RENEX: an expert system for the interpretation of 99mTc-MAG3 scans to detect renal obstruction.

A renal expert system (RENEX) has been developed to assist physicians detect renal obstruction in patients undergoing pre- and postfurosemide 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) scans. RENEX uses quantitative parameters extracted from the dynamic renal scan data and heuristic rules in the form of a knowledge base (KB) obtained from expert interpreters to conclude whether a kidney is obstructed. METHODS: Normal limits were established for 47 quantitative parameters extracted from the 99mTc-MAG3 scans of 100 potential renal donors. From these data the domain expert estimated 5 boundary conditions for each parameter: (i) definitely abnormal, (ii) probably abnormal, (iii) equivocal, (iv) probably normal, and (v) definitely normal. A sigmoid-type curve was then generated from these 5 boundary conditions, creating a parameter knowledge library used for converting the value of a prospective patient's individual quantitative parameters to a certainty factor (CF). Sixty heuristic rules were extracted from the domain expert to generate the KB for detecting obstruction. A forward-chaining inference engine was developed using the MYCIN combinatories (an approximation of Bayes theorem) to determine obstruction. A justification engine was implemented, which recorded the sequence of each rule that was fired and the current CF value of all input and output parameters at the time of instantiation to track and justify the logic of the conclusions. The entire system was fine tuned and tested using a pilot group of 32 patients (11 males, 21 females; mean age, 56.8 +/- 17.2 y; 63 kidneys) deemed by an expert panel to have 41 unobstructed kidneys, 13 obstructed kidneys,and 9 equivocal findings. RESULTS: RENEX agreed with the expert panel in 92% (12/13) of the obstructed kidneys, 93% (38/41) of the unobstructed kidneys, and 78% (7/9) of the kidneys interpreted as equivocal for obstructions. Processing time per patient was practically instantaneous using a 3.0-GHz personal computer programmed using interactive data language. CONCLUSION: We have developed a renal expert system for detecting renal obstruction using pre- and postfurosemide 99mTc-MAG3 renal scans, at a standardized expert level. These encouraging preliminary results warrant a prospective study in a large population of patients with and without renal obstruction to establish the diagnostic performance of this system.     

Pancreatic pseudocysts: Cause, therapy, and results

Sixty-nine patients with pancreatic pseudocysts were reviewed. Chronic alcohol abuse was associated with pancreatitis in 78 percent of the patients. Presenting signs and symptoms were nonspecific. Ultrasonographic and computerized axial tomographic scans were most commonly used to established the diagnosis. Twenty patients were managed conservatively and resolution occurred in 11 of these patients. Forty-nine patients underwent operation. Internal drainage was performed on 31 occasions in 29 patients, and external drainage was performed in 11. In addition, pancreatic resection was carried out in 8 patients, and needle aspiration in 2 patients. Infected pseudocysts were present in 11 patients. Complications occurred in 18 patients in the operated group and 2 patients died (4 percent). There was recurrence of pseudocysts in 10 patients. Our results suggest that pseudocysts remain a common complication of pancreatitis, and infected pseudocysts are the major cause of postoperative morbidity. Computerized axial tomography and ultrasonography are the mainstays of diagnosis. Surgical therapy is safe, but continues to be associated with significant rates of morbidity and recurrence. When pseudocysts recur, they are generally anatomically distant from the original lesion and probably represent new disruptions of the pancreatic duct.     

Endometrial expression of vasopressin, oxytocin and their receptors in patients with primary dysmenorrhoea and healthy volunteers at ovulation

OBJECTIVE: To investigate gene expressions for neurohypophyseal and ovarian hormones as well as their receptors in the endometrium of women with primary dysmenorrhoea and healthy subjects at ovulation. STUDY DESIGN: A group of eight women with moderate to severe dysmenorrhoea and eight healthy subjects were compared in parallel between 18 and 35 years of age, regularly menstruating, non-overweight and nulliparous. The study was performed at The Department of Obstetrics and Gynecology, University Hospital of Lund, Sweden. Endometrial biopsies were taken around the time of ovulation, which was determined by repeated ultrasound examinations. Receptor and gene expressions for oxytocin and vasopressin in the tissue were measured. RESULTS: The gene expression for oxytocin receptor was significantly lower in dysmenorrhoic than in healthy women, in median 1.21 and 3.44 oxytocin-receptor/actin, respectively (p=0.048). The expressions for oxytocin peptide, vasopressin V1a receptor, oestrogen receptor alpha, beta and progesterone receptor did not differ between the two groups. Expression of vasopressin peptide was not detectable. CONCLUSION: A lower oxytocin receptor gene expression at mid-cycle could be involved in the aetiology of primary dysmenorrhoea. However, the importance of a paracrine effect of oxytocin and its receptor at ovulation warrants further investigation.     

STUDIES ON EXPERIMENTAL PNEUMONIA : IX. PRODUCTION IN MONKEYS OF AN ACUTE RESPIRATORY DISEASE RESEMBLING INFLUENZA BY INOCULATION WITH BACILLUS INFLUENZ?.

