Human centromeric DNAs.

Human centromeres have been extensively studied over the past two decades. Consequently, more is known of centromere structure and organization in humans than in any other higher eukaryote species. Recent advances in the construction of a human (or mammalian) artificial chromosome have fostered increased interest in determining the structure and function of fully functional human centromeres. Here, we present an overview of currently identified human centromeric repetitive DNA families: their discoveries, molecular characterization, and organization with respect to other centromeric repetitive DNA families. A brief examination of some functional based studies is also included.

Brodifacoum rodenticide ingestion in a patient with shigellosis.

Factitious disorders are characterized by the intentional feigning or induction of signs and/or symptoms in order to assume the sick role. The spectrum of diseases and symptoms simulated is extensive. Although some patients may seek only the gratifications of the sick role, typically patients seek health care for their afflictions. We report the case of a woman with a history of numerous unexplainable illnesses and laboratory findings who had shigellosis. On routine evaluation, a severe prothrombin coagulopathy was discovered and later determined to be caused by brodifacoum, a "superwarfarin" drug found in potent rodenticides. The patient was successfully treated with daily vitamin K. She continued to deny intentional or accidental ingestion but did consent to psychiatric treatment.

Independent segregation of von Hippel-Lindau disease and cerebral cavernomas.

A probable diagnosis of von Hippel-Lindau disease was made in a two generation family in which the proband had a phaeochromocytoma, renal cysts, and multiple cerebral cavernomas. His sister had multiple similar cerebral vascular lesions and his father died from renal carcinoma aged 42. Although the family did not satisfy the conventional diagnostic criteria for von Hippel-Lindau disease, an underlying germline mutation in the von Hippel-Lindau disease tumour suppressor gene was identified in the proband. Molecular genetic analysis not only confirmed the putative diagnosis of the disease in the proband but also showed that the cerebral vascular lesions segregated independently from the von Hippel-Lindau disease mutation. This report exemplifies how molecular genetic investigations can enhance the diagnosis and management of families with suspected von Hippel-Lindau disease, particularly when the manifestations, as in this family, are not typical.

The accident and emergency department as a single portal of entry for the reassessment of all trauma patients transferred to specialist units.

127 patients who were transferred to a regional referral centre for specialist treatment within 48 h of serious injury were reassessed on arrival in the receiving accident and emergency department by a trauma team. 80 transferred patients (63%) required intervention in the accident and emergency department to complete assessment or resuscitation. In view of the well recognised difficulties in managing patients with multiple trauma and the possibility that initially occult injuries may become clinically significant during transport, transferred trauma patients should be reassessed in the accident and emergency department of the receiving hospital by a trauma team consisting of senior medical staff experienced in all aspects of trauma care.

Localization of DNA sequences required for human centromere function through an analysis of rearranged Y chromosomes.

We have localized the DNA sequences required for mitotic centromere function on the human Y chromosome. Analysis of 33 rearranged Y chromosomes allowed the centromere to be placed in interval 8 of a 24-interval deletion map. Although this interval is polymorphic in size, it can be as small as approximately 500kb. It contains alphoid satellite DNA and approximately 300kb of adjacent Yp sequences. Chromosomes with rearrangements in this region were analysed in detail. Two translocation chromosomes and one monocentric isochromosome had breakpoints within the alphoid array. Of 12 suppressed Y centromeres on translocation chromosomes and dicentric isochromosomes that were also analysed two showed deletions one of which only removed alphoid DNA. These results indicate that alphoid DNA is a functional part of the Y chromosome centromere.

Transatlantic perspectives of trauma systems.

The need for centralized management of acute trauma was evaluated in a 1-year prospective study in Northern Ireland. All patients with an Injury Severity Score > 15 who reached hospital alive were included. The sample population was approximately 1 million people. A total of 239 patients entered the study, of whom 74 died. An audit panel considered that 3-15 per cent of deaths were preventable. There was no significant difference in the preventable mortality rate between any hospital or groups of hospitals. There was a high level of consultant involvement, especially in small hospitals. A system in which patients with acute trauma bypass the nearest hospital to reach a trauma centre may be neither beneficial nor cost-effective in Northern Ireland. Upgrading of the present system with stabilization of the patient and emergency surgery at the nearest hospital before transfer is recommended.

The major centromeric array of alphoid satellite DNA on the human Y chromosome is non-palindromic.

We have determined the orientation of the major centromeric alphoid array on the human Y chromosome. A PCR assay was used to analyse the vector-insert junctions of seven YAC clones previously positioned on two independent Y chromosomes. The orientation is the same at all 10 positions measured. This suggests that the alphoid array is a simple unidirectional repeat throughout and that human centromere structure thus differs from the palindromic organisation found in Schizosaccharomyces pombe.

