Position paper: sonic and ultrasonic scalers in periodontics. Research, Science and Therapy Committee of the American Academy of Periodontology.

Ultrasonic and sonic scalers appear to attain similar results as hand instruments for removing plaque, calculus, and endotoxin. Ultrasonic scalers used at medium power seem to produce less root surface damage than hand or sonic scalers. Due to instrument width, furcations may be more accessible using ultrasonic or sonic scalers than manual scalers. It is not clear whether root surface roughness is more or less pronounced following power-driven scalers or manual scalers. It is also unclear if root surface roughness affects long-term wound healing. Periodontal scaling and root planing includes thorough calculus removal, but complete cementum removal should not be a goal of periodontal therapy. Studies have established that endotoxin is weakly adsorbed to the root surface, and can be easily removed with light, overlapping strokes with an ultrasonic scaler. A significant disadvantage of power-driven scalers is the production of contaminated aerosols. Because ultrasonics and sonics produce aerosols, additional care is required to achieve and maintain good infection control when incorporating these instrumentation techniques into dental practice. Preliminary evidence suggests that the addition of certain antimicrobials to the lavage during ultrasonic instrumentation may be of minimal clinical benefit. However, more randomized controlled clinical trials need to be conducted over longer periods of time to better understand the long-term benefits of ultrasonic and sonic debridement.

Photoperiod and gender affect adipose tissue growth and cellularity in juvenile Syrian hamsters.

Adult Syrian hamsters are reproductively active and at their annual body and lipid mass nadirs in long 'summer-like' days (LDs), whereas they are reproductively quiescent and at their annual body and lipid mass peaks in short 'winter-like' days (SDs). Because hamsters are born in the SDs of fall in the wild, the development of the reproductive system of juvenile Syrian hamsters exposed to SDs has been studied in the laboratory, but not the development of body and lipid mass. Therefore, we tested the effect of SDs on white adipose tissue (WAT) growth and cellularity (fat cell number, FCN; fat cell volume, FCV) in 3-15-week-old male and female Syrian hamsters. SDs increased body fat in both genders. This effect was partially independent of the decline in gonadal steroids because gonadal regression was only beginning in males (Week 11) and females (Week 15) when carcass lipid content was significantly increased in males, and nearly so in females. This SD-induced increased adiposity was reflected in few regional differences in WAT growth, and then only in males (increased mesenteric and inguinal WAT masses). SDs increased FCV for all non-gonadal WAT and increased FCN only in retroperitoneal WAT. SDs blunted the LD-induced increased FCV and FCN of parametrial and epididymal WAT, respectively. For nearly all conditions and pads, FCV peaked first, followed by increased FCN, the latter accounting for nearly all WAT growth. These data appear to support the view that adipocyte proliferation is stimulated once a 'critical' FCV is reached.

Expressions of leptin and insulin-like growth factor-I are highly correlated and region-specific in adipose tissue of growing rats.

OBJECTIVE: Anatomically distinct adipose tissue regions differ in their predominant modality of growth (i.e., cellular hypertrophy vs. hyperplasia). We examined site-specific patterns of expression of two genes whose products, leptin and insulin-like growth factor-I (IGF-I), could be involved in mediating differential growth and metabolism of white adipose tissue. We also related these patterns of expression to measures of adipose depot cellularity. RESEARCH METHODS AND PROCEDURES: Male Wistar rats were fed ad libitum and studied from ages 7 weeks to approximately 12 months. Terminal measures of body weights; weights, composition, and cellularity of four white adipose depots; circulating leptin and IGF-I; and adipose depot-specific expression levels of leptin and IGF-I were measured in subsets of rats at 7, 12, 22, 42, and 46 weeks of age. RESULTS: Both leptin and IGF-I mRNAs are quantitatively expressed in a depot-specific manner, in the following order: retroperitoneal approximately equals epididymal > mesenteric > subcutaneous inguinal. Furthermore, there is a marked correlation between the expressions of these hormones in the various regions of adipose tissue of rats during the first year of life. The mechanisms that underlie the parallel expressions of leptin and IGF-I appear to be related to fat-cell volume. DISCUSSION: Because both leptin and IGF-I have been implicated in the regulation of energy homeostasis and are both expressed in adipose tissue, the depot-specific linkage between the two genes suggests interaction at the autocrine level. This interaction may have an important role in determining functional properties particular to individual adipose depots.

