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Biomedical subjects

M Cook

Publications and source records attributed to M Cook.

At least 37 records · Page 2Linked to original sources
PubMed1991

Familial dystonic choreoathetosis with myokymia; a sleep responsive disorder.

A family is presented with paroxysmal dystonic choreoathetosis transmitted as a dominant trait over five generations. The family is unusual in the marked responsiveness of the episodes to short periods of sleep in several members, in the very variable age of onset, and in the association with prominent myokymia in some cases. These overlap features suggest a link between paroxysmal dystonic choreoathetosis and familial paroxysmal ataxia with myokymia.

Adolescent↗
PubMed1991

The branchial Hox code and its implications for gene regulation, patterning of the nervous system and head evolution.

In this study we have examined the expression of murine Hox homeobox containing genes by in situ hybridisation in the branchial region of the head. Genes from the Hox complexes display segmentally restricted domains of expression in the developing hindbrain, which are correlated with similar restricted domains in the neural crest and surface ectoderm of the branchial arches. Comparison of related genes from the different clusters shows that subfamily members are expressed in identical rhombomeres and branchial arches. These patterns suggest a combinatorial system for specifying regional variation in the head, which we refer to as a Hox code. The Hox genes also display dynamic dorso-ventral (D-V) restrictions in the developing neural tube which mirror the timing and spatial distributions of the birth of major classes of neurons in the CNS. Genes in the Hox-2 cluster all have a similar D-V distribution that differs from that of genes from the other Hox clusters, and suggests that members of a subfamily may be used to specify positional values to different subsets of cells at the same axial level. These results are discussed in terms of a system for patterning the branchial regions of the vertebrate head, and evolution of head structures. We have also examined aspects of the transcriptional regulation of Hox-2 genes in transgenic mice using a lacZ reporter gene. We have been able to reconstruct the major pattern of the Hox-2.6 gene on the basis of identical expression of the transgene and the endogenous gene with respect to timing, spatial restrictions and tissue-specific distributions. Deletion analysis has enabled us to identify three regions involved in generating this pattern. Two of these regions have the properties of enhancers which are capable of imposing spatially-restricted domains of expression on heterologous promoters. We have generated similar Hox-lacZ fusions that reconstruct the highly restricted patterns of the Hox-2.1 and Hox-2.8 genes in the developing nervous system, supporting our in situ analysis and the idea of a Hox code. These transgenic experiments are a useful step in examining regulation in the Hox cascade.

Amino Acid Sequence↗
PubMed1991

DNA flow cytometry of large-bowel biopsies showing that adenoma tissue predicts the ultimate nature of the lesions.

Ploidy of neoplastic large-bowel cells in lesions from which biopsies showed only adenoma tissue by histopathologic examination was investigated retrospectively by DNA flow cytometry. Biopsy and resected-specimen blocks gave interpretable ploidy profiles from 83 lesions. The expectation that adenomas will show diploidy in biopsies and that adenocarcinomas will show aneuploidy in biopsies was fulfilled in 80% of the lesions. In addition, four lesions with diploid biopsies were polyps with minimal invasion. Thus, diploidy would have correctly predicted that local resection was adequate treatment for 62 lesions and conversely that cancer resection was the appropriate treatment for 8 lesions, for an overall predictive success rate of 87%. In conjunction with endoscopic, radiologic and other data, DNA flow cytometry of biopsies from apparently benign large-bowel lesions could become a useful addition to therapeutic decision-making.

Adenocarcinoma↗
PubMed1990

A yeast artificial chromosome containing the mouse homeobox cluster Hox-2.

We have isolated two genes, Hox-2.8 and Hox-2.9, from the mouse homeobox cluster Hox-2, located on chromosome 11. A 120-kilobase yeast artificial chromosome (YAC) containing a large region of the murine Hox-2 cluster, including 45 kilobases of sequence upstream of the most 5' gene, was cloned. The DNA sequence of the YAC is unrearranged relative to the genomic map. We have subcloned from the YAC insert a homeobox gene, Hox-2.8, whose homeodolmain is highly related to that of the Drosophila homeotic gene proboscopedia (pb). The expression pattern of Hox-2.8 during embryogenesis extends the trend established by genes from Hox-2.5 to -2.7 of successively anterior domains of expression in the neural tube. We have also subcloned and sequenced from a cosmid the labial (lab)-related Hox-2.9, the most 3' member of the cluster to date. These data lend further support to the idea of a common evolutionary origin of the mouse Hox and Drosophila HOM clusters. The YAC will enable us to construct modified forms of the Hox-2 cluster in yeast and to identify their effect on the phenotype of the animal in transgenic mouse strains.

