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Biomedical subjects

G E Robinson

Publications and source records attributed to G E Robinson.

At least 19 recordsLinked to original sources
PubMed1995

Effects of experience and juvenile hormone on the organization of the mushroom bodies of honey bees.

There is an age-related division of labor in the honey bee colony that is regulated by juvenile hormone. After completing metamorphosis, young workers have low titers of juvenile hormone and spend the first several weeks of their adult lives performing tasks within the hive. Older workers, approximately 3 weeks of age, have high titers of juvenile hormone and forage outside the hive for nectar and pollen. We have previously reported that changes in the volume of the mushroom bodies of the honey bee brain are temporally associated with the performance of foraging. The neuropil of the mushroom bodies is increased in volume, whereas the volume occupied by the somata of the Kenyon cells is significantly decreased in foragers relative to younger workers. To study the effect of flight experience and juvenile hormone on these changes within the mushroom bodies, young worker bees were treated with the juvenile hormone analog methoprene but a subset was prevented from foraging (big back bees). Stereological volume estimates revealed that, regardless of foraging experience, bees treated with methoprene had a significantly larger volume of neuropil in the mushroom bodies and a significantly smaller Kenyon cell somal region volume than did 1-day-old bees. The bees treated with methoprene did not differ on these volume estimates from untreated foragers (presumed to have high endogenous levels of juvenile hormone) of the same age sampled from the same colony. Bees prevented from flying and foraging nonetheless received visual stimulation as they gathered at the hive entrance. These results, coupled with a subregional analysis of the neuropil, suggest a potentially important role of visual stimulation, possibly interacting with juvenile hormone, as an organizer of the mushroom bodies. In an independent study, the brains of worker bees in which the transition to foraging was delayed (overaged nurse bees) were also studied. The mushroom bodies of overaged nurse bees had a Kenyon cell somal region volume typical of normal aged nurse bees. However, they displayed a significantly expanded neuropil relative to normal aged nurse bees. Analysis of the big back bees demonstrates that certain aspects of adult brain plasticity associated with foraging can be displayed by worker bees treated with methoprene independent of foraging experience. Analysis of the overaged nurse bees suggests that the post-metamorphic expansion of the neuropil of the mushroom bodies of worker honey bees is not a result of foraging experience.

Aging↗
PubMed1995

Volume changes in the mushroom bodies of adult honey bee queens.

The volume of the mushroom bodies of the brains of honey bee queens (Apis mellifera) was estimated using the method of Cavalieri. Tissue sampled was obtained from queens in five different behavioral and reproductive states: 1-day-old virgin queens, 14-day-old virgin queens, 14-day-old instrumentally inseminated queens, 9- to 13-day old naturally mated queens, and 5-month-old naturally mated queens. There were significant volume changes within the mushroom bodies during the first 2 weeks of adult life. The volume occupied by the somata of the intrinsic neuronal population (Kenyon cells) of the mushroom bodies decreased by approximately 30% and the volume of the neuropil of the mushroom bodies increased between 25 and 50%. These volume changes are strikingly similar to those previously reported to occur for worker honey bees switching from hive activities to foraging (Withers, Fahrbach, & Robinson, 1993). However, in this study they were found even in queens that had no flight experience. In addition, queens exhibiting these volume changes were found to have low blood levels of juvenile hormone, while previous studies have shown that foraging worker honey bees have high hormone levels. These results suggest that some aspect of behavioral development common to both the queen and the worker castes is fundamental to protocerebral volume changes early in adulthood in honey bees. If juvenile hormone regulates this process, results from queens suggest that it may play an organizational role.

Animals↗
PubMed1995

Seasonal changes in juvenile hormone titers and rates of biosynthesis in honey bees.

