Comparative study of human expertise and an expert system: application to the diagnosis of child's meningitis

We present a general method of statistical evaluation for expert systems, applied to a system for the diagnosis of child's meningitis. Fifty difficult clinical cases of child's meningitis were submitted to the system, to seven senior specialists and to seven young physicians. Multidimensional analysis of the diagnosis of the infection category reveals that the two groups of physicians separate naturally and that the system is located among the group of experts. The study of the agreement of the microbiological diagnosis and therapeutic advice shows that the advice of the two groups of physicians is significantly different and that the advice of the system is significantly closer to that of the experts. This result is confirmed by the study of therapeutic errors. This type of study allows one to classify the performance of the system among physicians having different levels of expertise without referring to an objective solution.

[Acute pyelonephritis in children]

In children, pyelonephritis (or upper urinary tract infection) exposes to systemic complications and renal sequelae. The diagnosis rests on cytobacteriological examination of urine, but its results are difficult to interpret in neonates and small infants due to the possible contamination of urine collected in bags. It is recommended to repeat samplings in order to confirm a positive result or to collect the urine by a reliable technique such as puncture of the bladder. In 50% of the cases urinary infection reveals a urinary tract abnormality to be localized in all cases by ultrasonography and cystography completed, if there is any doubt, by intravenous urography. In infants younger than 18 months antibiotic therapy consists of a third generation cephalosporin administered, jointly with an aminoside, by the parenteral routes for at least 10 days. Older children with a better tolerance of the infectious syndrome may be treated with a betalactam antibiotic (amoxicillin-clavulanic acid or cephalosporin) injected alone or with cotrimoxazole administered orally. The effectiveness of treatment is tested by a bacteriological examination of the urine 48 hours after the end of therapy. Antibiotic prophylaxis to avoid recurrences is prescribed after the curative treatment until cystography is performed.

Long-term effects on the thyroid of irradiation for skin angiomas in childhood

Thyroid morphological and functional tests were carried out on 396 patients who were recalled because their thyroid gland had been exposed during hemangioma irradiation in childhood 11-43 years before (median, 22 years). The irradiations have been classified into two categories based on their duration: short duration, from a few seconds to a few minutes (90S and X rays), and long duration, from 30 min to several hours (336Ra, 192Ir, and 32P). The risk of a thyroid nodule increased significantly with the total dose received by the thyroid; it was linked to the dose delivered in the short duration (excess relative risk per Gy = 10), but not to that delivered in the long duration. The risk of a simple diffuse goiter, which also increased with the dose received by the thyroid, did not depend on the duration of the irradiation. In conclusion, this study emphasizes the role of the dose rate in the risk of thyroid nodule, the detection of which does not appear to be improved by plasma thyroid marker determination.

[Mortality in an intensive care unit: predictive value of APACHE II severity score versus maximum APACHE]

Patients admitted to intensive care units (ICU) experience constant changes in their general condition. Therefore, the determination of Apache score within the first 24 hours of admission may not be a reliable index of severity. The aim of this study was to measure daily Apache scores in ICU patients, and to determine if the maximum score (Maximum Apache) attained during hospitalization had a better prognostic value than that of admission. We measured daily Apache scores to 314 patients admitted to Hospital Clínico UC ICU. Mean admission score was 17.5 +/- 9.3 (range: 1-47) and mean maximum score was 18.6 +/- 9.7 (range: 1-47), p < 0.001. Mortality during ICU stay was 17.2%, and 8.6% during hospitalization after ICU discharge. Only 78.3% of patients attained their maximum apache score during the first 24 hours of admission, whereas 21.7% attained it during the rest of ICU hospitalization. Excluding subjects with less than one day of ICU stay, 33% of patients attained maximum Apache score after 24 hours of ICU admission. Statistical analysis showed that maximum Apache score was a better predictor of mortality than that of admission.

