Unusually high concentrations of Zn alpha 2-glycoprotein and the lack of alpha 2HS-glycoprotein in human ejaculates

Ejaculates of 132 nonvasectomized and 129 vasectomized men were assayed for their Zn alpha 2- and alpha 2HS-glycoprotein contents by radial immunodiffusion. The respective mean concentrations of Zn alpha 2-glycoprotein were 319 and 309 mg/L, respectively, but these fluids were devoid of alpha 2HS-glycoprotein. In comparison, the concentration of these two proteins in serum of normal men were 62 and 617 mg/L for Zn alpha 2- and alpha 2HS-glycoprotein, respectively. Because albumin in the ejaculates is 100-fold less concentrated than in serum, the fivefold increase in the concentration of Zn alpha 2-glycoprotein of the ejaculates represents about a 500-fold enrichment of this protein in the ejaculates over the concentration expected by comparison with albumin.

Unusually high concentrations of Zn alpha 2-glycoprotein and the lack of alpha 2HS-glycoprotein in human ejaculates

Ejaculates of 132 nonvasectomized and 129 vasectomized men were assayed for their Zn alpha 2- and alpha 2HS-glycoprotein contents by radial immunodiffusion. The respective mean concentrations of Zn alpha 2-glycoprotein were 319 and 309 mg/L, respectively, but these fluids were devoid of alpha 2HS-glycoprotein. In comparison, the concentration of these two proteins in serum of normal men were 62 and 617 mg/L for Zn alpha 2- and alpha 2HS-glycoprotein, respectively. Because albumin in the ejaculates is 100-fold less concentrated than in serum, the fivefold increase in the concentration of Zn alpha 2-glycoprotein of the ejaculates represents about a 500-fold enrichment of this protein in the ejaculates over the concentration expected by comparison with albumin.

GABAB receptor mediated effects on central respiratory system and their antagonism by phaclofen

The role of GABAB receptors in control of central respiratory system was evaluated by cycle-triggered averaging of phrenic nerve activity (PNA) of the rabbit. Blockade of GABAB receptors of the caudal brainstem by intracerebroventricular administration of phaclofen augmented PNA, decreased the duration of inspiration and to about the same extent increased the duration of expiration thus unmasking intrinsically active GABA. Analogously, stimulation of brainstem GABAB receptors by exogenous baclofen decreased PNA. Preceding administration of larger doses of phaclofen could block the effects of baclofen. It is proposed that GABAB receptors are involved in tonic and phasic modulation of central respiratory activity.

Involvement of fast synaptic inhibition in the generation of high-frequency oscillation in central respiratory system

During moderate hypercapnia, spectrum analysis of efferent phrenic nerve activity (PNA) of urethane anesthetized rabbits revealed high-frequency oscillations (HFO). The spectral peak (mean frequency 111 Hz) was reversibly eliminated by the glycine receptor antagonist strychnine administered into the 4th cerebral ventricle. In contrast, blockade of brainstem GABAA receptors by bicuculline did not abolish HFO but even reinforced or induced HFO. Thus, there is evidence that fast synaptic inhibition via glycine receptors is involved in the generation of HFO within the medullary respiratory center, whereas GABA may play a modulatory role.

Spectral composition of synchronized discharge of phrenic nerve activity in the rabbit and effects of pulmonary afferents

In anaesthetized rabbits synchronization of efferent phrenic nerve discharge activity (PNA) was investigated by spectrum analysis. During hypercapnia (6-8% end-tidal CO2) in almost all animals the spectrum analysis of PNA during inspiration revealed a bimodal distribution. A broad peak was present at 45.9 +/- 7.7 Hz (MFO peak) whereas a usually well-defined peak with smaller band width was located at 100.3 +/- 17.1 Hz (HFO peak). Increase of hypercapnia promoted the peak amplitude of HFO but had no consistent effect on the amplitude of MFO. Synchronization in the HFO band gradually increased with the progress of inspiration but declined during the last third of inspiration. HFO could be demonstrated to be also present in postinspiratory activity. The amplitude of MFO slowly increased during inspiration becoming strongest at the end of inspiration. The effect of afferent inputs from pulmonary stretch receptors on synchronization of PNA was found to be very weak. Neither withholding inflation during inspiration nor bilateral vagotomy produced substantial changes of MFO and HFO. Tracheal occlusions, however, during inspiration resulted in a slight increase of the power of MFO and HFO, which mainly was due to an overall increase of power. Augmented breaths resulted in a strong shift of the HFO peak to higher frequencies which was accompanied by a dramatic increase of the peak amplitude and a decrease of the peak band width. The presumptive role of the different types of phrenic motoneurons conveying HFO is addressed.

