean preingestive heart rates for the Large White and Pietrain-cross pigs were 127 and 109 beats/min, respectively. The corresponding figures for mean arterial blood pressure were 121 and 122 mmHg. The act of ingesting control feed caused heart rate to rise by 36-39% and blood pressure to increase by 17-27%. During the absorptive phase for 'naive' pigs fed 3 ppm salbutamol in the diet, blood pressure fell 5-11% and heart rate increased 20-24%, reflecting a classical baroreceptor mediated response. At 9 ppm the fall in blood pressure of 5-11% was similar to that at 3 ppm, while the rise in heart rate was larger at 31-38%. The magnitude of the changes at both 3 and 9 ppm was less than that evoked by the act of ingestion, with the exception of the heart rate response in Large Whites at 9 ppm, which was similar. The responses of the two breeds were comparable, indicating that salbutamol is unlikely to exacerbate the cardiovascular responses seen in potentially stress-susceptible pigs. The acute changes elicited by 3 ppm salbutamol during the absorptive phase in 'naive' pigs were abolished or substantially less in acclimatized pigs, implying a tachyphylaxis to the agonist's actions. This was confirmed by 9 ppm of salbutamol increasing heart rate of 'acclimatized' Large Whites to the same degree as 3 ppm in 'naive' counterparts. The desensitization in Pietrain-cross pigs was even more marked with no increase in heart rate produced by 9 ppm salbutamol following acclimatization. These data, combined with the rapid tachyphylaxis of response, indicate that salbutamol at the intended commercial inclusion of 3 ppm will not compromise the cardiovascular stability of the growing pig at rest.

Topical antibiotics in the treatment of superficial skin infections in general practice--a comparison of mupirocin with sodium fusidate

A total of 413 eligible patients took part in an observer-blind randomised multicentre clinical trial in order to compare the clinical and bacteriological efficacy of mupirocin (Bactroban) ointment with sodium fusidate (Fucidin) ointment for treating superficial skin infections seen in general practice. Mupirocin was applied twice daily and sodium fusidate thrice daily for a period of 7 days. Both treatments were similarly effective with 97% patients treated with mupirocin and 93% patients treated with sodium fusidate responding. Mupirocin was significantly more effective in the treatment of acute primary skin infections and in the treatment of a subgroup of patients with impetigo (P less than 0.01). Of the organisms detected before treatment began, 93% were not found after treatment with mupirocin compared with 89% after treatment with sodium fusidate. Staphylococcus aureus and/or beta-haemolytic streptococci appeared to be eliminated in significantly more patients treated with mupirocin (96%) compared with those treated with sodium fusidate (88%), (P = 0.03). Both treatments were well tolerated.

A Comparison of Six Selective Media for the Enumeration and Isolation of Staphylococci 1

The efficacy of Baird-Parker agar, Baird-Parker agar with bacitracin (0.8 μg/ml), Baird-Parker agar supplemented with acriflavin (7 μg/ml), polymyxin (20 units/ml) and sulphonamides (55 μg/ml), KRANEP agar, mannitol salt agar, and Staphylococcus medium 110 agar for the isolation and enumeration of Staphylococcus species was investigated. Bovine blood agar was used as the control medium. Thirty-seven staphylococci strains representing 23 species and 19 non- Staphylococcus species were tested. None of the six selective media supported the growth of all 37 Staphylococcus strains. The number of Staphylococcus species that grew on a specific medium ranged from only the S. aureus strains on Baird-Parker agar supplemented with acriflavin, polymyxin, and sulphonamides, to all but S. warneri BG 647 on Staphylococcus medium 110 agar. Strains of Bacillus , Corynebacterium , and Micrococcus grew on all six selective media.

Fetal assessment in the third trimester

Fetal health in the third trimester is assessed by means of clinical, ultrasound, biochemical, and biophysical techniques. Clinical examination and prenatal risk scoring should be performed at every prenatal visit. Fetal movement counting may be recommended to all pregnant women in the last trimester. A strategy is presented for use of the non-stress test and biophysical profile score for women at increased risk. Family physicians with a low-risk obstetrics practice must judge who should be referred for testing.

