Constructing an ELISA for Detection of Anti-Borrelia in Wildlife and Agricultural Animals

Zoonotic diseases have major impacts on human and animal health, as well as being ecologically significant. Lyme Borreliosis or Lyme disease, caused by infection by pathogenic members of the Borrelia genus, is among these zoonotic diseases. Serology is one of the most accessible means for indirect surveillance of pathogen presence by monitoring the presence, abundance, and type of immune response to the pathogen or pathogen-associated epitopes. Serological surveillance of wild animals is important as wild animals are the primary reservoirs of many zoonotic diseases. Similarly, serological surveillance of agricultural animals is important due to their economic importance, in addition to animal welfare concerns. However, serology in any non-model animal such as wildlife or agricultural animals is difficult because serology necessarily relies on blood samples from the animals being tested. While companion or laboratory animals are generally sufficiently accustomed to humans that blood samples can be obtained, obtaining blood samples from wild or agricultural animals is more challenging. This initial challenge is compounded by the absence of validated serological tools to evaluate antibody titres in the sera. In this chapter, we provide methods for constructing an ELISA for the detection of anti-Borrelia antibodies in non-model animals, using studies on horses and cows as a proof of principle. The methods focus on the problems specific to non-model animals including obtaining sera, options for determining positive and negative controls without the ability to perform controlled infections, and methods for test optimization and validation.

Doctors' experience of a bespoke physician consultation service: cross-sectional investigation

Aims and method

Our aim was to follow-up on a cohort of self-referred doctors who attended MedNet. We used a two-point cross-sectional design. Measures included three standardised self-report questionnaires administered before and after consultation. Doctors were also asked to complete a service user questionnaire, and data regarding engagement and onward referrals were gathered through case-note review.

Results

A statistically significant improvement in scores on all three questionnaires was found after intervention; however, scores on one subscale, the risk domain of the Clinical Outcomes in Routine Evaluation – Outcome Measure, did not change significantly. Of the doctors at no risk of suicide at intake, nearly two-thirds (n = 41/70, 59%) were sufficiently helped by the consultations provided to not need further treatment. Of the doctors at some risk of suicide at intake, two-thirds (n = 34/51, 67%) did need an onward referral. Only one doctor required hospital admission, an outcome that suggests the approach used is containing and clinically responsive.

Clinical implications

This paper highlights the efficacy, need and importance of specialist services for doctors in difficulty. We found that the bespoke consultation model provided at MedNet is valued highly by the doctors as service users.

Profile: Professor Ian Jones

Bespectacled Professor Ian Jones is an unpretentious, fluent and animated man with a dazzling set of credentials, including over 18500 citations of his research output.

Profile: Professor Philippa Garety

Healthy professional one-upmanship is exemplified in Philippa Garety's position as a professor of clinical psychology, a clinical director and a joint leader of a psychosis clinical academic group. Julia Bland sought to discover whether psychiatrists have anything substantial to offer that psychologists cannot.

A novel web-based tool for risk quantification and objectification of treatment of renal cell carcinoma

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Background: Despite the development of treatment guidelines, the management of renal cell carcinoma (RCC) remains overly subjective. Nomograms and statistical algorithms promise more objective decision making by patients and physicians by quantifying risk. Unfortunately, these tools remain underutilized in daily clinical practice because they are both cumbersome and time-consuming. We sought to create a novel website where all the available and relevant nomograms for RCC could be easily accessible for patients and practitioners, minimizing the subjectivity associated with clinical risk stratification and decision-making.

Methods: The existing literature was reviewed to identify published nomograms relevant to RCC. Nomograms were grouped by defining characteristics (preoperative versus postoperative predictive models, predictive models for metastatic disease, etc). Additional operationalized models included staging tools, surveillance models and cancer statistics. Nomograms were selected based on predictive accuracy, applicability, and ability to objectify risk stratification. Only nomograms with an AUC of greater than 0.7 were operationalized. The times required to extract clinical metrics for four hypothetical clinical scenarios were compared between the original paper version and our web-based model.

