Behavioral effects of vigabatrin correlated with whole brain gamma-aminobutyric acid metabolism in audiogenic sensitive rats

The present study evaluates dose-dependent behavioral effects of acutely or subacutely administered single doses of vigabatrin (gamma-vinyl gamma-aminobutyric acid, gamma-vinyl GABA, CAS 60643-86-9) in audiogenic sensitive rats, in correlation with whole brain GABA metabolism. There was a discrepancy in timing between behaviorally observed maximal antiepileptic protection (4 h after i.p. administration of gamma-vinyl GABA) and on the other hand maximal inhibition of GABA-transaminase activity and maximal increase of whole brain GABA content (24 h after i.p. administration of gamma-vinyl GABA). This suggests that the antiepileptic properties of gamma-vinyl GABA not only depend on GABA-ergic neurotransmission. A possible explanation is a gamma-vinyl GABA-induced decrease of excitatory amino acids or increased glycine concentrations in the brain.     

Investigation and evaluation of zinc protoporphyrin as a diagnostic indicator in lead intoxication

To evaluate the utility of zinc protoporphyrin (ZPP) as an indicator of lead exposure, we examined 128 workers employed at a battery storage plant and two smelters, 343 persons who lived within 200 m of the plants, and 217 controls. Based on Chinese criteria, the "normal" ZPP value among inhabitants of Shaanxi Province was determined to be 85 micrograms/100 ml. ZPP proved to be a more sensitive and specific indicator of lead exposure, at both high and lower levels, than PbB or PbU. Among 115 patients who underwent chelation therapy for lead poisoning, ZPP also proved to be a valid index of recovery.     

Biotinylation in vivo as a sensitive indicator of protein secretion and membrane protein insertion

Escherichia coli biotin ligase is a cytoplasmic protein which specifically biotinylates the biotin-accepting domains from a variety of organisms. This in vivo biotinylation can be used as a sensitive signal to study protein secretion and membrane protein insertion. When the biotin-accepting domain from the 1.3S subunit of Propionibacterium shermanii transcarboxylase (PSBT) is translationally fused to the periplasmic proteins alkaline phosphatase and maltose-binding protein, there is little or no biotinylation of PSBT in wild-type E. coli. Inhibition of SecA with sodium azide and mutations in SecB, SecD, and SecF, all of which slow down protein secretion, result in biotinylation of PSBT. When PSBT is fused to the E. coli inner membrane protein MalF, it acts as a topological marker: fusions to cytoplasmic domains of MalF are biotinylated, and fusions to periplasmic domains are generally not biotinylated. If SecA is inhibited by sodium azide or if the SecE in the cell is depleted, then the insertion of the MalF second periplasmic domain is slowed down enough that PSBT fusions in this part of the protein become biotinylated. Compared with other protein fusions that have been used to study protein translocation, PSBT fusions have the advantage that they can be used to study the rate of the insertion process.     

Mutagenic and antimutagenic activities of human whole blood, plasma and albumin

The seeds of Crepis capillaris were used to examine the mutagenic und antimutagenic properties of human whole blood, plasma, serum albumin and gamma-globulin by recording chromosomal and chromatid aberrations. The antimutagenic activity was determined by preliminary, simultaneous, and subsequent biosubstrate treatments of the seeds. The whole and twice-diluted blood, as well as plasma, induced aberrations exceeding the level of self-arbitrary mutagenesis by 3.7-5.3 and 2.6-3.1 times, respectively. When the blood was diluted to its 20% concentration, the antimutagenic efficiency of biological fluids was recorded. Human serum albumin and gamma-globulin were found to have an antimutagenic effect. In the dilutions having no antimutagenic effect, blood, plasma, and albumin showed their ability to be effectively decrease the level of induced aberrations.     

Comparison of 5-fluorouracil pharmacokinetics in whole blood, plasma, and red blood cells in patients with colorectal cancer

STUDY OBJECTIVE: To compare 5-fluorouracil (5-FU) pharmacokinetics in whole blood, plasma, and red blood cells in patients with colorectal cancer. DESIGN: Prospective, unblinded observational study in consecutive patients. SETTING: Large regional teaching hospital. PATIENTS: Five patients with colorectal cancer. INTERVENTIONS: Patients received folinic acid 200 mg/m2 intravenously over 2 hours, followed by 5-FU 600 mg/m2 intravenous bolus over 30 minutes, then 5-FU 600 mg/m2 intravenous infusion over 22 hours, administered on days 1 and 2. This 48-hour cycle was repeated every 14 days. MEASUREMENTS AND MAIN RESULTS: Concentrations of 5-FU in whole blood, plasma, and red blood cells were determined by high-performance liquid chromatography. ADAPT II was used for pharmacokinetic computations. The optimum model was determined for each matrix by calculating Akaike's information criteria values. Concentrations of 5-FU in whole blood were 106-115% of simultaneous plasma concentrations (median 112%), and packed red blood cell levels were 5-17% of plasma concentrations (median 11%). The drug's concentration-time profile was similar in the three matrices. The drug is reported to be unstable in whole blood, and red blood cell 5-FU concentrations were near the limit of detection (10 ng/ml), supporting plasma as the preferred matrix for therapeutic drug monitoring studies. Six pharmacokinetic models were fitted to the 5-FU individual data sets to determine the best curve fit. The optimal model for whole blood and plasma data sets was one compartment with both linear and nonlinear elimination models; a one-compartment model with nonlinear elimination provided the best curve fit for 5-FU in red blood cells. A two-compartment model with nonlinear elimination gave a similar degree of curve fit for plasma 5-FU as the one-compartment model with both linear and nonlinear elimination. CONCLUSIONS: These pharmacokinetic results provide the basis for further investigation into the ability to correlate 5-FU systemic exposure with clinical drug activity.     