Role of infected food handler in hotel outbreak of Norwalk-like viral gastroenteritis: implications for control

Investigation of an outbreak of viral (Norwalk-like) gastroenteritis amongst staff (40 cases), resident guests (over 70 cases), and persons attending functions (54 cases) at one hotel over 8 days suggested that the main vehicle of infection was cold foods prepared by a food handler during and after a mild gastrointestinal illness. He was excreting Norwalk-like virus particles 48 hours after the illness. In addition, ill kitchen staff vomited in the kitchen area and may have contaminated surfaces and stored foods. It is recommended that food handlers should be regarded as potentially infectious until at least 48 hours after clinical recovery from viral gastroenteritis. Stored foods that may have been contaminated should be immediately discarded and areas of the work place which may have been affected should be identified and decontaminated.

Relationship of calf antibody status to disease and performance

Three tests were used to measure the circulating immunoglobulin in 381 purchased calves as they entered a commercial calf-rearing unit. A correlation of 0.64 was found between the zinc sulphate turbidity (ZST) test and a quantitative latex agglutination test (LAT) measuring IgG1 (P less than 0.001). A qualitative version of the LAT related poorly to the quantitative version. The proportion of plasma samples identified by the quantitative LAT as having an IgG1 concentration of less than 5 g/litre which were incorrectly identified as positives (greater than or equal to 5 g/litre) by the qualitative LAT was 0.65. The proportion of plasma samples identified by the quantitative LAT as having a IgG1 concentration of greater than or equal to 5 g/litre which were incorrectly identified as negative (less than 5 g/litre) was 0.11. There was no statistically significant relationship between plasma IgG1 concentration and initial liveweight, subsequent overall daily liveweight gain or disease incidence (P greater than 0.05). Calves treated for infectious disease, particularly respiratory disease after weaning, had statistically significantly lower liveweight gains than healthy calves (P less than 0.001).

Endothelium-derived relaxing factor and atriopeptin II elevate cyclic GMP levels in pig aortic endothelial cells

1. Two directly-acting stimulants of soluble guanylate cyclase, glyceryl trinitrate (0.1 microM) and sodium azide (10 microM), and a receptor-mediated stimulant of particulate guanylate cyclase, atriopeptin II (10 nM), each elevated the cyclic GMP content of primary cultures of pig aortic endothelial cells without affecting the cyclic AMP content. 2. Two receptor-mediated stimulants of adenylate cyclase, glucagon (1 microM) and isoprenaline (10 microM), had no effect on the cyclic AMP or cyclic GMP content of these cells, but the directly acting stimulant, forskolin (30 microM), induced a small increase in cyclic AMP content. 3. Three agents that release endothelium-derived relaxing factor (EDRF); bradykinin (0.1 microM), ATP (10 microM) and ionophore A23187 (0.1 microM), each markedly elevated the cyclic GMP content of pig aortic endothelial cells, but acetylcholine (1 microM) had no effect. None of these agents had any effect on cyclic AMP content. 4. Two agents that potentiate the actions of EDRF; M & B 22948 (100 microM) and superoxide dismutase (30 units ml-1), each elevated the cyclic GMP content of pig aortic endothelial cells without affecting the cyclic AMP content. Pretreating cells with catalase (100 units ml-1) did not affect the rise in cyclic GMP content induced by superoxide dismutase (30 units ml-1). 5. Pretreatment of pig aortic endothelial cells with haemoglobin (10 microM) reduced the resting content of cyclic GMP and blocked the increase in cyclic GMP content induced by glyceryl trinitrate (0.1 microM), sodium azide (10 microM), bradykinin (0.1 microM), ATP (10 microM), ionophore A23187 (0.1 microM), M & B 22948 (100 microM) and superoxide dismutase (30 units ml-1), but not that induced by atriopeptin II (10 nM). 6. Pretreatment of pig aortic endothelial cells with an inhibitor of soluble guanylate cyclase, methylene blue (20 microM), had no effect on the resting content of cyclic GMP. Methylene blue (20 microM) blocked the increase in cyclic GMP content induced by glyceryl trinitrate (0.1 microM), M & B22948 (100 microM) and bradykinin (0.1 microM), but not that induced by atriopeptin II (10 nM). 7. The data show that soluble guanylate cyclase, particulate guanylate cyclase and adenylate cyclase are present in pig aortic endothelial cells. They further suggest that EDRF, produced spontaneously or in response to vasoactive agents, elevates endothelial cyclic GMP content by stimulating soluble guanylate cyclase. It is possible that this may serve as a feedback loop by which the endothelial cell modulates EDRF production.

