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D David

Publications and source records attributed to D David.

At least 91 records · Page 5Linked to original sources
PubMed1995

Analysis of human VH gene repertoire expression in peripheral CD19+ B cells.

Using CD19 B-cell selection and polymerase chain reaction-amplified cDNA libraries, we analyzed the peripheral immunoglobulin heavy chain variable repertoire of three healthy adult donors. Here we report that most of the CD19+ circulating B cells expressed unmutated VH-D-JH rearrangements. By specific VH family hybridization, we show that VH gene family utilization in the periphery roughly corresponds to the complexity of these families in the germline and appears to be relatively constant among the analyzed subjects. However, sequence data of clones picked at random from one IgM cDNA library reveals that in spite of this "random" utilization, the VH gene expression in naive circulating B cells is highly biased towards the expression of a limited set of VH genes. As previously reported by others, this restricted mechanism is also found for the D and JH segments.

Adult↗
PubMed1995

Characterization of a splicing mutation in the factor VIII gene at the RNA level.

Haemophilia A is an X-linked bleeding disorder caused by mutations in the coagulation factor VIII (FVIII) gene. The identification and characterization of naturally occurring disease-producing mutations allows the recognition of new mechanisms of pathogenesis in haemophilia A. Analysis of the illegitimately transcribed FVIII mRNA in a severely affected patient has revealed that the A-->G transition at position -2 of the acceptor splice site of intron 4 results in the skipping of exon 5 in 90% of the processed pre-mRNA. Another minor mRNA species arising from the skipping of exons 4 and 5 has also been observed. The skipping of exon 5 predicts the removal of the corresponding 13 amino acids from the A1 domain of FVIII. A novel missense mutation, C329S, in exon 8 of FVIII gene has been identified in another patient.

Base Sequence↗
PubMed1995

Foot and mouth disease virus replication in bovine skin Langerhans cells under in vitro conditions detected by RT-PCR.

The replication of foot and mouth disease virus (FMDV) was studied in isolated bovine skin Langerhans cells (LC), in keratinocytes from epidermal cell suspension, and in migrating LC obtained from cultured bovine epidermal sheets in vitro. Viral RNA replication in infected cells was determined by the reverse transcriptase-polymerase chain reaction (RT-PCR) of the negative FMDV RNA strand and by the plaque forming assay of FMDV. It was established that bovine skin LC, keratinocytes, and migratory bovine LC infected with FMDV strain 01 Geshur supported virus replication. This RT-PCR method to detect the negative strand of FMDV RNA in migratory bovine skin LC may be useful for determining FMD virus replication in tissue cells.

Amino Acid Sequence↗
PubMed1995

Variable region light chain genes encoding human antibodies to HIV-1.

In previous work, it was found that the heavy chain variable gene (VH) repertoire of human antibodies to HIV is markedly skewed and that the gp120 molecule is a ligand for VH3 gene products. Here, we have analysed the light chain (L-chain) variable region genes (VL) expressed by a panel of human monoclonal antibodies derived from an immunized volunteer, an AIDS patient and seropositive asymptomatic donors, and specific for HIV-1 p25, gp41 and gp120 proteins. We found that, in contrast to VH gene-family use, the VL repertoire does not exhibit a family-bias. We noticed however, a tendency to the use of VL genes that map to the downstream portion of the kappa locus. The VL genes expressed have mutated at lower rates than the corresponding VH genes and show no clustering of the replacement mutations in the hypervariable regions. We also found that the third hypervariable regions (CDR3) of the L-chains have undergone a marked diversification, with addition of untemplated nucleotides, frequent truncation at the 3' end of the VLs and somatic mutation. These molecular events result in a length heterogeneity of the CDR3s and an apparently positive selection of specific highly reactive amino acids. We conclude that the specificity of, at least some of the anti-HIV antibodies, is dictated by the L-chain CDR3 regions which bear the imprints of antigenic selection.

Amino Acid Sequence↗
PubMed1995

Sleep disturbance and its relationship to psychiatric morbidity after Hurricane Andrew.