Lead in inner-city soil and its possible contribution to children''s blood lead

The heterologous expression of a cloned endoglucanase gene (endA) from the ruminal bacterium Ruminococcus flavefaciens 17 was demonstrated in the Streptococcus species S. bovis JB1 and S. sanguis DL1. The endA gene was introduced into S. bovis and S. sanguis using the Escherichia coli/Streptococcus shuttle vector pVA838. Expression of the gene was detected by clearing zones around the recombinant colonies on agar plates containing carboxymethylcellulose stained with Congo red. S. bovis JB1 containing the endA gene was capable of utilizing cellotetraose at a faster rate than the parent strain. This is the first demonstration that Streptococcus species can express a gene from a Ruminococcus flavefaciens strain.     

The influence of bone and blood lead on plasma lead levels in environmentally exposed adults

There is concern that previously accumulated bone lead stores may constitute an internal source of exposure, particularly during periods of increased bone mineral loss (e.g., pregnancy, lactation, and menopause). Furthermore, the contribution of lead mobilized from bone to plasma may not be adequately reflected by whole-blood lead levels. This possibility is especially alarming because plasma is the main circulatory compartment of lead that is available to cross cell membranes and deposit in soft tissues. We studied 26 residents of Mexico City who had no history of occupational lead exposure. Two samples of venous blood were collected from each individual. One sample was analyzed by inductively coupled plasma-magnetic sector mass spectrometry for whole-blood lead levels. The other sample was centrifuged to separate plasma, which was then isolated and analyzed for lead content by the same analytical technique. Bone lead levels in the tibia and patella were determined with a spot-source 109Cd K-X-ray fluorescence instrument. Mean lead concentrations were 0.54 microg/l in plasma, 119 microg/l in whole blood, and 23.27 and 11.71 microg/g bone mineral in the patella and tibia, respectively. The plasma-to-whole-blood lead concentration ratios ranged from 0.27% to 0.70%. Whole-blood lead level was highly correlated with plasma lead level and accounted for 95% of the variability of plasma lead concentrations. Patella and tibia lead levels were also highly correlated with plasma lead levels. The bivariate regression coefficients of patella and tibia on plasma lead were 0.034 (p<0. 001) and 0.053 (p<0.001), respectively. In a multivariate regression model of plasma lead levels that included whole-blood lead, patella lead level remained an independent predictor of plasma lead level (ss = 0.007, p<0.001). Our data suggest that although whole-blood lead levels are highly correlated with plasma lead levels, lead levels in bone (particularly trabecular bone) exert an additional independent influence on plasma lead levels. It will be important to determine whether the degree of this influence increases during times of heightened bone turnover (e.g., pregnancy and lactation).     

Subclinical vestibulo-cerebellar, anterior cerebellar lobe and spinocerebellar effects in lead workers in relation to concurrent and past exposure

By computerized static posturography, the subclinical effects of past and concurrent lead absorption on the vestibulo-cerebellum (lower vermis), anterior cerebellar lobe and spinocerebellar afferent pathway were examined in 49 male chemical factory workers exposed to lead stearate (lead workers). Their concurrent blood lead (BPb) concentrations ranged from 7 to 36 (mean 18.0) microgram/100 g. In the past, their maximum BPb ranged from 11 to 113 (mean 47.7) micrograms/100 g; mean BPb was 7-52 (mean 23.5) micrograms/100 g; and cumulative BPb, defined as mean BPb x years of exposure, was 15-1268 (mean 390.6) micrograms.year/100 g. Control subjects were 23 healthy male workers who had never been occupationally exposed to lead. The postural sway of high (2-4 Hz) and low (1 Hz or less) frequencies with eyes open for lead workers was significantly greater than that for controls in the medio-lateral (right-left) and anterior-posterior directions. Similarly, the sway of high and low frequencies with eyes closed was significantly larger in lead workers than in controls in the medio-lateral direction. Results of stepwise multiple regression analysis indicated that the sway with frequencies of 0.5-2 Hz with eyes open was related to concurrent BPb in the anterior-posterior direction. With eyes closed the sway of high frequency was significantly related to mean BPb in the past in the medio-lateral direction. The pattern of the changes suggests that the vestibulo-cerebellum, anterior cerebellar lobe and spinocerebellar pathway are asymptomatically affected by lead. It appears that the change in the vestibulo-cerebellum reflects concurrent lead absorption, while on the other hand, that in the anterior cerebellar lobe reflects past lead absorption.     

