Meticillin-resistant Staphylococcus aureus transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions investigated using whole-genome sequencing

BACKGROUND

The role of meticillin-resistant Staphylococcus aureus (MRSA) colonization of healthcare workers (HCWs), patients and the hospital environment in MRSA transmission in non-outbreak settings is poorly understood.

AIMS

To investigate transmission events (TEs) involving HCWs, patients and the environment under non-outbreak conditions in a hospital with a history of endemic MRSA using whole-genome sequencing (WGS).

METHODS

HCW (N = 326) and patient (N = 388) volunteers on nine wards were tested for nasal and oral MRSA colonization over two years. Near-patient environment (N = 1164), high-frequency touch sites (N = 810) and air (N = 445) samples were screened for MRSA. Representative MRSA and clinical isolates were analysed by WGS and core-genome multi-locus sequence typing (cgMLST). Closely related isolates (≤24 allelic differences) were segregated into related isolated groups (RIGs).

FINDINGS

In total, 155 MRSA were recovered: clinical isolates (N = 41), HCWs (N = 22), patients (N = 37), environmental isolates (N = 55). Nine clonal complexes (CCs) were identified among 110/155 MRSA sequenced with 77/110 assigned to CC22. Seventy-nine MRSA segregated into 17 RIGs. Numerous potential TEs were associated with CC22-MRSA (RIGs 1-15), CC45-MRSA (RIG-16) and CC8-MRSA (RIG-17). RIG-1, (the largest RIG) contained 24 ST22-MRSA-IVh from six HCWs, six patients, four clinical and eight environmental samples recovered over 17 months involving 7/9 wards. TEs involving HCW-to-patient, HCW-to-HCW, patient-to-patient and environmental contamination by HCW/patient isolates were evident. HCW, patient, clinical and environmental isolates were identified in four, nine, seven and 13 RIGs, respectively, with 12/13 of these containing isolates closely related to HCW and/or patient isolates.

CONCLUSIONS

WGS detected numerous potential hospital MRSA TEs involving HCWs, patients and the environment under non-outbreak conditions.

Toxigenic Corynebacterium ulcerans associated with upper respiratory infections in cats and dogs

OBJECTIVES

To describe infection in companion animals with the zoonotic pathogen Corynebacterium ulcerans and to determine its prevalence in clinically-affected and healthy animals.

MATERIALS AND METHODS

The clinical presentation and treatment of three cases of C. ulcerans infection is described. Two studies to determine C. ulcerans prevalence rates were undertaken: (a) a prospective study of nasal samples from healthy animals, 479 dogs and 72 cats; (b) a retrospective analysis of records of nasal samples collected over a 10-year period from 189 dogs and 64 cats affected by respiratory signs.

RESULTS

Toxigenic C. ulcerans was isolated from four cats with nasal discharge while concurrent C. ulcerans and mecC methicillin-resistant S. aureus infection was detected in a dog suffering from chronic nasal discharge. Clinical features were not distinctive and all cases recovered following antimicrobial treatment. Multilocus sequence typing supported a common source for isolates from the shelter cats. Carriage rates of C. ulcerans in healthy animals were 0.42% (2/479) in dogs and 0.00% (0/72) in cats whereas in animals with signs of upper respiratory tract infection prevalence rates were 0.53% (1/189) in dogs and 6.25% (4/64) in cats.

CLINICAL SIGNIFICANCE

Clinicians should be aware that dogs and cats can be infected with (or carriers of) toxigenic C. ulcerans Considering the potential zoonotic risk, assistance from medical and public health colleagues should be sought in confirmed cases.

The oral cavity revealed as a significant reservoir of Staphylococcus aureus in an acute hospital by extensive patient, healthcare worker and environmental sampling

BACKGROUND

Methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infection rates have risen steadily in recent years, with a marked decline in the corresponding rates due to methicillin-resistant S. aureus (MRSA). Screening for MSSA carriage is not routinely undertaken and MRSA screening is not universal, so the extent of S. aureus colonisation pressure in nosocomial settings is unknown.

METHODS

We conducted a prospective, observational study of patients and healthcare workers (HCWs) across nine inpatient wards in a tertiary referral hospital over a two-year period. Participants were screened for MSSA and MRSA using nasal swabs and oral rinses. Environmental surfaces and air were also tested for S. aureus using contact plates and active air sampling.

