Effect of asbestos on the P388D1 macrophagelike cell line: preliminary ultrastructural observations

The ultrastructural effects of mineral dusts on a macrophagelike cell line (P388D1) were studied by transmission electron microscopy. The cells were found to contain virus particles which probably did not exert a cytopathic effect toward the cells. During mitosis the asbestos fibers appeared to be pushed to the periphery of the cell. The distribution of the asbestos in the P388D1 cells was similar to that seen previously in cultured peritoneal macrophages, and it was concluded that the cytotoxic effect of asbestos towards the cells was due to mechanical effects, e.g., by penetrating structures such as the nucleus or phagosomes, by preventing the ordered movement of organelles with the cell or by disrupting the cytoskeletal framework of the cell.

Factors involved in the cytotoxicity of kaolinite towards macrophages in vitro

The cytotoxicity of a high purity Cornish kaolinite toward mouse peritoneal macrophages in vitro was examined. The material was cytotoxic towards these cells, the activity could be decreased substantially by pretreating the dust with poly(2-vinylpyridine N-oxide). Pretreatment of the dusts with poly(acrylic acid) had a small effect on cytotoxicity, but combinations of the polymer treatments virtually abolished the material's biological activity towards macrophages. These studies indicated that the cytotoxicity of kaolinite is not due to its flakelike morphology.

Factors involved in the cytotoxicity of UICC amosite towards macrophages

The cytotoxicity of various ball-milled UICC amosite samples toward mouse peritoneal macrophages in vitro was examined. On increased ball milling, the cytotoxicity of the amosite samples fell. This decreased biological activity seemed to correlate best with number of fibers longer than 4 micron/micrograms dust, rather than total number of fibers or the electrophoretic mobility of the amosite samples.

Plasma vasopressin and blood pressure. Studies in normal subjects and in benign essential hypertension at rest and after postural challenge

Plasma vasopressin levels were compared in three groups comprising normotensive, mildly hypertensive, and more severely hypertensive patients, both under basal conditions and following an 85 degrees head-up tilt, a stimulus known to provoke vasopressin release in man. Vasopressin levels increased two- to fivefold in all subjects after tilt; however, neither the basal levels nor the maximal levels attained at 45 to 60 minutes after tilt differed in the three groups. These data do not support the postulated role for vasopressin in the causation or perpetuation of non-accelerated essential hypertension in man.

Investigation of hypertension

Ferguson (1975) calculated that if 5 per cent of the estimated 20 million patients with hypertension in the USA had a secondary cause, the cost of their investigation would amount to $2 billion at 1975 prices. For the majority of patients a careful clinical appraisal together with simple biochemical screening tests and a baseline ECG and chest film are adequate before embarking on therapy. For those patients in whom there are clinical or other grounds to suspect a treatable secondary cause, a wide range of modern investigative techniques are available. Even if there are no clues to a secondary cause initially, the possibility of such a cause is occasionally suggested by failure of response to triple therapy with, for example, a thiazide, a beta blocker, and a vasodilator. Whether the hypertensives are being treated in general practice or in hospital, a careful initial assessment together with regular supervision is essential to allow the identification of those with potentially curable disease.

The electrophoretic mobilities of minerals determined by laser Doppler velocimetry and their relationship with the biological effects of dusts towards macrophages

The role of surface charge in the pathogenicity of mineral dusts has been little studied, partly due to the time consuming nature of such determinations using conventional microelectrophoresis apparatus. In this work the use of laser Doppler velocimetry proved to be a rapid method of determining the electrophoretic mobility of mineral dusts. Ceramic ball milling of fibrous minerals, whilst dramatically reducing the cytotoxicity of the dusts towards macrophages, had only a small effect on electrophoretic mobility. It is concluded that some other factor, possibly fibre morphology, is important for observed biological effects. The coating of quartz and kaolinite with poly-2-vinyl pyridine-N-oxide dramatically lowered their cytotoxicity towards macrophages. The dusts' electrophoretic mobilities were also lowered. The significance of these findings is discussed.

Cytotoxicity of talc for macrophages in vitro

The cytotoxicity of seven specimens of respirable talc dust for mouse peritoneal macrophages in vitro was studied. All talcs showed modest but consistent macrophage cytotoxicity and would be expected to be fibrogenic in vivo. Available data suggest that under certain circumstances respirable talc can cause lung fibrosis in animal inhalation studies. As most of the talc specimens under investigation were of high purity it seemed unlikely that the cytotoxicity was due to the presence of small quantities of contaminating minerals.

