In vitro dermal absorption of flame retardant chemicals.

Flame retardant chemicals may be used in furniture fabric in the future to reduce the flammability of the fabric. As a part of the process to evaluate the potential for exposure to these chemicals, this study examined the in vitro dermal absorption of two flame retardant chemicals. The chemicals were [14C]decabromodiphenyl oxide (DBDPO) and [14C]tris-(1,3-dichloro-2-propyl)phosphate (TDCP). Skin from the adult hairless female mouse (SKH1) was removed and mounted in flow-through diffusion cells. The chemicals, at three dose levels (DBDPO: 6, 30 and 60 nmol; TDCP: 20, 100 and 200 pmol), were applied in a volatile vehicle (tetrahydrofuran for DBDPO; acetone for TDCP) to the skin. Fractions of receptor fluid, pumped below the skin, were collected over a 24-h period. The skin was washed with solvent (tetrahydrofuran for DBDPO; ethanol for TDCP) to remove unabsorbed chemical 24 h after application. The receptor fluid, skin wash and skin were analyzed for chemical-derived radioactivity. The skin from the high-dose group of both chemicals, and the receptor fluid from TDCP high-dose samples, were analyzed for parent compound and metabolites by HPLC. The 24-h cumulative percent of the dose of DBDPO in the receptor fluid was very low (0.07-0.34%). The applied dose of DBDPO detected in the skin ranged from 2 to 20%. The lowest dose of DBDPO had the highest percentage of the dose (20%) in the skin. The major portion of the applied dose was removed by washing the skin 24 h after application of DBDPO, and ranged from 77 to 92%. HPLC analysis of homogenate extract prepared from the high-dose of DBDPO-treated skin showed the presence of DBDPO and a minor unknown peak. TDCP was readily detected in the receptor fluid; 39-57% of the applied dose of TDCP was in the receptor fluid by 24 h. The solvent wash removed 11-25% of the dose from the skin and 28-35% remained in it. HPLC analysis of the skin homogenate extract and receptor fluid extract from the TDCP high-dose treated samples showed the presence of parent compound and a minor unknown peak. TDCP more readily penetrated hairless mouse skin and diffused into the receptor fluid than DBDPO. TDCP has a lower molecular weight and log octanol:water partition coefficient than DBDPO. The differences in the physico-chemical properties of these two chemicals most likely explains their dissimilar absorption through hairless mouse skin.

Strain-dependent disposition of inorganic arsenic in the mouse.

Recent studies have suggested that polymorphisms in the methylation of inorganic arsenic (iAs) exist in animals and humans. Methylation of iAs is an important step in the elimination of arsenic. The objective of this study was to examine whether there are differences in iAs disposition, and hence methylation, between three strains of mice. Ninety-day-old female mice (strains: C3H/HeNCrlBR, C57BL/6NCrlBR, and B6C3F1/CrlBR) were administered [73As]arsenate or [73As]arsenite orally at dose levels of 0.5 or 5.0 mg As/kg. Another group of mice were administered [73As]arsenate (5.0 mg As/kg) intraperitoneally (i.p.). Disposition of [73As] was assessed by whole-body counting, and analysis of urine, feces and tissues for radioactivity. Urine was analyzed by chromatography for arsenic metabolites. Several strain- and dose-related effects in the disposition of [73As] were observed with both arsenicals. After oral administration, the clearance of [73As]arsenate, measured by whole-body counting, was dependent on the strain. However, because there was no strain dependence on clearance of [73As]arsenate administered i.p., the effect after oral administration may be due to a difference in absorption of arsenate between the strains. With increased oral dose of arsenate and arsenite, the clearance of [73As] was slower and there was higher tissue retention of [73As]. The percentage of metabolites excreted in urine also was affected by the administered dose. With increased dose, the percentage of arsenite and monomethylarsonic acid were significantly increased, and dimethylarsinic acid decreased. However, our results suggest there is no overall difference between these strains of mice with respect to disposition of iAs. A better understanding of the role of phenotype in the disposition and toxicity of iAs would reduce the uncertainty in arsenic risk assessment.

In vitro percutaneous absorption of dimethylarsinic acid in mice.