The position of the disulfide bonds in human plasma alpha 2 HS-glycoprotein and the repeating double disulfide bonds in the domain structure

The positions of the inter- and intra-chain disulfide bonds of human plasma alpha 2 HS-glycoprotein were determined. alpha 2 HS-glycoprotein was digested with acid proteinase and then with thermolysin. The disulfide bonds containing peptides were separated by reversed-phase HPLC and detected by SBD-F (7-fluorobenzo-2-oxa-1,3-diasole-4-sulfonic acid ammonium salt) method. One inter-disulfide bond containing peptide and five intra-disulfide bond containing peptides (A-chain) were purified and identified as Cys-18 (B-chain)--Cys-14 (A-chain), Cys-71--Cys-82, Cys-96--Cys-114, Cys-128--Cys-131, Cys-190--Cys-201 and Cys-212--Cys-229, respectively. The location of the intra-disulfide bonds revealed that the A-chain of alpha 2 HS-glycoprotein is composed of three domains. Two domains were shown to possess intramolecular homology judging from the total chain length of the domains, size of the loops formed by the S--S bonds, the location of two disulfide loops near the C-terminal end of domains A and B, the distance between two S--S bonds of each domain, the amino acid sequence homology between these two domains (22.6%), number of amino acid residues between the second S--S loops and the end of domains A and B, and the positions of the ordered structures.

Disposition of [14C]-benazepril hydrochloride in rat, dog and baboon. Absorption, distribution, kinetics, biotransformation and excretion

The compound 3-[(1-ethoxycarbonyl-3-phenyl-(1S)-propyl)-amino]-2,3,4,5- tetrahydro-2-oxo-1-(3S)-benzazepine-1-acetic acid hydrochloride (benazepril.HCl, CGS 14 824 A) is an ethyl ester prodrug of the angiotensin converting enzyme (ACE) inhibitor benazeprilat (CGS 14 831). The disposition of both compounds was studied in rat, dog and baboon after peroral and intravenous dosing of 14C-labelled preparations (2.5-3 mg/kg). Perorally dosed benazeprilat was poorly absorbed in rats, whereas benazepril.HCl was well absorbed in all species. Onset of absorption of benazepril.HCl was fast. Plasma concentrations of radioactivity indicated a prolonged absorption process. Upon intravenous benazepril.HCl, plasma levels declined rapidly in all species but showed a slow terminal elimination phase. Distribution to all organs and tissues occurred rapidly and was typical for an acid compound. Passage of the blood-brain barrier and of the placenta occurred to a minimal extent. No accumulation was observed after repeated dose. Radioactivity was rapidly and completely eliminated; biliary excretion was important. In the rat, benazepril was completely hydrolysed by first pass metabolism to the pharmacologically active benazeprilat. In dog and baboon hydrolysis was incomplete and additional hydrophilic metabolites were formed also.

Influence of rubrospinal tract and the adjacent mesencephalic reticular formation on the activity of medullary respiratory neurons and the phrenic nerve discharge in the rabbit

Suprapontine brain sites acting on the central respiratory system have been demonstrated to give rise to inspiratory as well as expiratory facilitatory effects. In the present study the inspiratory inhibitory effect which has been reported in the cat to be elicited consistently by electrical stimulation of the rubrospinal tract and the adjacent mesencephalic reticular formation was examined in the urethane-anaesthetized rabbit. Stimulation of these sites with single electrical shocks of moderate intensity induced a short latency (onset after 3.0 ms) transient (duration: 29 ms) inhibition of the phrenic nerve activity (PHR). Short volleys of stimuli applied in mid- to late-inspiration led to a premature off-switch of inspiration. The extracellularly recorded discharge activity of the different types of medullary respiration-related units (RRU) reflected these alterations, accordingly. Axonal connections of RRU with mesencephalic structures were evaluated. Examination of orthodromic responses of medullary RRU to stimulation of this pathway revealed that most bulbospinal inspiratory neurons (10 out of 13) were paucisynaptically inhibited after short latency (at least 1.2 ms). The conduction time from bulbospinal inspiratory neurons to the recording site of PHR was 1.6 ms. Thus, a disynaptic pathway--including bulbospinal inspiratory neurons--is suggested inducing inspiratory inhibition 3.0 ms after single shock midbrain stimulation. This inhibition results in disfacilitation of phrenic motoneurons. The fact that extensive electrolytic lesions of the pneumotaxic center in rostral pons did not abolish the observed inspiratory inhibitions excludes these structures from being involved.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro nerve-growth-promoting activity of human plasma alpha 1-acid glycoprotein

