Substance use among Dutch dental students.

OBJECTIVES: The objectives were to assess the prevalence of substance use among Dutch dental students and to determine their attitudes about substance use and its consequences. METHODS: In association with a national study of drug use among US dental students, a questionnaire was translated from English into Dutch and administered to dental students at two dental schools in The Netherlands. Students received an anonymous 115-item questionnaire in the fall of 1996. RESULTS: Alcohol was the students' drug of choice for lifetime (95%), past year (94%) and past month (88%) use. No significant correlations were found between alcohol use and gender, schools, and years in dental education. In the past month, 58% of students reported drinking on 5 or more days; 53% had 5 or more drinks on the same occasion, 20% had 5 or more drinks on the same occasion on 5 or more days; and 17% reported getting drunk at least monthly. Prevalence rates for past month use of tobacco was 24% and marijuana, 4%. Male students smoked twice as much as females, with significant differences found for all three periods of use (X2>19.00, P<0.01). When asked whether their schools offered policies and education programs on alcohol and other drugs, 52% of students reported that these were not available. CONCLUSIONS: Dental schools should develop effective programmes to educate students about responsible use of alcohol and other licit and illicit drugs. Schools should also inform students about their susceptibilities to substance abuse and dependency.

Voxel significance mapping using local image variances in subtraction ictal SPET.

Subtraction ictal SPET co-registered to MRI (SISCOM) has been shown to aid epileptogenic localization and improve surgical outcome in partial epilepsy patients. This paper reports a method of identifying significant areas of epileptogenic activation in the SISCOM subtraction image, taking into account normal variation between sequential 99Tcm-ethyl cysteinate diethylester SPET scans of single individuals, and attempts to assess the clinical value of statistical mapping in subtraction SPET. Non-linear inter-subject registration is used to combine a group of subtraction images into a common anatomical framework. A map of the pixel intensity standard deviation values in the subtraction images is created, and this map is non-linearly registered to a patient's SISCOM subtraction image. Pixels in the patient subtraction image were then evaluated based upon the statistical characteristics of corresponding pixels in the atlas. SISCOM images created with the voxel variance method were rated higher in quality than the conventional image variance method in 15 patients. No difference in localization rate was observed between the voxel variance mapping and image variance methods. The voxel significance mapping method was shown to improve the quality of clinical SISCOM images.

The influence of a workshop on dental students' perceptions about sexual harassment.

The objective of this study was to determine the effects of a workshop on the sexual harassment perceptions of students at the University of Kentucky College of Dentistry. Responses to a twenty-six-item questionnaire were elicited from 147 first-through fourth-year students before and after they attended a two-hour sexual harassment workshop. Five questions explored students' personal experiences with sexual harassment; twenty-one questions addressed students' attitudes about sexual harassment. The repeated measures option of the SPSS General Linear Model statistical program was used to individually analyze the Likert-type scale response to the twenty-one attitude items for the following variables: gender, year in dental education, and whether respondents had been sexually harassed or had observed harassment of others. Workshop participation significantly changed some student attitudes about sexual harassment regardless of gender, year in dental education, or whether they had been harassed personally or had witnessed harassment of someone else (p < .05). There were also significant gender-related differences in the direction and magnitude of change in pre- versus post-workshop responses to several attitude items (p < .05). Workshop participants were better informed about and more sensitive to a wide range of sexual harassment issues. The workshop empowered students, especially females, to help create an environment that minimizes the probability of sexual harassment. This may be possible because, after the workshop, participants better understood institutional policies and procedures to handle complaints, including provisions for protection from retaliation if they do file a grievance. This knowledge and sensitivity may result in an environment that facilitates the education of beginning general practitioners who are competent, empathetic, and sensitive.

Dental students' sexual harassment experiences and attitudes.

