Linkage maps of rat chromosomes 15, 16, 17, 19, and X

Linkage maps of rat chromosomes 15, 16, 17, 19, and X were constructed by multipoint genetic linkage analysis of 22 polymorphic markers in 40 F2 progeny of Fischer (F344/N) and Lewis (LEW/N) inbred rat strains. These markers are associated with eight genes (angiotensin receptor A, M3 muscarinic acetylcholine receptor, heme oxygenase, endothelin receptor A, haptoglobin, tyrosine aminotransferase, phosphoribosylpyrophosphate synthetase subunit II, and 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase) and 14 anonymous loci. Linkage analysis placed the markers into five linkage groups covering 11.7,7.9,11.6,42.5, and 5.1cM. These linkage groups were assigned to rat chromosomes 15, 16, 17, 19, and X, respectively, either by mouse x rat somatic cell hybrid analysis or based on previously identified locations of severalloci. In polymorphism analysis, these markers exhibited two to nine different alleles in 16 inbred rat strains.

Novel mouse repetitive element structures in an embryonal carcinoma mutant cell line

A mutant embryonal carcinoma (EC) cell line, NR1-6, has been isolated subsequent to infection with a retroviral insert containing a neomycin resistance cassette (Neo(r)) (1). This variant cell line has only a single insertion site, but is unique in its morphology, tumorigenicity, and differentiative potential (2). In order to understand the exact nature of the mutational event, we have sequenced the regions immediately flanking the insertion site (encompassing over 18 kb). Searches for homology in GenBank using the GCG and Blast programs have revealed homology to only a few small conserved regions (4 B1 repetitive elements approximately 150 bp long and a CA/GT dinucleotide repeat). Interestingly, B1 repetitive elements have been reported to play a role in germ cell differentiation. One of these elements is immediately 5' upstream of the insertion site and it appears as if the retroviral insertion may be responsible for activating or repressing the expression of this element. The CA/GT repeat has not yet been mapped within the mouse genome. Thus, we have identified a novel mouse locus which apparently regulates a number of cellular phenotypes.

Pancreatic microcirculation in the monkey with special reference to the blood drainage system of Langerhans islets: light and scanning electron microscopic study

The microcirculation of the pancreas in 20 monkeys (Macaca mulatta) was further studied by scanning electron microscopy (SEM) of vascular corrosion casts and light microscopy (LM) of Chinese ink-injected/cleared tissues. The results revealed that 91% of islets observed received arterial blood from the terminal branches of the intralobular arteries--the afferent arterioles, and 9% received no arterial blood, being entirely supplied by the efferent vessels of the intermediate or large islets. Some islets received blood from the translobular afferent arterioles of the adjacent lobule. Two patterns of islet drainage channels with different features in the monkey were demonstrated in our study. These patterns might be termed as continuous or convergent portal vessels. All islets possessed continuous portal vessels, 7-8 microns in diameter, which ran a short distance (approximately 100 microns) and then drained into the peri-islet acinar region, forming a typical continuous insulo-acinar portal system. About 21% of the islets possessed one or two convergent portal vessels, occasionally more. This was first observed in the monkey. These vessels were relatively long and/or thick and drained into different regions: (1) the acinar region far from the islet in the lobule, forming a convergent insulo-acinar portal system, (2) crossed the interlobular septum into an adjacent lobule where sometimes no islet existed and then drained into the exocrine acinar region, forming a translobar convergent insulo-acinar portal system, (3) drained into an adjacent small islet through the insulo-insular drainage vessels--one part of the drainage system of the islets. Translobular vascular anastomoses observed between the microcirculation of pancreatic lobules in the monkey formed a new arrangement of pancreatic microcirculation-translobular pancreatic microcirculation. The functional and clinical significance of the pancreatic portal circulation and translobular circulation is discussed in this report.

Solid-state NMR investigation of acid sites in dealuminated HZSM-5 zeolite

The acid sites and the hydration behaviors of dealuminated HZSM-5 zeolites (calcined at 550, 600, 650, and 700 degrees C) were characterized by high-resolution 1H MAS, 1H{27A1} spin-echo double resonance in combination with 27A1 MAS NMR. Apart from the usually observed peaks for dealuminated zeolite HZSM-5, a narrow plus a broad peak simultaneously appears at ca. 6.9 ppm in the 1H spectra and they exhibit different decay behavior in the 1H [27A1] double-resonance experiments. The existence of the former signal indicates that Lewis acid sites may'be formed in the zeolites after calcination. By means of the spin echo double resonance technique, we observed for the first time a previously unexpected narrow signal at 5.2 ppm, which resonates on the downfield side of Bronsted acid signal (4.3 ppm) and cannot be resolved in the 1H MAS spectra. This new signal is probably due to another kind of Bronsted acid site, locating in the small cages bounded by four- and five-membered rings. Three narrow peaks at 50 ppm, 30 ppm, and 0 ppm are superimposed on a very broad signal in the 27A1 MAS NMR spectra of dried HZSM-5. The intensity of the line at 50 ppm is significantly reduced compared with that of the rehydrated sample. 27A1 MAS NMR suggests that most part of the four-coordinated framework A1 turns into a intermediate case between four- and three-coordinated A1 after the dehydration and this process is reversible upon dehydration/rehydration. While some framework A1 atoms are transformed into three-coordinated A1 species and Lewis acid sites are, thus, generated in the dealuminated zeolites. For the signal at 30 ppm, the hydration leads to a dispersion in the chemical shift or the quadrupole interaction, which broadens its linewidth in hydrated samples.

