Specificity of a conductance assay for enumeration of Escherichia coli from broiler carcass rinse samples containing genetically similar species.

Experiments were conducted to evaluate the specificity of a rapid method for enumeration of Escherichia coli from fresh broiler chicken carcasses. In three separate trials, E. coli, Citrobacter freundii, Salmonella Enteritidis, and Shigella sonnei were serially diluted and then inoculated into identical broiler chicken carcass rinses. Inoculated rinses were mixed with double-strength Coliform Medium supplemented with 2% dextrose. This mixture was placed in a Bactometer module in duplicate, and conductance was measured at 44 degrees C. Results indicated that C. freundii did not grow to an appreciable degree in the selective medium at 44 degrees C. Salmonella Enteritidis grew similarly to E. coli; however, an initial level of 10(6) Salmonella in the food product would be required for Salmonella to interfere with enumeration of E. coli using this method. S. sonnei grew at a more rapid rate than E. coli; however, there was an interaction between the regression lines formed when serial dilutions (log10 CFU/ml) were compared to E. coli detection times for these two species of bacteria. Therefore, high levels of S. sonnei in a food sample may interfere with the enumeration of E. coli. In general, Salmonella and Shigella are not found at high enough levels on poultry products to interfere with enumeration of E. coli using this method and, if found at high levels, would be detected and rejected using this procedure. Hence, the presence of organisms that are genetically and phylogenetically similar to E. coli would not preclude enumeration of E. coli using conductance under these conditions.

Evaluation of a conductance method for enumerating Escherichia coli on chicken, pork, fish, beef, and milk.

Experiments were conducted to evaluate a rapid method for enumerating Escherichia coli on food products of animal origin. In study I, rinses from samples of chicken, ground beef, pork, and fish and samples of milk were inoculated with various levels of actively growing E. coli. Conductance assays were monitored at 44 degrees C on each sample using coliform medium supplemented with 2% dextrose. High correlations between E. coli concentrations and E. coli conductance detection times (ECDTs) were found (r = -0.97 to -0.99) for all foods tested in all replicates; however, in most cases, the concordance correlation coefficients (r(c)) were low, indicating a lack of predictive accuracy. In this study, low accuracy of the conductance method for estimating E. coli counts was attributed to use of concentrations of E. coli that exceed 10(6) CFU/ml, the detection threshold of the instrument. Slopes of the linear regression lines (E. coli concentration vs. ECDT) for each type of food tested were not significantly different (P < 0.0001), indicating that a single regression equation may be used to estimate E. coli counts for all of the types of food tested in 1 to 7.5 hours using ECDT. In study II, ECDTs for pork, fish, beef, and milk significantly (P < 0.05) decreased in a linear manner as time of temperature abuse increased. Although the ECDT for chicken decreased linearly, no significant differences were observed between 3 and 6 or between 9 and 12 h of abuse. These data demonstrate a strong relationship between increasing populations of E. coli due to temperature abuse and decreasing ECDT. Therefore, results from both studies indicate that this method could be useful for estimating naturally occurring populations of E. coli on foods of animal origin.

A rapid microbiological method for enumerating Escherichia coli from broiler chicken carcasses.

Experiments were conducted to evaluate a rapid method for enumerating Escherichia coli from broiler chicken carcasses. In three separate trials, carcasses were obtained from a commercial processing plant, temperature abused at 37 degrees C for 0, 3, 6, 9, or 12 h, and then rinsed. E. coli were enumerated from carcass rinses using Petrifilm E. coli count plates (PC) and by placing the rinse into double-strength colifiform medium supplemented with 2% dextrose (CMD). The CMD mixture was placed into a Bactometer module and conductance was measured at 44 degrees C. Once a detection time (DT) was recorded, the sample was immediately recovered from the module well, diluted, and spread onto plate count agar. Colonies on plates at the highest dilution from each module well were randomly selected and identified. After 0, 3, 6, 9, and 12 h of temperature abuse, E. coli was the bacterial species identified 97, 92, 88, 87, and 61% of the time, respectively. These results indicate that the medium/temperature combination was excellent for enumerating E. coli from samples that contain mixed microflora using conductance. Significant linear correlations were observed between time of abuse (TA) and log10 PC (LPC) or DT (R2 = 0.86 and R2 = -0.90, respectively). A significant linear correlation was observed between LPC and DT (R2 = -0.92). This rapid method (1 to 7.6 h) for enumeration of E. coli on chicken should provide a way to determine E. coli levels before a product is shipped, and it should aid the poultry industry in meeting the E. coli testing requirement of the U.S. Department of Agriculture Food Safety and Inspection Service pathogen reduction regulation.