Twenty-four-hour rhythms of plasma catecholamines and their relation to cardiovascular parameters in healthy young men

Diurnal and ultradian rhythms of plasma norepinephrine and epinephrine and their role in the regulation of cardiovascular parameters were investigated over 24 h of recumbency in a group of five men. Catecholamines were measured at 10 min intervals, and blood pressure and heart rate were recorded continuously. Norepinephrine and epinephrine rapidly fluctuated in each subject, with no obvious diurnal rhythm. Spectral analysis suggested two ultradian rhythms with periods of around 12 h and 50-100 min for both catecholamines. The pulse detection programs PULSAR and CLUSTER revealed 20-30 pulses/24 h for norepinephrine and epinephrine, with a significant correlation between the two rhythms (r = 0.63-0.80, P < 0.001). Neither the frequency nor the amplitude of these rapid fluctuations differed between day and night. Arousal in the morning caused a small increase in plasma catecholamines and getting out of bed a large increase. Thus changes in posture and activity are the main influences on the diurnal variations of plasma catecholamines reported previously, while the ultradian rhythms of sympathoadrenomedullary activity appear to be of intrinsic origin. Blood pressure and heart rate exhibited a diurnal rhythm with a nightly decrease. Arousal and rising from bed increased blood pressure and heart rate significantly. Although the amplitude of the rapid fluctuations of plasma catecholamines at times exceeded those caused by postural changes in the morning, when both plasma norepinephrine and epinephrine levels correlated highly with all cardiovascular parameters, correlations were not significant during recumbency. Thus the intrinsic ultradian fluctuations of plasma catecholamines appear not to be involved in the control of cardiovascular parameters during recumbency, and the increase in blood pressure and heart rate in the morning appears to be controlled by direct sympathetic neural input to the heart and vasculature in response to changes in activity and posture rather than by an endogenous surge of plasma catecholamines.     

Daily variations of platelet aggregation in relation to blood and plasma serotonin in diabetes

INTRODUCTION: An increase in digitalis-like substances has been reported in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. We hypothesized that the role of saline and unilateral nephrectomy in DOCA hypertension may be due to stimulation of endogenous digitalis-like substances. METHODS: We investigated the effects of digoxin and DOCA alone and in combination in intact rats drinking water. Forty male Sprague-Dawley rats were used (body weight 223-298 g). RESULTS: Neither digoxin (40 micrograms/kg per day, by gavage, for 35 days, n = 10) nor DOCA (30 mg/kg twice a week, subcutaneously, for 5 weeks, n = 10) caused a consistent increase in blood pressure in intact rats drinking water. In contrast, combined digoxin and DOCA administration (n = 10) increased systolic blood pressure from day 18 of treatment onwards, to a maximum at day 34 compared with sham-treated rats (n = 10). There were no consistent changes in water intake, urine volume, urinary sodium or potassium excretion, or plasma sodium or potassium concentration with digoxin treatment. DOCA increased water intake and urine volume, and caused an initial decrease in urinary sodium excretion, but no change in urinary potassium excretion or plasma sodium concentration. Plasma potassium excretion was lower in DOCA- than sham-treated rats. CONCLUSION: Combined digoxin and DOCA administration in intact rats drinking water increased blood pressure significantly compared with either drug alone, raising the possibility that the mechanism by which nephrectomy and salt loading contribute to DOCA hypertension in the rat might be through stimulation of endogenous digitalis-like substances.     

Contents of D-lactate and its related metabolites as well as enzyme activities in the liver, muscle and blood plasma of aging rats

Regulatory elements within the promoter of the pollen-specific NTP303 gene from tobacco were analysed by transient and stable expression analyses. Analysis of precisely targeted mutations showed that the NTP303 promoter is not regulated by any of the previously described pollen-specific cis-regulatory elements. However, two adjacent regions from -103 to -86 bp and from -86 to -59 bp were shown to contain sequences which positively regulated the NTP303 promoter. Both of these regions were capable of driving pollen-specific expression from a heterologous promoter, independent of orientation and in an additive manner. The boundaries of the minimal, functional NTP303 promoter were determined to lie within the region -86 to -51 bp. The sequence AAATGA localized from -94 to -89 bp was identified as a novel cis-acting element, of which the TGA triplet was shown to comprise an active part. This element was shown to be completely conserved in the similarly regulated promoter of the Bp 10 gene from Brassica napus encoding a homologue of the NTP303 gene.