Improved image quality for epifluorescence microscopes through adapting confocal techniques.
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Animals↗
Biomedical subjects
S Schwartz
Publications and source records attributed to S Schwartz.
[The effect of sepsis on liver protein synthesis].
A study was made of the possible influence of sepsis on liver protein synthesis in septic and control rats, fed either parenterally (TPN) or with water and feed available "ad libitum". Liver protein synthesis was determined using the single massive dose method. In experiment I, the septic and control animals received TPN for twenty-four hours: in experiment II water and food was available to them "ad libitum". Twenty-four hours after the sepsis occurred, the animals were injected with a massive dose of 14C-labelled leucine, and slaughtered by decapitation. The septic animals with water and feed available "ad libitum" were fasted voluntarily without any intake. This group of fasted septic animals was the only one which lost weight. Liver protein synthesis increased in septic animals in comparison with the control animals, whether receiving TPN (112.2 +/- 8/78.5 +/- 13) or with "ad libitum" nutrition (97.2 +/- 15/60.8 +/- 8). The increased liver protein synthesis in the septic animals was modified (although with reduced significance) by parenteral nutrition (112.2 +/- 8/97.2 +/- 15). Our results suggest that sepsis increases liver protein synthesis, and that this protein synthesis may be enhanced by parenteral nutrition.
Animals↗
Inhibition of visceral protein synthesis by certain amino acid supplements.
This study was focused on the effects produced by diets with different amino acid proportions on visceral protein synthesis (liver and jejunal mucosa). Eight groups of rats received an enteral modular diet supplemented with different amino acids (Group 1: Ile, Leu, Val; Group 2: Phe, Met, Gly; Group 3: Glu, Arg, Gly; Group 4: Gly, Group 5: Orn-Asp, Cys, Pro; Group 6: Lys, Ser, Thr; Group 7: Tyr, His, Ala). Group 8 was the control group. Rats were fed for four days. At the end of this period a flooding dose of 14C-Leu was injected and animals were killed. Liver and jejunal mucosa were removed and protein synthesis rate was determined. Results show a decreased liver protein synthesis in group fed with aromatic amino acids (53.8 +/- 8.4 vs. 88.6 +/- 12.1) and Glu-Arg (68.6 +/- 10.9). In jejunal mucosa there was a decrease of protein synthesis in groups fed with aromatic amino acids (98.7 +/- 16 vs 160.5 +/- 49). These changes seem to be related to the intracellular amino acid pool size and its influence on protein metabolism.
Amino Acids↗
Comparing different types of performance feedback and computer-based instruction in teaching medical students how to diagnose acute abdominal pain.
PURPOSE: To examine the relative efficacies of three types of performance feedback used with computer-based instruction (CBI) in making diagnoses. METHOD: In 1990, 75 final-year medical students at The University of Queensland were pretested for domain knowledge and diagnostic skill in the area of acute abdominal pain. The students were also asked to indicate their confidence in each of their diagnoses. Following these pretests, the students were randomly divided into five groups of 15 students each. One group received traditional CBI, using a "question-and-explanation" format, to learn domain knowledge. The other four groups received one of two types of CBI to learn diagnostic accuracy, and these four groups received one of three types of performance feedback (which differed considerably in the amounts of information imparted). Then the students took posttests. One-way analysis of variance, Student's t-test, and the Tukey test were used to compare the performances of the different groups of students. RESULTS: Although the students in the traditional CBI group significantly improved their performance on multiple-choice questions (by 58%) compared with the other groups of students (6-10% improvement), these students did not improve their diagnostic performance. In contrast, the CBI groups that used simulated-patient cases and structured-performance feedback did improve their diagnostic accuracy (by as much as 16%, compared with a 1% decline for the traditional CBI group). Contrary to expectation, the different types of feedback were equally effective. Except for the students in the traditional CBI group, the students' confidence increased from pretest to posttest regardless of their performances. CONCLUSION: CBI that uses simulated-patient cases and structured-performance feedback seems to be efficient and effective compared with traditional CBI methods. However, care should be taken to ensure that students do not become overconfident of their abilities.
Abdominal Pain↗
Proficiency testing in clinical cytogenetics. A 6-year experience with photographs, fixed cells, and fresh blood.
