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Biomedical subjects

J Loftus

Publications and source records attributed to J Loftus.

At least 19 recordsLinked to original sources

Efficacy and tolerability of sumatriptan tablets administered during the mild-pain phase of menstrually associated migraine.

Two randomised, double-blind, parallel-group, placebo-controlled clinical trials were conducted to assess the efficacy of sumatriptan tablets, 50mg and 100mg, for treatment during the mild-pain phase of a menstrually associated migraine among patients who typically experienced moderate to severe migraine preceded by an identifiable phase of mild pain. Subjects (n = 403 in Study 1 and n = 349 in Study 2) treated one menstrually associated migraine on an outpatient basis. The results demonstrate that sumatriptan tablets, 50 mg or 100 mg, were significantly more effective than placebo at conferring pain-free response 1 h and 2 h post-dose; migraine-free response (i.e. no pain and no associated symptoms) 2 h post-dose; returning patients to normal functioning 2 h post-dose; and conferring sustained freedom from pain from 2 through 24 h post-dose. Although the studies were not designed or statistically powered to show differences between the sumatriptan doses, a trend for slightly higher efficacy was observed for the 100-mg dose compared with the 50-mg dose on many measures. Both doses of sumatriptan were well-tolerated. The only adverse events reported in more than 2% of subjects in a treatment group were nausea, paresthesia, dizziness and malaise/fatigue, all of which were reported at incidences comparable to or slightly higher than those with placebo. Considered in the context of other findings, these data suggest that--with menstrually associated migraine as with non-menstrual migraine--optimal therapeutic benefit of sumatriptan tablets may be realised when they are administered during the mild-pain phase of an attack rather than delaying treatment until headache is moderate or severe.

Adolescent↗

Sumatriptan nasal spray for migraine: a review of studies in patients aged 17 years and younger.

This review considers the epidemiology, clinical manifestations and functional consequences of migraine in children and adolescents and surveys the studies establishing the efficacy and tolerability of sumatriptan nasal spray in this patient population. Although therapeutic advances in paediatric and adolescent migraine have lagged behind those in adult migraine, the first systematic studies of migraine medications in young patients have brought about progress in the past five years. These studies show that therapeutic approaches suitable for adult patients are not always applicable to paediatric and adolescent patients. Because of the unique characteristics of paediatric and adolescent migraine, it has been difficult to demonstrate in young patients the efficacy of oral sumatriptan and other triptan tablets, which are the medications of choice for adult migraine. With sumatriptan, this finding has proven to be a consequence of the form in which the drug was administered rather than the inherent properties of the drug. The availability of sumatriptan nasal spray allows the benefits of migraine-specific therapy to be extended to children and adolescents. In both well-controlled, single-episode studies and long-term, multiple-episode studies, sumatriptan nasal spray has been effective and well tolerated for the acute treatment of migraine in children and adolescents. Except for unpleasant taste, which is not significantly distressing to patients, sumatriptan nasal spray has a tolerability profile similar to thatof placebo in young patients.

Administration, Intranasal↗

No evidence for a parent-of-origin effect detected in the pattern of inheritance of schizophrenia.

BACKGROUND: Schizophrenia is a complex genetic disorder with no clear pattern of inheritance. Epigenetic modification of genes may thus play a role in its transmission. METHODS: In our study, 439 families with at least two ill siblings with schizophrenia (208 with unilineal transmission) were examined for evidence of a parent-of-origin effect (e.g., evidence of parental imprinting on the familial transmission of schizophrenia). RESULTS: No significant difference in the prevalence of maternal compared with paternal transmission was found. In addition, affected male subjects did not differ from affected female subjects in the proportion of their offspring diagnosed with schizophrenia. CONCLUSIONS: Although the transmission of schizophrenia may be influenced by epigenetic events, our study fails to find evidence that one epigenetic mechanism, a parent-of-origin imprinting effect, determines whether an individual expresses the illness.

Adult↗

Failure to establish linkage on the X chromosome in 301 families with schizophrenia or schizoaffective disorder.