Changes in gingival crevicular fluid levels of immunoglobulin A following therapy: association with attachment loss.

BACKGROUND: In previous studies, we demonstrated that increased levels of immunoglobulin A (IgA) in gingival crevicular fluid (GCF) may be "protective", while increased levels of the polymorphonuclear lysosomal enzyme, beta-glucuronidase, in GCF were associated with increased risk of disease activity. In this study, we examined the effect of scaling and root planing (SRP) on the levels of beta-glucuronidase, IgG, and IgA in GCF over a 24-week period and compared these to clinical attachment loss (CAL). METHODS: Twenty-nine patients with periodontal disease were examined for attachment level, probing depth, plaque, and bleeding on probing at 6 sites per tooth. GCF was collected from the mesial aspect of all teeth excluding third molars and analyzed for beta-glucuronidase, IgG, and IgA. After baseline data were collected, each patient received SRP, and GCF was collected again at 2, 4, 6, 8, 12, and 24 weeks post-SRP while clinical data were obtained at 4, 8, 12, and 24 weeks. In addition, we analyzed whether the magnitude of the IgA response to SRP would affect the rate of periodontal disease progression by examining GCF IgA levels at 2 time intervals: 2 to 4 weeks post-SRP and 6 to 12 weeks post-SRP. RESULTS: Seventeen patients (58.6%) exhibited at least 1 site losing > or =2.5 mm of CAL during the 24-week study. Beta-glucuronidase in GCF was significantly decreased at 2 weeks following SRP and then demonstrated a gradual increase throughout the study period. Levels of IgA in GCF significantly increased following SRP, reaching a peak at 6 weeks and then gradually decreasing throughout the study. Furthermore, we found an inverse relationship between GCF IgA levels at 6 to 12 weeks post-SRP and the occurrence of CAL. CONCLUSIONS: These results support the hypothesis that maintenance of high levels of IgA in GCF may be "protective" against periodontal attachment loss. Furthermore, levels of beta-glucuronidase appear to be a more sensitive indicator of gingival inflammation than clinical measures.

Evidence for widespread infection of wild rats with hepatitis E virus in the United States.

Hepatitis E is an important medical pathogen in many developing countries but is rarely reported from the United States, although antibody to hepatitis E virus (anti-HEV) is found in > 1% of U.S. citizens. Zoonotic spread of the virus is suspected. Sera obtained from 239 wild rats trapped in widely separated regions of the United States were tested for anti-HEV. Seventy-seven percent of rats from Maryland, 90% from Hawaii, and 44% from Louisiana were seropositive for anti-HEV. Rats from urban as well as rural areas were seropositive and the prevalence of anti-HEV IgG increased in parallel with the estimated age of the rats, leading to speculation that they might be involved in the puzzling high prevalence of anti-HEV among some U.S. city dwellers. The discovery of a in rats in the United States and the recently reported discovery that HEV is endemic in U.S. swine raise many questions about transmission, reservoirs, and strains of HEV in developed countries.

Black Creek Canal Virus infection in Sigmodon hispidus in southern Florida.

A total of 1,500 small mammals were collected and tested for antibodies cross-reactive to Sin Nombre virus (Hantavirus: Bunyaviridae) at 89 sites in a 1,600 km2 study area of southern Florida. More than 95% of the 123 seropositive animals were cotton rats (Sigmodon hispidus), suggesting infection by Black Creek Canal Virus, although seroreactive Rattus rattus (5 of 294) and Peromyscus gossypinus (1 of 39) also were captured. Crude seroprevalence in S. hispidus was 11%. Seroprevalence increased with body size and was more common in male (18%; n=451) than in female (6%; n=593) cotton rats. Infection within S. hispidus populations was widespread throughout the study area. Prevalence ranged from 0% to 60% at sites where more than five cotton rats were sampled but was not only a function of sample size. Sites with seropositive cotton rats were geographically clustered compared with sites with no seropositive cotton rats. Clustering was not due to the spatial distribution of sites with few animals, season of collection, or sex bias of animals captured at these sites. However, sites with no seropositive animals had an excess of animals in the intermediate size class (60-99 g) and a deficit of the largest and smallest animals. These data suggest that population structure within the habitat mosaic may play a significant role in the spatial distribution of hantavirus infection in local populations of reservoir species.

