Prothrombin times and activated partial thromboplastin times in toxicology: a comparison of different blood withdrawal sites for wistar rats

The prothrombin time (PT) and the activated partial thromboplastin time (APTT) for untreated male Wistar rats were determined on the Sysmex CA-5000 Instrument for blood taken from the orbital sinus, tail vein, vena cava and aorta. Boxplot and statistical analysis was performed. Only orbital sinus puncture yields unpredictable and unacceptable variation/prolongation of clotting times.     

Serotonergic projections from the midbrain periaqueductal gray and nucleus raphe dorsalis to the nucleus parafasccicularis of the thalamus

By a double-labeling method combining the retrograde tracing of horseradish peroxidase and the immunocytochemical technique, serotonin-like immunoreactive neurons in the midbrain periaqueductal gray (PAG) and nucleus raphe dorsalis (DR) of the rat were observed to send projection fibers to the nucleus parafascicularis of the thalamus bilaterally with an ipsilateral dominance. These serotonin-containing projecting neurons were observed mainly at the middle-caudal levels of the ventrolateral subdivision of the PAG and less at the middle-rostral levels of the DR.     

Altered enzyme activities of xenobiotic biotransformation in kidneys after subchronic administration of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) to rats

Activities of the xenobiotic metabolizing enzymes were measured in the liver, kidney, duodenum and lung microsomes and cytosol fractions of Wistar rats after subchronic administration of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a potent bacterial mutagen in chlorinated drinking water. MX was administered by gavage at the dose level of 30 mg/kg for 18 weeks (low dose), or at the dose level which was raised gradually from 45 mg/kg for 7 weeks via 60 mg/kg for 2 weeks to a clearly toxic dose of 75 mg/kg for 5 weeks (high dose). Microsomal and cytosolic preparations were made and the activities of 7-ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-dealkylase (PROD), NADPH-cytochrome-c-reductase, UDP-glucuronosyltransferase (UDPGT) and glutathione-S-transferase (GST) were measured. Kidneys were affected most. A dose-dependent decrease was observed in EROD (90% in males, 80% in females at the high dose) and in PROD (58% in females, at the high dose) in kidneys. An increase was, however, detected in kidney NADPH-cytochrome-c-reductase (66% in females at high dose), UDPGT (89% in males and 97% in females at high dose) and GST activities (56% in males and 50% in females at high dose). MX caused only a few changes in the enzyme activities of the liver. The EROD activity was decreased 25% to 37%, both in the livers of males and females, but the total content of P450s was not altered. Hepatic GST activity was elevated in females in a dose-dependent manner (31% and 44%). GST activity was elevated in duodenum in females (59%) at the high dose. There were no marked changes in the enzyme activities in the lungs. MX was a weak inhibitor of EROD activity both in the liver and kidney microsomes in vitro, decreasing the EROD activity by 53% and 43%, respectively at the concentration of 0.9 mM. The results indicate that MX decreases the activity of phase I metabolism enzymes, but induces phase II conjugation enzyme activities, particularly in kidneys in vivo. It is possible that these changes contribute to metabolism of MX in kidneys and renders them susceptible to MX in the course of repeated exposure.     

用Fura-2测定周围血单个核细胞内游离钙浓度

本文用Fura-2测定了周围血单个核细胞内游离钙浓度，并对有关实验条件进行了探讨。对比研究表明，血标本在4℃保存4小时对测定结果无显著影响，测定标本中单个核细胞数以10~5～10~6/ml为宜。认为测定单个核细胞内游离钙浓度对判断单个核细胞的功能状况有一定帮助。     

Distribution of calbindin D-28K and parvalbumin immunoreactivities in the nucleus olfactorius anterior of the rat

The distributions of calbindin D-28K (CaBP) and parvalbumin (PV) in the rat nucleus olfactorius anterior (NOA) were described using monoclonal antibodies and the avidin-biotin-peroxidase method. The NOA showed a high immunoreactivity for CaBP, with a rostrocaudal increase in the positive neurons and fibres. Pars externa (NOAe) was the only subdivision which showed a low CaBP immunostaining. PV-positive elements were less abundant than those CaBP immunostained. The main difference in the distributions for both proteins was observed in the pars medialis which was practically PV negative. PV- and CaBP-stained neurons showed similar morphologies in the subdivisions where they were present. In NOAe, we observed a characteristic PV- and CaBP-positive neuronal type, with an oriented dendritic pattern. Transition areas were clearly observable in both CaBP- and PV-labelled sections.     