Results: www.cancernomograms.com organizes and operationalizes interactive predictive models for RCC for both physicians and patients. Each model was developed as an independent software program and deployed as an interactive flash object embedded in an HTML page allowing point of care risk calculation. In an initial sample of 15 subjects, the website decreased nomogram metric output from minutes to seconds, proving that utilization of a computer-based platform for these nomograms is faster (p=0.0003).

Conclusions: www.cancernomograms.com is a novel website that allows point of care risk quantification and objectified decision making using published statistical models. This web tool may help improve physician and patient communication and clinical care.

No significant financial relationships to disclose.

Wilson's disease in two siblings--one with fatal outcome

The clinical and biochemical findings in two siblings with Wilson's disease are described. One of them, an 11-year-old girl, developed acute liver failure terminating in death within a few weeks. Prior to her terminal illness she had been in good health without symptoms suggestive of Wilson's disease. Copper contents of urine, liver, kidney and brain were 20-100 times above the upper normal limits. The liver showed extensive micronodular cirrhosis with nonbile pigment deposits. Her 15-year-old brother had abnormal liver function tests with urinary copper excretion 20 times above the upper normal limit. Treatment with penicillamine was started. Following a short period of deterioration his condition has steadily improved.

Which doctors and with what problems contact a specialist service for doctors? A cross sectional investigation

BACKGROUND

In the United Kingdom, specialist treatment and intervention services for doctors are underdeveloped. The MedNet programme, created in 1997 and funded by the London Deanery, aims to fill this gap by providing a self-referral, face-to-face, psychotherapeutic assessment service for doctors in London and South-East England. MedNet was designed to be a low-threshold service, targeting doctors without formal psychiatric problems. The aim of this study was to delineate the characteristics of doctors utilising the service, to describe their psychological morbidity, and to determine if early intervention is achieved.

METHODS

A cross-sectional study including all consecutive self-referred doctors (n = 121, 50% male) presenting in 2002-2004 was conducted. Measures included standardised and bespoke questionnaires both self-report and clinician completed. The multi-dimensional evaluation included: demographics, CORE (CORE-OM, CORE-Workplace and CORE-A) an instrument designed to evaluate the psychological difficulties of patients referred to outpatient services, Brief Symptom Inventory to quantify caseness and formal psychiatric illness, and Maslach Burnout Inventory.

RESULTS

The most prevalent presenting problems included depression, anxiety, interpersonal, self-esteem and work-related issues. However, only 9% of the cohort were identified as severely distressed psychiatrically using this measure. In approximately 50% of the sample, problems first presented in the preceding year. About 25% were on sick leave at the time of consultation, while 50% took little or no leave in the prior 12 months. A total of 42% were considered to be at some risk of suicide, with more than 25% considered to have a moderate to severe risk. There were no significant gender differences in type of morbidity, severity or days off sick.

CONCLUSION

Doctors displayed high levels of distress as reflected in the significant proportion of those who were at some risk of suicide; however, low rates of severe psychiatric illness were detected. These findings suggest that MedNet clients represent both ends of the spectrum of severity, enabling early clinical engagement for a significant proportion of cases that is of importance both in terms of personal health and protecting patient care, and providing a timely intervention for those who are at risk, a group for whom rapid intervention services are in need and an area that requires further investigation in the UK.

Symptoms and anal sphincter morphology following primary repair of third-degree tears

Background

Approximately 0·6–9 per cent of vaginal deliveries are complicated by third-degree tears. The precise impact of such injuries on future pelvic floor function remains unknown. The aim of this study was to define the extent of structural and physiological damage to the anal sphincter and to investigate anorectal function in women who sustained third-degree tears during vaginal delivery.

Methods

Fifty-six women who sustained a third-degree tear were investigated prospectively. All patients had a primary repair of the anal sphincter complex, and were assessed by anorectal physiology and endoanal ultrasonography at a mean of 3·6 months. Symptoms were assessed by direct personal interview and also by a self-completed questionnaire.

