Genetic linkage analysis identifies new proximal and distal flanking markers for the X-linked agammaglobulinemia gene locus, refining its localization in Xq22

Genetic linkage analysis has been instrumental in mapping thegene for X-linked agammaglobulinemia (XLA) to the proximal longarm of the human X chromosome, to Xq22. Due to the relativerarity of this disease the localization of the gene within Xq22has remained imprecise. We have investigated twenty-nine familiesaffected by XLA and have found no recombinants with the DXS178locus in over 30 informative meioses. DXS178 is now the mostreliable and informative locus for use in pre-natal diagnosisand carrier detection of XLA. In addition, we have identifiednew closely linked proximal and distal flanking markers forXLA, DXS442 and DXS101, respectively. These loci are separatedby 2cM, considerably reducing the extent of DNA within whichthe XLA locus can be contained. This will open up the way formore directed positional cloning efforts for the isolation ofthe XLA gene.     

Molecular characterization and determination of the coding capacity of the genome of equine herpesvirus type 2 between the genome coordinates 0.235 and 0.258 (theEcoRI DNA fragment N; 4.2 kbp)

The complete DNA nucleotide sequence of theEcoRI DNA fragment N (0.235 to 0.258 viral map units) of equine herpes virus type 2 (EHV-2) strain T400/3 was determined. This DNA fragment comprises 4237 bp with a base composition of 55.23% G+C and 44.77% A+T. Nineteen open reading frames (ORFs) of 50-287 amino acid (aa) residues were detected. ORF number 10 is located between the nucleotide position 2220 and 2756 coding for a protein of 179 amino acid residues. This protein shows significant homology to the cytokine synthesis inhibitory factor (CSIF; interleukin 10) of human (76.4%) and mouse (68.5%), and to the Epstein-Barr virus (EBV) protein BCRF1 (70.6%). The existence of an interleukin 10 (IL-10) analogous gene within the genome of the EHV-2 was confirmed by screening the genome of nine EHV-2 strains using specific oligonucleotide primers corresponding to the 5 and 3 region of this particular gene by polymerase chain reaction. In all experiments an 870 bp DNA product was amplified. The specifity of the amplified DNA fragments obtained from individual EHV-2 strains was confirmed by DNA-DNA hybridization experiments. The DNA sequence analysis of the amplified DNA products of the EHV-2 strain LK was carried out. This analysis revealed the identity of the corresponding IL-10 gene (540 bp) of this strain to the IL-10 gene of EHV-2 strain T400/3. The presented data indicate that the EHV-2 genome harbors a viral interleukin 10-like gene. This is further evidence that the IL-10 gene can be present in the genomes of members of the Herpesviridae family.     

The early phase of experimental acute renal failure

Experiments were conducted to establish whether diminished solute reabsorption in the loop of Henle during acute renal failure could explain the loss of urinary concentration and participate in generating a tubuloglomerular feedback-mediated reduction in filtration rate. The electrolyte content of the fluid in the ascending limb of the loop of Henle was determined in situ by monitoring its electrical conductivity after propulsion into the distal tubule with a sudden burst perfusion. The value of the minimum electrolyte concentration decreased exponentially with increasing equilibration time, reaching a steady-state value equivalent to 27±9 mM NaCl in normal kidneys, 34±15 mM in mercuric chloride kidneys and 53±22 mM following ischaemia. A mathematical model was derived to describe the process of sodium chloride dilution from which it was possible to calculate both the permeability and transport velocity of the cortical thick ascending limb. In the normal kidney, the transport velocity was calculated to be 4.65±0.92 ·10^–5 cm/s, a value not significantly different from that of the mercuric chloride or ischaemic kidneys, and the estimated permeability was 1.13±0.52·10^–5 cm/s, not different from that of the mercuric chloride kidneys but significantly lower than that calculated for the ischaemic kidneys. It is concluded that for the more severely damaged ischaemic model, the loss of urinary concentrating ability was accompanied by a reduction in diluting ability of the ascending limb of the short loop of Henle, which appears to be due, at least in part, to an elevation of the passive permeability to sodium chloride in this segment.     

On the peripheral bladder control system of the dog and urodynamics:In vivo characterisation and hybrid computer simulation

A quantitative model of the peripheral bladder control system of the dog is developed. This model is based on the experimental characterisation of the detrusor muscle and the urethra in 25 female dogs. Intravesical pressure, urinary flow and bladder volume were simultaneously recorded during electrical bladder stimulation, and, from these data, a dynamic model of the bladder control system has been deduced. A general equation for predicting urinary flow patterns is developed, and the hybrid computer EAI-690 is used to simulate the evacuation of the bladder. The effect of different parameters of the system on the micturition pattern is investigated in detail. This work may have interesting clinical applications: for example, in the development of adequate techniques for the evacuation of the paraplegic bladder. Also, the experimental procedures elaborated in this study could be applied in the diagnosis of bladder function and urethral obstruction. Indeed, we have been able to characterise the detrusor muscle and the urethra independently using clinically accessible variables.     

