Horizontal transmission of mutans streptococci in children.

It has not been established whether transmission of mutans streptococci occurs between unrelated children older than 4 years of age. The aim of the study was to investigate the possible transmission of mutans streptococci genotypes from child to child in kindergarten. We studied 96 children (ages 5-6 yrs) in three San Francisco Bay Area public schools. Mutans streptococci colonies from each child were isolated from selective culture on Mitis Salivarius Sucrose Bacitracin agar. We used arbitrary primed polymerase chain reactions to determine the mutans streptococci genotypes. Two children (not siblings) in each of the three schools (6%) shared an identical amplitype of S. mutans, unique to each pair. The 19 S. sobrinus amplitypes were found in 12 children, and all were unique to each child. The presence of matching genotypes of S. mutans demonstrates horizontal transmission of this species between unrelated children aged 5-6 years.

Role of area postrema in control of torpor in Siberian hamsters.

Siberian hamsters undergo torpor during the short days of winter and in response to glucoprivation or food restriction. We tested whether the area postrema and the adjacent nucleus of the solitary tract (hereafter the AP), which monitor metabolic fuel availability, also control the onset of torpor. Siberian hamsters that had manifested torpor spontaneously or had entered torpor in response to 2-deoxy-D-glucose (2-DG) treatment were subjected to area postrema ablations (APx). Hamsters continued to display torpor postoperatively; most features of torpor were unaffected by APx. The AP is not necessary for expression of torpor elicited by short day lengths or metabolic challenge. In contrast, decreases in food intake manifested by hamsters treated with 2-DG were counteracted by APx. In Siberian hamsters, the AP appears to mediate effects of 2-DG on food intake but not torpor.

DNAPROBE, a computer program which generates oligonucleotide probes from protein alignments.

We describe a program to assist in designing oligonucleotide probes on the basis of protein alignments and the codon usage of the target organism. If necessary, the input sequences can be weighted to neutralise the effect of closely similar sequences or to bias the output in favour of a particular taxon.

Photoperiod modulates torpor and food intake in Siberian hamsters challenged with metabolic inhibitors.

Siberian hamsters, Phodopus sungorus, exposed to a short photoperiod (SP) were challenged with 2-deoxy-D-glucose (2DG), which disrupts glycolysis and induces torpor in animals maintained in long photoperiods (LP), or mercaptoacetate (MA), which disrupts fatty acid oxidation. SP decreased rather than facilitated the induction of torpor by 2DG; decreased torpor in response to 2DG coincided with onset of spontaneous torpor in SP hamsters. In contrast, MA induced hypothermia in hamsters kept in SP but not LP, but did not induce full torpor. We conclude that short day lengths do not induce spontaneous torpor by increasing responsiveness to glucose availability; instead, responsiveness to glucoprivation is, if anything, blunted in SP. The occurrence of spontaneous torpor may be unrelated to concurrent metabolic fuel availability. Although 2DG and MA had different effects on thermoregulation in short vs. long day lengths, each treatment decreased 24-h food intake in hamsters in both photoperiods.

Torpor in lactating Siberian hamsters subjected to glucoprivation.

Daily torpor has never been reported for any rodent species during lactation. To test whether torpor and lactation are incompatible processes, we administered 2-deoxy-D-glucose (2-DG), a glucose analog that interferes with cellular glycolysis, to Siberian hamsters during the 2nd wk postpartum. 2-DG (2,500 mg/kg of body mass) induced torpor in lactating as well as nonlactating females. Although depth of torpor did not differ between groups, duration of torpor tended to be shorter in lactating animals. Evidence of new milk bands suggests that pups were able to obtain milk from torpid dams. By contrast, dams subjected either to a combination of brief food deprivation and subsequent food restriction or just food restriction failed to display torpor, but instead cannibalized one or more pups. We conclude that torpor is possible during lactation; whether lactating dams in nature become torpid in response to energy shortages or cannibalize or abandon one or more of their offspring remains unknown.

Metabolic fuel availability influences thermoregulation in deer mice (Peromyscus maniculatus).

Body temperature (Tb) was monitored telemetrically in adult deer mice kept in an environmental chamber at low ambient temperature (Ta = 15 degrees C). Mice were challenged with various doses of 2-deoxy-D-glucose (2DG, a glycolysis inhibitor) or mercaptoacetate (MA, a fatty acid oxidation inhibitor) or a combination of the two drugs. A preliminary study suggested that higher doses of 2DG and MA, either individually or together, tended to produce a transient decrease in Tb. In the main experiment, either 2DG or MA or the two drugs together was sufficient to induce a significant, temporary hypothermia. In neither experiment, however, did any treatment affect 24-h food intake or induce daily torpor. The latter outcome contrasts with Siberian hamsters, in which torpor is readily triggered by similar 2DG treatments. Apparently, glucoprivation and lipoprivation resulting from 2DG and MA treatments, respectively, sufficient to produce significant hypothermia, are inadequate to instigate torpor in Peromyscus.