The use of porcine liver (2----3)-alpha-sialyltransferase in the large-scale synthesis of alpha-Neup5Ac-(2----3)-beta-D-Galp-(1----3)-D-GlcpNAc, the epitope of the tumor-associated carbohydrate antigen CA 50

alpha-Neup5Ac-(2----3)-beta-D-Galp-(1----3)-D-GlcpNAc (2) and, alpha-Neup5Ac-(2----3)-beta-D-Galp-(1----3)-beta-D-GlcpNAcOMBn+ ++ were prepared on a large scale by the action of beta-D-Galp-(1----3)-D-GalpNAc (2----3)-alpha-sialyltransferase (partially purified from porcine liver) on beta-D-Galp-(1----3)-D-GlcpNAc and beta-D-Galp-(1----3)-beta-D-GlcpNAcOMBn, respectively. The trisaccharide 2 is the epitope of the tumor-associated carbohydrate antigen CA 50, highly expressed in human pancreatic adenocarcinoma.

Epidemiological evidence for a common mechanism for neuroblastoma and differentiated thyroid tumour

Because genetic predisposition probably plays an important role in the aetiology of most of childhood cancers, studies of second primaries occurring after these cancers may be particularly informative about possible common genetic mechanisms in both of these cancers. We have studied the incidence of thyroid tumours occurring after cancer in childhood in a cohort of 592 children treated before 1970. Among these children, six later developed a thyroid carcinoma, and 18 developed a thyroid adenoma. Radiation doses received to the thyroid by each of the irradiated children have been estimated using individual radiotherapeutic technical records. Thyroid carcinomas and thyroid adenomas were five times more frequent after irradiation for neuroblastoma than after irradiation for any other first cancer. This ratio did not depend on sex, nor on time elapsed since irradiation, nor on dose of radiation received for the thyroid gland. This result suggests that there is a common mechanism for the occurrence of neuroblastoma and of differentiated thyroid tumour.

Formulas for threshold computations

Given a continuous variable S, which density functions on two subgroups omega + and omega - of a population omega are known (with for instance a higher mean value on omega + than on omega -), we first define two strategies for classification in these groups; the first one (MWC) consists in determining a threshold alpha such that classifying in omega + when S greater than or equal to alpha, in omega - otherwise, leads to the highest percentage of well-classed elements. The second one consists in choosing the most probable group, given the observed value of S. We give mathematical formulas for the thresholds involved in these two strategies when the density functions, determined by the application of the maximum entropy principle, are those of normal distributions. These formulas prove that the two considered strategies are frequently equivalent, and we give simpler formulas when the partial variances of S on omega + and omega - are unknown or approximately equal. All the formulas are adapted to the case where a cost coefficient is introduced to display the unequal seriousness of the two possible errors (misclassification in omega + or omega -). Then we consider an example, where we see that the computed thresholds can be graphically validated from empirical curves and have the same performances on the learning sample and on a test sample.

Long-term effects in skin and thyroid after radiotherapy for skin angiomas: a French retrospective cohort study

To evaluate the long-term effects of skin angioma irradiation, a recall programme was established which included the systematic recalculation of the radiation dose to the skin and the thyroid. 22% of the 6229 patients contacted had a dermatological examination which revealed cutaneous dystrophy in 81% of the 1137 exposed angiomas and in 39% of the 208 unexposed angiomas. The risk of dystrophy (telangiectasia, hypopigmentation, superficial and subcutaneous atrophy) was 12.1 higher (P less than 0.0001) among patients who had received a surface skin dose above 30 Gy than among those who had received a dose of 10 Gy or less. The relative risk for each dystrophy component increased significantly (P less than 0.001) with surface skin dose. Furthermore, 14 basal cell carcinomas (BCC) were observed in 12 patients from the exposed group for all quantities of radiation, with a mean latency period of 22 years. No BCC was observed for a surface skin dose below 10 Gy. Thyroid testing was done on a subgroup of 431 patients whose thyroid gland had been particularly exposed during angioma irradiation. After recalculation, the dose delivered to the gland was below 1 Gy in 98% of patients. Only 13 thyroid nodules were discovered (1 hot and 12 cold). 1 patient with a cold nodule had a malignant thyroid tumour 21 years after irradiation. He belonged to the group of 7 patients who had received a thyroid dose above 1 Gy. Although no morphological abnormality was found in 98% of the tested patients, most (92%) had a thyroid iodine content below 15 mg (the standard French value), while a raised serum thyroglobulin level (greater than 30 ng/ml) was observed in 17%. This might confer a higher risk of subsequently developing thyroid nodules.

