Tobacco Use and Smoke Exposure in Children: New Trends, Harm, and Strategies to Improve Health Outcomes.

PURPOSE OF REVIEW: Every day in the USA, approximately 4000 adolescents begin smoking and the adolescent brain is particularly susceptible to nicotine addiction. We present current pediatric trends on tobacco use and exposures, various new products used by adolescents, the adverse biological and behavioral effects of tobacco use and exposures, and tobacco control strategies to eliminate tobacco-related illnesses and deaths in the pediatric population. RECENT FINDINGS: Twelve-20% of women continue to smoke during pregnancy. New research reveals cognitive differences and behavior-control disorders are seen in elementary school children from prenatal and postnatal exposures. Traditional cigarette smoking has decreased in adolescents; novel and appealing tobacco products have captured their attention, particularly electronic cigarettes, and rates double and often triple from middle to high school. Children with asthma and those living in multi-housing units have higher rates of secondhand smoke exposure than non-asthmatics and children living in single-home dwellings. There is no "safe or risk-free" level of tobacco use or exposure. Tobacco use and exposure in childhood and adolescence must be decreased using evidenced-based strategies to improve child health.

Enhanced coding in a cochlear-implant model using additive noise: aperiodic stochastic resonance with tuning.

Analog electrical stimulation of the cochlear nerve (the nerve of hearing) by a cochlear implant is an effective method of providing functional hearing to profoundly deaf people. Recent physiological and computational experiments have shown that analog cochlear implants are unlikely to convey certain speech cues by the temporal pattern of evoked nerve discharges. However, these experiments have also shown that the optimal addition of noise to cochlear implant signals can enhance the temporal representation of speech cues [R. P. Morse and E. F. Evans, Nature Medicine 2, 928 (1996)]. We present a simple model to explain this enhancement of temporal representation. Our model derives from a rate equation for the mean threshold-crossing rate of an infinite set of parallel discriminators (level-crossing detectors); a system that well describes the time coding of information by a set of nerve fibers. Our results show that the optimal transfer of information occurs when the threshold level of each discriminator is equal to the root-mean-square noise level. The optimal transfer of information by a cochlear implant is therefore expected to occur when the internal root-mean-square noise level of each stimulated fiber is approximately equal to the nerve threshold. When interpreted within the framework of aperiodic stochastic resonance, our results indicate therefore that for an infinite array of discriminators, a tuning of the noise is still necessary for optimal performance. This is in contrast to previous results [Collins, Chow, and Imhoff, Nature 376, 236 (1995); Chialvo, Longtin, and Müller-Gerking, Phys. Rev. E 55, 1798 (1997)] on arrays of FitzHugh-Nagumo neurons.

A phase model of temperature-dependent mammalian cold receptors.

We present a tractable stochastic phase model of the temperature sensitivity of a mammalian cold receptor. Using simple linear dependencies of the amplitude, frequency, and bias on temperature, the model reproduces the experimentally observed transitions between bursting, beating, and stochastically phase-locked firing patterns. We analyze the model in the deterministic limit and predict, using a Strutt map, the number of spikes per burst for a given temperature. The inclusion of noise produces a variable number of spikes per burst and also extends the dynamic range of the neuron, both of which are analyzed in terms of the Strutt map. Our analysis can be readily applied to other receptors that display various bursting patterns following temperature changes.

Collaborative study for the quality control of trace element determinations in paint coatings. Part 2. Certification of alkyd resin paint reference materials for the migratable contents of trace elements (CRMs 620 and 623).

This paper describes the preparation, homogeneity studies and certification of a series of two paint reference materials (mild steel coated with alkyd resin paint, CRM620, and comminuted paint from alkyd resin paint, CRM623) which have been produced in support of the EU Toy Safety Directive (88/378/EEC). The reference materials have been certified for levels of toxic element migration using the method specified in European Standard EN71-3:1994 published by the European Committee for Standardization. As such, the certified values, indicative values and range data quoted for the reference materials in this paper are method specific and relate only to European Standard EN71-3:1994. The paper summarizes the analytical work carried out and gives a description of the analytical methods used to measure As, Ba, Cd, Cr, Hg, Pb, Sb and Se, the 8 toxic elements specified in European Standard EN71-3:1994, in the sample extracts. Descriptions of the reference materials, certified values, indicative values together with their associated uncertainties or range of laboratory means as appropriate are given. The preparation of a (not certified) reference material (beechwood coated with nitrocellulose paint, RM621) is also described and assigned values for As, Ba, Cd and Se are given. The Hg content could not be certified in any of the reference materials, owing to a high dispersion of results.

Stable, continuously tunable operation of a diode-pumped doubly resonant optical parametric oscillator.

We demonstrate, for what is the first time to our knowledge, long-term stable, continuously tunable operation of a doubly resonant optical parametric oscillator (OPO) pumped by a single-stripe diode laser without the use of an external semiconductor amplifier. The OPO is based on periodically poled lithium niobate and is pumped by a 150-mW distributed Bragg grating diode laser. 18-mW total output power is generated at 1.3- and 2.3-mum wavelengths. A cavity-length servo system allows continuous signal tuning of 17 GHz and idler tuning of 10 GHz, limited only by the range of a piezoelectric cavity mirror mount. OPO tuning is demonstrated from 1.1 to 1.4 mum and from 2.2 to 3.7 mum.