Human plasma alpha 1-acid glycoprotein or orosomucoid (OR), and its derivatives, prepared by sequential enzymatic cleavage of the carbohydrate units, were tested for their nerve-growth-promoting activities with explants of whole dorsal root ganglia from chick embryos. The results showed that the OR derivatives with terminal galactose, N-acetylglucosamine, or mannose have marked neurite-promoting activities. These preparations at a concentration of 100 micrograms/ml are equivalent to 5% fetal bovine serum (protein concentration 3,000 micrograms/ml) in their ability to elicit extensive neurite outgrowth and collateral branching. The asialo-OR, or ASOR, is the most potent form: its activity is estimated to be 20 times higher than that of transferrin and 100 times over that of fibronectin; it is approximately 1/1,500 that of NGF. The neurite-promoting activity of OR is independent of the non-neuronal cells and their products and can be blocked by a specific antiserum against OR. The mode of action of OR on the in vitro nerve growth is discussed and the pathophysiological significance of this plasma glycoprotein is considered in light of data from recent clinical and pathological studies.

The carbohydrate composition of human serum amyloid P component

The carbohydrate moiety of human serum amyloid P component was analyzed and found to consist of equal amounts of galactose and mannose (total 4.0%), of glucosamine and galactosamine in a ratio of 7:1 (total 2.7%) and sialic acid (3.9%). It should be noted that this is the first report on the separate quantification of the neutral hexoses and the demonstration of the presence of galactosamine. The contents of glucosamine and galactosamine suggest that this protein possesses both an N- and an O-glycan.

The N- and O-linked carbohydrate chains of human, bovine and porcine plasminogen. Species specificity in relation to sialylation and fucosylation patterns

The structures of the N- and O-glycans of human, bovine and porcine plasminogen were determined by 500-MHz 1H-NMR spectroscopy. The N-glycans of all three species proved to be of the N-acetyllactosamine type differing from one another with respect to the sialylation and fucosylation patterns. In the N-glycan of human plasminogen the two antennae are sialylated with N-acetylneuraminic acid (NeuAc), whereas in the bovine counterpart both branches carry significant amounts of N-glycolylneuraminic acid (NeuGc). In porcine plasminogen the sialic acid is mainly NeuAc; the Man alpha 1----6 branch, however, is only partially sialylated. In addition, the porcine N-glycan is fucosylated to about 80% in alpha 1----6 linkage to the GlcNAc-1 residue. The O-glycans of the three species possess an identical Gal beta 1----3GalNAc core which is alpha 2----3 sialylated with NeuAc at Gal. The disialylated form, which is also present in all three species, has an additional NeuAc residue in alpha 2----6 linkage to GalNAc. Mono- and disialylated forms occur in different molar ratios in the different plasminogens: 80:20 in human, 70:30 in bovine and 50:50 in porcine. This study on the carbohydrate moiety of these three plasminogens reveals species specificity in terms of various types of microheterogeneities.

Determination of the angiotensin converting enzyme inhibitor benazeprilat in plasma and urine by an enzymic method

An enzyme inhibition assay for the angiotensin-converting enzyme (ACE) inhibitor benazeprilat is described. Plasma and urine samples were diluted and endogenous ACE was inactivated by heating. After incubation of the plasma samples with hippuryl-histidyl-leucine as substrate and blank plasma as the source of ACE, released hippuric acid was measured by high-performance liquid chromatography. Urine samples were incubated with [3H] hippuryl-glycyl-glycine and with rabbit lung extract as the source of ACE. Released [3H] hippuric acid was quantified by liquid scintillation counting. Drug standards for the standard curve were prepared in the biological matrix. A cross-check with a gas chromatographic-mass spectrometric method showed good agreement, demonstrating that this enzymic method is suitable for assessing drug bioavailability and pharmacokinetics.

