Per- and Polyfluoroalkyl Substances (PFAS) in mixtures show additive effects on transcriptomic points of departure in human liver spheroids

Per- and polyfluoroalkyl substances (PFAS) are a wide range of chemicals that are used in a variety of consumer and industrial products leading to direct human exposure. Many PFAS are chemically non-reactive and persistent in the environment, resulting in additional exposure from water, soil, and dietary intake. While some PFAS have documented negative health effects, data on simultaneous exposures to multiple PFAS (PFAS mixtures) are inadequate for making informed decisions for risk assessment. The current study leverages data from previous work in our group using Templated Oligo-Sequencing (TempO-Seq™) for high-throughput transcriptomic analysis of PFAS-exposed primary human liver cell spheroids; herein, we determine the transcriptomic potency of PFAS in mixtures. Gene expression data from single PFAS and mixture exposures of liver cell spheroids were subject to benchmark concentration (BMC) analysis. We used the 25th lowest gene BMC as the point of departure to compare the potencies of single PFAS to PFAS mixtures of varying complexity and composition. Specifically, the empirical potency of eight PFAS mixtures were compared to predicted mixture potencies calculated using the principal of concentration addition (i.e., dose addition) in which mixture component potencies are summed by proportion to predict mixture potency. In this study, for most mixtures, empirical mixture potencies were comparable to potencies calculated through concentration addition. This work supports that the effects of PFAS mixtures on gene expression largely follow the concentration addition predicted response and suggests that effects of these individual PFAS in mixtures are not strongly synergistic or antagonistic.

Cardiac muscle tissue engineering: toward an in vitro model for electrophysiological studies

The objective of this study was to establish a three-dimensional (3-D) in vitro model system of cardiac muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched cardiac muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50-70 micrometer thick) in which differentiated cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological properties of enriched constructs were superior to those of regular constructs but inferior to those of native ventricles. These results demonstrate that 3-D cardiac muscle constructs can be engineered with cardiac-specific structural and electrophysiological properties and used for in vitro impulse propagation studies.

An interactive workshop: An effective means of integrating the Canadian Cardiovascular Society clinical practice guidelines on congestive heart failure into Canadian family physicians' practice

OBJECTIVE

To use an interactive workship as a means of integrating clinical practice guidelines on congestive heart failure into Canadian family physicians' practice.

SETTING

Interested practitioners from the Association des Médecins Omnipraticiens de Québec, the Centre de Santé Publique de Québec and the continuing medical education (CME) department, Merck Frosst Canada, Montreal, formed the initial task force. Train-the-trainer sessions took place in many provinces in a variety of CME settings.

DESIGN

The interactive, problem-based workshop was facilitated by local interested general practitioners, while local experts served as consultants to reinforce key messages from clinical practice guidelines and to guide participants through the learning process.

MAIN RESULTS

By December 31, 1996, 187 family practitioners and 81 specialists had been trained in train-the-trainer sessions across the country. A total of 1698 general practitioners had participated in over 52 workshops during the same time. Pre- and postworkshop testing indicate that the workshops improved knowledge, and that the knowledge gained during the workshop was retained at three- and six-months' follow-up. Separate chart evaluations conducted before and after the workshop showed that participants provided more complete chart information related to congestive heart failure and that they significantly increased their use of angiotensin-converting enzyme inhibitor therapy after the workshop. Participant evaluation of the workshop also indicates a high index of satisfaction with the presentation and the content of the workshop as being relevant to clinical practice.

CONCLUSION

An interactive, problem-based, small group workshop developed by a core group of interested practitioners and guided by local trained facilitators and experts is an effective teaching tool through which clinical practice guidelines can be successfully transferred into clinical practice in a timely and meaningful way.

Lower extremity: nonstepping digital angiography with photostimulable imaging plates versus conventional angiography

PURPOSE

To compare nonstepping digital subtraction angiography (DSA) (ie, storage phosphor radiography adapted to a stationary imaging plate changer) with conventional screen-film angiography in the evaluation of the lower extremities.

