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At least 865 records · Page 48Linked to original sources
PubMed1999

Stented segment length as an independent predictor of restenosis.

OBJECTIVES: We sought to evaluate the relation between stented segment length and restenosis. BACKGROUND: Multiple or long coronary stents are now being implanted in long lesions or in tandem lesions. A longer stented segment might result in a higher probability of restenosis. However, there is little information available on the relation between stented segment length and restenosis. METHODS: Between April 1995 and December 1996, 725 patients with 1,090 lesions underwent stenting. Lesions were divided into three groups according to the length of the stented segment: 1) group I (n = 565): stented segment length < or =20 mm; 2) group II (n = 278): stented segment length >20 but < or =35 mm; and 3) group III (n = 247): stented segment length >35 mm. RESULTS: There was no significant difference in the incidence of subacute stent thrombosis among the three groups (0.4% in group I, 0.4% in group II, 1.2% in group III; p = NS). The minimal lumen diameter (MLD) after stenting was greater in group I than in group III (3.04 +/- 0.60 mm in group I, 3.01 +/- 0.54 mm in group II, 2.91 +/- 0.58 mm in group III; p < 0.05). At follow up, a smaller MLD was observed in group III as compared with group I and group II (2.04 +/- 0.93 mm in group I, 1.92 +/- 1.00 mm in group II, 1.47 +/- 0.97 mm in group III; p < 0.01). The restenosis rates were 23.9% in group I, 34.6% in group II and 47.2% in group III (p < 0.01). Using multivariate analysis, the longer stented segment, the angiographic reference vessel diameter and the percent diameter stenosis after stenting were independent predictors of restenosis. CONCLUSIONS: The present study shows that a longer stented segment is an independent predictor of restenosis without an influence on the risk of subacute thrombosis.

Aged↗
PubMed1998

Segment-oriented hepatic resection in the management of malignant neoplasms of the liver.

BACKGROUND: Improvements in the understanding of intrahepatic anatomy and radiographic technology have facilitated a segment-oriented approach to liver resection. This approach involves the resection of isolated anatomic segments or sectors of the liver as dictated by the extent of the intrahepatic pathology. Segment-oriented resection allows maximal conservation of normal liver parenchyma while clearing tumor. This report describes the technical features and the results of a prospective evaluation of segmental and sectoral resections in the treatment of malignant hepatic neoplasms. STUDY DESIGN: Patients with malignant hepatic neoplasms that were treated with a segment-oriented hepatic resection were identified from a prospective clinical data base. After undergoing segment-oriented liver resection, the patients were followed at regular intervals. Recurrent disease was the end point of the study. Followup is reported at a median of 12 months. This review outlines the technique of resection, intraoperative events, operating time, blood loss, and the ability to obtain negative resection margins. RESULTS: During the 5-year period between July 1992 and July 1997, 400 patients underwent liver resection for metastatic neoplasms and hepatocellular carcinoma (HCC). During this period, 79 patients (20%) were treated with a segment-oriented resection. These patients represent the study group for this report. The overall mortality rate was 2.5%; all postoperative deaths occurred in patients with HCC and cirrhosis. Overall morbidity was 26%. The median hospital stay was 8 days. Mean transfusion requirements were 1.0 +/- 0.3 U of packed red blood cells. Patients with HCC showed a greater transfusion requirement than did patients without HCC: 2.7 +/- 1.2 U versus 0.6 +/- 0.2 U (p < 0.05). Of the patients without HCC, 17% required transfusion. During the 12-month median followup period, the overall disease recurrence rate was 23%. Disease recurred at the hepatic-resection margin in 2.5% of the patients. CONCLUSIONS: Segmental resection is a safe technique that allows complete resection of liver tumors with preservation of normal liver parenchyma. Segmental resection is particularly useful for patients with HCC and patients undergoing repeat liver resections or bilobar resections.

Adult↗
PubMedDate not supplied

Gastroesophageal reflux disease and mucosal injury with emphasis on short-segment Barrett's esophagus and duodenogastroesophageal reflux.