Results

Forty-four patients had a persistent anal sphincter defect on ultrasonography. The mean resting and squeeze anal canal pressures were significantly lower in patients with a combined defect than in those in whom the repair was intact (P = 0·036 and P = 0·005 respectively). At direct interview three patients volunteered current symptoms of faecal and/or urinary incontinence whereas 32 reported bothersome symptoms on the questionnaire (P < 0·001).

Conclusion

The anatomical and physiological damage sustained during third-degree tears appears to be much greater than is generally appreciated. Primary repair does not provide lasting integrity. A self-administered questionnaire appears to be more accurate in defining the symptomatology.

Cumulative conception and live birth rates in natural (unstimulated) IVF cycles

IVF treatment, which involves ovarian stimulation, poses significant health problems such as ovarian hyperstimulation and is associated with a high incidence of multiple pregnancy and premature birth. In this paper, we demonstrate how natural cycle IVF is an effective and potentially cost-effective alternative treatment option for certain groups of infertile couples. The study was conducted in the Assisted Conception Unit at King's College School of Medicine, London. Fifty-two women with regular menstrual cycles whose partners had normal semen parameters were offered a total of 181 cycles of treatment (average 3.49 per couple). Life table analysis was used to calculate cumulative success rates after successive cycles of treatment. After four cycles, the cumulative probability of pregnancy was 46% with an associated live birth rate of 32%. To achieve maximal effectiveness, natural cycle IVF should be offered as a series of treatment cycles, for it is safer, less stressful and can be offered over consecutive cycles. Moreover, the avoidance of expensive drugs and reduced intensity of monitoring make natural cycle IVF less expensive than conventional treatment involving stimulation. We calculate that this treatment can be offered at approximately 23% of the cost of a stimulated cycle, suggesting that it may be a cost-effective alternative to conventional assisted conception techniques.

[Guidelines for resuscitation of newborn infants]

This article presents the new guidelines for resuscitation of the newborn from the European Resuscitation Council. It is estimated that, potentially, 800,000 newborns can be saved each year by simple airways manoeuvres. Personnel trained in basic resuscitation should be present at all deliveries and personnel trained in advanced resuscitation at deliveries with known risk factors. Attention to ventilation is of primary importance. Ventilation should be assisted if stimulation does not achieve a prompt onset of spontaneous respiration and/or the heart rate is less than 100 per minute. Chest compressions--1/3 of the anteroposterior diameter of the chest--should be provided if the heart rate is absent or remains < below 60 per minute despite adequate assisted ventilation for 30 seconds. Chest compressions should be coordinated with ventilation at a ratio of 3:1 and a rate of 120 "events" per minute to achieve approximately 90 compressions and 30 rescue breaths per minute. Adrenalin should be given if the heart rate remains below 60 per minute despite 30 seconds of effective ventilation and chest compression.

[Guidelines for cardiopulmonary resuscitation of children]

In this article the European Resuscitation Council's guidelines for basic and advanced resuscitation of children are presented. There are some changes from the previous guidelines. Children are divided in three age categories (in addition to the newly born): children up to one year old, one to eight years old, and more than eight years old. In Norway, but not in the rest of Europe, evaluation of the circulation by pulse check has been eliminated in basic, but not in advanced resuscitation. This is due to reports that pulse checks by lay rescuers require much time with poor specificity and sensitivity. In evaluating the patient's own ventilation, the differentiation between agonal gasps and regular breaths is stressed. ECG monitoring provides the link between paediatric basic life support and advanced life support. The algorithm for the latter closely resembles that proposed for adults. While there were previously three separate algorithms for ventricular fibrillation/ventricular tachycardia, asystole and electromechanical dissociation, there is now only one algorithm. Ventilation and chest compressions should be performed for one-minute periods with ventricular fibrillation/ventricular tachycardia, for three-minute periods with other rhythms.

Diffusion tensor MRI assesses corticospinal tract damage in ALS

BACKGROUND

A number of neurophysiologic and neuroimaging techniques have been evaluated in the research setting to assess upper motor neuron (UMN) damage in ALS. Changes in tissue structure in the CNS modify the diffusional behavior of water molecules, which can be detected by diffusion tensor MRI.