Distinct mechanisms of upregulation of type 1A angiotensin II receptor gene expression in kidney and adrenal gland

We previously demonstrated that type 1A angiotensin II (Ang II) receptor (AT1A) is the predominant renal subtype and is upregulated by a low sodium diet. We have now tested the hypothesis that upregulation of AT1A mRNA induced by sodium deficiency is renal specific and is mediated by activation of type 1 Ang II receptor (AT1). Male Wistar rats were divided into four groups (n = 5 each) and treated for 2 weeks with normal sodium diet (0.5%), normal sodium plus 3 mg/kg per day losartan, low sodium diet (0.07%), or low sodium diet plus losartan. At the end of the 2 weeks, body weight and mean arterial pressure were not different among the four groups (P > .05). Plasma renin activity was elevated by losartan treatment, sodium restriction, or the combination of the two versus control (P < .05). Northern blot analysis showed that the ratio of renal AT1A to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA was increased by losartan treatment, sodium restriction, or the combination of the two versus control (P < .05). In contrast, the ratio of adrenal AT1A to GAPDH mRNA was increased only by sodium restriction versus three other groups (P < .05). Thus, sodium deficiency increases AT1A mRNA in both kidney and adrenal gland, while Ang II receptor blockade by losartan prevents low sodium-induced AT1A mRNA only in adrenal gland.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional distribution of messenger RNA encoding the insulin-like growth factor type 2 receptor in the rat lower brainstem

Distribution of messenger RNA (mRNA) encoding the insulin-like growth factor (IGF) type 2 receptor (IGF2R) is investigated in the rat lower brainstem by in situ hybridization histochemistry. Cells with IGF2R mRNA are distributed widely in a region-specific manner. It is expressed in: (1) motor nuclei such as the oculomotor nucleus, trochlear nucleus, motor trigeminal nucleus, abducens nucleus, facial nucleus, ambiguus nucleus, dorsal motor nucleus of vagus and hypoglossal nucleus; (2) several sensory-related nuclei like the mesencephalic trigeminal nucleus, ventral nucleus of the lateral lemniscus, lateral and spinal vestibular nuclei, ventral and dorsal cochlear nuclei and nucleus of the trapezoid body; and (3) other regions such as the red nucleus, dorsal raphe nucleus, pontine nuclei, three cerebellar nuclei (medial, interposed and lateral), Purkinje cells, cells in the granular layer of the cerebellum, locus coeruleus, several areas of the reticular nucleus and area postrema.

Genetic map of 16 polymorphic markers forming three linkage groups assigned to rat chromosome 4

Sixteen polymorphic markers, including markers for eight new loci, forming three linkage groups, were assigned to rat Chromosome (Chr) 4 by linkage analysis of the progeny of an F2 intercross of Fischer (F344/N) and Lewis (LEW/N) inbred rats. One gene, Igk, was mapped by restriction fragment length polymorphism (RFLP) analysis. One marker for Tcrb was identified by the polymorphic insertion of a repetitive LINE element. The remaining 14 markers contained polymorphic simple sequence repeats (SSRs). Ten were identified in genes (Tgfa, Npy, Prss1, Prss2, Aldr1, Iapp, Prp, Eno2, Cacnl1a1, and Il6), one was identified in a sequence related to a gene (Egr4l1), and three were identified in anonymous DNA segments. The SSR markers were highly polymorphic in 16 inbred rat strains. These markers expand the genetic map of the rat and should be useful in future genetic studies of inbred rats.

Overproduction and rapid purification of human fast skeletal beta troponin T using Escherichia coli expression vectors: functional differences between the alpha and beta isoforms

Troponin T (TpnT), an essential component of the Ca(2+)-regulatory troponin complex, is involved in protein-protein interactions with other thin-filament proteins during muscle contraction in vertebrate striated muscle (VSM). The isoforms of TpnT are encoded by members of a multigene family which, by alternate splicing, produces a complex pattern of isoproteins in VSM. The functional domains of TpnT are only tentatively identified and structure-function analysis on this protein is limited due to the heterogeneity of the multiple isoforms. We reasoned that the overproduction and purification of a single TpnT species in Escherichia coli would provide an insight into these studies, besides being useful in crystallizing the protein. We cloned the human fast skeletal beta TpnT-encoding cDNA (beta TpnTf) in three expression vectors. Overexpression was achieved in an E. coli BL21 (DE3) lysogen using a T7 RNA polymerase promoter-based vector, pET17b. The unfused recombinant protein was purified by a simple and rapid procedure in a biologically active and immunoreactive form. This is the first successful synthesis of a complete beta TpnTf polypeptide from any species using an in vitro expression system. Purified human beta TpnTf, a predominant fetal form, was less Ca(2+)-sensitive and exhibited considerably reduced affinity for troponin C and tropomyosin, as compared to the rabbit fast skeletal alpha TpnT, a predominant adult isoform. These results provide a biochemical correlate to the age-related differences in Ca2+ sensitivity of tension development in vertebrate fast skeletal muscles.

