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S Shahangian

Publications and source records attributed to S Shahangian.

At least 19 recordsLinked to original sources
PubMed1992

Concentration dependencies of immunoturbidimetric dose-response curves: immunoturbidimetric titer and reactivity, and relevance to design of turbidimetric immunoassays.

To characterize polyclonal antisera for two-point immunoturbidimetric applications, we defined, as functions of antiserum concentration, two parameters derived from dose-response curves: the maximum bichromatic optical response, Tmax, and the antigen concentration in the region of excess antibody corresponding to one-half Tmax, or C50. We raised monospecific polyclonal antisera in goats against several human immunoglobulins, C-reactive protein, C3, C4, apolipoproteins A-I and B, and several other proteins. We could linearly relate the logarithm of the antiserum concentration to log C50 and to log Tmax. The concentration of polyethylene glycol affected not only C50 and Tmax but also their functional dependencies on antiserum concentration. We devised two definitions of immunoturbidimetric titer and related them to the titer obtained by the single radial immunodiffusion method of Becker (Immunochemistry 1969; 6:539-46).

Apolipoprotein A-I↗
PubMed1991

Plasma protein-bound sialic acid in patients with colorectal polyps of known histology.

Protein-bound sialic acid (PBSA) was measured in serial plasma specimens from 62 healthy subjects, 48 patients with colorectal polyps, and 30 patients with colorectal adenocarcinomas. The mean plasma PBSA concentration in healthy smokers was significantly greater than that in healthy nonsmokers and healthy ex-smokers (P less than 0.0001). Villoglandular polyps were associated with higher plasma PBSA values than were the most benign hyperplastic polyps (P less than 0.025). Patients with the most neoplastic villoglandular and villous polyps had significantly greater (P less than 0.010-0.050) plasma PBSA values than healthy subjects. Polypectomy decreased the mean PBSA value significantly to the mean value for healthy subjects only for patients with villoglandular (P less than 0.010) or villous (P less than 0.050) polyps. Colorectal cancer patients had mean plasma PBSA concentrations significantly greater than those for the healthy subjects (P much less than 0.001) and the polyp patients (P much less than 0.001). Surgery significantly reduced (P less than 0.025) the mean PBSA value for the cancer patients to the mean PBSA value observed for the healthy subjects.

Adenocarcinoma↗
PubMed1991

Carcinoembryonic antigen in serum of patients with colorectal polyps: correlation with histology and smoking status.

To measure the concentration of carcinoembryonic antigen (CEA) in serial serum specimens of 47 healthy subjects and in serial sera of 59 patients with colorectal polyps of confirmed histology, obtained before or after (sometimes both) polypectomy, we used the Roche EIA and the Hybritech Tandem-E double monoclonal immunoenzymometric assays. Both methods gave comparable results for the healthy subjects but discordant values for some polyp patients. The Tandem-E test gave increased CEA results more frequently for two groups of polyp patients, the group of ex-smokers with neoplastic polyps (n = 14) and the group of smokers (n = 20). Smokers had significantly greater (P less than 0.025) mean concentrations of serum CEA than did nonsmokers, irrespective of whether they were healthy or had colorectal polyps. Smokers with recurrent polyps demonstrated significantly greater (P less than 0.050) mean concentrations of serum CEA than did smokers with a first occurrence of polyps. Polypectomy was followed by statistically significant decreases (P less than 0.050) of mean concentrations of serum CEA, primarily in polyp patients who were smokers. However, although CEA increases occurred frequently in polyp patients who smoked, these abnormalities did not fully correlate with polyp histology.

Adult↗
PubMed1989

Pancreatic oncofetal antigen and carbohydrate antigen 19-9 in sera of patients with cancer of the pancreas.

Pancreatic oncofetal antigen (POA) and carbohydrate antigen 19-9 (CA 19-9) were measured in the sera of 23 patients with cancer of the pancreas to determine the true positive rates of these cancer markers. In one group of unselected pancreatic cancer patients (n = 9), both tests showed above-normal results in three patients and both gave values that were within reference limits in three other patients. Two of the three remaining patients had increased CA 19-9 but normal POA values, and one patient had increased POA but normal CA 19-9 concentrations in serum. In another group of 14 pancreatic cancer patients, selected on the basis of increased concentrations of POA in serum, the CA 19-9 values were increased in eight. In four patients who had progressive disease, the concentrations of both markers increased with time in one patient, only POA in one, and only CA 19-9 concentration in another. (The fourth patient had increased but stable concentrations of POA and CA 19-9 in serum.) These data suggest that serum POA and CA 19-9 measurements should be used in combination in the evaluation of patients with cancer of the pancreas.

