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Biomedical subjects

S K Aggarwal

Publications and source records attributed to S K Aggarwal.

At least 37 records · Page 2Linked to original sources
PubMed1996

Combined left-sided recurrent laryngeal and phrenic nerve palsy after coronary artery operation.

BACKGROUND: Ice/saline slush used along with cold cardioplegia for heart arrest in cardiac operations can cause hypothermic damage to certain structures, an important one being the left phrenic nerve, damage of which results in raised left hemidiaphragm and delayed recovery of the patient. In coronary artery bypass grafting, opening of the pleura and collection of the ice/saline slush in the pleural cavity increases the incidence of injury. METHODS: Three of our nonconsecutive patients underwent coronary artery bypass grafting with cold cardioplegia and open pleura, with collection of ice/saline slush in the pleural cavity for a sufficiently long time. RESULTS: Simultaneous involvement of left recurrent laryngeal nerve along with left phrenic nerve was found in all patients without any concurrent topical injury around the larynx. the recurrent laryngeal nerve took 8 to 10 months to recover. CONCLUSIONS: The left recurrent nerve as it arches around aorta lies in the thorax very close to the parietal pleura and may be prone to hypothermic injury by ice/slush collecting in the pleural cavity during cardiac operations. Judicious use of ice/saline slush had helped in eliminating the problem to some extent.

Aged↗
PubMed1996

Contribution of the S4 segment to gating charge in the Shaker K+ channel.

Voltage-activated ion channels respond to changes in membrane voltage by coupling the movement of charges to channel opening. A K+ channel-specific radioligand was designed and used to determine the origin of these gating charges in the Shaker K+ channel. Opening of a Shaker K+ channel is associated with a displacement of 13.6 electron charge units. Gating charge contributions were determined for six of the seven positive charges in the S4 segment, an unusual amino acid sequence in voltage-activated cation channels consisting of repeating basic residues at every third position. Charge-neutralizing mutations of the first four positive charges led to large decreases (approximately 4 electron charge units each) in the gating charge; however, the gating charge of Shaker delta 10, a Shaker K+ channel with 10 altered nonbasic residues in its S4 segment, was found to be identical to the wild-type channel. These findings show that movement of the NH2-terminal half but not the CO2H-terminal end of the S4 segment underlies gating charge, and that this portion of the S4 segment appears to move across the entire transmembrane voltage difference in association with channel activation.

Animals↗
PubMed1996

Cocaine-associated intracranial hemorrhage: absence of vasculitis in 14 cases.

Complications associated with the use of cocaine are varied, and include cerebral hemorrhage and ischemia, with vasculitis and vasospasm as possible etiologies. We reviewed selected brain samples from 14 autopsy cases of cocaine-related cerebrovascular disease. Intracerebral or subarachnoid hemorrhage was present in 12 cases. Intracranial arterioles were either normal or showed nonspecific changes. From these observations, we suggest that intracranial hemorrhages occur in the absence of readily detectable vascular abnormalities.

Adult↗
PubMed1996

Determination of blood lead by electron-capture negative chemical ionization gas chromatography-mass spectrometry.

An electron-capture negative chemical ionization (NCI) gas chromatography-mass spectrometry (GC-MS) method for determination of lead (Pb) in blood samples is described. Extraction of Pb from the sample does not involve hot digestion but is based on treatment at ambient temperature. The blood sample is supplemented with a known amount of internal standard (204Pb) for isotope dilution and is treated with concentrated nitric acid. After adjusting the pH to 7, the Pb is extracted into toluene as the pyrrolidine-dithiocarbamate chelate. Samples are then derivatized with 4- fluorophenylmagnesium bromide to form Pb(FC6H4)4. The use of NCI offers enhanced sensitivity (by 75-fold better than previously used electron ionization), gives good precision and accuracy, and has no observable memory effect. The isotope dilution GCoff methodology typically agreed within 2-3% of expected values for the College of American Pathologists blood Pb specimens and the National Institute of Standards and Technology Standard Reference Material 955a.

Gas Chromatography-Mass Spectrometry↗
PubMed1995

Capillary gas-liquid chromatography of 6-hydroxylated bile acids.

Gas-liquid chromatographic separation of several bile acids with a hydroxyl group at C-6 is described on two capillary columns, CP-Sil-19 CB and CP-Sil-5 CB. The gas-liquid chromatographic retention indices of bile acids with 6 alpha- and 6 beta-hydroxyl groups are compared with those of bile acids without the C-6 hydroxyl group and the effect of the C-6 hydroxyl group on the retention indices of bile acids is determined. Both 6 alpha- and 6 beta-hydroxyl groups increase the retention index of a bile acid. The retention indices of 6 alpha- or 6 beta-hydroxyl derivatives of chenodeoxycholic acid were found to be higher than those of the corresponding 6-hydroxy derivatives of cholic acid on the CP-Sil-19 CB column but lower on the CP-Sil-5 CB column. Although all 6-hydroxylated derivatives of lithocholic, chenodeoxycholic and cholic acids were not completely resolved on either column alone, combining the two columns resulted in the complete separation of all these compounds.