The objective of this study was to describe the sexual harassment experiences and attitudes of students at the University of Kentucky College of Dentistry. A twenty-six-item questionnaire was developed and administered to 170 dental students in years one through four of the curriculum. Five questions explored students' personal experiences with sexual harassment--whether they had been harassed or had observed harassment; twenty-one questions addressed students' attitudes about sexual harassment. Computations of mean differences in Likert-type scale responses for the twenty-one attitude items were completed using independent t-tests for the following variables: gender, whether respondents had been sexually harassed or had observed harassment of others, and years in dental education. Almost 15 percent of the students reported being sexually harassed at least once in dental college. Females were sexually harassed more often than males (p < .01), and second, third, and fourth year students more often than first year students (p < .05). Additionally, 30 percent of the students reported witnessing sexual harassment in the college. Harassers included faculty (88 percent), dental students (8 percent), and others (4 percent). Differences (p < .05) in sexual harassment attitudes were found when responses were analyzed by gender, by whether students had been sexually harassed, by whether they had witnessed harassment, and by years in dental education. The data show that sexual harassment occurs in the college. Dental faculty and students could benefit from programs to educate them about sexual harassment, how to prevent it from occurring, and how to respond if they are sexually harassed.

Does electrical stimulation of deaf cochleae prevent spiral ganglion degeneration?

Thirty-six drug deafened guinea pigs were studied to determine how electrical stimulation of the cochlea affects spiral ganglion cell (SGC) survival. Animals were divided into two groups, extracochlear and intracochlear stimulation, and each group was further divided into four stimulus subgroups: no stimulation (implanted controls), the inferior colliculus electrically evoked potential (ICEEP) threshold-2 dB, ICEEP threshold+2 dB, and ICEEP threshold+6 dB. Stimuli consisted of 200 micros/phase charge balanced biphasic current pulses presented at 100 pulses per second using monopolar stimulation. Animals were stimulated 5 h/day, 5 days per week, for 8 weeks. The animals were then perfused and the cochleae serially sectioned at 4 microm saving every 8th section. We counted the number of intact SGCs, those containing a nucleus with chromatin, in each 20% segment of the cochlea and also measured SGC densities (number of neurons per mm2 of Rosenthal's canal). The number of surviving spiral ganglion neurons was not significantly different (P > 0.05) between the implanted and the unimplanted ears in any of the experimental groups. However, the spiral ganglion neuron densities were significantly elevated in the electrically stimulated ears (P < 0.001) but not in the implanted but not chronically stimulated ears (P > 0.05). We measured the volume of Rosenthal's canal in one subgroup (ICEEP threshold+2 dB) and found a decrease in this volume in the stimulated ear compared to the unstimulated ear (P < 0.01). These findings support the hypothesis that chronic monopolar electrical intracochlear or extracochlear stimulation is not a neurotrophic factor, increasing spiral ganglion neuron survival, but instead causes a narrowing of Rosenthal's canal that accounts for the increased spiral ganglion neuronal densities seen in the stimulated cochleae.

Auditory brainstem responses of CBA/J mice with neonatal conductive hearing losses and treatment with GM1 ganglioside.

Exogenous administration of GM1 ganglioside to CBA/J mice with a neonatal conductive hearing loss ameliorates the atrophy of spiral ganglion neurons, ventral cochlear nucleus neurons, and ventral cochlear nucleus volume. The present investigation demonstrates the extent of a conductive loss caused by atresia and tests the hypothesis that GM1 ganglioside treatment will ameliorate the conductive hearing loss. Auditory brainstem responses were recorded from four groups of seven mice each: two groups received daily subcutaneous injections of saline (one group had normal hearing; the other had a conductive hearing loss); the other two groups received daily subcutaneous injections of GM1 ganglioside (one group had normal hearing; the other had a conductive hearing loss). In mice with a conductive loss, decreases in hearing sensitivity were greatest at high frequencies. The decreases were determined by comparing mean ABR thresholds of the conductive loss mice with those of normal hearing mice. The conductive hearing loss induced in the mice in this study was similar to that seen in humans with congenital aural atresias. GM1 ganglioside treatment had no significant effect on ABR wave I thresholds or latencies in either group.

The deafness locus (dn) maps to mouse chromosome 19.