A follow-up study of infants < or = 2000 g birthweight treated in central Queensland.

OBJECTIVE: This follow-up study was undertaken in an effort to ascertain the morbidity in the survivors of infants < or = 2000 g birthweight cared for in the two Rockhampton intensive care nurseries. METHODOLOGY: The records of all infants < or = 2000 g delivered in or transferred to Rockhampton during the 11 year period 1979 through 1989 inclusive were extracted. Efforts were made to contact and examine all of these children. Those found to be disabled were assessed as being mildly, moderately or severely affected. RESULTS: Of the 482 infants of birthweight < or = 2000 g treated in the period under review, 393 survived to be discharged from hospital. Eight were known to have died subsequently. Of the remaining 385 children, 288 (74.8%) were able to be contacted and their health status determined. A total of 36 infants were found to have significant disabilities. Twenty-four were mildly affected, five moderately and seven severely affected. Severe disability in infants of < or = 1000 g was 16% (3/19). CONCLUSIONS: The incidence of disability was established in 74.8% of the surviving population. It was not dissimilar to the incidence of disability in similar birthweight groups in some Australian tertiary centres for the years under study. It is emphasized that the follow-up was incomplete and recognized that the survival rates and incidence of disability in survivors has improved in tertiary centres since the time frame of this study.

Identification of a mobile intracardiac rheumatoid nodule mimicking an atrial myxoma.

Cardiovascular involvement occurs in 30% to 50% of patients with rheumatoid arthritis and typically presents as nonspecific inflammation or fibrosis of cardiac structures or as nodules embedded in the various cardiac tissues. This case report describes a unique pedunculated, mobile left atrial rheumatoid nodule prolapsing through the mitral valve plane and mimicking an atrial myxoma. A brief discussion of intracardiac rheumatoid nodules and their potential significance follows.

Survival of low birthweight infants in central Queensland.

The survival of low birthweight infants < or = 2000 g born in the central Queensland area during the years 1979 to 1991 was examined. Five hundred and sixty such infants were either delivered at one of the two Rockhampton obstetric units (Rockhampton Base Hospital and the Mater Misericordiae Hospital) or retrieved from outlying central Queensland areas. Both hospitals had intensive care nurseries capable of ventilation and infants were transferred to tertiary centres only for cardiac or surgical treatment. The study involved all liveborn infants, including those with lethal malformations and all deaths up to the time of discharge. Survival rates were as follows: < or = 500 g 0%, 501 < or = 750 g 30%, 751 < or = 1000 g 51%, 1001 < or = 1500 g 79%, 1501 < or = 2000 g 93%. The survival of Aboriginal infants and outborn infants were found to be essentially the same as the overall group.

Renal cell cancer among paperboard printing workers.

A physician's alert prompted us to investigate workers' cancer risk at a paperboard printing manufacturer. We conducted a retrospective cohort mortality study of all 2,050 persons who had worked at the facility for more than 1 day, calculated standardized incidence ratios (SIRs) for bladder and renal cell cancer, and conducted a nested case-control study for renal cell cancer. Standardized mortality ratios (SMRs) from all causes [SMR = 1.0, 95% confidence interval (CI) = 0.9-1.2] and all cancers (SMR = 0.6, 95% CI = 0.3-1.0) were not greater than expected. One bladder cancer and one renal cell cancer were included in the mortality analysis. Six incident renal cell cancers were observed, however, compared with less than two renal cell cancers expected (SIR = 3.7, 95% CI = 1.4-8.1). Based on a nested case-control analysis, the risk of renal cell cancer was associated with overall length of employment but was not limited to any single department or work process. Although pigments containing congeners of dichlorobenzidine and o-toluidine had been used at the plant, environmental sampling could not confirm any current exposure. Several limitations and a potential selection bias limit the inferences that can be drawn.

Chevalier Taylor--Ophthalmiater Royal (1703-1772).

John Taylor was surgeon-oculist to King George II, and claimed to be Ophthalmiater Royal to the Pope and to the Emperor, along with a multitude of royalties, including a mythical Princess of Georgia and the Viceroy of the Indies. He was the first and last ophthalmologist to travel from court to court of Europe with a cavalcade of outriders and supporters; and although he was caricatured as a mountebank, there was an element of genius about him, and his innovations, especially in squint surgery, demand that he should not be forgotten.

Malignant salivary gland tumors of the base of the tongue.

We present a 41-year retrospective study of patients with malignant salivary gland tumors of the base of the tongue treated at The University of Texas M. D. Anderson Hospital and Tumor Institute at Houston. This report characterized the patient group, documents their physical findings, analyzes survival, and draws some conclusions regarding clinical course and treatment options. When feasible, surgical resection is the preferred treatment, with planned postoperative radiotherapy when indicated by pathologic findings.