The hypothesis that a gene for susceptibility to psychosis (specifically in the X-Y homologous class) is located on the sex chromosomes has been proposed. Such a gene would account for the excess of sex chromosome anomalous males and females in populations of patients with psychosis, a tendency towards concordance by sex within families, and sex differences associated with psychosis and its underlying brain pathology. In earlier studies we observed small positive LOD scores in Xp11, and in a more recent and larger cohort of 178 sibling pairs, a peak multipoint nonparametric LOD score of 1. 55 at the locus DXS8032 in Xq21. The present study with a new set of markers extended the cohort to 301 ill sibling pairs and their parents. Despite the increase in sample size, the LOD score did not increase. A peak NPL of 1.55 was observed at the locus DXS1068 in proximal Xp, a region remote from the previous report. Separating families into those who were more likely to have X chromosome inheritance (maternal with no male to male transmission) did not yield stronger findings. In spite of the evidence that psychosis is related to a sex-dependent dimension of cerebral asymmetry, it is concluded that no consistent linkage of schizophrenia to the X chromosome can be demonstrated. In the context of the general failure of replication of linkage in psychosis, the possibility that the genetic predisposition to psychosis is contributed to by epigenetic modification rather than variations in the nucleotide sequence has to be considered.

Chromosome Mapping↗

Lack of evidence for linkage to chromosomes 13 and 8 for schizophrenia and schizoaffective disorder.

A previous report [Blouin et al., 1998: Nat Genet 20:70-73] suggesting linkage to chromosomes 13q32 and 8p21 in families with schizophrenia led us to investigate these regions in a large set of 301 multiplex families with schizophrenia. Multipoint analyses failed to reveal evidence for linkage to any portion of chromosome 13, while only a weakly positive score was present on 8p using the identical marker reported in the earlier report. Failure to confirm the Blouin et al claims in a substantially larger cohort adds emphasis to the inconsistency of the findings concerning linkage in schizophrenia. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:235-239, 2000.

Chromosomes, Human, Pair 13↗

Factor structure and familiality of first-rank symptoms in sibling pairs with schizophrenia and schizoaffective disorder.

BACKGROUND: Since their introduction as diagnostic criteria by Schneider in 1937, nuclear symptoms have played a key role in concepts of schizophrenia, but their relationship to each other and to genetic predisposition has been unclear. AIMS: To ascertain the factor structure and familiality of nuclear symptoms. METHODS: Nuclear (Schneiderian) symptoms were extracted from case notes and interviews in a study of 103 sibling pairs with DSM-III-R schizophrenia or schizoaffective disorder. RESULTS: Principal components analysis demonstrated two major factors: one, accounting for about 50% of the variance, groups thought withdrawal, insertion and broadcasting, with delusions of control; and the second, accounting for < 20% of the variance, groups together third-person voices, thought echo and running commentary. Factor I was significantly correlated within sibling pairs. CONCLUSIONS: The correlation within sibling pairs suggests that, contrary to the conclusion of some previous studies, some nuclear symptoms do show a degree of familiality and therefore perhaps heritability.

Adolescent↗

A genome-wide search for schizophrenia susceptibility genes.

We completed a systematic genome-wide search for evidence of loci linked to schizophrenia using a collection of 70 pedigrees containing multiple affected individuals according to three phenotype classifications: schizophrenia only (48 pedigrees; 70 sib-pairs); schizophrenia plus schizoaffective disorder (70 pedigrees; 101 sib-pairs); and a broad category consisting of schizophrenia, schizoaffective disorder, paranoid or schizotypal personality disorder, psychosis not otherwise specified (NOS), delusional disorder, and brief reactive psychosis (70 pedigrees; 111 sib-pairs). All 70 families contained at least one individual affected with chronic schizophrenia according to DSM-III-R criteria. Three hundred and thirty-eight markers spanning the genome were typed in all pedigrees for an average resolution of 10.5 cM (range, 0-31 cM) and an average heterozygosity of 74.3% per marker. The data were analyzed using multipoint nonparametric allele-sharing and traditional two-point lod score analyses using dominant and recessive, affecteds-only models. Twelve chromosomes (1, 2, 4, 5, 8, 10, 11, 12, 13, 14, 16, and 22) had at least one region with a nominal P value <0.05, and two of these chromosomes had a nominal P value <0.01 (chromosomes 13 and 16), using allele-sharing tests in GENEHUNTER. Five chromosomes (1, 2, 4, 11, and 13) had at least one marker with a lod score >2.0, allowing for heterogeneity. These regions will be saturated with additional markers and investigated in a new, larger set of families to test for replication.

