[Impacts of stochastic migration of seed and pollen on differentiation of plant population genetic structure]

The island model was extended to plant population with incorporation of the effects of stochastic migration of seed and pollen grain. Exact mean and variance of gene frequencies were formulated for each of three genomes with different modes of inheritance (bi-parental, paternal and maternal). Theoretical results indicate that stochastic migration in both seed and pollen may increase the variance of gene frequencies among populations, depending upon how large the variations of migration rate and/or migrant gene frequency are. Fluctuation in migration rate or in migrant gene frequencies of seed and pollen grain is also an important factor influencing population genetic structure, perhaps as important as the absolute value of migration rate. One important result is that the combined effect induced by the fluctuation of both migration rate and migrant gene frequency of seed and pollen can greatly intensify differentiation of population genetic structure. Application of these theoretical results in practical work was discussed in detail.

[18F]FDG-PET study in dementia with Lewy bodies and Alzheimer's disease

1. The authors report two siblings with dementia with Lewy bodies (DLB). Both the older brother and the younger sister underwent positron emission tomography (PET) studies with [18F]-2-fluoro-deoxy-D-glucose (FDG) during life. The FDG-PET study demonstrated unique and pronounced metabolic impairment in the occipital cortex in both patients. The clinical diagnosis of DLB in the sister was confirmed by autopsy. 2. FDG-PET images from 11 patients with Alzheimer's disease (AD), 7 patients with DLB and 10 age-matched normal subjects were obtained and analyzed by the statistical parametric mapping (SPM) method. The SPM demonstrated a widespread metabolic reduction in the DLB group. The reduction was particularly pronounced in the visual association cortex in the DLB group compared to the AD group irrespective of clinical severity of the disease. 3. These findings suggest that functional neuroimaging techniques, including FDG-PET, will provide a valuable diagnostic aid to differentiate DLB from AD, and this will help detect DLB patients in the early stage of the disease.

[Prediction of progression in patients with mild cognitive impairment using IMP-SPECT]

To examine the difference in functional brain imaging between mild cognitive impairment (MCI) and normal aging, we measured rCBF on functional brain imaging using 123I-IMP single photon emission computed tomography (IMP-SPECT) in 19 MCI patients who progressed to develop AD on follow-up and 23 probable Alzheimer's disease (AD) patients as well as 15 age-matched normal subjects. Baseline MMSE score was 25.3 (SD 1.2) in the MCI group and 17.5 (SD 3.3) in the AD group. The regions of interest (ROI) in the posterior cingulate gyrus, frontal, temporal and parietal cortices were drawn on the image of IMP-SPECT with reference to an individual MRI image. The rCBF ratio was calculated using ROI value in the cerebellum as a reference. Voxel-based analysis was also preformed using statistical parametric mapping (SPM). The rCBF ratio in the posterior cingulate gyrus was significantly reduced in the MCI group (mean 0.956, SD 0.080) and the AD group (mean 0.833, SD 0.118) compared to that in the normal group (mean 1.083, SD 0.084). In the frontal, temporal and parietal cortices, the rCBF ratio was significantly reduced only in the AD group compared to the normal group. At a fixed specificity of 80%, the diagnostic sensitivity in the discrimination between MCI patients and normal subjects was 80.5% when using rCBF ratio in posterior cingulate gyrus. In the SPM analysis, significant reduction of the rCBF in MCI group was observed only in the posterior cingulate gyrus, compared with normal subject group. Our results suggest that MCI patients presenting with a posterior cingulate hypoperfusion are at higher risk for transition from MCI to clinically recognizable AD.

18F-fluorodopa PET study of striatal dopamine uptake in the diagnosis of dementia with Lewy bodies

Using (18)F-fluorodopa PET and a constant 0.0062 influx rate in the putamen, dementia with Lewy bodies (n = 7) was distinguished from AD (n = 10) with a sensitivity of 86% and a specificity of 100%. A constant 0.0071 influx rate in the caudate yielded a sensitivity of 71% and a specificity of 100% for distinction of the two disorders. Despite a limited sample size, these findings suggest that assessing nigrostriatal dopaminergic function with (18)F-fluorodopa PET may be a useful diagnostic aid in cases of dementia with Lewy bodies while patients are alive.

