Developmental Toxicity of Dimethylacetamide by Inhalation in the Rat

Developmental Toxicity of Dimethylacetamide by Inhalation inthe Rat. SOLOMON, H. M., FERENZ, R. L., KENNEDY, G. L., ANDSTAPLES, R. E. (1991). Fundam. Appl. Toxicol. 16, 414–422.Dimethylacetamide (DMAC) is a widely used industrial solvent.It has been reported to be teratogenic when given to rats byinjection or following dermal application. Most of these studiesemployed large single doses and did not examine both the fetaland the maternal response. In this study, groups of pregnantCrl:CD rats were exposed to 32, 100, or 282 ppm DMAC by inhalationfor 6 hr/day from Days 6 through 15 of gestation (day on whichcopulation plug was detected was termed Day 1G). A control groupof chambered pregnant rats was exposed simultaneously to aironly. All female rats were euthanized on Day 21G. At 282 ppm,both maternal weight gain during the exposure period and fetalweight were significantly decreased and accompanied by a significantdose-response trend. These effects were not seen in rats inhalingeither 32 or 100 ppm. Fetal resorptions were not increased inany of the groups exposed to DMAC. Fetal incidences of external,visceral, or skeletal variations and malformations were similarbetween the test and control groups. Therefore, both fetal andmaternal toxicity were noted at 282 ppm and the no-observedadverse-effect level under these experimental conditions was100 ppm for both the dam and the conceptus. DMAC was not demonstratedto produce malformations in the rat fetus even at a level thatwas toxic to the dam.     

Psychiatry in the allergy clinic: the nature and management of patients with non-allergic symptoms

Patients with multiple unexplained somatic symptoms attributed to allergy frequently present to physicians and often the physician fails to find evidence for allergic or immunological mechanisms underlying the presenting symptoms. This article discusses the social and cultural background to this disorder. We then consider current explanatory models for symptoms and finally, we consider appropriate management, starting with the initial consultation, the identification of psychiatric disorders when present, and concluding with suggestions for subsequent treatment and guidance on appropriate referral.     

The use of a low phenylalanine diet with amino acid supplement in the treatment of behavioural problems in a severely mentally retarded adult female with phenylketonuria

ABSTRACT. If phenylketonuria is untreated in infancy, it causes irreversible brain damage. No dietary treatment can alter this brain damage. However, it has been shown that dietary treatment can reduce behaviour disturbances often associated with the condition. In this study, a subject's behaviour was monitored over 18 weeks while on a low phenylalanine diet. Results demonstrate a significant reduction in the level of her disturbed behaviour.     

Respiratory obstruction after posterior fossa surgery

We report a case of acute upper airway obstruction after tracheal extubation 24 hours after surgery. The respiratory complications of surgery for posterior fossa lesions are discussed.     

Use of the rocking bed in the treatment of neurogenic respiratory insufficiency

We describe 53 patients who received ventilatory support witha rocking bed. Diagnoses included previous poliomyelitis (30),muscular dystrophy (12), motor neurone disease (4), adult-onsetacid maltose deficiency (4) and a miscellaneous group (3). Patientspresented with respiratory insufficiency characterized by diaphragmweakness, progressive nocturnal hypoventilation and/or acuteor chronic respiratory failure. Domiciliary rocking beds wereused by 43 patients for a mean of 16.0 years (range 1 monthto 35 years). Most patients were able to breathe adequatelyby day when sitting or standing, but needed assistance by rockingbed for 6–11 h when lying down for sleep. The rockingbed was well-tolerated, and associated with both symptomaticrelief and amelioration of arterial blood gas abnormalities.Seventeen of these 43 patients discontinued its use, eitherbecause of discomfort (9) or increasing respiratory insufficiency(8). The rocking bed is a valuable adjunct in the managementof the respiratory insufficiency associated with neuro-musculardisease.     

In Vivo and in Vitro Percutaneous Absorption and Skin Decontamination of Arsenic from Water and Soil

The objective was to determine the percutaneous absorption ofarsenic-73 as H₃A_sO₄ from water and soil. Soil (Yolo County65-California-57-8) was passed through 10-, 20-, and 48-meshsieves. Soil retained by 80 mesh was mixed with radioactivearsenic-73 at a low (trace) level of 0.0004 µg/cm² (microgramsarsenic per square centimeter skin surface area) and a higherdose of 0.6 µg/cm². Water solutions of arsenic-73 at alow (trace) level of 0.000024 µg/cm² and a higher doseof 2.1 µg/cm² were prepared for comparative analysis.In vivo in Rhesus monkey a total of 80.1 ± 6.7% (SD)intravenous arsenic-73 dose was recovered in urine over 7 days;the majority of the dose was excreted in the first day. Withtopical administration for 24 hr, absorption of the low dosefrom water was 6.4 ± 3.9% and 2.0 ± 1.2% fromthe high dose. In vitro percutaneous absorption of the low dosefrom water with human skin resulted in 24-hr receptor fluid(phosphate-buffered saline) accumulation of 0.93 ± 1.1%dose and skin concentration (after washing) of 0.98 ±0.96%. Combining receptor fluid accumulation and skin concentrationgave a combined amount of 1.9%, a value less than that in vivo(6.4%) in the Rhesus monkey. From soil, receptor fluid accumulationwas 0.43 ± 0.54% and skin concentration was 0.33 ±0.25%. Combining receptor fluid plus skin concentrations gavean absorption value of 0.8%, an amount less than that with invivo absorption (4.5%) in the Rhesus. These absorption valuesdid not match current EPA default assumptions. Washing withsoap and water readily removed residual skin surface arsenic,both in vitro and in vivo. The partition coefficient of arsenicin water to powdered human stratum corneum was 1.1 x 10⁴andfrom water to soil it was 2.5 x 10⁴. This relative similarityin arsenic binding to powdered human stratum corneum and soilmay indicate why arsenic absorption was similar from water andsoil. This powdered human stratum corneum partition coefficientmodel may provide a facile method for such predictions.