Honey bee colonies can respond to changing environmental conditions by showing plasticity in age related division of labor, and these responses are associated with changes in juvenile hormone. The shift from nest tasks to foraging has been especially well characterized; foraging is associated with high juvenile hormone titers and high rates of juvenile hormone biosynthesis, and can be induced prematurely in young bees by juvenile hormone treatment or by a shortage of foragers. However, very few studies have been conducted that study plasticity in division of labor under naturally occurring changes in the environment. To gain further insight into how the environment and juvenile hormone influence foraging behavior, we measured juvenile hormone titers and rates of biosynthesis in workers during times of the year when colony activity in temperature climates is reduced: late fall, winter, and early spring. Juvenile hormone titers and rates of biosynthesis decreased in foragers in the fall as foraging diminished and bees became less active. This demonstration of a natural drop in juvenile hormone confirms and extends previous findings when bees were experimentally induced to revert from foraging to within-hive tasks. In addition, endocrine changes in foragers in the fall are part of a larger seasonally related phenomenon in which juvenile hormone levels in younger, pre-foraging bees also decline in the fall and then increase the following spring as colony activity increases. The seasonal decline in juvenile hormone in foragers was mimicked in summer by placing a honey bee colony in a cold room for 8 days. This suggests that seasonal changes in juvenile hormone are not related to photoperiod changes, but rather to changes in temperature and/or colony social structure that in turn influence endocrine and behavioral development. We also found that active foragers in the late winter and early spring had lower juvenile hormone levels than active foragers in late spring. In light of recent findings of a possible link between juvenile hormone and neuroanatomical plasticity in the bee brain, these results suggest that bees can forage with low juvenile hormone, after previous exposure to some threshold level of juvenile hormone leads to changes in brain structure.

Analysis of Variance↗
PubMed1992

Honeybee colony integration: worker-worker interactions mediate hormonally regulated plasticity in division of labor.

Adult workers in honeybee (Apis mellifera) colonies exhibit plasticity in hormonally regulated, age-based division of labor by altering their pattern of behavioral development in response to changes in colony conditions. One form of this plasticity is precocious development: levels of juvenile hormone increase prematurely and bees begin foraging as much as 2 weeks earlier than average. We used two experimental paradigms inspired by developmental biology to study how bees obtain information on changing colony needs that results in precocious foraging. An analog of "cell culture," with bees reared outside of colonies in different sized groups, revealed that worker-worker interactions exert quantitative effects on endocrine and behavioral development. "Transplants" of older bees to colonies otherwise lacking foragers demonstrated that worker-worker interactions also affect behavioral development in whole colonies. These results provide insights to a long-standing problem in the biology of social insects and further highlight similarities in the integration of activity that exist between individuals in insect colonies and cells in metazoans.

Age Factors↗
PubMed1992

Changes in brain amine levels associated with the morphological and behavioural development of the worker honeybee.

Changes in biogenic amine levels associated with the morphological and behavioural development of the worker honeybee are examined. A significant increase in amine levels in the head of the honeybee is associated with transition from the larval to pupal stage. Adult emergence is also accompanied by a significant increase in 5-HT levels in the brain, but no significant change in brain dopamine (DA) levels. NADA (N-acetyldopamine) levels increase during larval and pupal development, but in contrast to both DA and 5-HT, drop significantly during the transition from pupa to adult. Levels of DA in the brain of nectar and pollen forager bees, presumed to be among the oldest adults sampled, were found to be significantly higher than in nurses, undertakers or food storers. These results suggest that an age-dependent change in amine levels occurs in the brain of the worker bee. In the optic lobes, levels of DA and 5-HT were found to be significantly higher in pollen forager bees than in all other behavioural groups. Significant differences in amine levels in the optic lobes of nectar foragers and pollen foragers indicate that some differences in amine levels occur independent of worker age. The functional significance of differences in brain amine levels and whether or not biogenic amines play a direct role in the control of honeybee behaviour has yet to be established.

Aging↗
PubMed1992

Reproduction in worker honey bees is associated with low juvenile hormone titers and rates of biosynthesis.

Three experiments were performed to determine the role of juvenile hormone (JH) in worker reproduction in queenless colonies of honey bees. In Experiment 1, egg-laying workers had low hemolymph titers of JH, as did bees engaged in brood care, while foragers had significantly higher titers. Experiment 2 confirmed these findings by demonstrating that laying workers have significantly lower rates of JH biosynthesis than foragers do. In Experiment 3, ovary development was inhibited slightly by application of the JH analog methoprene to 1-day-old bees, but was not affected by application to older bees, at least some already displaying egg-laying behavior. These results, which are consistent with earlier findings for queen honey bees, are contrary to a common model of insect reproduction, in which elevated JH titers trigger ovary development, which then leads to oviposition. Previous experiments have demonstrated that JH regulates nonreproductive behavior in workers that is associated with colony division of labor; perhaps this function is incompatible with a traditional role for JH in reproduction.

Animals↗
PubMed1991

Stopping the pill.

Explore the source record for details and available documents.

Contraceptives, Oral, Combined↗
PubMed1991

Changes in haemostasis after stopping the combined contraceptive pill: implications for major surgery.