FINDINGS

We enrolled 388 patients and 326 HCWs; and took 758 contact plate samples from surfaces and 428 air samples. MSSA was recovered from 24% of patients, 31.3% of HCWs, 16% of air samples and 7.9% of surface samples. MRSA was recovered from 6.4% of patients, 3.7% of HCWs, 2.5% of air samples and 2.2% of surface samples. Inclusion of the oral cavity in addition to the anterior nares in the sampling regimen identified 30 patients and 36 HCWs who exhibited exclusive oral colonisation.

CONCLUSIONS

The oral cavity comprises a significant nosocomial reservoir for S. aureus that is currently under-appreciated. Oral screening should be considered both in terms of the colonisation pressure in a healthcare facility, and on an individual patient level, especially in patients where decolonisation attempts have repeatedly failed and those undergoing high risk procedures.

Substantial genetic divergence between morphologically indistinguishable populations of Fasciola suggests the possibility of cryptic speciation

The liver flukes, Fasciola hepatica and Fasciola gigantica, are considered to be sister species and between them present a major threat worldwide to livestock production. In this study sequence data have been employed from informative regions of the nuclear and mitochondrial genomes of over 200 morphologically F. hepatica-like or F. gigantica-like flukes from Europe, sub-Saharan Africa and South Asia to assess genetic diversity. Evidence is presented for the existence of four well-separated clades: African gigantica-like flukes, Indian gigantica-like flukes, European hepatica-like flukes and African high-altitude hepatica-like flukes. Application of the Biological Species Concept to trematodes is problematic; however, the degree of separation between these groups was sufficient for them to be considered as distinct species using the four times rule for speciation.

The Nursing Observed Illness Intensity Scale (NOIIS)

Inpatient progress is monitored mostly via the observation conducted by nursing staff. These tend to be unstructured, vary in reliability between different staff members, and be dependent on what has been written in nursing notes. The Nursing Observed Illness Intensity Scale (NOIIS) was devised to provide a more objective measure of behavioural improvement and symptom reduction. The scale is completed by qualified nurses at the end of every shift, based on everyday nursing observation and interaction with patients, and scores are entered on a NOIIS 'temperature' chart. In this study, more than 6000 ratings were captured on 106 admissions to a psychiatric intensive care unit. Inter-rater reliability of the scale was found to be satisfactory, and validity against the Brief Psychiatric Rating Scale good. Scores were shown to relate to the social organization and treatment methods of the unit. Recovery curves differed significantly by diagnosis, with patients having schizophrenia showing the slowest improvement. From a clinical point of view, the NOIIS can be used to track progress, response to changes in treatment and readiness of the patient for discharge; aids staff deployment; and can be used for clinical audit. For research, the scale can be used in clinical trials of treatment outcomes.

The measurement of psychotic acuity by nursing staff

Accurate evaluation of patients' psychotic state is essential to decrease psychotic symptoms and protect the patient and others. The aim of this paper is to conduct a literature review in order to access the utility, reliability and validity of current rating scales that are purported to measure psychotic acuity of inpatient population. A search of a number of electronic databases was undertaken to retrieve potential articles that focus on the measurement of acute psychosis. We identified some conceptual and theoretical problems when using a scale that is monitoring the progress of discharge and assesses the outcome of treatments. The findings revealed a difficulty in finding a commonly agreed definition of acute psychosis and a problem of obtaining frequent measures, and the frequency of measurement and fluctuation in psychosis. The most dominant scales in assessing psychosis were reviewed: the Global Assessment of Functioning Scale, the Brief Psychiatric Rating Scale and the Positive and Negative Symptom Scale. Several issues related to the scales' inter-rater reliability and construct validity remain unexplored. None of these scales addressed the conceptual and theoretical problems that we identified. A new scale that will measure acuity of symptoms in inpatient settings needs to be created.

A replication study of the City nurse intervention: reducing conflict and containment on three acute psychiatric wards

Conflict and containment on acute inpatient psychiatric wards pose a threat to patient and staff safety, and it is desirable to minimize the frequency of these events. Research has indicated that certain staff attitudes and behaviours might serve to accomplish this, namely, positive appreciation, emotional regulation and effective structure. A previous test of an intervention based on these principles, on two wards, showed a good outcome. In this study, we tested the same intervention on three further wards. Two 'City nurses' were employed to work with three acute wards, assisting with the implementation of changes according to the working model of conflict and containment generation. Evaluation was via before-and-after measures, with parallel data collected from five control wards. While simple before-and-after analysis of the two experimental wards showed significant reductions in conflict and containment, when a comparison with controls was conducted, with control for patient occupancy and clustering of results by ward, no effect of the intervention was found. The results were therefore ambiguous, and neither confirm nor contradict the efficacy of the intervention. A further intervention study may need to be conducted with a larger sample size to achieve adequate statistical power.