OBJECTIVES

To explore the hypothesis that degeneration of the motor fibers in ALS would be reflected by changes in the diffusion characteristics of the white matter fibers in the posterior limb of the internal capsule and that these changes could be detected by diffusion tensor MRI.

METHODS

We studied 22 patients with El Escorial definite, probable, or possible ALS-11 with limb onset (mean age 54.5 +/- 10.7 years) and 11 with bulbar onset (mean age 49.6 +/- 11.7 years)-and compared them with 20 healthy, age-matched controls (mean age 46.0 +/- 12.6 years). We assessed central motor conduction time (CMCT), threshold to stimulation, and silent period using transcranial magnetic stimulation. Diffusion tensor MRI was performed using a 1.5-T GE Signa system (Milwaukee, WI) fitted with Advanced NMR hardware and software capable of producing echo planar MR images. Data were acquired from seven coronal slices centered to include the posterior limb of the internal capsule. Maps of the mean diffusivity, fractional anisotropy, and T2-weighted signal intensity were generated.

RESULTS

There were no differences between the subject groups on measures of CMCT, threshold to stimulation, and silent period. However, the CMCT correlated with clinical measures of UMN involvement. We found a significant increase in the mean diffusivity and reduction in fractional anisotropy along the corticospinal tracts between the three subject groups, most marked in the bulbar-onset group. The fractional anisotropy correlated with measures of disease severity and UMN involvement, whereas the mean diffusivity correlated with disease duration.

CONCLUSION

The results support the use of diffusion tensor MRI in detecting pathology of the corticospinal tracts in ALS.

Limb contractures in levodopa-responsive parkinsonism: a clinical and investigational study of seven new cases

We describe six patients with classical levodopa-responsive Parkinson's disease (PD) and one case of levodopa-responsive familial juvenile dystonia-parkinsonism with fixed contractures of the hands, feet or legs. In most patients contractures became established over a short period (2 months-2 years) but a considerable time after onset of parkinsonism (mean 13 years). Mean disease duration was 17 years, and all patients had severe levodopa-induced dyskinesias, either biphasic or peak dose, in the affected limb prior to onset of the contracture. Nerve conduction studies excluded peripheral ulnar nerve lesions in all patients with one exception, who was found to have a mild bilateral ulnar entrapment neuropathy. Transcranial magnetic stimulation performed in five of the seven patients showed shorter mean central motor conduction time in the affected than in the unaffected limb. Results of magnetic resonance imaging of the brain performed in a subgroup of patients were normal, with no evidence to suggest multiple system atrophy, cerebral infarction or focal abnormalities of the basal ganglia. We conclude that hand and feet contractures are not necessarily restricted to parkinson plus syndromes and may complicate otherwise typical PD in the absence of a structural or peripheral nervous cause. Striatal dopaminergic deficiency, particularly long-standing, may have a role in the pathogenesis of limb contractures in PD.

[Characteristics of patients with domiciliary equipment for chronic respiratory diseases in Martinique]

The incidence of chronic respiratory failure is underestimated in Martinique. The aim of our retrospective study was to determine local particularities. Between December 1991 and December 1995, 128 patients (55% men, mean age 60 years, range 18-89 years) were hospitalized in our pneumology unit to receive a respiratory device (oxygen concentrator, respirator, continuous positive pressure generator). The high percentage of continuous positive pressure generators contrasted with the low number of oxygen concentrators prescribed indicating that obstructive disease is relatively less common due to the absence of widespread smoking habits. Sleep apnea syndrome (SAS) was particularly frequent in women (44% of the SAS patients). 10% of the SAS patients had perturbed blood gases unexplained by an associated bronchopathy. SAS in obese, hypertensive, diabetic women in Martinique is a public health problem and should be assessed by a prospective study. We observed that home care was particularly difficult for the most severely diseased patients, especially those with a tracheotomy, due to the lack of a management structure.