Effects of teat dipping on intramammary infections by staphylococci other than Staphylococcus aureus

Effects of intramammary infections in herds 1) either not teat dipping or postmilking teat dipping with either 2) linear dodecyl benzene sulfonic acid, 3) chlorhexidine, or 4) iodophor containing products were determined. Duplicate quarter foremilk samples were collected once from all lactating cows in 16 herds, four for each practice. Mean percentage of quarters infected with Staphylococcus species other than Staph. aureus was 11.0 in herds not teat dipping and 7.2 in herds teat dipping. Prevalence of Staphylococcus species intramammary infections in herds teat dipping with linear dodecyl benzene sulfonic acid was comparable to herds not teat dipping and greater than in herds using chlorhexidine and iodophor. The predominant Staphylococcus species in herds not teat dipping was Staph. epidermidis (37.1%). Staphylococcus hyicus constituted 48.5% of total Staphylococcus species intramammary infections in herds teat dipping and 12.4% in herds not teat dipping. Differences were not observed among SCC for quarters infected with different Staphylococcus species. Application of germicidal teat dips appeared to have selectively altered both prevalence and distribution of Staphylococcus species intramammary infections.

Effects of ischemic nerve block on the early and late components of the stretch reflex in the human forearm

To investigate the peripheral afferent mechanisms which mediate the short latency (M1) and long latency (M2) components of the stretch reflex, we have recorded EMG responses to extension perturbations at the wrist before and following inflation of a blood pressure cuff around the upper arm. After approximately 30 min of ischemia, the reflexes had almost completely disappeared, although subjects were still able to activate the forearm muscles voluntarily. As the ischemic block developed, the M2 component began to decrease in amplitude sooner than M1, and up to the time of complete loss of reflex activity, the suppression of M2 was relatively greater than that of M1. These results suggest that M2 may be mediated by a population of afferent fibers different from the Ia afferents which are believed to generate the M1 response.

The mechanisms by which haemoglobin inhibits the relaxation of rabbit aorta induced by nitrovasodilators, nitric oxide, or bovine retractor penis inhibitory factor

The mechanisms by which haemoglobin and methaemoglobin inhibit the vasodilator actions of glyceryl trinitrate, sodium azide, nitric oxide, and the bovine retractor penis inhibitory factor (IF) were studied on rabbit endothelium-denuded aortic rings. Methaemoglobin was less effective than haemoglobin against each vasodilator, it was more effective at inhibiting the relaxation to azide than that to glyceryl trinitrate. Glyceryl trinitrate was neither bound nor inactivated when passed through columns of haemoglobin-agarose or methaemoglobin-agarose. Azide was reversibly bound but less by haemoglobin-agarose than by methaemoglobin-agarose. Inhibition of the vasodilator actions of glyceryl trinitrate is not attributable therefore to a direct interaction with the haemoproteins, although a small part of the inhibition of azide-induced relaxation by methaemoglobin is likely to be due to a direct interaction. Columns of haemoglobin-agarose were more effective than columns of methaemoglobin-agarose in removing nitric oxide from solution. The greater ability of haemoglobin, compared to methaemoglobin, to inhibit vasodilatation induced by nitrovasodilators may therefore reflect the greater ability of haemoglobin to bind nitric oxide which is the active principle of the nitrovasodilators. Neither the acid-activated nor the inactive forms of IF were bound or inactivated when passed through columns of methaemoglobin-agarose. Neither form of IF was retained on passage through columns of haemoglobin-agarose, but the resulting activity in the eluates was less than control, was unstable and, unlike the original activity, decayed rapidly on ice. The greater ability of haemoglobin, compared to methaemoglobin, to inhibit vasodilatation induced by IF might therefore reflect the greater ability of haemoglobin to interact with this vasodilator and inactivate it.