Amino Acid Sequence↗
PubMed1990

Renal transplantation in infants.

The timing of renal transplantation in infants is controversial. Between 1965 and 1989, 79 transplants in 75 infants less than 2 years old were performed: 23 who were 12 months or younger, 52 who were older than 12 months; 63 donors were living related, 1 was living unrelated, and 15 were cadaver donors; 75 were primary transplants and 4 were retransplants. Infants were considered for transplantation when they were on, or about to begin, dialysis. All had intra-abdominal transplants with arterial anastomosis to the distal aorta. Sixty-four per cent are alive with functioning grafts. The most frequent etiologies of renal failure were hypoplasia (32%) and obstructive uropathy (20%); oxalosis was the etiology in 11%. Since 1983 patient survival has been 95% and 91% at 1 and 5 years; graft survival has been 86% and 73% at 1 and 5 years. For cyclosporine immunosuppressed patients, patient survival is 100% at 1 and 5 years; graft survival is 96% and 82% at 1 and 5 years. There was no difference in outcome between infants who were 12 months or younger versus those who were aged 12 to 24 months; similarly there was no difference between infants and older children. Sixteen (21%) patients died: 5 after operation from coagulopathy (1) and infection (4); and 11 late from postsplenectomy sepsis (4), recurrent oxalosis (3), infection (2), and other causes (2). Routine splenectomy is no longer done. There has not been a death from infection in patients transplanted since 1983. Rejection was the most common cause of graft loss (in 15 patients); other causes included death (with function) (7), recurrent oxalosis (3), and technical complications (3). Overall 52% of patients have not had a rejection episode; mean creatinine level in patients with functioning grafts is 0.8 +/- 0.2 mg/dL. Common postoperative problems include fever, atelectasis, and ileus. At the time of their transplants, the infants were small for age; but with a successful transplant, their growth, head circumference, and development have improved. Transplantation in infants requires an intensive multidisciplinary approach but yields excellent short- and long-term survival rates that are no different from those seen in older children or adults. Living donors should be used whenever possible. Patients with a successful transplantation experience improved growth and development, with excellent rehabilitation.

Adolescent↗
PubMed1990

The use of cadaver kidneys for transplantation in young children.

The role of cadaver kidney transplantation in the management of end-stage renal disease in young children is controversial. To assess the current risk-benefit ratio of cadaver first and second kidney transplants in recipients under 6 years of age, we compared the outcome of 19 transplants performed between 1984 and 1989 using a quadruple-drug regimen (Minnesota antilymphocyte globulin, azathioprine, prednisone, cyclosporine) with the outcome of 25 transplants performed prior to 1984 without the use of cyclosporine at a single institution. Twenty-five transplants were in children under the age of 3 years. In the last decade patient survival has significantly improved. One-year patient survival improved from 53% before 1979 to 90% since 1979 (P less than 0.05). The use of the quadruple-drug regimen since 1984 was associated with a significant improvement in one-year cadaver graft function from 40% before 1979 to 78% in recipients under 6 years of age, and from 22% to 82% in recipients under 3 years of age (P less than 0.05). With the quadruple-drug regimen, one-year and four-year graft function rates for children under 6 years of age were 83% for first cadaver transplants and 72% for second cadaver transplants, which were essentially the same results as in older children and adults. Children who received kidneys from donors over 4 years of age achieved the best result, with 87% one-year graft function compared with 50% for kidneys from donors under 4 years old. In 15 children with successful transplants, 8 (53%) showed accelerated growth, 5 (33%) had normal-velocity growth, and only 2 children (14%) with suboptimal renal function had poor growth following transplantation. Therefore, we believe that with a quadruple-drug immunosuppressive protocol, cadaver renal transplantation using kidneys from adults or pediatric donors over 4 years old is an acceptable form of treatment in young children with end-stage renal disease for whom there are no suitable living-related donors.

Adolescent↗
PubMed1990

Colorado IDDM Registry. Incidence and validation of IDDM in children aged 0-17 yr.

