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Biomedical subjects

B L Hart

Publications and source records attributed to B L Hart.

At least 73 records · Page 4Linked to original sources
PubMed1990

Antibacterial properties of saliva: role in maternal periparturient grooming and in licking wounds.

Canine saliva was tested for its bactericidal effects against pathogens relevant to the presumed hygienic functions of maternal grooming of the mammary and anogenital areas and licking of wounds. Both female and male saliva were bactericidal against Escherichia coli and Streptococcus canis but only slightly, and nonsignificantly, bactericidal against coagulase positive staphylococcus and Pseudomonas aeruginosa. E. coli is the cause of highly fatal coliform enteritis of neonatal mammals and E. coli and S. canis are the main pathogens implicated in neonatal septicemia of dogs. The bactericidal effects of saliva would facilitate the hygienic function of maternal licking of the mammary and anogenital areas in protecting newborns from these diseases. E. coli and S. canis along with coagulase positive staphylococcus and P. aeruginosa are among the common wound contaminants of dogs. Wound licking, and the application of saliva, would thus reduce wound contamination by E. coli and S. canis. The resistance of staphylococcus to bactericidal effects of saliva may be a factor in the high frequency (46 percent) with which coagulase positive staphylococcus was isolated from wounds compared with much lower frequency (9-17 percent) with which E. coli and S. canis were isolated.

Animals↗
PubMed1990

Behavioral adaptations to pathogens and parasites: five strategies.

The ever present threat of viral, bacterial, protozoan and metazoan parasites in the environment of wild animals is viewed as responsible for the natural selection of a variety of behavioral patterns that enable animals to survive and reproduce in this type of environment. Several lines of research, some quite recent, point to five behavioral strategies that vertebrates utilize to increase their personal or inclusive fitness in the face of parasites (broadly defined to include pathogens). These are: 1) avoidance of parasites; 2) controlled exposure to parasites to potentiate the immune system; 3) behavior of sick animals including anorexia and depression to overcome systemic febrile infections; 4) helping sick animals; 5) sexual selection for mating partners with the genetic endowment for resistance to parasites. The point is made that to consider a behavioral pattern as having evolved to serve a parasite control function the parasite or causative agent should be shown to adversely impact the animal's fitness and the behavior in question must be shown to help animals, or their offspring or group mates, in combating their exposure, or reducing their vulnerability, to the parasite.

Adaptation, Psychological↗
PubMed1989

Age and race related changes in mammographic parenchymal patterns.

The relationship between breast parenchymal patterns and age was examined in a nonselected, nonreferred group. The three major racial-ethnic subgroups represented have markedly different incidences of breast cancer, with Anglos (nonHispanic caucasians), Hispanics, and American Indians having higher to lower incidence rates of breast cancer, respectively. Mammograms were performed in 519 victims of nonhospital, nonnatural or unexplained deaths in New Mexico. The percentage of dense breast patterns (DY + P2) decreased with age for all groups. American Indian women showed a much earlier shift to a lower density parenchymal pattern than Anglo or Hispanic women. At older ages Indian women continued to have a slightly lower percentage of dense breast patterns than the other groups. The changes in breast parenchymal pattern with age and ethnic groups may reflect factors related to risk of breast cancer.

Adolescent↗
PubMed1989

Radon: is it a problem?

Radon gas is a major source of radiation exposure to the general public. Radon-222 is a product of uranium-238, present in varying concentrations in all soils. Radon enters buildings from soil, water, natural gas, and building materials. Its short-lived breakdown products, termed "radon daughters," include alpha-emitting solids that can deposit in the lungs. Firm evidence links lung cancer risk in miners with high exposure to radon daughters. The amount of risk associated with the much lower but chronic doses received in buildings is difficult to establish. By some extrapolations, radon daughters may be responsible for a significant number of lung cancer deaths. The existence or extent of synergism with smoking is unresolved. Local conditions can cause high levels of radon in some buildings, and measures that reduce indoor radon are of potential value.

Bismuth↗
PubMed1989

Pulmonary needle embolism from intravenous drug abuse.

Although the embolization of catheters and other foreign bodies in blood vessels is a well-known happening, needle embolization has rarely been reported. We describe here an instance in which a hypodermic needle broke in a man's skin during cocaine injection. The needle fragment was observed to migrate within a short time to the periphery of the left lung. The patient did not develop complications. The limited literature available indicates that such peripheral embolization usually follows a benign course.