Breakpoint clusters of the PML gene in acute promyelocytic leukemia: Primary structure of the reciprocal products of the PML-RARA gene in a patient with t(15;17)

DNA studies of the translocation t(15;17) in acute promyelocytic leukemia (APL) have shown that the retinoic acid receptor alpha (RARA) gene on chromosome 17 is juxtaposed to the promyelocytic leukemia (PML) gene on chromosome 15. The PML breakpoints have been mapped to 3 clusters: bcr1, bcr2, and bcr3. We have examined the PML breakpoint distribution in a series of 33 Chinese patients with APL Twenty-two patients fell within bcr1, 2 within bcr2, and 9 within bcr3. The primary structure of the reciprocal chromosome translocation joints of one patient and that of their normal counterparts have been determined and compared to those of 2 previously reported cases. These studies revealed possible topoisomerase II cleavage sites close to the breakpoints and suggested implications of DNA attachment sites to nuclear matrix. We propose that these features are relevant to the process of illegitimate recombination generating the translocation. © 1993 Wiley-Liss, Inc.     

Functional magnetic resonance imaging evidence for binocular interactions in human visual cortex

Using functional magnetic resonance imaging (fMRI), we explored the binocular interactions occurring when subjects viewed dichoptically presented checkerboard stimuli. A flickering radial checkerboard was presented to each eye of the subject, while T2*-weighted images were acquired over the visual cortex with gradient-echo, echoplanar sequences. We compared responses in striate and extrastriate visual cortex under four conditions: both eyes were stimulated at the same time (binocular condition), each eye was stimulated in alternation (monocular condition) or first the one eye then the other eye was stimulated (left eye first - right eye trailing, or vice versa). The results indicate that only the striate area, in and near the calcarine fissure, shows significant differences for these stimulation conditions. These differences are not evident in more remote extrastriate or associational visual areas, although the BOLD response in the stimulation-rest comparison was robust. These results suggest that the effect could be related to inhibitory interactions across ocular dominance columns in striate visual cortex.     

Neuronal apoptosis in the dentate gyrus in humans with subarachnoid hemorrhage and cerebral hypoxia

Apoptosis of dentate granule cells is a typical feature of several animal models of disease. In 20 autopsy cases of subarachnoid hemorrhage (SAH) and global cerebral hypoxia caused by protracted shock or respiratory failure, we evaluated by light microscopy and in situ tailing whether this pattern of neuronal damage also occurs in humans. In subarachnoid hemorrhage, 4.0/mm2 (0-13.0/mm2) apoptotic neurons were observed in the dentate gyrus, in cerebral hypoxia 3.6/mm2 (0-19.9/mm2) (p>0.05), and in 10 aged-matched control cases dying rapidly from non-neurological diseases 0/mm2 (0-0/mm2) (median [range]) (p<0.001 versus SAH and hypoxia). Neuronal apoptosis in the dentate gyrus was most frequent, when death occurred later than 24 hours and less than 11 days after disease onset. Neuronal damage in the hippocampus was always necrotic. It was more severe in hypoxia than in SAH (median neuronal damage score 3 [range: 0-3] versus 0 [0-3], p<0.001). Apoptosis appears to be the predominant mechanism of death in dentate granule cells irrespective of the underlying disease, whereas neuronal death in the hippocampus generally is of necrotic morphology.     

Role of ventricular assist devices in the German heart allocation system

The Eurotransplant (ET) allocation algorithm, newly implemented in 2000, gives priority for heart transplantation (HTx) to patients with high urgency (HU) status, but now this status is rescinded upon ventricular assist device (VAD) implantation and only regained if severe complications occur during mechanical circulatory support (MCS). We studied the effects of this change on the patients in our institute who were waiting for HTx with MCS. The median duration of MCS until HTx in adult patients gradually increased from 3.1 months in 1994, reaching a peak of 16.7 months in 2000, and then gradually decreased to 6.0 months in 2003. Among the patients with VAD implantation as a bridge to HTx, two patients were on MCS for more than 1 year (the longest duration of MCS being 1.6 years) at the end of 1999, and this figure increased to nine patients and a maximum MCS duration of 3.7 years at the end of 2003. These data imply that the patients in whom a complication occurred in the early phase of MCS and who had overcome this complication underwent HTx early with HU status, and those who were stable during MCS waited a long time for HTx. Furthermore, the number of patients in the latter group is increasing. The new allocation algorithm imposes on patients with MCS waiting for HTx who are relatively young and free from complications and serious coexisting disease, very long-term MCS without an end to VAD bridging, which is almost equivalent to destination therapy. Part of this paper was presented at the 42nd JSAO Conference (Tokyo, October 5–7, 2004)