The deafness mouse has profound sensorineural hearing loss with degeneration of hair cells soon after birth. The mode of inheritance is recessive, and there are no associated phenotypic anomalies. Thus, this mouse provides a model for recessive, non-syndromic, prelingual deafness. We have mapped the gene causing deafness in the mouse to Chromosome (Chr) 19 by analysis of 230 intersubspecific backcross progeny. No recombinants were found with the microsatellite marker D19Mit14. The loci for two guanine nucleotide-binding proteins are tightly linked to this marker, and they are being investigated as possible candidate genes. The identification of the defective gene in the mouse will help to explain the mechanism that causes hair cell degeneration and is likely to identify a homologous gene for deafness in humans.

Exogenous GM1 ganglioside effects on conductive and sensorineural hearing losses.

Both CBA/J mice with neonatal cochlea removals and CBA/J mice with neonatal atresias of the external auditory meatus have significantly smaller ventral cochlear nucleus is greater in the mice with cochlea removals, but the soma area reduction is greater in the mice with external auditory meatus atresias. GM1 gangliosides were subcutaneously injected daily into a group of CBA/J mice with conductive hearing loss caused by neonatal removals of their left external auditory meatus, and into a group of CBA/J mice unilaterally deafened by left cochlea removals. In the mice with conductive hearing loss, the ganglioside treatment significantly ameliorated the atrophy of spiral ganglion neurons, ventral cochlear nucleus neurons, and ventral cochlear nucleus volume. In unilaterally deafened mice, the ganglioside treatment had no measurable effect on the atrophy of ventral cochlear nucleus neurons or of ventral cochlear volume. It is suggested that GM1 ganglioside treatment potentiates growth factors which sustain spiral ganglion integrity and that this sustained activity of the spiral ganglion in turn maintains the integrity of the cochlear nuclei.

Mice heterozygous for the deafness gene have normal auditory thresholds.

Cochlear degeneration in the early postnatal period has been reported as a homozygous recessive mutation in deafness (dn/dn) mice of the curly-tail stock. Heterozygous (+/dn) mice of the same population exhibit hearing when tested by the Preyer reflex, and their cochlear morphology appears normal by light microscopy. However, whether the heterozygote's unmatched recessive deafness allele has deleterious effects not detected by this reflex has not been examined. This study compares the ABR thresholds of presumed homozygous dominant (+/+) and known heterozygous (+/dn) deafness mice, as well as CBA/J mice. Hearing thresholds in the heterozygotes were not significantly different from those of presumed homozygotes or CBA/J mice. A 'generational backtracking' method was used to increase the probability of identifying homozygous (+/+) animals of the curly-tail strain.

Degeneration followed by partial regeneration of the organ of Corti in deafness (dn/dn) mice.

The deafness mouse is a Mendelian recessive mutant which never hears and has no stimulus-related receptor or neural auditory responses. From birth through 12 days after birth (DAB), the organ of Corti develops normally as seen with light microscopy, except that the space of Nuel does not fully develop. The inner and outer hair cells are degenerating between 12 and 24 DAB and are gone by 45 DAB. As the hair cells degenerate, other cells of the organ of Corti become less recognizable, appear to collapse, and lose their identities as differentiated cells. By 45 DAB, from base to apex, the organ of Corti is composed of a low, roughly cuboidal epithelium with no distinguishing cell types; a hint of a tunnel of Corti remains at the apex. In the basal turn, the organ of Corti remains in this degenerated state through at least 460 DAB (senility for these mice). In the apical organ of Corti, considerable regeneration occurs between 45 and 90 DAB. By 90 DAB the apical turn of the organ of Corti has readily identifiable inner and outer pillar cells, inner and outer supporting cells, Hensen's cells, and Claudius' cells. A tunnel of Corti and space of Nuel are also present in the apex but there are no hair cells. Mechanisms are not known for either the degeneration or the regeneration.

Neonatal conductive hearing loss does not compromise brainstem auditory function and structure in rhesus monkeys.