Atriopeptin II-induced relaxation of rabbit aorta is potentiated by M&B 22,948 but not blocked by haemoglobin

We examined the effects of haemoglobin (which inhibits the vascular responses to stimulation of soluble guanylate cyclase) and of M&B 22,948 (which selectively inhibits cyclic GMP phosphodiesterase) on the relaxation induced in rabbit aorta by the atrial natriuretic peptide, atriopeptin II (which stimulates particulate guanylate cyclase). Pretreatment with M&B 22,948 (100 microM) produced a 2.3 fold potentiation of atriopeptin II-induced relaxation of endothelium-denuded rings of rabbit aorta. Pretreatment with haemoglobin (10 microM) had no effect on the relaxation or the 10.9 fold increase in cyclic GMP content induced by atriopeptin II in endothelium-denuded rings of rabbit aorta. The potentiation by M&B 22,948 suggests a causal role for cyclic GMP in mediating atriopeptin II-induced vasodilatation of rabbit aorta. The inability of haemoglobin to block the atriopeptin II-induced rise in cyclic GMP suggests that it does not block stimulation of particulate guanylate cyclase. Thus, it is unlikely that a ferrous haem-containing receptor site is involved in the activation of the particulate form of guanylate cyclase as it is with soluble guanylate cyclase.

Modification of motor output to compensate for unanticipated load conditions during rapid voluntary movements

Mechanisms responsible for load compensation during fast voluntary movements were investigated in 20 normal subjects trained to carry out rapid wrist flexions against a standard load. When an unanticipated increase in load occurred, there was a compensatory increase in agonist EMG and decrease in antagonist EMG. Unanticipated decreases in load produced reciprocal changes with a decrease in agonist EMG and an increase in antagonist EMG. The latency of these EMG changes was quite short and compatible with a spinal reflex mechanism rather than a long loop response. The results suggest that mechanisms exist at the spinal level to allow rapid modification of motor programs when unanticipated load conditions are encountered on initiation of movement.

Effect of induced hypomagnesaemia on the toxicity of imidocarb in calves

The hypothesis that the toxic effects of imidocarb mediated by reduced cholinesterase activity might be intensified by hypomagnesaemia was tested in calves. Hypomagnesaemia was induced in 12 males (50 kg) using an artificial milk based on a commercial nondairy coffee creamer. Although plasma magnesium levels reached 0.33 mmol litre-1 in two weeks no clinical signs were detected. In 12 control calves a daily magnesium supplement of 0.6 g was inadequate although the published requirement is 0.45 g; it was raised to 1.2 g to keep plasma magnesium normal. Lighter calves developed hypomagnesaemia more readily and fast-growing calves had lower plasma urea concentrations. Plasma calcium, but not plasma magnesium, showed significant positive correlation with plasma albumin. The only statistically significant effects of hypomagnesaemia were slight elevations of white cell count and plasma sodium. The hypomagnesaemic and normomagnesaemic calves were divided into two equal groups and treated with 3.3 mg kg-1 of imidocarb dipropionate or a placebo. The drug produced the expected clinical signs of mild toxicity and depression of cholinesterase but no other adverse effects. Transient slight depressions of plasma calcium and potassium concentration, a transient rise of plasma sodium and elevation of creatine kinase occurred. None of the effects of imidocarb treatment was intensified by hypomagnesaemia except, perhaps, constriction of the pupils; generally, hypomagnesaemic animals were affected less.

Influence of endothelium on drug-induced relaxation of the rabbit aorta

The influence of endothelium on relaxation induced by glyceryl trinitrate (GTN) and isoprenaline (I) has been studied in isolated rabbit aortic ring preparations, in the resting state and after constriction with 5-hydroxytryptamine (5HT). In resting preparations relaxant responses to GTN and I were smaller in the presence of endothelium. In preparations constricted with 5HT relaxant responses to GTN and I were conversely greater in the presence of endothelium. These paradoxical findings are discussed in relation to basal release of endothelium derived relaxant factor.

