Development of a high-performance liquid chromatography retention index scale for toxicological drug screening

An efficient and practical analytical method for correcting HPLC retention data has been produced using an HPLC diode-array UV detector system. The system is based on retention indices (RI) and is to be used primarily for the identification of toxicologically relevant drugs involved in clinical and forensic toxicology. The RI correction method was chosen as it provided a slightly greater degree of reproducibility than using relative retention time (RRT), particularly for acidic and neutral drugs. Development of the system involved the establishment of the optimal chromatographic conditions and extensive studies of the stability of the system. An acetonitrile gradient elution was used with RI values determined by interpolation from a series of specifically chosen basic and acidic/neutral marker drugs which eluted at regular intervals to produce a linear RI scale. It was found that two separate RI scales were required for basic and acidic/neutral drugs. The use of multiple drug markers as primary retention index standards had not been previously applied to HPLC general drug screening and comparison with a recently published database suggests that the system may also provide improved selectivity.     

High-density morphologies of ice in high-pressure frozen biological specimens

Mouse liver tissue was rapidly cooled by high-pressure freezing at a nominal pressure of 2100 bar. Ultrathin cryosections were examined at 110 K with a cryoelectron microscope and the state of water was studied on micrographs and electron diffraction patterns. The results are compared with those from liver specimens cryofixed at ambient pressure by plunge freezing. The high-pressure frozen specimens contained crystalline frozen regions as well as areas which were vitreous. The spot diffraction patterns from crystalline regions are found to differ from those known for hexagonal ice. The comparison with powder diffraction data reveals the presence of the high-density morphologies Ice II and Ice III. Vitreous areas of biological samples frozen at ambient pressure are optically denser than areas where the water crystallised as cubic or hexagonal ice. However, on micrographs from high-pressure frozen samples, no significant contrast is found. This observation is explained by the higher specific mass of high-pressure ice compared to Ice I, an interpretation which requires a higher specific mass for high-pressure vitreous water compared to vitreous water produced at ambient pressure. The larger diffuse first ring of the diffraction pattern from high-pressure vitreous water confirms this argument.     

Expression of proliferating cell nuclear antigen(PCNA) in biopsy and autopsy specimens of gastric carcinoma

Although proliferating cell nuclear antigen (PCNA) is known to be an indicator of malignant potential in tumors, the biological and clinicopathological significance of PCNA in tumor tissue is controversial. METHODS: Immunohistochemical expression of PCNA was examined in 58 gastric carcinoma tissues obtained at autopsy to test the clinicopathological significance. In addition, in 24 of the 58 tumor tissues we compared immunohistochemical expression of PCNA in biopsy and autopsy specimens from the same patient in order to know whether the proliferating activity of tumor cells is stationary from the early stage to the end of tumor growth. RESULTS: 1. PCNA was undetectable in some tumor tissues (12.5% in biopsy and 10.3% in autopsy specimens). 2. the frequency of PCNA positive cases and labeling index (LI) (%) of PCNA in tumor tissues were not significantly different between biopsy and autopsy specimens. 3. the intensity of PCNA reaction was not related to prognosis. 4. PCNA positive cases and LI did not correlate with survival condition. CONCLUSION: It is hard to say whether PCNA is a reliable indicator in predicting malignancy and prognosis of gastric cancer.     

Analysis of cut points for screening instruments for alcohol problems in the emergency room

OBJECTIVE: The purpose of this study is to evaluate the performance of a number of alcohol screening instruments (CAGE, Brief MAST, AUDIT, TWEAK), in an emergency room population, against ICD-10 criteria for harmful drinking and for alcohol dependence from the CIDI, by gender, race and injury status. METHOD: A probability sample of patients were interviewed (N = 1,330) at the University of Mississippi Medical Center. Analyses were carried out on only current drinkers (n = 771; 58% of the sample). Instruments were compared on sensitivity, specificity and area under the curve using receiver operating characteristic (ROC) analysis to determine optimum cut points. RESULTS: Overall the TWEAK and AUDIT performed best (in relation to sensitivity and area under the ROC curve) at standard cut points (3 and 8, respectively) for both harmful drinking and alcohol dependence. These instruments did not perform equally well across all subgroups, however, particularly among women, and among whites where the CAGE, with a cut point of 1, outperformed both the TWEAK and AUDIT at standard cut points. The TWEAK at a cut point of 2 also did as well as the CAGE at a cut point of 1 among women. CONCLUSION: These data suggest that standard screening instruments do not perform equally well across ethnic and gender subgroups and that consideration of alternative cut points may be appropriate in some populations.     

