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Biomedical subjects

K S Subramanian

Publications and source records attributed to K S Subramanian.

At least 37 records · Page 2Linked to original sources
PubMed1987

Modified auditory brainstem responses (MABR): Part I--Rationale and normative study.

Binaural, rapid rate, ABR stimulation at four intensity levels (MABR) as well as ABR at two intensity levels were carried out in 35 normal subjects. Latency and amplitude relationship with stimulus intensity of wave V of the MABR was extensively studied in these subjects. MABR recording is a rapid, sensitive, non-invasive screening method readily done at the intensive care bedside. Less than 10 minutes is required in addition to the ABR examination time. Normality of the MABR potentials implies a high degree of peripheral auditory and brainstem functional integrity, augmenting information gained with standard ABR technique. Only clinical trials can decide if MABR sensitivity will exceed that of the ABR and prove helpful to diagnosis and patient care.

Acoustic Stimulation↗
PubMed1986

Electrocochleography recorded non-invasively from the external ear.

A method is described to record cochlear evoked potentials in humans (ECochG) with a low impedance electrode on the external ear near the opening of the external auditory canal. A piezoelectric click stimulus was delivered to the ear through a polyethylene tube creating diminution of stimulus artifact and a signal delay. Wave forms resembling the cochlear microphonic (CM), summating potential (SP) and the eighth nerve action potential (N1) were differentially accentuated by changes in stimulation and recording parameters. The addition or subtraction of condensation and rarefaction click wave forms further clarified the N1 and SP, or the CM potential, respectively. These responses can be recorded with most contemporary evoked response equipment. This non-invasive method of ECochG lends itself well to the study of hearing loss and possibly other neurologic disorders, and may complement BAER examination especially when wave I is poorly delineated.

Audiometry, Evoked Response↗
PubMed1985

Kidney and liver levels of some major, minor and trace elements in two Ontario communities.

The contents of Ag, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Se, Sr, Th, Ti and Zn in 143 autopsied liver and kidney specimens from two Ontario communities (Kingston and Ottawa) were determined using the techniques of inductively-coupled plasma--atomic emission spectrometry, and electrothermal atomization--atomic absorption spectrometry coupled with hydride evolution (As, Se), reduction--aeration (Hg), or solvent extraction (Pb). The majority of samples came from individuals older than 50 y. In general, the data for the various elements were independent of age or sex but showed some dependence on location for elements such as Cu, Fe, K, Mg, Mn, Na, P, Se and Zn. Despite these differences the elemental values of the liver and kidney samples from both the communities were within the normal range.

Adolescent↗
PubMed1985

Preconcentration of cadmium, chromium, copper and lead in drinking water on the polyacrylic ester resin, XAD-7.

The conditions (e.g. pH, resin, particle size, foreign ions) affecting the uptake of Cd(II), Cr(III), Cu(II) and Pb(II) from aqueous solution by the SM-7 (also called XAD-7) resin, were studied. Based on these studies, a two-column method was developed to overcome the effect of complexation by humic substances. The method was successfully tested with the NBS multielement water standard, SRM 1643a, and was subsequently applied to enrich Cd(II), Cr(III), Cu(II) and Pb(II) in 15 drinking water samples from Hamilton, Ontario. The metals were determined using graphite furnace atomic absorption spectrometry. The results for the drinking water samples showed that leaching of copper and lead occurred from the distribution system.

Acrylic Resins↗
PubMed1984

Arsenic in Nova Scotian groundwater.

The concentration of total soluble inorganic arsenic (i.e. arsenate plus arsenite) was measured in duplicate well water samples of 94 residents in Halifax County, N.S. An ammonium pyrrolidinedithiocarbamate-methyl isobutyl ketone graphite-furnace atomic absorption spectrophotometric procedure and also an automated hydride-evolution electrothermal-atomisation atomic-absorption spectrophotometric method were used to monitor the arsenic level in the ground water supplies. Of the 94 samples analyzed, 66 samples (70%) exceeded the Canadian maximum acceptable drinking water guideline of 50 ng As/ml.

Arsenic↗
PubMed1984

Nuclear scintigraphy as a diagnostic tool in venous aneurysms.

Aneurysmal dilatation in the low pressure system of internal jugular vein is rare. A case of an aneurysm of the right internal jugular vein, is presented, which was initially diagnosed by nuclear scintigraphy and confirmed by angiography. Clinical presentation, classification, etiology, pathogenesis, and diagnostic modalities of the disease are also reviewed.