Using a symbiotic man/machine approach to evaluating visual clinical research data.

Some candidate medical expert system applications have a significant visual component. Knowledge engineers usually dismiss such task domains as potential expert systems applications. Our success in developing ESCA, a system for evaluating serial coronary angiograms, shows that such task domains should not be dismissed so quickly. We used a symbiotic approach between man and machine, where technologists provide the visual skills with an expert system imitating the conceptual skills of the expert, to produce a partially automated system that is more consistent and cost effective than one that is fully manual. The agreement between the system's conclusions and that of a panel of experts is good. The expert system actually has a slightly higher agreement rate with the expert panel than the agreement rate between two expert panel teams evaluating the same film pair.

Immunopathologic and clinical studies in pulmonary hypertension associated with systemic lupus erythematosus.

PH is an uncommon manifestation of SLE. The symptoms of PH develop within a few years after the onset of the multisystem disease. The most common presenting complaints of SLE patients with PH are dyspnea on exertion, chest pain, nonproductive cough, edema, and fatigue or weakness. The important physical findings are a loud second pulmonic heart sound and a right ventricular lift. The chest roentgenogram shows a cardiomegaly, a prominent pulmonary segment, and usually clear lung fields. Pulmonary function tests may show evidence of restrictive lung disease; however, the physiologic abnormalities are mild and out of proportion to the severity of the PH. The diagnosis of PH is established by cardiac catheterization showing elevated pulmonary artery pressure, normal capillary wedge pressure, and no evidence of intracardiac or extracardiac shunts. Pathologic examination of the lung demonstrates angiomatoid lesions involving muscular pulmonary arteries. There is a thickening of the media and subintima of the arterioles. Immunoglobulin and complement deposits are found in the walls of pulmonary arteries. Immunoglobulin eluted from the lung contains rheumatoid factor and antinuclear antibody including antibody to DNA activity. DNA antigen is also present in walls of blood vessels. These results suggest an immune complex deposition process as a mechanism in the pathogenesis of PH in SLE. The clinical course of PH in SLE is variable. Symptoms may be mild and the disease follows a stable and protracted course for several years. It can, however, develop a progressive course ending in death in a few years. The clinical response of SLE patients with PH to treatment with high doses of systemic corticosteroids is not consistent or predictable.

Studies on the origin of androstanediol and androstanediol glucuronide in young and elderly men.

