A community-based, interagency approach by dietitians to provide meals, medical nutrition therapy, and education to clients with HIV/AIDS.

Dietitians have the opportunity to be leaders in providing medical nutrition therapy and home-delivered meals for people with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) in the community setting. Four community agencies developed the Visiting Nurse Service HIV/Home Delivered Meals Program. Fifty clients with the diagnosis of HIV and/or AIDS were served for a 6-month period. The program provided convenient, energy-enhanced nutritious meals. Participants received daily hot and cold, energy- and protein-enhanced home-delivered meals; weekly high-energy, high-protein, shelf-stable Snack Packs; a Medical Nutritional Supplement Sampler Pack; and two home visits from dietitians. Different diet options were available. Dietitians completed 47 initial nutrition assessment and food safety education visits 1 to 2 weeks after meal delivery began, and 35 participants received follow-up nutrition counseling visits 4 to 8 weeks later. Participant data (including weights) were self-reported. Dietitians reported that 13 of 35 participants gained weight (mean = 6 lb), 11 of 35 remained the same weight, and 11 of 35 lost weight (mean = 5 lb). Initially, 14 of 35 participants were considered to be "doing well"; this improved to 19 of 35 participants 1 to 2 months later. Snack Packs were effective means to help participants meet some of their increased nutrient needs. The Medical Nutritional Supplement Sampler Pack was effective in familiarizing each participant with available products. Medical nutrition therapy by registered dietitians helped most participants improve their food consumption.

Sexual preference and altruism.

Several hypothesis have been offered to explain homosexuality. This study tests the prediction of the sociobiological model that male homosexuals should be more altruistic than heterosexuals. Subjects were dichotomized into homosexual (N = 76) and heterosexual (N = 51) groups on the basis of self-reported sexual feelings and behaviors. Both groups provided demographic information and completed Hogan's Scale. As predicted, the homosexuals were found to score significantly higher on the empathy assessment. Given the strong association between empathy and altruism, the sociobiological model was supported.

Vaginal secretions increase the likelihood of intermale aggression in Syrian hamsters.

Although sexually receptive female hamsters prefer dominant males as mating partners, it is not clear what role the female might play facilitating aggressive interactions among males that would lead to the establishment of a status relationship. The ability of vaginal odors to stimulate male aggression was examined by paring randomly chosen males in a neutral arena with vaginal odors either present or absent. Males exhibited significantly more aggression when tested in the scented arena. Vaginal odors are efficient broadcast signals serving to space females, attract males, and to stimulate aggressive interactions among the males while inhibiting aggression towards the female.

The influence of a male's dominance status on female choice in Syrian hamsters.

This study evaluated the importance of dominance status on mate selection in Syrian hamsters. In one experiment, sexually receptive females were allowed to choose between tethered males which differed in status. The choice was consistently in favor of the dominant male. The female spent more time in lordosis in the presence of the dominant male. The dominant also obtained a significantly greater number of intromissions. A second experiment investigated whether prior familiarization was essential to permit a female to express mating preferences in a situation where she was free to interact with three males. Again, the dominants were most often preferred and obtained greater sexual access to the female. Prior familiarization or extensive contact with the males was not necessary to support the female's selection of the dominant as a mating partner. The choice occurred quickly, generally within 5 min after contacting the males. Although females did mate with the subordinates, this typically occurred late in the tests. The significance of these data with respect to mate choice and probable paternity effects are discussed.

A role for the hamster's flank gland in heterosexual communication.

It is commonly assumed that the male hamsters' flank glands subserve an agonistic role with other males as the intended recipients of the olfactory message. Because of little evidence to support such a relationship, two studies investigated whether females might selectively respond to male flank odors. In a free choice situation females spent more time in proximity with glandular rubbings obtained from intact males than those obtained from castrates or a clean control. Moreover, these sexually receptive females remained longer near odors from familiar as opposed to novel males. The second experiment demonstrated that receptive females spent more time in proximity with flank odors of dominant males as opposed to their subordinate partners or to a clean control. Females can use flank gland odors to discriminate among males as a function of their hormonal state, familiarity and dominance. If this occurs in the wild, such odors could provide cues which would facilitate intersexual selection.

A lack of avoidance of flank gland secretions by male Syrian hamsters.

It is commonly assumed that sexually dimorphic cutaneous glands are important in supporting inter-male aggression in rodents. Such an intimidation role has been hypothesized as the function of the hamsters' flank gland. Two experiments failed to find avoidance of male flank odors. In one, subordinate males entered and spent comparable amounts of time in clean areas and areas scented with the dominant's flank secretion. In the other study, males were found to respond differentially to flank odors obtained from the subject, a familiar and a novel male. Although the males seemed to have habituated to the odor of the familiar male, there was no suggestion of avoidance of any of these odors. It may be that the males' flank odor is relevant not to other males but to females.