A method for the quantitative analysis of nerve growth in vitro

A method is described for the quantitative analysis of the nerve-growth-promoting activity of biological molecules in tissue culture. The criteria used for the evaluation of this activity is based on the neurite length as well as the total number of neurites produced by the explant of whole dorsal root ganglia from 12-d-old chick embryos. A nerve growth index (NGI) is given to each ganglion during each of a 5-d culture period. The NGI is defined as the product of average neurite length in millimeters and the total number of neurites. We report that with increasing concentrations of fetal bovine serum, there was a proportional increase in NGI due to increased neurite density while the neurite length was not greatly affected. The NGI of several proteins with known nerve growth promoting activity, namely nerve growth factor, insulin, transferrin, and fibronectin were investigated for their activity and compared with that of fetal bovine serum.

Plasmid-mediated sucrose metabolism in Escherichia coli K12: mapping of the scr genes of pUR400

The scr genes located on plasmid pUR400 and responsible for sucrose (Scr) metabolism of Escherichia coli K12 and other enteric bacteria have been cloned on a 9.3 kb DNA fragment. The different genes were mapped by transposon insertion mutagenesis, by restriction endonuclease and deletion mapping, and the corresponding gene products were identified. Besides the known structural genes scrA, coding for an EnzymeII(Scr) (45 kD) of the phosphoenolypyruvate-dependent phosphotransferase system (PTS), and scrB, coding for a sucrose 6-phosphate hydrolase (invertase) (55 kD), two new structural genes were discovered. Gene scrK apparently codes for an intracellular and ATP-dependent fructokinase (39 kD), while scrY seems to code for a sucrose porin (58 kD) in the outer cell membrane. No genes for an Enzyme III(Scr) of the PTS or for (a) glycosyltransferase(s) were detected. The four genes form an scr operon (gene order, scrK scrY scrA scrB, transcription from K to B), regulated by a repressor (gene scrR, 37 kD) and inducible by sucrose, fructose and fructose-containing oligosaccharides.

Human serum alpha 2HS-glycoprotein modulates in vitro bone resorption

We previously isolated a family of bone-resorbing proteins from human cancer ascites fluid and established that the three purified bone-resorbing proteins were chemically and immunochemically related to each other and to alpha-2HS glycoprotein (alpha 2HS). After this finding we purified the normal human serum counterpart of these ascites proteins and studied its effects on bone resorption. The bone-resorbing properties of normal human serum alpha 2HS were examined in vitro over a wide dose range. This normal human serum glycoprotein had a biphasic effect on 45Ca2+ release from bone. More specifically, this protein stimulated bone resorption at the lower concentrations tested, with a maximum effect [treated over control ratio of 2.5 +/- 0.30 (+/- SE); P less than 0.01] at 40 micrograms/mL. In contrast, at doses above 40 micrograms/mL, a sharp decline in calcium mobilization occurred, with a return to baseline occurring above 80 micrograms/mL. These results suggest that serum alpha 2HS may participate in the regulation of bone metabolism in vivo.

Glycosaminoglycan content in neonatal rat aortic smooth muscle cell cultures

In the present study the biosynthesis of glycosaminoglycans (GAGs) by neonatal rat aortic smooth muscle cells in culture was studied. Heparan sulfate (HS) was the predominant GAG of the cell layer accounting for 32-49% of the total GAGs depending on the time in culture. The presence of low sulfated chondroitin sulfate (LSC) in aortic smooth muscle cell cultures is reported here for the first time. The effect of ascorbate on the synthesis and accumulation of these macromolecules resulted in a relative increase of C4S and DS in the cell layer. In contrast, the distribution of the GAGs which were secreted into the medium was not significantly effected by the addition of ascorbate. While HS was always found to be a minor component, the other GAGs were present in about equal concentrations. The total GAG accumulation in the medium was much greater (91-97%) than that of the cell layer (3-9%) indicating that the cells are synthesizing relatively large amounts of GAGs, although incorporation of these macromolecules into the extracellular matrix was consistently low.

