Using POSTDOC to recognize biomedical concepts in medical school curricular documents

Recognition of the biomedical concepts in a document is prerequisite to further processing of the document: medical educators examine curricular documents to discover the coverage of certain topics, detect unwanted redundancies, integrate new content, and delete old content; and clinicians are concerned with terms in patient medical records for purposes ranging from creation of an electronic medical record to identification of medical literature relevant to a particular case. POSTDOC (POSTprocessor of DOCuments) is a computer application that (1) accepts as input a free-text, ASCII-formatted document and uses the Unified Medical Language System (UMLS) Metathesaurus to recognize relevant main concept terms; (2) provides term co-occurrence data and thus is able to identify potentially increasing correlations among concepts within the document; and (3) retrieves references from MEDLINE files based on user identification of relevant subjects. This paper describes a formative evaluation of POSTDOC's ability to recognize UMLS Metathesaurus biomedical concepts in medical school lecture outlines. The "precision" and "recall" varied over a wide range and were deemed not yet acceptable for automated creation of a database of concepts from curricular documents. However, results were good enough to warrant further study and continued system development.

Endobronchial radiation therapy with or without neodymium yttrium aluminum garnet laser resection for managing malignant airway obstruction

BACKGROUND

Previous reports have shown low-dose-rate (LDR) afterloading Ir-192 endobronchial radiation therapy (EnBRT) to effectively palliate symptoms in patients with malignant airway obstruction. The authors retrospectively assessed the consequences of LDR EnBRT with or without neodymium yttrium aluminum garnet (Nd:YAG) laser resection in 37 patients.

METHODS

Between February 1986 and June 1991, 37 patients with malignant airway obstruction were treated with LDR EnBRT at The Cleveland Clinic Foundation. Inclusion criteria for LDR EnBRT with or without Nd:YAG laser resection were patients with recurrent, symptomatic endobronchial lesions treated previously with external beam irradiation. Of the 37 patients, 21 patients with endobronchial lesions underwent Nd:YAG laser resection; 16 patients with mainly extrinsic lesions received EnBRT only. Before EnBRT, selected patients (7 of 16 in the nonlaser-treatment group and 14 of 21 in the laser-treatment group) received additional external beam treatments of 2000 cGy/10 fractions. The LDR afterloading Ir-192 technique was used to deliver approximately 30 Gy to a 1.0-cm radius target.

RESULTS

All patients had one or more of the following symptoms: 1) dyspnea, 2) fever, 3) cough, and 4) hemoptysis. Good-to-excellent symptom relief was apparent in 16 of 21 (76.2%) laser-treated patients and in 12 of 16 (75%) nonlaser-treated patients. Follow-up bronchoscopy in 28 patients revealed tumor regression in 22 (79%). Median survival time was 16.3 weeks in the laser group and 11.7 weeks in the nonlaser group (P = 0.36). Longer median survival times were noted in laser-treated (22.8 weeks) and nonlaser-treated (16.4 weeks) patients receiving additional external beam treatments. Exsanguination occurred in 7 of 21 (33.3%) laser-treated patients and in 4 of 16 (25%) nonlaser-treated patients. The only factor affecting the exsanguination rate was implant location: 6 of 11 (54.5%) patients had lesions in the right or left upper lobe.

CONCLUSIONS

EnBRT alone or with Nd:YAG laser resection provided good-to-excellent symptom palliation in these patients although a high rate of exsanguination occurred in both groups.

Patent foramen ovale and brain infarct. Echocardiographic predictors, recurrence, and prevention

BACKGROUND AND PURPOSE

Paradoxical embolism through a patent foramen ovale is a recognized cause of stroke, but clinical predictors, recurrence rate, and prevention of brain infarcts in patients with patent foramen ovale have not been determined. We reviewed transesophageal echocardiographic records to ascertain echocardiographic predictors and optimal prophylaxis for patent foramen ovale-related infarcts.

METHODS

A patent foramen ovale was identified in 74 patients during 615 transesophageal echocardiograms by color Doppler or saline contrast during a 60-month period. On the basis of final clinical situation, the patients were divided into the following groups: group 1, infarct with patent foramen ovale a likely cause (n = 16); group 2, infarct with patent foramen ovale an unlikely cause (n = 23); and group 3, no infarct (n = 35). Transesophageal echocardiograms were reviewed to assess patent foramen ovale characteristics and associated cardio-embolic sources without knowledge of clinical details or group assignment. Follow-up after a patent foramen ovale-related infarct was obtained by telephone or written correspondence in 15 of 16 group 1 patients.