Gastroeosphageal reflux disease has been associated with long segments of Barrett's esophagus </=3 cm), but little is known about its association with shorter segments. The aim of this study was to evaluate anatomic and physiologic alterations of the cardia and esophageal exposure to gastric and duodenal juice in patients with short and long segments of Barrett's esophagus. Furthermore, these patients were compared to each other and to patients with erosive esophagitis and those with no mucosal injury. Two hundred sixty-two consecutive patients with foregut symptoms were divided into the following four groups based on endoscopic and histologic findings: group 1, no mucosal injury; group 2, erosive esophagitis; group 3, short-segment Barrett's esophagus; and group 4, long-segment Barrett's esophagus. Esophageal exposure time to acid and bilirubin, lower esophageal sphincter characteristics, and endoscopic anatomy of the cardia were compared between the groups. Patients with short-segment Barrett's esophagus had elevated esophageal acid and bilirubin exposure, decreased lower esophageal sphincter pressure and length, and a high incidence of hiatal hernia. These abnormalities were similar to those in patients with esophagitis and in general less profound than those found in patients with long-segment Barrett's esophagus. The length of intestinal metaplasia was higher in patients with a defective lower esophageal sphincter. Short-segment Barrett's esophagus is a complication of severe gastroesophageal reflux disease and is associated with the reflux of both gastric and duodenal juice similar to that seen in patients with long-segment Barrett's esophagus.

Adult↗
PubMed2002

Nucleotide sequences of double-stranded RNA segments from a hypovirulent strain of the white root rot fungus Rosellinia necatrix: possibility of the first member of the Reoviridae from fungus.

Twelve double-stranded (ds) RNA segments were detected from a hypovirulent strain W370 of the white root rot fungus Rosellinia necatrix. The estimated molecular weights ranged from 0.41 x 10(6) to 2.95 x 10(6). Full length cDNA clones for eight segments were obtained. Northern blot analysis suggested that each segment was genetically unique. The nucleotide sequences of eight full length dsRNA segments were determined. One long open reading frame was found in each segment. Conserved sequences at the 5'-end (5'-ACAAUUU-3') and at the 3'-end (5'-UGCAGAC-3') were identified in all eight segments. Segment-specific panhandle structures, formed by inverted terminal repeats, were also found in all segments. Comparative analyses of the predicted translational products of eight dsRNA segments showed that the deduced amino acid sequence partially matched those of the Reoviridae family members: Colorado tick fever virus, Nilaparvata lugens reovirus, and rice black streaked dwarf virus. The results suggested that W370 dsRNA is derived from a new member of the family Reoviridae detected in fungus.

3' Untranslated Regions↗
PubMed2001

When body segmentation goes wrong.

The segmented or metameric aspect is a basic characteristic of many animal species ranging from invertebrates to man. Body segmentation usually corresponds to a repetition, along the anteroposterior (AP) axis, of similar structures consisting of derivatives from the three embryonic germ layers. In humans, segmentation is most obvious at the level of the vertebral column and its associated muscles, and also in the peripheral nervous system (PNS). Functionally, segmentation is critical to ensure the movements of a rod-like structure, such as the vertebral column. The segmented distribution of the vertebrae derives from the earlier metameric pattern of the embryonic somites. Recent evidence from work performed in fish, chick and mouse embryos indicates that segmentation of the embryonic body relies on a molecular oscillator called the segmentation clock, which requires Notch signaling for its proper functioning. In humans, mutations in genes required for oscillation, such as Delta-like 3 (DLL3), result in abnormal segmentation of the vertebral column, as found in spondylocostal dysostosis syndrome, suggesting that the segmentation clock also acts during human embryonic development.

Animals↗
PubMed1980

Embryogenesis in a Drosophila mutant expressing half the normal segment number.