Endocrine basis for two types of individual differences in lordosis reflex intensity.

We have identified individual differences in two independent types of lordosis reflex intensity. Overall lordosis reflex intensity, averaged across 9.4 +/- 0.99 days (range = 1-18 days), differs among cycling individuals and is a biomarker for the rate and pattern of reproductive aging. Although estrogen is necessary to permit lordosis reflex responding and manifests individual differences throughout the estrous cycle, it was individual differences in progesterone that correlated negatively with the individual variation in overall lordosis reflex intensity; females with intense overall lordosis reflexes had low progesterone throughout the estrous cycle. Independent of their overall reflex intensity, females also displayed individual variation in lordosis reflex intensity on proestrus. Among females that still maintained a cyclic lordosis reflex, those with intense lordosis reflexes on proestrus had high levels of luteinizing hormone (LH) at lights out. Among females that displayed intense lordosis reflexes throughout the estrous cycle (i.e., had entered constant lordosis), those with intense proestrous lordosis reflexes had low levels of LH at lights out on proestrus. Females who had entered constant lordosis tended to have lower overall progesterone than females who still maintained cyclic patterns of lordosis. Thus, constant lordosis was identified as an important component of the changes of reproductive aging.

Protection afforded greenhouse pesticide applicators by coveralls: a field test.

Applicators of chlorpyrifos, fluvalinate, and ethazol to ornamentals in a Florida greenhouse were monitored for exposure in a replicated experiment. Pesticide exposure was assessed, using pads placed inside and outside three types of protective coveralls. Potential total body accumulation rates, excluding hands, as calculated from outside pads, depended strongly upon the rate at which pesticide left the spray nozzles. When these total body rates were normalized for spray rate, the mean results, in mg-deposited/kg-sprayed, ranged from 166 to 1126, depending upon the compound applied and the application device. Overall penetration of pesticide through a disposable synthetic coverall was 3 +/- 1% for chlorpyrifos and fluvalinate, and 35 +/- 9% for ethazol. Penetration through a reusable treated twill coverall was 19 +/- 6% for chlorpyrifos, 22 +/- 13% for fluvalinate, and 38 +/- 5% for ethazol.

Field evaluation of coverall fabrics: heat stress and pesticide penetration.

The effect of wearing coveralls on the heat stress of ten professional airblast applicators of ethion to Florida citrus were studied. During the period June 21, 1988 to August 9, 1988, applicators wore protective clothing of the same design, but made of seven different fabrics. Heat stress was evaluated by measuring the mean skin temperature, oral temperature, and heart rate of pesticide applicators. Subjects also provided subjective evaluations. Seven environmental variables were also monitored. Although each fabric was replicated an average of 17 times for thermal comfort and an average of 23 times for penetration, statistical tests for differences among fabrics were usually not significant at the p less than 0.05 level. Observed differences among suits were statistically significant at p = 0.27 for the heat stress experiment, and extended over the range p = 0.003-0.500 for the penetration experiment. Lighter weight, untreated fabrics marginally ameliorated heat stress under severe environmental conditions, but they allowed more pesticide penetration.

Protection afforded citrus pesticide applicators by coveralls.

Four airblast applicators of the pesticides dicofol and ethion to Florida citrus were monitored for pesticide exposure with pads placed inside and outside two types of protective coveralls. Hand exposure was not assessed. Pesticide accumulated uniformly over the coveralls' outer surface at a mean rate of 55 ±6 mg/hr. The penetration of ethion through a reusable treated twill suit was 8 ±2% and through a disposable synthetic suit was 6 ±4%; corresponding values for dicofol were 4 ±1% and 1 ±0%, respectively. While these four penetration values could not be separated statistically at p<0.05, it isprobable (p<0.20) that ethion was the better penetrator, and the disposable synthetic suit the better protector against dicofol.

Pesticide exposure to greenhouse handgunners.

The exposure of pesticide applicators in a commercial greenhouse facility was assessed. Data were collected from four handgunners who applied fluvalinate (insecticide), chlorpyrifos (insecticide), ethazol (fungicide), and dicofol (miticide). Potential exposure was measured with exposure pads placed outside all clothing of the applicator. Handwashes and air samples were also collected, as were pre- and post-exposure tank mixture samples. Pesticide penetration was measured with exposure pads placed inside protective clothing. When all exposure assessments were normalized for spray rate, it was determined that applicators were at significantly greater potential dermal risk (excluding hands) from fluvalinate. The normalized air samples showed significantly more exposure to the applicator from ethazol. Exposure to outside pads was primarily (84%) to the legs of the applicators. Ethazol penetrated Tyvek coveralls more readily than the other compounds. Tank mixture analyses suggested that the wettable powder formulations were not well-mixed.