Differential regulation of angiotensin II receptor subtypes in rat kidney by low dietary sodium

This study was designed to determine whether expression of renal messenger RNA (mRNA) encoding the two known angiotensin II type 1 (AT1) receptor subtypes (AT1A and AT1B) can be regulated by dietary sodium. Seven-week-old male Wistar rats were fed a low-sodium diet (0.07%, n = 9) or a normal-sodium diet (0.5%, n = 9 [control]) for 14 days. A rat AT1 complementary DNA (cDNA) probe, which hybridizes to mRNA encoding both the AT1A and AT1B receptor subtypes, and cDNA probes, which are selective for AT1A or AT1B mRNA, were used in Northern blot or in situ hybridization analysis. By use of Northern blot analysis, renal mRNA levels for the AT1 and AT1A receptors in rats fed a low-sodium diet were found to be increased twofold (P < .05) compared with control. Because renal AT1B mRNA content was not detected by Northern blot analysis, quantitative image analysis of in situ hybridization with a digoxigenin-labeled cRNA probe made from AT1B cDNA was used. In situ hybridization analysis indicated that AT1B mRNA was expressed in the proximal and collecting tubules of the kidney in rats fed a normal-sodium diet. The low-sodium diet significantly decreased the percent positive staining area of AT1B mRNA in the renal cortex (5.51 +/- 0.77% versus 2.73 +/- 0.35%, P < .05) and medulla (4.76 +/- 0.70% versus 2.01 +/- 0.43%, P < .05) compared with the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)

A genetic map of microsatellite markers on rat chromosome 7

Nine microsatellite loci were mapped to rat Chromosome (Chr) 7 by genetic linkage and somatic cell hybrid analysis. These loci include the gene encoding a member of the IID sub-family of cytochrome P450 (Cyp2d), a gene with repetitive sequences expressed during myotube formation (D7Arb1e), four anonymous loci, D7Arb81, D7Arb208, D7Arb569, D7Arb609a, and three DNA loci defined by MapPair markers R245, R513, and R1071. The nine loci were all identified by PCR-based microsatellite polymorphism analysis and were characterized in 40 F2 intercross progeny of Fischer (F344/N) and Lewis (LEW/N) rats for segregation analysis. These markers formed a single linkage group spanning 76.8 cM with the following order and distances: D7Arb569-11.4 cM-D7Arb81-9.7 cM-R513-2.6 cM-Cyp2d-0.0 cM-R245-1.3 cM-D7Arb1e-10.4 cM-R1071-15.9 cM-D7Arb609a-15.4 cM-D7Arb208. Physical mapping of Cyp2d by somatic cell hybrid analysis allowed us to assign this linkage group to rat Chr 7. For each marker, two to six alleles were detected in a panel of 16 inbred rat strains (ACI/N, BN/SsN, BUF/N, DA/Bkl, F344/N, LER/N, LEW/N, LOU/MN, MNR/N, MR/N, SHR/N, SR/Jr, SS/Jr, WBB1/N, WBB2/N, WKY/N).

The mouse plasma membrane Ca2+ pump isoform 1 promoter: cloning and characterization

The expression of plasma membrane Ca2+ pump (PMCA) is regulated by various hormones or agonists via multiple second messenger pathways. Two different 5' segments of the PMCA1 gene (isoform 1) were cloned from a mouse genomic library. While one segment contained the 3' end of intron 1 and exon 2, the other segment was found to encompass the 5'-flanking region of the gene, exon 1, and the 5' portion of intron 1. Sequence analysis of the 5'-flanking region suggested the presence of the putative promoter. Four sites for initiation of transcription (spanning 64 bp) were identified by RNase protection assay and primer extension analysis. The promoter region was very GC-rich, contained no "TATA box," but had a "CAAT box" at -51. Comparison of sequence with known cis-regulatory motifs disclosed that the 5'-flanking region has a number of potential regulatory elements including an AP-1 site at -354, AP-2 binding sites at -267 and -123, Sp1 binding sites at -127, -111, and +3, and a cyclic AMP response element binding protein site at -67. To demonstrate promoter activity, a segment containing 611 bp of the promoter region (from -442 to +169) was subcloned in front of a promoterless chloramphenicol acetyltransferase (CAT) gene. This segment was able to drive the expression of chloramphenicol acetyltransferase in transient transfections of mouse (or human) neuroblastoma cells as well as rat aortic endothelial cells. Deletion analysis demonstrated that a fragment from -256 to +169 showed strong promoter activity, while a fragment from -117 to +169 had CAT activity that was not different from the vector control. The promoter was stimulated threefold by phorbol ester and twofold by cyclic AMP. These results provide further proof indicating up-regulation of the PMCA1 gene by multiple second messenger pathways.

