Hillary Voet

Alternation learning in obsessive-compulsive disorder

The Wisconsin Card Sorting Test (WCST) and an alternation learning task were administered to 15 women with obsessive-compulsive disorder (OCD) and 15 age-, sex-, education-, and intelligence-matched healthy controls. OCD patients were significantly slower on the WCST as compared to the controls. Their performance on the alternation learning task was impaired relative to the control group, though this difference was diminished when we used education as a covariate. We found a significant positive correlation between performance on the alternation task and severity of symptoms in the OCD group. Performance of similar alternation tasks is impaired by damage to the orbitofrontal cortex in nonhuman primates. Therefore the data presented support the hypothesis of orbitofrontal cortex dysfunction in OCD.

Serotonergic Dissection of Obsessive Compulsive Symptoms: A Challenge Study with m-Chlorophenylpiperazine and Sumatriptan

We have conducted a pharmacological challenge experiment in 10 medication-free obsessive compulsive (OC) disorder (OCD) patients. We used a placebo-controlled paradigm for m-chlorophenylpiperazine (mCPP) and sumatriptan challenges. Endocrine, physiological and behavioral variables were assessed at baseline and over a 3-hour period after the challenge. Both cortisol and prolactin were significantly elevated in OCD patients following mCPP administration. Both mCPP and sumatriptan caused significant OC symptom exacerbation with the response to sumatriptan being more robust. We conclude that the 5-HT1Dβ receptor may play a role in the pathophysiology of OCD.

The suicide brain: a review of postmortem receptor/transporter binding studies

The present review summarizes the last 15 years of research involving postmortem receptor/transporter binding studies on brains of suicide victims. It is our working hypothesis, on the basis of psychological, behavioral and epidemiological studies, that suicidal behavior is an independent unique behavioral entity with specific neurochemical characteristics. This review tries to test this hypothesis at the level of neurotransmitter receptors by using a different approach to data analysis. We suggest that this statistical approach, involving multivariate analyses, can contribute to the formulation of new hypotheses at the level of molecular biology and genetics. Such studies if undertaken in the future, would help define suicidal behavior as a psycho-neuro-pathological entity.

Neural activity at the human olfactory epithelium reflects olfactory perception

Organization of receptive surfaces reflects primary axes of perception. In vision, retinal coordinates reflect spatial coordinates. In audition, cochlear coordinates reflect tonal coordinates. However, the rules underlying the organization of the olfactory receptive surface are unknown. To test the hypothesis that organization of the olfactory epithelium reflects olfactory perception, we inserted an electrode into the human olfactory epithelium to directly measure odorant-induced evoked responses. We found that pairwise differences in odorant pleasantness predicted pairwise differences in response magnitude; that is, a location that responded maximally to a pleasant odorant was likely to respond strongly to other pleasant odorants, and a location that responded maximally to an unpleasant odorant was likely to respond strongly to other unpleasant odorants. Moreover, the extent of an individuals perceptual span predicted their span in evoked response. This suggests that, similarly to receptor surfaces for vision and audition, organization of the olfactory receptor surface reflects key axes of perception.

Factors affecting behavioral phase transition in the desert locust,Schistocerca gregaria (Forskål) (Orthoptera: Acrididae).

The behavior of the desert locust,Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), is adjusted rapidly to population density and is a phase characteristic. We used discriminant analysis to quantify the extent of phase transition from the solitary to the gregarious phase and accurately classify the phase status on the basis of two decisive behavioral parameters: nymphal activity and social interaction. Fecal extracts. examined by olfactometry, attract solitarious nymphs but do not contribute to behavioral phase transition. Neither do visual stimuli alone. Short-range olfaction of airborne volatiles slightly affects behavioral phase transition. Antennectomy abolishes density response. Cuticular lipid extract, containing presumptive contact pheromones, does not attract nymphs, but does significantly affect behavioral phase transition.

Evidence for genetic determination in human twins of olfactory thresholds for a standard odorant

Olfactory thresholds for four odorants were determined in groups of monozygotic and dizygotic human twins. Odorants were presented in an ascending dilution series in odorless solvent, using a three-way forced choice method. For two of the tested odorants, 5 alpha-androst-16-en-3-one and isoamyl acetate, the thresholds showed a strong genetic component. This was demonstrated by respective values of 0.78 and 0.73 for the intraclass correlation difference, and of z = 3.69 and z = 2.71 in a within-pair difference analysis. The results for isoamyl acetate are novel, and suggest that genetic polymorphism in the affinity of odorant receptor proteins contributes to the (nearly normal) threshold distribution for this odorant.

Investigation of splenic functions in canine monocytic ehrlichiosis

In order to determine the role of the spleen in the pathogenesis of canine monocytic ehrlichiosis (CME), the effect of splenectomy on the course of the acute phase of experimental was investigated. Intact and splenectomized dogs, sero-negative for Ehrlichia canis antibodies, were infected with the Israeli strain of E. canis. Serology, clinical signs and haematological parameters were recorded prior to infection, and over a period of 60 days post infection, and were compared between the intact and the splenectomized dogs. All dogs seroconverted for IFA E. canis antibodies by days 10 to 17 post infection. There did not appear to be any difference in the day of appearance or in the titer of anti-E. canis IgG antibodies, between the splenectomized and intact groups throughout the course of the study. During the acute stage, food consumption (percentage change) was significantly lower in the intact group compared to the splenectomized group (-66.3% and -25.3%, respectively, p < 0.0001). During this period, significant higher body temperatures were measured in the intact group (average of 39.76 degrees C vs. 38.96 degrees C, p < 0.0001). The haematocrit, red blood cell counts, haemoglobin concentrations and platelet counts were significantly lower (p < 0.05) in the intact group when compared to the splenectomized group during the whole course of the study. The clinical and the haematological findings in our study suggest that the disease process was milder in the splenectomized dogs compared to the intact dogs. The results of this study suggest that the spleen plays an important role in the pathogenesis of CME. Splenic inflammatory mediators and/or other splenic substances, are proposed to play a key role in the pathogenesis of the disease. Our results further substantiate the involvement of immune mechanisms in the pathogenesis of CME.

