Evaluation of multiple frequency bioelectrical impedance and Cole-Cole analysis for the assessment of body water volumes in healthy humans

OBJECTIVE

To assess the application of a Cole-Cole analysis of multiple frequency bioelectrical impedance analysis (MFBIA) measurements to predict total body water (TBW) and extracellular water (ECW) in humans. This technique has previously been shown to produce accurate and reliable estimates in both normal and abnormal animals.

DESIGN

The whole body impedance of 60 healthy humans was measured at 496 frequencies (ranging from 4 kHz to 1 MHz) and the impedance at zero frequency, Ro, and at the characteristic frequency, Zc, were determined from the impedance spectrum, (Cole-Cole plot). TBW and ECW were independently determined using deuterium and bromide tracer dilution techniques.

SETTING

At the Dunn Clinical Nutrition Centre and The Department of Biochemistry, University of Queensland.

SUBJECTS

60 healthy adult volunteers (27 men and 33 women, aged 18-45 years).

RESULTS

The results presented suggest that the swept frequency bioimpedance technique estimates total body water, (SEE = 5.2%), and extracellular water, (SEE = 10%), only slightly better in normal, healthy subjects than a method based on single frequency bioimpedance or anthropometric estimates based on weight, height and gender.

CONCLUSIONS

This study has undertaken the most extensive analysis to date of relationships between TBW (and ECW) and individual impedances obtained at different frequencies ( > 400 frequencies), and has shown marginal advantages of using one frequency over another, even if values predicted from theoretical bioimpedance models are used in the estimations. However in situations where there are disturbances of fluid distribution, values predicted from the Cole-Cole analysis of swept frequency bioimpedance measurements could prove to be more useful.

Detection and widespread distribution of Chlamydia pneumoniae in the vascular system and its possible implications

AIMS

To attempt to detect Chlamydia pneumoniae DNA in atheromatous vascular tissue.

METHODS

A modification of an existing polymerase chain reaction (PCR) assay and immunofluorescence staining with a monoclonal antibody directed against C pneumoniae were used to detect C pneumoniae. Specimens from 32 patients undergoing abdominal aortic aneurysm repair were examined. Vascular tissue, ostensibly normal, from six liver transplant donors was also examined for comparison. Altogether, 43 vessels from these 38 subjects (age range 36-85 years) were examined.

RESULTS

C pneumoniae was detected in 11 (44%) of 25 aortas, five (55%) of nine iliac arteries, two (40%) of five femoral arteries, and one of two iliac veins. Immunofluorescence staining supported positive PCR results in three of 12 cases in which it was used. Overall, C pneumoniae was detected in the arteries of 14 (44%) of the patients undergoing vascular surgery and three (50%) of the donors.

CONCLUSIONS

This study is the first in the UK in which C pneumoniae organisms have been found in atherosclerotic vessels and the tendency for the organisms to be present most often in such vessels exhibiting chronic inflammatory changes suggests that a search for them in various forms of arteritis may also be rewarding.

Total hip replacement: the current perspective after 37 years

The first hip replacements of the modern era were performed by Sir John Charnley in 1959,using poly- tetrafluoroethylene for the acetabulum and polymethylmethacrylate cement to secure the stainless steel femoral component. These initial operations were not a success due to excessive wear of the PTFE bearing surface. The operation was not acknowledged to be the success it is today until 1962when Charnley switched to using high-density polyethylene for the acetabular component and the "low-friction arthroplasty" was introduced.' This prosthesis has remained the "gold standard" until the present day with relatively few changes to the original concept, and with considerable success with published results in excess of 20 years.'

Monitoring of extracellular and total body water during haemodialysis using multifrequency bio-electrical impedance analysis

Multifrequency bio-electrical impedance analysis (MFBIA) was evaluated as a technique for monitoring changes in extracellular and total body water (ECW and TBW, respectively) of 15 subjects during dialysis. Dilution analysis, using deuterium oxide and sodium bromide, was also performed on each subject before dialysis so that prediction equations for ECW and TBW based on the MFBIA measures could be developed. These prediction equations were then used to estimate water compartment volume changes during dialysis and compared with volumetric measures of the dialysate removed. The results show that MFBIA does not accurately measure ECW and TBW changes during dialysis. The MFBIA measures tend to overestimate the changes and are not sufficiently precise to be clinically useful.

Multiple frequency bioelectrical impedance for the prediction of total body potassium in cystic fibrosis

The use of multiple frequency bioelectrical impedance analysis (MFBIA) was compared with single frequency bioelectrical impedance analysis (SFBIA) and anthropometry to estimate the size of the body cell mass (BCM) in a paediatric cystic fibrosis population. BCM was independently determined from the accepted gold standard reference of total body potassium (TBK). MFBIA was used to measure the impedance of the body at 248 frequencies from 4 kHz to 1 MHz. Data were analysed using Cole-Cole plots of reactance versus resistance. The limits of agreement procedure was used to determine the reliability and precision of the different techniques to predict values for TBK, in an individual subject. The results indicate that MFBIA with a precision of 12% offers little improvement over single frequency BIA but is better and more accurate than anthropometry for the prediction of TBK in an individual patient.

Chlamydia trachomatis as a possible cofactor for Kaposi's sarcoma in AIDS

AIDS-associated Kaposi's sarcoma (KS) is much more frequent in patients acquiring HIV infection via the sexual route. Epidemiological studies have confirmed the likely involvement of a sexually acquired cofactor in the pathogenesis of this form of KS. We have formulated a set of postulates, epidemiological and experimental, to fit a single unifying hypothetical agent. Chlamydia trachomatis is one of 3 agents to fit the epidemiological criteria. Our data suggest a possible association between increased IgG serum antibody to C. trachomatis and the occurrence of KS. Conversely, higher titres of IgG serum antibody to C. pneumoniae were associated with the absence of KS. We feel that it is important to study further the relationship between C. trachomatis and KS.