Genetic map of eight microsatellite markers comprising two linkage groups on rat chromosome 6

Five genes and three anonymous DNA loci were mapped to rat chromosome 6 by genetic linkage and somatic cell hybrid analyses. The eight loci were all identified by PCR-based microsatellite polymorphism analysis and were characterized in 40 F2 intercross progeny of Fischer (F344/N) and Lewis (LEW/N) inbred rats for segregation analysis. These markers formed two linkage groups spanning, respectively, 58.1 cM and 4.0 cM. The first linkage group is comprised of two anonymous DNA loci and four genes with the following map order and distances: D6Cep8 (previously D3)-17.9 cM-D6Arb309-2.5 cM-Vsnl1 (neural visinin-like protein)-20.4 cM-Prkar2b (type IIb regulatory subunit of cAMP-dependent protein kinase)-8.8 cM-Fkhl1 (forkhead-like transcription factor BF-1)-8.5 cM-Rnu1c (18-3A U1 RNA). The second linkage group is comprised of one gene, Ckb (creatine kinase, brain) and one anonymous DNA locus, D6Arb54, separated by 4.0 cM. For each marker, two to eight alleles were detected in a panel of 16 inbred rat strains (ACI/N, BN/SsN, BUF/N, DA/Bk1, F344/N, LER/N, LEW/N, LOU/MN, MNR/N, MR/N, SHR/N, SR/Jr, SS/Jr, WBB1/N, WBB2/N, and WKY/N). Comparative mapping information indicated that rat chromosome 6 exhibits syntenic conservation with mouse chromosome 12. Homologs of the rat chromosome 6 loci have been identified on human chromosomes 2, 7, and 14.

[A brief history of the application of urethral catheterization in ancient China]

Through analysing the ancient medical literatures, the author described the types and the history of urethral catheterization in ancient China and claims that, since urethral catheterization had been used in the Jin dynasty, Sun Simiao isn't the first doctor who used this technique.

[Study on incidence of acute flaccid paralysis in Hebei]

A study on the incidence of Acute Flaccid Paralysis (AFP) among 0-14 year-old children in 1990-1992 was carried out in all over 12 prefectures and cities level hospitals in Hebei. The county level hospitals were investigated in 3 of 12 prefectures and cities. A total of 214 hospitals were investigated. The result showed that the annual average incidence of AFP and non-polio AFP among 0-14 year-old children in 1990-1992 were 1.498/100000 and 0.988/100000, respectively. The annual average incidence of them among < 5 year-old children were 2.917/100000, 1.591/100000, respectively. The incidence of AFP and non-polio AFP were different in each prefecture and city. GBS accounts for 54.06% of all AFP cases.

Overexpression and rapid purification of rabbit fast skeletal troponin I from Escherichia coli: effect of different promoters, host strains, and culture conditions

Rabbit fast skeletal troponin I (TnIf) cDNA was expressed using two Escherichia coli expression vectors, pRE1 containing the bacteriophage lambda pL promoter and pAED4, a T7 RNA polymerase-based vector. Although both vectors expressed TnIf, overexpression of the target protein was achieved with pAED4. The effect of several parameters such as culture condition, compatible host strain, and inhibition of protein synthesis by rifampicin on the expression of TnIf was investigated. The overexpressed target protein synthesized during a brief induction period of only 2 h was conveniently purified from inclusion bodies by a simple and rapid procedure involving extraction with urea, ultracentrifugation, DE-52 column chromatography, and gel filtration. About 50-75 mg of highly purified TnIf was obtained per liter E. coli culture by this method, which does not involve time-consuming multistep procedures such as affinity and ion exchange chromatography as previously reported in the literature. The isolated unfused protein is stable and is indistinguishable from native protein in all biological parameters examined. The parameters optimized in this report for overexpression of TnIf may also be applicable for other eukaryotic proteins.

Primary amino acid sequence and structure of human pyruvate carboxylase

Pyruvate carboxylase (PC) (pyruvate:carbon dioxide ligase (ADP-forming), EC 6.4.1.1.), a nuclear-encoded mitochondrial enzyme, catalyzes the conversion of pyruvate to oxaloacetate. We have isolated and characterized cDNAs spanning the entire coding region of human PC. The sequence of human PC has an open reading frame of 3537 nucleotides which encodes for a polypeptide with a length of 1178 amino acids. The identity of the cDNA as PC is confirmed by comparison to PC cDNAs of other species and sequenced peptide fragments of mammalian PC. The M(r) of the full length precursor protein is 129,576 and that of the mature apoprotein is 127,370. RNA blot analysis from a variety of human tissues demonstrates that the highest level of PC mRNA is found in liver corresponding to this tissue's high level of PC activity. Based on homology with other biotin-containing proteins, the ATP, pyruvate, and biotin-binding sites can be identified. One of two patients with documented PC deficiency was found to be missing PC mRNA, further confirming the identity of this cDNA.

A single linkage group comprising 11 polymorphic DNA markers on rat chromosome 3

Eleven polymorphic DNA markers were mapped to rat Chromosome (Chr) 3 by linkage analysis of F2 progeny of F344/N and LEW/N rat strains. The markers, including seven genes and four anonymous loci, formed a single linkage group covering approximately 112 cM with the following order: Ptgs1 (prostaglandin G/H synthase I)-D3Arb178-Scn2a (sodium channel, type II, alpha-polypeptide)-D3Arb1-Cat (catalase)-Bdnf (brain-derived neurotropic factor)-D3Arb219-D3Arb2-Sus2 (seminal vesicle secretion II protein)-Sdc4 (ryudocan/syndecan4)-Stn1 (statin-like protein). Eight of these markers were analyzed for polymorphisms in 14 additional inbred rat strains. Three to five alleles were detected for each marker, suggesting that they are highly polymorphic and useful for genetic mapping studies with inbred rat strains. Chromosomal syntenic conservation among rats, mice and humans is also discussed.