Usefulness of precracked charpy specimens for fracture toughness screening tests of titanium alloys

Although theK _IC value of a material is a very useful measure of fracture toughness, its valid experimental determination can be a complex and expensive procedure, not at present suited to routine alloy screening or quality control purposes. To explore the feasibility of estimatingK _IC in titanium alloys using techniques that are more convenient to perform, impact and slow-bend tests were made on either V-notched or fatigue-precracked Charpy specimens, and the resulting energy values were compared with the corresponding approximateK _IC values. Of the various tests studied, results from five titanium-based alloys, two steels, and two aluminum alloys showed that precracked specimens broken in slow-bend hold the most promise of giving energy values that can be related toK _IC . The best correlation came from specimens having mostly flat fractures, but in the higher-toughness cases, where shear lips of an appreciable size were formed, just as reasonable a relationship between energy andK _IC was observed when flat-fracture energies were used.     

Phytochemical and toxicological screening of household ornamental plants potentially toxic to humans. I

Thirty different genera of household ornamental plants have been investigated to determine the loci and natures of potential toxins and any injurious effects produced in experimental animals. Different plant parts were tested for alkaloids, glycosides, steroids, saponins, and cyanogenic glycosides. At least seven genera showed detectable concentrations of alkaloids. Glycoside tests were variable, and there was an indication that several species may contain steroid components. Sixteen genera showed positive saponin foam tests. None of the species were clearly cyanogenic. Preliminary biologic screening on rats and mice is given.     

The psychological autopsy: a useful tool for determining proximate causation in suicide cases

This overview article examines the applications of the psychological autopsy method in determining proximate causation in suicide cases. The article reviews the history of the psychological autopsy and describes its procedure and how it has proved helpful in explicating proximate causation. The five standards currently used by the courts to determine proximate causation in suicide cases are described, as are a variety of applications of the psychological autopsy method, including its application to workers' compensation cases, product liability cases, and medical malpractice cases. In particular, issues of prediction and protection are addressed. Finally, there is a discussion of an application of the psychological autopsy to criminal cases. The article concludes with a discussion of the issues raised in the use of the psychological autopsy during expert testimony and the considerations that should be addressed by an expert witness contemplating the use of the psychological autopsy method.     

The role of clinical autopsy in monitoring the quality of the clinical diagnosis in an emergency department

OBJECTIVE: A total of 61 autopsies performed in patients died in emergency department of a university hospital were retrospectively analysed and the findings were compared with clinical diagnoses. METHODS: Sensitivity and specificity of the clinical diagnoses and the correction of medical procedures were measured. The influence of age and sex of patients was analyzed using Fisher's exact test and chi-square-test. RESULTS: The most common causes of death were cardiovascular diseases (52.46%). Autopsy showed unexpected major findings in 44.26% of cases. Major discrepancies between the autopsy reports and the clinical diagnoses, were present in 26.22% of all cases. Absolute concordance between clinical and autopsy diagnoses was obtained in 44.26% of cases. The major sensitivity of clinical diagnosis was found in cerebrovascular disorders (100%), upper digestive hemorrhage (100%), and acute myocardial infarction (82.35%). The lowest sensitivity was found in malignant tumors (16.66%), hemorrhagic pancreatitis (0%) and bowel infarction (0%). The patient cares were correct in 68.85% of cases. No statistically significant differences were observed in relation to age and sex. CONCLUSIONS: We concluded that autopsy is a useful method for evaluate diagnostic procedures and quality of medical cares in emergency departments.     

High-performance liquid chromatographic assay for diltiazem in small-volume blood specimens and application to pharmacokinetic studies in rats

