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Biomedical subjects

N Chau

Publications and source records attributed to N Chau.

At least 55 records · Page 3Linked to original sources
PubMed1986

A longitudinal study of symptoms and respiratory function tests in iron miners.

A first survey has been conducted on 1179 iron-ore mine workers, 35-55 years old, who were randomly selected from 5900 at work with normal chest roentgenograms. Five years later, 871 of them were re-examined. Both surveys included a standard respiratory symptoms questionnaire (British MRC), a physical examination of the chest, and measurement of pulmonary function (vital capacity - VC; forced expiratory volume during 1 s - FEV1.0; residual volume - R.V. by helium dilution: carbon monoxide uptake - FuCO by the steady-state method). Both surveys were done by the same research team under identical conditions, using the same equipment. The mine technical services determined the dust and noxious gas concentrations at work places. No evidence of worsening of respiratory health status was observed overall. Symptoms of chronic bronchitis and asthma were recorded with a similar prevalence in both surveys; the decline in lung function was minimal for the total sample. However, our aim was to compare changes that were observed in groups differing by work place (surface or underground) or by activity (active or retired). Analysis showed that development of respiratory symptoms was more frequent and decline in lung function accelerated in the 5-year interval among underground workers who were still active as compared to those retired. In all subgroups (surface or underground workers, active or retired), decline of lung function values was more marked in smokers compared to non-smokers.

Adult↗
PubMed1985

A longitudinal study of pulmonary function in coal miners in Lorraine, France.

A longitudinal study of pulmonary function and radiological change has been conducted on 141 nonsmoking coal miners and 256 smoking coal miners from Lorraine, France. At the time of the first examination occasioned by radiological change or shortness of breath, the men averaged between 46.6 years and 50.9 years of age, and they retired approximately 8 years after entering the study. They have been followed for average periods of about 18 years and a mean of five FEV1 observations per man were made over that period. Changes in radiological category have been documented. Average rates of decline of FVC and FEV1 were similar, and varied between -47 ml/yr in nonsmoking miners still alive, to -78 ml/yr in deceased smoking miners. These accelerated rates were similar before and after retirement from the mine.

Age Factors↗
PubMed1985

[Conception of a program for the treatment and statistical interrogation of data, LOGIST].

This paper presents a general program which cannot only be used for the treatment and the statistical interrogations, but also for basic operations, such as the validity check and the preparation of data which is often necessary for other programs. Its use of language is simple, suitable and accessible to non-specialists. The program is sufficiently complete so that it can treat some complex problems without requiring complementary programs. It can treat several problems simultaneously. This allows one to gain data-reading time and the program is therefore economical. Its domain of use is large: epidemiological studies, psychological and sociological investigations, biological studies, clinical research, chronological follow-up, examinations of faculties, . . . . The program is written in FORTRAN IV and thus transferable. It contains more than 25 000 instructions but needs limited place in the core memory (less than 64 000 words). Its structure allows further evolution and addition of new procedures or new methods. A transformation into a conversational form is considered.

Computers↗
PubMed1985

"ESVITAF". Survey on the vitamin status of the French: relationships between nutrient intake and biochemical indicators.

The relationships between dietary data and biochemical nutritional status for vitamins B1, B2, A, E, beta-carotene, folic acid and iron have been studied using data from a survey conducted on 710 adults. Significant correlations were found between riboflavin intake and biochemical values for males only (r = -0.105, p less than or equal to 0.05), between beta-carotene intake and plasma beta-carotene (r = 0.232, for males and r = 0.292 for females, p less than or equal to 0.001), and between iron intake and plasma iron for males only (r = 0.115, p less than or equal to 0.05). Concerning nutrient densities, correlations were significant between dietary riboflavin and biochemical measure (r = 0.163, p less than or equal to 0.01 for males, r = -0.135, p less than or equal to 0.05 for females), between vitamin A intake (expressed in retinol equivalent) and beta-carotene (r = 0.212, p less than or equal to 0.001 for males, r = 0.157, p less than or equal to 0.01 for females) and for males only, between dietary iron and hemoglobin (r = 0.144, p less than or equal to 0.01). The dietary data for each nutrient were examined for their sensitivity, specificity and predictive values in identifying subjects with substandard or overstandard biochemical values. For all nutrients the positive predictive value percentage was always below 25%, the negative predictive value percentage always under 75%.