Aneurysm↗
PubMed1983

Blood levels of cadmium, copper, lead and zinc in children in a British Columbia community.

The levels of Cd, Cu, Pb and Zn were measured in duplicate whole blood samples of 946 apparently normal children ranging in age from 2 years to 12 years and living in Kamloops, British Columbia, Canada. The metals were determined using atomic absorption spectrometry: graphite furnace AAS for Cd and Pb, and flame AAS for Cu and Zn. The median and extreme values expressed as milligram of metal per litre of whole blood for the total population were: Cd less than or equal to 0.0005, Cu 1.11 (0.69-1.78), Pb 0.112 (0.020-0.400), and Zn 4.30 (2.10-6.53). No significant variations were noted in the median metal values either with age or with sex. The median Cu, Pb and Zn values were within the normal range.

Air Pollutants, Occupational↗
PubMed1982

Simultaneous determination of 20 elements in some human kidney and liver autopsy samples by inductively-coupled plasma atomic emission spectrometry.

The argon supported inductively coupled plasma--atomic emission spectrometer (ICP--AES) is found to be an attractive analytical tool for the simultaneous multi-element determination of major, minor and trace elements in human liver and kidney specimens. The sample is digested with a mixture of HNO3--HClO4. The damp residue is taken up in HCl, aspirated into the plasma and the resulting emission signals are detected by a polychromator where the analytical lines of the 20 elements determined are included as fixed channels. The method is rapid, precise, sensitive, less subject to interferences and cost-effective. A total of 20 elements in about 40 autopsy samples of human kidney (cortex and medulla) and liver taken from Canadian adults living in the Great Lakes Region of Ontario were determined using the wet digestion-ICP--AES technique.

Adult↗
PubMed1981

Survey for cadmium, cobalt, chromium, copper, nickel, lead, zinc, calcium, and magnesium in Canadian drinking water supplies.

A second national survey was done to ascertain the levels of Cd, Co, Cr, Cu, Ni, Pb, Zn, Ca, and Mg in Canadian drinking water supplies. Raw, treated, and distributed water samples collected from 71 municipalities across Canada were analyzed both by atomic absorption spectrophotometry using the direct method and by an APDC-MIBK extraction procedure. As in the first national survey, the amounts of trace metals found in the 3 types of water samples were essentially the same. Contamination of the water supplies with these metals except Cu and Zn was minimal during treatment and distribution. For Canadian drinking water, the median and extreme values expressed as ng metal/mL water were: Cd less than or equal to 0.02 (less than or equal to 0.02-0.07), Co less than or equal to 2.0 (less than or equal to 2.0-6.0), Cr less than or equal to 2.0 (less than or equal to 2.0-4.1), Cu less than 10 (less than or equal to 10-900), Ni less than or equal to 2.0 (less than or equal to 2.0-69.0), Pb less than or equal to 1.0 (less than or equal to 1.0-79.7), and Zn less than or equal to 10 (less than or equal to 10-750). Hardness values as mg CaCO3/L ranged from 6.7 in St. John's, Newfoundland, to 328.3 in Portage La Prairie, Manitoba. The median values for the Canadian drinking water supplies were well below the maximum permissible limits set by Health and Welfare Canada and the World Health Organization.

Canada↗
PubMed1981

A rapid electrothermal atomic absorption spectrophotometric method for cadmium and lead in human whole blood.

A rapid graphite-furnace atomic absorption spectrophotometric procedure is described for determining cadmium and lead in heparinized human whole blood. A known aliquot of the blood sample is diluted fivefold with an aqueous solution composed of 5 g each of diammonium hydrogen phosphate and Triton X-100 per liter, the solution is vigorously agitated, and a 10-microL aliquot is injected into a pyrocoated graphite tube under optimized instrumental conditions. Values for Cd and Pb in the sample are obtained by direct comparison to linear working curves prepared from aqueous standards of the metals in the diammonium hydrogen phosphate-Triton medium; there is no need to use the method of standard addition or matrix-matched calibration curves. Also, the method is free of matrix effects. At least 30 samples can be analyzed per hour. The rapidity, simplicity, and sensitivity of the method make it attractive as a screening technique for routine environmental surveillance involving large throughput of samples.

Cadmium↗