Bile Acids and Salts↗
PubMed1995

Thoracic radicular symptoms in amyotrophic lateral sclerosis.

We report 4 patients with amyotrophic lateral sclerosis (ALS) complaining of thoracic radicular symptoms. We postulate that in some patients paraspinal muscle weakness can result in an increased thoracic kyphosis, possibly producing traction on the thoracic roots.

Aged↗
PubMed1995

Cisplatin and carboplatin-mediated activation of murine peritoneal macrophages in vitro: production of interleukin-1 alpha and tumor necrosis factor-alpha.

Analysis of tissue culture supernatants collected from cisplatin (10 micrograms/ml) and carboplatin (50 micrograms/ml)-treated macrophages show enhanced activity of interleukin-1 alpha and tumor necrosis factor-alpha. Cytotoxicity of these supernatants was demonstrated using mouse sarcoma-180 cells. These results demonstrate the ability of cisplatin and carboplatin to enhance the immune system suggestive of yet another mechanism of their action in the regression of tumors.

Animals↗
PubMed1994

Determination of tellurium in urine by isotope dilution gas chromatography/mass spectrometry using (4-fluorophenyl)magnesium bromide as a derivatizing agent and a comparison with electrothermal atomic absorption spectrometry.

The antitumor drug AS-101 [ammoniumtrichloro (dioxoethylene-O,O')tellurate(IV)] is the first tellurium-containing compound that has been identified as possessing immunomodulating properties and minimal toxicity. We have developed a stable isotope dilution gas chromatography/mass spectrometry method using 120Te as an internal standard and (4-fluorophenyl)magnesium bromide as a derivatizing agent for Te determination in urine. The urine samples were digested using HNO3 + H2O2 prior to derivatization with lithium bis(trifluoroethyl)dithiocarbamate at a pH of 3. The trifluorodiethyldithiocarbamate of tellurium was reacted with the Grignard reagent in anhydrous diethyl ether to obtain Te-(FC6H4)2 for GC/MS analysis. All isotope ratio measurements were made by selected ion monitoring with a Finnigan MAT 8230 organic mass spectrometer using a 10-m fused silica capillary column. Overall percision values for the five major Te isotopes relative to 130Te were 0.6-3.1% when 10-ng samples of chelated Te were analyzed. No appreciable memory or carry-over effect was observed when two synthetic mixtures differing in 120Te:130Te ratios by a factor of 50 were sequentially analyzed. The isotope dilution GC/MS method was validated by determining Te in urine samples and comparing the values with electrothermal atomic absorption spectrometry. Te concentrations were determined in the 100-500 micrograms/L range with CVs of 1-4%.

Gas Chromatography-Mass Spectrometry↗
PubMed1994

Cisplatin-induced peptic ulcers, vagotomy, adrenal and calcium modulation.

Cytochemical and autoradiographic studies in Wistar rats [Crl:(WI)BR] show that cisplatin treatment (9 mg/kg) inhibits the release of acetylcholine from the axonal endings of the stomach smooth muscle resulting in bloating of the stomach and ulceration. Cisplatin also induces corticosteroid release from the adrenal gland stimulating peptic ulceration. Vagotomy helps ameliorate the effect but not eliminate it. Calcium supplementation restores normal neuromuscular function to gastric smooth muscle, thereby eliminating the gastro-intestinal toxicity due to cisplatin.

Acetylcholinesterase↗
PubMed1994

Cisplatin and carboplatin mediated release of cytolytic factors in murine peritoneal macrophages in vitro.

The anticancer drugs cisplatin and carboplatin have been shown to activate murine peritoneal macrophages in vivo and in vitro. These activated macrophages have enhanced tumoricidal activity mediated by extension and contact formation with the tumor cells leading to an increase and transfer of lysosomes with eventual lysis of the tumor cells. Cisplatin (10 micrograms/ml) or carboplatin (50 micrograms/ml) for 2 and 24 h treatment of macrophages in vitro, in addition, show a significant increase in the release of various cytolytic factors, like hydrogen peroxide, superoxide anion, interleukin-1 alpha, lysozyme and beta-N-hexoseaminidase, that are also responsible for the destruction of tumor cells.

Animals↗
PubMed1994

The Henry Ford Hospital Headache Disability Inventory (HDI).

