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.     

Vesicocutaneous fistula: An unusual complication of inguinoscrotal hernia

Involvement of the urinary bladder in an inguinal hernia is common, but massive bladder hernia is rare. Most urinary bladder herniations are discovered and repaired during surgery. We report a case of large incarcerated inguino-scrotal hernia, which was reduced only to present as a scrotal abscess and vesicocutaneous fistula; an unusual complication. The patient was managed conservatively due to underlying comorbidities.     

Dental diagnosis and treatment for musicians

Oral health maintenance for the musical performer is an essential component of the training and experience. Normal tooth and dental arch development permit vocalists. and players of wind instruments and chin-held wind instruments to achieve their optimum acoustic and esthetic musical performance. Dental disease or disorders that high-quality performance years of vocalists and instrumentalists.     

The Effect of 50 Hz External Electrical Interference on Implanted Cardiac Pacemakers

The effects of injected 50 Hz alternating current on the function of cardiac pacemakers has been observed in 18 patients with implanted unipolar VVI units. Current, in the range 0-600 microA was applied via electrodes attached to the patients' upper body and feet and fed from a specially designed current injection unit at the bedside. Most implanted pacemakers reverted to interference mode in the current range 29-250 microA. At current levels just below the reversion current all units developed irregular and inappropriate pacing. This current level was pacemaker dependent and varied in the range 27-246 microA. The total reversion current depended on the location of the injecting electrodes and on the patients' posture. The sensitivity of the units to injected interference was increased by deep inspiration. Temporary pacing catheters fitted to an additional ten patients were used to monitor the interference voltage which would be sensed by an implanted unit. This voltage was similarly dependent on patient posture and on deep respiration. Current injection has proved to be a safe, controllable and reproducible method of testing the sensitivity of implanted pacemakers to 50 Hz external interference.     

Changes in levels of alcohol consumption: United States, 1983–1988

Using data from the 1983 and 1988 National Health Interview Surveys, this note examines changes both in the prevalence of abstention and the prevalence of heavier drinking among drinkers in the United States. Changes are examined separately by gender and according to other sociodemographic characteristics often associated with different levels of alcohol consumption. Results suggest an increase in abstention and a decrease in heavier drinking between 1983 and 1988. For women, decreases in heavier drinking were found among those 18-44 years of age, among those employed, and among those divorced/separated or never married. For men, decreases in heavier drinking were found among those employed, among those with family income of $25000 or more, and among those married or divorced/separated. Changes both in abstention and heavier drinking were found to vary considerably by geographical region. These findings do not support results from other general population survey studies on alcohol use that suggest a stability in drinking levels, or even a slight increase in heavier drinking among men.     

Planning health sector expenditure in support of PHC

This paper describes an approach to financial control whichhas been common to the public sector health services in a numberof countries and it identifies some problems it presents tothe effective implementation of PHC development policies. Amongthe functions of existing systems are the control of expenditure,monitoring for theft and annual budgeting. As the health sectoris transformed from a relatively simple, urban-based serviceto one undertaking activities throughout the country, adaptationswill be required. Furthermore, in order to oversee a significantchange in the pattern of resource allocation, it will be necessaryto integrate the planning system more closely with the preparationof the budget and with the approaches to financial control.While the focus is on the need to strengthen the instrumentsfor resource management within the public services, the importanceof taking a broader view of the health sector is recognized.Those responsible for assuring the effective use of scarce resourcesmust take cognisance of the impact of private health activitieson PHC development. Some implications which this has for plannersare explored.     

