Biomedical subjects
M Kohn
Publications and source records attributed to M Kohn.
Gender differences in age effect on brain atrophy measured by magnetic resonance imaging.
A prospective sample of 69 healthy adults, age range 18-80 years, was studied with magnetic resonance imaging scans (T2 weighted, 5 mm thick) of the entire cranium. Volumes were obtained by a segmentation algorithm that uses proton density and T2 pixel values to correct field inhomogeneities ("shading"). Average (+/- SD) brain volume, excluding cerebellum, was 1090.91 ml (+/- 114.30; range, 822.19-1363.66), and cerebrospinal fluid (CSF) volume was 127.91 ml (+/- 57.62; range, 34.00-297.02). Brain volume was higher (by 5 ml) in the right hemisphere (P less than 0.0001). Men (n = 34) had 91 ml higher brain and 20 ml higher CSF volume than women (n = 35). Age was negatively correlated with brain volume [r(67) = -0.32, P less than 0.01] and positively correlated with CSF volume (r = 0.74, P less than 0.0001). The slope of the regression line with age for CSF was steeper for men than women (P = 0.03). This difference in slopes was significant for sulcal (P less than 0.0001), but not ventricular, CSF. The greatest amount of atrophy in elderly men was in the left hemisphere, whereas in women age effects were symmetric. The findings may point to neuroanatomic substrates of hemispheric specialization and gender differences in age-related changes in brain function. They suggest that women are less vulnerable to age-related changes in mental abilities, whereas men are particularly susceptible to aging effects on left hemispheric functions.
Magnetic resonance imaging in schizophrenia. I. Volumetric analysis of brain and cerebrospinal fluid.
The study reports magnetic resonance imaging data for 42 patients with schizophrenia and 43 normal controls. Volumetric measures were obtained with a validated computerized algorithm for segmentation of cranial volume into brain tissue and central and peripheral cerebrospinal fluid (CSF), with high inter-operator reliability. Patients did not differ significantly in whole-brain volume, but had higher whole-brain CSF volume and higher ratios of ventricular and sulcal CSF to cranial volume. Covarying age and education did not affect the differences. However, there was considerable overlap both in CSF volumes and in volume-cranium ratios, and most patients were within the normal range. This suggests that anatomic changes reflected in CSF can provide a limited substrate for schizophrenia and may apply only to subpopulations. Although there was no gender x diagnosis interaction, the results for sulcal CSF were significant only for men, whereas for women, the ventricular ratios were marginally higher in patients.
Resistance levels of nine mosquito species to 4% DDT in Phnom Penh, Kampuchea.
According to the standard WHO method criteria, the mosquitoes Anopheles campestris and Culex vishnui were found to be susceptible to DDT in the territory of Phnom Penh. An. vagus and An. sinensis were approximately at the limit of susceptibility and the remaining five species (Aedes vexans, Cx. tritaeniorhynchus, Cx. fuscocephala, Cx. gelidus, Cx. bitaeniorhynchus) were found to be more or less resistant. Except for An. vagus, the males of all species were more susceptible than the females.
Susceptibility of adult Aedes aegypti (L.) and Culex quinquefasciatus Say (Diptera; Culicidae) to DDT in Kampuchea.
The susceptibility to 4% DDT was tested in adult Aedes aegypti and Culex quinquefasciatus mosquitoes collected in houses in Phnom Penh (Kampuchea). It was found that in spite of the fact that insecticide treatment had not been performed for many years, the populations of both species as a whole remained resistant. However, there were some differences in the susceptibility between males and females and between engorged and hungry females. Possible causes of these differences are discussed in the present paper.
Occurrence of Aedes aegypti (L.) and Culex quinquefasciatus Say (Diptera, Culicidae) in houses of different constructions in Phnom Penh, Kampuchea.
The relation between the number of mosquito specimens of the most abundant species Aedes aegypti (L.) and Culex quinquefasciatus Say and the construction of houses which they inhabited was studied. The effect of the building materials and of the height at which the floor was situated above the ground were assessed in five and four localities, respectively. It was found that in the localities having the character of a town the mosquitoes were most abundant in houses constructed from corrugated plate and in those the floor of which was situated 2-3.5 m above the ground. In the locality of a village character, the mosquitoes were most numerous in brick houses with the floors at the ground level.
A survey on indoor resting mosquito species in Phnom Penh, Kampuchea.
Indoor resting mosquitoes were collected in 7 localities (250 houses) of Phnom Penh at various periods. The mosquitoes were collected for 8 min in every house by means of an aspirator and net. A total of 16 species of mosquitoes resting in houses were found, one of them for the first time in Kampuchea. Culex quinquefasciatus was the predominant species in 6 of the localities observed; its predominance in houses was more or less evident; Aedes aegypti prevailed in one locality. The percentage of A. aegypti predominance in houses corresponds with the risk of occurrence of dengue haemorrhagic fever. Anopheles vagus was found resting in higher abundance in houses of one locality. This fact is of little epidemiological significance because of the zoophilic character of An. vagus in Kampuchea. On the other hand even uncommon occurrence of Anopheles subpictus found in houses may signalize a possibility of an endemic occurrence of malaria in Phnom Penh.
Structure of the Aedes aegypti (L.) and Culex quinquefasciatus Say (Diptera: Culicidae) populations in the houses of Phnom Penh (Kampuchea).