Evaluation of a rapid specific test for detecting colostral IgG1 in the neonatal calf

A commercially available latex agglutination test was used to measure the concentration of IgG1 in bovine plasma and the results were compared with radial immunodiffusion and zinc sulphate turbidity methods. For concentrations of IgG1 up to 80 g/litre there were highly significant (P less than 0.001) correlation coefficients between the latex agglutination test and radial immunodiffusion, and between the latex agglutination test and zinc sulphate turbidity method (0.93 and 0.74 respectively). The coefficient of variation for the latex agglutination test ranged from 8.1 per cent to 17.9 per cent. IgG1 concentration was measured using the latex agglutination test in whole blood on a farm, in whole blood at a laboratory and in plasma at a laboratory. The correlation coefficients were highly significant (P less than 0.001) in all cases. The latex agglutination test is easy to use, rapid and specific. It is suitable for checking the colostral status of young calves on commercial farms.

Identification of Naegleria fowleri in fresh isolates of environmental amoebae using a staphylococcal coagglutination technique

A coagglutination test using Staphylococcus aureus Cowan strain 1 sensitized with specific antiserum successfully identified Naegleria fowleri in axenic and monoxenic culture by detection of a heat stable antigen released into the culture medium during growth. Strong coagglutination, visible to the naked eye, occurred within 30 sec when the sensitized reagent was mixed on a slide with medium from N. fowleri cultures. N. lovaniensis gave a weak cross-reaction which developed over one min clearly distinguishable from that of N.fowleri.N.gruberi and N. australiensis gave no reaction. The technique is proposed as part of a rapid and economical scheme for detecting N. fowleri in environmental samples very soon after primary isolation, with distinct advantages over conventional methods. Further development of the technique to detect other Naegleria spp. and the early diagnosis of primary amoebic meningoencephalitis are suggested as future applications.

Rapid identification of thermophilic Naegleria, including Naegleria fowleri using API ZYM system

The suitability of the API ZYM system for identifying thermophilic Naegleria species, based on enzyme presence and activity, was investigated. Replicate testing on strains of N fowleri, N lovaniensis, and N australiensis cultured in a monoxenic and an axenic medium showed that the system could provide a rapid and reproducible means of identifying the species soon after primary isolation. No single enzyme was found specific for any one species, but considerable differences were found in the patterns of activity of acid phosphatase and leucine arylamidase. When these were compared the species could be differentiated. Use of the system in conjunction with a simple culture method is proposed as a readily available means of monitoring environmental and public bathing sites to prevent primary amoebic meningoencephalitis.

Human parvovirus arthropathy

19 of 153 patients attending an early-synovitis clinic were shown to have been recently infected by the human parvovirus (HPV). 5 other patients had evidence of some other closely preceding infection. HPV-infected patients typically presented with symmetrical peripheral polyarthropathy of sudden onset and moderate severity. Usually there was some improvement within 2 weeks, but in 17 patients symptoms persisted for more than 2 months, and in 3 for more than 4 years. Arthropathy in the absence of the facial rash that characterises HPV infection in children is a common presentation of the infection in adults.

Rapid thin layer chromatographic method for determination of zearalenone and zearalenol in grains and animal feeds

A rapid and inexpensive method has been developed for the analysis of zearalenone and zearalenol in grains and animal feeds. The method involves extraction with 75% methanol, precipitation of pigments with lead acetate, and defatting with petroleum ether. The mycotoxins are subsequently partitioned into toluene-ethyl acetate, chromatographed on high performance thin layer chromatographic plates, and detected after treatment with Fast Violet B salt solution. Sensitivity of the method is better than 80 ng/g for zearalenone and 200 ng/g for zearalenol. Ten samples can be completed in less than 2 h. The method is applicable for zearalenone in corn, wheat, barley, millet, and swine feeds.

