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PubMedDate not supplied

Topological and segmental phylogenetic analyses of the anion exchanger (band 3) family of transporters.

Eleven sequenced anion exchanger (AE; band 3) proteins, including five AE1, four AE2 and two AE3 proteins, comprise the anion exchanger family (AEF) of homologous proteins. Eliminating the rat and rabbit proteins that are nearly identical to the corresponding mouse proteins, seven dissimilar members of this family were selected for study, divided into N-terminal, central and C-terminal segments (designated segments 0, 1 and 2, respectively) and analysed separately for sequence similarity and phylogenetic relatedness. Segments 0 are variable in length and sequence, are essentially lacking in some of the members of the AEF, and are not demonstrably homologous in other members of the family. All segments 1 and 2 are homologous, but they exhibit widely differing degrees of sequence divergence. Segments 2 are highly conserved in all AEF proteins. Segments 1 of the AE2 and AE3 proteins are as conserved as are segments 2, but segments 1 of the AE1 proteins have diverged from each other and from the AE2 and AE3 segments 1 much more than have segments 2 of these same proteins. The distributions of various types of amino acid residues in the putative transmembrane helical spanners of the seven dissimilar members of the AEF, based on a modification of the 14-spanner model of Wang et al. (1994) was determined, and this distribution was compared with those of other transmembrane transport proteins of known structure (bacterial rhodopsins, outer membrane porins of Gram-negative bacteria and bacterial photosynthetic reaction centres.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2000

Effect of segment length on risk for neoplastic progression in patients with Barrett esophagus.

BACKGROUND: The increased risk for esophageal adenocarcinoma associated with long-segment (> or =3 cm) Barrett esophagus is well recognized. Recent studies suggest that short-segment (<3 cm) Barrett esophagus is substantially more common; however, the risk for neoplastic progression in patients with this disorder is largely unknown. OBJECTIVE: To examine the relation between segment length and risk for aneuploidy and esophageal adenocarcinoma in patients with Barrett esophagus. DESIGN: Prospective cohort study. SETTING: University medical center in Seattle, Washington. PATIENTS: 309 patients with Barrett esophagus. MEASUREMENTS: Patients were monitored for progression to aneuploidy and adenocarcinoma by repeated endoscopy with biopsy for an average of 3.8 years. Cox proportional hazards analysis was used to calculate adjusted relative risks and 95% Cls. RESULTS: After adjustment for histologic diagnosis at study entry, segment length was not related to risk for cancer in the full cohort (P > 0.2 for trend). When patients with high-grade dysplasia at baseline were excluded, however, a nonsignificant trend was observed; based on a linear model, a 5-cm difference in segment length was associated with a 1.7-fold (95% CI, 0.8-fold to 3.8-fold) increase in cancer risk. Among all eligible patients, a 5-cm difference in segment length was associated with a small increase in the risk for aneuploidy (relative risk, 1.4 [CI, 1.0 to 2.1]; P = 0.06 for trend). A similar trend was observed among patients without high-grade dysplasia at baseline. CONCLUSIONS: The risk for esophageal adenocarcinoma in patients with short-segment Barrett esophagus was not substantially lower than that in patients with longer segments. Although our results suggest a small increase in risk for neoplastic progression with increasing segment length, additional follow-up is needed to determine whether the patterns of risk occurred by chance or represent true differences. Until more data are available, the frequency of endoscopic surveillance should be selected without regard to segment length.

Adenocarcinoma↗
PubMed2001

Survey of use of ST-segment monitoring in patients with acute coronary syndromes.