RESULTS

Atrial septal aneurysms were more common in group 1 (38%) compared with group 2 (10%) and group 3 (8%) (P = .02). Contrast right-to-left shunting occurred in 88% of group 1 (P = .06) and 86% of group 2 (P = .07) compared with 60% of group 3. Prevention of recurrence in subjects with presumed patent foramen ovale-related brain infarcts varied. Aspirin was usually chosen after initial brain ischemia. Warfarin and patent foramen ovale closure were usually reserved for subjects with symptoms of brain ischemia while taking aspirin or those who required warfarin or cardiac surgery for other indications. No recurrent infarcts occurred in 15 patients during a mean follow-up period of 28 months.

CONCLUSIONS

Atrial septal aneurysm and right-to-left shunt may be predictive of a patent foramen ovale that predisposes a patient to stroke. Aspirin may provide sufficient infarct prophylaxis after initial ischemia. Warfarin and surgical correction should likely be reserved for those in whom aspirin is not effective or those who require warfarin or cardiac surgery for other reasons until prospective studies are available.

[Application of ORM1 phenotyping in forensic science]

ORM1 is an important genetic marker for both parentage testing and personal identification in forensic science. We have examined the ORM1 phenotypes in the human serum and dried bloodstains using the ULPAGIF method. ORM1 phenotypes were successfully demonstrated from dried bloodstains stored at 4 degrees C and room temperature for up to twenty-four weeks. In bloodstains stored at 37 degrees C, the 100% of ORM1 phenotyping was no longer possible after 12 weeks. We examined 9 bloodstains stored at room temperature for one, two and three years, respectively. For the one-year-old bloodstains, all of the samples could be phenotyped correctly, for the two-year-old bloodstains 8 out of the 9 and for the three-year-old bloodstains 7 out of the 9 samples could be phenotyped correctly. The results have indicated that ORM1 is relatively stable, for it is tolerable toward high temperature and long duration. It was suggested that the bloodstains should be ultrasonicated before ULPAGIF, because the ultrasonication could elevate the detectable rate of ORM1 phenotypes from bloodstains. ORM1 phenotypes was performed in five disputed parentage cases. One of the alleged fathers was excluded.

Cloning and characterization of the RNA polymerase alpha-subunit operon of Chlamydia trachomatis

We have cloned the chlamydial operon that encodes the initiation factor IF1, the ribosomal proteins L36, S13, and S11, and the alpha subunit of RNA polymerase. The genes for S11 and alpha are closely linked in Escherichia coli, Bacillus subtilis, and plant chloroplast genomes, and this arrangement is conserved in Chlamydia spp. The S11 ribosomal protein gene potentially encodes a protein of 125 amino acids with 41 to 42% identity over its entire length to its E. coli and B. subtilis homologs; the gene encoding the alpha subunit specifies a protein of 322 amino acids with 25 to 30% identity over its entire length to its E. coli and B. subtilis homologs. In a T7-based expression system in E. coli, the chlamydial alpha gene directed the synthesis of a 36-kDa protein. Mapping of the chlamydial mRNA transcript by RNase protection studies and by a combination of reverse transcription and the polymerase chain reaction demonstrates that IF1, L36, S13, S11, and alpha are transcribed as a polycistronic transcript.

[Research on hemostatic mechanism of extracts from carbonized Schizonepeta tenuifolia Brig]

It has been shown that StE can significantly shorten PT, TT, KPTT and RT of experimental animals and has an antiheparin function in the body. Meanwhile, it can significantly shorten ELT and strengthen FA. Its hemostatic action is accomplished through promoting coagulation and inhibiting fibrinolysis. 3P test and EG test were negative, it is thus impossible for a large dosage of StE to lead to DIC.

Extra G positive band on the long arm of chromosome 9

Various heteromorphisms of the 9q heterochromatic area have been reported. In most instances, the extra G positive band is accompanied by an extra C band. We describe a family where the extra G band is totally euchromatic and does not include an extra C band. It is not clear whether these two types of variant chromosome 9 arose from a similar mechanism.