The use of Cole-Cole plots to compare two multi-frequencybioimpedance instruments

Two commercially available multifrequency bioimpedance spectrometers (Xitron 4000B and SEAC SFB3) were compared by performing measurements on a set of electronic circuits and by studying 14 healthy volunteers. Output data were plotted as reactance versus resistance and fitted with a semi-circle using a least squares fitting program. In tests with six electronic circuits both instruments produced impedance loci that were well described by semicircular Cole-Cole plots, though there were some minor discrepancies using the Xitron instrument at frequencies above 150 kHz. When tested on the volunteers the SEAC instrument gave very good fits (RMSE = 1.5 Omega) to a semi-circle from 5-600 kHz on all volunteers. The Xitron instrument gave excellent fits to the semi-circle between 5 and 55 kHz (RMSE = 0.7 Omega) but above 55 kHz the phase measurements stayed constant or even increased, confirming the anomalous behaviour reported by other authors. The conclusions to be drawn are that the semicircular plots predicted by the Cole-Cole theory give a very good description of multifrequency impedance data recorded by the SEAC SFB3 instrument, on human subjects, for frequencies between 5 and 600 kHz. The Xitron 4000B is not able to reproduce the theoretically expected results in humans above 55 kHz.

Evaluation of a commercial polymerase chain reaction assay for Chlamydia trachomatis and suggestions for improving sensitivity

A commercial polymerase chain reaction (PCR) assay (Amplicor, Roche) for Chlamydia trachomatis was compared with a direct fluorescent antibody (DFA) test using urethral and cervical samples, many of which on the basis of prior testing by DFA contained small rather than large numbers of elementary bodies. Urine samples were collected from patients in a sequential unselected manner. Of 244 clinical specimens (138 male urethral and cervical; 106 male and female urine), 66 were positive by both DFA and PCR and 141 were negative by both tests. Nine samples were DFA negative and PCR positive, and 28 samples were DFA positive and PCR negative. However, 24 (86%) of the latter samples contained fewer than ten elementary bodies. When serial dilutions of laboratory stock strains (serovars E and H) were tested, the DFA test detected Chlamydia trachomatis at a dilution tenfold greater than the PCR. Furthermore, of five DFA-positive clinical samples, three that were PCR negative when tested according to the manufacturer's instructions were positive when they were diluted less. A modification of the PCR assay along these lines might improve sensitivity.

The location of sucrose synthase in root nodules of white clover

Immunogold labelling was used to identify the location of the sucrose hydrolytic enzyme sucrose synthase in the N₂ -fixing root nodules of white clover. This is the major enzyme of sucrose cleavage in clover nodules and might be involved in the modulation of N₂ fixation by controlling the rate of utilization of photosynthetic products. Knowledge of the precise cellular location of this enzyme in relation to the point of delivery (the vascular bundles) and the site of utilization of the catabolic product (malate in the bacteroids) might aid our understanding of the metabolic communication between different cell types of the nodule. Gold particle density was greatest in the cytosol of uninfected cells of the central region and in the layer of cortical cells in direct contact with infected cells. By contrast, relative gold particle density was 2-3 fold lower in the cytosol of infected cells. The distribution of sucrose synthase is discussed in relation to sucrose transport, starch metabolism and the provision of carbon and energy for N₂ fixation.

Nutritional growth retardation is associated with defective lung growth in cystic fibrosis: a preventable determinant of progressive pulmonary dysfunction

Evidence for a relationship between nutritional growth retardation in cystic fibrosis (CF) and progressive pulmonary dysfunction was evaluated by a prospective longitudinal study of changes in nutritional growth parameters, in relation to changes in pulmonary function data, in 61 moderately affected CF patients, aged 5-17 yr, during the equilibrated phase of lung growth. Age, sex, initial and serial weight and height Z scores, body cell mass (BCM) by total-body potassium (TBK) analysis, and changes in forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC), excluding data during pulmonary exacerbations, were analyzed by multiple regression analyses. The only significant predictor of change in FVC (best-fit model) was change in BCM, expressed as TBK (g/yr), TBK for age (percentage predicted), and TBK for height (percentage predicted) (p < 0.01). Standard anthropometric variables were not predictive. No reliable predictive model emerged for changes in FEV1. Relative decline in TBK for age was strongly predictive of decline in FVC (percentage predicted) accounting for 23% of this change. Patients with normal growth of the BCM had significantly less decline in FVC than those with retarded growth of the BCM (a fall of 2.5 vs. 6.8%/yr, p < 0.01). Impaired growth of the metabolically active BCM appears to be associated with progressive lung dysfunction in CF, possibly mediated by impaired lung growth. Achieving optimal nutrition and growth may minimize the progressive decline in pulmonary function commonly seen in this disease.

Future technologies

Research and development in the area of body composition has undergone considerable changes in the last decade. These changes have resulted in part from the improvement of established techniques-but also from the introduction of methods based upon principles new to body composition studies. One can observe in recent developments a trend towards less invasive techniques, and cheaper, more portable instrumentation. There has also been a move towards improving the efficacy of the information obtained. The trend towards less invasive techniques, which includes lower dose, is particularly important when considering applications involving children. The question of 'future technologies' needs to be considered against the background of these developments if one is to propose the direction of future research. This paper considers possible new and modified technologies which may find application in the measurement of body composition. In addition, currently emerging technologies which need further research and development will be discussed. Examples of technologies examined in this paper include: •a possible new approach to measurement of bone mineral density in neonates using laser beam transmission, •possible modification of dual-energy X-ray absorption (DEXA) techniques for improved precision in the measurement of the relative lean/fat component, and •the research required to validate the use of multifrequency bio-electrical impedance analysis for measurement of extracellular and total body water.

Leucine metabolism and body cell mass in cystic fibrosis

To further investigate the nature of malnutrition in cystic fibrosis (CF), specifically to evaluate the influence of body composition on leucine metabolism and determine whether measures used as reference standards alter comparative differences in protein metabolism, we measured [13C]leucine kinetics in nine well-nourished and eight malnourished, height-, FEV1-, and sex-matched CF subjects. Body cell mass was measured by total-body potassium (K40) analysis. Leucine turnover did not significantly differ between groups in absolute values or when corrected for body weight, body height, or surface area. However, malnourished CF patients had accelerated leucine turnover based on body cell mass measurements. Mean leucine synthesis per unit body cell mass in the malnourished group was 147% higher than that of the well-nourished group (p < 0.001). These data indicate that altered body composition is an important factor influencing protein metabolism in CF and should be considered in future metabolic studies. The importance of potentially serious but possibly correctable deficits in body cell mass in CF is emphasized.