[Treatment of urinary tract infections]

Urinary tract infection (UTI) is common in pediatric age groups and may cause permanent renal damage. Because UTI may occur as the first manifestation of urinary tract malformation, evaluation, of urinary tract morphology should be routine. Variables influencing selection of the most appropriate therapy include the causative organism, location of the infection to the distal and/or proximal urinary tract, severity of constitutional symptoms, age, and history for prior urologic disease. Treatment of pyelonephritis requires bactericidal antimicrobial agents capable of achieving rapid sterilization of the renal parenchyma. Animal experiments have shown that the most effective agents are third-generation cephalosporins and aminoglycosides. Antibiotics are selected on the basis of age and severity of infectious symptoms. In infants under 18 months of age and in patients with severe constitutional symptoms, parenteral administration of both a third-generation cephalosporin and an aminoglycoside is recommended. Patients above 18 months of age who are not severely ill can be given a single oral drug, e.g., a cephalosporin, amoxicillin with clavulanic acid, or cotrimoxazole. Therapy should be continued for ten days in patients with infection of the proximal urinary tract, whereas 5 to 7 days are adequate in patients with cystitis and normal urinary tract morphology.

[Platelet antiaggregants]

Antiplatelet agents are indicated in the prophylactic treatment of certain thromboses, and in particular those due to a complication of atherosclerosis. Acetylsalicylic acid is the best-known, the most commonly used and, probably, the currently most effective agent. The dosage remains controversial; yet, a mean dose of 300 mg daily appears to be recommended nowadays. Ticlopidine and, to a lesser extent, dipyridamole can also be used for this treatment. However numerous contra-indications, such as haemorragic diathesis, surgery and gastric ulcers tend to limit their use. As regards the combination of antiplatelet agents, clinical studies do not show superior efficacy as compared with acetylsalicyclic acid alone.

[Computer-assisted model of weight gain during pregnancy]

The goal of this study was to modelize the evolution of "ideal" weight gain during pregnancy and to generate automatically the appropriate diet. This computerized model has been developed on a microcomputer and has two units: the first unit calculates the "ideal" weight gain during pregnancy, based on the curves of Rosso which show that weight gain is not linear with term and depends of the prepregnancy weight. The second unit calculates the appropriate diet which is depending for the first visit on height, prepregnancy weight and weight gain and for the followed visits on weight gain and the diet situation of the previous visit. The next step will be the medical evaluation of this computer-aided modelization of weight gain during pregnancy.

[Functional result and outcome of total condylar knee prosthesis]

Total condylar knee prosthesis is gradually proving fully reliable. It is an "all or nothing" type of surgery, with either good or bad results depending on the occurrence of complications, notably tibial decementation. With the experience acquired it may be said that the much dreaded wearing off of polyethylene components is not responsible for failures of total knee prosthesis.

[Individualization of X-flavimaculated macular dystrophy in hereditary macular dystrophies]

X-shaped macular dystrophy with flavimaculatus flecks is individualized of other heredo-macular dystrophies. This aspect was showed in two families with a retinal pigment epithelial dystrophy characterised by an X-shaped yellowish macular lesion and numerus flavimaculatus retinal flecks. Nine members were variously affected. The condition was bilateral, had a dominant inheritance, started in middle age with a slow-developing macular lesion. Visual functions were often minimally disturbed for two or three decades. Relations with others here-domacular dystrophy are discussed particularly with pattern dystrophy.

Variables processing in expert system building: application to the aetiological diagnosis of infantile meningitis

We describe a method for the analysis and quantitative synthesis of information in a clinical data file using as an example the aetiological diagnosis of infantile meningitis. The results obtained together with the qualitative knowledge of experts in the field have enabled an experimental system to be constructed. This is performing sufficiently well to be introduced into a hospital environment to assist young doctors facing an emergency situation.

[Meningo-encephalomyelitis in Lyme disease]

A case of isolated central nervous system involvement in Lyme disease is described. A 13 year-old boy developed progressive spastic quadraparesis, chronic lymphocytic meningitis with a low CSF glucose concentration and demyelinating lesions of the white matter on MRI. The diagnosis was proved serologically by high antibody titers against Borrelia burgdorferi (BB) in the serum (1:5, 120) and CSF (1:1,280). There was evidence of specific intrathecal immune response against the BB antigen. The patient was treated with penicillin G and then ceftriaxone. The CSF abnormalities quickly improved but improvement of the neurologic symptoms was gradual and to date still incomplete.