The College of American Pathologists and the American Society of Human Genetics offer a proficiency testing program in clinical cytogenetics. Two hundred twenty-five laboratories now provide data for this survey, which was begun in 1986. Challenges have consisted of photographed metaphases, fixed lymphoblastoid cell suspensions, fresh peripheral blood, and disarranged karyotypes. The "correct" response was based on 80% or greater consensus among either the referees or the participants. Referee laboratories performed better than participants. More laboratories were able to report accurate recognition of abnormalities by using a coded list than could write the interpretation in standardized nomenclature. Deletions, unbalanced translocations, and inversions were more difficult challenges than balanced translocations or trisomies. Prenatal and lymphocyte challenges were more likely to result in consensus than were bone marrow challenges. Participants performed best on whole-blood challenges. Fixed cell suspensions were less satisfactory. Excellent quality case material is essential for a successful challenge. A grading system has been devised to separate artifacts of the survey process from proficiency variables.
Chromosome Aberrations↗
Gastrointestinal blood loss in older infants: impact of cow milk versus formula.
Concerns that consumption of whole cow milk (WCM) by older infants may result in excessive gastrointestinal blood loss and subsequent iron deficiency led us to perform a prospective, randomized study in 104 infants. Infants were assigned to receive WCM beginning at 6 months or one of three formulas beginning at 4-6 months of age and followed until 12 months of age. Gastrointestinal blood loss was similar for all groups, as determined by both qualitative (Hemoccult II) and quantitative testing (HemoQuant). There was no association between concentration of fecal hemoglobin and volume of WCM consumed or iron status by 12 months of age. Of eight infants (seven WCM, one formula) who became iron-depleted, none had excessive fecal hemoglobin excretion. When pooled and analyzed regardless of feeding group, fecal hemoglobin increased with age and was greater at 11 and 12 months than at younger ages. We conclude that although infants fed WCM are at increased risk of developing iron depletion, the iron insufficiency is not due to gastrointestinal blood loss. We further conclude, based on our sample of normal infants age 4-12 months, that fecal hemoglobin concentrations of 0.5-0.8 mg/g stool correspond to the upper limits of normal, values much lower than in adults.
Analysis of Variance↗
Efficacy and applicability of interphase fluorescence in situ hybridization for prenatal diagnosis.
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Female↗
Characterization of de novo duplications in eight patients by using fluorescence in situ hybridization with chromosome-specific DNA libraries.
Fluorescence in situ hybridization (FISH) with chromosome-specific DNA libraries was performed on samples from eight patients with de novo chromosomal duplications. In five cases, the clinical phenotype and/or cytogenetic evaluations suggested a likely origin of the duplicated material. In the remaining three cases, careful examination of the GTG-banding pattern indicated multiple possible origins; hybridization with more than one chromosome-specific library was performed on two of these cases. In all cases, FISH conclusively identified the chromosomal origin of the duplicated material. In addition, the hybridization pattern was useful in quantitatively delineating the duplication in two cases.
Aneuploidy↗
Socioeconomic status and psychiatric disorders: the causation-selection issue.
Are inverse relations between psychiatric disorders and socioeconomic status due more to social causation (adversity and stress) or social selection (downward mobility of genetically predisposed)? This classical epidemiological issue is tested by focusing on ethnic status in relation to socioeconomic status. Ethnic status cannot be an effect of disorder because it is present at birth whereas socioeconomic status depends on educational and occupational attainment. A birth cohort sample of 4914 young, Israel-born adults of European and North African background was selected from the country's population register, screened, and diagnosed by psychiatrists. Results indicate that social selection may be more important for schizophrenia and that social causation may be more important for depression in women and for antisocial personality and substance use disorders in men.
Education↗
Prenatal detection of 45,X/46,XX/47,XXX mosaicism through amniocentesis: mosaicism confirmed in cord blood, amnion, and chorion.
Sex chromosome mosaicism in amniotic fluid cells poses a serious dilemma in prenatal diagnosis. Chromosome analysis of 56 primary clones of amniocytes revealed three distinct cell lines. Nine cells (16.1 per cent) demonstrated a 45,X karyotype, 11 cells (19.6 per cent) a 47,XXX karyotype, and the remaining 36 cells (64.3 per cent) had a modal number of 46 chromosomes (46,XX). Cytogenetic evaluation of 100 cells from cord blood, amnion, and chorion following delivery confirmed this triple mosaicism. However, the distribution of the three karyotypes in the pre- and postnatal samples was not found in the same proportions. The cord blood had the most similar frequency to that of the amniotic fluid sample, while the chorion had a significantly increased frequency of 47,XXX cells (41 per cent) and a decreased frequency of 45,X cells (2 per cent). Physical examination of the infant at birth revealed no discernible phenotypic abnormalities. Parental karyotypes were normal. This case highlights the difficulty in determining whether a prenatally detected abnormality will be associated with postnatal phenotypic deviation.