Infrequent detection of Chlamydia trachomatis in a longitudinal study of women with treated cervical infection

OBJECTIVE

To determine how often Chlamydia trachomatis cervical infections are detected in women following completion of a currently recommended treatment regimen and the reason for recurrence.

METHODS

A longitudinal follow-up study of 43 initially C trachomatis-positive women for periods of up to two years.

RESULTS

C trachomatis was detected in three women, 19, 16 and about four months, respectively after completion of treatment. All specimens from the other 40 women which were taken during visits two to seven, that is periods of three to 700 days after treatment, were chlamydia-negative.

CONCLUSION

Although C trachomatis is usually eradicated from the genital tract by conventional treatment, occasionally it may be found again. It is difficult to determine whether detection after treatment is due to persistence or reinfection and further studies are required.

The role of Chlamydia trachomatis in urethritis and urethral symptoms in women

One hundred and fifty women who attended a genitourinary medicine clinic and who required a speculum examination were investigated to determine the association between Chlamydia trachomatis and urethral symptoms and signs. Those who had taken antibiotics with anti-chlamydial activity within 3 months or those who were menstruating, pregnant or using an intrauterine contraceptive device were excluded. C. trachomatis infection of the urethra, or infection of the urethra and cervix together, combined with each separately, were strongly associated with > = 5 polymorphonuclear (PMN) leucocytes per high-power field (x 1000) in a Gram-stained urethral smear (P < 0.00005 and P < 0.0005, respectively). This appeared not to arise from leucocyte contamination from the lower genital tract. However, C. trachomatis infection of the urethra was not associated with symptoms of dysuria or frequency. In conclusion, it seems likely that C. trachomatis infection of the urethra in women probably causes urethritis which is usually asymptomatic. Women who have objective evidence of urethritis might best be managed by appropriate antibiotic therapy and counselling, and advice that partners should attend for review.

Early pattern formation in the developing Drosophila eye

The formation of complex cellular arrays from unpatterned epithelia is a widespread developmental phenomenon. Insights into the mechanisms regulating this transformation have come from studying the development of the Drosophila compound eye. Pattern formation in the eye primordium is a highly ordered process in which the onset of differentiation is coordinated with synchronization of cell cycle progression. Recent studies have identified a number of genes that are required for early patterning events, and provide a link between the regulation of proliferation and pattern formation.

Limited value of two widely used enzyme immunoassays for detection of Chlamydia trachomatis in women

Enzyme immunoassays (EIAs) are widely used to diagnose chlamydial infections in patients attending genitourinary medicine clinics. They are relatively easy to perform and are suitable for testing large numbers of samples. The objective of this study was to determine what proportion of women with chlamydial infection, defined as the presence of Chlamydia trachomatis in a cervical smear or deposit and/or in the urinary tract, detected by means of a sensitive direct fluorescent antibody test could also be identified by using two commercially available EIAs to test cervical samples. On hundred fifty-one women attending the genitourinary medicine clinic at St. Mary's Hospital, London, were enrolled. The use of the Chlamydiazyme (Abbott Diagnostics, UK) and MicroTrak (Syva, UK) EIAs resulted in the identification of only 56% and 63%, respectively, of women with chlamydial infection detected by direct fluorescent antibody staining. Thus, the EIAs available for detection of chlamydiae in cervical samples are inadequate for identifying all infected women. Improvement might be achieved by testing multiple samples or by resorting to tests of greater sensitivity.

Cell cycle progression in the developing Drosophila eye: roughex encodes a novel protein required for the establishment of G1

The onset of pattern formation in the developing Drosophila eye is marked by the simultaneous synchronization of all cells in the G1 phase of the cell cycle. These cells will then either commit to another round of cell division or differentiate into neurons. Although cell cycle synchronization occurs in roughex (rux) mutants, cells circumvent G1 and all cells enter S phase, including cells that would normally differentiate. This leads to defects in early steps of pattern formation and cell fate determination. rux is suppressed by mutations in genes that promote cell cycle progression (i.e., cyclin A and string) and enhanced by mutations in genes that promote differentiation (i.e., Ras1 and Star). rux encodes a novel protein of 335 amino acids. We propose that rux functions as a negative regulator of G1 progression in the developing eye.

roughex is a dose-dependent regulator of the second meiotic division during Drosophila spermatogenesis

During spermatogenesis, germ cells execute two meiotic divisions, then withdraw from the cell cycle and initiate postmeiotic differentiation. We show that the gene roughex (rux) is a dose-dependent regulator of meiosis II during Drosophila spermatogenesis. rux mutant germ cells execute the two meiotic divisions, but then undergo an additional M phase resembling an extra meiosis II. Conversely, germ cells with excess rux function fail to undergo meiosis II. rux does not appear to act directly at meiosis II. Rather, rux appears to act through cyclin A during premeiotic G2 to regulate meiosis II. We propose that cyclin A-cdc2 kinase at the G2 to M transition of meiosis I activates a target necessary for meiosis II, thereby coupling the two meiotic divisions.

Clinical applicability of bioelectric impedance to measure body composition in health and disease

The applicability of bioelectric impedance analysis (BIA) as a measure of body composition in children and young adults in both health and disease was studied in 155 subjects (5 mo to 54 yr of age) who were healthy (n = 21), had cystic fibrosis (n = 16), or had end-stage liver disease with variable clinical ascites or edema (n = 62). BIA and phase angle measured at a frequency of 50 kHz between the wrist and contralateral ankle by use of a tetrapolar measuring technique was compared with fat-free mass (FFM) estimated from skin-fold (SK) thickness measurements (n = 57), and body cell mass (grams potassium) measured by total-body potassium (TBK) counting. In a subgroup of subjects with end-stage liver disease, BIA was compared with total-body water measured by deuterium dilution (n = 21). High levels of correlation were found in healthy subjects, cystic fibrosis patients, and patients with end-stage liver disease when impedance (height2/resistance) was used to predict TBK (r = 0.96, 0.96, 0.98, respectively), and SK was used to predict FFMs (r = 0.96, 0.99, 0.90, respectively), by linear regression analysis. However, less satisfactory relationships were found when the methods were more appropriately analyzed with an estimated limits of agreement procedure (1 SD = 8.5, 5.0, 27.7% [TBK] and 9.4, 6.7, 23.0% [FFMs], respectively). A poor level of technique agreement (1 SD = 14%) was found when this method was compared with total-body water measured by isotope dilution in patients with liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Chlamydia trachomatis in women: the more you look, the more you find

OBJECTIVE

To determine the extent to which testing of multiple sites and samples is required to define whether a woman is Chlamydia trachomatis-positive.