Qualitative regional differences in adipose tissue growth and cellularity in male Wistar rats fed ad libitum.

Adipose tissue grows primarily by a combination of increases in fat cell volume (hypertrophy) and in fat cell number (hyperplasia), but the regional growth pattern of white adipose tissue depots in animal species and in the human is still unclear. In this study we characterized fully the age-related changes in adipose tissue growth, composition, and cellularity of four fat depots of male Wistar rats that varied in age from 7 wk to 15 mo and in body weight from 178 to 808 g. Body weight and the weight of each of the four adipose depots studied (epididymal, mesenteric, subcutaneous inguinal, and retroperitoneal) increased progressively with age and ad libitum feeding. Comparison of the cellularity of the four adipose depots, however, showed remarkable and significant differences in the pattern of growth within the same animals. The cumulative growth of the two intraabdominal fat depots (mesenteric and epididymal) was due mostly to hypertrophy (increases in cell volume of 83 and 64%, respectively), whereas the growth of the other two depots (retroperitoneal and inguinal) was due predominantly to hyperplasia (increases in cell number of 58- and 65%, respectively). These findings uncover major and unexpected regional differences in the modulation of adipose tissue growth within aging animals fed ad libitum and suggest local, region-specific regulatory controls of this growth.

A simple method to predict cellular density in adipocyte metabolic incubations.

OBJECTIVES: The density of isolated adipocyte suspensions, namely the cellular concentration, influences metabolic results when lipolysis and the pattern of glucose metabolism are studied. It is often difficult to obtain reproducible adipocyte concentrations from experiment to experiment, and investigators usually measure the cell concentration at the end rather than at the initiation of metabolic incubations. METHOD: A simple and rapid method to obtain reliable and predictable adipocyte concentration prior to metabolic incubations is described and validated. The method is based on determination of lipocrit, mean adipocyte diameter (by optical sizing), and calculation of volume, in aliquots of isolated adipocyte suspensions. MAIN OUTCOME MEASURES: Lipocrit, mean adipocyte volume, predicted and observed adipocyte number in isolated cell suspensions. RESULTS: In 15 experiments, adipocyte concentration was accurately predicted within 12-18% of actual concentration. This is in contrast to the four or five-fold differences usually encountered in a series of experiments. CONCLUSION: One can rapidly predict the number of adipocytes present in a given cell suspension with the proposed method, and then correct it to a desired adipocyte concentration at the beginning of metabolic incubations. This method will help to eliminate the confounding effects of variable cell concentrations in in vitro metabolic experiments with isolated adipocytes.

Daylength and body mass affect diet self-selection by Siberian hamsters.

Siberian hamsters exhibit a decrease in peak body mass/fat and caloric intake when they are exposed to short winter-like days (SDs) compared with hamsters exposed to long summer-like days (LDs). We hypothesize that the photoperiod may directly or indirectly mediate alterations in gustatory processing that may account for shifts in the preferences for specific food types and/or macronutrients. Two experiments lasting 14 days each were conducted to: 1) identify photoperiod-related differences in diet selection, and; 2) determine whether these differences were a primary effect of SD exposure or a secondary effect due to SD-induced decreases in body fat/mass. In Experiment 1, two groups of hamsters were exposed to either LDs or SDs and given access to three complex food types [sunflower seeds (SF); rabbit chow (RC); millet seeds (M)]. In addition to their photoperiod-induced decreased body and fat pad mass, and caloric intake, SD-housed hamsters exhibited significant differences in their patterns of diet selection and relative amounts of fat, carbohydrate (COH), and protein eaten compared with LD-housed hamsters. By the end of the experiment, SD-housed hamsters selected a diet higher in COH and protein and lower in fat than that selected by LD-housed hamsters. Because SD-housed hamsters decrease their body mass/fat, this may reflect an adaptive strategy to maintain a leaner body mass. A second experiment was conducted to test whether the diet selection pattern of SD-housed hamsters was due to the SD-induced decrease in body mass/fat. LD-housed hamsters were allowed to feed ad lib (AL group), or were food restricted (FR group) to simulate a SD-induced decrease in body mass. Both groups were then released into the diet self-selection paradigm. FR hamsters reversed their food restriction-induced decrease in body mass and showed concurrent alterations in diet self-selection patterns that were distinct from the SD-induced patterns seen in Experiment 1. Specifically, they showed a persistent hyperphagia and selected a larger proportion of their total calories as M (high COH) and less as SF (high fat) than did AL hamsters during their return to LD body mass levels. However, once LD body mass levels were achieved, they increased their SF intake, and thus fat consumption. Despite these dynamic daily changes, the average selection patterns of both the diet types and macronutrients were not different by the end of the experiment. Therefore, it appears that the SD-induced changes in the selection of food sources (and ultimately, the macronutrient composition of the diet) cannot be solely attributable to the SD-induced decreases in body mass.