MATERIALS AND METHODS

Fifty-one patients with peripheral vascular disease underwent both nonstepping DSA and screen-film angiography. The angiographic and radiologic techniques of both systems were kept identical for each patient. Three radiologists independently rated the overall quality of each angiogram. In their evaluations for each of 12 arterial segments on all 102 angiograms, they also rated the degree of opacification, the diameter reduction of the most severe stenosis, and their level of confidence.

RESULTS

Mean overall quality scores and levels of confidence were better for nonstepping DSA than for screen-film angiography (P < .001). Full opacification was reported in 95.6% and 89.2% of all 1,836 segments with nonstepping DSA and screen-film angiography, respectively (P < .0001). The difference between the mean stenosis grades obtained with screen-film angiography and nonstepping DSA was not statistically significant. Intertechnique agreements were good (kappa = 0.77, 0.81, and 0.81), whereas interobserver agreements were influenced by the observer's experience with the imaging techniques.

CONCLUSION

Nonstepping DSA images of the lower extremity were of better diagnostic quality than were screen-film angiograms. The development of dedicated nonstepping DSA equipment is warranted.

Pilot study on the contamination of drinking water by organotin compounds from PVC materials

Raw and treated water samples and tap water samples from four to six houses located on distribution lines where PVC pipe/tubing had been recently installed were collected in five Canadian municipalities for the analysis of organotin compounds. After derivatisation with sodium tetraethylborate the ethylated organotin compounds were extracted with hexane and analysed by gas chromatography-microwave induced plasma atomic emission spectrometry using a wavelength (326.234 nm) specific for tin. Organotin compounds, mainly methyltin and dimethyltin at concentrations ranging respectively from 0.5 to 257 ng Sn/L and from 0.5 to 6.5 ng Sn/L, were detected in samples from ten of the twenty-two houses. No organotin compounds were detected in raw water or treated water leaving the treatment plant, indicating that the organotin compounds were leaching into the water from some component of the distribution system.

Comparison of two administration techniques of inhaled nitric oxide on nitrogen dioxide production

The purpose of this study was to verify whether, compared with the introduction of the NO-N2 mixture at the air inlet of the ventilator (classical method), a direct injection of NO-N2 into the inspiratory line of the ventilator circuit with a new injection device (new method), would reduce NO2 formation by reducing contact time between O2 and NO. The effect of two FIO2(0.21 and 0.90) and NO concentrations on NO2 production was determined. In the classical method, NO and O2 were mixed with an air/oxygen blender before the gas mixture entered the ventilator. In the new method, NO was injected directly into the respiratory line with the injection system. Nitric oxide and nitrogen dioxide gases were measured using a chemiluminescence analyzer. For a FI02 of 0.90 and 90 ppm of NO2, the amount of NO2 produced was decreased from 8.9 +/- 0.8 ppm (mean +/- SD) with the classical injection system to 4.4 +/- 0.2 ppm with the new injection system (P = 0.0039, Mann-Whitney test), and NO2 production was decreased from 4.5 +/-0.2 ppm to 2.1 +/- 0.4 ppm (P = 0.02) at 60 ppm of NO. However, at a FIO2, no difference was found in the amount of NO2 produced. We conclude that, compared with the classical method of NO administration, the new NO injection system reduces considerably the concentration of inhaled NO2 when a high FIO2 and a high concentration of NO are used.

Radiation doses to patients in neurointerventional procedures

PURPOSE

To evaluate stochastic and deterministic risks associated with neurointerventional procedures for the patient.

METHODS

Eight neurovascular interventional procedures were evaluated to determine the entrance skin dose and effective dose for the patient. Dosimetry was done with thermoluminescence dosimeters. The highest dose on the patient's head was recorded as the maximum entrance skin dose. The equivalent dose was obtained by conversion of the dose-area product using published conversion tables.