The objective of this study was to investigate the in vitro dermal absorption of [14C]dimethylarsinic acid. This organic arsenical is used as a herbicide and is a product of the mammalian metabolism of inorganic arsenic. Discs of preclipped dorsal skin were cut from adult female B6C3F1 mice and mounted in flow-through diffusion cells. HEPES-buffered Hanks balanced salt solution was used as receptor fluid. Doses of dimethylarsinic acid included 10, 100, and 500 micrograms and were applied onto the skin (0.64 cm2). Experiments (24 h) were conducted using solid compound and aqueous solution (20, 100, and 250 microliters) and soil (23 mg/cm2) as vehicles. The epidermal surface was washed at 24 h to remove compound that did not penetrate. The wash contained the greatest percentage of the dose in all experiments. Absorption of the compound into the skin and receptor fluid was observed and ranged from < 1 to 40% of the dose in experiments with the three exposure scenarios. The rank order of the various exposure conditions of dimethylarsinic acid absorption (10 micrograms) into the skin and receptor fluid was 20 microliters water > 100 microliters water > solid > 250 microliters water > soil. No dose or pH effects on absorption of dimethylarsinic acid was observed. There was also no pH effect on the partitioning of dimethylarsinic acid between 1-octanol and buffer. Short-term (1 h) exposure of dimethylarsinic acid in water followed by wash of the skin resulted in < 1% of the dose being absorbed. Thus, vehicles and duration of exposure have important roles on the in vitro dermal absorption of dimethylarsinic acid in mouse skin.

Dermal absorption of chemicals: effect of application of chemicals as a solid, aqueous paste, suspension, or in volatile vehicle.

The purpose of this study was to investigate the dermal absorption of chemicals in different physical forms when applied to female F344 rats. Chemicals were applied either as a solid, aqueous paste, suspension, or dissolved in the volatile vehicle ethanol. The chemicals investigated were [14C]-2-sec-butyl-4,6-dinitrophenol (DNBP, 4.2 mumol), 2,4,5,2',4',5'-[14C]-hexachlorobiphenyl (HCB, 2.3 mumol), and 3,4,3',4'-[14C]-tetrachlorobiphenyl (TCB, 0.5 mumol). The chemicals were applied on the clipped mid-dorsal region of the rat over a 2.54-cm2 treatment area, which was then occluded. Urine and feces were collected and assayed for radioactivity. Twenty-four hours post-application, the treated skin was washed with a mixture (1:1) of soap and water, dried, and reoccluded. The animals were sacrificed at 120 h by exsanguination under ether anesthesia. Radioactivity in the blood, skin (treated and untreated), and carcass was assayed. Dermal absorption of DNBP-derived radioactivity was approximately 50% of the recovered dose after application in the four physical forms, and the major route of excretion was via the urine. Twelve percent of the absorbed dose of DNBP was retained in the body. Dermal penetration of HCB-derived radioactivity was 5-8% of the recovered dose after application in the four forms, and the major route of excretion was via the feces. Greater than 90% of the absorbed dose of HCB-derived radioactivity was retained in the body. Dermal penetration of TCB-derived radioactivity was 6-8% of the recovered dose in the four forms, and the major route of excretion was via the feces. Approximately 21% of the absorbed dose was retained in the body at 120 h. Absorption of each chemical applied either as solid, aqueous paste, or suspension was compared to the absorption of the same chemical in ethanol. Absorption of HCB applied as a solid was significantly higher (p less than or equal to .05) as compared to HCB applied in ethanol. There were no other significantly differences in the comparisons of absorption. The data indicate that the chemicals examined in this study can penetrate the skin as readily when applied either as a solid, aqueous paste, or suspension, as when applied in the volatile vehicle ethanol.

A physical approach to the rehabilitation of patients disabled by chronic low back pain.

