The expression of transthyretin mRNA in the developing rat brain

Specific cDNA and oligonucleotide probes were used to study the appearance of transthyretin mRNA in developing rat brain using Northern gel analysis, cytoplasmic dot hybridization, and in situ hybridization. Transthyretin mRNA in embryonic rat brain was found to be confined to the epithelial layer of the choroid plexus primordia appearing first in the fourth ventricle, followed by appearance in the lateral ventricles, and subsequently in the third ventricle. Transthyretin mRNA was localized in these cells from early stages of neuroepithelium differentiation, showing that it is a sensitive marker for the differentiation of the choroid plexus within the fetal brain.     

On the Divergence of Alleles in Nested Subsamples from Finite Populations

Within-population variation at the DNA level will rarely be studied by sequencing of loci of randomly chosen individuals. Instead, individuals will usually be chosen for sequencing based on some knowledge of their genotype. Data collected in this way require new sampling theory. Motivated by these observations, we have examined the sampling properties of a finite population model with two mutation processes and with no selection or recombination. One mutation process generates new alleles according to an infinite-alleles model, and the other generates polymorphisms at sites according to an infinite-sites model. A sample of n genes is considered. The stationary distribution of the number of segregating sites in a subsample from one of the allelic classes in the sample conditional on the allelic configuration of the sample is studied. A recursive scheme is developed to compute the moments of this distribution, and it is shown that the distribution is functionally independent of the number of additional alleles in the sample and their respective frequencies in the sample. For the case in which the sample contains only two alleles, the distribution of the number of segregating sites in a subsample containing both alleles conditional on the sample frequencies of the alleles is studied. The results are applied to the analysis of DNA sequences of two alleles found at the Adh locus of Drosophila melanogaster. No significant departure from the neutral model is detected.     

Isolation of brush-border membranes from rat and rabbit colonocytes: Is alkaline phosphatase a marker enzyme?

Summary A method for the isolation of brush-border membranes of large intestinal epithelial cells was developed, which is based on the purification of intact brush-border caps by Percoll^® density-gradient centrifugation followed by separation of the vesiculated brush-border membranes on sucrose gradients. The procedure has two major advantages in comparison to known methods: 1) its first step does not depend on the determination of marker enzymes and 2) the method is applicable to rats as well as rabbits without major modifications. Due to the lack of an accepted marker for the colonic brush-border membrane the validity of the isolation procedure was tested by its application to the small intestine. Rat small intestinal brush-border membranes were enriched 21-fold when compared to the homogenate. The method was used to evaluate alkaline phosphatase as a marker enzyme for the colonic brush-border membrane. The results suggest that alkaline phosphatase is not exclusively localized in the brush-border membrane since this enzyme was also associated with membranes having different physical properties.     

Differences in ovarian activity between booroola X merino ewes which were homozygous, heterozygous and non-carriers of a major gene influencing their ovulation rate

Differences in the function and composition of individual ovarian follicles were noted in Booroola Merino ewes which had previously been segregated on at least one ovulation rate record of greater than 5 (FF ewes, N = 15), 3-4 (F+ ewes, N = 18) or less than 3 (++ ewes, N = 18). Follicles in FF and F+ ewes produced oestradiol and reached maturity at a smaller diameter than in ++ ewes. In FF (N = 3), F+ (N = 3) and ++ (N = 3) ewes, the respective mean +/- s.e.m. diameters for the presumptive preovulatory follicles were 3.4 +/- 0.3, 4.1 +/- 0.2 and 6.8 +/- 0.3 mm and in each of these follicles the respective mean +/- s.e.m. numbers of granulosa cells (X 10(6)) were 1.8 +/- 0.3, 2.2 +/- 0.3 and 6.6 +/- 0.3. During a cloprostenol-induced follicular phase, the oestradiol secretion rates from FF ewes with 4.8 +/- 0.4 'oestrogenic' follicles, F+ ewes with 3.2 +/- 0.2 'oestrogenic' follicles and ++ ewes with 1.5 +/- 0.02 'oestrogenic' follicles were not significantly different from one another. Moreover, the mean total numbers of granulosa cells from the 'oestrogenic' follicles from each genotype were identical, namely 5.4 X 10(6) cells. Irrespective of genotype the mean weight of each corpus luteum was inversely correlated to the ovulation rate (R = 0.91, P less than 0.001). Collectively, these findings support the notion that the maturation of greater than or equal to 5 follicles in FF ewes and 3-4 follicles in F+ ewes may each be necessary to provide a follicular-cell mass capable of producing the same quantity of oestradiol as that from 1-2 preovulatory follicles in ++ ewes.     

Percutaneous transtracheal ventilation and morphometric measurements of cervical structures in swine

Fifteen swine cadavers were examined to determine a quick, reliable means of locating the level of the cricothyroid ligament from consistently palpable structures in the head and neck area. From calculations of measurements made on these cadavers, it was discovered that when a 21-43 kg pig was placed in a standard position, the measured length (L) from the angle of the mandible to the manubrium sterni multiplied by a factor of 0.48 equals the parameter Z [L (0.48) = Z]. Z was measured, beginning at the manubrium sterni, along the ventral midline. The endpoint of Z was at the level of the cricothyroid ligament. A catheter inserted at this point through the ligament into the airway provides a means of transtracheal ventilation. This method of ventilation can be used in emergencies to avoid a tracheostomy or as an alternative to endotracheal ventilation. This method was applied successfully to four anesthetized pigs as determined by a series of arterial blood gas samples.     

