Plaque Counts Research Articles

Comparison of techniques to determine the abundance of predatory bacteria attacking chromatiaceae

This work quantifies the number of bacterial predators attacking the population of Chromatiaceae in the hypolimnion of Lake Estanya to assess the potential role of these microorganisms in controlling phototrophic bacterial populations. The abundance of predators was estimated from total counts of infected prey cells and by counting plaque-forming units. In spite of the large difference between both determinations, their variations with depth and time followed very similar patterns. During the summer, in the hypolimnion, and during the winter in the entire lake, up to 60% of the prey cells had potential predators attached. In comparison, plaque counts showed that viable predators represented less than 1% of the population of the prey. Our results demonstrated that predatory bacteria were far more abundant than indicated by the low viable counts obtained, suggesting that they play a more important role in controlling phototrophic bacterial populations than is currently assumed.

Comparison of techniques to determine the abundance of predatory bacteria attacking chromatiaceae

This work quantifies the number of bacterial predators attacking the population of Chromatiaceae in the hypolimnion of Lake Estanya to assess the potential role of these microorganisms in controlling phototrophic bacterial populations. The abundance of predators was estimated from total counts of infected prey cells and by counting plaque-forming units. In spite of the large difference between both determinations, their variations with depth and time followed very similar patterns. During the summer, in the hypolimnion, and during the winter in the entire lake, up to 60% of the prey cells had potential predators attached. In comparison, plaque counts showed that viable predators represented less than 1% of the population of the prey. Our results demonstrated that predatory bacteria were far more abundant than indicated by the low viable counts obtained, suggesting that they play a more important role in controlling phototrophic bacterial populations than is currently assumed.

Basal ganglia mineralization in Alzheimer's disease: a comparative study of clinical, neuroradiological and neuropathological findings.

Fifty patients from a longitudinal study on 178 cases of Alzheimer's disease were examined at postmortem. The clinical features, CT-scans and neuropathological findings of five patients, with verified Alzheimer's disease, who had bilateral basal ganglia mineralization (BGM; 2 male, 3 female; age 78-91 years) were compared with the data of five age- and sex-matched Alzheimer patients without BGM and of five control subjects. Persecutory and other delusions (4 patients), persistent depression (2), parkinsonism (4), myoclonus (1) and epileptic seizures (1) were observed more frequently in the patients with BGM than was expected. The BGM-group had significantly lower counts of large neurons in the pallidum internum than the demented patients without BGM or the control group. We did not find other differences between the dementia groups regarding the CT-scans, or plaque, tangle and neuron counts in neocortex and brainstem. We suggest that the combined effects of Alzheimer pathology and BGM might lead to an increased manifestation of psychotic and motor disturbances.

Basal Ganglia Mineralization in Alzheimer’s Disease: A Comparative Study of Clinical, Neuroradiological and Neuropathological Findings

Fifty patients from a longitudinal study on 178 cases of Alzheimer's disease were examined at postmortem. The clinical features, CT-scans and neuropathological findings of five patients, with verified Alzheimer's disease, who had bilateral basal ganglia mineralization (BGM; 2 male, 3 female; age 78–91 years) were compared with the data of five age- and sex-matched Alzheimer patients without BGM and of five control subjects. Persecutory and other delusions (4 patients), persistent depression (2), parkinsonism (4), myoclonus (1) and epileptic seizures (1) were observed more frequently in the patients with BGM than was expected. The BGM-group had significantly lower counts of large neurons in the pallidum internum than the demented patients without BGM or the control group. We did not find other differences between the dementia groups regarding the CT-scans, or plaque, tangle and neuron counts in neocortex and brainstem. We suggest that the combined effects of Alzheimer pathology and BGM might lead to an increased manifestation of psychotic and motor disturbances.

3H]Nitrendipine binding in temporal cortex in Alzheimer's and Huntington's diseases

Specific [ 3H]nitrendipine binding which was shown to be calcium- and calmodulin-dependent was found to be significantly reduced in the temporal cortex in Alzheimer's disease compared to age-matched controls. Scatchard analysis revealed that this reduction was due to a loss in the number of cortical [ 3H]nitrendipine binding sites rather than a change in the affinity of the binding site in the Alzheimer patients. The reduction in cortical [ 3H]nitrendipine-specific binding was most marked in those Alzheimer's disease cases where the duration of the dementing illness was longer than two years. In contrast, no reduction in cortical [ 3H]nitrendipine binding was found in Huntington's disease. There was no significant correlation found between age (38–89 years) and [ 3H]nitrendipine binding in control cases, or between mean overall plaque counts and [ 3H]nitrendipine binding in the Alzheimer's disease cases. There was a significant correlation found between age (46–88 years) and [ 3H]nitrendipine binding in the Alzheimer's disease cases where the duration of the dementing illness was greater than two years.