Effect of catheter composition on sperm quality

Bladder catheterization for collection of retrograde ejaculates is commonly practiced, although previous studies have shown that materials used in the manufacture of the catheters may be toxic to sperm. Potential toxicity is particularly relevant to electroejaculation, as sperm from anejaculatory individuals undergoing this procedure characteristically exhibit poor motility and viability. To determine the effect of short-term exposure to various catheter materials on sperm quality, donor semen was diluted with BWW medium and aliquots incubated for 1 and 5 minutes with segments of four different catheters. The catheters were composed of latex, silicone rubber, polytetrafluoroethylene (Teflon), and radio-opaque Teflon, respectively. Following incubation, eosin-nigrosin staining for viability was performed and sperm motility assessed using computer-assisted sperm analysis (Cellsoft, Cryo Resources, Ltd). In the second phase of the study, donor semen was incubated with catheter segments coated with 0.3 ml of a water-soluble, nontoxic lubricant (Cellulosagel, Lederle) to evaluate whether the combination adversely affects sperm. Percent motility and viability for the semen specimens incubated with the four catheters alone did not differ significantly from control values either at 1 or at 5 minutes (P = 0.3, motility; P = 0.6, viability). The addition of lubricant did not change the catheter data significantly, indicating the absence of independent or synergistic toxicity (P = 0.5, motility; P = 0.4, viability). This study provides substantial evidence that brief exposure to conventional catheters, with or without a nontoxic lubricant, does not adversely affect sperm motility or viability.(ABSTRACT TRUNCATED AT 250 WORDS)

Variation of perfluoropropane disappearance after vitrectomy

In complex cases of retinal detachment, perfluoropropane (C3F8) is frequently used after vitrectomy for tamponade of retinal breaks. Results of previous studies of C3F8 disappearance using 10% C3F8 after vitrectomy in human eyes have differed significantly. A wide variation in the decay rate and half life of C3F8 after vitrectomy was observed in eyes that had similar clinical settings and received the same C3F8 concentration (15%, 20%, or 25%). This occurred even in those eyes where there was no change in the geometric contour of the eye after a repeat vitrectomy.

[The relationship between hepatitis B and renin-angiotensin-aldosterone system]

The angiotensin II (AT II) levels in plasma were measured 68 times by using radio-immunoassay in 30 patients with viral hepatitis B (HB) and in 35 healthy persons as the control group. The results showed that the AT II levels of patients with HB were much higher than those of the control group (P less than 0.001). They were 219.25 +/- 91.31 ng/L and 60.70 +/- 10.73 ng/L, respectively. These indicated that the renin-angiotensin-aldosterone system (RAAS) of the patients was in exciting state. The levels of 8 cases of severe chronic active hepatitis (SCAH) (AT II = 270.40 +/- 106.55 ng/L, 6 cases of subacute fulminant hepatitis (SFH) (AT II = 332.80 +/- 140.12 ng/L), and 4 cases of hepatocirrhosis (HC) (AT II = 218.50 +/- 97.64 pg/ml) were all higher than those of 8 cases of chronic active hepatitis (CAH) (100.50 +/- 83.81 ng/L) and those of 4 cases of acute icteric hepatitis (A1H) (123.33 +/- 64.97 ng/L). These findings showed that the levels of AT II were directly related with the severity of the illness. The AT II levels of 8 cases of HRS (270.50 +/- 66.31 ng/L) were higher that those without HRS (174.50 +/- 78.48 ng/L). After treatment with captopril (CPT), the renal function of the patients returned to normal and the patients got better, while the AT II levels decreased greatly. The results suggested that high AT II levels in plasma may be one of the causes aggressing the HRS. The CPT may inhibit the produce of AT II and there are some therapeutic effects for the HRS.

Cell-mediated immunity in patients on hemodialysis: relationship with hepatitis B carrier status

We compared cell-mediated immune responses in two groups of patients on hemodialysis. One group of patients were chronic carriers of hepatitis B virus (HBV), and the patients of the other group were HBV antigen negative. Our results show that despite the presence of normal numbers of T cells and an increased CD4/CD8 ratio in both groups of patients compared to healthy controls (p less than 0.0001), only the group of patients who were chronic HBV carriers showed depressed lymphoproliferative responses to phytohemagglutinin (p less than 0.001) and concanavalin A (p less than 0.0001). In contrast, a control group of healthy adult HBV carriers showed normal T cell subsets and lymphoproliferative responses to mitogens, indicating that HBV infection per se did not result in depressed lymphoproliferative responses. These results further substantiate the notion that depressed cell-mediated immunity in chronic renal failure is an important factor in predisposing patients to HBV infection with subsequent development of the chronic carrier state.