Interactions of mothers with their newborns in the first half-hour of life

Eight first-time and eight second-time working class mothers were observed interacting with their newborn babies during the first half-hour of life. In all cases the father was present for at least some of this period. The interactions were notable for their passivity, mothers looked for long periods at their babies and engaged in some finger-tip touching of the babies face and head, but they engaged in very little exploration of the babies, few vocalizations and few expressive acts such as kissing. However, the presence of the father was associated with more intense mother-newborn interaction. First-time but not second-time fathers tended to be excluded from interaction with either the mother or the baby at this time. These results are discussed in the light of current thinking on mother-newborn bonding and the role of midwifery staff in promoting that bonding process.

Current maternal attitudes to infant feeding methods

Mothers' feeding practices and their attitudes to breast and bottle feeding were investigated. Sixty-four per cent started to breast feed and 35% continued past 2 months, a continuation rate which is higher than previously reported. Also higher than previously reported was the proportion of working class women breast feeding. This may reflect a current trend. Most women decided on their infant feeding technique early in pregnancy, and 80% followed that decision. For those who changed their minds about feeding practice postnatally, and for those who were initially undecided, the hospital was influential. Analysis of women's pleasurable and less restricting than they had anticipated. The results are discussed in relation to attempts to encourage breast feeding.

Laboratory screening for zearalenone formation in corn hybrids and inbreds

Grains from 14 corn inbreds and 4 single cross hybrids were inoculated with 3 isolates of Gibberella zeae to determine their inhibition of zearalenone production. The corn hybrids: Pa762 x A632 (50 mg/kg zearalenone production), A619 x A632 (17 mg/kg zearalenone production), H95 x Mo17 (132 mg/kg zearalenone production), and B73 x MO17 (33 mg/kg zearalenone production) appear to have less resistance than the inbreds to toxin formation. Inbred H95 (64 mg/kg zearalenone production) supported the highest toxin production of all inbreds. The remaining 13 inbreds did not exceed 15 mg/kg zearalenone production. The inbreds A632 (4 mg/kg zearalenone production) and Pa762 (2 mg/kg zearalenone production) demonstrated some resistance; the resulting cross, hybrid Pa762 x A632 (50 mg/kg zearalenone production), does have greater resistance than hybrid H95 x Mo17 (132 mg/kg zearalenone production). Analysis of variance indicated highly significant variation between corn varieties and fungal isolates. The coefficient of variation for 29 fermentations run in duplicate on inoculated control corn to produce zearalenone (212 mg/kg) was 37%, which would include variation in both the fermentation and analysis. Isolate and variety interaction is not significant.

The influence of ischaemia on the biliary tract

Damage of the biliary tract at the end of a period of hepatic preservation prior to liver transplantation has been observed in man. This damage may be important in the development of early biliary complications. A model of hepatic biliary ischaemia in the pig has been developed which permits comparison between the influences of warm and cold ischaemic damage on the biliary tract. The major damage to the biliary tract in the pig in this model appears to occur after prolonged cold preservation.

Analysis of motor conduction velocity in the human median nerve by computer simulation of compound muscle action potentials

A digital computer was used to reconstruct compound muscle action potentials recorded from the human thenar eminence after stimulation of the median nerve. The programme allowed the following parameters to be varied: (1) the dimensions of a representative single motor unit potential; (2) the number of motor units in the muscle and the range and distribution of conduction velocities in their nerve fibres; and (3) the distance along the nerve from the point of stimulation to the muscle. The reconstructed compound muscle action potentials were similar to real compound potentials recorded from normal subjects. The number of single motor units and the range of conduction velocities required for the reconstruction correlated with quantitative histologic studies of the recurrent branch of the median nerve to the thenar muscles. By altering the distribution of conduction velocities it was possible to study the effect of abnormal patterns of nerve conduction on the configuration of the simulated compound muscle action potentials. It was found that abnormally slow conduction caused an increased discrepancy between the main parameters of compound potentials corresponding to stimulation of the nerve at proximal and distal sites. These observations suggest that a careful analysis of the differences between pairs of compound muscle action potentials may provide a method for more detailed assessment of conduction velocity in clinical studies of peripheral nerve disorders.

AN ELECTROMETRIC METHOD FOR DEFINING THE AREA OF BARK AFFECTED BY TAPPING HEVEA BRASILIENSIS

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