Should we be 'pushing meds'? The implications of pharmacogenomics

Medication continues to be the most widely prescribed treatment in the NHS for mental health problems. It has been known for many years that individuals differ in the way they respond to a given pharmaceutical therapy, and one reason for this lies in the genetic variation between individuals. This paper recognizes the impact that pharmacogenomics and pharmacogenetics are having in the field of mental health. Variants in genes that code for the drug metabolizing enzymes in the liver have been found to influence the way in which these enzymes handle psychotropic medication. Individuals can be classified as poor, moderate or extensive metabolizers when standard regimes are used, and this can lead to huge differences in therapeutic effect and toxicity. There are now genotyping tests available which provide information on the individual's ability to metabolize psychotropic medication. One author provides an account of the effects of medication on her son's physical and psychological well-being. Genotyping provided evidence for his poor metabolism of psychotropic medication, and his life is now changing as he is being very gradually weaned off this medication. This emerging field of work has implications for the way in which practitioners consider medication adherence.

Constraints and blocks to change and improvement on acute psychiatric wards--lessons from the City Nurses project

Recent years have seen sustained criticism and inspection of acute inpatient psychiatric wards, with the publication of reports and research leading to policy developments and a variety of efforts to improve perceived deficits. The City Nurses project seeks to reduce levels of conflict and containment on acute wards through the placement of expert nurses on wards to assist with the implementation of changes according to a working model of conflict and containment generation, based on previous research. Evaluation has shown significant decreases in aggression, absconding and self-harm by patients. However, in the course of working with the wards, various constraints and blocks to change have been identified and we describe these in detail in this paper. Analysis of the fieldwork diaries of the two City Nurses identified that change was hindered by limited staffing resources, problems with the physical environment and other resources, insufficient beds and the process of bed management, hierarchical ambiguity and multidisciplinary issues, the overdemanding role of the ward manager, and pervasive anxiety about the potential for serious untoward incidents and their implications for staff. We argue that sustained positive change in acute inpatient psychiatry requires these underlying structural issues to be both acknowledged and, if possible, resolved.

Reflections on the process of change on acute psychiatric wards during the City Nurse Project

The intention of this paper is to discuss the process of therapeutic change on two acute psychiatric wards during a research project that aimed to reduce conflict and containment. Analysis of fieldwork notes, reflection, team discussion and supervision. The City Nurse Project successfully reduced patient aggression, self-harm and absconding. This paper reports on the reflections made over the course of the year as changes and developments to acute wards took place. Specifically discussed are the beneficial effects of an action research approach, the role of the City Nurse, support for ward managers, education and training, clinical supervision as well as difficulties and barriers to the overall process of change. At an interim stage of the project, the staff have shown a willingness to engage in efforts to change and improve two acute wards. This paper shows the potential to improve acute wards and produce positive outcomes using a working model.

Stage-specific differences in fecundity over the life-cycle of two characterized isolates of the liver fluke, Fasciola hepatica

The variability inherent in different isolates of Fasciola hepatica has been evident from reports in the literature but to date there has been no systematic examination of the relationship between these differences and the fecundity of the parasite. In this study we have attempted to remedy this situation by comparing the relative efficiencies with which 2 well-characterized isolates of the liver fluke (Oberon and Fairhurst) progress through both their definitive and intermediate hosts. We did not observe a reduction in fitness in the Oberon isolate which has been reported to be triclabendazole-resistant, compared to the triclabendazole-susceptible Fairhurst isolate, but considerable inter- and intra-isolate variability at different life-cycle stages was recorded. Thus the Oberon isolate gave 4-fold the number of cercariae when 100 snails were each challenged with a single miracidium and was more successful in establishing productive infections in rats. Fairhurst metacercariae excysted at a higher rate than those from the Oberon isolate and Fairhurst flukes produced 4-fold more eggs. The extent of the intra- and inter-isolate variability revealed in this work will provide a basis for the development of models of population dynamics aimed at predicting the response of the liver fluke to changing environmental conditions such as the use of anthelmintics or climatic change.