BACKGROUND: Although effective for assessing ongoing myocardial ischemia, ST-segment monitoring may be underused. OBJECTIVES: To determine the proportion of cardiac units in the United States that use ST-segment monitoring, hospital and unit characteristics associated with its use, how units use such monitoring with respect to research recommendations, if units that use ST-segment monitoring find it clinically useful and easy to use, and why some units are not using this type of monitoring. METHODS: A survey on ST-segment monitoring was mailed to a random sample of 500 cardiac nurse managers and clinical nurse specialists. RESULTS: Of the final 192 respondents, 104 (54.2%) reported that they were using ST-segment monitoring. Monitor brand was the only characteristic associated with use of this monitoring (P = .03). On units that used ST-segment monitoring, patients were monitored if they had myocardial infarction (81%), unstable angina (79.6%), or possible myocardial infarction (78.6%) and after percutaneous transluminal coronary angioplasty (47.6%). Leads were chosen according to unit protocol (60.2%) and 12-lead electrocardiographic findings (48.5%); leads II (95.0%) and V1 (75.2%) were used most often. The majority of units that use ST-segment monitoring agreed that it is clinically useful (83%) and easy to use (56%). Among the units not using ST-segment monitoring, the most common reason was that physicians were not interested (27.1%). CONCLUSIONS: ST-segment monitoring is not routinely used; when it is, research recommendations are often not followed. Increased awareness is needed among cardiac nurses and physicians of the clinical usefulness and proper use of ST-segment monitoring.

Acute Disease↗
PubMed2002

[Rapid resolution of ST segment elevation predicts recovery of left myocardial contraction in patients with acute myocardial infarction treated with percutaneous coronary angioplasty].

BACKGROUND: Early epicardial vessel patency and tissue perfusion limit infarct size, improve survival and are crucial for optimum functional recovery of the ischaemic myocardium in patients with acute myocardial infarction (AMI). Coronary angiography has been considered the "gold standard" in assessment of reperfusion. Restoration of coronary patency is not a guarantee of myocardial cellular perfusion. ST-segment elevation resolution observed in electrocardiogram (ECG) early after initiation of primary PTCA could be potentially correlated with reperfusion. AIM: The aim of the study was the prospective assessment of left ventricular (LV) contractility recovery in patients after primary PTCA for AMI in 3 and 6 month follow-up according to early ST-segment elevation resolution analysis. METHODS: 111 consecutive patients (80 men and 31 women age 36-78) with AMI treated by successful primary PTCA (Thrombolysis in Myocardial Infarction grade 3 flow and residual stenosis less than 30%) within 12 h of chest pain onset were enrolled in the study. 12-lead ECG was performed on admission and 1 hour after the beginning of the PTCA. The patients were divided into 2 groups according to ST-segment elevation resolution in the ECG (> 50% depression of the elevated ST-segment) within 1 hour after the procedure. The mean pain-to-balloon time was not significantly different in both groups. In each patient, global ejection fraction (EF) and wall motion index (WMI) were derived immediately after primary PTCA and after 3 and 6 month follow-up. RESULTS: Of the 111 patients studied, 82 (68%) had early ST-segment resolution and 29 (32%) did not. Contractility disturbances of infarct related ventricular wall, evaluated by EF and WMI, were significantly higher in the group of patients without early ST-segment resolution immediately after primary PTCA. EF and WMI improved significantly after 3 and 6 months in the group of patients with improvement was insignificant ST-segment elevation resolution, while in the group without ST-segment resolution. CONCLUSIONS: 1. Presence of early ST segment elevation resolution after angiographically successful primary PTCA identifies patients who are more likely to benefit from the early restoration of flow in the infarct related artery. 2. TIMI measures greatly overestimate the success of primary PTCA; they only assess vessel patency, not myocardial cellular perfusion. 3. "Electrocardiographic reperfusion" provides a real-time physiologic marker of cellular perfusion and is a significant predictor of LV contractility recovery--more useful than angiographic reperfusion. 4. ST-segment monitoring is a reliable, non-invasive and inexpensive method to evaluate myocardial perfusion.

Adult↗
PubMed1978

Changes in left ventricular segmental wall motion following randomization to medicine or surgery in patients with unstable angina.

Twenty-six patients with unstable angina pectoris had biplane left ventricular (LV) angiograms and coronary arteriograms (CAGs) initially and at a median of 1 year following randomization to medical (15 patients) or surgical 11 patients) therapy. Left ventricular segmental wall motion was analyzed by a digital computer yielding segmental ejection fraction for 10 zones along the LV perimeter. Baseline and follow-up CAGs were analyzed simultaneously by one observer, and changes in LV segmental coronary perfusion were estimated. Left ventricular angiograms were analyzed separately from CAGs and independently of knowledge of changes in estimated segmental coronary perfusion. Left ventricular segmental wall motion was more frequently improved in surgical patients than in medical patients. Furthermore, in surgical patients there was a significant correlation between changes in LV segmental wall motion and perfusion to LV segments supplied by the left anterior descending coronary artery, whereas no such correlation for any segment was found in the medical group. Thus, this prospective randomized study suggests that, in patients with unstable angina, coronary revascularization may significantly improve LV segmental wall motion compared to medically treated patients. In the surgical group, improvement in LV wall motion relates to improvement in coronary perfusion to the segments supplied by the left anterior descending artery.