To quantify the impact of headache of daily living, we developed a 25-item headache disability inventory (HDI). The alpha version of the HDI (alpha-HDI) consisted of 40 items, each requiring a "yes" (four points), "sometimes" (two points), or "no" (zero points) response based on items derived empirically from case history responses of subjects with headache. From the alpha-HDI, we derived a 25-item beta version (beta-HDI) with the items subgrouped into functional and emotional subscales. The internal consistency/reliability was strong, as was construct validity. The test-retest reliability for the beta-HDI was acceptable for the total score and functional and emotional subscale scores. A 29-point change (95% confidence interval) or greater in the total score from test-retest must occur before the changes can be attributed to treatment effects. The HDI is useful in assessing the impact of headache, and its treatment, on daily living.

Adult↗
PubMed1994

Mass spectrometry of trace elements in biological samples.

Mass spectrometry is a powerful analytical tool for determining the isotope ratios and concentrations of trace elements in various samples at levels ranging from major constituents to subparts per billion. Because isotope dilution is free from matrix effects, it has the potential of being incorporated into a definitive analytical approach that can provide reference values for concentrations in physiological and pathological conditions. In addition, isotope dilution mass spectrometry results are free from the constraints of quantitative recovery of the analyte, an essential requirement in other analytical techniques that is difficult to achieve with complex biological samples. A variety of mass spectrometric approaches have been used for determining the concentration of trace elements in biological samples. The more commonly used are thermal ionization mass spectrometry, inductively coupled plasma mass spectrometry, fast atom bombardment mass spectrometry, and gas chromatography mass spectrometry. This article reviews the work on trace element determination in biological samples using different mass spectrometric techniques and highlights the experiments performed by the authors in establishing gas chromatography mass spectrometry.

Animals↗
PubMed1994

Determination of lead in urine and whole blood by stable isotope dilution gas chromatography-mass spectrometry.

A stable isotope dilution gas chromatography-mass spectrometry (GC-MS) method is described for the determination of lead (Pb) in urine and whole blood. The use of lithium bis(trifluoroethyl)dithiocarbamate Pb(FDEDTC) as a chelating agent showed strong memory effect, restricting the range of Pb isotope ratios that can be measured in unknown samples. To overcome this carryover problem, we further derivatized the Pb(FDEDTC)2 chelate with 4-fluorophenyl magnesium bromide to form Pb(FC6H4)4. The sequential analyses of solutions of natural Pb and enriched 204Pb with Pb(FC6H4)4 chelate by GC-MS demonstrated no observable memory effect. Precision and accuracy of Pb isotope ratio measurements with Pb(FC6H4)4 were established, and the isotope dilution GC-MS method was validated by determining Pb concentrations in urine standards from the National Institute of Standards and Technology, urine and blood reference materials from the New York State Department of Health, and blood Pb survey samples from the College of American Pathologists.

Calibration↗
PubMed1993

Diagnosis and management of neurocysticercosis.

Long endemic in developing countries, cysticercosis is surfacing in the United States. Diagnosis of CNS involvement has been aided by laboratory and radiologic advances. Anthelmintic agents add to treatment options.

Adult↗
PubMed1993

Determination of platinum in urine, ultrafiltrate, and whole plasma by isotope dilution gas chromatography-mass spectrometry compared to electrothermal atomic absorption spectrometry.

Isotope dilution gas chromatography-mass spectrometry (GC-MS) and electrothermal atomic absorption spectrometry (EAAS) are compared for platinum (Pt) determination in urine, plasma ultrafiltrate, and plasma samples from a patient undergoing cisplatin therapy. The isotope dilution GC-MS method is based on the use of lithium bis(trifluoroethyl)dithiocarbamate as a chelating agent and enriched 192Pt as an internal standard. Pt isotope ratios were measured using a Finnigan MAT 8230 organic mass spectrometer, and Pt concentrations were calculated from different sets of isotope ratios in the molecular ion of the Pt-chelate. In the EAAS method, Pt concentrations were determined using three different approaches. These were: (i) calibration curve based on aqueous standards containing Pt in 10% HCl, (ii) standard addition, and (iii) matrix digestion followed by standard addition. Good agreement was obtained for Pt concentrations determined by GC-MS and EAAS in urine samples while there were significant differences in Pt concentrations of ultrafiltrate and whole plasma samples by the two methods. Discussion of possible reasons for these differences emphasizes the need for future critical evaluation of these methods.

Carcinoma, Squamous Cell↗
PubMed1993

Cisplatin and carboplatin induced changes in the neurohypophysis and parathyroid, and their role in nephrotoxicity.

Cytochemical and ultrastructural studies in Wistar rats [Crl: (WI)BR] show that cisplatin treatment (5-9 mg/kg) induces a release of neurosecretory granules from the neurohypophysis with a corresponding decrease in the urine output in a time and dose dependent fashion. Cisplatin induces low blood calcium and phosphate levels with a corresponding increase in the dark cells of the parathyroid gland. Injections of calcium before and during the treatment of cisplatin are effective in combating hypocalcemia, nephrotoxicity and gastrointestinal toxicity due to cisplatin. Carboplatin, a less nephrotoxic agent, does not demonstrate any of these changes.

Alkaline Phosphatase↗