DESIGN

One-hundred and fifty women attending the Genitourinary Medicine clinic at St Mary's Hospital were enrolled; they had not received antichlamydial antibiotics in the previous three months, were not in a high-risk group for HIV infection, or pregnant, or using an intrauterine contraceptive device. Thirty-two women were re-examined three months after recruitment.

METHODS

An urethral specimen was Gram stained (smear) and cultured for gonococci. Another urethral specimen was taken to detect C trachomatis elementary bodies (EBs) by the MicroTrak direct fluorescent antibody (DFA) test (Syva). An endocervical swab specimen was Gram stained (smear) and cultured for gonococci. One of two other endocervical swabs was used for the DFA test and was then placed in medium which was centrifuged in a MicroCentaur at 13,000 rpm for 10 min; the deposit was examined by using the DFA test. The first 15-20 ml of voided urine (first pass urine; FPU) was also centrifuged and the deposit tested similarly.

RESULTS

Of 182 cervical smears and/or deposits tested for C trachomatis, 38 were positive; more cervical deposits (37) than smears (26) were positive and, of these, one-fifth of the deposits and one-third of the smears contained fewer than 10 elementary bodies. Of 162 paired urethral smears and FPU deposits available, one or other specimen of 36 pairs was chlamydia-positive, that is 31 smears and 32 deposits; of these, two-fifths of the smears and half of the deposits contained fewer than 10 EBs. Of 150 sets of cervical and urinary tract samples tested, 31 were chlamydia-positive at both sites, six in the cervix alone and four in the urinary tract alone. Of 139 women for whom there were valid first visit sample results, 36 (26%) were chlamydia-positive in the cervix, 34 (25%) in the urinary tract and 41 (29%) had at least one sample from either site positive. Overall, DFA tests of deposits from centrifuged cervical specimens achieved the highest sensitivity (88%) and those of cervical smears the lowest (70%).

CONCLUSIONS

Deposits from centrifuged cervical specimens were C trachomatis-positive more often than were cervical smears. Testing deposits from centrifuged urines was as successful as testing urethral smears. One-fifth (cervical deposits) to one-half (urine deposits) of specimens contained fewer than 10 EBs. The urinary tract was chlamydia-positive almost as frequently as the cervix but both sites needed to be tested to define whether a woman was chlamydia-positive.

Clara cell antigen in normal and migratory dysplastic Clara cells, and bronchioloalveolar carcinoma of Syrian hamsters induced by N-nitrosomethyl-n-heptylamine

Histogenetic features of lung tumours were studied in Syrian hamsters that had been induced with 6.8 mg N-nitrosomethyl-n-heptylamine/animal by gavage once a week for 35 weeks. At intervals from experimental week 2 until week 46, pulmonary tissues from hamsters were examined by light and electron microscopy. This report describes early hyperplastic lesions associated with terminal bronchioles and the progression of these lesions to bronchioloalveolar tumours. Using immunohistochemical and ultrastructural colloidal gold labelling techniques, hamster Clara cell antigen was found to be localized in Clara cell granules and smooth endoplasmic reticulum of normal cells, in dysplastic Clara cells migrating through basement membrane defects or from the open end of terminal bronchioles, and in hyperplastic peribronchiolar cell foci. The latter progressed to bronchioloalveolar tumours growing out along alveolar basement membranes in a characteristic lace-like, lepidic pattern. Tumours were composed of secretory (Clara), ciliated, mucous, and undifferentiated cells, as well as trapped, non-neoplastic alveolar type II cells. Hyperplastic neuroendocrine cell foci lining airways were immunoreactive for chromogranin, but these cells did not participate in the pre-neoplastic or neoplastic process. It is suggested that bronchioloalveolar carcinomas in hamsters are derived from bronchiolar secretory (Clara) cells growing along alveolar walls, differentiating into other bronchiolar cell types and entrapping resident alveolar type II cells. Due to the migratory capacity of Clara cells, it is also possible for tumours composed of bronchiolar cells to develop at the lung periphery.

Case report 815: Tear of the rotator interval

Rotator interval tears are an uncommon, but clinically important subtype of rotator cuff tear. As MRI assumes an ever increasing role in the imaging evaluation of the painful shoulder, radiologists must be aware of this entity and appreciate the difficulty in diagnosing these tears with MRI. Differentiation of a true rotator interval tear from normal synovium and capsule in this space is most likely not possible with MRI, and symptoms may be referred and misleading. It is therefore important to correlate the MR findings with the clinical history and physical examination.

Evaluation of sensitivity of 10 diagnostic assays for Chlamydia trachomatis by use of a simple laboratory procedure

AIMS

To determine the sensitivity of commercially available diagnostic assays for Chlamydia trachomatis using a simple method.

METHODS

Nine commercial assays and an "in-house" polymerase chain reaction (PCR) were evaluated using serial dilutions of a laboratory grown H serovar--four of them using a laboratory grown E serovar. Seven of the assays were further tested using dilutions of several cervical samples known to contain chlamydiae.

RESULTS

The most sensitive assays were the MicroTrak direct fluorescent antibody (DFA) test (Syva) and the PCR which detected C trachomatis at a 10(-8) dilution of the H serovar, while the two least sensitive, Clearview (Unipath) and TestPack (Abbott), were positive only at 10(-4) and 10(-3) dilutions, respectively. A range of enzyme immunoassays (EIAs) and a nucleic acid hybridisation test were of intermediate sensitivity. The results with serovar E were consistent with these. When clinical samples were examined, the DFA test detected C trachomatis in dilutions at least 10-fold greater than any other assay.

CONCLUSIONS

The range of sensitivity of diagnostic assays determined by the laboratory dilution procedure is very wide. Sensitivity assessed in this way, however, reflects the ability of the assays to detect C trachomatis in large scale clinical trials. The dilution procedure, which is simple to undertake, could therefore be applied by any laboratory before a new diagnostic method is considered for routine use.