Improvement in cardiac performance by oral long-acting theophylline in chronic obstructive pulmonary disease

Although oral theophylline is a widely used bronchodilator in chronic obstructive pulmonary disease (COPD), its effects upon cardiac performance have not been fully established. The effect of slow release oral theophylline upon right ventricular and left ventricular ejection fraction was evaluated using first-pass quantitative radionuclide angiocardiography in 15 patients with COPD. After 72 hours of therapy, oral theophylline significantly increased right ventricular ejection fraction (42% to 48%, p less than 0.005). In 7 of 10 patients with depressed baseline right ventricular performance, including two with cor pulmonale, right ventricular ejection fraction normalized (greater than or equal to 45%). After long-term therapy, an average of 16 weeks, right ventricular fraction also increased (43% to 48%, p less than 0.005). Left ventricular ejection fraction improved significantly from 64% to 68% (p less than 0.05) at 72 hours and from 61% to 65% (p less than 0.025) after long-term therapy. These data indicate that oral theophylline produces a sustained modest enhancement of resting biventricular performance in COPD.

Rebreathing in a subject wearing an integral crash helmet

The respired air of a volunteer was analysed while he was wearing a variety of integral crash helmets. Observations were made with and without a protective balaclava, bib or scarf, or both. Rebreathing occurred and the peak inspired oxygen tension fell as low as 16.0 kPa (120 mm Hg) with a minimum inspired carbon dioxide of 2.1 KPa (16.0 mm Hg). Accessories worn or attached to the helmet which restrict airflow into the helmet should not be used. Attention should be paid to the "air conditioning" of helmets when worn with flameproof balaclavas and bibs.

Alterations in heart rate and rhythm at urography with sodium diatrizoate

One hundred and thirty-five consecutive patients referred for urography were monitored electrocardiographically before, during and after injection of 60 ml Hypaque 45% (sodium diatrizoate 45% w/v) over 60 seconds. The injection produced a significant increase in heart rate, while venepuncture alone had no such effect. Twenty-nine (21%) patients developed minor arrhythmias and 6 (4.4%) major arrhythmias following the injection. Major arrhythmias occurred in the older age groups and were more frequent in males. An abnormal baseline rhythm strip had significant predictive value in determining the development of further arrhythmias.

Biological effects of tremolite

Tremolite is an amphibole which has been implicated in a variety of disease patterns in different parts of the world. It occurs in a number of phases, which are chemically identical but have specific physical characteristics. In an attempt to clarify the epidemiological findings, tremolite fibres of 3 specific forms--A, B and C--were characterized and studied for biological activity by: (i) in vivo intrapleural injection of rats (2 separate experiments--1 with poor survival). (ii) in vitro enzyme release from mouse peritoneal macrophages (iii) in vitro giant-cell formation in A549 cultures (iv) in vitro cytotoxicity for V79-4 cells. Sample C, which contained more long thin fibres than A and B, was alone in producing mesotheliomas. C, but not A or B, induced LDH and B-glucuronidase enzyme release, and induced giant cells. A was not cytotoxic, B moderately cytotoxic and C as highly cytotoxic as UICC crocidolite. The in vivo studies were marred by being split between 2 experiments, of which the second had poor survival. We are aware of the weakness of our in vivo data, but as Tremolite C was being considered for commercial use on the European market we felt it timely to submit our findings for publication.

An ultrastructural study of the effects of asbestos fibres on cultured peritoneal macrophages

The effects of crocidolite and chrysotile fibres on lavaged peritoneal macrophages have been studied by both scanning (SEM) and transmission (TEM) electron microscopy. SEM provided little information (as the surface topography did not reflect the underlying cytoplasmic organization) except that it showed that individual macrophages often partially engulfed many long fibres in a random fashion. TEM revealed the fibres in and protruding from membrane-bound vacuoles, free in the cytoplasm and penetrating the nucleus. The cellular distribution of the fibres is discussed in terms of the cytotoxic nature of the fibres and their ability to produce a selective release of enzymes from the macrophages.

Present use of five-day wards

A survey of five-day wards serving medical and surgical specialties indicated that 30 such units were operating in England in 1979. Six mixed surgical specialty, eight mixed specialty (medicine and surgery), four medical investigation, and 12 single specialty wards had opened since 1969. There was a varied, and often low, use of these wards. Nurse-staffing levels and allocation of operating theatre time also varied considerably. In busy wards nurse-staffing levels were high and access to operating theatre time reasonable. Medical investigation wards showed some of the highest levels of occupancy and throughput. The potential savings and service improvements that can result from five-day wards have yet to be realised on a wide scale.