Physical basis of cognitive alterations in alzheimer's disease: Synapse loss is the major correlate of cognitive impairment

We present here both linear regressions and multivariate analyses correlating three global neuropsychological tests with a number of structural and neurochemical measurements performed on a prospective series of 15 patients with Alzheimer's disease and 9 neuropathologically normal subjects. The statistical data show only weak correlations between psychometric indices and plaques and tangles, but the density of neocortical synapses measured by a new immunocytochemical/densitometric technique reveals very powerful correlations with all three psychological assays. Multivariate analysis by stepwise regression produced a model including midfrontal and inferior parietal synapse density, plus inferior parietal plaque counts with a correlation coefficient of 0.96 for Mattis's Dementia Rating Scale. Plaque density contributed only 26% of that strength.

Prospective neuropathological validation of Hachinski's Ischaemic Score in dementias.

The sensitivity and specificity of Hachinski's Ischaemic Score (IS) in the diagnosis of the vascular aetiology of dementia was studied in a series of 32 demented patients, dementia of the Alzheimer type (16), multi-infarct dementia (7), mixed dementia (6), Pick's disease (3), with neuropathological diagnosis as the point of reference. The IS distinguished between primary degenerative dementia and multi-infarct or mixed dementia. As single features of the IS "a positive history of stroke" and "a fluctuating course" showed differing prevalences in the latter two diagnostic categories. The IS labelled 21% of patients with primary degenerative dementia as having a vascular aetiology. The uncritical application of the IS to large samples in epidemiological studies may cause incorrect labelling of a significant proportion of patients with primary degenerative dementia as vascular dementia. These results are based on observations of long-term inpatients and depend on neuropathological criteria. While the definite diagnosis of DAT by threshold criteria concerning plaque and tangle counts is well established, neither clinical nor pathological evidence of stroke necessarily means that cerebrovascular disease has anything to do with a patient's dementia.

Bacteriophages as model viruses in water quality controlag

The potential of using bacteriophages as models for the fate of viruses in natural waters and water treatment is reviewed with special attention to the somatic coliphages, the F-specific RNA phages and phages of Bacteroides fragilis. Enumeration from highly contaminated samples can be achieved by plaque counts or enrichment methods; for less polluted samples a variety of concentration procedures is available and has been derived mainly from techniques developed for enteroviruses. International standardization of methods is necessary to promote further development of the field. Bacteriophages have promise as process indicators for viruses. F-specific RNA bacteriophages are a more homogeneous group than somatic coliphages and have generally a greater resistance. The value of somatic coliphages is further limited by their ability to multiply in unpolluted waters. Both groups are an index of sewage contamination rather than faecal contamination, hence their ecology is different from human enteric viruses. Phages of Bacteroides fragilis have been reported to occur exclusively in human faeces but little is known about their behaviour in water treatment processes.

Object recognition deficit in Alzheimer's disease: Possible disconnection of the occipito-temporal component of the visual system

An early object recognition impairment was observed in a patient presenting with a slowly progressive Alzheimer's disease. At autopsy, the cerebral cortex showed increased neuritic plaque and neurofibrillary tangle counts, particularly in the occipital and temporal lobes as compared to Alzheimer's disease cases with the usual clinical presentation and distribution of the neuropathological lesions (i.e., no early visual deficits and fewer pathological profiles in the occipital cortical areas than frontal or posterior parietal areas). This observation further supports the hypothesis that long corticocortical projections are selectively damaged in Alzheimer's disease and that the resulting disconnections may underlie specific neurological symptoms.