Visualizing the distribution of elements within barley leaves by energy dispersive X-ray image maps (EDX maps)

X-ray image maps of transverse sections of barley leaf blades were compared with individual X-ray emission spectra from vacuoles of barley leaf mesophyll, epidermis and parenchymatous bundle sheath cells. Both forms of X-ray analysis revealed distinct patterns in element distribution within the leaf blade. Calcium and Cl predominated within the epidermal cell vacuoles whilst P appeared mainly in the mesophyll cell layer. Apparent accumulation of S and Mg within the bundle sheath cell vacuoles is discussed in relation to xylem unloading and sulphur assimilation.

Association of Mycoplasma genitalium with acute non-gonococcal urethritis

Chlamydia trachomatis is known to be a cause of acute non-gonococcal urethritis (NGU), though the aetiology of this disorder is not fully understood. Mycoplasma genitalium has been isolated from a few men with NGU, but culture has remained difficult and reliable detection became possible only with a specific polymerase chain reaction (PCR). We have used the PCR to examine the role of M genitalium in NGU. M genitalium was detected in urethral samples from 24 (23%) of 103 men with symptoms, signs, or both, of acute NGU, but from only 3 (6%) of 53 men without NGU (p < 0.006). This association was independent of the presence of C trachomatis and could not be explained by differences in age, ethnic, origin, lifetime number of sexual partners or a change in sexual partner during the previous 3 months. The clinical response of the mycoplasma-positive men to doxycycline treatment was at least as satisfactory as that of the chlamydia-positive men. These findings suggest that the association of M genitalium with NGU is likely to be causal, a notion consistent with the known virulence characteristics of this microorganism and its ability to cause urethritis in male sub-human primates.

Bone lead measurement using X-ray fluorescence

An in-vivo x-ray fluorescence (XRF) bone lead analyser, based on the Somervaille design, has been constructed and tested as the first step towards developing a deep bone lead analyser to expand the range of bone tissue available for assessment, to include more deep seated bones such as the femur & vertebrae. These bones represent a major component of the total body bone tissue and therefore the lead body burden. A new test analyser, constructed by modification to the basic design of a superficial bone analyser, has been used to investigate the feasibility of using changes in source-detector geometry and collimation to improve deep bone lead sensitivity for in-vivo measurement techniques. Initial results indicate that the relative detection sensitivity of the test analyser is approximately 6 times that of the Somervaille based system. The results of examination of a series of lead loaded plaster of paris phantoms (0 ppm - 360 ppm) confirmed there was good correlation (r = 0.996, p < 0.0005) between the measured ratio (lead X-rays/coherent scatter photons) and the lead concentrations using data from both XRF analyser systems.

The influence of conformity and constraint on translational forces and frictional torque in total shoulder arthroplasty

Glenoid loosening in total shoulder arthroplasty (TSA) may result from translational forces and frictional torque generated at the articular surfaces and transmitted to the fixation interface. The effect of glenohumeral articular design on the magnitude of these translational forces and frictional torques has not been evaluated previously. Seven different glenohumeral designs were evaluated on a specially designed fixture integrated with a materials test system. The degree of conformity and constraint in the glenohumeral designs directly affected the forces generated during translation and rotation of the humeral head. Maximum translational forces occurred close to the midline in the more conforming design. The less conforming designs generated lower translational forces and frictional torques. Because frictional torque and translational forces at the glenohumeral articulation may contribute to glenohumeral loosening, the use of less conforming and less constrained designs is advocated where possible to reduce the potential for mechanical loosening of the glenoid component.

Evaluation of sensitivity of 10 diagnostic assays for Chlamydia trachomatis by use of a simple laboratory procedure

AIMS

To determine the sensitivity of commercially available diagnostic assays for Chlamydia trachomatis using a simple method.

METHODS

Nine commercial assays and an "in-house" polymerase chain reaction (PCR) were evaluated using serial dilutions of a laboratory grown H serovar--four of them using a laboratory grown E serovar. Seven of the assays were further tested using dilutions of several cervical samples known to contain chlamydiae.

RESULTS

The most sensitive assays were the MicroTrak direct fluorescent antibody (DFA) test (Syva) and the PCR which detected C trachomatis at a 10(-8) dilution of the H serovar, while the two least sensitive, Clearview (Unipath) and TestPack (Abbott), were positive only at 10(-4) and-3 dilutions, respectively. A range of enzyme immunoassays (EIAs) and a nucleic acid hybridisation test were of intermediate sensitivity. The results with serovar E were consistent with these. When clinical samples were examined, the DFA test detected C trachomatis in dilutions at least 10-fold greater than any other assay.

CONCLUSIONS

The range of sensitivity of diagnostic assays determined by the laboratory dilution procedure is very wide. Sensitivity assessed in this way, however, reflects the ability of the assays to detect C trachomatis in large scale clinical trials. The dilution procedure, which is simple to undertake, could therefore be applied by any laboratory before a new diagnostic method is considered for routine use.

Improved prediction of extracellular and total body water using impedance loci generated by multiple frequency bioelectrical impedance analysis

Bioelectrical impedance analysis (BIA) using a frequency of 50 kHz is an established method of predicting total body water (TBW). However, very little research has been performed to determine whether 50 kHz is the optimum frequency for the prediction of TBW from impedance measurements. This paper analyses a mathematical expression describing the equivalent electrical circuit for biological tissue, and derives a graphical representation of the resistive and reactive components. The nature of the resulting impedance locus was used in the analysis of measured whole-body impedance of 42 rats over a range of frequencies to determine the impedance at the characteristic frequency, Zc, and also the impedance at zero frequency, R0. The standard error associated with the prediction of TBW (determined by isotope dilution) using Zc was 5.9% compared with a standard error of prediction of 10.1% using the established BIA method at 50 kHz on the same data. Predictions of extracellular water (ECW) using the impedance at zero frequency, R0, yielded a standard error of 3.2% compared with standard errors of 4.8% and 4.2% using single frequency BIA measurements at 5 kHz and 1 kHz, respectively. These results demonstrate a significant (P < 0.01) improvement in the prediction of TBW and ECW using multiple frequency bioelectrical impedance analysis (MFBIA).