Preliminary outcomes of a trial to reduce conflict and containment on acute psychiatric wards: City Nurses

Acute psychiatric wards experience high levels of conflict behaviours (violence, absconding, self-harm, rule breaking and medication refusal) by patients. These events cause stress and injury to staff and patients. Their management through containment methods (e.g. sedation, restraint, seclusion) is contentious, and nurses are ambivalent about their use. The aim of this study was to reduce conflict and containment on two acute psychiatric wards through changes in nurses' beliefs, attitudes and practices. Two 'City Nurses' were employed to work with two acute wards for 1 year, assisting with the implementation of changes according to a working model of conflict and containment generation, itself based on previous research. Evaluation was via before-and-after measures. Statistically and clinically significant decreases in conflict occurred, with falls in aggression, absconding and self-harm. Ward atmosphere improved and nurse-patient interaction rates increased. There was no significant change in containment method use. Significant reductions in aggression, absconding and self-harm can be achieved on acute psychiatric wards. However, it does not appear that containment can be reduced, even through large reductions in conflict.

Meal pattern analysis of macronutrient intake after PVN norepinephrine and peripheral clonidine administration

Norepinephrine (NE) injected into the paraventricular nucleus (PVN) of the hypothalamus of rats is a potent stimulant of food intake, more specifically ingestion of the carbohydrate nutrient. In 2 experiments of the present study, this effect was found to be dose-dependent, and the effectiveness of NE in potentiating total food consumption was greatly reduced when the carbohydrate diet was removed. In addition, experiments using a computer-automated data acquisition apparatus were performed to characterize, in detail, the impact of PVN injection of NE and peripheral administration of the alpha2-noradrenergic agonist clonidine (CLON) on the macrostructure of feeding behavior in animals given 3 pure macronutrient diets. These 2 compounds, injected at the onset of the nocturnal feeding cycle, had very similar effects on meal patterns, with both affecting nutrient intake by increasing meal size and duration rather than by increasing meal frequency. They both affected primarily the first meal of the dark cycle, selectively enhancing carbohydrate ingestion by increasing Kcal intake, percent composition in the total diet and feeding time, and also by decreasing the satiating impact of this macronutrient. These stimulatory effects of NE and CLON on carbohydrate ingestion during the first meal were followed by complete recovery over the next 1 to 2 hours after injection. In addition to these predominant effects on carbohydrate intake, PVN NE at the highest doses tested (10 and 20 nmoles) produced a small increase in fat intake, whereas peripheral CLON actually decreased intake of fat and protein over the 12-hour cycle. The similarities in the impact of NE and CLON on carbohydrate feeding patterns support the hypothesis that both agonists may be acting via the same PVN alpha2-noradrenergic system controlling ingestion of the carbohydrate-rich meals which predominate at dark onset.

Treatment gap in the use of lipid-lowering drug therapy in diabetes: a population-based study

BACKGROUND

Lowering cholesterol is highly effective in reducing morbidity and mortality in high-risk people with prevalent cardiovascular disease.

AIMS

To investigate lipid-lowering therapy use for secondary prevention of coronary heart disease in all diabetic patients in Tayside, Scotland.

METHODS

Among the 385,500 Tayside residents on 31 March 2001, the DARTS database identified all people with Types 1 and 2 diabetes with prevalent macrovascular disease, defined as a history of angina or coronary heart disease. The uptake of lipid-lowering drug was ascertained from MEMO's database of prescriptions dispensed at Tayside pharmacies.

RESULTS

Among the 1128 Type 1 patients, 11.3% had prevalent macrovascular disease and 7.9% used lipid-lowering therapy with 42.2% for patients with macrovascular disease. Current/former smokers (OR 2.40, 95% CI: 1.15-5.03) and those with a history of coronary heart disease (OR 2.26, 95% CI: 1.04-4.90) were more likely to use lipid-lowering therapy. Among the 8686 Type 2 patients, 38.8% had prevalent macrovascular disease and 18.3% used lipid-lowering therapy, with 26.7% for patients with macrovascular disease. Current/former smokers (OR 1.37; 95% CI 1.17-1.61) and those with a history of coronary heart disease (OR 2.07, 95% CI 1.66-2.59) or angina (OR 1.30, CI 1.03-1.63) were more likely to use lipid-lowering therapy. A duration of 4 years or less from the first macrovascular event was associated with increased use (OR 1.27; 95% CI 1.05-1.54). Age > 70 years reduced the likelihood (OR 0.51, CI 0.44-0.60).