Insect segments are seriated developmental subunits whose borders largely control intra-segmental patterning. The individual segment owes its specific character to position-dependent instructions given to its early embryonic progenitor cells. In Drosophila, the segment borders first become visible as a series of transverse infoldings on the surface of the germ band. We describe here development in a mutant (prdFR1) which forms half the normal number of transverse infoldings spaced at twice the normal distance, thereby subdividing the germ band into a series of giant domains (Fig. 1 a-c). Each domain develops the tracheal pits of two normal segments (Fig. 1e), thus revealing its composite origin, but the larva expresses only one segment border per domain and the cuticle between these borders is similar to the normal segment in both size and zonation (Fig. 2). We conclude that this course of development reflects a conflict between the seriated instructions specifying local segment character (see Fig. 1b) and controlling influences exerted by the abnormally spaced infoldings and later by the definitive segment borders.

Animals↗
PubMed2003

Involvement of Notch and Delta genes in spider segmentation.

It is currently debated whether segmentation in different animal phyla has a common origin and shares a common genetic mechanism. The apparent use of different genetic networks in arthropods and vertebrates has become a strong argument against a common origin of segmentation. Our knowledge of arthropod segmentation is based mainly on the insect Drosophila, in which a hierarchical cascade of transcription factors controls segmentation. The function of some of these genes seems to be conserved among arthropods, including spiders, but not vertebrates. The Notch pathway has a key role in vertebrate segmentation (somitogenesis) but is not involved in Drosophila body segmentation. Here we show that Notch and Delta genes are involved in segmentation of another arthropod, the spider Cupiennius salei. Expression patterns of Notch and Delta, coupled with RNA interference experiments, identify many similarities between spider segmentation and vertebrate somitogenesis. Our data indicate that formation of the segments in arthropods and vertebrates may have shared a genetic programme in a common ancestor and that parts of this programme have been lost in particular descendant lineages.

Animals↗
PubMed1999

Evaluation of ureteric contraction: a comparison among ring, spiral-cut and longitudinal segments.

OBJECTIVE: To determine the optimal contractile response of isolated ureters to inflammatory mediators and neurotransmitters by evaluating four common methods of ureteric suspension. MATERIALS AND METHODS: Ureters from adult domestic swine were placed immediately in Krebs buffer and cut into 4-5 mm segments. Four methods of suspension were compared: (i) an unopened ring segment suspended horizontally; (ii) a spirally cut segment (lumen cut open at a 45 degrees and suspended end-to-end); (iii) an open longitudinal segment; and (iv) a closed longitudinal segment. All segments were placed in individual water-jacketed tissue baths containing Krebs buffer, the frequency of contraction measured using a force transducer and registered on a polygraph. The sensitivity of all four segments was tested by measuring the tension and frequency in response to increasing frequencies of electric field stimulation, and by a cumulative concentration-response curve to carbachol. RESULTS: Ureteric segments responded with an increased frequency of contraction depending on the intensity of stimulus to both electric field stimulation and carbachol. However, there were no significant differences in spontaneous levels of contraction, sensitivity or maximal response among the methods of suspension in response to electric field stimulation or carbachol. CONCLUSION: These results indicate that all four methods of suspending the ureteric segments produce contractile responses sensitive enough to study the action of various neurotransmitters.

Animals↗
PubMed2001

Ethnic differences in the ST segment of the electrocardiogram: a comparative study among six ethnic groups.

Deviation of the ST segment of the electrocardiogram (ECG) may signify infarction or ischemia. Prior studies suggest that normal ECG patterns may differ among ethnic groups. We retrospectively reviewed the first thousand medical files of a multiethnic community, where all individuals shared similar living conditions. Only healthy adults, aged 15 to 60 years, were included. Along with age, the most common causes for exclusion were diabetes, hypertension, and ischemic heart disease. A total of 597 subjects (349 men) were included: 350 Saudi Arabians, 39 Filipinos, 95 Indians, 17 Sri-Lankans, and 57 Caucasians. Twenty men and one woman had an ECG pattern of early repolarization (ST segment elevation with upward concavity, notching on QRS, and large symmetrical T wave), with no difference in incidence among ethnic groups. ST segment elevation (2 mm in any of the leads V1-V4, or 1 mm in any of the other leads) without criteria of early repolarization occurred in 11.58%, 13.46%, 3.57%, 4.35%, 11.76%, 7.32% of Saudi, Indian, Jordanian, Filipino, Sri-Lankan, and Caucasian men, respectively (P =.61). Only one Jordanian and 2 Indian women had this pattern. However, Filipino men had higher median ST segment levels than others in leads V1 and V3. Among women, the median ST segment level was iso-electric in all leads in all ethnic groups. Only 3 subjects had ST segment depression >1 mm. Significant ST segment elevation is common in normal healthy men but may not fulfill criteria for early repolarization; it has no ethnic predilection. ST segment elevation is uncommon in normal women. ST segment depression is a rare finding in healthy adults regardless of ethnic origin.