Chromosome Mapping↗

Evidence for linkage to psychosis and cerebral asymmetry (relative hand skill) on the X chromosome.

The hypothesis that psychosis arises as a part of the genetic diversity associated with the evolution of language generates the prediction that illness will be linked to a gene determining cerebral asymmetry, which, from the evidence of sex chromosome aneuploidies, is present in homologous form on the X and Y chromosomes. We investigated evidence of linkage to markers on the X chromosome in 1) 178 families multiply affected with schizophrenia or schizoaffective disorder with a series of 16 markers spanning the centromere (study 1), and 2) 180 pairs of left-handed brothers with 14 markers spanning the whole chromosome (study 2). In study 1, excess allele-sharing was observed in brother-brother pairs (but not brother-sister or a small sample of sister-sister pairs) over a region of approximately 20 cM, with a maximum LOD score of 1.5 at DXS991. In study 2, an association between allele-sharing and degree of left-handedness was observed extending over approximately 60 cM, with a maximum lod score of 2.8 at DXS990 (approximately 20 cM from DXS991). Within the overlap of allele-sharing is located a block in Xq21 that transposed to the Y chromosome in recent hominid evolution and is now represented as two segments on Yp. In one of two XX males with psychosis we found that the breakpoint on the Y is located within the distal region of homology to the block in Xq21. These findings are consistent with the hypothesis that an X-Y homologous determinant of cerebral asymmetry carries the variation that contributes to the predisposition to psychotic illness.

Female↗

Familial associations of subsyndromes of psychosis in affected sibling pairs with schizophrenia and schizoaffective disorder.

Attempts to describe the clinical heterogeneity of schizophrenia have consisted of categorical subtyping and a dimensional approach using factor analysis. The latter has yielded three dimensions or subsyndromes: positive, negative and disorganisation. The aim of this study is to explore to what degree these subsyndromes are correlated within 114 sibling pairs (185 individuals) with DSM-III-R schizophrenia or schizo-affective disorder who were assessed for the lifetime presence or absence of the positive, negative, affective and disorganisation subsyndromes. Ratings were based on the core symptoms of each subsyndrome using a modified Krawieka scale. First rank symptoms were also included in the analysis. Coincidence was assessed by application of the binomial theorem to the frequency of occurrence of subsyndromes in this set of siblings. The disorganisation subsyndrome was shared above chance expectation (chi2=9.15, P < 0.01 for all sibling pairs). The significant results for the disorganisation subsyndrome suggest that it may be a suitable phenotypic marker for genetic linkage studies.

Adult↗

A linkage study of schizophrenia to markers within Xp11 near the MAOB gene.

A sex chromosome locus for psychosis has been considered on the basis of some sex differences in genetic risk and expression of illness, and an association with X-chromosome anomalies. Previous molecular genetic studies produced weak evidence for linkage of schizophrenia to the proximal short arm of the X-chromosome, while some other regions were not ruled out. Here we report an attempt to expand the Xp findings in: (i) a multicenter collaboration focusing on 92 families with a maternal pattern of inheritance (Study I), and (ii) an independent sample of 34 families unselected for parental mode of transmission (Study II). In the multicenter study, a parametric analysis resulted in positive lod scores (highest of 1.97 for dominant and 1.19 for recessive inheritance at a theta of 0.20) for locus DXS7, with scores below 0.50 for other markers in this region (MAOB, DXS228, and ARAF1). Significant allele sharing among affected sibling pairs was present at DXS7. In the second study, positive lod scores were observed at MAOB (highest of 2.16 at a theta of 0.05 for dominant and 1.64 at a theta of 0.00 for recessive models) and ALAS2 (the highest of 1.36 at a theta of 0.05 for a recessive model), with significant allele sharing (P = 0.003 and 0.01, respectively) at these two loci. These five markers are mapped within a small region of Xp11. Thus, although substantial regions of the X-chromosome have been investigated without evidence for linkage being found, a locus predisposing to schizophrenia in the proximal short arm of the X-chromosome is not excluded.