Sequencing a specific kinetoplast DNA fragment of Leishmania donovani for polymerase chain reaction amplification in diagnosis of leishmaniasis in bone marrow and blood samples

A set of oligonucleotide primers I and II was developed by analyzing the specificity of a cloned kinetoplast DNA (kDNA) fragment of Leishmania donovani and sequencing the fragment. Polymerase chain reaction (PCR) was conducted with the primers to amplify a minicircle kDNA fragment (297 bp) to detect L. donovani in the bone marrow (22 samples), whole blood (16 samples), and serum (17 samples) of 22 patients with visceral leishmaniasis. All of 22 patients were diagnosed by microscopic identification. Control samples of bone marrow, whole blood, and serum were obtained from patients with leukemia and from healthy volunteers. In addition, 12 dogs were infected with L. donovani promastigotes for the PCR test. The total number of patients positive by PCR testing was 95.5% (21/22), with 91.0% (20/22) from the bone marrow, 68.8% (11/16) from the blood, and 29.4% (5/17) from the sera. Similar results were obtained in infected dogs. No amplification products were seen in control samples from humans or dogs. Our results suggest that PCR may be useful in detecting kDNA in the bone marrow and blood of patients with visceral leishmaniasis.

Attenuation of the neuropsychiatric effects of ketamine with lamotrigine: support for hyperglutamatergic effects of N-methyl-D-aspartate receptor antagonists

BACKGROUND

The cognitive, behavioral, and mood effects of N-methyl-D-aspartate (NMDA) receptor antagonists, such as phencyclidine and ketamine, have been used to study the effects of NMDA receptor dysfunction. Pharmacological modulation of the effects of NMDA receptor antagonists, such as ketamine, may lead to development of novel therapeutic agents for psychiatric illnesses such as schizophrenia. Preclinical studies indicate that some ketamine effects may be mediated through increased glutamate release. In this study, we tested the hypothesis that lamotrigine, a drug reported to inhibit glutamate release, will reduce the neuropsychiatric effects of ketamine in humans.

METHOD

Healthy subjects (n = 16) completed 4 test days involving the administration of lamotrigine, 300 mg by mouth, or placebo 2 hours prior to administration of ketamine (0.26 mg/kg by intravenous bolus and 0.65 mg/kg per hour by intravenous infusion) or placebo in a randomized order under double-blind conditions. Behavioral and cognitive assessments were performed at baseline and after administration of the medications.

RESULTS

Lamotrigine significantly decreased ketamine-induced perceptual abnormalities as assessed by the Clinician-Administered Dissociative States Scale (P<.001); positive symptoms of schizophrenia as assessed by the Brief Psychiatric Rating Scale positive symptoms subscale (P<.001); negative symptoms as assessed by the Brief Psychiatric Rating Scale negative symptoms subscale (P<.05); and learning and memory impairment as assessed by the Hopkins Verbal Learning Test (P<.05). However, lamotrigine increased the immediate mood-elevating effects of ketamine (P<.05).

CONCLUSIONS

Glutamate release-inhibiting drugs may reduce the hyperglutamatergic consequences of NMDA receptor dysfunction implicated in the pathophysiologic processes of neuropsychiatric illnesses such as schizophrenia. Further study is needed.

A randomized clinical trial of repetitive transcranial magnetic stimulation in the treatment of major depression

BACKGROUND

Multiple groups have reported on the use of repetitive transcranial magnetic stimulation (rTMS) in treatment-resistant major depression. The purpose of this study is to assess the efficacy of rTMS in unmedicated, treatment-resistant patients who meet criteria for major depression.

METHODS

Depressed subjects, who had failed to respond to a median of four treatment trials, were assigned in a randomized double-blind manner to receive either active (n = 10; 20 2-sec trains of 20 Hz stimulation with 58-sec intervals; delivered at 80% motor threshold with the figure-of-eight coil positioned over the left dorsolateral prefrontal cortex) or sham (n = 10; similar conditions with the coil elevated and angled 45 degrees tangentially to the scalp) rTMS. These sequences were applied during 10 consecutive weekdays. Continuous electroencephalogram sampling and daily motor threshold determinations were also obtained.

