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Biomedical subjects

D J Clarke

Publications and source records attributed to D J Clarke.

At least 55 records · Page 3Linked to original sources
PubMed1998

Process recording: of what value is examining nursing interaction through assignment work?

This paper comprises a brief examination of the concept of process recording and its current applications in nursing and health-related professions. The possible benefits and problems of using the process recording tool as a summative assignment method within a nursing diploma course will be discussed in the light of experience at one former college of health in the North of England. The author argues that the process recording assignment offers a useful means of relating communication theory to practice and an opportunity for students to engage in reflection on their practice in a structured way.

Attitude of Health Personnel↗
PubMed1998

Psychopharmacology of severe self-injury associated with learning disabilities.

BACKGROUND: Many sedative and antipsychotic agents have been used in the management of severe self-injury associated with learning disabilities. Their efficacy has been questioned. Recent research has identified some biological abnormalities associated with severe self-injury and allowed a more rational selection of treatment. METHOD: Review of published literature, including trials, previous reviews and case reports. REPORTS: There is evidence for the efficacy of opiate antagonists in the management of severe self-injury, and recent research has identified potential methods of predicting treatment response. Dopamine D1 antagonists and some agents affecting serotonin turnover may also be of benefit. CONCLUSIONS: More rational psychopharmacological treatments for severe self-injurious behaviour may become available. Such treatments are difficult to evaluate for methodological and ethical reasons. They usually involve the clinical use of compounds for unlicensed indications, rather than trials of agents developed specifically to treat severe self-injurious behaviour. Combining psychopharmacological and psychological interventions may provide additional benefits.

Humans↗
PubMed1998

Problem behaviors associated with deletion Prader-Willi, Smith-Magenis, and cri du chat syndromes.

Problem behaviors of individuals who had one of three chromosome deletion disorders (5p- cri-du-chat, 15q- Prader-Willi, or 17p- Smith-Magenis) were investigated. The Aberrant Behavior Checklist was used. Results were contrasted with those of two groups of people with mental retardation who were described in other studies. The checklist rates many, but not all, potentially relevant behaviors. Eating abnormalities, known to be problematic in Prader-Willi syndrome, and sleep abnormalities, believed to be problematic in Smith-Magenis syndrome, were not included in the survey. All three disorders were associated with greater ratings of problem behaviors than the comparison groups on at least one subscale of the checklist. The results lend support to the partial specificity model of behaviors associated with genetically determined syndromes.

Adolescent↗
PubMed1998

Obturator hernia: a new technique for repair.

An obturator hernia is exceedingly rare and the diagnosis is usually made at laparotomy for small bowel obstruction. Several methods of dealing with the hernial defect have been described. Two cases of obturator hernias in nonagenarians are reported and a new, simple and effective method of repairing the hernia by suturing a polypropylene (Prolene) mesh to Cooper's ligament is proposed.

Aged↗
PubMed1997

Age changes in dopamine levels in the corpus striatum of Albino Swiss (AS) and AS/AGU mutant rats.

The AS/AGU rat is characterised by an ungainly, staggering gait, hind-limb rigidity, whole body tremor and (in older animals) difficulty in initiating movement. Brains of AS and AS/AGU males aged between 3 and 12 months (n = 10 per group) were sectioned transversely on a cryostat (-20 degrees C) to produce two successive cut faces (corresponding approximately to Bregma +1.2 and -0.5 mm) and 1 mm diameter x 1 mm deep micropunches were taken from four areas of the caudate-putamen. Levels of dopamine in all four areas (measured by HPLC-ECD followed by protein estimation) peaked at around 6 months and then declined in AS and AS/AGU rats. In the dorsal and lateral caudate-putamen, dopamine levels were significantly reduced in AS/AGU rats compared to AS controls from 6 months onwards. This provides further evidence that the AS/AGU mutant has impairment of its striatal dopaminergic systems.

Age of Onset↗
PubMed1997

Genetic defects of the UDP-glucuronosyltransferase-1 (UGT1) gene that cause familial non-haemolytic unconjugated hyperbilirubinaemias.

Congenital familial non-haemolytic hyperbilirubinaemias are potentially lethal syndromes caused by genetic lesions that reduce or abolish hepatic bilirubin UDP-glucuronosyltransferase activity. Here we describe genetic defects that occur in the UGT1 gene complex that cause three non-haemolytic unconjugated hyperbilirubinaemia syndromes. The most severe syndrome, termed Crigler-Najjar syndrome type I, is mainly associated with mutations in exons 2 to 5 that affect all UGT1 enzymes and many of the mutations result in termination codons and frameshifts. Crigler-Najjar type II syndrome which is treatable with phenobarbital therapy is associated with less dramatic missense mutations or heterozygous expression of mutant and normal alleles. Gilbert's syndrome, the most prevalent (2-19% in population studies) and mildest of the three syndromes is principally caused by a TA insertion at the TATA promoter region upstream of the UGT1A1 exon. Current methods used for the diagnosis and treatment of these diseases are discussed.