Adult↗
An unusual mosaic karyotype detected through prenatal diagnosis with duplication of 1q and 19p and associated teratoma development.
A 40-year-old white woman underwent amniocentesis for advanced maternal age at 15.4 weeks gestation. Fetal chromosome analysis demonstrated two distinct cell lines: [46,XX,t(1;19)(p11;p11)]--10%; and [47,XX,t(1;19)(p11;p11) + der(1)t(1;19)(p11;q11)]--90%. The latter karyotype was trisomic for both 1q and 19p. The mother carried the balanced translocation; the father had a normal karyotype. Amniotic fluid alpha-fetoprotein level was elevated and an acetylcholinesterase band was detected. Level II ultrasonography at 17 and 24 weeks revealed several abnormalities, including a large facial cleft and a probable facial teratoma and intracranial tumor. Autopsy following pregnancy termination confirmed the presence of both. Chromosome evaluation of 172 metaphases of both the epignathus and the intracranial teratoma demonstrated a predominance of the cell line with 47 chromosomes (166/172 = 96.5%), while from nonteratoma tissue (lung, liver, skin, and brain) only the balanced karyotype was detected. These observations suggest that the chromosomal imbalance is instrumental in the etiology of the teratoma.
Abnormalities, Multiple↗
Validation of a new quality of life questionnaire for benign prostatic hyperplasia.
In planning a longitudinal study to characterize the natural history of benign prostatic hyperplasia (BPH), we validated a new disease-specific quality of life questionnaire in a pilot study. We studied 110 men in Rochester, Minnesota who spanned the severity of BPH, from men with no known BPH to men who underwent surgery for this condition. Baseline data were obtained on all men, and the 30 who underwent prostatectomy were re-interviewed to test responsiveness. Reproducibility was examined on the pre-post responses (10 weeks apart) of the 37 men with BPH who did not undergo prostatectomy. Six of twelve question domains were retained in the final questionnaire on the basis of their responsiveness to change, reproducibility, internal consistency, and validity. These were: urinary symptoms, degree of bother due to urinary symptoms, BPH-specific interference with activities, general psychological well-being, worries and concerns, and sexual satisfaction. Most of the more generic measures were deleted.
Adult↗
Multiple-marker screening in pregnancies with hydropic and nonhydropic Turner syndrome.
OBJECTIVE: The combination of maternal serum alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin levels and maternal age has been used to increase the sensitivity of screening for fetal Down syndrome and trisomy 18 in early-second-trimester pregnancies. We hypothesized that a unique pattern of these analytes also may be characteristic of fetal Turner syndrome, with or without hydrops. STUDY DESIGN: We studied preamniocentesis, second-trimester maternal serum specimens from seven hydropic and eight nonhydropic cases of fetal Turner syndrome. Clinical and pathologic records were reviewed. Statistical analysis of the data was performed by the rank sum test. RESULTS: In both hydropic and nonhydropic cases, alpha-fetoprotein levels were slightly reduced, and unconjugated estriol levels were markedly reduced. In hydropic pregnancies human chorionic gonadotropin levels were elevated, and nonhydropic pregnancies had low human chorionic gonadotropin levels (p = 0.001). CONCLUSIONS: The results suggest that the morphologic defect of hydrops, rather than the aneuploidy itself, is responsible for the elevation in human chorionic gonadotropin. In conjunction with the low unconjugated estriol levels, the elevation in human chorionic gonadotropin levels will result in the prenatal identification of hydropic fetal Turner syndrome pregnancies as being at increased risk for fetal Down syndrome.
Biomarkers↗
Parallelization of a local similarity algorithm.
The local similarity problem is to determine the similar regions within two given sequences. We recently developed a dynamic programming algorithm for the local similarity problem that requires only space proportional to the sum of the two sequence lengths, whereas earlier methods use space proportional to the product of the lengths. In this paper, we describe how to parallelize the new algorithm and present results of experimental studies on an Intel hypercube. The parallel method provides rapid, high-resolution alignments for users of our software toolkit for pairwise sequence comparison, as illustrated here by a comparison of the chloroplast genomes of tobacco and liverwort.
Algorithms↗
The control group conundrum in chronic pain case/control studies.