Adenocarcinoma↗
PubMed1989

Methods for determining "reference changes" from serial measurements: plasma lipid-bound sialic acid.

Lipid-bound sialic (neuraminic) acid (LSA) was measured in EDTA-treated plasma of 26 healthy subjects at three-month intervals for up to one year. The change in LSA concentration for consecutive measurements ranged from -54 to 42 mg/L (mean, -2.1 mg/L; SD, 19.6 mg/L; n = 56). The "reference change" for plasma LSA (+/- 2 SD), calculated from distribution of the differences, was +/- 39 mg/L. The 88th percentile of the intra-individual variance was 338 mg2/L2 and the mean variance was 159 mg2/L2. Using the homeostatic, autoregressive time-series model, a reference change of +/- 51 mg/L between two consecutive measurements was determined to be statistically significant (i.e., expected by chance no more than 5% of the time) in 88% of the healthy subjects. Only 73% of the healthy subjects would have had intra-individual variances corresponding to the reference change of +/- 39 mg/L according to the autoregressive model. The concentration of LSA in plasma was significantly decreased upon surgery in five of 10 patients with colorectal adenocarcinomas of Dukes stages A-C when we used +/- 39 mg/L as the reference change, but in only two of the 10 when we used +/- 51 mg/L as the reference change.

Adenocarcinoma↗
PubMed1987

A double-monoclonal immunoenzymometric assay for alpha 1-fetoprotein modified for increased analytical precision.

We modified a one-step, two-site, double monoclonal immunoenzymometric assay (Abbott Laboratories) for serum alpha1-fetoprotein (AFP) to increase its sensitivity and improve test precision at the low end. We increased sample size, incubation interval, and reaction time and temperature, and decreased the final reaction volume. Interassay CVs for the modified method ranged from 6.2 to 8.0% for mean concentrations of AFP in serum of 5.2 to 34.2 micrograms/L--substantially better than those for the unmodified monoclonal method--and agreed well with those of the comparison method (modified Abbott polyclonal immunoenzymometric assay). AFP values by the modified monoclonal procedure (y) correlated well with results by the polyclonal method (x): y = 0.983x + 1.84 micrograms/L (r = 0.927, n = 59). The detection limit of the modified monoclonal test was 0.2 microgram/L, as compared with 1.0 and 1.4 micrograms/L, respectively, for the modified polyclonal and the unmodified monoclonal procedures. We recommend using the modified monoclonal method for monitoring cancer patients with low tumor burden.

Antibodies, Monoclonal↗
PubMed1986

Formic and lactic acidosis in a fatal case of methanol intoxication.

A 33-year-old white man was admitted to the University of Utah Hospital after about 30 h of various symptoms, including blurred vision and (eventually) severe left flank and back pain. Upon admission, his serum pH was 6.80 and serum bicarbonate concentration (calculated from pCO2 and pH) was 3.9 mmol/L. The etiology for the acidosis became apparent 10 h after admission, when assay of the serum prepared from a blood specimen obtained at admission revealed a methanol concentration of 74 mmol/L (2.4 g/L). At this time the patient was placed on hemodialysis and intravenously infused with sodium bicarbonate. The methanol concentration in serum had decreased to 21 mmol/L 2 h later. Formate and lactate concentrations were, respectively, 10 and 23 mmol/L in serum sampled 4.5 h after hospitalization, at which time serum pH was 6.91 and bicarbonate concentration 7 mmol/L. The patient eventually died with extensive neuropathy.

Acid-Base Equilibrium↗
PubMed1985

A prospective study of myocardial damage in electrical injuries.

A prospective study was undertaken to determine the incidence of possible myocardial damage following electrical injury. Sixteen patients with non-flash electrical injuries were assessed utilizing serial electrocardiograms (ECG), creatine kinase (CK) and MB creatinine kinase (MB-CK) determinations, technetium 99m stannous pyrophosphate scans, and 24-hour Holter monitors. Results showed that five patients (31%) had abnormal ECG, nine patients (56%) had elevations of the MB-CK isoenzyme, and one patient had a transiently abnormal Holter monitoring. No patient had an abnormal technetium pyrophosphate cardiac scan. Of the nine patients with elevated MB-CK levels, only two had abnormal ECG. None of the patients had clinical evidence of cardiac dysfunction. These results indicate a poor correlation of elevated MB-CK levels with ECG abnormalities, and demonstrate a relatively low incidence of myocardial damage in association with electrical injuries.