A high-performance liquid chromatographic (HPLC) method was developed which involves the use of two 5-microns BDS silica gel columns (15 cm x 4.6 mm I.D.) in series for increased resolution and sensitivity, and an organic mobile phase for both extraction and elution of diltiazem. Plasma samples (400 microliters) were extracted using the organic mobile phase [n-hexane-methanol-dichloromethane-ammonia (370:35:30:0.3)] and the extracts were monitored at 240 nm. Desipramine (30 micrograms ml-1) was the internal standard. The limit of quantification in plasma was 20 ng ml-1 with a correlation coefficient of > or = 0.999 within the 20-800 ng ml-1 standard window. The inter- and intra-assay R.S.D.s were within 5%. The recovery of diltiazem varied from 101.1% at 20 ng ml-1 to 93.7% at 400 ng ml-1. The method was applied to the investigation of diltiazem absorption in a rat. Drug absorption was based on the intestinal single-pass perfusion model. The concentration of diltiazem in all test perfusion solutions was 1 mg ml-1 (2.4 mM) and the flow-rate through the system was 3.33.10(-3) ml s-1. A non-specific mucolytic absorption enhancer was also added to a diltiazem solution and studied in the in situ system. The pharmacokinetics of diltiazem hydrochloride were investigated in two study groups of Wistar rats (n = 4). A two-sample Student's t-test was employed to compare values of the area under the curve (AUC). The pharmacokinetic data indicated that the AUC in the group which received the enhancer [18.12 +/- 5.43 ng ml-1 h-1 (+/- S.D.)] was higher than that in the control group (11.49 +/- 3.67 ng h-1 ml-1), t-test; p = 0.0483. Hence it was shown that administration of an enhancer could increase the oral bioavailability of diltiazem.     

Gas-chromatographic identification of drugs in gastric aspirate samples: a rapid screening procedure for emergency toxicology

Gastric aspirate has not been used frequently in the identification of ingested drugs. Because there is only qualitative significance in such a sample, a new method is described that facilitates identification. A 1-ml gastric aspirate sample is extracted with 100 mul of chloroform and analyzed directly by gas chromatography. Seventeen drugs commonly involved in overdose cases are included in this 25-min procedure. The gastric drug screen has been applied to more than 500 patients, and results are described.     

Clinical application of transiently evoked otoacoustic emissions in screening for auditory dysfunction

Transiently evoked otoacoustic emissions (TEOAE) should be used clinically as an objective and noninvasive screening test for auditory dysfunction in children. The features of TEOAE measured by "ILO88" with non linear click stimuli are discussed. The following results were obtained: 1) The normal range of a power spectrum was determined using 42 adults with normal hearing and compared with data for sensorineural hearing disturbance. The power spectrum of TEOAE in adults with normal hearing sloped downward at high frequency and was the same for right and left ears in both males and females. For comparison with sensorineural hearing disturbance, a significant correlation between the audiogram and power spectrum of TEOAE was sought. 2) Patients with otitis media with effusion (109 ears in 67 children) were examined by audiometry, tympanometry and TEOAE. The hearing disturbance threshold of 45 cases with TEOAE was lower than that in cases with no TEOAE. In tympanometry, low intratympanic pressure was noted in the absence of TEOAE. 3) TEOAE and spontaneous otoacoustic emission were examined in 42 adults with normal hearing and 27 neonates using the same probe and level of stimuli to clarify differences in TEOAE according to age. The amplitude of TEOAE and the highest peak of the frequency component at 4kHz in neonates exceeded those of adults. The peak stimuli recorded with the intracanal probe in neonates was also larger than that of adults. Three out of 15 neonates had spontaneous otoacoustic emission and essentially the same proportion was noted in young adults.(ABSTRACT TRUNCATED AT 250 WORDS)     

Coronary atherosclerosis, coronary thrombosis and myocardial infarction in autopsy cases (author's transl)

The autopsy reports of the Pathological Institute Erfurt of the period from 1.1 1951 until 31.12. 1969 were scored for cases of coronary sclerosis which were analysed concerning frequency and distribution of age and sex, resp. In 52.26 percent of all autopsies (55.77 percent of men, 48.06 percent of women) a coronary sclerosis was present. Weak or moderately severe coronary sclerosis appeared more frequent (34.47 percent) than severe forms (17.80 percent of all autopsies). The difference in the relative frequency of coronary sclerosis between our material and the data of other authors we explain by subjective factors in the interpretation of the morphological changes of the coronary vessels. Males suffered significantly more frequent from all forms of coronary sclerosis. During the period of nineteen years a significant increase of the coronary sclerosis was observed. It is due to the more frequent occurrence of weak to moderately severe coronary sclerosis in both sexes, and of severe forms in men. The increase of the frequency of the coronary sclerosis particularly concerns the younger age groups.     

