Physiological Fluids or Tissues

FIGURE 14.3 (a) Achiral separation of NBD-alanine in the rat cerebrum, (b) The chiral 

Amino Acid Mode3 Achiral column(s) Chiral column Precolumn derivitization References 

Glutamic acid PO Cig y-Cyclodextrin (Cyclobond II) Yes Rundlett and Armstrong, 1994 

Leucine RP Cig Chiral crown ether (Crownpak CR+) No Armstrong et al. (1991, 193c) 

---

Except for bulk drug substances, samples can rarely be analyzed directly following simple preparation steps. In many cases, an active ingredient is found in a formulated form or in a physiological fluid or tissue. Likewise, interferences associated with the matrix and the presence of possible degradation products, metabolites, and other closely related compounds mean the target analyte is often highly diluted. Also, an analyte may be difficult to detect. Effective sample preparation steps serve up to three broad purposes (1) eliminate and/or minimize possible interferences, (2) concentrate the sample, and (3) render the analyte of interest into a more easily detectable form. 

The advances in sample fractionation methods, sample derivatization approaches, and the instrumentation of GC and GC/MS, in particular, are fundamental to metabolic profile research. Biological variation that is inherent to the samples of physiological fluids or tissues should not be obscured by an excessive imprecision of measurement techniques. Thus, reliable sampling and sample treatment procedures (including as much automation as is feasible) should precede the use of sophisticated GC and GC/MS techniques. 

Numerous applications are now encountered where FA chromatographic profiles of a human physiological fluid or tissue are correlated to certain pathological conditions. A few representative examples will now be mentioned that include both free (non-esterified) FA and the saponified lipids. The identification of a methyl-branched FA (phytanic acid) in plasma of the patients with Refsum s disease [360] is now a widely known example of the power of GC in studying various metabolic defects. The profiles of FA from brain ti.ssue lipids were investigated for various neurological disorders [361,362] and in experimental animals [363]. Tichy et al. [364] determined FA in different lipids isolated from the cerebrospinal fluid while the FA profiles in cerebrospinal fluid differ from those in blood serum, no obvious correlations between the FA composition and human neurological complications were established at this time. 

The determination of the total platinum content in physiological fluids and tissues, both during clinical treatment or after environmental exposure, requires instrumental techniques of sufficient DLs and selectivities. ICP MS provides the most attractive DLs for platinum in biological samples, for example, 7.50 ng/L in human plasma ultrafiltrate after chemotherapy with cisplatin, carboplatin, and oxaliplatin [119] 0.1 pg/mL in blood, serum, and ultrafiltrate samples after chemotherapy with oxaliplatin and 5-fluorouracyl [120] 26 pg/g in DNA isolated from cancer ovarian cells after different exposure times and concentrations of cisplatin [121] and 0.75 pg in DNA extracts from peripheral blood mononuclear cells and tissues from patients treated with cisplatin [122] and 1.0 pg/L in serum, 0.1 pg/L in ultrafiltrate, and 2 pg/L in urine [123]. The ICP MS technique allowed detection of physiological levels of ft in the tmexposed human body 0.3-1.3 ng/L in blood (DL of 0.3 ng/L) [46] 0.48-7.7 ng/L in urine (DL of 0.24 ng/L) [47] and 0.778 ng/g... 

The major application described in the James-Martin landmark paper on gas-liquid chromatography is the separation and quantitation of fatty acids (FA). Indeed, it has remained as one of the major applications to this date. It has been estimated [350] that some 25% of all papers published in the field of GC involve, in one way or another, FA or their derivatives. A vast range of samples have been analyzed for FA animal and plant oils, foodstuffs, bacterial products, glandular secretions of animals, and various physiological fluids and tissues, just to mention a few. As more and more information is being sought concerning the composition of various lipids, the applications are expected to increase even further in the future. 

Optical sensors have been used in many ways to detect physiological variables both in vitro and in vivo. The most frequent biomedical application involves the use of fiber optics within an interluminal catheter or tissue probe with some sort of optical indicator at or near its distal tip. This indicator communicates with body fluids or tissues through a membrane permeable to the analyte but not the indicator so the latter remains in the sensor. The intensity of the light produced or modulated by the indicator is determined by optoelectronic systems back at the proximal end of the catheter or probe. Such devices have many applications in clinical medicine but are particularly important in critical care medicine. 

The direct quantitative analysis of expired air, body fluids, or tissue for the presence of the hazardous agent or its metabolites and/or evidence of biologic impairment quantified by the use of physiologic, psychometric, or biochemical tests. 

Where die connection between a vitamin and a disease is less transparent, a wide field remains open for the discovery of meaningful correlations between vitamin content of body fluids and tissues and physiologic or pathologic events. 

The concentration of fluoride in nails and hair appears to be proportional to intake over longer periods of time, taking into account their growth rate [100-103]. Exposure to fluoride may occur in the local environment at the place of residence or via occupational exposure. Daily intake from food, water, dentifrices or fluoride supplements also contributes. The major advantage of nails and hair over fluids and tissues as biomarkers for fluoride exposure is that they can easily be obtained in a non-invasive manner. In contrast to plasma, saliva and urine, whose fluoride concentrations provide a snapshot at a certain point of time and are subject to change due to recent fluoride intake and certain physiological variables, the concentration of fluoride in nails and hair is cumulative and reflects the average level of intake over a time period, but depends on how often the nails are clipped or hair cut. 

Cmde enzyme extracts are often unsuitable for therapeutic uses because of their antigenicity, contamination with endotoxins, and rapid inactivation under physiological conditions or in fluids intended for intravenous infusion over several hours. When the enzyme used is a foreign protein, it can eHcit an immune response that alters the clearance rate or induces severe allergic reactions in the host. After an intravenous injection of an enzyme, its activity in plasma decreases with time due to distribution to other fluids and tissues, and as a consequence of proteolysis or excretion. Distribution is related to molecular size, charge, and HpophiHcity surface charges attributable to the availability of free amino, amido, or carboxyl groups may affect the rate of inactivation of some enzymes. 

Hyaluronan (HA) is a component of every tissue or tissue fluid in higher animals. The highest concentrations are found in cartilage, vitreous humor, and umbilical cord and even blood contains some HA. At physiologic pH, the molecule has been shown to adopt a helical structure and therefore the molecule can be modeled as a series of helical segments that are connected with flexible segments. However, based on results of solution studies, the molecular structure of HA appears to be more complicated. 

Since iron carriers of the host become ineffective in dead tissues, the retention of physiological conditions in isolated fluids and tissues is of crucial importance in studies of the microbial quest for iron. Usually, the maintenance of excised tissues or blood at 3°C during the prepara-... 

The underlying concept in biomarkers is that the selected measurement endpoints (typically comprised of biochemical and physiological responses) can provide sensitive indexes of exposure or health effects other than death. Measurements of body fluids, cells, or tissues can indicate (in cellular or sub-cellular terms) the relative magnitude of chemical exposure or organism response. 

The free nucleotides, nucleosides, and bases which are present in physiological fluids result from the catabolism of nucleic acids, enzyme-catalyzed degradation of bodily tissues, anabolic pathways such as the de novo or salvage pathways, or dietary intake. 

---