Twelve normal monkeys inoculated on the mucous membranes of the nose or nose and mouth with a strain of Bacillus influenzæ; originally isolated in pure culture from the pleural exudate of a case of empyema following influenzal pneumonia in man and subsequently raised in virulence by animal passage, developed an acute self-limited respiratory disease of from 3 to 5 days duration, characterized by sudden onset with profound prostration, the development of rhinitis and tracheobronchitis, with sneezing, cough, and the outpouring of a scanty mucoid, or mucopurulent exudate, a variable febrile reaction, and either a leucopenia or no significant change in the leucocyte count. This disease was complicated in five instances by purulent sinusitis of one or both antra, in three by bronchopneumonia. Bacillus influenzæ was recovered at autopsy from the lesions of the disease either in pure culture or in association with organisms that are normal inhabitants of the upper respiratory tract of monkeys. Of ten normal monkeys injected intratracheally with the same strain of Bacillus influenzæ, seven developed bronchopneumonia, two developed tracheobronchitis without pneumonia, and one resisted infection. The general symptoms and duration of the disease were similar to those of the preceding group. There were a severe cough and accelerated respirations. Bacillus influenzæ was recovered in pure culture from the lungs, bronchi, or trachea in the animals killed during the active stage of the disease. It disappeared promptly from the respiratory tract with recovery. The significance of the first series of experiments in which monkeys were inoculated in the upper respiratory tract is twofold. First, they establish the fact that Bacillus influenzæ can initiate in monkeys an acute infection of the normal mucous membranes of the upper respiratory tract; that is, it can act as a primary incitant of respiratory infection without the assistance of a preceding or concomitant contributing cause. In this respect it differs radically from the pneumococcus and Streptococcus hæmolyticus, since experiments previously reported^{2, 4} have shown that neither of these organisms possesses the property of initiating an infection of the normal mucous membranes of the upper respiratory tract of monkeys, even though the strains used were incalculably more virulent for monkeys than the strain of Bacillus influenzæ used in the foregoing experiments. Secondly, the experiments show that Bacillus influenzæ infection of the mucous membranes of the upper respiratory tract may spread by continuity to the paranasal sinuses, setting up an acute sinusitis, that it spreads readily to the lower respiratory tract, producing a tracheobronchitis and permitting the ready invasion of secondary bacteria, and that it may penetrate as far as the terminal bronchioles, alveolar ducts, atria, and alveoli, there setting up a bronchiolitis and true bronchopneumonia. In these respects it likewise differs radically from the pneumococcus and Streptococcus hæmolyticus which do not possess these pathogenic properties as previous experiments have shown.^{2, 4} The bearing of these facts on the possible etiologic relation of Bacillus influenzæ to influenza is important, since they show that Bacillus influenzæ possesses certain definite primary pathogenic properties which distinguish it and therefore separate it from the group of recognized secondary organisms in influenzal complications, of which the pneumococcus and the streptococcus are the most frequent. The possible etiologic relation of Bacillus influenzæ to influenza is further supported by the character of the respiratory disease that occurred in the monkeys. The sudden onset with profound prostration, the absence of leucocytosis or often a leucopenia, the congestion of the mucous membranes of the respiratory tract, the development on the 2nd or 3rd day of an irritative cough due to an inflammatory tracheitis or tracheobronchitis, the brief self-limited course of the infection, and the irregular febrile reactions are all characteristic of influenza. Many of these symptoms were in striking contrast with the symptoms and course of pneumococcus or streptococcus infections in monkeys in which there were no prostration at onset, invariable leucocytosis, and infrequent cough developing only late in the disease. While all the above features of the disease produced in monkeys are characteristic of influenza in man, none are pathognomonic and, in fact, it is doubtful whether uncomplicated influenza possesses any pathognomonic features by which it may be diagnosed certainly in the absence of an epidemic. Even during epidemic times many respiratory infections arise which, though presumably influenza, it is impossible to diagnose as such with certainty. Nor does pathology help in this respect, since there would appear to be no established distinctive lesions of uncomplicated influenza in man, nor for that matter of the complications of influenza, apart from the complications which have been ascribed by Pfeiffer,⁵ MacCallum,⁶ Wolbach,⁷ and others to infection with Bacillus influenzæ because of the association of Bacillus influenzæ in pure culture with these complications. For these reasons, although the disease produced in monkeys appears to be essentially identical with influenza in man with respect to its clinical course and complications, it is impossible to determine certainly whether it is actually so. The experiments are advanced, therefore, as evidence in favor of the etiologic relation of Bacillus influenzæ to influenza, though they do not permit of a definite conclusion in this respect. Their bearing upon the relation of Bacillus influenzæ to certain of the complications of influenza would appear to be reasonably conclusive. The recovery of Bacillus influenzæ in pure culture at autopsy from the antra, from the trachea and bronchi, and from the lungs in some of the animals developing sinusitis, bronchiolitis, and a characteristic type of bronchopneumonia confirms by animal experiment the etiologic relation of Bacillus influenzæ to these complications of influenza, which hitherto has rested solely upon the frequent association of the influenza bacillus with these lesions in man. The production of tracheobronchitis and the same type of bronchopneumonia by the intratracheal injection of Bacillus influenzæ in the second series of experiments serves as additional confirmation of this, but has no direct bearing on the etiologic relation of Bacillus influenzæ to uncomplicated influenzæ.