Adolescent↗
PubMed1984

Prognostic value of acetylcholine challenge test: a prospective study.

Eleven hundred and nine iron mine workers aged 35 to 55 with normal chest radiographs were submitted to a pulmonary examination consisting of a questionnaire, a clinical examination, and pulmonary function testing including an acetylcholine challenge test. A positive response (decrease of FEV1 of more than 10%) was observed in 210 subjects (Ace+). The remaining 899 had a negative response (Ace-). Bronchitis, asthma, dyspnoea, and obstructive syndrome were more frequent in the Ace+ group. Five years later, 820 subjects were reexamined: occasional cough and sputum and chronic bronchitis appeared more frequently among subjects without symptoms at the first examination but with a positive acetylcholine challenge test. The obstructive syndrome was more often observed and regressed more rarely in the Ace+ group. The results confirm the use of a test of bronchial hyperreactivity as a means of identifying subjects at risk from chronic obstructive lung disease.

Acetylcholine↗
PubMed1984

Reduction of pulmonary function indices: comparison of two hierarchical methods.

From tests for evaluating pulmonary function many indices may be calculated. In order to reduce their redundancy, two hierarchical methods for selecting the most significant indices are applied to data collected on a group of 228 firemen. The first method consists in a stepwise linear discriminant analysis which selects the indices according to their discriminant value for distinguishing between asymptomatic and symptomatic subjects. The second one is derived from a stepwise multiple correlation procedure, which selects the indices on the basis of their linear relationships. These two methods lead to different results and the choice between them should be made according to the aims intended for data reduction.

Adult↗
PubMed1983

[Method of file sorting for mini- and microcomputers].

The authors describe a new sorting method of files which belongs to the class of direct-addressing sorting methods. It makes use of a variant of the classical technique of 'virtual memory'. It is particularly well suited to mini- and micro-computers which have a small core memory (32 K words, for example) and are fitted with a direct-access peripheral device, such as a disc unit. When the file to be sorted is medium-sized (some thousand records), the running of the program essentially occurs inside the core memory and consequently, the method becomes very fast. This is very important because most medical files handled in our laboratory are in this category. However, the method is also suitable for big computers and large files; its implementation is easy. It does not require any magnetic tape unit, and it seems to us to be one of the fastest methods available.

Computers↗
PubMed1983

[Long-term prognosis of chronic bronchitis following the first episode of acute respiratory decompensation].

In order to assess the prognosis significance of the first episode of acute respiratory failure in chronic bronchitic, 100 bronchitics experiencing an episode of failure were followed for 3 1/2 to 6 years. A multivariate statistical analysis revealed the best prognostic parameters: the FEV1 (VEMS), the steady state Co transfer, age, neuro-psychiatric signs of respiratory failure and supra-ventricular dysrhythmias on ECG. Normocapnia contributes to a stabilised respiratory state. A predictive value could not be established for the clinical signs of right ventricular failure and of right ventricular hypertrophy on the ECG. Cardio-respiratory failure is the dominant cause of death but other causes occur more frequently in those subjects with severe respiratory impairment.

Acute Disease↗
PubMed1982

[A chronological linkage technic of records and use of the obtained information. Application to the functional control of cardiac stimulators].