Photoperiod and population density interact to affect reproductive and immune function in male prairie voles.

Seasonal breeding of rodents is often associated with changes in adrenal function; altered adrenal function could account, in part, for seasonal changes in immune function and, ultimately, influence seasonal fluctuations in survival. Animals commonly monitor the annual change in photoperiod to ascertain the time of year and to make appropriate seasonal adjustments in physiology and behavior. Several extrinsic factors affect reproductive responsiveness to photoperiod. The interaction between population density and reproductive and adrenal responsiveness to photoperiod was assessed in the present experiment. Adult male prairie voles (Microtus ochrogaster) were maintained individually for 10 wk in long [light:dark (LD) 16:8] or short (LD 8:16) photoperiods in rooms with either high (10.96 animals/m3) or low (0.18 animals/m3) population densities. Regardless of population density, short-day voles regressed the size of their reproductive organs; reproductive organ masses were higher in long-day voles housed in high-density compared with low-density rooms. Paired adrenal masses were reduced in short-day voles, but were unaffected by population density; serum corticosterone concentrations were significantly elevated in short-day compared with long-day animals. In both photoperiods, basal blood corticosterone levels were higher in voles from low-density compared with high-density rooms. Splenic masses were unaffected by day length, but were elevated among high-density animals. Similarly, serum immunoglobulin (IgG) levels were elevated among high-density animals. These results suggest that population density per se, in the absence of behavioral interactions, can affect reproductive size, and possibly function, in long-day conditions, and that prairie voles, which are highly social, exhibit higher corticosterone and lower IgG levels in low compared with high densities. These results may be important in understanding arvicoline population fluctuations, as well as improving animal husbandry practices in the lab.

The relationship of candidiasis to linear gingival erythema in HIV-infected homosexual men and parenteral drug users.

Periodontal status was evaluated in two cohorts participating in a study of the natural history of human immunodeficiency virus (HIV) infection. One cohort consisted of 77 seropositive and 44 seronegative homosexual men, and the other cohort was comprised of 44 seropositive and 39 seronegative parenteral drug users (PDU). No differences were observed between seropositive and seronegative individuals within a cohort in terms of clinical periodontal parameters (percent of sites with > or = 4 mm probing depth, percent of sites exhibiting bleeding on probing, mean oral hygiene index). The PDU displayed more existing periodontal disease than the homosexual men. Periodontal disease in the seropositive individuals in both cohorts was not strictly related to the number of CD4+ lymphocytes. Linear gingival erythema (LGE), defined as an erythematous band of at least 2 mm extending between adjacent papilla, was observed in all 4 groups. Seropositive homosexual men displayed more LGE than seronegative homosexual men (16.6% vs. 11.4%) and seronegative PDU displayed more LGE than seropositive PDU (38.5% vs. 29.5%), but neither difference was significant. LGE tended to be related to reduced numbers of CD4+ lymphocytes, but this relationship did not reach statistical significance. A statistically-significant relationship was found between the presence of intraoral candidiasis and LGE in seropositive homosexual men: 42.9% of these subjects with candidiasis had LGE, while only 12.7% of the subjects without candidiasis had LGE (P < .05). For the seropositive PDU, 35.3% of the individuals with candidiasis had LGE and 25.9% of the subjects without candidiasis displayed LGE, but the difference was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral manifestations of HIV infection in homosexual men and intravenous drug users. Study design and relationship of epidemiologic, clinical, and immunologic parameters to oral lesions.