Monophyletic origin of beta-division proteobacterial endosymbionts and their coevolution with insect trypanosomatid protozoa Blastocrithidia culicis and Crithidia spp

Some trypanosomatid protozoa (order Kinetoplastida) are well known to harbor bacterial endosymbionts. Their phylogenetic positions and evolutionary relationships with the hosts were deduced by comparing the rRNA gene sequences. Earlier, we observed that these symbionts from three Crithidia spp. are identical and are closely related to Bordetella bronchiseptica. We have now sequenced the genes of another endosymbiont and the host protozoan Blastocrithidia culicis. The 16S rRNA genes of the Blastocrithidia and Crithidia symbionts share approximately 97% identity and form a distinct group, branching off the B. bronchiseptica lineage in the beta-division of Proteobacteria. Comparison of their secondary structures in the stem regions suggests compensatory mutations of the symbiont sequences, contributing to their biased base transitions from G to A and C to T. Two putative genes encoding tRNA(Ile) and tRNA(Ala) are highly conserved in the otherwise variable internal transcribed spacer region. Comparisons of the host rRNA gene sequences suggest that the symbiont-containing Crithidia and Blastocrithidia are more akin to each other than to other trypanosomatids. The evidence suggests that Blastocrithidia and Crithidia symbionts descend from a common ancestor, which had presumably entered an ancestral host and thence coevolved with it into different species. We therefore propose naming the symbionts Kinetoplastibacterium blastocrithidii and Kinetoplastibacterium crithidii.

Effects of deuterium labeling on azido amino acid mutagenicity in Salmonella typhimurium

The mutagenic effects of azide (N3-) anion in bacterial test systems require the formation of the novel mutagenic metabolite, 3-azido-L-alanine (AZAL). Although the mechanism of AZAL-induced mutagenicity is unknown, subsequent bioactivation of this metabolite appears likely. Earlier studies have shown that other azide-containing amino acids are mutagenic as well. In fact, the mutagenic potency of the synthetic AZAL homologue, L-2-amino-4-azidobutanoic acid (HomoAZAL), was several times that of AZAL. To gain insight into the biochemical processing and mutagenicity of azido amino acids in Salmonella typhimurium, several specifically deuterium-labeled azido amino acids have been prepared and tested for mutagenic potency. In addition, the effect of (aminooxy)acetic acid (AOA) (a potent inhibitor of pyridoxal-dependent processes) on AZAL-induced mutagenesis was examined. The results showed that 2-deuterium substitution of AZAL resulted in a slight increase in mutagenic potency, while AOA treatment resulted in no change in AZAL potency. Taken together these findings did not support the involvement of pyridoxal-dependent processes in AZAL bioactivation. In contrast, deuterium substitution adjacent to the azide group in HomoAZAL and 5-azido-L-norvaline (N3-Norval) resulted in a large decrease in mutagenic potency when compared to the non-deuterium labeled compounds. These observations are consistent with a bioactivation mechanism involving rate-limiting C-H bond cleavage in the formation of the ultimate mutagen. Moreover, this effect of deuterium labeling points to processing of the azide-containing side chain as a key feature in the mutagenic activation mechanism.

16S ribosomal DNA sequence identities of beta-proteobacterial endosymbionts in three Crithidia species

The 16S ribosomal DNA sequences of endosymbionts from the trypanosomatid protozoa (Crithidia spp.) are most homologous to that of Bordetella spp. This finding extends the polyphyletic origin of endosymbionts for the first time to the beta Proteobacteria. Biased base transitions and compensatory mutations of the symbionts' sequences that may contribute to their identity in the three Crithidia spp. are noted.

Isolation and characterization of human fast skeletal beta troponin T cDNA: comparative sequence analysis of isoforms and insight into the evolution of members of a multigene family

A cDNA encoding human fast skeletal beta troponin T (beta TnTf) has been isolated and characterized from a fetal skeletal muscle library. The cDNA insert is 1,000 bp in length and contains the entire coding region of 777 bp and 5' and 3' untranslated (UT) segments of 12 and 211 bp, respectively. The 3' UT segment shows the predicted stem-loop structure typical of eukaryotic mRNAs. The cDNA-derived amino acid sequence is the first available sequence for human beta TnTf protein. It is encoded by a single-copy gene that is expressed in a tissue-specific manner in fetal and adult fast skeletal muscles. Although the human beta TnTf represents the major fetal isoform, the sequence information indicates that this cDNA and the coded protein are quite distinct from the fetal and neonatal TnTf isoforms reported in other mammalian fetal muscles. The hydropathy plot indicates that human beta TnTf is highly hydrophilic along its entire length. The protein has an extremely high degree of predicted alpha-helical content involving the entire molecule except the carboxy-terminal 30 residues. Comparative sequence analysis reveals that the human beta TnTf shares a high level of sequence similarity in the coding region with other vertebrate TnTf and considerably reduced similarity with slow skeletal and cardiac TnT cDNAs. The TnT isoforms have a large central region consisting of amino acid residues 46-204 which shows a high sequence conservation both at the nucleotide and amino acid levels. This conserved region is flanked by the variable carboxy-terminal and an extremely variable amino-terminal segment. The tropomyosin-binding peptide of TnT, which is represented by amino acid residues 47-151 and also includes a part of troponin I binding region, is an important domain of this central segment. It is suggested that this conserved segment is encoded by an ancestral gene. The variable regions of vertebrate striated TnT isoforms reflect the subsequent addition and modification of genomic sequences to give rise to members of the TnT multigene family.