Adolescent↗
PubMed2003

Role of superficial venous surgery in patients with combined superficial and segmental deep venous reflux.

OBJECTIVES: superficial venous surgery heals chronic venous ulceration (CVU) in the majority of patients with isolated superficial venous reflux (SVR). This study examines the role of superficial venous surgery in patients with combined SVR and segmental deep venous reflux (DVR). METHODS: combined SVR and segmental DVR was diagnosed by venous duplex in 53 limbs in 49 patients (24 men and 25 women of median age 66, range 27-90, years). Fourteen limbs had varicose veins (CEAP class 2-4) and 39 (74%) had active CVU (CEAP class 6). Duplex ultrasound was performed before and three months after local anaesthetic superficial venous surgery. Perforator vein surgery, skin grafting and compression bandaging or hosiery were not used. RESULTS: forty-two limbs with long saphenous vein (LSV) reflux underwent sapheno-femoral disconnection, 10 with short saphenous vein (SSV) reflux underwent sapheno-popliteal disconnection and one limb with LSV and SSV reflux had sapheno-femoral and sapheno-popliteal disconnection. Segmental DVR was confined to the superficial femoral vein (SFV) in 16 limbs, below knee popliteal vein (BKPV) in 25 and gastrocnemius vein (GV) in 12 limbs. Overall, duplex demonstrated post-operative resolution of segmental DVR in 26 of 53 (49%) limbs. Resolution of segmental SFV reflux occurred in 12 of 16 (75%) limbs compared with 14 of 37 (38%) limbs with segmental BKPV or GV reflux (p=0.018). Segmental DVR resolved in 19 of 39 (49%) limbs with CVU and ulcer healing occurred in 30 of 39 (77%) limbs at 12 months with a median time to healing of 61 (range 14-352) days. Segmental DVR resolved in 14 of 30 (47%) limbs with a healed ulcer: 7 of 9 (78%) limbs with SFV and 7 of 21 (33%) with BKPV or GV reflux (p=0.046). CONCLUSIONS: these data demonstrate that in patients with combined SVR and segmental DVR, superficial venous surgery alone corrects DVR in almost 50% of limbs and is associated with ulcer healing in 77% of limbs at 12 months. These findings suggest an extended role for superficial venous surgery in the management of patients with complicated venous disease.

Adult↗
PubMed2002

Volumetric analysis of liver segments in 155 living donors.

Right-lobe graft has been used most frequently for living donor liver transplantation in adult patients; however, some donors cannot donate their right lobe (according to the Healey and Scroy's terminology) because the remaining residual liver would be too small. A recent study suggested the possibility of right posterior segment graft in these donors. The purpose of this study was to evaluate the feasibility of right lobe or right posterior segment graft with a volumetric analysis. Liver volumetry by computed tomography was performed in 155 consecutive donors, and the volume of each liver segment was calculated. To confirm the reliability of volumetric examination, the estimated graft volume and the actual weight were compared. The average volume ratios of the left lateral segment, left medial segment, caudate lobe, right anterior segment, and right posterior segment were 17%, 14%, 2%, 37%, and 30%, respectively. In 39 donors (25%), the volume ratio of the right lobe was over 70%. Of these donors, 72% had a larger (difference in volume ratio greater than 5%) right posterior segment than left lobe with caudate lobe. The relationship between the estimated volume and actual weight was linear. The present results suggest that right lobectomy carries a potential risk and that the right posterior segment may be useful as an alternative graft from the point of donor's safety.