CONCLUSION

A clear gap exists between those requiring lipid-lowering drug therapy and those who are actually receiving it in Tayside.

Are preventive drugs preventive enough? A study of patients' expectation of benefit from preventive drugs

OBJECTIVES

The study aimed to find the threshold of benefit for a hypothetical cholesterol-lowering drug below which the subject would not be prepared to take the drug. We also looked at whether proximity to the target event (myocardial infarction) and the subjects' views on drug taking affected this threshold.

DESIGN

We studied 307 subjects using a written questionnaire and interview. Group 1 (102 subjects) had just been discharged from the coronary care unit. Group 2 (105 subjects) were taking cardio-protective drugs but had no recent history of myocardial infarction. Group 3 (100 subjects) had no history of myocardial infarction and were taking no cardio-protective drugs.

RESULTS

Median values for the threshold of benefit below which the subject would not take the preventive drug were 20%, 20%, and 30% absolute risk reduction for Groups 1, 2 and 3 respectively. Median values for expectation of average prolongation of life were 12, 12 and 18 months respectively. Only 27% of subjects would take a drug offering 5% or less absolute risk reduction over five years. Subjects' views on medicinal drug taking in general and proximity to the target event were predictors of the acceptance of preventive drugs. Eighty percent of subjects wished to be told the numerical benefit of a preventive drug before starting on it.

CONCLUSION

For the majority, the expectation of benefit from a preventive drug is higher than the actual benefit provided by current drug strategies. There is a tension between the patient's right to know about the chance of benefiting from a preventive drug and the likely reduction in uptake if they are so informed.

Studies on the immunoglobulin E responses to Teladorsagia circumcincta in sheep: purification of a major high molecular weight allergen

Studies on the immunoglobulin (Ig)E immune responses to the gastric nematode, Teladorsagia circumcincta, have demonstrated a major high molecular weight allergen (HMWTc). Cross reactive allergens of similar MW were demonstrated for Trichostrongylus colubriformis and Cooperia curticei, but not for Haemonchus contortus. Purification of HMWTc was achieved by gel-filtration chromatography, and nonreducing SDS-PAGE and Western blot analysis revealed two closely associated bands with a molecular weight of approximately 140-150 kDa. Reduction showed four IgE reactive bands of 120, 50, 45 and 30 kDa, and deglycosylation abrogated the immunoreactivity of the 120 and 30 kDa bands. Ultrastructural immunolocalization by electron microscopy revealed that the IgE reactivity was confined to the cuticular surface of the infective (L3) larvae. ELISA studies to determine the IgE anti-HMWTc responses in lambs during their first grazing season, demonstrated significantly higher IgE antibody in lambs with low accumulative faecal egg count (FEC) compared to animals with high accumulative FEC. These studies provide evidence for a protective function of IgE antibody in Teladorsagia infections in lambs.

PathworX: an informatics tool for quality improvement

To optimize quality of care while conserving resources requires the right information and the right organizational processes. PathworX, a care management and documentation system developed at Vanderbilt, coordinates interdisciplinary care based on evidence-based best practices and provides information about the achievement of patient care goals as an indicator of quality. Using data about goal achievement and resource consumption in a process of continual quality improvement enables hospital units to reduce waste while improving patient outcomes.

High prevalence of primary aldosteronism in the Tayside hypertension clinic population

Primary aldosteronism (PA) was thought to be rare but recent evidence from Australia suggests that it may be more common. As this has important implications in terms of hypertension management, we undertook to screen for this treatable condition in our hypertension clinic. We obtained blood samples in sequential patients referred for assessment in our hypertension clinic in Tayside for plasma renin activity (PRA) and aldosterone. The aldosterone to PRA ratio (ARR) was used as an initial screening test to identify potential patients with PA. Those patients with an elevated ratio (> or =750) were admitted for the salt loading and fludrocortisone suppression test. These patients also underwent adrenal CT scanning, and in selected patients, adrenal scintigraphy. Between May 1995 and January 1997 (21 months), we screened a total of 495 patients. ARR was available in 465 (93.9%) patients. Out of that number, 77 (16. 6%) had an elevated ratio of > or =750, five of whom had an adrenal adenoma (one had previous adrenalectomy). Forty-five of these patients were admitted for the salt loading and fludrocortisone suppression test with 41 positive test results suggesting PA. One patient with a negative salt loading test result however had an adenoma proven on histology. A total of 43 cases of PA were identified, giving a minimum prevalence of 9.2% (43/465). Potentially the prevalence may be up to 15% assuming that the ARR has a sensitivity of 93% (42/45) in predicting PA. In conclusion, about one in 10 patients attending a hypertension clinic may have PA. This suggests that the prevalence of PA in Tayside is as high as that in the Australian hypertensive population, and this is likely to be true elsewhere, with obvious important implications for hypertension management.