Effects of low-dose marine oils on intimal hyperplasia in autologous vein grafts

The effects of low-dose cod-liver oil on intimal hyperplasia of vein grafts were examined in 45 adult mongrel dogs undergoing peripheral arterial reconstruction. Fifteen animals served as the control group, 15 animals were fed a fish-oil supplement containing 240 mg of eicosapentaenoic acid daily, and a further 15 animals received 480 mg of eicosapentaenoic acid daily. Segments of undistended external jugular vein were anastomosed to bilaterally divided femoral arteries. The grafts were harvested at 6 weeks and intimal thickness was measured with a computerized interactive image analyzing system. Serum cholesterol level, prothrombin time, partial thromboplastin time, bleeding time, and platelet counts were measured before the operation and at 2, 4, and 6 weeks after the operation. Plasma levels of thromboxane B2 and prostaglandin F1 alpha and serum levels of eicosapentaenoic acid were measured before and 4 weeks after the operation. Serum cholesterol level increased similarly and significantly in all animals. Serum levels of eicosapentaenoic acid rose proportionately with the oral ingestion of fish oil but did not affect coagulation parameters. Plasma thromboxane B2 and prostaglandin F1 alpha were not significantly affected by the ingestion of marine oils. Intimal thickness was 39 +/- 5 microns in the control dogs. Ingestion of 240 mg of eicosapentaenoic acid reduced intimal thickness to 24 +/- 3 microns at 6 weeks (p less than 0.01). Increasing the dose by a factor of 2 did not decrease intimal thickness further, the intima being 23 +/- 2 microns (p less than 0.005). Our data indicate that small doses of fish oil will reduce intimal proliferation in autologous vein grafts and that marine oils may exert their beneficial effects on intimal hyperplasia by a mechanism other than their known effects on prostanoid metabolism.

Use of enzyme-developed immunoblots scanned by densitometry to compare lot-to-lot variability of Russian-thistle extracts

Two different lots of Russian-thistle extracts from five commercial sources were evaluated by isoelectric focusing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblots of Immobilon transfers from these separations. The immunoblots were developed by an enzyme-linked method and scanned with a densitometer. The two lots of a standardized extracts produced scans that suggested uniformity in allergenic components. Several of the nonstandarized extract lots also appeared quite comparable. With further refinement, immunoblotting with densitometric analysis appears to offer an attractive way to standardize allergen extracts.

Onchocerca volvulus recombinant antigen: physical characterization and clinical correlates with serum reactivity

An Onchocerca volvulus cDNA clone expressing epitopes found in adult and larval parasites, designated lambda RAL-2, was derived from a 1,000-base message present in adult O. volvulus, which encodes a protein with an apparent molecular weight of 17,000. This protein does not appear to be extensively posttranslationally modified. Serum samples from 52 individuals exposed to O. volvulus were examined for antibodies recognizing the lambda RAL-2 recombinant antigen; 77% produced such antibodies. In addition, individuals producing antibodies recognizing the recombinant antigen were significantly less likely to develop some aspects of ocular pathology associated with O. volvulus infection than were individuals who did not do so. These results suggest that recombinant antigens such as that produced by lambda RAL-2 may be useful in attempts to understand the mechanism of O. volvulus-induced ocular pathology.

[Study on application of Tf subtyping in forensic medicine]

Tf is an important genetic marker for both parentage testing and personal identification in forensic medicine. It is valuable in anthropology, genetics and clinical medicine. We examined the Tf subtypes in the human serum and dried bloodstain using the ULPAGIF method. Tf subtyping was performed in four disputed parentage cases. One of the alleged fathers was excluded. Tf subtypes were successfully demonstrated from dried bloodstains kept at 4 degrees C for up to four weeks. In bloodstains kept at room temperature and 37 degrees C, the 100% of Tf subtyping was no longer possible after two weeks (or one day). It was suggested that the bloodstains should be examined no longer than seven weeks if the bloodstains were kept at room temperature; or otherwise they should be stored below 4 degrees C as soon as they are collected in forensic practice.

Diffraction minimization in SAW devices using wide aperture compensation

A relationship is outlined between the previously derived uniform asymptotic expansion (UAE) for surface acoustic waves on anisotropic substrates and the intuitive geometrical theory of diffraction (GTD). It is demonstrated that even for an anisotropic medium, the leading terms in the UAE have a direct interpretation in terms of the simple GTD. This model allows a physical explanation of the mechanism of ;wide aperture diffraction minimization', a simple technique that allows an almost complete elimination of diffractive effects in SAW devices by merely increasing the aperture of the unapodized transducer by a calculable amount. These techniques are illustrated with both theoretical and experimental results.