Surface topography of the female bladder trigone

Cystoscopic biopsy specimens of the bladder trigone of young women with recurrent urinary infections were examined by scanning electron microscopy. The superficial cells of the thickened squamous epithelium of the trigone have either a microridged, microvillous, or mixed pattern. In one case, bacteria were found adherent to all these types of surface. Some cells have a microvillous surface and a cobblestone pattern with long, clubbed microvilli and resemble the cells found in malignant and premalignant states.

Atropine--a safe drug

Three children received 1000 times the prescribed dose of atropine sulphate and recovered from the main effects of excitatory behaviour and hallucinations in 48 hours. Diazepam was effective in the control of this behaviour. It is suggested that physostigmine should be available where atropine and hyoscine are used or where overdoses are managed.

Silica-induced malignant histiocytic lymphoma: incidence linked with strain of rat and type of silica

It has already been established that a single intrapleural inoculation of crystalline silica (quartz) produces malignant lymphomas of histiocytic type (MLHT) in Wistar-derived rats. It has now been shown that after treatment with Min-U-Sil, rats of the Alderley Park strain have a tumour incidence of 35%, whereas the incidence in Agus rats is 5% and in PVG 8%. There was also a significant difference in the incidence of MLHT caused by injecting different samples of crystalline silica, particularly of tridymite. There was correlation between cytotoxicity to mouse peritoneal macrophages and tumour incidence, except for one dust (DQ12). Zeta potential, number of particles and their size range were considered, but the incidence does not show a clear correlation with these measurements. The results are discussed.

Conversion of triglycylvasopressin to lysine-vasopressin in man

The concentrations in plasma of triglycl-8-lysine-vasopressin (TGLVP), determined by radioimmunoassay, and lysine-vasopressin, determined by bioassay, have been monitored in five subjects after intravenous (7.5 micron/kg) or intranasal (5 mg) administration of TGLVP. The level of excretion in urine was also measured. The TGLVP concentration in plasma fell rapidly after the intravenous injection, the mean half-time of disappearance being 24.2 +/- 1.9 (S.E.M.) min (d.f. 4). Biologically active lysine-vasopressin reached a peak between 60 and 120 min. A similar pattern was seen following intranasal instillation but only a small proportion of the administered dose appeared in the plasma and the concentration of lysine-vasopressin was relatively higher. Less than 1% of the TGLVP injected appeared in the urine. Intravenous TGLVP had no effect on systolic blood pressure but produced an increase in diastolic blood pressure of 1.7 +/- 0.19 kPa (d.f. 4) and a fall in heart rate of 9 +/- 2.3 beats/min. Creatinine clearance and sodium excretion remained relatively constant in all subjects throughout the study but intravenous injection of TGLVP resulted in an antidiuresis which was evident within the first hour of observation and was maintained for a further 4 h. It was concluded that TGLVP is converted to lysine-vasopressin in man and after an intravenous injection of 7.5 micron/kg sufficiently high concentrations of lysine-vasopressin may be maintained for 2 h to produce sustained vasoconstriction. Tryglycylvasopressin may therefore be of value in controlling haemorrhage.

Municipal waterborne giardiasis: an epidemilogic investigation. Beavers implicated as a possible reservoir

In March 1976, 128 persons in Camas, Washington, had laboratory-confirmed giardiasis. A questionnaire survey of 498 Camas residents revealed that 3.8% had clinical giardiasis, while none of 318 residents in a control town were ill. No associations between illness and sex, pet ownership, travel, time spent in wilderness areas, public gatherings, or food preference were found. Giardia cysts were recovered from raw water entering the city water treatment system via two streams and also from two storage reservoirs containing chlorinated and filtered stream water. Failure to remove Giardia cysts was attributed to the water plants' inadequate flocculation, coagulation, and sedimentation combined with deterioration of the filter media. Investigation of the watershed revealed no signs of human fecal contamination. Animal trapping in the watershed area yielded three beavers (Castor canadensis) infected with Giardia that were infective for specific pathogen-free beagle pups.

Fast azimuthally dependent model of the reflection of solar radiation by plane-parallel clouds

A fast analytical model of the transfer of solar radiation in plane-parallel clouds is developed by extending the Eddington approximation to handle an azimuthally dependent radiance field. When compared with the more precise doubling method, the results from this approximate model show a typical accuracy of better than 3% for fluxes and 10% for intensities over a wide range of input parameters. This accuracy may deteriorate somewhat for small cloud thicknesses, large solar zenith angles, viewing angles close to the horizon, or viewing angles close to the solar azimuthal direction. The computational speed of the analytical model is, however, a few hundred times faster than that of the more precise models, which makes it well suited for applications involving iteration over spectral intervals, time intervals, or cloud populations.