[Results of peripheral retinoschisis treatment in sex-linked congenital retinoschisis]

Overall study of 20 years of curative and prophylactic peripheral retinoschisis treatment in 60 cases of sex linked congenital retinoschisis. Peripheral retinoschisis was present in 36 out of 120 eyes. Twelve eyes of children under 10 years severely affected, have undergone surgery (8 improvements and 4 aggravations) and 21 cases were photocoagulated (18 stabilizations, 3 aggravations which were subsequently treated by surgery). Six cases were not treated. Aggravations after surgery or photocoagulation have always been observed in early postoperative follow-up period. The above findings bring to light the problems of treatment. An epidemiological study of these 60 patients demonstrates that peripheral retinoschisis into bullous phase is only present under 5 years of age with tendency to regress with age (none reported after age of 50). This study corroborates ad absurdum the results of some authors who think that this type of retinoschisis has a tendency to improve spontaneously, and that indications for prophylactic and curative treatment must be thought of very carefully.

[Fusobacterium necrophorum septicemia in an infant]

In a 9 month-old infant admitted to hospital for a fever with chilles, anaerobic blood cultures isolated Fusobacterium necrophorum. On the 5th day of intravenous treatment with amoxicillin and metronidazole clinical signs of mastoiditis, the likely source of the sepsis, became apparent. Septicemias with Fusobacterium necrophorum are usually observed in teenagers and young adults during an acute bout of tonsilitis. This type of infection is exceptional in infants and requires a careful search for a primary focus in facial cavities and in the base of the skull.

[Eye medulloepithelioma. Apropos of 2 cases]

The authors report two cases of medullo-epithelioma of ciliary body found in two young children. They describe the main clinical symptoms which are often non specific (cataract, glaucoma). Diagnosis is based on histological findings following enucleation: the tumor is developed from the ciliary body cells and has often a local malignancy. Metastasis are rare.

Analysis of results in the treatment of peripheral retinoschisis in sex-linked congenital retinoschisis

Curative and prophylactic treatment of peripheral retinoschisis has been studied over a period of 20 years in 60 cases of sex-linked congenital retinoschisis. Peripheral retinoschisis occurred in 36 of 120 eyes. In all, 12 severely affected eyes in children under 10 years of age underwent surgery (8 improvements and 4 aggravations) and 21 cases were photocoagulated (18 stabilisations and 3 aggravations that were subsequently treated by surgery); 6 cases were not treated. Aggravations after surgery or photocoagulation were consistently observed in the early post-operative follow-up period. An epidemiological study of these 60 patients demonstrated that bullous-phase peripheral retinoschisis occurs only in patients under 10 years of age, with a tendency to regress with age (no cases were reported in patients over 50 years of age). This study closely corroborates the findings of authors who think that this type of retinoschisis tends to improve spontaneously and that indications for prophylactic or curative treatment should be very carefully considered.

[The physiology of hemostasis: plasma and tissue factors in coagulation and fibrinolysis]

Coagulation and fibrinolysis are two antagonistic phenomena, the harmonious balance of which results form a perfect regulation of their respective activators and inhibitors. Indeed, the efficacy of the response of the organism to an aggression against the blood vessel and its plasmatic and cellular contents, depends on the capacity of maintaining this balance. The mechanisms involve plasma proteins (factors) endowed with a proteolytic activity, as well as mediators released from injured tissues (endothelium). Coagulation corresponds to the process of fibrin formation (fibrin clump), which assures the consolidation of the platelet clot which was pre-formed during the activation of the platelets. Fibrinolysis consists in the gradual dissolution of this fibrin clump, aimed at re-permeabilization of the vessel at the site of the lesion, and thus at a normalization of the blood circulation at this level. Coagulation and fibrinolysis can hardly be dissociated from primary haemostasis (platelet activation), not only because of their interactions, but also because of their chronology: all these events are, indeed, triggered almost simultaneously, even though the duration varies. The mechanisms that are implicated in thrombo-embolic phenomena are comparable to those of physiological haemostasis. However, it is the imbalance between these events which constitutes the pathological aberration and thus induces the formation of a fibrin-platelet thrombus.