OBJECTIVE: Sleep disturbance is an important dimension of posttraumatic stress disorder (PTSD), but most of the limited available data were obtained years after the original traumatic event. This study provides information on sleep disturbance and its relationship to posttraumatic morbidity from evaluations done within a year after the trauma. METHOD: Sleep and psychiatric symptoms of 54 victims (12 men and 42 women) of Hurricane Andrew who had no psychiatric illness in the 6 months before the hurricane were evaluated. A subset of hurricane victims with active psychiatric morbidity (N = 10) and nine comparison subjects who were unaffected by the hurricane were examined in a sleep laboratory. RESULTS: A broad range of sleep-related complaints were rated as being greater after the hurricane, and psychiatric morbidity (which was most commonly PTSD, followed by depression) had a significant effect on most of the subjective sleep measures. In addition, subjects with active morbidity endorsed greater frequencies of "bad dreams" and general sleep disturbances before the hurricane. Polysomnographic results for the hurricane victims revealed a greater number of arousals and entries into stage 1 sleep. REM density correlated positively with both the PTSD symptom of reexperiencing trauma and global distress. CONCLUSIONS: Subjects affected by Hurricane Andrew reported sleep disturbances, particularly those subjects with psychiatric morbidity. Tendencies to experience bad dreams and interrupted sleep before a trauma appear to mark vulnerability to posttraumatic morbidity. Results of sleep laboratory evaluations suggested brief shifts toward higher arousal levels during sleep for PTSD subjects and a relationship of REM phasic activity and symptom severity.

Adult↗
PubMed1995

Factors affecting non-attendance in an ophthalmic outpatient department.

The object of the study was to establish the non-attendance rates in an ophthalmic outpatient department and any non-attendance patterns that may be useful in managing future outpatient resources. A detailed retrospective survey of monthly non-attendance rates was carried out in the outpatient department of a dedicated eye hospital over a 1 year period looking at differences in non-attendance between morning and afternoon clinics and new and review patients. A total of 43,004 scheduled outpatient appointments predominantly from the suburban population of the Merseyside region were made at St Paul's Eye Hospital from the 1 February 1990 to 31 January 1991. Five thousand four hundred and twenty-four appointments were missed giving an overall non-attendance rate of 12.6%. Non-attendance rates for morning and afternoon appointments were 12.0% and 13.0%, respectively: and for new and review patients, 11.9% and 12.8%, respectively. Logistic regression analysis showed that patients with afternoon appointments were on average 1.10 times more likely to non-attend than morning patients (P = 0.002), and that review patients were 1.09 times more likely to non-attend than new patients (P = 0.04). In order to maximize outpatient department efficiency, a reduction in non-attendance is essential. Establishing patterns for non-attendance provides us with a framework around which we can plan measures to compensate for outpatient non-attendance.

England↗
PubMed1995

Panic-phobic patients and developmental trauma.

BACKGROUND: Several studies suggest high rates of developmental trauma among adult anxiety disorder patients. We attempted to replicate these findings in patients with panic disorder, agoraphobia, and/or social phobia in comparison with a nonclinical population and to evaluate possible relationship of traumas and phobic subtypes. METHOD: Fifty-one patients with panic disorder with agoraphobia and/or social phobia were assessed for lifetime diagnoses using interviews and rating scales and for developmental trauma by the Life Experience Questionnaire (LEQ). Fifty-one demographically similar nonclinical subjects completed a questionnaire that included the LEQ and screening questions for lifetime psychopathology. RESULTS: Childhood trauma was reported by 63% (N = 32) of the patients (vs. 35% or 18 of comparison subjects and 24% or 9 of subjects negative for lifetime psychopathology; chi 2 = 7.7, df = 1, p < .01). Sexual and/or physical abuse histories (and not separation and/or loss) were significantly increased in the patient group and were most specifically associated with social phobia. CONCLUSION: We find a similar, increased rate of childhood trauma as has been reported in previous studies of anxiety disorder patients. In our findings, this most specifically represents an association of social phobia and sexual/physical abuse histories.

Adolescent↗
PubMed1994

Analysis of the essential sequences of the factor VIII gene in twelve haemophilia A patients by single-stranded conformation polymorphism.