RESULTS

The maximum entrance skin dose varied from 129 to 1335 mGy. The mean effective dose was 1.67 mSv with a range of 0.44 to 3.44 mSv. No deterministic effect has been encountered. Stochastic risk linked to the highest effective dose value was approximately one death by fatal cancer for every 6000 procedures, according to the new International Commission on Radiological Protection coefficient.

CONCLUSIONS

Because no deterministic effect has been detected, and stochastic risks were very low, radiation hazard to the patient is a minor consideration in deciding whether to undertake a neurointerventional procedure.

Analogous filters for beam shaping in diagnostic radiology

A computer simulation based on photon transport calculation was used to evaluate the properties of a wide variety of materials that could be used for the filtration of x-ray beams. A single filter was added to the inherent filtration. For comparison, the concept of analogous filters was introduced: two filters were considered analogous if both produced the same ratio of entrance exposure at the patient to the energy absorbed in the detector consisting of a pair of intensifying screens positioned immediately behind the water phantom. The efficiency, contrast and integral dose were calculated for filters of odd atomic numbers from 1 to 91 with a large number of different parameters (48,600 different combinations). They include essentially all major diagnostic radiology procedures, except mammography. Only extreme cases are presented here. No magic filter was found which would produce increased contrasts or a decreased integral dose, while maintaining efficiency close to that of aluminium. Filters of some atomic numbers produced increased contrast, but had negligible efficiency. Analogous filters of atomic numbers between 7 and 37 and also between 71 and 91, had almost identical properties but varied efficiencies. Unpredictable behaviour was obtained with filters of atomic numbers 38 to 70, where small changes in atomic number may produce large changes in all the properties due to the presence of K-edge discontinuities.

The Functional Autonomy Measurement System (SMAF): description and validation of an instrument for the measurement of handicaps

The Functional Autonomy Measurement System (SMAF) is an instrument developed for the measurement of the needs of the elderly and the handicapped. Its elaboration was based on the World Health Organization's classification of impairments, disabilities and handicaps. A functional autonomy rating scale, using a four-level measurement scale, quantifies a subject's performance on 29 functions in five sectors of activity: activities of daily living, mobility, communication, mental functions and instrumental activities of daily living. For each function, the evaluator must also estimate available resources to compensate for any identified disability in order to estimate the handicap. The disability and handicap profile obtained is the basis for the prescription of home care or the allocation of chronic care beds. An inter-observer study concluded that the scale is reliable for evaluators from different professions in the community as well as in institutional settings. The instrument is rapid to administer (on average 42 min) and the reliability is not influenced by training. A study of concurrent validity has shown a strong correlation between the disability index obtained by the SMAF and the amount of required nursing-care time. This instrument can be used for clinical purposes and in epidemiological and evaluative research.

Phantom equivalent thicknesses in diagnostic radiology

Some measurements in diagnostic radiology must be done with phantoms. The most frequently used phantoms are water, plexiglass, aluminium and copper. It is interesting to know the equivalent thicknesses between these phantoms in order to be able to relate these values to real anatomical organs of known thicknesses. The use of antiscatter grids, the choice of intensifier screens, the beam size and in general the scattering parameters considerably change the equivalent thicknesses. Many situations have been simulated by the Monte Carlo method and equivalent thicknesses are presented.

Quality-control scheme for blood glucose measured outside the laboratory

We propose a quality-control (QC) scheme to evaluate the performance of blood glucose estimates made with a reflectometer in hospital wards or at home. We constructed a chart illustrating the comparison by regression analysis of the results of 254 reflectometer readings (y) and simultaneous capillary blood glucose analyses in the laboratory (x). Arbitrary acceptance limits around the regression line (y = 0.5 + 0.87x; r = 0.97, Sy/x = 0.8 mmol/L) were established, based on the mean +/- 2 SD of the reflectometer readings of a series of classes of 1.1 mmol/L interval, made with the results from the laboratory analyzer. Each ward using a reflectometer is provided with the QC chart, and the first blood glucose estimation with the reflectometer on each working shift is controlled by re-assay in the laboratory. If the reflectometer reading is outside the limits, the next glucose estimation is also re-assayed. If two consecutive readings are outside the limits, the reflectometer procedure is considered to be failing, the instrument's readings are not used for medical decisions, and remedial action is taken. The chart can also be used as a teaching tool for training the patients or the nurses and to evaluate individual performance.