Adult↗
PubMed1988

Alteration in vomeronasal system anatomy in alcelaphine antelopes: correlation with alteration in chemosensory investigation.

Ruminants typically have an incisive papilla and incisive ducts located on the hard palate just behind the dental pad which are involved in transferring fluid-borne stimulus material from the oral cavity to the vomeronasal organs (VNOs) during flehmen. This behavior in males is presumably involved in the detection of chemosensory cues in female urine which indicate sexual status. Two species of alcelaphine antelopes, topi and Coke's hartebeest, were found to lack the incisive papilla and incisive ducts constituting the oral connection to the VNOs. This distinctive anatomical feature is complemented in these species not only by lack of flehmen behavior, but also a de-emphasis on chemosensory interest in female urine during sexual encounters. The common wildebeest, which is also an alcelaphine antelope, lacks the incisive papilla, but has small incisive ducts. Wildebeest males do perform flehmen to urine from females. However, during flehmen in the wildebeest, intermittent nostril licking apparently delivers the stimulus material to the VNOs via the nasal route, possibly compensating for reduced oral access to the VNOs. These observations on alcelaphine antelopes would appear to represent a unique feature among the world's ruminants.

Animals↗
PubMed1988

Biological basis of the behavior of sick animals.

The most commonly recognized behavioral patterns of animals and people at the onset of febrile infectious diseases are lethargy, depression, anorexia, and reduction in grooming. Findings from recent lines of research are reviewed to formulate the perspective that the behavior of sick animals and people is not a maladaptive response or the effect of debilitation, but rather an organized, evolved behavioral strategy to facilitate the role of fever in combating viral and bacterial infections. The sick individual is viewed as being at a life or death juncture and its behavior is an all-out effort to overcome the disease.

Animal Diseases↗
PubMed1987

Stimulus and hormonal determinants of flehmen behavior in cats.

Felids are the main group of animals, other than ungulates, that display flehmen behavior during sociosexual interactions. In ungulates the behavior is evoked most readily by olfactory investigation of urine and vaginal secretions, and is believed to be involved in the transport of fluid-borne chemical stimuli, such as sex pheromones, from the oral cavity to the vomeronasal organ. In this study of cats flehmen was virtually always preceded by nasooral contact with the stimulus material, supporting the notion that flehmen in this species is also involved in the transport of fluid-borne stimuli. As in ungulates, flehmen in cats during heterosexual encounters was found to be displayed by males only. However, the sexual dimorphism was situation specific. In exploring a urine-marked room without another cat present, females also performed flehmen, albeit less frequently than males, and when urine was applied to the nasooral surface, flehmen was evoked equally reliably in females and males. Administration of testosterone propionate to spayed female cats paired with estrogen-treated females markedly increased their tendency to genitally inspect the female partner and subsequently perform flehmen. Thus the sexually dimorphic attributes of flehmen behavior are not only stimulus dependent, but also influenced by concurrent hormone stimulation.

Animals↗
PubMed1987

Postcopulatory genital grooming in male rats: prevention of sexually transmitted infections.

Prevention of postcopulatory genital grooming in male rats increased the likelihood that they would be genitally infected with a marker microorganism (Staphylococcus aureus) inoculated previously into the vagina of female rats. Male as well as female rat saliva was found to have very minimal bactericidal effects on the marker organism indicating that physical washing during postcopulatory grooming can prevent the transmission of infectious organisms. Saliva of both male and female rats, however, was found to have bactericidal effects on 2 murine pathogens (Pasteurella pneumotropica and Mycoplasma pulmonis) that infect the genitalia of males and females, revealing that the physical washing effect can be enhanced by specific antibacterial properties of saliva for some reputed genital pathogens.

Animals↗
PubMed1987

Behavior of sick animals.

The behavior of the sick animal is not necessarily a result of physical debilitation; it can be viewed as part of a highly organized adaptive strategy that is at times critical to survival if the animal were living in the wild state. Domestic ruminants appear to have retained this behavioral mode when they are sick. This article brings together several lines of current research about depression, appetite control, and the role of fever in facilitating an animal's ability to combat viral and bacterial infections.

Animals↗
PubMed1987

Roles of the olfactory and vomeronasal systems in behavior.