The in vivo origin of androstanediol (3 alpha diol) and its glucuronide was studied in six young and five elderly men undergoing cardiac catheterization. Constant infusions of [14C]testosterone and [3H]3 alpha diol were given, and blood was obtained from the aorta and hepatic vein in order to measure metabolic clearance, splanchnic extraction, and the possibility of splanchnic production of both 3 alpha diol and its glucuronide. In young elderly men, the concentrations of labeled and unlabeled testosterone, dihydrotestosterone, and 3 alpha diol were lower in the hepatic vein than in the aorta. The specific activities of dihydrotestosterone and 3 alpha diol were the same in blood entering and leaving the splanchnic compartment. The plasma concentration of 3 alpha diol was 18 +/- 2 in the young men and 15 +/- 4 ng/dl in the elderly group. However, the blood production rate of 3 alpha diol determined from the metabolic clearance and morning plasma concentration was reduced (324 vs. 199 micrograms/day) as a result of lower clearance in the elderly men. Plasma 3 alpha diol glucuronide concentrations were 197 +/- 68 and 96 +/- 35 ng/dl in the two groups. No difference in the concentration of 3 alpha diol glucuronide was observed across the splanchnic tissues by mass, radioactive levels, specific activity, or 14C to 3H ratios. The 14C to 3H ratio for 3 alpha diol glucuronide was 10 times higher than for the free steroid, indicating that more than 90% of the glucuronide originates from a pool separate from blood 3 alpha diol. Both the splanchnic extraction of 3 alpha diol and the metabolic clearance were reduced in elderly men. These studies indicate that both 3 alpha diol and its glucuronide in blood result from extrasplanchnic events. A major reduction in the plasma concentration of 3 alpha diol glucuronide occurs in the aging male, although no difference is seen in the levels of the unconjugated 3 alpha diol. 3 alpha diol and its glucuronide are derived principally by extrahepatic (target) tissue events.

Alteration in the metabolism of dihydrotestosterone in elderly men with prostate hyperplasia.

In vivo androgen kinetics were determined in six young (21--49 yr) and elderly men (62-77 yr) with prostatge hyperplasia (BPH). Steady-state infusions of [14C]testosterone and [3H]androstanediol (3 alpha diol) were given, which allowed determination of the conversions testosterone leads to dihydrotesterone (DHT) in equilibrium or formed from 3 alpha diol. These infusions also yield metabolic clearance data which, together with meaurement of nonisotopic steroid levels, yield estimations of blood production rates. The production rate for testosterone was 6.04 +/- 1.66 vs. 3.69 +/- 0.62 mg/d, whereas the production rate for 3 alpha diol was 319 +/- 57 and 193 +/- 34 micrograms/d (P < 0.05 both groups). The irreversible conversion rate of testosterone to DHT was 3.1 +/- 0.4 and 3.5 +/- 0.9% (NS). The back conversion of 3 alpha diol to dHT was high (68 +/- 25 vs. 81 +/- 17, NS) indicating that 3 alpha diol might cause BPH as a result of conversion to DHT in vivo. The conversion of DHT to 3 alpha diol is reduced in the elderly group (15.8 +/- 2.6 and 6.3 +/- 1.4, P < 0.001). Since DHT formation in the prostate is a key event in the development of BPH and blood DHT appears to be a measure of extrasplanchnic sexual target tissue activity, our in vivo studies suggest that the tissue increase in DHT may result from reduced metabolism and the activity of 3 alpha-oxidoreduction favors the oxidative pathway in elderly men.

Direct conversion of testosterone to dihydrotestosterone glucuronide in man.

Tritiated testosterone and [14C]dihydrotestosterone (DHT) were administered by constant iv infusion into five young and five elderly men undergoing diagnostic cardiac catheterization. The radioactivity concentrations of free and conjugated DHT in arterial and hepatic vein blood samples were then determined. The analysis of the 3H:14C ratio of free DHT in arterial and hepatic vein blood showed that in both groups, the 3H:14C ratio of free DHT was the same in arterial and hepatic vein blood, indicating that splanchnic tissue is not the source of blood DHT from testosterone. This is in agreement with data that the transfer constant across the liver ([rho]T-DHT SD) was undetectable. In both young and elderly men, a significant increase of the 3H concentration of DHT glucuronide in hepatic vein blood was observed, indicating that the splanchnic compartment could be the site of production of DHT glucuronide. The 3H:14C ratio of DHT glucuronide was much higher than that of free DHT in both groups, suggesting that DHT glucuronide is derived from the blood testosterone pool, and most of the DHT from testosterone seems to be conjugated before mixing with blood DHT. This study indicates that a large fraction of DHT produced in the liver from testosterone is efficiently conjugated or further metabolized, and this results in the lack of splanchnic production of free DHT in men.