Enrichment of an Israeli ethnic food with fibres and their effects on the glycaemic and insulinaemic responses in subjects with non-insulin-dependent diabetes mellitus.

The effects of various sources of dietary fibre on the high glycaemic index of an Israeli ethnic food, melawach, were investigated in subjects with non-insulin-dependent diabetes mellitus (NIDDM). Locust-bean (Ceratonia siliqua) gum significantly decreased the glucose response to, and glycaemic index of, melawach in these diabetic subjects (P < 0.05). It also tended to decrease their insulinaemic response and insulinaemic index, but differences were not significant. Dietary fibre from lupin (Lupinus albus) and insoluble maize-cob fibre did not affect glucose and insulin levels in NIDDM volunteers. Subjects with a BMI < 30 kg/m2 exhibited similar glucose, but not insulin, responses to fibre. Locust-bean gum had no significant effect on glycaemic response in NIDDM subjects with a BMI > 30 kg/m2, whereas insulinaemic response decreased. The results indicate that foods containing the same nutrients in almost the same amounts, but differing in added dietary fibre, lead to different physiological responses in diabetic subjects. Furthermore, insulin response should be considered when fibre is incorporated into the diabetics diet.

Naturally occurring mastitis effects on timing of ovulation, steroid and gonadotrophic hormone concentrations, and follicular and luteal growth in cows

The effects of naturally occurring subclinical chronic or clinical short-term mastitis on time of ovulation, plasma steroid and gonadotropin concentrations, and follicular and luteal dynamics were examined in 73 lactating Holstein cows. Cows were sorted by milk somatic cell count and bacteriological examination into an uninfected group (n=22), a clinical mastitis group (n=9; events occurring 20+/-7 d before the study), and a subclinical chronic mastitis group (n=42). In addition, uninfected and mastitic cows were further sorted by their estrus to ovulation (E-O) interval. About 30% of mastitic cows (mainly subclinical) manifested an extended E-O interval of 56+/-9.2h compared with 28+/-0.8h in uninfected cows and 29+/-0.5h in the other 70% of mastitic cows. In mastitic cows with extended E-O interval, the concentration of plasma estradiol at onset of estrus was lower than that of uninfected cows or mastitic cows that exhibited normal E-O intervals (3.1+/-0.4, 5.8+/-0.5, and 5.5+/-0.5 pg/mL, respectively). The disruptive effect of mastitis on follicular estradiol probably does not involve alterations in gonadotropin secretion because any depressive effects of mastitis on pulsatile LH concentrations were not detected. Cortisol concentrations did not differ among groups. The preovulatory LH surge in mastitic cows with delayed ovulation varied among individuals, being lower, delayed, or with no surge noted compared with the normal LH surge exhibited by uninfected cows or mastitic cows with normal E-O interval (6.8+/-0.7 ng/mL). The diameter of the second-wave dominant follicle was larger and the number of medium follicles was smaller in uninfected and subclinical cows with normal intervals compared with subclinical cows with extended intervals (13.4+/-0.5 vs. 10.9+/-0.9mm, and 3.8+/-0.2 vs. 6.7+/-0.14 follicles, respectively). Mid-luteal progesterone concentrations were similar in uninfected and mastitic cows. These results indicate for the first time that around 30% of cows with subclinical chronic mastitis exhibit delayed ovulation that is associated with low plasma concentrations of estradiol and a low or delayed preovulatory LH surge.

Tonic immobility and open field responses in domestic fowl chicks during the first week of life

Abstract The ontogeny of the tonic immobility (TI) response in domestic fowl chicks was studied during the first week of life. The TI response of naive White-Leghorn Gallus domesticus male chicks ( N =5–9), was tested at the age of 1, 2, 3, 5 and 7 days. TI was induced dorsally and its duration, the number of induction trials and the latency of peeping were recorded. The TI response was strongly affected by age. It was poorly developed during the first 3 days of life, when the median TI duration in control chicks was 10 s and the mean number of induction trials 2.3±0.3. After the third day of life, TI duration increased by up to 15× and susceptibility by about two. Peeping latencies were very short throughout the first week and in many cases, peeping started long before the termination of TI. Immediately following recovery from TI, chicks were put in an open field and the latencies of walking and jumping and the number of steps, jumps and peeps were observed. No changes in either locomotion or vocalization in an open field were found between the third and fifth day. Furthermore, there was no correlation between any of the parameters of the TI and OF tests. The effect of habituation, which is known to attenuate the TI response, was studied by repeatedly subjecting chicks to TI and OF tests, once on each day of the experiment. Habituation prevented the increase in TI duration and susceptibility after the third day of life, but did not affect the OF response. The effect of aversive treatment, which was expected to increase TI, was examined by placing chicks in 5-cm deep tap water for 5 min, prior to testing. Treatment significantly attenuated TI on Day 1 and increased overall locomotion and peeping in open field.