The chemosensory experiences of farm animals involve a stimulus world that we are incapable of appreciating through our own limited olfactory system and nonexistent vomeronasal system. It is obvious that to domestic ruminants as well as their wild counterparts these systems are an important element in day-to-day activities and in social encounters. As we come to learn more about the role of chemosensory analysis by both the olfactory system and the vomeronasal system, we will eventually have the opportunity to utilize such information more effectively to manage the reproduction, growth, and welfare of our domestic livestock species.

Animals↗
PubMed1987

Role of oxygen in the production of human decompression sickness.

In the calculation of decompression schedules, it is commonly assumed that only the inert gas needs to be considered; all inspired O2 is ignored. Animal experiments have shown that high O2 can increase risk of serious decompression sickness (DCS). A trial was performed to assess the relative risks of O2 and N2 in human no-decompression dives. Controlled dives (477) of 30- to 240-min duration were performed with subjects breathing mixtures with low (0.21-0.38 ATA) or high (1.0-1.5 ATA) Po2. Depths were chosen by a sequential dose-response format. Only 11 cases of DCS and 18 cases of marginal symptoms were recorded despite exceeding the presently accepted no-decompression limits by greater than 20%. Analysis by maximum likelihood showed a shallow dose-response curve for increasing depth. O2 was estimated to have zero influence on DCS risk, although data variability still allows a slight chance that O2 could be 40% as effective as N2 in producing a risk of DCS. Consideration of only inert gases is thus justified in calculating human decompression tables.

Decompression Sickness↗
PubMed1987

Improved external beam radiotherapy for the treatment of retinoblastoma.

An applicator attached to a 6 MV linear accelerator has been adapted to produce a well defined beam for the treatment of retinoblastoma. By using a contact lens as the reference point on the patient's cornea, the beam edge is aligned to just behind the posterior margin of the crystalline lens, thus sparing the anterior chamber and lens from the radiation field. In addition to basic dosimetric measurements made using an ionisation chamber and film densitometry to quantify the output and dose distribution from the applicator, extensive use was made of thermoluminescent dosemeters and a tissue-equivalent anthropomorphic head phantom. This was designed for detailed dosimetry on the eye and was used to confirm the correct positioning and reproducibility of the clinical set-up. We present data that corroborate and extend the dosimetric analyses documented in an earlier Dutch publication. In addition to the improved dosimetric analysis, other advantages include patient immobilisation, anaesthetic procedure and finer couch control as well as a recommendation on the dose prescription.

Eye Neoplasms↗
PubMed1986

Medial preoptic-anterior hypothalamic lesions and sociosexual behavior of male goats.

With the aid of x-ray ventriculography, lesions were placed in the medial preoptic-anterior hypothalamic (MP-AH) area of 5 adult male pygmy goats. The lesions resulted in a marked decrement in ejaculatory responses, as they have in previous studies on rats, cats, dogs and rhesus monkeys. The results illustrate the apparent universal effects of MP-AH lesions on copulatory behavior in mammalian species. Male sex-typical non-courtship responses of flehmen, self-enurination and penis licking were not altered by the MP-AH lesions. Since the non-courtship responses are displayed most frequently when male goats are sexually aroused, the results point to a specific effect of the lesions in disturbing a male's copulating performance while sparing other expressions of sexual arousal.

Animals↗
PubMed1986

Medial preoptic-anterior hypothalamic lesions in prepubertal male cats: effects on juvenile and adult sociosexual behaviors.

Bilateral lesions of the medial preoptic-anterior hypothalamic (MP-AH) area were made in prepubertal male cats at 6-8 weeks of age. All subjects were subsequently reared in groups containing male and female peers, until the last phase of the juvenile period when an adult estrous female was inserted in these social groups. In spite of such optimal conditions for the practice of sociosexual behaviors during development, no sparing of adult male copulatory behavior was observed in these MP-AH animals during testing in adulthood. This finding, while consistent with earlier work on dogs, contrasts with the results obtained in prepubertally lesioned rats. Urine spraying, another sexually dimorphic behavior which is eliminated by MP-AH lesions in adult cats, was spared by prepubertal lesion placement. Heterotypical sexual behavior was not enhanced by prepubertal MP-AH lesion placement, as it is with postpubertal placement. In the present study, therefore, different behavioral systems influenced by the MP-AH area showed varying degrees of plasticity. As found in dogs, prepubertal MP-AH lesions enhanced and accelerated testosterone secretion in cats.

Animals↗