Adult↗
PubMed2004

[Whole body versus segmental bioimpedance measurements (BIS) of electrical resistance (Re) and extracellular volume (ECV) for assessment of dry weight in end-stage renal patients treated by hemodialysis].

The precise estimation of the hydration status of the human body has a great meaning in the assessment of dry weight in end-stage renal disease patients treated by hemodialysis. The bioimpedance technique (BIS) is postulated as easy in use and as a non-invasive method in monitoring the size of hydrate space such as total body water (TBW) and extracellular volume (ECV). However, the precision of the method (Whole Body Bioimpedance Technique) has been questioned in several research papers. One of the problems lies in fluid transfer from peripheral spaces (limbs) to the central space (trunk) while changing the position of the body (orthostatic effect). This phenomena can be eliminated using segmental bioimpedance technique (4200 Hydra, Analyzer, Xitron, San Diego, CA, U.S.A.). The purpose of the study was to estimate the changes of electrical resistance (Re) the extracellular volume (ECV) at the time -pre, and -post 10 hemodialysis sessions using whole body bioimpedance technique (WBIS) in comparison to BIS measurements in specific segments of the body; arm (ECVarm), leg (ECVleg), trunk (ECVtrunk). The sum of changes in extracellular volume (ECV) in segments (2ECVarm+ ECVtrunk + 2ECVleg) was 13.26 +/- 1.861 L in comparison to 17.29 +/- 2.07 L (p < 0.01) as measured by WBIS technique at the time before HD. The changes in electrical resistance Re was of 558 +/- 68 W as calculated from the sum of segments versus 560 +/- 70 W (p < 0.05) as measured by WBIS. At the time after hemodialysis the sum of segmental ECV volume measurement was of 11.42 +/- 1.28 L in comparison to 14.84 +/- 1.31 (p < 0.001) from WBIS the whole body technique (WBIS) and changes in electrical resistance Re was of 674 +/- 67 W as calculated from the sum of segments versus 677 +/- 64 (p < 0.05) W respectively. The observed difference between the identical electrical resistance Re as measured by WBIS in comparison to the sum of segment measurements and important difference between ECV volume as measured by WBIS versus sum of segment ECV measurements can be partly explain by non-cylindric nature of human body composition. However, the segmental bio-impedance technique is a method which gives us more accurate data about the extracellular volume taken from each segment in the hemodialysis patient but the accuracy of trunk water assessment is still a problem.

Body Composition↗
PubMed2005

[The changes of electrocardiogram and impact of early invasive strategy in patients with acute coronary syndromes without ST-segment elevation].

OBJECTIVE: To investigate the changes of electrocardiogram (ECG) and impact of early invasive strategy in patients with acute coronary syndrome (ACS) without ST-segment elevation. METHODS: Five hundred and forty-five consecutive ACS patients without ST-segment elevation were randomly assigned to early conservative treatment group and early invasive treatment group. The combined cardiovascular events, including cardiac death, nonfatal myocardial infarction, nonfatal heart failure, and re-hospitalization due to recurrent ischemia angina, within 30 days and 6 months were analyzed and the effects of varied ECG changes and different intervention strategies on outcomes of patients were evaluated. RESULTS: The incidences of each and combined cardiovascular events were higher in the patients with ST-segment depression than in those without ST-segment depression. ST-segment depression was one of independent predictive factors for an increase in cardiovascular events within 6 months (OR 3.864, 95% CI: 1.668 approximately 9.451, P < 0.001). Early invasive strategy was associated with a lower rate of re-hospitalization due to recurrent ischemia angina within 30 days and a decreased incidence of combined cardiovascular events within 30 days and 6 months in comparison with the early conservative treatment group (all P < 0.05). Subgroup analysis implied that incidences of combined cardiovascular events within 30 days and 6 months decreased significantly only in patients with ST-segment depression treated with early invasive strategy, and no such benefit was seen in the patients without ST-segment depression. CONCLUSION: ST-segment depression is an effective indicator for identifying those patients with non-ST segment elevation ACS most likely to benefit from early invasive strategy. Early invasive strategy markedly decreases the cardiovascular events in ACS patients with ST-segment depression than early conservative strategy.