Crigler-Najjar Syndrome↗
PubMed1997

The role of sister chromatid cohesiveness and structure in meiotic behaviour.

Sister chromatid cores, kinetochores and the connecting strand between sister kinetochores were differentially silver stained to analyse the behaviour of these structures during meiosis in normal and two spontaneous desynaptic individuals of Chorthippus jucundus (Orthoptera). In these desynaptic individuals most of the chromosomes appear as univalents and orient equationally in the first meiotic division. Despite this abnormal segregation pattern, the changes in chromosome structure follow the same timing as in normal individuals and seem to be strictly phase dependent. Chromosomes in the first prometaphase have associated sister kinetochores and sister chromatid cores that lie in the chromosome midline; we propose that this promotes the initial monopolar orientation of chromosomes. However, the requirements of tension for stable attachment to the spindle force the autosomal univalents to acquire amphitelic orientation. Sister kinetochores behave in a chromosome orientation-dependent manner and, in the first metaphase, they appear to be interconnected by a strand that can be detected by silver impregnation, as seen in the second metaphase of wild-type individuals. The disappearance of the sister kinetochore-connecting strand, needed for equational chromatid segregation, however, can only take place in the second meiotic division. This connecting strand is ultimately responsible for the inability of chromosomes to segregate sister chromatids in the first anaphase.

Animals↗
PubMed1997

Identification of genes controlling growth polarity in the budding yeast Saccharomyces cerevisiae: a possible role of N-glycosylation and involvement of the exocyst complex.

The regulation of secretion polarity and cell surface growth during the cell cycle is critical for proper morphogenesis and viability of Saccharomyces cerevisiae. A shift from isotropic cell surface growth to polarized growth is necessary for bud emergence and a repolarization of secretion to the bud neck is necessary for cell separation. Although alterations in the actin cytoskeleton have been implicated in these changes in secretion polarity, clearly other cellular systems involved in secretion are likely to be targets of cell cycle regulation. To investigate mechanisms coupling cell cycle progression to changes in secretion polarity in parallel with and downstream of regulation of actin polarization, we implemented a screen for mutants defective specifically in polarized growth but with normal actin cytoskeleton structure. These mutants fell into three classes: those partially defective in N-glycosylation, those linked to specific defects in the exocyst, and a third class neither defective in glycosylation nor linked to the exocyst. These results raise the possibility that changes in N-linked glycosylation may be involved in a signal linking cell cycle progression and secretion polarity and that the exocyst may have regulatory functions in coupling the secretory machinery to the polarized actin cytoskeleton.

Cloning, Molecular↗
PubMed1997

Point mutations in the transmembrane domain of DjlA, a membrane-linked DnaJ-like protein, abolish its function in promoting colanic acid production via the Rcs signal transduction pathway.

DjIA is a novel DnaJ-like protein localized to the inner membrane of Escherichia coli through the single transmembrane domain (TMD) found at the N-terminus. The overproduction of DjIA activates expression of the cps operon, controlling synthesis and export of the extracellular polysaccharide colanic acid via the Rcs/B two-component signal transduction pathway. We now show that both the TMD and the J-region are essential for the induction of cps expression observed with the overproduction of DjIA. Furthermore, we describe the isolation and characterization of different point mutations in the TMD that completely or partially block the induction of cps expression associated with overproduction of DjIA. These mutations were shown not to affect the localization, stability or topology of the mutant DjIA proteins. We propose that these mutations are affecting specific interactions between the TMD of DjIA and its substrate protein(s), for example RcsC, the membrane sensor kinase partner of the Rcs/B signal transduction pathway.

Antibodies, Bacterial↗
PubMed1997

Correlates of maladaptive behavior in individuals with 5p- (cri du chat) syndrome.

This study examined the range, distinctiveness, and correlates of maladaptive behavior in 146 subjects with 5p- (cri du chat) syndrome using the Aberrant Behavior Checklist as a standardized measure. Hyperactivity was the most significant and frequent problem in the sample. Subjects with 5p- syndrome also showed aggression, tantrums, self-injurious behavior, and stereotypies; some of these problems were more pronounced in individuals with lower cognitive-adaptive levels, as well as in those with histories of previous medication trials. Autistic-like features and social withdrawal were more characteristic of individuals with translocations as opposed to deletions, even when controlling for the lower adaptive level of the translocation group. These findings encourage further research on the behavior of individuals with 5p- syndrome.

Adjustment Disorders↗
PubMed1996

Neostriatal dopamine depletion and locomotor abnormalities due to the Albino Swiss rat agu mutation.