We report the analysis by single-stranded conformation polymorphism of the essential sequences of the factor VIII(FVIII) gene (total length about 14 kb) including the entire coding sequence, flanking intronic sequences and the putative regulatory sequences 5' to the gene, in twelve unselected haemophilia A patients of Portuguese origin. Direct sequencing of the fragments with an altered migration pattern led to the identification of the disease-producing mutations in five patients. Three of these mutations, namely a 1 bp insertion in a motif of eight consecutive A residues at codon 1439 (FVIIIPorto3); a C to T transition at codon 1966 (Arg-->Stop), found in an inhibitor-positive patient (FVIIIMontijo); and a G to A transition at codon 479 (Gly-->Arg; FVIIIPorto1), have been reported in other ethnic groups. The two novel mutations are the substitution of AG by GG at the 3' end of intron 4 (FVIIILisboa1) destroying the invariant splice acceptor sequence, and a G to A transition at codon 1948 resulting in an aspartic acid substitution for glycine (FVIIIPorto2).

Base Sequence↗
PubMed1994

Sleep and duodenal motor activity in patients with severe non-ulcer dyspepsia.

The prevalence of sleep disturbances was studied in patients with severe non-ulcer dyspepsia. It was also considered if the change in sleep pattern was associated with changes in the rhythmic fasting motor activity of the gastrointestinal tract, and if motor events correlate with the patient's symptoms. Motor activity in the duodenum was monitored over a 24 hour period under freely ambulatory conditions in 10 healthy controls and in 10 patients with severe non-ulcer dyspepsia using a transnasally placed catheter with six solid state pressure transducers connected to a digital data logging device. Symptoms and sleep disturbance were assessed by questionnaire and diary. Based on their symptoms, the patients were separated into two groups: those with dyspepsia symptoms only (non-ulcer dyspepsia; n = 5) and those with dyspepsia and additional functional symptoms thought to arise from the lower gastrointestinal tract (non-ulcer dyspepsia+irritable bowel syndrome; n = 5). When compared with either the control or the non-ulcer dyspepsia+irritable bowel syndrome group, non-ulcer dyspepsia patients had a considerably decreased number of migrating motor complexes during the nocturnal period (0.7 v 4.6), a decreased percentage of nocturnal phase I (5.2% v 78.0%), and an increased percentage of the nocturnal period in phase II (94% v 15.4%). Patients with non-ulcer dyspepsia+irritable bowel syndrome were not different from normal controls. Four of the non-ulcer dyspepsia patients and all of the non-ulcer dyspepsia+irritable bowel syndrome patients reported difficulties with sleep. Clusters of high amplitude tonic and phasic activity, not accompanied by subjective reports of discomfort were noted in several patients in both groups during the study. In eight of 10 patients, abdominal pain was reported during normal motor activity, while in one patient, pain correlated with phase III of the migrating motor complex. In contrast with previous reports in patients with irritable bowel syndrome, our findings suggest an abnormality of diurnal rhythmicity--shown in changed sleep and changed rhythmic duodenal motor activity--in patients with chronic abdominal pain thought to arise from the upper gastrointestinal tract.

Abdominal Pain↗
PubMed1994

On small genomes in eukaryotic organisms: molecular karyotypes of two microsporidian species (Protozoa) parasites of vertebrates.

Pulsed field gel electrophoresis (PFGE) was used to separate chromosome-sized DNA from two species of microsporidia of fishes. The molecular karyotype of Glugea atherinae exhibits 16 DNA bands from 420 to 2,700 kb, and that of Spraguea lophii 12 bands from 230 to 980 kb. Until now they represent respectively the largest and the smallest genomes visualized for microsporidia: 19.5 Mb for G. atherinae and 6.2 Mb for S. lophii (the smallest nuclear genome in eukaryotic organism). We have analysed separately five strains of G. atherinae (individual cysts), with this technique. The electrophoretic spectra are the same for these strains, except for the absence of the 2,380-kb band in one case. Therefore, the karyotype seems to be rather well conserved for this species.

Animals↗
PubMed1994

Post-traumatic stress disorder in myocardial infarction patients: prevalence study.

This study examined the prevalence of post-traumatic stress disorder (PTSD) in a sample of 100 Israeli myocardial infarction (MI) patients. Chronic PTSD was diagnosed in 16% of these patients and acute (PTSD) in 9%. The appearance of PTSD following MI was found to be related to the following variables: ethnic background; prior traumatic experiences, including prior MI; and anticipation of disability following MI. Objective measures of MI severity were not related to propensity to develop PTSD. The presence of PTSD correlated with self reports of dysfunction in these MI patients and may account for the majority of failures in rehabilitation.