Cholinergic effects on spike-density and burst-duration of medullary respiration-related neurones in the rabbit: an iontophoretic study

Cholinoceptive properties of 180 medullary respiration-related neurones (RRN) were studied in urethane-anaesthetized rabbits. Acetylcholine (ACh) and agonists, as well as antagonists of muscarinic receptors and nicotinic receptors, were administered iontophoretically. Respiration-related neurons were classified with respect to the correlation of their activity with the activity of the phrenic nerve: phase-bound inspiratory (I) and expiratory (E) neurones and phase-spanning expiratory-inspiratory and inspiratory-expiratory neurones were discriminated. Acetylcholine altered the activity of 170 respiration-related neurones. In 49 cells the discharge-rate (f) alone was affected. In 44 respiration-related neurones the burst-duration (tbd) only was altered. In 77 respiration-related neurones the discharge rate and burst duration were affected simultaneously. Inhibitory actions of ACh prevailed over excitatory actions on inspiratory neurones. In expiratory neurones the discharge rate was increased or decreased in about the same number of cases. In most phase-spanning neurones the discharge rate was increased. Cholinergic inhibition of burst duration was observed in most respiration-related neurones. In all phase-types of respiration-related neurones muscarinic as well as nicotinic actions of ACh were demonstrated. In inspiratory and expiratory-inspiratory neurones muscarinic effects on the discharge rate prevailed over nicotinic effects. More nicotinic than muscarinic effects on discharge rate were observed in expiratory and inspiratory-expiratory neurones. Cholinergic effects on burst duration in about the same number of respiration-related neurones were mediated by muscarinic or by nicotinic receptors, respectively. Various types of cholinoceptors may be involved in these effects. The results suggest that cholinergic mechanisms play an important role in the control of the central regulation of respiratory movements. The functional significance of cholinergic effects on respiration-related neurones is discussed with special emphasis of effects on burst duration.

Three forms of BRP-2 (bone resorptive proteins) from human cancer ascites fluid and their relationship to human serum alpha-2 HS-glycoprotein

Two new forms of BRP-2, a previously described bone resorptive protein, were purified from ascites fluids obtained from patients with hypercalcemia and metastatic bone cancer. The apparent molecular weights of BRP-2 and of these two proteins were 52,000, 48,000, and 46,000, respectively, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The three proteins have essentially the same amino acid compositions but differ with respect to their carbohydrate moieties. The amino-terminal amino acid sequences of the three glycoproteins were identical to each other as well as to human serum alpha 2HS-(human serum) glycoprotein. The relationship of the three forms of BRP-2 to alpha 2HS was also established immunochemically. The ascites proteins, as well as alpha 2HS, on a molar basis, were approximately one-tenth as potent as bovine parathyroid hormone fragment (1-34) in their abilities to stimulate calcium release from bone in vitro. This study describes for the first time a possible function for human serum alpha 2HS.

Induction of microsomal enzymes in rat liver by oxcarbazepine, 10,11-dihydro-10-hydroxy-carbamazepine and carbamazepine

1. The effects of the new anti-epileptic drug, oxcarbazepine, its major metabolite in man, 10,11-dihydro-10-hydroxy-carbamazepine, and carbamazepine, on hepatic microsomal enzyme activities have been studied in rats after repeated administration of equimolar doses. 2. All three compounds caused a qualitatively similar induction of the mono-oxygenase system, the greatest increase being observed in the activity of 4-nitroanisole O-demethylase. Oxcarbazepine is as potent as carbamazepine, while 10,11-dihydro-10-hydroxy-carbamazepine is a weak inducer. 3. The observation that oxcarbazepine is a potent inducer in rats but not in man is explained by the species differences in its metabolism.

Ultrastructure, carbohydrate, and amino acid analysis of two preparations of the cercarial glycocalyx of Schistosoma mansoni

This study determined the amino acid and carbohydrate composition of 2 cercarial glycocalyx preparations obtained after phenol-water extraction and subsequent gel chromatography. Labeled cercariae were subjected to 85% phenol, thereby dissociating the glycocalyx into the aqueous phase, which was dialyzed and chromatographed on Sepharose CL-2B or -4B in either 4 M guanidine hydrochloride (GuHCl) or 0.1% sodium dodecyl sulfate (SDS). The label eluted primarily in the void volume and was antigenic as tested with rabbit polyclonal antibodies by immunoblotting. Approximately 6 micrograms of protein and 28 micrograms of carbohydrate were obtained from 10(5) cercariae in the antigenic void volume fraction after SDS chromatography. Threonine, serine, and glutamic acid comprised 44% of the amino acid residues of the protein. The predominant sugar was fucose. Galactosamine, glucosamine, galactose, and mannose were also detected. After GuHCl chromatography, free amino acids, predominantly glycine and serine, comprised 17% of the total protein. The carbohydrate composition was similar to that of SDS-chromatographed extracts. Phenol-water extracts eluting in the void volume of Sepharose CL-2B were compared by negative staining and scanning electron microscopy with material obtained from medium in which cercariae shed glycocalyx during transformation to schistosomula. Both the isolated material and the transformation medium contained particles 20-50 nm in diameter, with subunits of 15-20 nm. These studies show that the cercarial glycocalyx is particulate, contains mainly carbohydrate and some protein, and is solubilized by phenol-water extraction.