The sub-strain of Albino Swiss rat (AS/AGU) is a spontaneous mutation characterised by an ungainly, staggering gait, hindlimb rigidity, whole body tremor and (when symptoms are fully developed) difficulty in initiating movement; it exhibits a progressive decrease in dopaminergic cells within the substantia nigra. A breeding programme involving Albino Swiss (AS) and AS/AGU parent rats was used to produce the F1 offspring of AS x AS/AGU matings and, subsequently, F1 x AS/AGU back crosses. When adult, the movement of all animals was assessed blind by observers on three occasions, each animal being identifiable by a subcutaneous transponder implanted before weaning. All AS/AGU and half the F1 x AS/AGU back cross animals had abnormal gait, while all AS, F1 and the remaining F1 x AS/AGU backcross animals showed normal gait, implying that the mutation is recessive. Brains of males aged 12-15 months (n = 10 per group) were sectioned transversely on a cryostat (-20 degrees C) to produce a cut face just caudal to the anterior commissure (approximately Bregma -0.5 mm) and 1 mm diameter x 1 mm deep micropunches were taken from three areas of the caudate-putamen. Levels of dopamine were measured in all samples by high performance liquid chromatography with electrochemical detection (HPLC-ECD) followed by protein estimation. Levels of dopamine in the dorsal and middle caudate-putamen varied according to a simple inheritance pattern, being high in males from AS, F1 and F1 x AS/AGU back crosses without locomotor impairment, but lower in AS/AGU and F1 x AS/AGU back crosses with disordered gait. Dopamine levels in the ventral caudate-putamen did not show such a clear variation.

Animals↗
PubMed1996

Survival and differentiation of rat and human epidermal growth factor-responsive precursor cells following grafting into the lesioned adult central nervous system.

Epidermal Growth Factor (EGF)-responsive stem cells isolated from the developing central nervous system (CNS) can be expanded exponentially in culture while retaining the ability to differentiate into neurons and glia. As such, they represent a possible source of tissue for neural transplantation, providing they can survive and mature following grafting into the adult brain. In this study we have shown that purified rat stem cells generated from either the embryonic mesencephalon or the striatum can survive grafting into the striatum of rats with either ibotenic acid or nigrostriatal dopamine lesions. However, transplanted stem cells do not survive as a large mass typical of primary embryonic CNS tissue grafts, but in contrast form thin grafts containing only a small number of surviving cells. There was no extensive migration of transplanted stem cells labeled with either the lac-z gene or bromodeoxyuridine into the host region surrounding the graft, although a small number of labeled cells were seen in the ventral striatum some distance from the site of implantation. Some of these appeared to differentiate into dopamine neurons, particularly when the developing mesencephalon was used as the starting material for generating the stem cells. EGF-responsive stem cells could also be isolated from the mesencephalon of developing human embryos and expanded in culture, but only grew in large numbers when the gestational age of the embryo was greater than 11 weeks. Purified human CNS stem cells were also transplanted into immunosuppressed rats with nigrostriatal lesions and formed thin grafts similar to those seen when using rat stem cells. However, when primary cultures of human mesencephalon were grown with EGF for only 10 days and this mixture of stem cells and primary neural tissue was transplanted into the dopamine-depleted striatum, large well-formed grafts developed. These contained mostly small undifferentiated cells intermixed with a number of well-differentiated TH-positive neurons. These results show that purified populations of rat or human EGF-responsive CNS stem cells do not form large graft masses or migrate extensively into the surrounding host tissues when transplanted into the adult striatum. However, modifications of the growth conditions in vitro may lead to an improvement of their survival in vivo.

Animals↗
PubMed1996

Maladaptive behaviour in Prader-Willi syndrome in adult life.

Thirty adults with Prader-Willi syndrome (PWS) were compared with 30 adults with non-specific learning disability matched for age, sex and severity of mental retardation. Maladaptive behaviour was assessed with the Aberrant Behavior Checklist (ABC), a 58-item structured interview which rates behaviours from 0 (not a problem) to 3 (severe problem) and which yields five factors (I) irritability, agitation; (II) lethargy, withdrawal; (III) stereotypic behavior; (IV) hyperactivity, non-compliance; and (V) inappropriate speech). The PWS sample had significantly higher factor I (P < 0.001) and factor V (P < 0.05) scores. The PWS sample had mean scores above 1 for 17 ABC items; the contrast subjects had no mean scores above 1. The factor I scores for the PWS sample were similar to those of inpatients in hospital facilities for adults with mental retardation and mental illness or severely challenging behaviour. The results support previous work, and extend it by suggesting that temper tantrums, self-injury, impulsiveness, lability of mood, inactivity and repetitive speech are characteristic behaviours in PWS in adult life. Studies of the reasons for heterogeneity in behaviour are now needed.

Activities of Daily Living↗