Is 3,4-dihydroxyphenylglycol the major route of central norepinephrine metabolism in rat brain?

Central norepinephrine (NE) metabolism was assessed by measuring 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) and 3,4-dihydroxyphenylethyleneglycol (DHPG) in different rat brain areas after saline or probenecid (300 mg/kg) administration. Under probenecid, results showed an increased accumulation of total MHPG and DHPG, and a clear preponderance of DHPG levels over MHPG in almost all the brain areas examined. Estimation of their formation rates confirmed that in basal conditions DHPG is formed more rapidly. This study supports the notion that, without ruling out the importance of MHPG, brain DHPG may be a useful index of central NE activity.     

Measurement of plasma D-dimer for diagnosis of deep venous thrombosis

Venography was performed on fifty-six patients suspected of having deep venous thrombosis (DVT) of the legs. The accuracy of the D-dimer measurement in plasma using two latex tests and an enzyme-linked immunosorbent assay (ELISA) was compared with that of usual determination of total fibrin(ogen) degradation products (FDPs) in serum with respect to the presence of DVT. The three D-dimer tests were clearly superior to the FDP assay, but only the ELISA could accurately rule out the diagnosis of DVT with a predictive value of 100% when plasma D-dimer level was less than 200 micrograms/L. However, this test cannot be used for positive diagnosis (false positive rate of 69%). Thus, plasma D-dimer measurement with ELISA allows identification of patients in whom further investigation by means of more specific tests (venography or plethysmography) is indicated in order to establish the diagnosis of DVT. In contrast to this, sensitivity of the two latex tests studied was low (60 and 76%, respectively), which makes them unsuitable for emergency screening. In addition, the potential of D-dimer dosage for diagnosis of DVT in hospitalized patients is hampered by the presence of associated conditions that are responsible for elevated plasma levels in most cases.     

Quantification of 3,4-methylenedioxymetamphetamine and its metabolites in plasma and urine by gas chromatography with nitrogen-phosphorus detection

A gas chromatographic method with nitrogen-phosphorus detection involving a solid-liquid extraction phase was developed and validated for the simultaneous quantification of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) in plasma. A modification of this method was validated for the analysis of MDMA, MDA, 4-hydroxy-3-methoxymethamphetamine (HMMA) and, 4-hydroxy-3-methoxyamphetamine (HMA) in urine. Under the analytical conditions described, the limits of detection in plasma and urine were less than 1.6 microg/l and 47 microg/l, respectively, for all the compounds studied. Good linearity was observed in the concentration range evaluated in plasma (5-400 microg/l) and urine (100-2000 microg/l) for all compounds tested. The recoveries obtained from plasma were 85.1% and 91.6% for MDMA and MDA, respectively. Urine recoveries were higher than 90% for MDMA and MDA, 74% for HMMA, and 64% for HMA. Methods have been successfully used in the assessment of plasma and urine concentrations of MDMA and its main metabolites in samples from clinical studies in healthy volunteers.     

Measurement of tele-methylhistamine and histamine in human cerebrospinal fluid,urine, and plasma

A gas chromatographic-mass spectrometric method described by us to measure tele-methylhistamine (t-MH) in brain was used to measure t-MH in human cerebrospinal fluid (CSF), urine and plasma. The presence of t-MH in these body fluids was rigorously established. No pros-methylhistamine could be detected, and it was used as internal standard to quantify t-MH in the fluids. The mean levels of t-MH were: urine, 943 pmol/mg creatinine; plasma, 12.3 pmol/ml; and CSF, 2.2 pmol/ml. Parallel measurements of histamine by a radioenzymatic method showed, respectively, 182 pmol/mg creatinine; 19.5 pmol/ml; and 388 pmol/ml. The levels of HA in CSF, much higher than those of its metabolite, t-MH, are high enough to stimulate HA receptors in the central nervous system.     