Adolescent↗
PubMed2000

Prevention of paraplegia in pigs by selective segmental artery perfusion during aortic cross-clamping.

PURPOSE: During thoracoabdominal aortic aneurysm repair, a prolonged interruption of the spinal cord blood supply can result in irreversible spinal cord damage. The aim of this study was to investigate whether selective segmental artery perfusion during aortic clamping could prevent paraplegia in pigs. METHODS: Specially designed segmental artery perfusion catheters, which could be attached to an extracorporeal bypass graft system, were used. In experiment I (n = 10), it was assessed whether selective segmental artery perfusion could reverse electrophysiologic evidence of spinal cord ischemia and maintain transcranial motor evoked potentials (tc-MEPs) during 60 minutes of aortic cross-clamping. The abdominal aorta, containing critical segmental arteries, was bypassed through use of an aortoaortic bypass graft system. After the disappearance of tc-MEPs, an aortotomy was followed by selective segmental artery perfusion. In experiment II (n = 10), the aim was to determine whether selective segmental artery perfusion could prevent paraplegia. In five animals (group A), aortic cross-clamping was followed by selective segmental artery perfusion; five control animals (group B) underwent segmental artery blockade only. Postoperative hind limb function and spinal cord histopathology were evaluated on the third postoperative day. RESULTS: In experiment I, tc-MEPs disappeared within 3.7 +/- 3.7 minutes after cross-clamping and returned in all animals in 8.5 +/- 5.3 minutes after selective perfusion. During the study period, tc-MEP amplitudes recovered to a median of 49% (range, 28%-113%) of baseline values. Total bypass graft flow was 880 +/- 294 mL/min, of which 184 +/- 54 mL/min was directed to the selective perfusion catheters. The flow in individual catheters was 52 +/- 13 mL/min. In experiment II, all perfused animals demonstrated normal hind limb function, whereas four of five control animals were paraplegic on day 3 (P =.04) In the perfused animals, histopathologic examination showed either no spinal cord damage or eosinophilic neurons only, whereas in paraplegic controls there was infarction in large areas of the cord (P <.0001). CONCLUSION: In pigs, selective segmental artery perfusion can provide sufficient spinal cord blood flow to prevent paraplegia resulting from 60 minutes of aortic clamping, as shown by clinical outcomes and histopathologic examination.

Animals↗
PubMed2003

Selective incorporation of influenza virus RNA segments into virions.

The genome of influenza A virus is comprised of eight viral RNA (vRNA) segments. Although the products of all eight vRNA segments must be present for viral replication, little is known about the mechanism(s) responsible for incorporation of these segments into virions. Two models have been proposed for the generation of infectious virions containing eight vRNA segments. The random-incorporation model assumes a common structural feature in all the vRNAs, enabling any combination of vRNAs to be incorporated randomly into virions. The selective-incorporation model predicts the presence of specific structures in each vRNA segment, leading to the incorporation of a set of eight vRNA segments into virions. Here we demonstrate that eight different vRNA segments must be present for efficient virion formation and that sequences within the coding region of (and thus unique to) the neuraminidase vRNA possess a signal that drives incorporation of this segment into virions. These findings indicate a unique contribution from individual vRNA segments and thus suggest a selective (rather than random) mechanism of vRNA recruitment into virions. The neuraminidase vRNA incorporation signal and others yet to be identified should provide attractive targets for the attenuation of influenza viruses in vaccine production and the design of new antiviral drugs.

Animals↗
PubMed2006

A pair-rule gene circuit defines segments sequentially in the short-germ insect Tribolium castaneum.