Clinical and biochemical determinants of plasma lipid peroxide levels in type 2 diabetes

The enhanced risk and increased severity of atheroma in diabetes is well recognized but, as yet, incompletely explained. A cross-sectional study of vascular disease risk factors in a group of type 2 diabetic patients from South West Scotland has revealed an association between glycaemic control, assessed by HbAl level and plasma lipid peroxides measured by a specific high-performance liquid chromatography method. Duration of diabetes appeared to be a subsidiary contributor to lipid peroxidation. We suggest this evidence supports the importance of glycaemic control in modulating glyco-oxidative mechanisms probably crucial to production of diabetic complications. Atherosclerosis prevention in diabetes may hinge on exemplary simultaneous control of both hyperglycaemia and hyperlipidaemia.

Providing information to carers of people admitted to psychiatric hospital

Relatives have an increasingly important role in providing care in the community to people with mental health problems, yet numerous studies have highlighted a lack of support from health care professionals. GERARD LEAVEY and colleagues describe a study to investigate the information provided to relatives of patients in one trust, and suggest solutions to the ethical and professional dilemmas raised.

Providing information to carers of people admitted to psychiatric hospital

Relatives have an increasingly important role in providing care in the community to people with mental health problems, yet numerous studies have highlighted a lack of support from health care professionals. GEOFF BRENNAN describes the findings of a study to investigate the information provided to relatives of patients in one trust, and suggests solutions to the ethical and professional dilemmas raised.

Meal patterns of macronutrient intake in rats with particular dietary preferences

In the present study, we examined, via computer-assisted analyses, the nocturnal meal patterns of male albino Sprague-Dawley rats with clear differences in their individual preferences for the macronutrients, protein, carbohydrate, and fat. Rats exhibiting a strong preference for the carbohydrate diet over the 12-h nocturnal cycle (approximately 50% of the group) consumed fewer total calories and relatively small, more frequent meals, compared with rats that preferred protein or fat. Moreover, the first meal of the feeding cycle was identified as being most distinctive in reflecting the individual dietary preferences of these rats. This contrasts with the subsequent meals, which for all rats showed a general trend of increasing proportions of protein and fat and a decreasing concentration of carbohydrate. Only the high-fat rats (approximately 30% of the group) were further distinguished by a particularly large fat-predominant meal in the middle-dark period, which was then followed by smaller fat-rich meals in the late-dark period. These fat-preferring rats exhibited significantly greater body weight gain compared with rats preferring carbohydrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification of a cathepsin L-like proteinase secreted by adult Fasciola hepatica

A cysteine proteinase released in vitro by Fasciola hepatica was purified to homogeneity by Sephacryl S-200 gel filtration chromatography followed by QAE-Sephadex chromatography. The purified enzyme resolves as a single band with an apparent molecular size of 27 kDa on reducing SDS-polyacrylamide gel electrophoresis; however, under non-reducing conditions it migrates as multiple bands, each with enzymatic activity, in the apparent molecular size range 60-90 kDa. The sequence of the first 20 N-terminal amino acids of the enzyme shows considerable homology with cathepsin L-like proteinases. Immunolocalisation studies revealed that the cathepsin L-like proteinase is concentrated within vesicles in the gut epithelial cells of liver fluke.

Vascular abnormalities in non-insulin-dependent diabetes mellitus identified by arterial waveform analysis

PURPOSE

The arterial pressure waveform is derived from the complex interaction of the left ventricular stroke volume and the physical properties of the arterial circulation. Widespread abnormalities in the physical characteristics of the arterial vessels associated with diabetes mellitus can produce consistent changes in the shape of the pressure pulse waveform, providing information about arterial structure and tone that can be quantitated by pulse contour analysis.