Sex ratio and engorged females ratio were studied in the main mosquito species populations (Aedes aegypti, Culex quinquefasciatus and partially Anopheles vagus) in the houses of Phnom Penh. Collections were carried out in 7 different localities, including area from the centre of the town to the periphery. In Ae. aegypti and C. quinquefasciatus populations females were dominant in 5 localities, while males were dominant in 2 localities. Engorged females were predominant over unfed ones in all cases (collections were always carried out in the morning). Structure of population varied slightly according to the date of collection. The influence of two main factors, character of locality and monthly amount of rainfall, on structure of mosquito population is discussed.
[Post-traumatic breast cancer: 14 cases. Biological interpretation].
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Life prolongation: views of elderly outpatients and health care professionals.
A peculiar dynamic in communication exists between those who are most likely to be involved in life-prolongation decisions. We found that both the elderly and health care professionals talk about life-prolongation, but not with one another; that they consider some of the same factors as they think about the life-prolongation decision; and that most of them believe physicians should be responsible for initiating discussion. However, the physician or health care professional who wishes to avoid crisis situations also is reluctant to broach the issue for fear of unnecessarily alarming or compromising the defense mechanisms of the patient. The patient remains patient, waiting--with fears of dependency, memories of previous life-threatening experiences, and deep sensitivity for suffering--for the physician to initiate the discussion. Is a mediator such as a family member necessary in these situations? Is the hospital environment not conductive to discussion of less than heroic efforts?
Child psychiatric diagnosis by computer algorithm: theoretical issues and empirical tests.
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Common use of diagnostic imaging for childhood wetting (enuresis): a survey of practicing paediatricians in the Federal Republic of Germany and West Berlin.
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[Induction of objective responses by an anticancer chemotherapy based on the prolonged combination of bleomycin and cisplatin. 1062 cases].
A cis-platin + bleomycin combination, sometimes associated with a third cytostatic drug, was administered for prolonged periods to 1062 cancer patients previously subjected to a wide variety of treatments. The objective response rate was about 70% in localized squamous cell and anaplastic bronchial carcinoma and 40% in bronchial adenocarcinoma and metastatic squamous cell carcinoma. Cancers of the head and neck responded in 70% of the cases before irradiation and in 30% after irradiation. Other epidermoid tumours responded objectively in the proportion of 45%, as did 58% of metastatic and refractory breast cancers. These results were not clearly improved by any of the other cytostatic drugs used concomitantly, and the combination alone was less toxic. The high response rate obtained is attributed to a synergistic effect of cis-platin and bleomycin administered for prolonged periods.
Effect of large city conditions on the species composition of fleas parasitizing small mammals.
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Urinary excretion of modified nucleosides in patients with acquired immune deficiency syndrome (AIDS) and individuals at high risk of AIDS.
Patients with certain malignant diseases excrete in their urine elevated levels of modified nucleosides originating from breakdown of transfer RNA (tRNA). A high incidence of acquired immune deficiency syndrome (AIDS), often associated with rapidly progressing Kaposi's sarcoma (KS), is currently being observed in many countries. Male homosexuals are considered to be at highest risk of developing these disorders. We have examined 10 patients with AIDS and 77 male homosexuals without clinical manifestations of AIDS at the time of examination. Elevated levels of modified nucleosides were found in all patients with AIDS. Of further interest was the finding of a high prevalence of abnormal nucleoside levels in the high-risk group, with a trend toward higher levels in those high-risk individuals who had lymphadenomegaly, considered a prodrome of AIDS. These findings indicate that determination of urinary nucleoside levels may help identify individuals at high risk of developing AIDS thereby increasing the possibility for prevention and early therapy.
Screening for vesicoureteral reflux in children using real-time sonography.
One hundred and ten children, ages 6 days to 14 years, were investigated for vesicoureteral reflux (VUR) using ultrasound before voiding cystourethrography (VCU). Sonographically a VUR was assumed if a retrovesical dilated ureter and/or an increase of the separation of the central renal echo complex (CRC) could be detected. By means of sonography VUR grades III and IV were seen in 100%, grade II in 84% of all cases. There was a false positive rate of 10%. Sonographic reflux study is a sensitive and specific screening and follow-up procedure for VUR.
Transfer RNA breakdown products in the urine of asbestos workers.
Patients with malignant mesothelioma, a neoplasia strongly associated with previous asbestos exposure, excrete in the urine high levels of modified purines, pyrimidines, and their ribosides, breakdown products of transfer RNA. The urinary excretion levels of modified nucleosides were measured in 47 male insulation workers with long term exposure to asbestos and, therefore, at high neoplastic risk. The nucleoside levels of 44 male control subjects were used for comparison. Asbestos-related radiographic changes were found in 70% of the exposed individuals. An increasing severity of radiographic alterations was associated with a greater frequency of elevated nucleoside clusters, especially in m'A, m'I, m'G, and m2(2)G. Duration since onset of exposure was directly related to pseudouridine, m'I, and m2(2)G. Though cigarette smoking contributes to the development of asbestos-related lung cancer, data are presented that support the hypothesis that asbestos exposure is the more important factor related to the elevated values of nucleosides. It was concluded, therefore, that measuring nucleoside levels in populations at high risk of developing certain kinds of cancer may provide a useful diagnostic tool for detecting "preclinical" biochemical changes that may be predictive of future neoplastic manifestations.
A patient homebound by panic: understanding and treating agoraphobia.
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