Quality-control scheme for blood glucose measured outside the laboratory

We propose a quality-control (QC) scheme to evaluate the performance of blood glucose estimates made with a reflectometer in hospital wards or at home. We constructed a chart illustrating the comparison by regression analysis of the results of 254 reflectometer readings (y) and simultaneous capillary blood glucose analyses in the laboratory (x). Arbitrary acceptance limits around the regression line (y = 0.5 + 0.87x; r = 0.97, Sy/x = 0.8 mmol/L) were established, based on the mean +/- 2 SD of the reflectometer readings of a series of classes of 1.1 mmol/L interval, made with the results from the laboratory analyzer. Each ward using a reflectometer is provided with the QC chart, and the first blood glucose estimation with the reflectometer on each working shift is controlled by re-assay in the laboratory. If the reflectometer reading is outside the limits, the next glucose estimation is also re-assayed. If two consecutive readings are outside the limits, the reflectometer procedure is considered to be failing, the instrument's readings are not used for medical decisions, and remedial action is taken. The chart can also be used as a teaching tool for training the patients or the nurses and to evaluate individual performance.

Studies on L-640,035: a novel antagonist of contractile prostanoids in the lung

The effects of L-640,035 (3-hydroxymethyl-dibenzo [b,f] thiepin-5,5-dioxide) have been studied on pulmonary smooth muscle contraction in vitro and in vivo. When studied in vitro on guinea-pig tracheal chains, L-640,035 produced significant shifts in the dose-response curves to a prostaglandin (PG) endoperoxide analogue (U-44069) (pA2 7.0), PGF2 alpha (pA2 5.9) and PGD2 (pA2 6.5). L-640,035 produced no significant shift in the dose-response curves to leukotriene D4 or histamine and produced a small but statistically significant shift in the dose-response curve to 5-hydroxytryptamine (5-HT) (pA2 5.2). With the exception of PGF2 alpha, Schild analysis did not in general indicate competitive inhibition. The main metabolite of L-640,035, L-636,499, also produced significant parallel shifts in the dose-response curves to U-44069 (pA2 6.0) and PGF2 alpha (pA2 6.0), but with some reduction in the maximal contraction. When L-640,035 was administered intravenously to guinea-pigs, significant inhibition of increases in pulmonary resistance or insufflation pressure induced by U-44069 (ED50 0.16 mg kg-1), leukotriene D4 (ED50 0.25 mg kg-1) and 5-HT (ED50 3.4 mg kg-1) but not histamine (ED50 greater than 10 mg kg-1) was observed. When L-640,035 was administered intravenously to dogs a significant inhibition of increases in pulmonary resistance induced by U-44069 (ED50 0.85 mg kg-1) but not histamine (ED50 greater than 30 mg kg-1) was observed. 5 When L-640,035 was administered by the intraduodenal route to dogs at doses of 3 and 10 mg kg- significant inhibition of increases in pulmonary resistance induced by sodium arachidonate (3 mgkg1 i.v.) was observed with a duration of action of > 255 min. 6 It is concluded that L-640,035 is a novel, relatively selective, and orally active antagonist of the actions of contractile prostanoids on pulmonary smooth muscle.