Lack of Delayed Neurotoxic Effect after Tri-o-cresyl Phosphate Treatment in Male Fischer 344 Rats: Biochemical, Neurobehavioral and Neuropathological Studies

Lack of Delayed Neurotoxic Effect after Tri-o-cresyl PhosphateTreatment in Male Fischer 344 Rats: Biochemical, Neurobehavioral,and Neuropathological Studies. SOMKUTI, S. G., TIL-SON, H. A.,BROWN, H. R., CAMPBELL, G. A., LAPADULA, D. M., AND ABOU-DONIA,M. B. (1988). Fundam. Appl. Toxicol. 10, 199-205. Tri-o-cresylphosphate (TOCP), which produces a delayed neurotoxic syndromein humans and some animal species, was given to Fischer 344(F344) male (18 week old) rats to determine if it causes biochemical,sensorimotor, and neuropathological effects. Animals were givenTOCP by gavage in doses ranging from 10 to 100 mg of TOCP/kgdaily for a period of 63 days. The rats were subjected to aseries of neurobehavioral tests including fore- and hindlimbgrip strength, motor activity, tremor, and latency to respondto a thermal stimulus. Central and peripheral nervous tissueswere examined for damage characteristic of organophosphorouscompound-induced delayed neurotoxicity (OPIDN). Brain neurotoxicesterase and acetylcholinesterase activities were inhibitedin a dose-dependent fashion. A group of three chickens treatedwith 100 mg of TOCP/kg/day for 18 days was included as the positivecontrol for enzymatic and histopathological alterations associatedwith OPIDN. Rats showed no consistent neurobehavioral changesor evidence of neuropathological damage in nervous tissues associatedwith treatment. In contrast, chickens treated with TOCP developeddelayed neurotoxicity characterized by ataxia, which progressedto paralysis. These neurological changes included swelling,fragmentation, and degeneration of the axon and myelin in bothcentral and peripheral nervous tissues. This study concludesthat the F344 rat is not sensitive to the delayed neurotoxiceffects of TOCP. When studying OPIDN in rats, care must be exercisedin choosing the experimental animal since some strains, e.g.,F344, are not sensitive.     

The role of auxiliary dihydropyridine receptor subunits in muscle

The skeletal muscle dihydropyridine receptor is a slowly-activating calcium channel that functions as the voltage sensor in excitation-contraction coupling. In addition to the pore-forming α_1S subunit it contains the transmembrane α₂δ-1 and γ₁ subunits and the cytoplasmic β_1a subunit. Although the roles of the auxiliary subunits in calcium channel function have been intensively studied in heterologous expression systems, their functions in excitation-contraction coupling has only recently been elucidated in muscle cells of various null-mutant animal models. In this article we will briefly outline the current state of these investigations. * To whom correspondence should be addressed: Tel.: +43-512-507-3787; Fax: +43-512-507-2836; E-mail: bernhard.e.flucher@uibk.ac.at     

Neurotoxicity Evaluation of N,N-Diethyl-m-toluamide (DEET) in Rats

The neurotoxic potential of N,N-diethyl-m-toluamide (DEET) wasevaluated following acute oral administration or following multigenerationplus chronic dietary administration to the rat. For the acutestudy, rats were administered undiluted DEET at dose levelsof 50, 200, or 500 mg/kg by gavage. A dose level of 500 mg/kgwas considered to be the highest practical dose that could beevaluated in this study based upon observations of overt toxicityat 500 mg/kg and mortality at 1000 mg/ kg in a dose range-findingstudy. The two measures of neurotoxicity evaluated in the acutestudy were functional observational battery (FOB) and motoractivity measurements. An apparent treatment-related effectin thermal response time (increased) was noted for both sexes1 hr after dosing at the 500 mg/kg dose level. A questionableeffect on rearing activity (decreased) also was noted at thesame dose level. For the multigeneration plus chronic dietaryadministration study, rats were administered DEET at dietaryconcentrations of 0, 500, 2000, or 5000 ppm continuously overtwo generations and then chronically for 9 months. A dietaryconcentration of 5000 ppm meets the criteria for a maximum tolerateddose (MTD) based on traditional chronic toxicology assessments.Evaluations included FOB, motor activity, discriminative acquisitionand reversal in an Mmaze, acoustic startle habituation, passiveavoidance acquisition and retention, and microscopic examinationof central and peripheral nervous tissue. The only effect thatwas considered to be possibly treatment-related was a slightincrease in exploratory locomotor activity at the 5000 ppm doselevel. Based on the results of these studies, the nervous systemdoes not appear to be a selective target when DEET is administeredto rats either as a single oral dose at high dose levels orchronically at the MTD.