Acute Disease↗
PubMed1991

Spinal cord mensuration--a comparative study on the spinal cord segments and spinal nerves in Zambian goats.

It has been known that the relative length of spinal cord and its segmental volume in domestic animals has established that the dynamics of spinal cord is directly related with the functions of the limbs and in particular to their feeding habits. Bilateral rostrocaudal measurements of spinal nerves involving their root attachment length, root emergence length, interroot length, segment length and cross sectional area were recorded on the dorsal and ventral surfaces of each segment of the spinal cords of five local healthy Zambian goats. We identified that the brachial and lumbar enlargements have involved identical number of spinal cord segments. Brachial and lumbar enlargements extended from C6 to T1 and L4 to L7. The average length of spinal cord was 59.9 cm and it extended up to caudal end of 5th sacral vertebrae. The root emergence length appeared to decrease gradually from C2 segment, which remained less variable in thoracic and lumbar segments and then receded sharply through sacral segments. The dorsal nerves entered spinal cord over a greater area than ventral because of more spinal rootlets. The greatest segment length lied in mid cervical region and then from lumbar segment it decreased sharply up to the end of sacral segments. It is concluded that these goats have a feeding habit similar to that of cattle rather than resting their forelimbs on the shrubs while nibbling the leaves as recorded in Asian goats. It also confirmed that the shrubs were more drooping along with grasses in the Gwembe Valley of Zambia.

Animals↗
PubMed1991

[Persistent ST segment elevation in anterior wall myocardial infarction: a sign of ventricular dysfunction].

BACKGROUND: Persistent ST segment elevation in anterior myocardial infarction was classically attributed to ventricular aneurysm. This association is now considered controversial. To contribute to the elucidation of the problem, the association of this electrocardiographical finding with left ventricular aneurysm and function was assessed. METHODS: In the catheterization studies of 85 patients with chronic anterior wall myocardial infarction the left ventricular function (ejection fraction) and the possible presence of ventricular aneurysm were investigated. These findings were correlated with the persistence of ST segment elevation. RESULTS: 56 of the 85 patients (66%) had persistent ST segment elevation, and 29 (34%) had isoelectric ST segment. 32 cases of left ventricular aneurysm were detected in the group with elevated ST segment (57%) and none in the group with isoelectric ST segment. The ejection fraction was markedly depressed in the group with elevated ST segment (0.34 +/- 0.13) in contrast with the group with isoelectric ST segment (0.52 +/- 0.11) (p less than 0.001). This abnormality in ventricular function was independent from the presence or absence of aneurysm (ejection fraction 0.34 +/- 0.12 vs 0.35 +/- 0.14). CONCLUSIONS: The persistent ST segment elevation is associated with a greater left ventricular function depression, independently from the presence of aneurysm, which is a common finding and exclusive of the group with persistently elevated ST segment.

Adult↗
PubMed1990

[Validation of trend-supported ST segment analysis of long-term ECG recordings].

Trend recordings of relative ST-segment deviations represent a useful tool for the identification of ischemia-like episodes during Holter monitoring. For the generation of trend recordings beat-to-beat data are filtered. The influence of the time constant of the filter on the sensitivity and the specificity for the detection of ischemia-like ECG changes is unknown, however. Ischemia-like episodes were, therefore, simulated and recorded by a frequency modulated Holter recorder and by a conventional six-channel ECG system. Relative ST-segment deviations were filtered using a time constant of 8, 16, 32 or 64 s, or an arithmetic averaging over 9 s for the generation of ST-segment trends. The magnitude of short-lasting ST-segment deviations was underestimated, when beat-to-beat data were filtered using time constants of greater than or equal to 32 s. The influence of posture-related ECG changes on the ST-segment trends was investigated by recording lead CM5 in 14 consecutive patients in different positions by a conventional ECG system. Four out of the 14 patients developed ST-segment elevations greater than or equal to 0.1 mV during leftsided position. Only in these four patients were ST-segment deviations of similar magnitude recorded during the following Holter monitoring. The posture-related ST-segment changes were characterized by an abrupt onset and an abrupt end, resulting in a box-like shape which enabled their correct identification in the ST-segment trend analysis. In order to determine the relative frequency of posture-related ST-segment changes, 35 patients with coronary artery disease (CAD) and 35 patients without underwent Holter monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1990

[Significance of inferior ST segment changes in acute anterior myocardial infarction--relationship between the distribution of left anterior descending artery and concomitant ischemia of the inferior wall].