5,5-Diphenylhydantoin Antagonizes Neurochemical and Behavioral Effects of p, p'-DDT but Not of Chlordecone

Abstract: Rats were given 75 mg/kg of 5,5-diphenylhydantoin (phenytoin) or vehicle 30 min prior to 75 mg/kg of 1, 1, 1-trichloro-bis( p -chlorophenyl)ethane ( p, p' -DDT) (p.o.) or chlordecone (i.p.) and tremor was measured 12 h later. Rats were then killed, and regional brain levels of biogenie amines and their acid metabolites and amino acids were determined. Pretreatment with phenytoin significantly attenuated the tremor produced by p, p' -DDT but enhanced that produced by chlordecone. p, p' -DDT had significant effects on the levels of asparate, glutamate, 5-hydroxyindoleacetic acid (5-HIAA), and 3-methoxy-4-hydroxyphenylglycol (MHPG), whereas chlordecone increased glycine, 5-HIAA, and MHPG levels. Pretreatment with phenytoin blocked p.p' -DDT-induced increases of aspartate in the brainstem and spinal cord, 5-HIAA in the hippocampus, and MHPG in the brainstem and hypothalamus. Phenytoin significantly enhanced chlordecone-induced increases of MHPG in the brainstem. These data indicate that organo-chlorine-induced increases in noradrenergic activity in the brainstem and spinal cord may be directly related to the tremorigenic effects of these chemicals.     

Morphometry of monocytes of human blood

Morphometric methods have been used to analyse the ultrastructural characteristics of human blood monocytes in 20 normal adults. Data were obtained relating to whole cell, nucleus and mitochondria and, using a method not previously applied to blood cells, for the distribution of heterochromatin and euchromatin. The results provide a normal baseline against which monocyte changes in disease can be assessed.     

An interaction between season of calving and nutrition on the resumption of ovarian cycles in post-partum beef cattle

Angus cows were first mated at approximately 27 months of age in 2 herds, calving 21 July to 15 September (Group E) or 9 September to 30 October (Group L). The cows were fed a high (H) or medium (M) plane of nutrition for 55 days before and 40 days after calving. There was a mean liveweight difference of 35 kg between cows in Groups EH + LH and Groups EM + LM immediately after calving and at 40 days after calving. Immediately after calving cows in Groups EH + EM were 11 kg heavier than cows in Groups LH + LM, but there was no difference at 40 days after calving. There was a significant interaction between calving time and nutrition in the return of cyclic ovarian function assessed from both interval to first oestrus and first elevated progesterone concentration. Mean intervals from calving to first oestrus were 66.7, 82.7, 56.7 and 62.3 days in Groups EH, EM, LH and LM respectively. These data demonstrate that season of calving influences resumption of ovarian cycles even at a constant high plane of nutrition and that season of calving interacts with nutrition such that effects of season are more likely to be expressed under conditions of low nutrition.     

Effects of p,p''-DDT on the Rat Brain Concentrations of Biogenic Amine and Amino Acid Neurotransmitters and Their Association with p,p''-DDT-Induced Tremor and Hyperthermia

Male, Fischer strain 344 adult rats were given various doses (25-100 mg/kg) of p,p'-DDT by oral gavage, and levels of biogenic amines, their metabolites, and amino acid neurotransmitters, tremor activity, and rectal temperature were measured at several intervals (2, 5, 12, and 24 h) after dosing. Dose-related increases in rectal temperature and in tremor activity were observed at 50-100 mg/kg 12 h after dosing. Tremorigenic doses of DDT increased the 5-hydroxyindoleacetic acid (5-HIAA) level in hypothalamus, brainstem, and striatum, whereas doses of 75 and 100 mg/kg increased the 3-methoxy-4-hydroxyphenylglycol (MHPG) level in hypothalamus and brainstem and the 3,4-dihydroxyphenylacetic acid level in striatum. Six amino acids were assayed in the brainstem, hypothalamus, and striatum; aspartate and glutamate levels were increased only in brainstem at 25-100 mg/kg. No consistent changes in concentrations of taurine, glutamine, glycine, or gamma-aminobutyric acid were observed in any of the regions assayed. Time-related increases in rectal temperature were seen 2-12 h after dosing, and the presence of tremor was observed 5-12 h after dosing; for both the time of peak effect was at 12 h. The DDT-induced hyperthermia and tremor were associated with dose- and time-related increases in levels of 5-HIAA, MHPG, aspartate, and glutamate. It is suggested that an increase in the turnover rate of 5-hydroxytryptamine (5-HT) may be responsible for the DDT-induced hyperthermia, whereas increases in the metabolism of 5-HT and norepinephrine may be involved in the tremor.