Biochemical diagnosis of pheochromocytoma and neuroblastomas

Pheochromocytoma and neuroblastoma are distinct tumours, but their biological diagnosis is based on secretion increase of one or several catecholamines. Assays have to be very sensible and specific for an early diagnosis. 24 hours urinary catecholamines and metabolites are currently measured, but technical improvements permit plasma metanephrine assay, an excellent indicator of pheochromocytoma. HPLC coupled to electrochemical detection represents the most efficient methodology. After a review of urinary and plasma assay methods, the authors show usual values of catecholamines, metanephrines, HVA and VMA, according to ages, and give examples of results encountered in classical or not tumours and in falsely positive cases. Urinary metanephrine assay is the most sensible and specific in biological diagnosis of pheochromocytoma, while catecholamines and VMA assays lack of sensibility. Results have to be given by 24 hours and by creatinine ratio. Metanephrine assay can be performed also in plasma and exhibits the same interest. However, in urine as in plasma, in case of renal failure, results cannot be interpreted. Neuroblastoma biological diagnosis is based classically on HVA, VMA, and dopamine assays, nowadays only in 24 hours urine (or in urinary micturition for screening), and results are also expressed as creatinine ratio. But even if several assays are advisable, 5% of the neuroblastoma cases do not produce increased catecholamine values. In some cases, metanephrine assay could be of interest. After the age of 12 months, clinical expression of neuroblastoma is dramatic in 70% of cases. So, a biological screening has been experimented in several countries including France. A French translation of the consensus conference report (1998) is appended, which shows the complexity of neuroblastoma screening. Now, there is no evidence that early tumour detection by screening lessens the mortality rate, but a weak benefit is not excluded.     

Comparison of free plasma metanephrines enzyme immunoassay with 131I-MIBG scan in diagnosis of pheochromocytoma

Measurement of free plasma metanephrines (metanephrine and normetanephrine), usually performed by high-performance liquid chromatography with electrochemical detection (HPLC-ECD), has been recommended as the single biochemical test of choice for the diagnosis of pheochromocytoma. Alternatively, a widely available, simple means to measure these biomarkers with enzyme immunoassay (EIA) needs to be studied. The aim of this study was to investigate the diagnostic efficacy of such a method in comparison with (131)I-metaiodobenzylguanidine (MIBG) whole body scan (WBS) in patients with pheochromocytoma. We enrolled patients undergoing (131)I-MIBG WBS due to clinical findings suggestive of pheochromocytoma (n = 45), and patients with primary hypertension (n = 36). All subjects had blood tests for free plasma metanephrine (MN) and normetanephrine (NM) with a commercially available EIA kit. WBS was positive in 30 pheochromocytoma patients and negative in 15 refuted ones, with 100% accuracy. The sensitivity, specificity and accuracy of MN and NM in combination (either or both positive) were 96.7%, 86.3% and 90.1%, showing comparable diagnostic performance both to (131)I-MIBG WBS (all p > 0.1), and also to the same markers measured with HPLC-ECD reported in the literature. These results showed that the EIA method may be eligible as an alternative to HPLC-ECD for plasma metanephrine determination in the identification of pheochromocytoma.     

Evaluation of the clonidine-suppression test in the diagnosis of pheochromocytoma

Summary In this study we examined the preoperative value of the clonidine-suppression test in 15 patients with surgically proved pheochromocytomas. The result of the clonidine-suppression test was pathological (epinephrine plus norepinephrine above 500 ng/l 3 h after clonidine) in 10 of 15 patients (66%). These patients had relatively large tumors and higher basal norepinephrine plasma levels. Out of the 5 cases without a pathological clonidine test 4 had normal basal plasma catecholamine levels with the result that the clonidine test could not be properly applied and 1 case produced a false negative result. These 5 cases generally had smaller tumors and lower plasma catecholamine levels. Two of these cases had basally raised epinephrine values. The other three cases had either a paradoxical increase or a suspiciously low fall (less than 25%) in norepinephrine within the normal range. We conclude that the clonidine-suppression test is only reliable for the diagnosis of relatively large pheochromocytomas.Abbreviations MIBG metaiodobenzylguanidine - HPLC High-performance liquid chromatography     