Structure of the sequences adjacent to the centromeric alphoid satellite DNA array on the human Y chromosome.

Eighteen yeast artificial chromosome (YAC) clones containing alphoid satellite DNA and adjacent sequences from the human Y chromosome have been identified from three different YAC libraries. Restriction site mapping of the genomic alphoid arrays and the YACs has allowed seven of the alphoid clones to be positioned on the arrays. Three clones extend into flanking sequences. At one edge the alphoid DNA is highly diverged and is flanked by a small block of the 48 base-pair satellite, dispersed moderately repeated sequences and a separate short alphoid array. More distal sequences are Y-specific. At the other edge there is much less divergence and the alphoid DNA is flanked by an Alu sequence and the five base-pair satellite.

Structure of the pericentric long arm region of the human Y chromosome.

We have analysed the sequence organization of the DNA in the pericentric region of the long arm of the human Y chromosome. The structures of one cosmid and three yeast artificial chromosome clones were determined. The region consists of a mosaic of the known 5, 48 and 68 base-pair tandemly repeated sequences and at least five novel repeated sequence families. A long range-map of approximately 3.5 x 10(6) base-pairs of genomic DNA was constructed that placed the clones between about 500 x 10(3) and 850 x 10(3) base-pairs from the long arm edge of the centromeric alphoid DNA array.

Improving the care of patients with major trauma in the accident and emergency department.

OBJECTIVE: To determine whether improvement in the care of victims of major trauma could be made by using the revised trauma score as a triage tool to help junior accident and emergency doctors rapidly identify seriously injured patients and thereby call a senior accident and emergency specialist to supervise their resuscitation. DESIGN: Comparison of results of audit of management of all seriously injured patients before and after these measures were introduced. SETTING: Accident and emergency department in an urban hospital. PATIENTS: All seriously injured patients (injury severity score greater than 15) admitted to the department six months before and one year after introduction of the measures. RESULTS: Management errors were reduced from 58% (21/36) to 30% (16/54) (p less than 0.01). Correct treatment rather than improvement in diagnosis or investigation accounted for almost all the improvement. CONCLUSIONS: The management of seriously injured patients in the accident and emergency department can be improved by introducing two simple measures: using the revised trauma score as a triage tool to help junior doctors in the accident and emergency department rapidly identify seriously injured patients, and calling a senior accident and emergency specialist to supervise the resuscitation of all seriously injured patients. IMPLICATIONS: Care of patients in accident and emergency departments can be improved considerably at no additional expense by introducing two simple measures.

Structural instability of human tandemly repeated DNA sequences cloned in yeast artificial chromosome vectors.

The suitability of yeast artificial chromosome vectors (YACs) for cloning human Y chromosome tandemly repeated DNA sequences has been investigated. Clones containing DYZ3 or DYZ5 sequences were found in libraries at about the frequency anticipated on the basis of their abundance in the genome, but clones containing DYZ1 sequences were under-represented and the three clones examined contained junctions between DYZ1 and DYZ2. One DYZ3 clone was quite stable and had a long-range structure corresponding to genomic DNA. All other clones had long-range structures which either did not correspond to genomic DNA, or were too unstable to allow a simple comparison. The effects of the transformation process and host genotype on YAC structural stability were investigated. Gross structural rearrangements were often associated with re-transformation of yeast by a YAC. rad1-deficient yeast strains showed levels of instability similar to wild-type for all YAC clones tested. In rad52-deficient strains, DYZ5 containing YACs were as unstable as in the wild-type host, but DYZ1/DYZ2 or DYZ3 containing YACs were more stable. Thus the use of rad52 hosts for future library construction is recommended, but some sequences will still be unstable.

Active transport of salicylate by rat jejunum.

Using an improved segmented flow technique the uptake of salicylate in low concentration (1-3 mM) by rat jejunum is found to be steady for ca. 30 min, and is proportional to lumen concentration. At higher lumen concentrations (6-8 mM) the rate of uptake falls from the beginning to very low levels. At low lumen concentrations the tissue fluid concentration rises to approximately three times the lumen concentration without significant effect on the uptake rate. This rise is an exponential function of the net water transport across the intestinal wall. The rate constant is of the same order of magnitude as those found earlier for equilibration of tissue fluid with glucose and wash-out of protein from the tissue fluid. The uptake of salicylate is inhibited irreversibly by 2,4-dinitrophenol (2-4 x 10(-5) M).