OBJECTIVE: To investigate the changes in haemostasis in the three months immediately after stopping the combined contraceptive pill. DESIGN: Prospective randomised study. SETTING: Family planning centre in London. SUBJECTS: 24 women aged 35-45 investigated before, during, and after six months' use of combined oral contraceptives containing 30 micrograms ethinyl oestradiol together with the progestogens desogestrel or gestodene. MAIN OUTCOME MEASURES AND RESULTS: Blood samples were taken immediately before and after six months of oral contraceptive use and one, two, four, six, eight, and 12 weeks after the pill had been stopped. During the six months of oral contraceptive use the plasma concentration of factor X and fibrinogen increased and that of antithrombin III decreased. Between two and six weeks after stopping the pill a rebound phenomenon occurred with plasma concentrations of antithrombin III increasing (mean change from baseline at two weeks 0.06 IU/l and at six weeks 0.10 IU/l) and fibrinogen decreasing (0.26 g/l change at two weeks and 0.40 g/l at six weeks). Factor X concentrations fell gradually and the values at eight weeks were not significantly different from those found before the combined pill was started. CONCLUSION: The combined pill should be stopped at least four weeks before major surgery, which carries the risk of postoperative thrombosis, to allow the potentially prothrombotic haemostatic changes that occur during its use to be corrected.

Adult↗
PubMed1991

Impact of prenatal testing on maternal-fetal bonding: chorionic villus sampling versus amniocentesis.

The process of maternal-fetal attachment, considered vital for normal infant development, begins during pregnancy and can be affected by a number of external factors. In this study the impact of prenatal testing on maternal-fetal bonding was evaluated in 253 women undergoing either first-trimester chorionic villus sampling (n = 101) or second-trimester genetic amniocentesis (n = 152). The women were evaluated by means of a modification of the Cranley Maternal-Fetal Attachment Scale, administered before and after the results of the prenatal diagnostic testing were made known to them (mean gestational ages of 10.6 and 15.7 weeks for the chorionic villus sampling group and 16.5 and 21.1 weeks for the amniocentesis group). The results showed: (1) that maternal-fetal attachment begins as early as 10 weeks' gestation and increases significantly as the pregnancy progresses, (2) that maternal-fetal attachment increases significantly, once the results are known to be normal, for both groups (p less than 0.001), (3) that this increase occurs about 5 weeks earlier for patients with chorionic villus sampling in comparison to those undergoing amniocentesis (p less than 0.001). Thus, with regard to the process of maternal-fetal attachment, first-trimester chorionic villus sampling appears to be preferable to second-trimester amniocentesis.

Amniocentesis↗
PubMed1991

A survey of Canadian psychiatric residents regarding resident-educator sexual contact.

BACKGROUND AND METHOD: A survey of all Canadian psychiatric residents was undertaken to ascertain the prevalence of resident-educator sexual contact in training programs, the residents' feelings about this contact, their knowledge of the ethical standards of the profession, and the extent of the information they had been given about this subject. An investigator-designed questionnaire was circulated to all psychiatric residents in Canada through the directors of postgraduate training programs. To ensure confidentiality, the residents returned their questionnaires directly to the investigators. RESULTS: Of the 314 respondents, 4.1% (N = 6) of the female residents and 1.2% (N = 2) of the male residents reported sexual involvements with their educators. Although the majority of these eight residents had positive or neutral feelings about the contact, 37.5% (N = 3) of the involved residents had mixed feelings. The residents' education concerning resident-educator sexual contact was strikingly sparse. CONCLUSIONS: This study highlights the need for inclusion of this tissue in residency programs.

Adult↗
PubMed1990

Changes in metabolism induced by oral contraceptives containing desogestrel and gestodene in older women.

Forty women aged 35-45 years were investigated to determine changes in haemostasis, lipids and lipoproteins whilst taking combined contraceptive pills containing the new third generation progestogens, desogestrel and gestodene. There was no statistically significant difference between the two preparations in any of the parameters studied. Women taking the combined pill showed increases in fibrinogen and factor X and a reduction in antithrombin III when compared with their control values. There were also small but significant increases in triglycerides and triglyceride-rich lipoproteins. Total high density lipoprotein cholesterol (HDL), high density lipoprotein-2 cholesterol (HDL2), high density lipoprotein-3 cholesterol (HDL3) and apolipoprotein A-1 were all increased at some stages of the treatment cycle, whereas low density lipoprotein cholesterol (LDL) showed a reduction in the first cycle of treatment. The changes in lipids and lipoproteins would not appear to increase the risk of cardiovascular disease, however the effects of the increase in the pro-coagulant factors are uncertain.