The effect of conductive hearing loss on the maturation of the auditory pathway was evaluated using the auditory brainstem response (ABR) in rhesus monkeys. Ten newborn rhesus monkeys were assigned to control (N = 4), unilateral hearing loss (N = 3), or bilateral hearing loss (N = 3) groups. Hearing loss was created by surgically excising a 3 mm section of the external auditory canal and suturing the canal. Auditory brainstem responses to click stimuli were recorded prior to and after the surgical procedure and bi-monthly or monthly for a 14 month follow-up period. Results showed that after surgery all ears developed an estimated 30-50 dB conductive hearing loss which was retained throughout the follow-up period. Contrary to expectations, the latencies of the ABR component waves decreased with age in all ears. When adjusted for hearing level, there were no differences between ears in maturation of the component waves of the ABR. These data suggest that, in primates, a conductive hearing loss does not affect the maturation of those aspects of the auditory pathway reflected in the ABR. Furthermore, the conductive losses were not accompanied by any discernible change in the neuronal sizes of brainstem auditory neurons or the volume of the cochlear nuclei.

Reversible conductive hearing loss in mice.

Fibrin tissue adhesive was injected into the right ears of four 7-week-old CBA/J mice. Auditory brain stem responses (ABRs) were used to monitor changes in auditory sensitivity over the next 26 days, after which the middle ears and cochleas were examined histologically. Mean maximum ABR threshold shifts were as great as 36 dB, and were larger for higher frequencies than for lower. Maximum shifts occurred between 1 and 8 days; by 26 days, thresholds had returned to intensity levels observed before injection.

Conductive hearing loss affects the growth of the cochlear nuclei over an extended period of time.

During normal growth in CBA/J mice, the volume of dorsal and ventral cochlear nuclei change very little between 1 and 3 days of age; then more than double between 6 and 12 days of age. After 12 days, the rate of growth declines, but growth continues through at least 90 days. The globular cells of the ventral cochlear nucleus also double their soma areas between 6 and 12 days, but then grow no more. The number of ventral cochlear nucleus neurons containing Nissl substance doubles between 6 and 12 days of age and then remains stable. This increase in neuronal numbers is probably caused by differentiation of neuroblasts into neurons, not by mitoses. Conductive losses from 4 to 45 days, and from 24 to 45 days, both result in reduced volume of the ventral cochlear nucleus, but have no effect on the volume of the dorsal cochlear nucleus. Globular cell area is affected by a conductive loss from 4 to 45 days of age, but not by a conductive loss from 24 to 45 days. Therefore, conductive losses affect neuropil growth beyond the time when soma size is no longer affected by these losses.

Sound amplification negates central effects of a neonatal conductive hearing loss.

Neonatal CBA/J mice with external auditory meati removed were raised in a sound-amplified environment. If amplification continued until sacrifice at 24 or 45 days of age, both cochlear nuclear volumes and cross-sectional areas of VCN globular cells were of normal size; without amplification both measurements were significantly reduced.

Morphological and electrophysiological study of the inner ear and the central auditory pathways following whole body fetal irradiation.

Pregnant CBA/CBA mice were whole body irradiated with 2 Gy on the 13th or 16th day of gestation, respectively. The exposed fetuses were raised to an age of 21 postnatal days. Auditory brainstem recordings of threshold levels showed a considerable elevation independent of if irradiation had been performed on either the 13th gestational day or the 16th gestational day. In exposed animals a latency difference occurs in the peaks that increases from peak 1 to peak 5, measuring in peak 5 up to 1.16 ms. Also the peak-to-peak length of waves 1-5 increases in irradiated animals. Scanning electron microscopy of the cochleae showed varying degrees of stereociliary derangement of both outer and inner hair cells, particularly in cochleae where irradiation had been performed on the 13th gestational day, but not loss of hair cells. Light microscopic analysis of auditory brainstem nuclei revealed normal conditions except that in inner ears exposed on the 16th gestational day the flocculus was fused to the lateral surface of the anterior ventral cochlear nucleus. It is concluded that the elevated threshold levels in irradiated animals are most likely due to pathological changes in the peripheral receptor organ whereas the increased latencies and the increased peak-to-peak length likewise reflect functional changes in the brainstem auditory nuclei.

Caries and treatment patterns in children related to school lunch program eligibility.