The application of information processing to the study of the evolution of the patient's state requires the constituting of a file which contains the values of different items as functions of time. There are many methods for doing this and most of them appeal to the construction of a complex database. The technique presented in the paper paper tries at first to constitute, for each patient, some records, of which every one corresponds to a determined "operation' (the term "operation' is taken in the wide sense; example: consultation, surgical intervention,...) then to link them according to the chronological order. It has the advantage of being easy so that it may be used even on minicomputers. Furthermore, the exploitation of the resultant data file is very easy. This method is well suited to problems such as the examination of the longitudinal investigations, the treatment of records of the patients who went through several operations, etc. The application presented here is the checking of the functioning of pacemakers. We wrote on a minicomputer MITRA 15/125 transferable general program (using FORTRAN IV exclusively), which allows one to carry out the linking and to exploit the resultant file. It is so designed that the addition of new procedures involved in new applications may be very easy.

Computers↗
PubMed1981

[A study of the cytotoxicity of chloroform, 1-2-dichloroethane, 1,1,1-trichloroethane and hexachlorobutadiene to mouse L cells (author's transl)].

A cytotoxicity test based on residual protein determination is described and the in vitro toxicity of certain chlorinated aliphatic hydrocarbons is evaluated with this test. The results obtained are sufficiently reproducible to yield an order of cytotoxicity: hexachlorobutadiene is about 100-fold more toxic than chloroform or 1,2-dichloroethane; whereas, 1,1,1-trichloroethane is 10-fold more toxic than these two compounds. The method is fast and lends itself to the toxic evaluation of large numbers of samples.

Animals↗
PubMed1980

Concept and implementation of a program for treatments and statistical or logical interrogations of a file: LOGIST.

LOGIST is a general program which can be used for the usual statistical interrogations and also for other basic operations such as a validity check, the transcoding and the listing of data essential to biomedicine and the human sciences. The objectives laid down for this program have enabled almost total transferability (using FORTRAN IV exclusively), simplicity in the interrogation language, clear presentation of results, reduction to a minimum of computer running time and working storage required and the facility for modification of program or addition of new sub-programs. All the possible statistical procedures have not been included yet but any such additions are quite simple. This program, despite its considerable size, can be satisfactorily used on a mini-computer. At present, it is installed on a Mitra 15 computer with a total memory capacity of 32 K words of 16 bits. Use with larger more powerful machines will increase its potential. Routine application to diverse problems (quality control of a file, transcoding, linking of data, etc....) is very satisfactory.

Computers↗
PubMed1980

[The different ways of expressing the results of the monoxide test in steady state: discussion and proposition of reference values for epidemiological studies (author's transl)].

The results of the steady state carbon monoxide test can be expressed quantitatively as the amount of CO absorbed by the lung per minute and per 1 mm Hg pressure difference (TCO; ml/min/mm Hg) or as the ratios between partial pressures of CO (FICO, FECO, FACO), fractional untake coefficient (Formula: see text), From measurements taken in 141 non-smokers (mean age 47.43 +/- 6.4 years), 60 ex smokers (mean age 45.73 +/- 5.29 years) and 322 smokers (mean age 46.65 +/- 5.5 years), TCO and fractional uptakes were calculated and discussed. Considering the fact that mean TCO had a larger standard deviation that mean FUCO and that TCO had a non-Gaussian distribution, the authors chose to express the results of the test in fractional uptakes. Equations are proposed to calculated fractional uptakes.

Adult↗
PubMed1978

[Comparison of the cytotoxicity of chloroform on mouse L cells by measurement of proteins and chromium 51 release].

The authors describe a new cytotoxicity test based on the classical measurement of the residual proteins after a contact time of 4 days between the produit tested and the mouse L cells. The results are expressed as a cytotoxic dose 50 with a confidence limit for the 95% threshold after a statistical treatment of the analytical data by a computerized method. For chloroform, this method is more sensitive that the classical cytotoxicity test involving the chrom 51 release.

Chloroform↗
PubMed1977

A new display technique for computer-processed digital scans.

This article presents a new approach for presenting scintigraphic images. The technique combines the conventional plotting the contour lines and the highlighting, by means of hatching, of the concavities (or convexities) of the 'surface' representative of radioactive distribution. The search for the surface features is achieved generally by the method of normal curvatures. An example with a phantom demonstrates the utility of this representation method.

Computers↗