Adult↗
PubMed1990

Fatal attraction: the ethical and clinical dilemma of patient-therapist sex.

This article reviews the existing literature on the subject of patient-therapist sexual contact. Seven point one percent to 10.9% of male therapists and 1.9% to 3.5% of female therapists admit to engaging in intimate contact with patients. Offenders tend to justify their behaviour as being at least innocuous if not beneficial for the patients. The consequences to the patients include increased psychological and psychosomatic complaints, greater mistrust and anger towards men, hospitalization and suicide. Transference and countertransference issues which account for this behaviour are explored as is the issue of post-termination involvement. Education of physicians and residents concerning the temptations and dangers of this type of contact is strongly recommended.

Attitude of Health Personnel↗
PubMed1990

Problems in the treatment of premenstrual syndrome.

Three categories of treatments for premenstrual syndrome (PMS) have been proposed: those designed to correct the cause of the disorder; those designed for symptom relief; and those aimed at eliminating the menstrual cycle. Many of these recommendations are based on poor research with loose definitions of the disorder and uncontrolled open trials. This paper reviews the literature on treatment methods with emphasis on recent random, placebo controlled, double-blind studies. The most effective current management of PMS is a conservative one including accurate diagnosis, stress control, sensible levels of diet and exercise and perhaps the use of alprazolam in the premenstrual period. Other approaches such as the use of mefenamic acid and evening oil of primrose remain unproven. Progesterone has been proven uneffective. Further research is required into the value of antidepressant medication.

Alprazolam↗
PubMed1989

The psychologic effects of spontaneous abortion.

Although 14% to 18% of pregnancies end in spontaneous abortion, miscarriage is often not recognized as a significant occurrence. Women may experience grief reactions similar to those after the loss of a neonate. If the woman is not given an opportunity to deal with her grief, there may be continuing feelings of sadness, inadequacy and fearfulness as well as impairment in the relationships with her spouse and children. Methods of helping the couple during this time include acknowledging the significance of the loss, providing information, permitting the couple to see the fetus, if desired, and suggesting a memorial service. Some women may require individual or group therapy to deal with their feelings.

Abortion, Spontaneous↗
PubMed1989

Premenstrual syndrome: current knowledge and management.

Premenstrual syndrome (PMS) has become a popular self-diagnosis. Faulty research has led to confusion about the diagnosis, epidemiologic features, causes and treatment of this disorder. There is no proof that the premenstrual period is a time of increased violence. An association between menstrually related mood disorders and other psychiatric illness is also unproven. Despite many theories no definitive cause of PMS has been established, and controlled studies of various treatments have failed to find a universally effective approach. Conservative measures involving support, diet and exercise seem to help in most cases. The use of alprazolam and mefenamic acid may help some women. Rectal or vaginal progesterone therapy has been proven ineffective and should not be used.

Adult↗
PubMed1989

Predictors of postpartum adjustment.

Identification of women at risk for problems in postpartum adaptation could allow interventions that might prevent difficulties. Eighty-five women were followed from the second trimester of pregnancy to 12 months postpartum. One year postnatally, 27 women were found to have low global severity index scores on the Symptom Check List (SCL-90) (less than or equal to 0.16), while 17 women had high global severity index scores (greater than or equal to 0.46). The high scoring group were also significantly more dissatisfied with their marriages and their partners. The high scorers also had significantly higher global severity index scores and lower intimacy with spouse scores when measured at 12-16 weeks gestation. The SCL-90 and the Miller Social Intimacy Scale, when used in the second trimester of pregnancy, appear to predict the women who may have adjustment problems in the postpartum period.

Adaptation, Psychological↗
PubMed1989

Motivation for motherhood and the experience of pregnancy.

It is frequently assumed that becoming a mother is an essential step in the development of female identity. Although female hormones may increase a woman's readiness to care for an infant, there is no clear cut evidence of a hormonal basis for maternal feelings. A woman's desire to have and raise children is affected by cultural expectations and opportunities. Current analytical thinking, while viewing reproductive choice as being an important component of feminine identity, does not emphasize the necessity of having a child to feel feminine. Once pregnant, the woman works through issues related to body image, relationship with mother and husband, concerns for the fetus, fears about the future and her new vision of herself.

Animals↗