Use of formaldehyde-induced fluorescence for cytological diagnosis of pheochromocytoma

Eleven cases with pheochromocytoma were cytologically investigated on touch preparations using formaldehyde-induced fluorescence method (FIF) in addition to the usual Papanicolaou's stain (PAP) and May-Grünwald Giemsa stain (MGG). The specific catecholamine fluorescence was successfully observed in the cytoplasm of tumor cells and also in the background. Application of FIF for touch preparation is simple in technique and may greatly contribute for confirmation of the diagnosis of pheochromocytoma. MGG stained the cytoplasm composed of two-tone colors: eosinophilic granular in the perikarya and basophilic granular around nucleus. Electronmicroscopically, they were consistent with catecholamine granules and abundant rough endoplasmic reticulums, respectively. Although, it is fairly difficult to determine whether tumor cells are other malignant tumors or not by using PAP, small N/C ratio might be a useful index for pheochromocytoma. Combination of FIF, MGG, and PAP makes it easy to confirm the diagnosis of pheochromocytoma.     

Measurement ofN τ-methylhistamine concentrations in plasma and urine as a parameter for histamine release during anaphylactoid reactions

N -methylhistamine concentrations in plasma and urine were determined using a newly developed simultaneous determination for histamine andN -methylhistamine, based on isotope dilution mass fragmentography. Three groups of patients were investigated: patients receiving intravenously-administered iodamide for excretory urography, patients receiving a wasp-sting challenge, and patients treated with an intravenously-administered muscle relaxant. In all patients showing a distinct systemic anaphylactic or anaphylactoid reaction histamine andN -methylhistamine concentrations were found to be elevated. From the results of this study it can be concluded thatN -methylhistamine in plasma and urine is a good parameter for histamine release, and that the determination of this histamine metabolite are less hampered by possible artefacts (due to basophil disrupture, a very short half-life time or bacterial production) than determinations of histamine itself.     

Treatment of pheochromocytoma: changes in diagnosis and therapy

Evident progress has been made in the treatment of pheochromocytoma. The results of hormone analysis became very accurate, the method for tumor localisation are non invasive and safe: with 131-I-MIBG, ultrasonography and CT-scan an exact preoperative localisation is possible without serious risks. Patients are prepared for the operation with alpha- and beta-blocking agents. Modern methods of anaesthesia with continuous monitoring of blood pressure, pulmonary pressure and cardiac output and a standardized operative procedure are essential. From 1965 to 1987 71 patients with a total of 87 catecholamine producing tumors have been operated. In all cases a transabdominal access was chosen. Biadrenal tumors were removed in 8 patients, multiple (7) tumors in 2 patients. The comparison of the 2 time intervals 1965 to 1976 and 1977 to 1987 showed a significant decrease of serious intra- and postoperative complications. Surgical specimens of 36 patients with pheochromocytoma were used for immunohistologic evaluation. Marked positivity was found in 44% of cases for calcitonin. The reaction for vasoactive intestinal polypeptide (VIP) was positive in 28% of cases. Somatostatin was not detected in any case, neuron-specific enolase (NSE) in all cases. 6 patients with malignant pheochromocytoma were treated with high doses of 131-I-MIBG, 4 other patients received a combined chemotherapy.     

Measurement of the novel decapeptide cetrorelix in human plasma and urine by liquid chromatography-electrospray ionization mass spectrometry.