Quantitative analysis of a vulnerable subset of pyramidal neurons in Alzheimer's disease: I. Superior frontal and inferior temporal cortex

Various cytoskeletal proteins have been implicated in the cellular pathology of Alzheimer's disease. A monoclonal antibody (SMI32) that recognizes nonphosphorylated epitopes on the medium (168 kDa) and heavy (200 kDa) subunits of neurofilament proteins has been used to label and analyze a specific subpopulation of pyramidal neurons in the prefrontal and inferior temporal cortices of normal and Alzheimer's disease brains. In Alzheimer's disease, the distribution of neuropathological markers predominates in layers III and V in these association areas. In these neocortical regions, SMI32 primarily labels the perikarya and dendrites of large pyramidal neurons, predominantly located within layers III and V. In Alzheimer's disease, a dramatic loss of SMI32-immunoreactive (ir) cells was observed, affecting particularly the largest cells (i.e., cells with a cross-sectional perikaryal area larger than 350 microns 2). The staining intensity of the largest SMI32-ir neurons was significantly reduced in Alzheimer's disease cases, suggesting that an inappropriate phosphorylation of these cytoskeletal proteins may take place in the course of the pathological process. In addition, the SMI32-ir neuron loss and total neuron loss were highly correlated with neurofibrillary tangle counts, whereas such a correlation was not observed with neuritic plaque counts. These quantitative data suggest that SMI32-ir neurons represent a small subset of pyramidal cells that share certain anatomical and molecular characteristics and are highly vulnerable in Alzheimer's disease. Other studies have suggested that SMI32-ir neurons are likely to furnish long corticocortical projections. Thus, their loss would substantially diminish the effectiveness of the distributed processing capacity of the neocortex, resulting in a neocortical isolation syndrome as reflected by the clinical symptomatology observed in these patients. Such correlations between the expression of a selective cellular pathology and specific elements of cortical circuitry will increase our understanding of the molecular and cellular characteristics underlying a given neuronal subclass vulnerability in Alzheimer's disease or other neurodegenerative disorders.

Sequential inoculation as an adjunct in enteric virus plaque enumeration

The potential utility of sequentially inoculating a virus sample onto two different cultures of similar vs dissimilar cell lines was evaluated in conjunction with IDU (5-iodo-2′-deoxyuridine) treatment of the cells as a potential adjunct in viral plaque formation assays. This evaluation was done using laboratory grown human echovirus 7, human enterovirus 69 and human poliovirus 1, plus an environmental concentrate derived from sewage that contained indigenous untyped enteroviruses. The cell lines employed were BGM, RD, L-132 and HEL-299. Sequential inoculation generally yielded higher viral assay titers when compared with the more traditional method of simply introducing viral inoculum onto a culture of the first (initial) cell line and then completing the assay without removing that inoculum. When a permissive cell line (BGM or RD) was used for both the initial and final cultures in a sequential inoculation technique, the total plaque count titer from both the initial plus final cultures represented an average 35% improvement over the traditional method.

Enhancement of varicella-zoster virus plaquing efficiency with an agarose overlay medium

The infectivity titers of varicella-zoster virus (VZV) are routinely estimated by plaque production in cell culture. In this report, we show that plaque counts for VZV (strain Oka/Merck), in MRC-5 cell cultures, are significantly enhanced (54% average enhancement) by the use of an agarose overlay medium, as compared to a fluid overlay medium. Evidence also is presented that less variability ( P < 0.05) in plaque counts occurs with the use of an agarose overlay medium.

Correlation of Cognitive Skills in Nursing Home Patients with Histologic Alzheimer Changes in Specific Brain Areas

56 nursing home patients were examined psychometrically within 10 months before death. Correlation of three mnestic, three verbal and three visual-spatial skills, and six activities of daily living (ADL) with counts of senile plaques and neurofibrillary tangles in frontal, parietal, temporal, and hippocampal cortices of both hemispheres were calculated. The skill to copy a cube correlates exclusively with the severity of Alzheimer changes in the right parietal cortex, the skill to recall visually presented and named objects with right hippocampal changes. In addition, the skills of spatial orientation, calculation, and finger position imitation correlate exclusively with right hemispheric changes. The skill of temporal orientation correlates more with the left, alternating hand movements with the right hemisphere, and naming and other verbal skills equally with changes in both hemispheres. Six of the nine cognitive skills correlate best with hippocampal changes, while ADL correlate best with parietal and not significantly with hippocampal changes. Global clinical dementia ratings as well as global pathological scores are insufficient to explain the deficits in variably severe cortical changes, and they are not adequate parameters for counselling patients, their relatives, or coaching staff in nursing homes.