Stimulation-induced setting of postural muscle tone in the decerebrate rat

These studies demonstrate the presence of pontomedullary areas in the rat brainstem which, when stimulated electrically, serve to set postural muscle tone in the hindlimbs. Low amplitude stimulation of the dorsal tegmental field (DTF) was found to inhibit postural muscle tone and, in some rats, was found to decrease mean arterial pressure. Low amplitude stimulation of the ventral tegmental field (VTF) was found to increase postural muscle tone and, in all cases tested, was found to increase mean arterial pressure.     

Release of newly synthesized h-dopamine in the striatum: An adaptation of the push-pull cannula method to awake restrained and anesthetized rats

The release of newly synthesized ³H-dopamine (³H-DA) was measured in the rat striatum superfused, through a push-pull cannula, with a physiological medium enriched in ³H-tyrosine. The level of spontaneous ³H-DA release was dependent on the topographical localisation of the cannula in the striatum (anterior parts displayed higher levels than posterior ones) and on the anesthetic state (halothane anesthetized rats demonstrated higher levels than awake ones). Inhibition of DA inactivation processes by local application of benztropine (a DA reuptake inhibitor, 10⁻⁶ M) or by IV administration of pargyline (a MAO inhibitor, 100 mg/kg) enhanced the detectable outflow of ³H-DA from the striatum in both halothane anesthetized and awake rats. Local application of D-amphetamine (10⁻⁵ M) or acetylcholine (5 × 10⁻⁵ M) in the presence of eserine (5 × 10⁻⁵ M) evoked respectively a fivefold and a 30% increase in spontaneous ³H-DA release in halothane anesthetized rats. Inhibition of the firing of dopaminergic neurons by IV injection of gamma-hydroxybutyrate (400 mg/kg) produced a 30% decrease in striatal ³H-DA release. The present results demonstrate that the push-pull cannula method is suitable for the study of DA release in both the anesthetized and the awake rat.     

Spermidine/Spermine N-Acetyltransferase, a New Biochemical Marker for Epithelial Proliferation in Rat Bladder

We examined the activity of spermidine/spermine N ¹-acetyltransferase (SAT), a rate-limiting enzyme of the biodegradation of polyamines, in N -butyl- N -(4–hydroxybutyI)nitrosamine-induced transitional cell carcinoma (TCC) and melamine-induced papillomatosis of rat bladder, and compared the activity to that of ornithine decarboxylase (ODC). Both activities were higher in both lesions than in control rats. The difference between SAT and ODC activities in cancerous tissue and papillomatosis was not significant. Cells stained for proliferating cell nuclear antigen (PCNA) were abundant in papillomatosis. TCC had areas with much PCNA. The results indicated that an elevation of SAT activity occurs in both reversible and irreversible proliferation of bladder epithelium and could be important in bladder carcinogenesis.     

Purification of rabbit, rat and mouse protein C with the use of monoclonal antibody to human protein C, PC01

Ca(++)-dependent monoclonal antibody specific to gamma-carboxyglutamic acid (Gla) domain of protein C was produced. It did not cross-react to the other vitamin K-dependent plasma proteins but to protein C of the other species. Using this monoclonal antibody, PC01, rabbit (170 micrograms), rat (60 micrograms) and mouse (40 micrograms) protein Cs were isolated from 100 ml of their plasma by affinity chromatography. All of these protein Cs were two chain form linked by disulfide bond as well as human protein C and activated by thrombin-thrombomodulin complex. Rat and mouse protein Cs showed similar characters to human protein C. On the other hand rabbit protein C had different M(r) of heavy and light chains and showed lower anticoagulant activity compared with human protein C.     

Post-translational processing of thyrotropin-releasing hormone precursor in rat brain: identification of 3 novel peptides derived from pro TRH

The sequence of rat hypothalamic pro-thyrotropin releasing hormone, deduced by sequencing of cDNA, in addition to 5 TRH progenitor genitor sequences contains leader, trailer and 4 intervening sequences separated by paired basic amino acid sequences. We have developed radioimmunoassays to synthetic peptides corresponding to portions of these cryptic proTRH sequences and have used these assays to identify and partially characterize proTRH peptides, distinct from TRH, in extracts of rat brain. Two of these peptides correspond closely in size to one intervening sequence and the car☐y-terminal sequence of proTRH. Three other peptides correspond to the intact amino-terminal leader sequence and two peptides formed by a further cleavage of the leader sequence at an internal paired basic amino acid sequence.