PATIENTS AND METHODS

We analyzed intraarterial brachial artery waveforms in 28 patients with non-insulin-dependent diabetes mellitus and 22 control subjects matched for age and sex. A computer-based assessment of the diastolic pressure decay and a modified Windkessel model of the circulation were employed to quantify changes in arterial waveform morphology in terms of the large-artery compliance (C1), the oscillatory diastolic waveform (C2), inertance, and systemic resistance.

RESULTS

No differences were found in heart rate, mean arterial pressure, cardiac output, or stroke volume between groups. The mean oscillary arterial compliance estimate was significantly reduced in diabetic subjects versus controls: 0.02 (95% confidence interval [CI], 0.01 to 0.03) mL/mm Hg versus 0.08 (95% CI, 0.04 to 0.12) mL/mm Hg (p < 0.001). Oscillatory compliance values were uniformly reduced in the diabetic subjects regardless of the presence or absence of physical complications of the disease. No differences in large-artery compliance, inertance, or systemic resistance were found between groups. No positive correlations were found between indices of glycemic control, the known duration of diabetes, and any of the hemodynamic variables.

CONCLUSIONS

Quantitative changes in the arterial pressure pulse waveform, reflected by a reduced oscillatory compliance estimate, were found in patients with non-insulin-dependent diabetes mellitus. This estimate appears to act as an early marker for the vascular abnormalities associated with diabetes before complications of the disease become clinically apparent. By contrast, no changes in large-artery compliance were found in this patient population free from clinically obvious macrovascular disease.

Self-selecting albino rats exhibit differential preferences for pure macronutrient diets: characterization of three subpopulations

Analyses of natural feeding behavior in albino male Sprague-Dawley rats demonstrate that, when allowed to self-select from pure macronutrient diets (protein, carbohydrate and fat), these rats of the same genetic strain can be categorized into 3 subpopulations according to either their 24-h or their 12-h nocturnal patterns of nutrient intake. A majority of the animals (HC for high carbohydrate, 50% of the total population) consumed a diet rich in carbohydrate relative to protein or fat, while a smaller population of rats (HF, 30%) preferred the fat diet, and an even smaller population (HP, 20%) chose a high-protein diet. These 3 subpopulations, after a few weeks of maintenance on the diets, differed in their body weight, with the HF rats having a higher body weight than the HP animals, who tended to weigh more than the lightest HC rats. Whereas all subgroups exhibited a similar bimodal distribution of feeding during the nocturnal cycle, with peaks during the early and late dark periods, they were distinguishable on the basis of their nutrient consumption during specific phases of the dark cycle. This difference was most apparent in the early dark phase, when the 3 subgroups exhibited exaggerated preferences for the specific nutrient that was generally preferred over the 24-h cycle. This is in contrast to the middle dark phase, when diet preferences were attenuated or lost, and the late dark phase, when most rats were similar in showing an increased preference for protein and fat and a decreased preference for carbohydrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoradiometric assay of corticotropin with use of avidin-biotin separation

We have developed a "sandwich"-type immunoradiometric assay for corticotropin (ACTH), with a detection limit of 2 ng/L. Two antibodies are used: a mouse monoclonal antibody directed against ACTH[1-17] and labeled with 125I; and a purified polyclonal goat antibody directed against ACTH[34-39] and conjugated to biotin. We could separate 125I-labeled antibody bound to ACTH from 125I-labeled antibody not bound to ACTH by using an avidin-biotin bridge, with avidin bound to a polystyrene ball. This assay reacts with ACTH[1-39] but shows no reaction with ACTH fragments [1-24], [1-17], or [34-39], or with melanotropin, endorphins, or lipotropin. This assay is sensitive enough to detect ACTH in plasma of all normal adults. Concentrations measured in 94 adults between 0800 and 1000 hours were normally distributed on a log scale, with a mean of 19.5 ng/L and a 95% range of 7.1 to 53.8 ng/L. Dexamethasone given at 2300 hours to 14 adults suppressed ACTH to less than 4 ng/L in 13 of the subjects and to 8 ng/L in the 14th. Metyrapone given to 13 adults at 2300 hours increased ACTH to 245.3 ng/L (95% range, 90.1 to 667.7 ng/L). This assay accurately classified patients with disorders of the adrenal system.