This article presents the caries prevalence and treatment patterns of children relative to a classification of family economic status, based on the child's eligibility for the free or reduced-cost school lunch program. Dental caries prevalence is reported for children aged 8-11 years at the beginning of a longitudinal clinical trial in the nonfluoridated city of Tampa, Florida. These children were placed into one of three school lunch subsidy categories--poverty, near-poverty, and nonpoverty--using federal government income eligibility guidelines for the school lunch program. The results support an inverse relation of caries prevalence to economic status, as well as the expected direct relation of family income to treatment needs met. The nonpoverty group exhibited the lowest number of decayed surfaces and had nearly 70 percent of their treatment needs met. The poverty group had significantly higher scores both for total caries experience (DMFS) and decayed surfaces (DS) than either of the other groups. Filled surfaces (FS) scores were not significantly different for any of the groups. This method of classifying children by school lunch program eligibility is considered valid because of the rigorous requirements used in determining family income, as well as the thorough verification procedure that is applied. The method is easy to use once officials have been convinced that confidentiality will be maintained.

Incomplete maturation of brainstem auditory nuclei in genetically induced early postnatal cochlear degeneration.

In the Shaker-2 mouse mutant, a cochleo-saccular type of genetically induced inner ear degeneration occurs. Morphological signs of degeneration are evident in the 3rd postnatal week and a severe and almost total degeneration has occurred by the age of 6-9 weeks. There are no qualitative differences between the brain of the normal CBA/J mouse and that of the Shaker-2 mouse. The growth of the auditory brainstem nuclei (dorsal cochlear nucleus and ventral cochlear nucleus) in the mutant Sh-2 mouse has stopped by 14 days of age--but not in the normal CBA/J mouse. The brainstem as a whole continues to grow between 14 and 140 days of age in both strains. The early cochlear degeneration coincides with the critical period when a normal input from the peripheral receptor organ is necessary for the maturation of the central auditory pathway.

The spiral ganglion and cochlear nuclei of deafness mice.

Deafness mice (dn/dn) never develop hearing, but, except for the associated physical defects, have no other known abnormalities. For this study, cochleas and brains of five adult homozygotes (dn/dn) and five adult heterozygotes (+/dn), matched by weight and sex, were prepared for serial section light microscopy. In the homozygotes, the organ of Corti was totally degenerated basally, gradually improving toward the apex where supporting cells, border cells and pillar cells were present; however, the stria vascularis was dystrophic in the apex. The saccular macula was atrophied or dystrophic in seven of the ten homozygote ears. The homozygotes had only 23% of the number of spiral ganglion cells found in the heterozygotes, but they appeared robust. In six of the ears of each group there was clumping of apical spiral ganglion neurons. In the homozygotes, the volume of Rosenthal's canal was 121%, that of the dorsal nuclei was 90%, and that of the ventral cochlear nuclei was 63% of the comparable volumes in heterozygotes. The globular cells of the homozygote ventral cochlear nucleus were 72% of the size of those of heterozygotes. These quantitative morphological abnormalities of the homozygote spiral ganglion and cochlear nuclei may result from organ of Corti atrophy.

Consultant evaluation of a hospital medication system: analysis of the existing system.

A consultant team's evaluation of a system for distributing and controlling medications in a large teaching hospital is described. Through interviews with key personnel from administration, pharmacy, nursing, and the medical staff, an interdisciplinary research group identified problems in the reliability and response times of the hospital's existing medication system. After assessing staff expectations regarding acceptable standards for medication errors and response times and their attitudes toward proposed changes in the medication system, medication-error rates were determined using a pharmacist-observer method. Observations during 34 five-hour periods on four nursing units were conducted over a 17-day period. Medication-error rates were calculated as the frequency of medication errors during the observation period divided by the total opportunities for error (OE), which were defined as doses ordered plus unauthorized doses given. Response times for processing "now," "stat," and routine orders were also determined using work-sampling methods. The total medication-error rate for the nursing units studied was 9% excluding wrong-time errors; more than a third of doses were given more than 30 minutes before or after their scheduled administration times. Response times for "now" and "stat" orders averaged about 23 minutes, in conformance with the desired standard of 30 minutes. However, processing of routine orders required an average of two hours and seven minutes, much of which was attributed to delays in the messenger service. The basic design of the existing unit dose medication system contributed to problems in the reliability and efficiency of the system.