The significance of inferior ST segment changes was studied in 23 patients with acute anterior myocardial infarction by the distribution of the left anterior descending artery (LAD) after percutaneous transluminal coronary recanalization. In 9 patients (Group A) LAD supplied the anterior wall of the left ventricle up to or including the apex but did not reach the inferior wall; in 8 patients (Group B) it continued beyond the apex onto the inferior wall of the left ventricle with well developed collateral circulation; in 6 patients (Group C) it continued beyond the apex onto the inferior wall of the left ventricle with less-developed or no collateral circulation. Thallium-201 scintigraphy and contrast left ventriculography showed that inferior myocardial ischemia was significantly more prominent in Group C than Group A. These results were consistent with coronary anatomy. Inferior ST segment was significantly more depressed in Group A with no concomitant inferior wall ischemia, than in Group C with concomitant inferior wall ischemia (maximal inferior ST segment change: -1.7 +/- 1.1; 0.8 +/- 1.7 mm, respectively; p less than 0.02). In Group A inferior ST segment was depressed in all 6 patients with lateral ST segment elevation, but it was depressed in only one of 3 patients with no lateral ST segment change. Lateral ST segment elevation tended to cause inferior ST segment depression. This study indicates that the inferior ST segment changes in patients with acute anterior myocardial infarction depend on concomitant ischemia of the inferior wall of the left ventricle by the distribution of LAD and the lateral ST segment changes.

Adult↗
PubMed1987

Opsin accumulation in photoreceptor inner segment plasma membranes of dystrophic RCS rats.

Opsin localization in photoreceptor plasma membrane was studied in 10- to 30-day-old dystrophic RCS rats. Preembedding cytochemical procedures with antiopsin antibodies and electron microscopy were employed. In the second postnatal week, opsin was sequestered to the outer segment plasma membrane in affected rat retinas. This distribution resembled that observed in the photoreceptors of normal rats at this age. As unphagocytosed debris accumulated in the subretinal space, the outer segments degenerated, and the distribution of opsin in the plasma membrane changed. Opsin reappeared in the inner segment plasma membrane as the outer segments were lost. Loss of the regionalized distribution of opsin was not associated with visible ultrastructural changes in the inner segments or connecting cilium. Severely damaged cells invariably were labeled on their inner segments at high density. Thus, the presence of an outer segment was correlated with the clearance of opsin from the inner segment, while damage to the outer segment was followed by reappearance of opsin in the inner segment plasma membrane.

Animals↗
PubMed1988

The human T-cell V gamma gene locus: cloning of new segments and study of V gamma rearrangements in neoplastic T and B cells.

The authors have analyzed the involvement of V gamma and J gamma segments in TRG gamma rearrangement from a series of 40 acute lymphoblastic leukemia (ALL), including 25 T- and 15 B-lineage cases, in which TRG gamma are rearranged. Sixty-five rearranged alleles were studied. The authors first describe the cloning and sequencing of two variable segments, V gamma 11 and psi V gamma 12, which rearrange in T- and B-neoplastic cells. To date three subgroups of translatable V gamma segments have been described. The authors show that V gamma 11 is the unique member of a new fourth V gamma subgroup that also rearranges in normal polyclonal T cells and that psi V gamma 12 is located at 5-kilobase (kb) downstream to V gamma 11. As shown by DNA sequence analysis, V gamma 11 shares a 60% homology with V gamma 10 (third subgroup) and a 50% homology with V gamma 9 (second subgroup) but no appreciable homology with the V gamma segments from the first family. In contrast to psi V gamma 12, V gamma 11 is translatable. In this paper the authors have also attempted to determine which V gamma segments were rearranged in the ALL cases by hybridization with a J gamma probe and genomic probes specific of the four subgroups. In the 54 instances in which the rearrangement was consistent with J gamma 1 or J gamma 2 involvement, the authors have identified the corresponding V gamma segments and have not found any other rearrangements suggestive of the existence of further V regions. The V gamma segments, belonging to the first subgroup, were the most frequently used (41 alleles). V gamma 9, V gamma 10, V gamma 11, and psi V gamma 12 were found rearranged in cases 3, 4, 5, and 1, respectively. No cases using the pseudo psi V gamma 1, psi V gamma 5, and psi V gamma 6 segments were found. Pseudo V gamma segments were not found rearranged in T cells, while V gamma 2 and V gamma 4, segments are frequently used. In contrast to the V gamma I gene rearrangement, the involvement of the V gamma II, V gamma III, and V gamma IV subgroups was most frequently observed in T-ALL with stage II differentiation (CD7+, CD4+, and/or CD8+, CD3-), than in those with stage I (CD7+, CD4-, CD8-, CD3-), than in those with stage I (CD7+, CD4-, CD8-, CD3-) and stage III (CD7+, CD4+/-CD8+/-CD3+).(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