Quantification of Chlamydia trachomatis in cervical and urine specimens from women attending a genitourinary medicine clinic: implications for screening strategies

Population screening and intervention programmes can reduce the prevalence and incidence of infection with Chlamydia trachomatis, especially if sensitive molecular diagnostic tests are used. However, diagnostic tests that perform well on genitourinary medicine (GUM) clinic populations may be less useful for screening, particularly if the majority of infected subjects are asymptomatic and their samples contain fewer organisms. We have compared the extent of low organism load in cervical and urine samples from symptomatic and asymptomatic chlamydia-positive women, by using a direct fluorescent antibody staining method and counting the chlamydial elementary bodies (EBs). We have investigated the ability of an enzyme immunoassay (EIA; MicroTrak) and a DNA amplification (ligase chain reaction; LCR) assay to detect low numbers of organisms in cervical samples and the ability of the LCR assay to detect low numbers of organisms in urine. A low organism load (< 10 EBs) was seen by direct fluorescent antibody (DFA) staining in about 30% of cervical samples and in about 75% of urines from chlamydia-positive women; the proportions in symptomatic women were not significantly different from those in asymptomatic women. The EIA identified only 16% of cervical samples that contained < 10 EBs by DFA staining; the LCR identified 100% of cervical samples and 93% of urine samples that contained < 10 EBs by DFA staining. The findings suggest that the ability of chlamydial diagnostic tests to identify positive women should be similar among patients attending a GUM clinic and those taking part in a population screening programme, and that sensitive molecular assays such as the LCR should identify subjects with a low organism load in both groups.     

Seroepidemiologic study on the feasibility of screening for the antibody to HCV by pooling the serum specimens

The feasibility of screening for the antibody to HCV by pooling 10 serum specimens was studied by utilizing the epidemiologic method of single blind random allocation. We changed only the ratio between the pooled serum specimen volume and the serum specimen diluent volume, with their total volume and single serum specimen volume being as much as the volume required by EIA. Other steps were the same as those of EIA. The result showed that taking single serum specimen as the control group, the sensitivity and specificity of pooled serum specimen were 100% and 97.6%, respectively. The false positive rate was 2.4%, Kappa value was 0.95 (P < 0.05). The analysis of profit found that remarkable social and economic benefit will be obtained when serum pooling method is used. These results demonstrate that pooling 10 serum specimens is feasible to screening the antibody to HCV in blood donors by EIA.     

Differences in performance of screening instruments for problem drinking among blacks, whites and Hispanics in an emergency room population

BACKGROUND: As new methods for corneal curvature measurement have evolved, users of videokeratscopes need to know the practical limitations of these instruments. We assessed agreement between keratometry and videokeratography in measuring highly astigmatic corneas. METHODS: Two independent examiners made three keratometric and videokeratographic measurements on each of 33 corneas after penetrating keratoplasty. The non-orthogonal keratometric readings obtained with a Zeiss 10 SL/O keratometer (Carl Zeiss Ltd.) were compared to the non-orthogonal simK readings (maxK, minK) calculated by the algorithms of a TMS-1 videokeratoscope (Tomey). Measurement agreement was evaluated for steep and flat meridian power and location, and astigmatism magnitude (D). RESULTS: A systematic bias of the TMS-1 in measuring steeper than keratometry for the steep meridian was demonstrated (95% confidence interval: -0.34 to -1.20 D). The limits of agreement (d - 2SD to d + 2SD) between the two instruments were found to be unacceptable for clinical purposes in measuring steep meridian power (-3.17 to +1.63 D), flat meridian power (-4.92 to +4.48 D) and astigmatism magnitude (-5.84 to +4.87 D). Clinically acceptable differences were observed in identification of steep and flat meridian location. CONCLUSIONS: The Zeiss 10 SL/O keratometer and the TMS-1 videokeratoscope showed poor measurement agreement for irregular corneal surfaces, despite the good correlation previously shown between keratometry and videokeratography in calibrated spheres and regular corneas. The TMS-1 showed a systematic bias, measuring a greater power in the steeper meridian than the Zeiss 10 SL/O keratometer. It is suggested that the two instruments cannot be used interchangeably in comparing the curvature of corneas after penetrating keratoplasty.     

Metals in lung tissue from autopsy cases in Mexico City residents: comparison of cases from the 1950s and the 1980s

In autopsies performed on residents of Mexico City during the 1950s and 1980s (45 males and 24 females and 42 males and 42 females, respectively), concentrations of cadmium, copper, cobalt, nickel, and lead in the lungs were studied by atomic absorption spectrometry. Sharp increases were noted in samples taken in the 1980s compared to those from the 1950s. In samples from both time periods, the concentrations were influenced by gender. Smoking was not associated with higher levels of the metals. Only lead seemed to have a relation with age. The enormous differences by gender in the 1950s could be due to different patterns of exposure. The differences among samples from both periods appear to be associated with the increase of air pollutants in the metropolitan areas of Mexico City during the years under study. These results reinforce the importance of studying lung tissue to monitor air pollution by metals.