[Application of A-scan ultrasonography in the diagnosis and treatment of myositis of extraocular muscles (with a report of four cases)]

Four cases of myositis of extraocular muscles were diagnosed by A-scan ultrasonography. The diagnostic criteria were thickening, low reflectivity and homogeneous internal structure of affected muscles. Under the monitor of A-scan ultrasonography all cases were treated with high dose prednisone. Three of the four were cured, and one regressed. Meanwhile, the clinical manifestations and differential diagnosis of the disease are discussed briefly.

Simple sequence repeat length polymorphisms mapped to rat chromosome 11

Two genes and two anonymous DNA loci were mapped to rat chromosome 11 using F2 intercross progeny of Fischer (F344/N) and Lewis (LEW/N) inbred rats. These four loci formed a single linkage group covering 21.5 cM with the following map order: somatostatin (SST)-D11N161-D11N18-cell surface protein (MOX2). These four loci were typed by PCR-based simple sequence repeat (SSR) length polymorphism detection. For each marker four to seven different alleles were detected using a panel of 13 inbred rat strains (F344/N, LEW/N, BN/SsN, BUF/N, LER/N, MR/N, MNR/N, LOU/MN, ACI/N, WBB1/N, WBB2/N, SHR/N, WKY/N). Comparative gene mapping analysis suggests syntenic conservation between rat chromosome 11 and mouse Chromosome 16.

Nine polymorphic markers characterized by polymerase chain reaction techniques form two linkage groups on rat chromosome 8

Five genes and four anonymous polymorphic markers, forming two linkage groups, were mapped in F2 intercross progeny of F344/N x LEW/N rats using polymerase chain reaction (PCR) techniques. Both linkage groups were assigned to rat chromosome 8 because they contained genetic loci previously mapped to this chromosome. The first group was comprised of markers for three anonymous loci and two gene loci, thymus cell antigen-1 (Thy1) and tropoelastin (Eln). The second group was comprised of markers for one anonymous locus and three gene loci, cellular retinol binding protein II (Rbp2), matrin F/G (Matr1), and acyl-peptide hydrolase (Apeh). Seven markers (identified by simple sequence repeat associated length polymorphisms) were characterized in an additional 13 inbred rat strains (ACI/N, BN/SsN, BUF/N, LER/N, LOU/MN, MNR/N, MR/N, SHR/N, SR/Jr, SS/Jr, WBB1/N, WBB2/N, and WKY/N). Two to six alleles were detected for each marker. The reported markers should facilitate genetic mapping and monitoring of inbred rat strains.

Adsorption of Na+ onto gamma-alumina studied by solid-state 23Na and 27Al nuclear magnetic resonance spectroscopy

The adsorption of Na+ on gamma-alumina surfaces at four coverages of Na2CO3[5, 10, 15 and 20% w/w)] was characterized by solid-state 23Na and 27Al nuclear magnetic resonance (NMR) spectroscopy. The experimental results suggest that two distinct adsorbed species are present on the alumina surface: surface species and surface salts. At the lower coverages of Na2CO3 (5 and 10%), the surface species is predominant, in which the Na+ cations are associated with the oxygen atoms of gamma-alumina. Increasing the loading level to 15% results in the appearance of a second adsorbed species that is attributed to the surface salt, Na2CO3, deposited on the solid surface. Further adsorption of Na2CO3 leads to an increase in the amount of surface salt while the amount of surface species remains unchanged. 1H-27Al Cross-polarization magic angle spinning (CP-MAS) experiments give the evidence that some Na+ cations in the form of surface species are coordinated with the Brönsted acid sites of gamma-alumina. This may be the main driving force that improves appreciably the catalytic efficiency of an Na2CO3-Al2O3 catalyst.

Genetic map of seven polymorphic markers comprising a single linkage group on rat chromosome 5

Seven polymorphic markers comprising a single linkage group were assigned to rat Chromosome (Chr) 5 by linkage analysis of the progeny of an F2 intercross of Fischer (F344/N) and Lewis (LEW/N) inbred rats. Three genes, alpha-L-fucosidase 1 (FUCA1), mitochondrial superoxide dismutase (SOD2), and glucose transporter (GLUT1), were mapped by restriction fragment length polymorphism (RFLP) analysis. Two genes, glucose transporter (GTG3) and elastase II (ELAII), one pseudogene for alpha tubulin (TUBAPS), and one sequence related to the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene (PFKFBP1-related sequence) were mapped by simple sequence repeat (SSR) polymorphism analysis. The loci are in the following order: SOD2, GTG3/GLUT1, FUCA1, ELAII/PFKFBP1-related sequence, and TUBAPS. This linkage group covered 68.3 cM of rat Chr 5. The SSR markers were highly polymorphic in 13 inbred rat strains (SHR/N, WKY/N, MNR/N, MR/N, LOU/MN, BN/SsN, BUF/N, WBB1/N, WBB2/N, ACI/N, LER/N, F344/N, and LEW/N). These markers, located on rat Chr 5, will be useful in genetic studies of inbred rats.

Contrast-to-noise-ratio measurements in three-dimensional magnetic resonance angiography

RATIONALE AND OBJECTIVES

The authors report on the development and preliminary validation of a technique for measuring contrast-to-noise ratio (CNR) at all points along selected vessel segments in the original three-dimensional magnetic resonance angiography (MRA) dataset.