Adolescent↗
PubMed1985

Effects of glycine on hemodynamic responses and visual evoked potentials in the dog.

To study the potential contribution of glycine toxicity in the transurethral resection syndrome, we evaluated hemodynamic and visual evoked potential responses to glycine infusion (1 g/kg) in 22 dogs anesthetized with halothane (1.0-1.2% end tidal. Three dogs received 5% glucose in normal saline without glycine; three received arginine (4 mg/kg) in normal saline without glycine; three received arginine (4 mg/kg) in normal saline without glycine; 10 received glycine (1 g/kg), then arginine (4 mg/kg) 120 min after the completion of glycine infusion; and six received arginine 30 min after the completion of glycine infusion. Arginine was infused to evaluate potential antagonistic effects of glycine toxicity. Blood levels of glycine, ammonia, arginine, urea, and formate were determined after infusions of glycine or arginine. All animals received about 5 ml X kg-1 X hr-1 of normal saline during the 2-4 hr of study. Immediately after glycine infusion, cardiac output increased 57%, whereas systemic vascular resistance and mean arterial pressure decreased 32% and 8%, respectively. Later cardiac output and mean arterial pressure were 41% and 18% less than control levels, whereas systemic vascular resistance returned to control levels. Both amplitude and latency of visual evoked potential waveforms were altered in the animals receiving glycine infusion but not in the control animals. These responses were associated with elevations of blood glycine (149 +/- 5 to 9591 +/- 809 microM/L, mean + SEM) and blood NH3 (10.5 +/- 2.8 to 100.0 +/- 13.6 microM/L), but not with formate levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1984

Turbidimetric measurement of total urinary proteins: a revised method.

A turbidimetric method for the determination of total urinary proteins is proposed that uses a specimen blank for each urine. The precipitant, trichloroacetic acid (TCA), is introduced into the blank and the sample in the same amount. The blank is the supernatant of the TCA-treated urine for each specimen. Turbidity is measured by reading the 420-nm absorbance 35 minutes after the TCA addition when the turbidity curves for most urine samples plateau. This improved method was compared with an established procedure that uses water to prepare the blanks and that measures turbidity 5 minutes after the TCA addition. Of the 69 urine specimens that were analyzed by the two methods, the revised procedure yielded higher values (greater than or equal to 150%) for 5 samples, while 21 samples had lower values (less than or equal to 50%). In the latter group, four cases would have been classified erroneously as having significant proteinuria by the established method.

Humans↗
PubMed1984

Formate concentrations in a case of methanol ingestion.

An eight-month-old infant ingested at least 3.5 g of methanol when he accidentally received 5 mL of amoxicillin suspended in 70% methanol. The serum methanol concentration 8 h later was 9.7 mmol/L (310 mg/L) and the formate concentration 23 mmol/L (1.0 g/L). At 18 h after the ingestion, total CO2 had decreased to 6.8 mmol/L. Throughout the second day, 21-32 h after the ingestion, the methanol concentration was 2.8-3.4 mmol/L (90-110 mg/L) and that of formate was 31-33 mmol/L (1.4-1.5 g/L). On the third day, 46 h after the ingestion, methanol was not detected and the formate concentration had declined to 16 mmol/L (720 mg/L). The patient was treated with activated charcoal 7 h after the ingestion and with ethanol, administered both orally and intravenously, 21 h after the ingestion. No abnormalities of the infant's eyes were noted upon ophthalmological examination approximately 55 h after the incident.

Adult↗
PubMed1984

Creatine kinase and lactate dehydrogenase isoenzymes in serum of patients suffering burns, blunt trauma, or myocardial infarction.

Medical records of 53 burn and trauma patients were reviewed to assess the possibility of myocardial damage. Except for electrophoretically detectable creatine kinase MB isoenzyme, none showed evidence of myocardial injury. Lactate dehydrogenase isoenzyme tests, electrocardiograms, myocardial pyrophosphate scans, clinical course, and results of (two) autopsies were all negative for myocardial necrosis or ischemia. Types of patient, number, mean peak value (U/L) for serum creatine kinase, and ranges of percentage MB isoenzyme were as follows. Burns from direct electrical contact: 28, 16 600, 0-29; electrical flash or other thermal burns: 10, 4340, 0-22; blunt trauma (mostly from automobile accidents): 15, 3430, 0-18; myocardial infarction: 57, 1520, 4-46. Evidently creatine kinase MB isoenzyme is nonspecific in burn and trauma patients and should not be the only test result used to assess myocardial involvement.

Adolescent↗