Protecting the world's children: the story of WHO's immunization programme

Systematic immunization on a worldwide scale was not officially recognized as a practical possibility until 1974, when WHO launched its Expanded Programme on Immunization. Today, 80% of the world's children receive this form of protection against childhood diseases during their first year of life. Coverage can reach 90% by the year 2000, the effectiveness of the vaccines used is improving, and vaccines against additional diseases are being added to the programme.

AIDS wasting syndrome as an enterometabolic disorder: the gut hypothesis

There is an interesting relationship between the HIV virus, the health of the gastrointestinal tract, and AIDS wasting syndrome, involving Tumor Necrosis Factor alpha (TNF alpha), specific and non-specific immunity in the gut, gut permeability, and oxidative stress. It is hypothesized that the progression of HIV to full-blown AIDS may be impacted by maintaining a healthy gut. A therapeutic protocol which decreases oxidative stress, inhibits TNF alpha, enhances phase I and II liver detoxification, and improves specific and non-specific immunity in the gut should be part of a therapeutic protocol for HIV-infected individuals. Through a better understanding of the pathophysiology of HIV advancing to AIDS, the practitioner can develop a treatment strategy of nutritional and lifestyle changes which could theoretically prevent an HIV infection from advancing to full-blown AIDS.

Paediatric life support. An advisory statement by the Paediatric Life Support Working Group of the International Liaison Committee on Resuscitation

This document reflects the deliberations of ILCOR. The epidemiology and outcome of paediatric cardiopulmonary arrest and the priorities, techniques and sequence of paediatric resuscitation assessments and interventions differ from those of adults. The working group identified areas of conflict and controversy in current paediatric basic and advanced life support guidelines, outlined solutions considered and made recommendations by consensus. The working group was surprised by the degree of conformity already existing in current guidelines advocated by the American Heart Association (AHA), the Heart and Stroke Foundation of Canada (HSFC), the European Resuscitation Council (ERC), the Australian Resuscitation Council (ARC), and the Resuscitation Council of Southern Africa (RCSA). Differences are currently based upon local and regional preferences, training networks and customs, rather than scientific controversy. Unresolved issues with potential for future universal application are highlighted. This document does not include a complete list of guidelines for which there is no perceived controversy and the algorithm/decision tree figures presented attempt to follow a common flow of assessments and interventions, in coordination with their adult counterparts. Survival following paediatric prehospital cardiopulmonary arrest occurs in only approximately 3-17% and survivors are often neurologically devastated. Most paediatric resuscitation reports have been retrospective in design and plagued with inconsistent resuscitation definitions and patient inclusion criteria. Careful and thoughtful application of uniform guidelines for reporting outcomes of advanced life support interventions using large, randomized, multicenter and multinational clinical trials are clearly needed. Paediatric advisory statements from ILCOR will, by necessity, be vibrant and evolving guidelines fostered by national and international organizations intent on improving the outcome of resuscitation for infants and children worldwide.

Isolation of an ovine pulmonary surfactant-associated anionic peptide bactericidal for Pasteurella haemolytica

Ovine pulmonary surfactant is bactericidal for Pasteurella haemolytica when surfactant and bacteria mixtures are incubated with normal ovine serum. To isolate this component, surfactant (1 mg/ml) was centrifuged at 100,000 x gav, and the supernatant was fractionated by HPLC. Fractions were eluted with acetonitrile (10-100%)/0.1% trifluoracetic acid and tested for bactericidal activity. Amino acid and sequence analysis of three bactericidal fractions showed that fraction 2 contained H-GDDDDDD-OH, fraction 3 contained H-DDDDDDD-OH, and fraction 6 contained H-GADDDDD-OH. Peptides in 0.14 M NaCl/10 microM ZnCl2 (zinc saline solution) induced killing of P. haemolytica and other bacteria comparable to defensins and beta-defensins [minimal bactericidal concentration (MBC)50 range, 0.01-0.06 mM] but not in 0.14 M NaCl/10 mM sodium phosphate buffer, pH 7.2/0.5 mM CaCl2/0.15 mM MgCl2 (MBC50 range, 2.8-11.5 mM). Bactericidal activity resided in the core aspartate hexapeptide homopolymeric region, and MBC50 values of aspartate dipeptide-to-heptapeptide homopolymers were inversely proportional to the number of aspartate residues in the peptide. P. haemolytica incubated with H-DDDDDD-OH in zinc saline solution was killed within 30 min. Ultrastructurally, cells contained flocculated intracellular constituents. In contrast to cationic defensins and beta-defensins, surfactant-associated anionic peptides are smaller in size, opposite in charge, and are bactericidal in zinc saline solution. They are members of another class of peptide antibiotics containing aspartate, which when present in pulmonary secretions may help clear bacteria as a part of the innate pulmonary defense system.