RESULTS

The group mean 25-item Hamilton Depression Rating Scale (HDRS) score was 37.2 (+/- 2.0 SEM) points. Adjusted mean decreases in HDRS scores were 14.0 (+/- 3.7) and 0.2 (+/- 4.1) points for the active and control groups, respectively (p <.05). One of 10 subjects receiving active treatment demonstrated a robust response (i.e., HDRS decreased from 47 to 7 points); three other patients demonstrated 40-45% decreases in HDRS scores. No patients receiving sham treatment demonstrated partial or full responses.

CONCLUSIONS

A 2-week course of active rTMS resulted in statistically significant but clinically modest reductions of depressive symptoms, as compared to sham rTMS in a population characterized by treatment resistance.

A preliminary approach to the theory of geographical gene genealogy for plant genomes with three different modes of inheritance and its application

This paper extends to hermaphrodite outcrossing plant populations the existing gene genealogy theories for a sample of genes randomly chosen from geographically discrete or continuously distributed populations. Three plant genomes (nuclear, chloroplast and mitochondrial DNA) with different modes of inheritance are considered separately due to the difference in migration rates. It is shown that on certain assumptions, the previous coalescence theories can be applied to plant by appropriate reparametrization of the effective population size and migration rate specific to each genome. One result is that estimation of the ratio of pollen to seed flow from a sample of n (n > or = 2) individual genes can be obtained in terms of the number of segregating sites between and within populations that are discretely distributed in space. Another result of theoretical interest is that in the discrete model of population structure, mean coalescent time is the shortest for the paternally inherited genes (cpDNA in conifers) and, given certain conditions, is the longest for the maternally inherited genes (cpDNA in angiosperms and mtDNA in conifers and angiosperms). However, these results are difficult to obtain in the model of population that is continuously distributed in space.

Impacts of seed and pollen flow on population genetic structure for plant genomes with three contrasting modes of inheritance

The classical island and one-dimensional stepping-stone models of population genetic structure developed for animal populations are extended to hermaphrodite plant populations to study the behavior of biparentally inherited nuclear genes and organelle genes with paternal and maternal inheritance. By substituting appropriate values for effective population sizes and migration rates of the genes concerned into the classical models, expressions for genetic differentiation and correlation in gene frequency between populations can be derived. For both models, differentiation for maternally inherited genes at migration-drift equilibrium is greater than that for paternally inherited genes, which in turn is greater than that for biparentally inherited nuclear genes. In the stepping-stone model, the change of genetic correlation with distance is influenced by the mode of inheritance of the gene and the relative values of long- and short-distance migration by seed and pollen. In situations where it is possible to measure simultaneously Fst for genes with all three types of inheritance, estimates of the relative rates of pollen to seed flow can be made for both the short- and long-distance components of migration in the stepping-stone model.

The use of pindolol with fluoxetine in the treatment of major depression: final results from a double-blind, placebo-controlled trial

BACKGROUND

Preliminary reports have suggested that concomitant institution of pindolol and serotonin reuptake inhibitors robustly hastens clinical response; however, contradictory evidence from a randomized double-blind, controlled trial was recently reported by this group in a population of depressed patients who were prescribed fluoxetine and pindolol. Herein, we report final results from an extended sample size.

METHODS

Drug-free outpatients with a major depressive episode were randomized in a double-blind manner to one of two treatment conditions: fluoxetine (20 mg daily) with pindolol (7.5 to 10 mg daily) or fluoxetine (20 mg daily) with placebo. After 6 weeks, patients were followed for 3 more weeks in a single-blind manner, on fluoxetine and placebo pindolol.