Detection of Chlamydia trachomatis in men. Sensitive tests for sensitive urethras

The value of examining the centrifuged deposit from a first pass urine sample by an amplified enzyme-linked immunosorbent assay (ELISA) to detect Chlamydia trachomatis was assessed. The results were compared with those obtained by examining a urethral smear with a direct fluorescent antibody (DFA) test (MicroTrak; Syva, Palo Alto, CA). When the first pass urine sample yielded positive results for the IDEIA, but results of the DFA test of the corresponding urethral sample were negative, the remaining centrifuged deposit from the urine sample was examined by the DFA test. If results of this DFA test were positive, the IDEIA result was regarded as a true positive. Paired samples were collected by nursing staff from 190 men attending a clinic for sexually transmitted diseases (STDs). The quality of sampling thus reflected routine practice. The sensitivity of the IDEIA using first pass urine samples was 90% (37/41), and the sensitivity of the DFA test of urethral samples was 83% (34/41). The adoption of testing of first pass urine samples for the detection of C. trachomatis in STD clinics will not lead to a decrease in sensitivity for detecting C. trachomatis and will be more acceptable to patients than urethral swabbing.

A longitudinal study of pelvic inflammatory disease

OBJECTIVE

To study the microbiology and long term prognosis of pelvic inflammatory disease (PID).

DESIGN

A prospective study of women with laparoscopically confirmed PID.

SETTING

Teaching hospital in central London.

SUBJECTS

23 women with PID.

OUTCOME MEASURES

Microbiological investigations at the time of diagnosis and at follow up; subsequent fertility and the occurrence of pelvic pain.

RESULTS

PID diagnosed by laparoscopy was regarded as moderate to severe in 15 cases. Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum or a combination of these micro-organisms were detected most frequently in the cervix, less often in the endometrium and least in the tubes, C. trachomatis being the micro-organism found most commonly in the tubes. There was serological evidence of acute chlamydial infection in 13 of 20 cases in which paired sera were available and a serological response to M. hominis in 9 of 12 cases in which it was possible to evaluate the results. On the basis of microbiological and serological results, C. trachomatis appeared to be the most important aetiological agent in 10 cases, N. gonorrhoeae in four cases, M. hominis in three cases and U. urealyticum in none; in five cases, two of these micro-organisms appeared to be of equal importance. After 1 to 3 years, 33% of the women were having difficulty conceiving and 56% continued to complain of pelvic pain.

CONCLUSION

It is difficult to be certain of the infectious cause of PID in any given case. However, the evidence that N. gonorrhoeae and C. trachomatis are pathogens is very strong. M. hominis may be responsible for a few cases on its own or together with other micro-organisms.

Multi-frequency bioelectrical impedance augments the diagnosis and management of lymphoedema in post-mastectomy patients

The value of multiple frequency bioelectric impedence analysis (MFBIA) in the monitoring and management of post-mastectomy lymphoedema of the arm was evaluated in 15 patients and controls. The technique was found to produce quantitative agreement with a clinical diagnosis of lymphoedema and with the currently-used measure (limb volume calculated from circumferential measurements) of limb size. The significance of this finding lies in MFBIA being diagnostically informative: it indicates when an observed change in limb volume is directly, albeit theoretically, attributable to accumulation of extracellular fluid. MFBIA potentially offers the means for earlier definitive diagnosis and more-accurate monitoring of extracellular fluid changes during and after treatment.

Bioelectrical impedance analysis for measurement of body fluid volumes: a review

The need for a portable, inexpensive, accurate and safe method for measuring body composition is well established. Bioelectrical impedance analysis (BIA) has the potential to partially meet this need by estimating the water component of body composition. There are still a number of unresolved questions and limitations to the applications of BIA, however. This paper briefly reviews the theory of BIA, its application and its limitations. Recent progress in the development and validation of swept or multiple frequency BIA used to determine both extracellular water and total body water is discussed in detail.

Bone lead measurements in patients with chronic renal disease studied over time

Results of longitudinal studies that involved the measurement of lead by different methodologies are presented for two groups of patients with chronic renal disease. Methodologies for all patients included x-ray fluorescence measurements of finger-bone lead. These measurements were conducted 5 y apart for one group of patients (n = 15). Initial measurements for the other group (n = 15) were supplemented by bone lead levels obtained either from skull at craniotomy or from skull, and sometimes rib, at autopsy. Most subjects also underwent ethylenediaminetetraacetic acid (specifically CaNa2 EDTA) lead-mobilization testing. A correlation between rate of decrease in finger-bone lead and immunoreactive parathormone levels was suggested. Renal patients were compared with age-matched controls, and their bone half-lives did not differ. The data are discussed and related to other results obtained from clinical and nonclinical populations in which trabecular and cortical bones were studied, and our results were consistent with evidence that more rapid turnover of lead occurs in trabecular bone than in cortical bone. No support was found for the hypothesis that patients who undergo renal dialysis accumulate lead in bone.

Localization of sucrose synthase in soybean root nodules

Immunogold labelling studies using polyclonal antibodies to sucrose synthase suggest that this enzyme is exclusively located in the cytoplasm of soybean nodule cells. A significantly greater intensity of labelling was found in the cytosol of uninfected interstitial cells of the central nodule region compared with the cytosol of the infected cells. Labelling was low in the bulk of the cortical cells but was found to be high in the vascular endodermis and in the cortical cells between the bundle and the infected region. The results are discussed in relation to carbohydrate supply and metabolism and in the context of nodule structure.

Detection of Chlamydia trachomatis DNA in joints of reactive arthritis patients by polymerase chain reaction

In 1986, Chlamydia trachomatis elementary bodies were found by direct immunofluorescence (DIF) in synovial-fluid cell deposits and synovial-membrane biopsy samples from five of eight patients with sexually acquired reactive arthritis (SARA) but in none of eight controls with other types of arthritis. Cells from the original slides (stored at 4 degrees C) have now been examined by a polymerase chain reaction (PCR) that amplifies DNA for the major outer membrane protein of C trachomatis. Chlamydial DNA was found in samples from four DIF-positive patients, one DIF-negative patient, and one DIF-negative control. Overall, there was 80% concordance for DIF and PCR results. This study supports our previous finding of chlamydiae in joints in reactive arthritis.