METHODS

Contrast-to-noise ratio dependencies on flow rate, field of view, and flip angle were measured on images from a conventional time-of-flight MRA pulse sequence using constant flow in a branching vascular phantom. An estimate of the inherent variability of the technique was obtained from multiple scans of a flow phantom and a human volunteer.

RESULTS

The overall standard deviation (SD) of the CNR was found to be approximately 6.1% of the average CNR value for the flow phantom study and 7.3% for the human study. Vessel CNR was found to increase with field of view and was found to become nonuniform for low flow rate and/or high flip angles.

CONCLUSION

In general, such CNR measurements allow the investigation of the mechanism of signal loss and general technique optimization in MRA.

Linkage map of nine loci defined by polymorphic DNA markers assigned to rat chromosome 13

A genetic map of nine loci defined by polymorphic DNA markers was created using a single cross of F344/N and LEW/N rats. The markers contained polymorphic simple sequence repeats identified in five genes, renin (Ren), cardiac troponin T (Tnnt3), synaptotagmin (Syt2), Na+,K(+)-ATPase catalytic subunit (Atp1a2), and the Asp-, Gly-, Glu-, and Leu-tRNA gene cluster (Trnegl), as well as four anonymous DNA segments. Analysis of the segregation of the alleles of these markers in F2 intercross progeny of F344/N and LEW/N rats indicated the following locus order and distances between pairs of loci: D13N1-5 cM-Ren-1 cM-Tntt3-0 cM-Syt2-12 cM-D13N2-25 cM-Atp1a2-0 cM-Trnegl-7 cM-D13N3-4 cM-D13N4. Three of the loci, Ren, Trnegl, and Atp1a2, have previously been assigned to rat chromosome 13. Except for Ren, none of the loci have previously been mapped by linkage analysis. The markers for these loci were characterized in a total of 13 inbred rat strains (F344/N, LEW/N, LOU/MN, WBB1/N, WBB2/N, MR/N, MNR/N, ACI/N, SHR/N, WKY/N, BN/SsN, BUF/N, and LER/N) and were found to be highly polymorphic, with two to eight alleles detected for each marker. These markers expand the genetic map of the rat and should be valuable tools for future genetic studies. An examination of human and mouse comparative map information for all loci assigned to rat chromosome 13 shows significant synteny conservation with the q arm of human chromosome 1 and the distal portion of mouse chromosome 1.

Four polymorphic markers on rat chromosome 12 form a single linkage group

Four PCR-typable polymorphic markers were mapped to rat chromosome 12 by linkage analysis of F2 intercross progeny of Fischer (F344/N) and Lewis (LEW/N) rat strains. The markers formed a single linkage group, covering 27.7 cM, with the following order and distance between markers: plasminogen activator inhibitor (Planh)--0.0 cM--phosphoenolpyruvate carboxykinase-related sequence 2 (Pepckr2)--15.4 cM--anonymous marker (D12N155)--12.3 cM--serine dehydratase (Sdh). All markers were identified and genotyped by PCR analysis of simple sequence repeats. The gene encoding Planh was previously assigned to rat chromosome 12, which allowed us to assign the entire linkage group to this chromosome. These markers were highly polymorphic in 13 additional inbred rat strains (BUF/N, BN/SsN, WKY/N, MNR/N, LER/N, WBB1/N, WBB2/N, MR/N, LOU/MN, SHR/N, ACI/N, SR/Jr, and SS/Jr). These markers should be useful tools for further genetic studies in rats.

Solid-state NMR studies of 1H spin diffusion in adsorbed organic molecules

1H spin diffusion times of toluene (MB) and tetrahydrofuran (THF) adsorbed on a series of porous solids (charcoal, SiO2 and Al2O3) were measured by a selective inversion technique. The experimental results show that they cover a wide range (from less than one millisecond to several hundreds of milliseconds). For all samples, a tri-exponential behavior was observed in the magnetization recovery processes of the negative peaks. This is attributed to the existence of the two different kinds of spin diffusion processes in addition to the T1 relaxation. One is assigned to the intermolecular spin diffusion between the surface acidic protons of the adsorbent and the organic molecules adsorbed on the solid surface, the other to the intramolecular spin diffusion of adsorbed molecules. Due to hydrogen bonding between the surface hydroxyl groups and the adsorbate, the intermolecular spin diffusion of THF adsorbed on various solids is more effective compared to that of adsorbed MB. In addition, the intermolecular 1H spin diffusion between charcoal and adsorbed THF molecules was confirmed by indirect measurement suggested by Tekely et al.

Effect of CCK-8 on audiogenic epileptic seizure in P77PMC rats

P77PMC rat is a breed of rat with congenital audiogenic seizure(AS). AS attacks were suppressed by cholecystokinin octapeptide (CCK-8) injected intraperitoneally (i.p.) at a dose of 50 micrograms/kg, but not at 25 micrograms/kg. Radioimmunoassay study showed that the CCK-8 immunoreactivity (IR) in the cerebrocortex and hippocampus is much lower in P77PMC rats than that of Wistar rats. The results suggest that a low cerebral content of CCK-8 may account for the high susceptibility of audiogenic seizure in P77PMC rats.