Immunoradiometric assay of corticotropin with use of avidin-biotin separation

We have developed a "sandwich"-type immunoradiometric assay for corticotropin (ACTH), with a detection limit of 2 ng/L. Two antibodies are used: a mouse monoclonal antibody directed against ACTH[1-17] and labeled with 125I; and a purified polyclonal goat antibody directed against ACTH[34-39] and conjugated to biotin. We could separate 125I-labeled antibody bound to ACTH from 125I-labeled antibody not bound to ACTH by using an avidin-biotin bridge, with avidin bound to a polystyrene ball. This assay reacts with ACTH[1-39] but shows no reaction with ACTH fragments [1-24], [1-17], or [34-39], or with melanotropin, endorphins, or lipotropin. This assay is sensitive enough to detect ACTH in plasma of all normal adults. Concentrations measured in 94 adults between 0800 and 1000 hours were normally distributed on a log scale, with a mean of 19.5 ng/L and a 95% range of 7.1 to 53.8 ng/L. Dexamethasone given at 2300 hours to 14 adults suppressed ACTH to less than 4 ng/L in 13 of the subjects and to 8 ng/L in the 14th. Metyrapone given to 13 adults at 2300 hours increased ACTH to 245.3 ng/L (95% range, 90.1 to 667.7 ng/L). This assay accurately classified patients with disorders of the adrenal system.

Deletions extending from a single Ty1 element in Saccharomyces cerevisiae

Chromosomal rearrangements associated with one Ty1 element in the iso-1-cytochrome c (CYC1) region of Saccharomyces cerevisiae yeast cells were examined. Most of the rearrangements were deletions of the three linked genes, CYC1, OSM1, and RAD7, and resulted from recombination involving the single Ty1 element and a solo delta in the same orientation. These deletions differed by the number of Ty1 elements (zero, one, or two) remaining after deletion and by restriction site heterogeneities associated with these elements. A single Ty1 element remained at the deletion junction point much more frequently than no Ty1. Apparently the Ty1-associated delta element nearer to the solo delta was involved more often in recombination than the more distal Ty1-associated delta element. The restriction site data implicate gene conversion and suggest that site-specific recombination within the deltas, if occurring, is not the only mechanism of delta-delta recombination. Three other rearrangements bore deletions which began at the end of the Ty1 element and extended into regions not bearing Ty1 or delta sequences. Two of these deletions eliminated 7 kilobases of DNA, although they differed by an associated reciprocal translocation. The third involved a deletion of 14.7 kilobases of DNA associated with an overlapping inversion.

Yeast amber suppressors corresponding to tRNA3Leu genes

Amber suppressors previously isolated from the yeast Saccharomyces cerevisiae and belonging to the same phenotypic class (Liebman et al., 1976) were assigned to nine different linkage groups named SUP52 through SUP60. One of these suppressors, SUP52, had been shown to cause the insertion of leucine and had been genetically mapped (Liebman et al., 1977). The following additional amber suppressors were mapped: SUP53 maps near the centromere of chromosome III closely linked to leu2; SUP54 maps on chromosome VII, 6 cM distal to trp5; SUP56 maps on chromosome I, 5.4 cM distal to ade1; SUP57 maps on chromosome VI, closely linked to met10; and SUP58 maps on the left arm of chromosome XI, loosely linked to met14. We show by protein analysis that like SUP52, the suppressors SUP53 through SUP56 are leucine-inserters. Furthermore, by hybridization with a cloned tRNA3Leu probe we demonstrate that at least SUP53, SUP54, SUP55 and SUP56 contain mutations in redundant tRNA3Leu genes because they each generate a new XbaI site in a DNA fragment encompassing a tRNA3Leu gene. These new XbaI sites are predicted by the known sequences of tRNA3Leu genes if the CAA anticodon mutates to the amber suppressing anticodon CTA. It is likely that each of the nine suppressors in this phenotypic class contain similar mutations in different tRNA3Leu genes since we find that there are approximately nine unlinked redundant copies of tRNA3Leu genes in haploid strains.

Porous prostheses: an electron microscopic study

Proplast and Plastipore prostheses, removed at revision surgery, have been examined under the electron microscope. Foreign material in the multinucleated foreign body giant cells, previously reported under the light microscope, has been confirmed. The appearances were consistent with the conclusion that the giant cells were breaking down the prostheses by two different modes of action. X-ray elemental analysis is of limited value in this investigation because of the low atomic number of the elements involved. However, such analysis of this foreign material was consistent with the conclusion that it arose from the prosthesis.