[Quantitative segmental analysis of wall function of the right ventricle in probands with healthy hearts].

To investigate and determine the local wall motion of normal right ventricles, biplane angiograms from 14 normal subjects were analyzed. In all patients, organic heart disease was excluded by angiography and right heart catheterization under exercise. Using a radial model, segmental systolic area shortening was determined for the anterior, anteroapical and inferior segment in the RAO-projection and the inferior, anteroapical and anterior (free wall) segment in the LAO-projection. The highest segmental shortening was found for the anterior wall in the RAO-projection (45.6 +/- 7.8%) and for the free wall in the LAO-projection with 42.7 +/- 11.3% (RAO: anteroapical 28.1 +/- 6.3%; inferior: 26.5 +/- 7.8%. LAO: anteroapical: 34.7 +/- 18.8%; inferior: 30.6 +/- 21.6%). Corresponding to these different segment shortenings, right ventricular contraction seems to have a disharmonic pattern in comparison to the left ventricle. Normal local wall motion of segmental area shortening was predicted by the means-2SD (95.5%) confidence interval. The confidence interval of the inferior (-12.6%) and anteroapical (-2.9%) segment in the LAO-projection was poor compared to the other segments (RAO: anterior 30.0%; anteroapical 15.5%; inferior: 10.9%; LAO: free wall: 20.1%). For the LAO-inferior and LAO-anteroapical segment, even akinesia was within the 95.5% confidence interval. In conclusion, quantification of local wall motion seems possible with reasonable confidence for RAO segments and the free wall in the LAO-projection only.

Aged↗
PubMed1986

Disruption of segmentation in a short germ insect embryo. I. The location of abnormalities induced by heat shock.

The effect of heat shock (15 min at 48 degrees C) on segmentation has been investigated in the short germ embryo of the locust (Schistocerca gregaria). Prior to formation of the germ anlage and at the disc stage heat shock considerably reduced the survival of eggs but appeared to have little effect upon segmentation. At later stages heat shock had no effect on survival but resulted in disruptions of the segmental pattern. The location of abnormal segments depended upon the stage at heat shock and the number affected depended on its severity. A constant number of normal segments developed between the last segment visible at the time of heat shock and the first abnormal segment. These results are similar to the disruptions observed in amphibian somites following heat shock. However, different parts of the segment pattern varied in their response; the head segments were very rarely affected, and disrupted regions rarely started in the middle abdomen (segments A5 and A6). The results are discussed in relation to two models (the clock and wavefront and progress zone models) that have been proposed as an explanation for the specification of the somite pattern in amphibians.

Animals↗
PubMed1976

Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli. 7. Enzymatic joining of the chemically synthesized segments to form a DNA duplex corresponding to the nucleotide sequence 1-26.