Subpopulations of somatostatin 28-immunoreactive neurons display different vulnerability in senile dementia of the Alzheimer type

We tested whether the vulnerability of somatostatin (SST) neurons in senile dementia of the Alzheimer type (SDAT) depended upon their co-localization with neuropeptide Y (NPY). Density estimates of SST28- and NPY-immunoreactive neurons and percentage of double-labeled SST-NPY neurons were obtained in the cortex (areas 9 and 25) and the bed nucleus of stria terminalis (BST), in 6 SDAT and 5 control cases. Counts of senile plaques (SP) and neurofibrillary tangles (NFT) were done on thioflavin S stains. In both cortical areas, a decrease in the density of SST28-IR neurons was found in SDAT cases (−60% in area 25 and −80% in area 9), whereas density of NPY-IR neurons was unchanged. Accordingly, the proportion of single-labeled SST neurons decreased; this decrease was significantly correlated with SP ( r = −0.89, P < 0.001). We conclude that single SST-IR neurons, in cortical layers II–III, and V, are preferentially lost relative to co-localized SST-NPY neurons. In the BST, no significant reduction of SST-IR, NPY-IR neurons nor of the percentage of single labeled SST neurons was found, despite the presence of SP. Thus one subpopulation of SST neurons, defined by associated neurochemical characters (not co-localized with NPY nor with NADPH diaphorase) and by topography (cortical layers III and V) appears to be particularly vulnerable in SDAT. The potential importance of their position in neural circuitry is emphasized.

A pathological study of the association between Lewy body disease and Alzheimer's disease.

The possibility of an association between Parkinson's disease and Alzheimer's disease has been examined by studying the age-specific prevalence of Lewy bodies in the substantia nigra in a group of 273 control cases without Parkinson's disease and 121 cases of Alzheimer's disease. The substantia nigra was also studied in 14 cases of Down's syndrome, 13 of which had cortical Alzheimer pathology. Twelve (7.8%) of the controls aged over 60 years showed nigral Lewy bodies. There was mild nerve cell degeneration and/or an extranigral distribution of Lewy bodies, suggestive of presymptomatic Parkinson's disease. Twenty five (22.5%) of the Alzheimer's disease cases over 60 years showed Lewy bodies, but only 14 (14.0%) of these had mild nigral cell loss consistent with presymptomatic Parkinson's disease. No case of Down's syndrome had Lewy bodies. Counts of tangles and plaques in hippocampus, frontal and temporal cortex were lower in cases of Alzheimer's disease with Lewy bodies compared with those without, but cortical choline acetyltransferase (ChAT) activities were similar. This suggests that Lewy body degeneration in the nucleus basalis of Meynert contributes to the deficit of cortical ChAT, but not to the cortical Alzheimer pathology. The relatively small difference in the prevalence of Lewy bodies between controls and Alzheimer's disease could be explained by the additive effects of Lewy body and tangle pathology causing dementia, rather than a greater than chance association between Parkinson's disease and Alzheimer's disease.

Factors affecting virus plaque confirmation procedures

Direct plaque counts obtained by using the monolayer cell culture assay technique reliably confirmed the number of viruses isolated. Analysis revealed some significant differences in the false-positive rate, depending on the test method used or virus samples evaluated. Plaques from laboratory stock viruses showed a higher confirmation rate than sewage plaque isolates. Test results with laboratory stock viruses suggested that confirmation rates may be affected by virus types present in the sample. Plaques picked by the stab and scrape method and immediately passed into cell culture tubes produced the most reliable counts as compared to those picked by the stab only method or those stored at −70°C in Earle's balanced salt solution with or without fetal calf serum. Plaque confirmation using this method was 90% or better. Although the term ‘false positive plaque’ has been applied to a particular plaque that was not confirmed, five of ten plaques picked by the stab and scrape method in one series of experiments were confirmed when repicked by the same method from original plaque bottles, indicating that a substantial number of unconfirmed plaques may be caused by plaque transfer techniques.

Prevalence of symptoms of dyspepsia in the community.

To study the prevalence of dyspepsia in the community a postal questionnaire was sent to 2697 patients who were selected at random from the lists of patients registered in two health centres in Hampshire. A total of 2066 returned questionnaires were suitable for analysis (response rate 77%). It was found that the six month prevalence of dyspepsia was 38%. There was considerable overlap between symptoms of heartburn and upper abdominal pain, with over half of patients with dyspepsia experiencing both. One in four of these patients had consulted their general practitioner during that time. The proportion of patients with dyspepsia who consulted their general practitioner varied widely among the eight doctors who participated in the study, from 17% to 45%. Frequency of symptoms tended to fall with age, particularly in men, while the proportion of patients with dyspepsia who sought medical advice increased with age. Almost one in five of the 2066 patients had been investigated with radiology or endoscopy at some time, and 143 (7%) of them claimed to have had a diagnosis of peptic ulcer.