Responses to salivary olfactants in relation to dominance of the degu (Octodon degus).

Large amounts of head sniffing and grooming have been associated with social dominance in the degu. This study examined whether salivary olfactants act as cues which could potentially mediate social dominance in 4 male and 8 female adults. Using salivary samples taken from the buccal cavities of partners of predetermined status, no preferences for dominant or submissive stimuli were evident. Comparison of work with the degu and that with other species was made.

Female discrimination of male dominance by urine odor cues in hamsters.

Female hamsters have been found to differentially respond to the odors of dominant as opposed to subordinate males. This study reexamined these responses in an olfactometer allowing the females to choose between urinary odors obtained from males differing in dominance status and clean air source. The behavior of the estrous females was consistent with previous research which indicated that such females exhibit a preference for stimuli obtained from dominant males. Contrary to previous findings in a two-choice apparatus, diestrous females failed to prefer the odors of subordinates. These females spent significantly more time in the area infused with unscented air. These data emphasize the importance of odor cues as they relate to male attractivity and possibly mate choice. They also underscore the need to allow animals to avoid conspecific odors in order to reduce the possibility of forcing animals into an unrealistic choice situation.

Sex differences during initial social contact in the degu (Octodon degus ).

The degu is a hystricomorph rodent endemic to South America. Initial social interactions between like-sexed pairs in a neutral area were found to be heavily influenced by sex-class membership. Twelve of fifteen behavioral categories were differentiated on the basis of sex-class. Descriptive factor loadings indicated that social contact was facilitated in females via olfactory investigation. In males, social avoidance or spacing behaviors were characteristic. In both sexes, scent marking and olfactory investigation was prevalent. These data serve to expand our knowledge of the behavior of this social rodent, and to document the sexual dimorphism evident in early social activities.

The failure to demonstrate avoidance of ventral gland odors in male gerbils (Meriones unguiculatus).

The gerbil's ventral gland secretion has been assumed to play a role in territorial defense. The odor of this secretion should be avoided by males which have recently lost a dominance contest to a male which deposited the odor mark. In two experiments, male gerbils were randomly paired and dichotomized on the basis of dominance status. Twenty-four hours later, they were presented either with the odor of the dominant member of the pair in an otherwise clean open-field, or with the odors of the dominant, a novel male, the subject or an unscented area. There was no indication that the animals differentiated the dominants' odors from the others. In neither case was an odor avoided. Areas containing the odor of conspecifics were marked less frequently than the clean area. These data indicate that conspecific odors were detected, but there was no evidence of a differential response to any of the odors employed.

Responses to conspecifics' urine by the degu (Octodon degus).

In nature the degu has been observed to deposit and to investigate scents. This study employed a captive group of these animals to investigate their responses to conspecific urinary marks in a neutral arena. Both sex classes served as subjects. They were presented with urine obtained from males, from females and a saline control. The females were found to be more active in responding. On the basis of sniffing frequency, they exhibited greater discriminative abilities than did the males. The urine from female donors was sniffed more frequently by all subjects. The frequency of approaching a mark and the time spent in the vicinity of a stimulus are interpreted as being investigatory responses. It seems that the marks deposited by females have a greater salience and that females are more sensitive to olfactory stimuli.

Breeding history and olfactory discrimination in the Syrian hamster.

The ability of outbred female Syrian hamsters to differentially respond to urine samples obtained from either inbred or outbred Syrian males was examined. The odors obtained from the males were introduced into a Y-maze olfactometer. On the basis of time spent in proximity to the stimuli, estrous females evidenced a preference for the urine of the outbred males. The same females when diestrus exhibited no apparent preferences. It is possible that the ability of females to make such subtle discriminations may impact on mate selection leading to positive assortment.

Preferences for salivary odor cues by female hamsters.

There is a growing body of data which indicates that saliva may function as a chemosignal in mammals. The salience of this cue in hamsters is investigated. Twelve females were tested in a four-choice olfactorium to determine whether the subjects could differentiate and demonstrate a preference for salivary cues as a function of the dominance status of the stimulus donors and the subjects estrous state. Clear differences in responding were found for estrous as opposed to diestrous females. Estrous females detected and exhibited a preference for male stimuli on the basis of entry and approach measures. Subjects were also found to exhibit sniffing preferences for male odors and possible an avoidance of female odors relative to the saline control. Estrous females appeared to be unable to distinguish between dominant and subordinate males.

The ability of females to predict male status via urinary odors.

In an earlier study, estrous female hamsters were found to prefer the urinary odors of dominant males. This study investigated whether estrous females would exhibit preferential responding to randomly chosen, socially naive males before dominance testing occurred. Estrous females were indeed found to exhibit such preferences. Such discriminative abilities are discussed with reference to adaptive mating strategies for females.