The purpose of this study was to determine the incidence of insulin-dependent diabetes mellitus (IDDM) among children aged 0-17 yr for age, sex, season, and urban and rural residence of onset in Colorado. Retrospective registration of new-onset cases was conducted from 1978 to 1980, and then prospective registration continued through 1983 with the use of physician reporting with hospital validation. The annual incidence of IDDM was 15.2/100,000 per year (95% confidence interval [CI] 14.1, 16.3), with little difference between the sexes. The highest incidence was in the 10- to 14-yr age-group for both sexes. There was a seasonal peak of winter onset in those aged 10-17 yr, with similar patterns between sex and ethnic groups. No temporal trend over the 6 yr was seen, although an excess of cases was seen for 15- to 17-yr-old boys in 1980-1982. Rates were similar for urban and rural areas of the state. Case ascertainment was estimated to be 93.2% complete (95% CI 91.5, 95.5). Incidence was similar in Colorado to other populations in the United States at similar latitudes. These data serve as a baseline for evaluation of changes in incidence over time, by region, and for the identification of possible outbreaks.

Adolescent↗
PubMed1990

The control of reaching movements by young infants.

Samples of reaches were obtained from groups of infants aged 4.5, 6, and 7.5 months. Split-screen video recordings were transcribed as sequences of (x,y,z) hand coordinates, and the hand path was examined for evidence of initial aiming and subsequent correction of the movement path. At all ages, the initial direction of the movement was correlated with target direction, providing evidence that the hand was aimed toward the target. Additionally, changes in movement direction made after the commencement of the movement tended to curve the hand path toward the target, providing evidence of error correction. Local minima of hand speed evident within segments of continuous motion were associated with turn toward the target. However, the movement path was also curved toward the target within the movement elements bounded by these minima. This finding was seen as consistent with "continuous" correction of movement errors and as contrary to the suggestion that infant movements are concatenations of ballistic movement units whose boundaries are marked by troughs in the speed profile.

Attention↗
PubMed1990

Selective associations in the observational conditioning of fear in rhesus monkeys.

Three experiments explored the issue of selective associations in the observational conditioning of fear. Experiment 1 results indicated that observer rhesus monkeys acquired a fear of snakes through watching videotapes of model monkeys behaving fearfully with snakes. In Experiment 2, observers watched edited videotapes that showed models reacting either fearfully to toy snakes and nonfearfully to artificial flowers (SN+/FL-) or vice versa (FL+/SN-). SN+/FL- observers acquired a fear of snakes but not of flowers; FL+/SN- observers did not acquire a fear of either stimulus. In Experiment 3, monkeys solved complex appetitive discriminative (PAN) problems at comparable rates regardless of whether the discriminative stimuli were the videotaped snake or the flower stimuli used in Experiment 2. Thus, monkeys appear to selectively associate snakes with fear.

Animals↗
PubMed1989

Segmental expression of Hox-2 homoeobox-containing genes in the developing mouse hindbrain.

The vertebrate hindbrain develops in a segmental pattern, with distinctive groups of neurons originating from different segments. We report here that members of the Hox-2 cluster of murine homoeobox genes are expressed in segment-specific patterns in the developing hindbrain, with successive genes having boundaries at two-segment intervals. These data indicate that Hox genes specify segment phenotype, a role analogous to that of their Drosophila homologues.

Animals↗
PubMed1989

Fluorochrome labelling in Roman period skeletons from Dakhleh Oasis, Egypt.

A histological aging study of femoral midshafts in a late Roman period sample from the Dakhleh Oasis, Egypt, showed discrete fluorochrome labelling. The fluorochrome is yellow-green in colour and fluoresces at a wavelength of 525 nm. The labelling occurs at the mineralization fronts and is so distinct that several histomorphometric measurements were made. The percent labelled surface values ranged from 6.03% to 59.34%, and the mean distance between labels ranged from 13.57 to 20.63 microns. Teeth from several individuals were also labelled within the enamel matrix. Comparisons were made between the patterns of fluorescent labelling from this population and from patients treated with interval and continuous dosages of tetracycline. The results collectively indicate that the fluorochrome is most likely tetracycline that made its way into the bone (in vivo) via stored grain contaminated by Streptomycetes. The labelling was differential, much like that of the patient on interval doses of tetracycline, so it is argued that the tetracycline was ingested occasionally, probably on a seasonal basis. The lack of bone infection in the adults (n = 29) suggests that the tetracycline may have provided some antibiotic protection in this population.

Bone and Bones↗
PubMed1989

Fear-relevant selective associations and covariation bias.