A sensitive LC-MS quantitation method of cetrorelix, a novel gonadotropin releasing hormone (GnRH) antagonist, was developed. Plasma and urine samples to which brominated cetrorelix was added as an internal standard (I.S.) were purified by solid-phase extraction with C8 cartridges. The chromatographic separation was achieved on a C18 reversed-phase column using acetonitrile-water-trifluoroacetic acid (35:65:0.1, v/v/v) as mobile phase. The mass spectrometric analysis was performed by electrospray ionization mode with negative ion detection, and the adduct ions of cetrorelix and I.S. with trifluoroacetic acid were monitored in extremely high mass region of m/z 1543 and 1700, respectively. The lower limit of quantitation was 1.00 ng per 1 ml of plasma and 2.09 ng per 2 ml of urine, and the present method was applied to the analysis of pharmacokinetics of cetrorelix in human during phase 1 clinical trial.     

肾上腺嗜铬细胞瘤的多层螺旋CT诊断

目的探讨肾上腺嗜铬细胞瘤的多层螺旋CT表现,提高CT诊断准确性。方法24例经手术后病理学诊断证实的肾上腺嗜铬细胞瘤患者,其中男性12例,女性12例;年龄13～75岁,平均年龄47．24岁。回顾性分析这些患者的16层螺旋CT影像资料。结果24例共25个肿块（23例为单侧,1例为双侧）,左侧10个,右侧15个。CT平扫显示肿块直径大于3cm的20个（83．3％）,肿块伴有钙化4个,伴有囊变11个,肿块密度不均匀14个,密度均匀11个,境界清楚。增强后均呈明显强化,其中肿块双期均呈不均匀强化17个,双期均呈均匀强化4个,动脉期不均匀强化而实质期较均匀强化4个．增强后最高CT值大于80Hu21个（87．5％）。所有病例均伴有血儿茶酚胺增高。结论肾上腺区较大肿块伴明显不均匀强化,结合临床资料,可提示嗜铬细胞瘤的诊断。     

Recall performance, plasma cortisol and plasma norepinephrine in normal human subjects

This study investigated hypothalamic-pituitary-adrenal (HPA)-axis and sympathetic nervous system (SNS) correlates of recall performance in normal human subjects. Twenty-two normal human subjects were given one memory task: short-term recall of unrelated non-organizable lists of neutral words, in immediate recall conditions. Two types of memory were individualized: measures reflecting effortful processing and measures reflecting automatic processing, which were related to 3 daytime plasma cortisol (CORT) and plasma NE values, and assessed after venipuncture. It was hypothesized that plasma CORT is positively related and plasma norepinephrine (NE) is negatively related to effortful processing. Pearson correlation was computed and regression analysis was performed. Positive correlation appeared between plasma CORT values and negative correlation appeared between plasma NE values and measures reflecting effortful processing. However, stepwise multiple regression analysis showed that only morning plasma CORT values are functionally positively and afternoon plasma NE values are functionally negatively related to effortful processing. This suggests that morning HPA-axis activities enhance and afternoon SNS activities inhibit effortful processing.     

Effect of a synthetic norepinephrine precursor, L-threo-3,4- dihydroxyphenylserine on the total norepinephrine concentration in the cerebrospinal fluid of parkinsonian patients

We studied the effect of a synthetic norepinephrine precursor, L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS) on the total (conjugated and unconjugated) norepinephrine concentrations in the cerebrospinal fluid (CSF) of 6 parkinsonian patients with freezing phenomenon. The total norepinephrine concentrations in the CSF increased from 5- to 75-fold after treatment with L-threo-DOPS. The degree of increase in the norepinephrine (NE) concentrations was closely correlated to the dosage of L-threo-DOPS. The freezing phenomenon improved in 3 out of 6 patients.     

Measurement of mercury in human urine

Four methods of determining the concentration of mercury in human urine have been studied. A simple method suitable for general laboratory use is recommended and the requirements for accurate results are defined. The method employs mild oxidation with permanganate and HS₂O₄ followed by dithizone extraction and measurement of absorbance at 485 nm and 620 nm.