In Drosophila, a hierarchy of maternal, gap, pair-rule, and segment polarity gene interactions regulates virtually simultaneous blastoderm segmentation. For the last decade, studies have focused on revealing the extent to which Drosophila segmentation mechanisms are conserved in other arthropods where segments are added sequentially from anterior to posterior in a cellular environment. Despite our increased knowledge of individual segmentation genes, details of their interactions in non-Drosophilid insects are not well understood. We analyzed the Tribolium orthologs of Drosophila pair-rule genes, which display pair-rule expression patterns. Tribolium castaneum paired (Tc-prd) and sloppy-paired (Tc-slp) genes produced pair-rule phenotypes when their transcripts were severely reduced by RNA interference. In contrast, similar analysis of T. castaneum even-skipped (Tc-eve), runt (Tc-run), or odd-skipped (Tc-odd) genes produced severely truncated, almost completely asegmental phenotypes. Analysis of interactions between pair-rule components revealed that Tc-eve, Tc-run, and Tc-odd form a three-gene circuit to regulate one another as well as their downstream targets, Tc-prd and Tc-slp. The complement of primary pair-rule genes in Tribolium differs from Drosophila in that it includes Tc-odd but not Tc-hairy. This gene circuit defines segments sequentially in double segment periodicity. Furthermore, this single mechanism functions in the early blastoderm stage and subsequently during germ-band elongation. The periodicity of the Tribolium pair-rule gene interactions reveals components of the genetic hierarchy that are regulated in a repetitive circuit or clock-like mechanism. This pair-rule gene circuit provides insight into short-germ segmentation in Tribolium that may be more generally applicable to segmentation in other arthropods.

Animals↗
PubMed1982

Recent duplication and germ-line diversification of rat immunoglobulin kappa chain gene joining segments.

Sequence determination of the joining segment gene (J) cluster in the kappa chain (J kappa) in the embryonic context demonstrates that rat genome contains seven J kappa gene segments that expanded from an ancestral cluster of five J kappa genes. The rat J segments are separated by about 300 base pairs (bp) and are flanked 5' by the presumed variable region (V)/J recombination signal sequence and 3' by the RNA splicing signal. Two of the J gene segments designated J2A and J2B and their 5'-flanking spacer DNA bear striking homology to J2 and its 5'-flanking spacer. Thus, the unit of duplication was the entire J kappa coding region and 5' noncoding spacer (345 bp). The duplication probably occurred as two separate unequal crossing-over (UXO) events. The first UXO event can be confined to recombination within an identical stretch (14 bp long) located at the 3' ends of the coding regions of J1 and J2. The second event could involve a longer segment (372 bp) of tight homology generated by the first UXO event, thus increasing the probability of repeated expansion of the same DNA segment. The sequence homology among the rat duplicated segments (98-99%) is larger than the homology between the corresponding rat and mouse segments (89%), showing that the rat J kappa gene expansion must have occurred after rat and mouse divergence 10 X 10(6) yr ago. We estimate that the first and second UXO events occurred 2 X 10(6) and 1 X 10(6) yr ago, respectively. J3 of rat and mouse share the same mutation (G leads to C) in the RNA splicing signal that presumably inactivates J3. This mutation preceded divergence of the two species. A mutation in the first nucleotide of codon 96 has occurred in both duplicated segments, the only position along 345 bp where J2, J2A, and J2B differ from each other. This results in three different amino acids at position 96 not present in any other J kappa. These mutations are physiologically significant because they diversify the third complementarity-determining region (CDR3) and, thus, may reflect selective pressure to increase antibody diversity. The germ-line diversification of CDR3 was exercised within the last 1-2 X 10(6) yr.

Amino Acid Sequence↗
PubMed1984

Restricted association of V and J-C gene segments for mouse lambda chains.