半導体ＴｉＯ２微粒子配合歯磨剤の臨床応用 う蝕原性細菌との関連性

We examined changes in S. mutans, lactobacilli, total streptococci, and total anaerobic bacteria counts in plaque and saliva, when college student volunteers used toothpaste containing semiconductor TiO2, having bactericidal activity for S. mutans in vitro. S. mutans counts of plaque in subjects using toothpaste containing semiconductor TiO2 (TiO2 subjects) decreased and more significantly with time decreased than those of subjects using control paste (control subjects) after 2 weeks (p<0.01). Comparison of S. mutans counts between subjects using toothpaste contained TiO2 without semiconductor effect and control subjects were not significant. Lactobacilli counts of plaque in TiO2 subjects was also more sxgnificantly decreased than those in control subjects after 2 weeks (p<0.05). Salivary cariogenic bacterial counts were not changed by using toothpaste containing semiconductor TiO2.We suggest that toothpaste containg semiconductor TiO2 effective by to decreases S. mutans in plaque and contributes to the prevention of dental caries.

Chapter 33 The cholinergic receptor system of the human brain: neurochemical and pharmacological aspects in aging and Alzheimer

The cholinergic system of the brain has been implicated in memory function. Evidence for this role is anatomical, physiological and pharmacological. In all diseases, pathological and biochemical lesions in the cholinergic neuron are localized mainly to the presynaptic region. Alterations include biochemical and morphological changes in the structures storing, synthesizing and releasing acetylcholine (ACh) and possibly also in cholinergic receptors regulating ACh release. In a comparison between cholinergic terminals in the central nervous system of normally aged and Alzheimer disease (AD) patients, it is apparent that muscarinic and nicotinic receptors are not equally affected. A survey including percent changes in nicotinic receptors in the frontal cortex of AD patients reveals a striking difference from aging normal controls. Both biopsy and autopsy studies show that in contrast with muscarinic receptors, the number of nicotinic receptors is strongly reduced in the frontal cortex of AD patients. This decrease correlates closely to pathological and clinical findings. Biochemical findings such as AChE and ChAt activity and nicotinic receptor binding also correlate with pathology and clinical findings. The results suggest that biochemical data obtained from a cortical biopsy may correlate more closely to the clinical picture than histological results based purely on counts of neuritic plaques and tangles.

Comparison of four staining methods on the detection of neuritic plaques

The sensitivities of four staining methods for detecting the presence of neuritic plaques in the normal aging, Alzheimer disease (AD) and Down's syndrome (DS) brains were compared. The Bielschowsky method and immunostaining with monoclonal antibody (4G8, IgG2b) to beta-amyloid revealed the highest numbers of plaques. The thioflavin S-staining method showed about 38%-70% of plaques as shown by the Bielschowsky method. The Bodian method is the least sensitive method revealing about 26%-39% of plaques as compared with the Bielschowsky method. In the first part of this study, serial sections (6 microns) of the plaques from AD and DS brains were cut and stained with Bielschowsky, thioflavin S and Bodian methods, respectively. In the second part, Bielschowsky and immunostaining methods were used to stain serial sections (6 microns) of plaques from the same block of brain tissue. A Zeiss Axiophot fluorescence microscope, coupled with the Cambridge Quantiment 970 and Zeiss Videoplan computerized image analyzers, was used to quantify the number of plaques. Both Bielschowsky and immunostaining methods revealed the presence of both the peripheral zone (halo) and the central core of a classical plaque and resulted in the highest plaque counts. The central core of the thioflavin S-stained plaques were still clearly present, but the peripheral zone was barely visible. In Bodian stain, however, both central core and peripheral zone were poorly stained and not detectable by computer. They were quantified by human eye observation. The Bielschowsky method and immunostaining with pretreatment with formic acid are, therefore, the most sensitive methods showing the highest contrast of plaque image and thus facilitate the quantification of plaque by computer.(ABSTRACT TRUNCATED AT 250 WORDS)