Characterization of a rabbit fast skeletal troponin I cDNA: a comparative sequence analysis of vertebrate isoforms and tissue-specific expression of a single copy gene

A cDNA encoding skeletal fast troponin I (TnIf) has been isolated and characterized from an adult rabbit fast skeletal muscle cDNA library. This cDNA contains the entire coding region of 549 base pairs (bp), the 3' untranslated (UT) segment of 78 bp and the 5' UT segment of 74 bp. The 3' UT segment shows the predicted stem-loop structure characteristic of eukaryotic mRNAs. The cDNA-derived amino acid sequence is not identical to the chemically-derived and the recently reported cDNA-derived amino acid sequences for rabbit TnIf, and thus enables to make the necessary corrections in the sequence information. The rabbit TnIf is encoded by a single copy gene which is expressed in adult fast skeletal muscle in a tissue-specific manner. Comparative sequence analysis of the vertebrate TnI isoforms and their cDNAs shows a high level of sequence conservation in the coding region among the TnIf interspecies isoforms. The sequence similarity is markedly decreased among the fast, slow and cardiac intra- and inter-species isoforms. The C-terminal halves of TnI isoforms including a segment believed to be involved in critical interactions with actin and troponin C (TnC) show high sequence conservation whereas the N-terminal halves show considerable difference in sequence and size. The significance of these results in relation to the biological function and evolution of members of the vertebrate TnI multigene family is discussed.

Linkage map of seven polymorphic markers on rat chromosome 18

A genetic linkage map of seven polymorphic markers was created with F2 intercross progeny of F344/N and LEW/N rats and assigned to rat Chromosome (Chr) 18. Five of the markers described were defined by simple sequence length polymorphisms (SSLPs) associated with five genes: transthyretin (TTR), trypsin inhibitor-like protein (TILP), beta 2 adrenergic receptor (ADRB2), olfactory neuron-specific G protein (OLF), and gap junction protein (GJA1). One marker was defined by a restriction fragment length polymorphism (RFLP) detected with a probe for the human colony stimulating factor 1 receptor (CSF1R) gene. The D18N1R locus was defined by an anonymous DNA fragment amplified by the randomly amplified polymorphic DNA (RAPD) technique with a single short primer. These seven DNA loci formed a single genetic linkage group 30.4 cM in length with the following order: TTR-6.8 cM-D18N1R-9.1 cM-TILP-4.3 cM-CSF1R-0 cM-ADRB2-10.2 cM-OLF-0 cM-GJA1. The five SSLP markers were highly polymorphic. In a total of 13 inbred rat strains analyzed (F344/N, LEW/N, LOU/MN, WBB1/N, WBB2/N, MR/N, MNR/N, ACI/N, SHR/N, WKY/N, BN/SsN, BUF/N, and LER/N), three to six alleles were detected for each marker. Remarkable linkage conservation was detected between the region of rat Chr 18 mapped and a region of mouse Chr 18. However, genes associated with these markers have been mapped to three different human chromosomes (Chrs 5, 6, and 18). The markers described here should be useful for genetic mapping studies and genetic monitoring of inbred rat strains.

Effects of N-acetylcysteine on diaphragmatic function and malondialdehyde content in Escherichia coli endotoxemic rats

We evaluated the effects of sublethal Escherichia coli endotoxemia with or without concomitant administration of N-acetylcysteine, an antioxidant agent, on diaphragmatic strength, endurance, and malondialdehyde (MDA) content in rats. One hundred ninety rats were inoculated subcutaneously on 2 successive days with 0.6 and 1.2 mg/100 g body weight of E. coli lipopolysaccharide respectively (E animals, n = 100) or saline (C group, n = 90). E and C animals were divided into two groups based on administration of endotoxin or saline alone (E group, n = 55; C group, n = 47, respectively) or endotoxin or saline plus N-acetylcysteine (1 g/kg body weight/day intraperitoneally) (E-NAC group, n = 45; C-NAC group, n = 43, respectively). Diaphragmatic strength was assessed in vivo 48 h after the first endotoxin or saline administration by measuring the transdiaphragmatic pressure (Pdl) generated during electrical stimulation of the phrenic nerves at 0.5, 10, 20, 30, 50, and 100 Hz. Endurance index was calculated as the percent ratio of Pdl generated after 30 s of phrenic stimulation at 10 Hz divided by the initial force. Diaphragmatic MDA (fluorometric technique) was measured 0, 6, 18, 30, 42, and 48 h after the first dose of endotoxin or saline. Pdl for 50 and 100 Hz was significantly reduced in Group E as compared with group C. This phenomenon was associated with a reduced endurance performance as assessed by a lower diaphragmatic endurance index in E as compared with C animals (90.9 +/- 4.2 versus 114.3 +/- 4.1 respectively; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

A mutation in the POU-homeodomain of Pit-1 responsible for combined pituitary hormone deficiency

Pit-1 is a pituitary-specific transcription factor responsible for pituitary development and hormone expression in mammals. Mutations in the gene encoding Pit-1 have been found in two dwarf mouse strains displaying hypoplasia of growth hormone, prolactin, and thyroid-stimulating, hormone-secreting cell types in the anterior pituitary. A point mutation in this gene was identified on one allele in a patient with combined pituitary hormone deficiency. Mutant Pit-1 binds DNA normally but acts as a dominant inhibitor of Pit-1 action in the pituitary.