RESULTS

Eighty-six patients completed at least 1 or more weeks on protocol, with 45 and 41 patients randomized to the pindolol and placebo groups respectively. After 2 weeks on protocol, partial remission (i.e., at least 50% decrease in depression rating scores from baseline) rates for pindolol (16%) and placebo (19%) groups were comparable. By the study's end, a partial remission was achieved, at least transiently, for 67% of the pindolol group and 80% of the placebo group. Pindolol treatment was associated with statistically significant reduction in blood pressure and pulse as compared to the control group. The two groups did not have overall differences in rates of attrition, time to response, and side effects.

CONCLUSIONS

In accord with our previously published findings, these extended results do not support the efficacy of pindolol in hastening clinical response to fluoxetine in a patient population with predominantly chronic and recurrent depression.

Separation of Chinese Leishmania isolates into five genotypes by kinetoplast and chromosomal DNA heterogeneity

Leishmaniasis remains endemic in China, especially in the west and northwest frontier regions in central Asia. Epidemic outbreaks of both visceral and cutaneous forms of the disease have become a serious concern in view of such events occurring in neighboring countries. In the present study, we have begun to characterize available parasites as an initial step in understanding the epidemiology of leishmaniasis in central Asia. Nineteen Leishmania isolates collected since the 1950s from epidemiologically different foci in China were separated into five genotypes (Groups I-V) based on their polymorphisms in both kinetoplast (kDNA) and nuclear (nDNA) DNAs. Both kDNA and nDNA are conserved in Group I, which consists of six isolates, i.e., five cases of human kala-azar and one case of canine leishmaniasis isolated from three distant foci more than 30 years apart. In contrast, both kDNA and nDNA are heterogeneous in Group II, consisting of 10 isolates scattered in the plain area from the eastern coast to the western desert. This group includes five kala-azar cases, one post-kala-azar dermal leishmaniasis case, two sand fly isolates, and two canine isolates. The remaining three groups (III-V), two from great gerbils (Rhombomys opimus) and one from a kala-azar case, differ among themselves and from the aforementioned groups. Groups I, II/III, IV, and V contain isolates that have been recognized epidemiologically or typed isoenzymatically as L. donovani s.l., L. infantum s.l., L. turinica, and L. gerbilli, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of leishmania by kinetoplast DNA minicircle and cloning of minicircle

To develop a specific and sensitive method for the identification of Leishmania species and strains in China, Kinetoplast DNA (kDNAs) from 10 different isolates of Leishmania donovani and other species were analyzed by Southern and Dot hybridization. Our results showed significant diversities within different species and strains of Leishmania, which may be a useful criterion for taxonomic analysis. By Southern blot under different stringency conditions, we estimated that there is greater sequence heterogeneity between L. donovani isolated from dog and from human being in the same endemic focus than within the same isolate. Our Dot blotting assay with kDNA probe labelled by photobiotin differentiated species and isolates of Leishmania with as little as 10(4) parasites; so it is useful for field identification. The heterogeneity between isolates of L. donovani from patients in hilly and plain areas may have practical implications for disclosing the difference in endemicity. For the purpose of obtaining a large quantity of homogeneous minicircle, it was cloned and produced by recombinant pUC18.

[Studies on protective monoclonal antibodies to Leishmania donovani]

Kala-azar is increasing in incidence in some endemic areas of China, such as provinces of Sichuan and Gansu. Monoclonal antibodies have been shown to interfere with the cutaneous leishmaniasis infection in the experimental animals. We have now raised McAb against membrane antigen of promastigotes of L. donovani canine isolate (the pathogen of visceral leishmaniasis). In this paper we report 3 McAb which inhibit the growth of promastigotes in vitro culture by incorporation of 3H-thymine deoxyriboside, such as McAb 2B12-A8, 2H6-E3, in the presence of complement, showing strong inhibiting effects with a decrease in incorporation of 3H-TdR, 94-99.3% rate of inhibition, whereas the inhibition rate induced by McAb 1B1-C2 fluctuated in a range of 68-95%, which is identical with the results of macrophage infection inhibition test by the same McAb, 61-87%. The results of ultrastructural localization of L. donovani antigen by protective McAb 2H6-E3 with immunogold technique showed the gold particles, in clumps, widely distributed on the outer side of promastigotes membrane. According to the high density of localized gold particles, it is suggested that this antigen is abundant on the plasma membrane.