Three experiments used an illusory correlation paradigm to assess the effects of fear on the perception of the covariation between fear-relevant stimuli and shock. In Experiment 1, high- and low-fear women were exposed to 72 trials during each of which a fear-relevant (snake or spider) or fear-irrelevant (mushroom and flower) slide was followed by a shock, a tone, or nothing. Although the relation between slide types and outcomes was random, high-fear subjects markedly overestimated the contingency between feared slides and shock. Experiment 2 showed that this bias was due to the aversive, rather than more generally salient, features of shock. Low-fear subjects demonstrated biases equivalent to those of high-fear subjects only when the base rate of shock was increased from 33% to 50% in Experiment 3. It is concluded that fear may be linked to biases that serve to confirm fear. The relevance of the present findings to preparedness theory is also discussed.

Association↗
PubMed1989

Observational conditioning of fear to fear-relevant versus fear-irrelevant stimuli in rhesus monkeys.

Two experiments examined whether superior observational conditioning of fear occurs in observer rhesus monkeys that watch model monkeys exhibit an intense fear of fear-relevant, as compared with fear-irrelevant, stimuli. In both experiments, videotapes of model monkeys behaving fearfully were spliced so that it appeared that the models were reacting fearfully either to fear-relevant stimuli (toy snakes or a toy crocodile), or to fear-irrelevant stimuli (flowers or a toy rabbit). Observer groups watched one of four kinds of videotapes for 12 sessions. Results indicated that observers acquired a fear of fear-relevant stimuli (toy snakes and toy crocodile), but not of fear-irrelevant stimuli (flowers and toy rabbit). Implications of the present results for the preparedness theory of phobias are discussed.

Animals↗
PubMed1989

Guillain-Barré syndrome and related conditions in Victorian teaching hospitals 1980-84.

Cases of Guillain-Barré syndrome, its variants, and chronic inflammatory demyelinating neuropathy presenting during the period 1980-84 were identified through computer-based record systems. Case notes were examined, and cases that did not meet standard criteria for diagnosis were excluded. A hundred and ten patients were identified, giving an annual adult incidence rate of 0.9/100,000 and a male:female ratio of 1.3:1. The majority of cases developed severe tetraparesis, but unusual presentations included the Miller-Fisher variant, paraplegia, and bibrachial involvement. There was wide variation in peak disability, ranging from ambulant with weakness (32%), through bedfast but without significant respiratory involvement (29%), to respiratory involvement requiring admission to an intensive care unit (38%). Of those discharged directly home, the average hospital stay for those less than 50 years was 27 days, whilst that for those over 50 was 49 days. CSF protein was measured in 87 patients, and was greater than or equal to 0.6 g/L in 76% of these. Nerve conduction studies were performed in 52 patients, and were abnormal in 90% of these. Guillain-Barré syndrome and allied conditions represent a major drain on health resources, and the need to provide adequate plasmapheresis facilities for patients early in the course of severe disease is stressed.

Adolescent↗
PubMed1989

Lead absorption in indoor firing range users.

To determine if users of indoor firing ranges may be at risk from lead exposure, we studied a law enforcement trainee class during three months of firearms instruction. Blood lead levels were obtained before training and at four-week intervals during training. Air lead levels were measured three times during instruction. Blood lead levels rose from a pre-training mean of 0.31 mumol/L to 2.47 mumol/L. Mean air lead levels were above 2,000 micrograms/m3, more than 40 times the Occupational Safety and Health Administration's standard of 50 micrograms/m3. Cumulative exposure to lead and the change in blood lead were positively correlated. Control measures need to be studied to determine their efficacy in decreasing or eliminating this health risk.

Air Pollutants↗
PubMed1988

Possible case of hyperparathyroidism in a Roman period skeleton from the Dakhleh Oasis, Egypt, diagnosed using bone histomorphometry.

A histomorphometric study of thin femoral head sections of a skeletal sample from the Dakhleh Oasis, Egypt, dated from circa 36 B.C. to 400 A.D., identified an adult female (Dk31-A1) in her mid-50s with a high percentage resorption surface with tunneling resorption as is typically found in hyperparathyroidism. Five static histomorphometric bone parameters were measured with the following results for this individual: 1) mean wall thickness, 41.94 micron, 2) trabecular bone volume, 18.54%, 3) surface volume, 4,070 mm2/cm3, 4) mean trabecular diameter, 132 microns, and 5) total resorption surface, 12.31%. The overall histomorphometric features and differential diagnosis support the diagnosis of hyperparathyroidism. We conclude that histomorphometry of dried bone, particularly in this case where preservation is ideal, is a valuable investigative technique for paleopathology.

Bone and Bones↗