[Infantile hypertrophic pyloric stenosis]

We present 40 patients operated consecutively for pyloric stenosis during an 8-year period (1981-88). The most common symptom was projectile vomiting, which occurred in 92.5% of the cases. On examination only three patients had a palpable hypertrophic pylorus. In 39 patients, a preoperative x-ray examination with contrast was necessary to confirm the diagnosis. A pyleromyotomy was performed in all patients. We discuss the diagnostic routines and the results of our treatment.

Crystallographic characterization of conformation of 1-aminocyclopropane-1-carboxylic acid residue (Ac3c) in simple derivatives and peptides

The molecular and crystal structures of the C alpha,alpha-dialkylated alpha-amino acid residue 1-aminocyclopropane-1-carboxylic acid hemihydrate (H2+-Ac3c-O-.1/2 H2O) and nine derivatives and dipeptides have been determined by X-ray diffraction. The derivatives are pBrBz-Ac3c-OH, Piv-Ac3c-OH, Z-Ac3c-OH, the alpha-and beta-forms of t-Boc-Ac3c-OH, Z-Ac3c-OMe, and the 5(4H)-oxazolone from pBrBz-Ac3c-OH; the dipeptides are H-(Ac3c)-OMe and c(Ac3c)2. The values determined for the torsion angles about the N-C alpha (phi) and C alpha-C' (psi) bonds for the single Ac3c residue of Piv-Ac3c-OH, the alpha- and beta-forms of t-Boc-Ac3-OH and Z-Ac3c-OMe, and the C-terminal Ac3c residue of H-(Ac3c)2-OMe correspond to folded conformations in the "bridge" region of the Ramachandran map. The structures of pBrBz-Ac3c-OH and Z-Ac3c-OH, however, are unusual in having a semi-extended conformation for the phi, psi angles. The N-terminal Ac3c residue of H-(Ac3c)2-OMe adopts a novel type of C5 conformation, characterized inter alia by an (amino) N. . .H-N (peptide) intramolecular hydrogen bond. While the acyl N alpha-blocking groups form trans amides (pBrBz-Ac3c-OH and Piv-Ac3c-OH), the urethane groups may adopt either the trans [Z-Ac3c-OH and t-Boc-Ac3c-OH (alpha-form)] or the cis amide conformations [t-Boc-Ac3c-OH(beta-form) and Z-Ac3c-OMe]. The five- and six-membered rings of the 5(4H)-oxazolone and the 2,5-dioxopiperazine, respectively, are planar. The four independent molecules in the asymmetric unit of the free alpha-amino acid are zwitterionic.

L-656,575 (OCP-9-176): a novel oxacephem. Pharmacokinetics and experimental chemotherapy

L-656,575 is a new oxacephem that, based on studies in rhesus monkeys, is expected to have a moderately long half-life in humans. After administration of a 10-mg/kg dose by the intramuscular route to rhesus monkeys, peak serum concentrations of 32-54 micrograms/ml were seen at about 30 minutes, and the half-life was estimated to be 63 minutes. Urinary recovery of administered dose was greater than 94% in 6 hours. In mice given a 20-mg/kg dose by the subcutaneous route, a peak serum concentration of 22.9 microgram/ml was observed at 15 minutes after dosing, and the half-life in serum was about 18 minutes. Urinary recovery of the dose was 59% in 6 hours. In another study in mice, administration of probenecid did not extend the half-life of L-656,575, suggesting that the antibiotic is excreted primarily by glomerular filtration in this species. Binding to human plasma proteins was 30% at drug concentrations from 25-100 micrograms/ml. L-656,575 also was shown to be efficacious in experimental bacteremias due to Gram-positive and Gram-negative pathogens in mice, thus confirming the broad spectrum of activity demonstrated for L-656,575 in vitro.