Beta-microseminoprotein (beta-MSP) is not an inhibin

Beta-microseminoprotein (beta-MSP), a sperm-coating antigen isolated from human seminal plasma, has apparent structural identity with "beta-inhibin" isolated from the same source. Publication of the amino acid sequence of beta-MSP revealed a greater than 96% homology with "beta-inhibin," with only a proline-threonine substitution at positions 39 and 40, and the omission of a glycine at position 93. Due to the nearly identical sequences of "beta-inhibin" and beta-MSP, we examined the ability of beta-MSP and its tryptic peptides to inhibit basal follicle-stimulating hormone (FSH) secretion from rat pituitary cells in culture, the inhibin bioassay. Whole pituitaries collected from 250- to 300-g male rats were dispersed enzymatically and plated onto 24-well culture dishes for 3 days. beta-MSP and its tryptic peptides were dissolved in cell culture medium, applied to the pituitary monolayer cell cultures, and incubated for an additional 3 days. FSH levels in the medium were determined by radioimmunoassay. A partially purified preparation of inhibin and our in-house inhibin standard, both prepared from porcine follicular fluid (pFFl), were included in the same assay. Whereas the partially purified inhibin from pFFl showed a dose-dependent inhibition of FSH secretion, with a 50% inhibitory dose (ID50) of 50 ng, which paralleled that of the standard, beta-MSP and its tryptic peptides failed to depress FSH levels in the medium at any of the doses tested (10-10,000 ng/ml). We conclude that beta-MSP is not an inhibin under our assay conditions.

A stepper motor-driven microelectrode positioner

The mechanical elements and the electronic control system from a stepper motor-driven microelectrode positioner is described. The unit embodies a high-precision small step angle hybrid motor. The compact, rugged and totally concentric design of the mechanic, by a spindle mechanism achieves the necessary precision by translating the stepwise rotations of the motor into steps of linear movement. The system takes advantage of commercially available low friction parts such as ball bearings, ball bushings and axles with hardened surfaces. The related electronic control unit is designed around the most recent integrated circuitry which is both sophisticated and economical. Though the described system is designed to be built in an average departmental workshop it compares favorably with more expensive commercial units and in some aspects outperforms them.

Metabolism of hydralazine in man. Part II: Investigation of features relevant to drug safety

The metabolism of hydralazine (1-hydrazinophthalazine hydrochloride, Apresoline) was investigated in 17 hypertensive patients of known acetylator status who were chronically treated with oral doses of 50 mg b.i.d. or 100 mg b.i.d. hydralazine. The acetylator status was assessed either by the monoacetyldapsone/dapsone ratio or by the isoniazide plasma half-life. In each patient the tests were performed on two different days of treatment and they included the analyses of four hydralazine metabolites (NAc-HPZ, 3OH-MTP, MTP and TP), as well as apparent hydrazine in urine and also the determination of plasma concentrations of apparent hydralazine. All data of the two experiments performed within an interval of at least five days were in good agreement, thus indicating that the patients were in pharmacokinetic steady states. No correlation was detectable between any of the determined amounts of metabolites of hydralazine and the assigned acetylator status of the patients. On the other hand the rank order of the urinary yields of the two main metabolites NAc-HPZ and 3OH-MTP suggest to be a representative scale for the patients' status in respect to the biotransformation of the drug itself. The urinary yield of apparent hydrazine is dependent on the pH applied during the analyses and is not correlated with any of the other data recorded. The findings of the present study support the assumption that measuring a relevant prominent metabolite of the drug itself may lead to a more reliable assessment of the particular metabolic status of the patients than by classification through a non treatment related foreign compound.(ABSTRACT TRUNCATED AT 250 WORDS)