The choice of an appropriate control group has been recognized as one of the most difficult problems in the methodology of case/control studies, both in theory and in practice. In the study of chronic pain, a "well control group" has frequently been employed. Although this design has intuitive appeal, it contains the potential for bias and error. In order to obtain the proper control group, the same exclusion criteria should be applied to cases and controls. Second, controls should be selected independently of exposure to the putative risk factors under investigation. To illustrate the nature of this problem we present two numerical examples, using a chronic pain disorder.
Case-Control Studies↗
Distinct RNA sequences in the gag region of human immunodeficiency virus type 1 decrease RNA stability and inhibit expression in the absence of Rev protein.
The expression of Gag, Pol, Vif, Vpr, Vpu, and Env proteins from unspliced and partially spliced human immunodeficiency virus type 1 (HIV-1) mRNAs depends on the viral protein Rev, while the production of Tat, Rev, and Nef from multiply spliced mRNAs does not require Rev. To investigate the difference between gag and tat mRNAs, we generated plasmids expressing tat-gag hybrid mRNAs. Insertion of the gag gene downstream of the tat open reading frame in the tat cDNA resulted in the inhibition of Tat production. This inhibition was caused, at least in part, by a decrease in the stability of the produced mRNA. Deletions in gag defined a 218-nucleotide inhibitory sequence named INS-1 and located at the 5' end of the gag gene. Further experiments indicated the presence of more than one inhibitory sequence in the gag-protease gene region of the viral genome. The inhibitory effect of INS-1 was counteracted by the positive effect mediated by the Rev-Rev-responsive element interaction, indicating that this sequence is important for Rev-regulated gag expression. The INS-1 sequence did not contain any known HIV-1 splice sites and acted independently of splicing. It was found to have an unusually high AU content (61.5% AU), a common feature among cellular mRNAs with short half-lives. These results suggest that HIV-1 and possibly other lentiviruses have evolved to express unstable mRNAs which require additional regulatory factors for their expression. This strategy may offer the virus several advantages, including the ability to enter a state of low or latent expression in the host.
Blotting, Northern↗
Mutational inactivation of an inhibitory sequence in human immunodeficiency virus type 1 results in Rev-independent gag expression.
We have characterized an inhibitory RNA element in the human immunodeficiency virus type 1 (HIV-1) gag coding sequence that prevents gag expression. The inhibition exerted by this element could be overcome by the presence of the Rev-responsive element in cis and of Rev protein in trans. To understand the mechanism of function, we inactivated the inhibitory element by mutagenesis while maintaining an intact gag coding region. A constitutive high level of Rev-independent gag expression was achieved only after the introduction of 28 point mutations over a large region of 270 nucleotides within the gag coding region. To our knowledge, this is the first demonstration of inactivation of a negative RNA element within a coding region without alteration of the expressed protein. Elimination of the inhibitory element in the p17gag region, named INS-1, offered the opportunity to detect a second inhibitory element in the gag-pol region. The presence of either INS element is sufficient to inhibit gag expression, demonstrating that multiple INS elements acting independently can inhibit HIV RNA expression. Expression of gag from Rous sarcoma virus, a retrovirus that does not require Rev-like regulatory proteins, revealed that the Rous sarcoma virus p19gag region does not contain inhibitory elements. These results demonstrate the presence of a strong inhibitory element acting at the level of mRNA and provide a general method for the removal of such elements from mRNA coding regions. The inhibitory element functions in the absence of any HIV-1 proteins, suggesting that cellular factors are responsible for this inhibition.
Base Sequence↗
Mechanism of translation of monocistronic and multicistronic human immunodeficiency virus type 1 mRNAs.
We have used a panel of cDNA clones expressing wild-type and mutant human immunodeficiency virus type 1 (HIV-1) mRNAs to study translation of these mRNAs in eucaryotic cells. The tat open reading frame (ORF) has a strong signal for translation initiation, while rev and vpu ORFs have weaker signals. The expression of downstream ORFs is inhibited in mRNAs that contain the tat ORF as the first ORF. In contrast, downstream ORFs are expressed efficiently from mRNAs that have rev or vpu as the first ORF. All env mRNAs contain the upstream vpu ORF. Expression of HIV-1 Env protein requires a weak vpu AUG, which allows leaky scanning to occur, thereby allowing ribosomes access to the downstream env ORF. We concluded that HIV-1 mRNAs are translated by the scanning mechanism and that expression of more than one protein from each mRNA was caused by leaky scanning at the first AUG of the mRNA.
Base Sequence↗