Systemic and local carcinogenesis by directly acting N-nitroso compounds given to rats by intravesicular administration

A number of directly acting carcinogenic N-nitroso compounds were administered to female F344 rats intravesically, to assess their ability to induce tumors locally in the urinary bladder and systemically following absorption through the bladder mucosa. The compounds were alkylnitosoureas and alkylnitrosocarbamates and could be formed by interaction of amides with bacterially produced nitrite in infected bladders. Methylnitrosourethane was very toxic: doses of 1-2 mg caused death of some rats. A total dose of 0.15 mmol of ethylnitrosourethane, which was much less toxic, was administered to each rat and almost all developed bladder tumors. Ethylnitrosourea also gave rise to bladder tumors following intravesical treatment, and induced some tumors systemically, whereas methylnitrosourea, 2-methoxyethylnitrosourea and 2-hydroxypropylnitrosourea induced bladder tumors in high incidence and few tumors systemically. Nitrosooxazolidone was quite toxic and induced few bladder tumors. The dialkylnitrosoureas were more stable and some induced more tumors systemically than the monoalkylnitrosoureas. 1,3-Dimethylnitrosourea induced no bladder tumors and 1,3-diethylnitrosourea very few, but both induced tumors systemically that were similar to those induced by gavage treatment of rats. 1-Ethyl-1-nitroso-3-hydroxyethylurea, 1-hydroxyethyl-1-nitroso-3-ethylurea and 1-(2-hydroxypropyl)-1-nitroso-3-(2-chloroethyl)-urea induced bladder tumors in a majority of rats treated intravesically; the first induced many tumors systemically. Most of the bladder tumors were transitional cell papillomas and carcinomas, but there were a few squamous cell tumors, smooth muscle tumors, sarcomas and carcinosarcomas. The effects of intravesical administration of the directly acting alkylating compounds are compared with the effects of similar doses given to rats by gavage.

Repeated bone lead levels in Queensland, Australia--previously a high lead environment

Bone lead levels (finger and tibia) were measured, both in vivo and in vitro, with an x-ray fluorescence technique. In vivo finger-bone lead levels of 105 volunteers were estimated and subsequently re-estimated after a 5-y period. In many instances, elevated levels in some of these individuals probably resulted from lead ingested during childhood (i.e., more than 60 y ago). A decline in finger-bone lead from the initial value was accompanied by a mean finger-bone lead half-life of 6.2 y (n = 25); many individual's half-life values were less than 3.0 y. Perhaps one reason for these low values is the special propensity of finger bone to resorption during the involutional period, at which time there are high levels of circulating parathormone.

Nutritional support in children with end-stage liver disease: a randomized crossover trial of a branched-chain amino acid supplement

Malnutrition is common in children with end-stage liver disease (ESLD) awaiting orthotopic liver transplantation (OLT), and nutritional support is assuming an important role in preoperative management. To evaluate preoperative nutritional therapy, 19 children (median age 1.25 y) with ESLD awaiting OLT were prospectively studied. Two high-energy, isoenergetic and isonitrogenous nutritional formulations delivered nasogastrically were compared: a branched-chain amino acid (BCAA)-enriched semielemental formulation and a matched standard semielemental formation. Twelve of 19 patients completed a randomized controlled study before OLT and 10 of 19 completed a full crossover study. Improvements in weight and height occurred during the BCAA supplements, with no statistical change on the standard formulation. Significant increases in total body potassium, midupper arm circumference, and subscapular skinfold thickness occurred during the BCAA supplements, whereas no significant changes occurred during the standard formulation period. Significantly fewer albumin infusions were required during the BCAA supplement. These findings suggest that BCAA-enriched formulas have advantages over standard semielemental formulas in improving nutritional status in children with ESLD, and are deserving of wider application and study.

The nature of malnutrition in children with end-stage liver disease awaiting orthotopic liver transplantation

To evaluate malnutrition in chronic liver disease, and its relationship to nutrient deficiencies and hepatic dysfunction, 27 children with end-stage liver disease were studied. Mean protein-energy intakes were 70% of recommended daily intakes. The patients were underweight and stunted with reduced mean triceps and subscapular skinfold thicknesses and midupper arm circumference. Mean total body potassium was only 63 +/- 18% of that expected for age and sex. Deficiency of essential fatty acids (32%), and low concentrations of fat-soluble vitamins (A, 92%; E, 32%), iron (32%), zinc (42%), and selenium (13%) were common. Serum ammonia concentrations were raised in all patients, and increased methionine, tyrosine, and glutamic acid, and reduced glutamine concentrations were noted. There was no correlation between the degree of malnutrition and the degree of liver synthetic function, the degree of cholestasis, or the degree of liver injury. We suggest that potentially correctable factors in addition to liver failure (eg, inadequate absorbed intake) were important determinants of malnutrition in these patients.

The carcinogenic effect of methapyrilene combined with nitrosodiethylamine given to rats in low doses

The carcinogenic effects of combinations of methapyrilene hydrochloride (MP), nitrosodiethylamine (NDEA), and phenobarbital (PB) or partial hepatectomy (PH) were examined following sequential treatment of rats. MP is a generally non-genotoxic liver carcinogen of moderate potency, NDEA is a genotoxic liver carcinogen, PB is primarily a liver tumor promoter and PH induces cell proliferation. The dose of each carcinogen was chosen to be below that causing significant liver tumor incidence when given singly. There were 12 protocols involving groups of 28 female rats each. Short treatments with NDEA and MP were followed by 60 weeks of PB promotion or by partial hepatectomy. Each treatment was given separately or in double combination as controls. Several animals of each group were killed at intervals during the experiment for examination of toxic effects and the presence of altered hepatic foci. In only 3 of 12 groups was there a significant incidence of rats with liver neoplasms: the two groups given three treatments: NDEA, MP and PB (86% tumors) or NDEA, MP and PH (33%), and the group receiving NDEA and MP without promotion (46%). The results clearly indicated a co-carcinogenic effect between NDEA and MP. Continuous PB potentiated tumor development, while PH did not. There was no evidence of liver toxicity from any of the treatments, but clear cell foci observed in three groups at weeks 13 and 33 correlated with the later development of liver neoplasms.