Double peak attenuation method for estimating organ location

Radioactive sources of finite volume containing 133Xe, 67Ga, 99Tcm and 111In were used to measure the attenuation coefficient, mu, in water at six different energies in the range 80-296 keV using an Anger camera. The experimental accuracy was about 7% for the volume range from 40-225 ml when corrections were made for background. The same radioactive sources were used to measure zero attenuation count rates per unit of activity. The theoretical basis was also derived, which confirms our experimental findings, i.e. the measurement of the thickness of the attenuator using a dual energy method. The determination of the linear attenuation coefficient in the broad-beam geometry situation is possible by accounting for cross-talk, scatter and out-of-target activity. By correcting for the broad-beam geometry, agreement with the narrow-beam geometry linear attenuation coefficient was obtained. We also demonstrate the use of the technique to accurately determine the depth of the organ using two separate energies. This methodology is independent of the organ volume for determination of the depth. It is hoped that our findings will provide a better understanding of the photon interactions when extended sources are used. Such a knowledge can also be applied to organ volume measurements.

The osmotic thresholds for thirst and vasopressin release are similar in healthy man

The relationship between thirst perception and plasma osmolality was studied during hypertonic and physiological saline infusion in ten healthy volunteers. Thirst perception was quantified using a linear visual analogue scale which volunteers marked at intervals during the infusion periods. Infusion of hypertonic saline caused a steady rise in plasma osmolality together with a progressive linear increase in thirst perception and also plasma arginine vasopressin. No significant changes in thirst, plasma osmolality or plasma arginine vasopressin occurred during infusion of physiological saline. Linear regression analysis of the results defined the functions. Thirst (cm) = 0.3 (plasma osmolality-281) (r = +0.92, P less than 0.001) and plasma arginine vasopressin (pmol/l) = 0.4 (plasma osmolality-285) (r = +0.96, P less than 0.001). The osmolar threshold for thirst onset thus defined (281 mosmol/kg) was much lower than in previous studies and similar to the theoretical osmolar threshold for vasopressin release (285 mosmol/kg). We conclude that thirst perception rises in a progressive fashion throughout a wide range of plasma osmolality and that the osmolar threshold for thirst onset is similar to the theoretical osmolar threshold for vasopressin release. The results are compatible with the concept of either a single osmoreceptor subserving both thirst and vasopressin release, or two osmoreceptors sharing similar functional characteristics.

Early intimal lesions in the common carotid artery

Histological sections of the common carotid arteries from 259 children who were stillborn or died under 16 years of age were examined for intimal thickening, lamellar irregularities and ruptures, foam cells, and fat. Lesions were present at birth in approximately half the children examined, and the incidence increased rapidly in the first two months after birth. All the children had the early features of the prodroma of atheroma by 8 months of age. Compared with the findings of previous studies of the coronary arteries and aorta the histological findings appeared in the carotid arteries at an earlier age. The prevalence of intimal lesions in infant cot deaths, chronic diseases, and congenital heart disease was compared with that in all other children in the study. There was no difference in the cot death group, but in children under 2 years in both the chronic disease and heart deformity group there was a lower incidence of intimal thickening and visible fat.

Bioassay procedures for norfloxacin

A disk-diffusion bioassay procedure for the quantitation of norfloxacin in serum, tissue and urine employing Klebsiella pneumoniae ATCC 10031 was developed. When incubated at 28 degrees C, the assay has a sensitivity of 0.2 microgram/ml. Zones of inhibition on assay plates may be measured by hand (ruler, vernier caliper) or by automated image analysis. Urine samples require an initial 1:2 dilution in 0.1N HCl before assay to assure complete solution of the compound. Bioassay values in urine are comparable to those obtained by high performance liquid chromatography.