OBJECTIVE: To report the outcome of a multidisciplinary physically based program to treat sufferers of chronic low back pain who had not responded to previous treatment. DESIGN: Prospective intervention study. SETTING: The treatment program was conducted at the private practice of Brian C Edwards and Associates Rehabilitation Centre. PATIENTS: A total of 54 patients participated in the treatment program. All patients were medically referred. No specific exclusion criteria were used; however, all were not working and had not responded to previous treatment. INTERVENTION: The rehabilitation program consisted of mobilising physiotherapy, isokinetic testing, physical reconditioning, work hardening and psychological testing. This was carried out for seven hours a day, five days a week for four weeks. RESULTS: Of the 54 patients taking part in this trial 30 (55%) were successfully rehabilitated (returned to work) and remained so at a follow-up session one year later. CONCLUSION: While selection criteria for successful rehabilitation have not been established, the results do indicate that such physical rehabilitation programs have an important part to play in the rehabilitation of sufferers of chronic low back pain.

A meta-analytic comparison of the Beck Depression Inventory and the Hamilton Rating Scale for Depression as measures of treatment outcome.

Some clinicians have considered the Beck Depression Inventory, a self-rating scale, too reactive to patient halo effects and, therefore, a liberal measure of treatment outcome. On the other hand, interviewer-rating scales, like the Hamilton Rating Scale for Depression have been viewed as more conservative measures of treatment gain. Studies which compared the Beck Depression Inventory to the Hamilton Rating Scale, as dependent measures, were reviewed for the purpose of determining if the scales provided comparable data for assessing treatment effects. The use of meta-analysis techniques resulted in a comparison of effect sizes which indicated that the Beck Depression Inventory was significantly less liberal than the Hamilton Rating Scale for Depression. The implications of these results for selecting outcome measures and the application of meta-analysis techniques for comparing dependent measures are discussed.

Combined movements in the cervical spine (c2-7) their value in examination and technique choice.

Treatment by passive movement has been shown to be a useful method when compared to other treatment procedures (Edwards 1969). It is however still empirical in nature. Part of the reason for this is because definite movement patterns related to pathology are still unclear. This can produce confusion when one is selecting a technique as very often there appears to be no relationship between the restricted movement the patient may exhibit and the technique chosen. It is suggested that detailed examination related to the combining of different movements will allow a more accurate choice of technique to be made. Under these circumstances the therapist should be able to predict the effect of a treatment technique. Progression of a treatment is also more logical as it depends on progressing the position of the joint to the position which is most painfull as the movement pattern improves, rather than increasing the vigour of the technique.

Combined movements of the lumbar spine: examination and clinical significance.

The aim of this paper is to describe a method of examining the lumbar spine, incorporating the principle of combining movements and relating this to selection of technique. Almost all of the passive movement procedures used in the treatment of the lumbar spine are, in fact, procedures which involve combining or coupling different movements. The importance of examining the lumbar spine using the principles of combining movements is emphasised and it is suggested that this should be a central part of any planned examination. The importance of relating these movements to range and distribution of pain is considered in detail and the application of techniques, rotation in particular is described using positions which involve the combining of different movements.

Personality discriminants of cognitive perception abilities.

Discriminant analyses, using California Psychological Inventory scores, age, and Miller Analogies Test scores, were run on groups of graduate students in counselor training who were high or low on perceptual-cognitive tasks. Twenty male and 23 female Ss watched videotaped sessions in which each of two male and two female expressors talked for three minutes about each of three prescribed subject areas. Perceiver Ss then reacted to a semantic differential as they thought the expressors had previously reacted. Absolute difference scores were established for each S in each of three cognitive dimensions for each expressor sex, and a summary score was also established. Analyses were run on each of these seven scores. Implications for further research and for potential use of the phenomenon were discussed.

Low back pain and pain resulting from lumbar spine conditions: a comparison of treatment results.

In recent issues of the Medical Journal of Australia considerable interest has been shown in manipulation. Dr. B. Gard (1967) has suggested that statistical evidence be obtained from physiotherapy clinics as to the efficiency of manipulative treatment. A symposium was held in 1967 during which the chairman, Dr. Frank May introduced a panel of four speakers, Professor K. C. Bradley, Mr. C. EL Hembrow, Dr. W. Hargrave Wilson and Mr. A. Wright. May in summing up suggested that a new section of the Australian Medical Association be formed to promote interest in manipulative treatment. As a result of this a Victorian State Branch of the Australian Association of Physical Medicine has been formed to further the interest of manipulative treatment within the medical profession.