Duplex [I], which represents the nucleotide sequence 1-26 of the double-stranded DNA corresponding to the precursor for a tyrosine suppressor tRNA, has been synthesized by the enzymatic joining of five chemically synthesized deoxyribooligonucleotide segments. The synthesis was accomplished in two different ways. In a one-step synthesis, all of the five segments were used together: segments 2, 3, and 5 carried 5'-33P-labeled phosphate groups while segment 4 carried a 32P-phosphate group. An alternative, two-step method involved the joining of 5'-32P-phosphorylated segment 2 to segment 4 (carrying 5'-OH group or 5'-32P- or 33P-labeled phosphate group) in the presence of segment 3 followed by the joining of [5-32P]segment 5 in a second step. The duplex [I]' (segments 2 to 5) thus obtained was phosphorlated at the 5'-ends with polynucleotide kinase and then joined to segment 1 to give duplex [I] quantitatively. The preparative methods described have the desired flexibility for performing the subsequent operations necessary for the total synthesis of the structural gene for the tyrosine suppressor tRNA precursor.

Base Sequence↗
PubMed1994

Biased utilization of DHQ52 and JH4 gene segments in a human Ig transgenic minilocus is independent of antigenic selection.

We have assessed the effect of antigenic selection on human Ig heavy chain D and JH gene segment utilization in mice that contain transgenes composed of 2 VH (psi VH3-105 and VH5-251), 10 D, 6 JH, C mu, and C gamma 1 human gene segments. Human heavy chains using the functional VH5-251 gene segment are expressed in the serum and on the surface of murine B cells. The second VH gene segment (psi VH3-105) is not expressed as a protein but is rearranged and transcribed into mRNA. We previously reported that the functional VH5-251 mu transcripts preferentially used the DHQ52 and JH4 gene segments similar to their use in the human repertoire. Here, we demonstrate that the nonfunctional (psi VH3-105) gene segment shows the same bias in D and JH gene segment utilization. Because transcripts using the pseudo-VH gene segment cannot be subjected to antigenic selection, we conclude that the restricted repertoire observed is Ag independent. Analysis of pseudo VH gene segment recombination products reveals no bias in D gene segment reading frame utilization. Finally, we demonstrate that in the human transgene coding sequence complementarities can affect the recombination site and that D inversion is common.

Animals↗
PubMed1994

Two acquired immunodeficiency syndrome-associated Burkitt's lymphomas produce specific anti-i IgM cold agglutinins using somatically mutated VH4-21 segments.

We analyzed the reactivity and the structure of the VH and VL segments of two IgM monoclonal antibodies (MoAbs) produced by spontaneously in vitro outgrowing cell lines, HBL-2 and HBL-3, established from two acquired immunodeficiency syndrome (AIDS) patients with Epstein-Barr virus (EBV)-negative Burkitt's lymphoma (BL). These B-cell clones were representative of the respective neoplastic parental clones, as determined by immunophenotypic and molecular genetic analysis. The IgM MoAbs were highly specific for the i determinant on red blood cells (cold agglutinins), but bound none of the other eight self and nine foreign antigens (Ags) tested, including those most commonly recognized by natural antibodies or autoantibodies. Structural analysis showed that the IgM MoAb VH segment sequences were 93.5% and 84.2% identical with that of the germline VH4-21 gene, which encodes the vast majority of cold agglutinins that are specific for the i/l carbohydrate Ag and are produced under chronic lymphoproliferative conditions. The HBL-2 MoAb VH4-21 gene segment was juxtaposed with 20P3 and JH6 genes and paired with a V lambda 1 segment, the sequence of which was 95.5% identical to that of the germline Humlv117 gene; the HBL-3 MoAb VH4-21 gene segment was juxtaposed with DXP'1 and JH5 genes and paired with a V lambda 1 segment, the sequence of which was 86.7% identical to that of the germline Humlv1L1 gene. The high degree of conservation of the VH4-21 gene in the human population, the nature of the nucleotide differences in the expressed VH4-21 segments, and the presence of nucleotide substitutions in the HBL-2 and HBL-3 IgM MoAb JH and/or J lambda segments suggested that the MoAb V segments underwent a process of somatic hypermutation. This was formally shown in the HBL-3 MoAb VH segment, by differentially targeted polymerase chain reaction amplification of the HBL-3 MoAb-producing cell genomic DNA. In addition, cloning and sequencing of the genomic DNA from fibroblasts of the same patient whose neoplastic B cells gave rise to the HBL-3 cell line yielded a germline copy of the VH4-21 gene. Thus, the expression of VH4-21 gene products may be involved in a self Ag-driven process of clonal B-cell expansion and selection associated with BL in these AIDS patients.

Agglutinins↗