Small numbers of Chlamydia trachomatis elementary bodies on slides detected by the polymerase chain reaction

A method is described in which smears on slides, which had been examined previously in a direct fluorescence antibody (DFA) test for Chlamydia trachomatis, were tested by the polymerase chain reaction (PCR). Twenty four (73%) of 33 smears which contained fewer than 10 elementary bodies when examined by the DFA test were positive by the PCR. Of the nine negative smears, seven contained only one or two elementary bodies. However, single elementary bodies were detected by the PCR in seven of the 24 positive samples. Fifteen smears were negative by both methods. The ability to detect small numbers of elementary bodies by the PCR and its specificity for negative smears indicates its potential for retrospective analysis of stored, archival smears on slides.

A reappraisal of chlamydial and nonchlamydial acute non-gonococcal urethritis

A cohort of 112 men presenting with acute non-gonococcal urethritis (NGU) was investigated for the presence of Chlamydia trachomatis. Men with 3 or more episodes of NGU in the preceding 12 months, or who had received treatment for NGU in the preceding 3 months were excluded. C. trachomatis was sought by examination of urethral smears by direct immunofluorescence, and by examination of the centrifuged deposit from a first pass urine (FPU) sample by direct immunofluorescence, IDEIA, and the polymerase chain reaction. Urethral samples from 48 men were positive for CT, and the FPU samples from an additional 7 men were positive by at least 2 assays. With such intensive investigation it is likely that those men identified as chlamydia-negative were genuinely free from the infection. The clinical history and response to treatment of those men who were chlamydia-positive were compared with those of the chlamydia-negative men. They differed in that a larger proportion of the chlamydia-positive men reported having had intercourse with more than one partner in the previous 3 months, and having had fewer previous episodes of NGU. Moreover, in contrast to some previous studies, after one week of treatment with doxycycline, a larger proportion (65%) of the chlamydia-negative men than the chlamydia-positive men (40%) was cured, although the difference was not sustained following later treatment.

British Diabetic Association's discussion paper on the role of 'diabetic' foods. Nutrition Subcommittee of the British Diabetic Association's Professional Advisory Committee

1. Most diabetic foods provide slightly, but not substantially, less energy than comparable non-diabetic products. 2. Many diabetic foods have a higher fat content than their non-diabetic equivalents. This is contrary to the requirements of the 1984 Food Labelling Regulations. 3. Many diabetic products have a relatively high content of protein. 4. In percentage terms, the greatest difference between diabetic and non-diabetic foods remains that of carbohydrate content, particularly carbohydrate other than fructose or sorbitol. On a per portion basis (for instance, per teaspoon of jam) the difference is relatively small and likely to be of minimal practical significance. 5. Diabetic foods cost between 1.5 and 4 times as much as their non-diabetic equivalents. 6. Some ordinary reduced-sugar/low calorie products are preferable to diabetic products in terms of fat and energy content and cost. 7. The promotion and widespread availability of diabetic foods tend to delude patients into believing that these products are advantageous, or even necessary. Their existence also undermines current dietary teaching by implying that people with diabetes cannot eat normal foods. 8. Diabetic foods offer no significant physiological or psychological benefits to diabetic patients and can even be counterproductive to good diabetic control. There is no longer a need for special diabetic foods in the modern dietary management of diabetes.

Heterotopic bone formation after total hip arthroplasty

Formation of heterotopic bone can cause pain and limit motion, thus ruin what would otherwise have been an excellent result after total hip arthroplasty. The cause of bone formation remains controversial, and diphosphonates have been ineffective in its prevention. Radiotherapy and nonsteroidal anti-inflammatory drugs, however, are effective preventative agents. Once the bone is formed, however, surgical excision is the only effective treatment.

Differences in skin carcinogenesis by methylnitrosourea between mice of several strains

To compare the susceptibilities of the skin of different strains of mice to the carcinogenic effect of a directly acting alkylating agent, groups of 20 mice were treated twice a week with 25 microliters of a solution of methylnitrosourea in methanol. The solution was 0.04M and was applied to the shaved back of female BALB/c, Sencar, CD-1 and Swiss mice for 25 weeks. Four groups of 20 mice of each strain were 8 weeks old at the beginning of treatment. Another four groups were 58 weeks old when treatment began. More of the BALB/c mice developed skin tumors than the other three strains, the Sencar mice somewhat less. Few CD-1 mice developed skin tumors and about one third of the Swiss mice. In all four strains, there were fewer animals with skin tumors among those begun at 58 weeks than in the young mice, but the difference was small. Survival was poor among CD-1 mice, but there was not a large difference between the strains in time of appearance of first tumor, or in average latent period of skin tumors, almost all of which were carcinomas. The Sencar mice were not outstandingly more sensitive to skin carcinogenesis by MNU, as they were to UV radiation-induced skin carcinogenesis. In a comparable study in Swiss mice neither dimethylnitrosourea nor diethylnitrosourea induced skin tumors by painting and both showed only a weak systemic carcinogenic effect in the lungs, although they are directly acting mutagens.

Local and systemic carcinogenic effects of alkylating carcinogens in rats treated by intravesicular administration

Several nitrosamines and an azoxyalkane have been administered intravesically to groups of 12 female F344 rats, twice a week for 20 or 30 weeks. Many of the nitrosamines were as efficacious in giving rise to the same tumors of internal organs as when similar doses were administered orally, showing that absorption from the bladder was as rapid as from other sites. The tumors produced included lung and kidney tumors by nitrosodimethylamine, colon and Zymbal gland tumors by azoxymethane, liver tumors by methylnitrosoethylamine (but not by nitrosodimethylamine), liver and esophagus tumors by nitrosodiethylamine, liver and lung tumors by methylnitrosamino-3-pyridylbutanone, liver tumors by nitrosomorpholine, and tumors of the esophagus by methylnitroso-n-butylamine, 2,6-dimethyl-nitrosomorpholine and methylnitrosamino-N,N-dimethylethylamine. Bladder tumors were induced by intravesicular administration of only low doses of nitrosobis-(2-oxopropyl)amine and to a lesser extent by methylnitroso-n-hexylamine and nitroso-(2-hydroxypropyl)(2-oxopropyl)amine, which all induced tumors systemically in addition. The bladder mucosa seemed to lack enzymes necessary to activate most nitrosamines to locally acting proximate carcinogens, but was quite transparent to the passage of carcinogenic nitrosamines present in the urine into the body to induce tumors in distant organs.