This article describes the baseline findings from a study designed to compare the oral manifestations of HIV infection in homosexual men and intravenous drug users. Both seropositive and seronegative persons were studied. A standard examination instrument was developed to record indexes of oral disease as well as to record the presence of oral lesions. The two groups differed in terms of education, race, socioeconomic status, employment status, housing, and smoking experience. The prevalence and type of oral lesions differed in the two seropositive groups. In seropositive homosexual men, white lesions on the tongue (28.4%) predominated; whereas for the seropositive intravenous drug users, oral candidiasis (43.0%) and gingival marginal erythema (33.3%) were most often detected. We also observed that seronegative intravenous drug users displayed a greater number of oral lesions than seronegative homosexual men. For seropositive homosexual men, lesion presence was significantly associated with decreased levels of CD4; positive associations were seen with current smoking, antiviral drug use, and antibiotic use, and a negative association was observed with current employment. In contrast, only exposure to antiviral drugs was significantly correlated with lesion presence for seropositive intravenous drug users. This baseline analysis from our longitudinal study suggests clear differences in oral manifestations of HIV infection between seropositive homosexual men and intravenous drug users and between seronegative homosexual men and intravenous drug users. Among other parameters, it is apparent that lifestyle, access to health care, and the condition of the oral cavity before infection influence the development of oral lesions in persons with HIV infection.

Non-reciprocal cross-adaptation of spiking responses of individual olfactory receptor neurons of spiny lobsters: evidence for two excitatory transduction pathways.

Single-unit spiking responses of 72 olfactory receptor neurons (ORNs) in the olfactory organ of the spiny lobster Panulirus argus were recorded extracellularly during presentation of a set of seven odorant stimuli (adenosine-5'-monophosphate, ammonium chloride, betaine, L-cysteine, L-glutamate, D,L-succinate and taurine) and analyzed in order to evaluate the response specificities of single ORNs and the independence of receptor sites. Individual ORNs often had narrow excitatory response spectra, but the most excitatory compound was different from neuron to neuron. These results suggest that these compounds can exert most of their excitatory effects through relatively independent receptor site types. To determine the relative independence of excitatory transduction processes in single ORNs for these stimuli, single-unit spiking responses of these neurons under conditions of self- and cross-adaptation were analyzed. The results demonstrate extensive cross-adaptation between pairs of the seven stimuli. When averaged across all neurons and all cross-adaptation conditions, cross-adaptation resulted in a mean reduction of 81% of the unadapted response. However, there were differences in the degree and pattern of adaptation for different pairs of compounds and for different neuron types (defined by most excitatory or 'best' chemical). For a given neuron type, there were significant levels of non-reciprocal cross-adaptation: neurons cross-adapted more when adapted to their best chemical than when adapted to their non-best chemicals. These results suggest the existence of two excitatory transduction pathways within an olfactory receptor neuron: one pathway activated exclusively by the best chemical and a second pathway activated by a broader spectrum of chemicals.

Short-term microbiological and clinical effects of subgingival irrigation with an antimicrobial mouthrinse.

Fifty chronic adult periodontitis patients completed a 6-week controlled, double-blind, split mouth clinical study to determine the effects of subgingival irrigation with an antimicrobial mouthrinse on periodontal microflora, supragingival plaque, and gingivitis when used as an adjunct to normal oral hygiene. Qualifying subjects had at least four sites, two on each side of the mouth, with probing depths between 4 and 6 mm, which bled on gentle probing. Following baseline examinations, subjects received a half mouth scaling and prophylaxis and full mouth subgingival irrigation with either the antimicrobial mouthrinse or sterile colored water control professionally delivered. Subjects continued irrigation at home once daily for 42 days with their assigned rinse delivered via a subgingival delivery system. All sites in the mouth were scored at baseline and at day 42 for supragingival plaque, bleeding on probing, and redness. For the four selected periodontitis sites, probing depth and attachment level were measured at baseline and on day 42; additionally, supragingival plaque and gingival redness were scored on days 7 and 21. Subgingival plaque samples for microbiological analysis were harvested from the selected periodontal sites at baseline and on days 7, 21, and 42. Microbiologically, irrigation with the antimicrobial mouthrinse resulted in statistically significant reductions compared to control in putative periodontopathogens, including black pigmenting species, which persisted at 42 days. Clinically, subgingival irrigation with the antimicrobial mouthrinse produced a significant reduction in supragingival plaque (P < 0.001), bleeding on probing (P = 0.019), and redness (P = 0.017) compared to the control, whether or not the area irrigated received a prophylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)