Biomedical subjects

L Korbo

Publications and source records attributed to L Korbo.

12 recordsLinked to original sources

PubMed2004

No evidence for loss of hippocampal neurons in non-Alzheimer dementia patients.

OBJECTIVE: To use stereological methods for estimating the total number of neurons in hippocampi of non-Alzheimer demented patients. MATERIAL AND METHODS: Hippocampi from six women with severely impaired memory but without Alzheimer pathology were compared with six mentally intact age-matched female controls. The total number of neurons was estimated in the granule cell layer of the dentate gyrus, the hilus of the dentate gyrus, the pyramidal cell layer of CA3 and CA2, the pyramidal cell layer of CA1 and the cellular layer of subiculum using the optical fractionator. RESULTS: The total neuron number was the same in the dementia cases, 22.4 x 106, compared with 22.7 x 106 in the controls (P = 0.85). No region-specific group differences or side difference were found. Two cases without clinical signs of dementia but with abundant plaques and tangles in hippocampus and neocortex had total neuron numbers within normal limits. CONCLUSION: Our results indicate that severely impaired memory can occur in the presence of intact numbers of hippocampal neurons in non-Alzheimer dementia and that nerve cell loss in the hippocampus might be characteristic for Alzheimer's disease, and perhaps other forms of primary cortical dementia.

Aged↗

PubMed2002

Early brain atrophy in HIV infection: a radiological-stereological study.

Patients with the acquired immunodeficiency syndrome (AIDS) frequently develop neurological abnormalities, and atrophy has been reported in neuropathological studies of brains from patients with AIDS. Our aim was to see whether increased ventricular volume, indicating central cerebral atrophy develops at an early stage of HIV-infection, before patients are severely immunodeficient. We also wished to follow ventricular size over time and to investigate whether enlargement would be more marked in patients, who became clinically demented. We studied 32 HIV-seropositive men who had several CT studies. At the time of the first CT the patients were divided into two groups, an immunocompetent group (IC) with CD4 cell count >400 and an immunodeficient group (ID) with CD4 cell count <400. These were compared with a control group of 44 seronegative men. Subsequent CT studies were used to measure changes in ventricular size with time. Ventricular volume was estimated with an unbiased stereological method previously applied to CT. Mean (geometric) ventricular volume was 15 ml (6-54 ml) in the controls, 23 ml (10-72 ml) in the IC group and 27 ml (8-80 ml) in the ID group. The increase in size in both patient groups was statistically significant compared with controls: P=0.005 (IC) and 9 x 10(-5)(ID). Regression analysis of the follow-up CT studies showed a significant increase in volume in the HIV group (r=0.74, P=0.002), but not in the AIDS group (r=0.41, P<0.1).

Adult↗

PubMed2000

No loss of hippocampal neurons in AIDS patients.

Acquired immunodeficiency syndrome (AIDS) is often accompanied by neurological disorders and neuropathological abnormalities. A loss of up to 30% of the neocortical neurons in brains from AIDS patients has been demonstrated in several studies. This neuron loss appeared to have no relationship with either the presence of clinical dementia or HIV encephalitis. The hippocampal region of the brain is an essential component of learning and memory processes and it is severely affected in a number of diseases, including temporal lobe epilepsy and Alzheimer's dementia. In view of the reports of a considerable loss of neocortical neurons, the aim of the present study was to investigate the degree to which neurons may be lost in hippocampus of AIDS patients. A stereological method, the optical fractionator, was used to estimate the total number of neurons in the five subregions of the hippocampus of nine AIDS patients and ten controls. There were no statistically significant differences in the group means of the number of neurons in any of the subdivisions. This result is discussed in the light of the large loss of neurons in the neocortex reported to take place in AIDS patients.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Glial cell loss in the hippocampus of alcoholics.

Alcohol abuse is often accompanied by cognitive impairment. Memory and concentration problems, especially, are described in neuropsychologically tested abstinent alcoholics. This impairment seems to be reversible, because a neuropsychological study has reported that after >5 years of abstinence, former alcoholics performed normally compared with a control group. The neuropathological correlate to the cognitive impairment associated with alcoholism is still under debate. Hippocampus is an area of the brain primarily involved in learning and memory, and the hippocampus is affected in several demential diseases. Over recent years, it has become evident that the glial cells in the brain, especially the astrocytes, play a central part in many activities that are critical to the normal functions of the brain. The total number of neuron and glial cells in the hippocampus was estimated in five severely affected alcoholics and five controls with an unbiased stereological technique: the optical fractionator. A statistically significant loss of 37% of the glial cells was found globally in the hippocampus of the alcoholics compared with controls. A reduction of astrocytes and oligodendrocytes and, to a lesser degree, microglial cells accounted for this loss. No loss of neurons was found in the hippocampus from alcoholics. The loss of glial cells and the potential for regeneration of these cells after cessation of alcohol abuse is discussed in the light of the results of clinical studies of former alcoholics.

Adult↗

PubMed1996

Neuronal loss in hippocampus in rats exposed to toluene.

Both clinical and epidemiological studies of the effects of exposure to toluene have shown that long-term exposure may result in chronic toxic encephalopathy, where one of the major symptoms is memory deficits. We have attempted to identify the structural basis of the toxic effects of toluene in the hippocampus, a region of the brain known to be involved in learning and memory processes and well suited for stereological analysis. Rats were exposed to 1500 ppm of toluene, six hours per day, five days per week for six months. This was followed by a four-month-period without exposure prior to sacrifice. The total number of neurons in each of the five subdivisions of hippocampus of six exposed and six control rats was estimated with the optical fractionator. A statistically significant neuron loss of 16% was found in regio inferior (CA3 and CA2) of the exposed rats.