The frequencies of diverse rearrangements of variable (V)lambda to joining (J)lambda gene segments were examined by Southern blot hybridization in 30 murine B-cell lines, each producing an immunoglobulin lambda light chain of known subtype (lambda 1, lambda 2, or lambda 3). For 11 out of 12 lambda 1 chains, the rearrangement was V lambda 1----J lambda 1; for 9 out of 9 lambda 2 chains, it was V lambda 2----J lambda 2; and for 8 out of 9 lambda 3 chains, it was V lambda 1----J lambda 3. Similar results were obtained by considering the partial or complete sequences at the amino acid or cDNA level of 44 other lambda chains (24 previously described): for 43 of these chains the rearranged V-J gene segments were evidently V lambda 1-J lambda 1 for 28 lambda 1 chains, V lambda 2-J lambda 2 for 10 lambda 2 chains, and V lambda 1-J lambda 3 for 5 lambda 3 chains. Of the combined total of 74 chains there were 3 with unusual V lambda rearrangements, all involving the V lambda 2 gene segment: for 2 of these unusual chains, the encoding segments were V lambda 2-J lambda 1-C lambda 1 and for one they were V lambda 2-J lambda 3-C lambda 3. Thus, the results for all 74 lambda chains show that, in contrast to the apparently unrestricted V kappa----J kappa rearrangements for kappa chains, for each of the 3 murine lambda-chain subtypes V-J recombination is severely restricted: the V lambda gene segment expressed in lambda 1 and lambda 3 chains was nearly always V lambda 1 (95% and 93%, respectively), whereas in lambda 2 chains it was without exception V lambda 2 (19 out of 19 chains). Therefore V lambda-J lambda combinatorial variation is not a significant source of amino acid sequence diversity of lambda chains of inbred mice. If the order of the lambda gene segments is 5' V lambda 2-J lambda 2C lambda 2J lambda 4C lambda 4-V lambda 1-J lambda 3C lambda 3J lambda 1C lambda 1 3', as suggested previously and by the present findings, it appears that (i) when a V lambda gene segment rearranges in a developing B cell it ordinarily recombines with a J lambda gene segment in the nearest downstream (3') cluster of J lambda C lambda segments, and (ii) V lambda rearrangement to the upstream (5') cluster is very rare and possibly may not take place at all.

Animals↗
PubMed1985

Preferential rearrangement of the immunoglobulin kappa chain joining region J kappa 1 and J kappa 2 segments in mouse spleen DNA.

The V kappa-KpnI family, which constitutes approximately equal to 36% of mouse kappa chain variable region gene (V kappa) segments, conserves the Kpn I site (G-G-T-A-C-C) at the position corresponding to residues 35-37. Using this cleavage site, we were able to assess the relative recombination frequency of the kappa chain joining region gene (J kappa) segments in mouse spleen DNA. The J kappa 1 and J kappa 2 segments were used 2- to 5-fold more frequently than were the J kappa 4 and J kappa 5 segments. The J kappa 3 segment was shown to be incapable of recombining with the V kappa segment. The relative recombination frequency of the J kappa segments did not change significantly by lipopolysaccharide stimulation of normal mouse spleens. The relative frequency of the J kappa usage was unaltered in immune disorders such as in nude (nu/nu), MRL (lpr/lpr), and BXSB mice. Seven V kappa-KpnI-J kappa 1 clones were isolated, and their nucleotide sequences were determined. Two of them were derived from the identical germ-line V kappa segment but differed in the nucleotide sequence of the V-J junction. The maximal number of V kappa germ-line segments was estimated to be less than 300 by statistical calculation.

Animals↗
PubMed1995

Identification of signals required for the insertion of heterologous genome segments into the reovirus genome.

In cells simultaneously infected with any two of the three reovirus serotypes ST1, ST2, and ST3, up to 15% of the yields are intertypic reassortants that contain all possible combinations of parental genome segments. We have now found that not all genome segments in reassortants are wild type. In reassortants that possess more ST1 than ST3 genome segments, all ST1 genome segments appear to be wild type, but the incoming ST3 genome segments possess mutations that make them more similar to the ST1 genome segments that they replace. In reassortants resulting from crosses of the more distantly related ST3 and ST2 viruses that possess a majority of ST3 genome segments, all incoming ST2 genome segments are wild type, but the ST3 S4 genome segment possesses two mutations, G74 to A and G624 to A, that function as acceptance signals. Recognition of these signals has far-reaching implications for the construction of reoviruses with novel properties and functions.

Animals↗