Guidelines for detection of breast cancer: an update on investigative methods. A report of the ad hoc committee on mammography of The Canadian Association of Radiologists

The high incidence of breast cancer and its mortality make it imperative that women over 25 years of age have a clinical examination of their breasts at least every three years up to age 40 and annually thereafter. Before the age of 25, mammography is seldom indicated and then it should usually be limited to a spot film of a potential lesion. After 25, mammography is indicated for any woman with breast symptoms, women with metastases from cancer of an unknown primary site, and before any breast surgery. Women with a strong family history and those with large breasts should also have a mammogram between the ages of 25 and 35. Between the ages of 35 and 39 we recommend a baseline mammogram for asymptomatic women. After 39 and up to age 50, women should consult their physicians yearly to determine if, and how often, mammography should be performed. Finally, after age 50, annual mammography is suggested. In each of the above contexts, the radiologic examination should be coupled with clinical palpation of the breasts. A trained and experienced mammographer should recommend biopsy when mammograms show a typical spiculated mass; an ill-defined or even well defined mass that cannot be said to be benign; a suspicious distortion of local architecture; or a cluster of suspicious microcalcifications. Any cyst the nature of which is uncertain after puncture, or abnormal ducts on a galactogram also should make a biopsy mandatory. On the other hand, a normal mammogram should not prevent biopsy of a lesion of the nipple or of a lump detected clinically.(ABSTRACT TRUNCATED AT 250 WORDS)

Reference values for the oral glucose tolerance test at each trimester of pregnancy

A 100-gram oral glucose tolerance test (OGTT) was performed on a selected group of normal women at each trimester of pregnancy to establish reference values for hyperglycemia and hypoglycemia. Ninety three OGTT were performed in the first trimester, 121 in the second trimester, and 98 in the last trimester. The fasting serum glucose did not differ significantly between the trimesters. The values at 60 and 120 minutes were significantly different for the fifth, fiftieth, and ninety-fifth percentiles between each trimester of pregnancy. For the 180-minute readings, the fifth and fiftieth percentiles were not significantly different between the first and second trimester of pregnancy, but the results of the third trimester were significantly higher than those of the other trimesters. The mean fasting insulinemia remained relatively constant during pregnancy. Insulin response to OGTT increased during the progression of the pregnancy. The interpretation of the glucose tolerance tests during pregnancy, either to detect gestational diabetes or hypoglycemia, should take these physiologic changes into account.

[Exposure rates in fluoroscopy in Quebec]

For the past two years, the authors have measured by means of an ionization chamber the exposure rates of 155 fluoroscopic systems. Of these, 42% measured beyond the maximum of 5 R/min recommended by radiation protection codes. Systems linked to a television chain functioned at generally lower levels. There was no significant difference between remote controlled and non remote systems. However, appreciable differences between the units of two manufacturers were observed. The corrective measures which must follow this survey will result for Quebec in a saving of 2.0 millions of rads to the population which becomes, without doubt, the single most important factor of radiation protection.

Analytic clinical chemistry precision and medical needs. The Canadian Interlab Program (CIP)

Precision obtained with two different serum pools used daily as internal quality-control specimens by 130 laboratories throughout Canada (Canadian Interlab Program) is reported for 14 analytes assayed by either manual or automated methods over a period of 16 months. Precision criteria set by Barnett to meet medical needs were not met for calcium, glucose, phosphorus, and urea nitrogen by more than 10% of the laboratories studied. Specific guidelines for laboratory precision are suggested for optimal and minimal performance in the assays of albumin, bilirubin, calcium, chloride, cholesterol, creatinine, glucose, phosphorus, potassium, sodium, total protein, triglyceride, urea nitrogen, and uric acid.

CYTOPLASMIC INHIBITOR OF DEOXYRIBONUCLEASE I FROM RAT LIVER TISSUE

A cytoplasmic inhibitor has been found effective against the mitochondrial deoxyribonuclease I from rat liver tissue. This inhibitor is similar in properties to most DNAase inhibitors reported so far in the literature. Attempts at identification have led to the conclusion that this inhibitor is a β-globulin. It is a non competitive inhibitor.