Animals↗

PubMed1995

The distributions of Purkinje cell perikaryon and nuclear volume in human and rat cerebellum with the nucleator method.

The Purkinje cells are among the largest cells in the central nervous system and are the output cells of the cerebellar cortex. They are, therefore, of special interest in cerebellar diseases. The estimation of total number and mean perikaryon and nuclear volume of Purkinje cells in five normal human and nine rat cerebella were obtained using unbiased methods based on stereological principles. The average total number of Purkinje cells was 30.5 x 10(6) (Coefficient of variation, CD = S.D./mean = 0.13) in humans and 0.61 x 10(6) (0.21) in rats. Thus the total number of Purkinje cells was 50 times higher in the human cerebellum compared with rats, while numerical density (number/mm3) was 13 times lower in humans (0.81 x 10(3)) compared with rats (10.1 x 10(3)). An unbiased stereological principle, the nucleator, was applied to estimate the volume of Purkinje cell perikarya and nuclei. In humans the average geometric mean volume of Purkinje cell perikaryon is 12,400 microm3 (interindividual coefficient of variation = 0.08), which is about three times larger than in rats, 4900 microm3 (CVi = 0.09). The intraindividual distributional variation (CVd) in perikaryon volume is much larger in humans compared to rats (CVd = 0.72 vs 0.32). One of the differences between the two species is the simple proportionality between perikaryon and nucleus size i humans, whereas larger Purkinje cells have relatively larger nuclei in the rat.

Aged↗

PubMed1994

[AIDS with apoplectic onset].

Four cases with an apoplectic debut of AIDS are reported. Two of the patients had not earlier been identified as being HIV-positive. In three patients, the underlying cause was probably cerebral toxoplasmosis. It is important to consider AIDS in the differential diagnosis of stroke, particularly in young adults.

AIDS-Related Opportunistic Infections↗

PubMed1993

Total numbers of various cell types in rat cerebellar cortex estimated using an unbiased stereological method.

A new and efficient stereological method for estimating the total number of the different cell types in rat cerebellar cortex is presented. The cells have been subdivided into the following categories: Purkinje cells, granule cells, Golgi cells, glial cells in the granular layer, Bergmann glial cells and neurons and glial cells in the molecular layer. The method has been used to estimate the total number of some of the cell types in rats exposed to orally administered toluene at doses of 200, 400 and 800 mg/kg/day for 12 weeks compared with a control group. No statistically significant differences were found between the exposed and non-exposed animals. The described method can be used in a number of both biological and experimental studies. With the use of new stereological methods it is possible to get precise estimates of total cell numbers in a much shorter time than earlier required. This makes it possible to improve the reliability of the final result by increasing the number of cases processed.

Animals↗

PubMed1992

A quantitative study of the human cerebellum with unbiased stereological techniques.

Estimates of total number of different neuron and glial cell types in the dentate nuclei and the four major regions of the human cerebellum were obtained by new stereological methods. With the optical disector and Cavalieri methods, the total number of neurons and glial cells in the human cerebellum of five elderly men was estimated to be 105,000 x 10(6) (coefficient of variation, CV = 0.13). Of this total, the granule cells comprised 101,000 x 10(6) (CV = 0.13) and the Purkinje cells comprised 30.5 x 10(6) (CV = 0.13) of the neurons. The mean of the total number of neurons in the dentate nucleus was 5.01 x 10(6) (CV = 0.28). The average surface area of the human cerebellum was estimated to be 1160 cm2 (CV = 0.29). The rationale for the different sampling schemes used to quantify the various cell types is described.

Cell Count↗

PubMed1990

An efficient method for estimating the total number of neurons in rat brain cortex.

An efficient method for the unbiased estimation of the total number of neurons in rat brain cortex is presented. The method is reasonable fast, the counting procedure takes 2-3 h per rat, and gives an estimate of the total neuron number in cortex cerebri with an CE of 0.10. The rat cerebral cortex is found to have a mean volume of 253 mm3 and to contain a mean of 21 million neurons. The method has been used in a neurotoxicologic study, in which rats were given toluene perorally in doses of 200, 400 and 800 mg/kg/day, respectively, for 12 weeks, followed by an exposure-free period of 4 weeks. The total number of neurons in rat brain cortex cerebri showed no significant difference between exposed and non-exposed animals. The applicability of the method is discussed.

Animals↗

PubMed1988

The new stereological tools: disector, fractionator, nucleator and point sampled intercepts and their use in pathological research and diagnosis.

The new stereological methods for correct and efficient sampling and sizing of cells and other particles are reviewed. There is a hierarchy of methods starting from the simplest where even the microscopic magnification may be unknown to the most complex where typically both section thickness and the magnification must be known. Optical sections in suitably modified microscopes can be used to improve the ease and speed with which even the most demanding of these methods are performed. The methods are illustrated by practical examples of applications to a wide range of histological entities including synapses, neurons and cancer cells, glomerular corpuscles and ovarian follicles.

Animals↗

PubMed1988

Some new, simple and efficient stereological methods and their use in pathological research and diagnosis.

Stereology is a set of simple and efficient methods for quantitation of three-dimensional microscopic structures which is specifically tuned to provide reliable data from sections. Within the last few years, a number of new methods has been developed which are of special interest to pathologists. Methods for estimating the volume, surface area and length of any structure are described in this review. The principles on which stereology is based and the necessary sampling procedures are described and illustrated with examples. The necessary equipment, the measurements, and the calculations are invariably simple and easy.

Humans↗