Adult↗
PubMed1993

Single-strand conformation polymorphism (SSCP) analysis of the molecular pathology of hemophilia B.

In the present study, we report the application of polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis to the screening of seven functionally important factor IX gene (FIX) regions (total length 2.66 kb) in 9 unrelated haemophilia B patients of Portuguese or African origin. In eight of the patients an altered migration pattern of single-stranded DNA was observed. Direct sequencing of the relevant DNA fragments unveiled the following sequence alterations: two novel mutations, namely FIXBarcelos Thr-380-Pro and FIXLousada 9bp insertion at position 31,309 or 31,318; five mutations previously reported in other ethnic groups (FIXPorto Arg-145-His, FIXLuanda Gly-207-Arg, FIXPenafiel Arg-248-Gln, FIXSesimbra Arg-333-Gln, FIXCascais Arg-333-Stop); and a normal variant, G-->T transvertion at position 6,596 in intron 2. We propose hypothetical models for the generation of the 9 bp duplication (FIXLousada). We have performed molecular modeling studies in order to predict the structure of the variant FIX molecules.

Base Sequence↗
PubMed1993

Molecular analysis and genetic mapping of the rhodopsin gene in families with autosomal dominant retinitis pigmentosa.

Eighty-eight patients/families with autosomal dominant retinitis pigmentosa (RP) were screened for rhodopsin mutations. Direct sequencing revealed 13 different mutations in a total of 14 (i.e., 16%) unrelated patients. Five of these mutations (T4K, Q28H, R135G, F220C, and C222R) have not been reported so far. In addition, multipoint linkage analysis was performed on two large families with autosomal dominant RP due to rhodopsin mutations by using five DNA probes from 3q21-q24. No tight linkage was found between the rhodopsin locus (RHO) and D3S47 (theta max = 0.08). By six-point analysis, RHO was localized in the region between D3S21 and D3S47, with a maximum lod score of 13.447 directly at D3S20.

Australia↗
PubMed1993

Myocardial regional blood flow: quantitative measurement by computer analysis of contrast enhanced echocardiographic images.

Quantitation of regional myocardial blood flow constitutes the missing link between the anatomy of coronary obstruction and its physiological effect on regional oxygen supply. Microscopic air bubbles, introduced into the coronary circulation, were shown to produce a transitory enhancement of the myocardial tissue contrast, easily detectable with standard ultrasonic imaging equipment. This study presents a new approach linking the tissue blood flow with the time-dependent changes in the intensity of the ultrasonic reflections produced by the microbubbles. The tissue blood flow is evaluated using the well-known indicator dilution relation, according to which flow equals the ratio between the intravascular fraction of the tissue sample volume and the mean transit time of the contrast agent. We derive these two parameters from the time curves representing the contrast induced variations in the mean videointensity measured in two regions of interest, a reference region in the left ventricular cavity and the region of interest within the myocardial tissue. The intravascular volume fraction is computed as the ratio of the total power of the above two intensity curves, as each of these is assumed to be proportional to the total amount of tracer traversing the corresponding region of interest. The mean transit time is computed using combined time- and frequency-domain processing, involving Fourier deconvolution of the response function of the myocardial tissue sample. This approach was validated in an in vivo model in a series of animal experiments involving left atrial injection of albumin coated air microbubbles (Albunex). Videointensity curves obtained during contrast enhancement of the myocardium were analyzed to provide values of regional myocardial blood flow (in mL/min/100 g) in 45 myocardial regions of interest defined in 7 experiments performed on 4 animals. The values obtained with our approach correlated well (r = 0.77, p < 0.001) with standard reference measurements based on radiolabeled microspheres. The intertechnique variability was found to be smaller than the intersegment variability characterizing our technique. The difference between the mean flow values obtained with microspheres for segments of the entire heart and the mean flow obtained with our technique for all regions of interest ranged between 1 to 19% in the 7 experiments. In its present form, based on left atrial or left ventricular injection of contrast solution, this method may allow, for the first time, quantitative evaluation of myocardial regional blood supply in the cardiac catheterization laboratory or the operation theater.(ABSTRACT TRUNCATED AT 400 WORDS)

Albumins↗