Chromosome Mapping↗

Linkage analyses of schizophrenia to chromosome 6p24-p22: an attempt to replicate.

The present study evaluates evidence for linkage of schizophrenia to chromosome 6p24-p22. An independent sample of 211 families ascertained on the basis of having an affected sib-pair diagnosed with schizophrenia or schizoaffective disorder was assessed with seventeen polymorphic markers spanning a 37cM region. Linkage analysis was performed with parametric and non-parametric methods to test for cosegregation using 4 models of inheritance. Neither two-point nor multipoint non-parametric analyses reached significance at a level less than 0.01 for any markers examined in the region and lod score analyses were not suggestive of linkage. Based on initial findings in the present data set and recently published linkage results, two specific areas were densely covered with markers and tested for linkage disequilibrium. After correcting for multiple comparisons within each locus, no significant deviation from expected allele transmission ratios was observed. The present findings together with the published literature fail to find consistent evidence of a linkage for schizophrenia to a single locus on chromosome 6.

Adult↗

Anatomic variation of the middle cerebral artery in the Sprague-Dawley rat.

BACKGROUND AND PURPOSE: The aim of this study was to record and analyze the anatomy of the middle cerebral artery in the rat in an attempt to identify a potential source of variation of quantitative infarct measurements in commonly used models of focal cerebral ischemia. METHODS: Over a period of 22 months, as part of ongoing studies, we routinely induced focal cerebral ischemia in 263 Sprague-Dawley rats. This was achieved by permanent occlusion of a length of the right middle cerebral artery approximately 1 to 5 mm distal to the point at which it traverses the rhinal fissure combined with 60 minutes of bilateral common carotid occlusion. The branching pattern of the middle cerebral artery was recorded for each animal by drawing and photography before occlusion and at the time of death. RESULTS: Six distinct branching patterns were observed. The majority (82.9%) of middle cerebral arteries studied conformed to the typical bifurcating vessel commonly referred to in the literature. However, the remaining 17.1% were far more variable with major, atypical branching, introducing, we believe, unnecessary and avoidable variation into quantitative measurements of ischemia in this and similar models. CONCLUSIONS: Middle cerebral artery anatomy should be routinely recorded in models of focal cerebral ischemia in which this artery is occluded distal to the olfactory tract, thus allowing improved analysis of data.

Animals↗

Biochemical prediction of changes in spinal bone mass in juvenile chronic (or rheumatoid) arthritis treated with glucocorticoids.

OBJECTIVE: To identify biochemical predictors of spinal bone mineral growth and the development of spinal osteoporosis in children with juvenile chronic arthritis (JCA) treated with glucocorticoids. METHODS: Bone mass measurements were made at 3 monthly intervals for one year in 31 children. At each visit, blood and urine were obtained for assessment of laboratory indices related to the acute phase response and bone remodelling rates. Assessments were also made of joint inflammation (simple joint count). RESULTS: Plasma albumin and C-reactive protein (CRP) concentrations contributed independently of height velocity to the prediction of lumbar spinal bone mineral growth, but only when averaged over the year of observation. The simple joint count did not usefully predict spinal bone mineral changes in the individual patient, nor did any measured index normally related to bone turnover (plasma osteocalcin, 25 (OH) vitamin D, urinary hydroxyproline). Mean values of the simple joint count were predicted by mean CRP and CRP trends. Joint count trends were predicted by hemoglobin trends. None of these relationships, although statistically significant, was strong enough to predict individual outcomes precisely. CONCLUSIONS: Failure of spinal bone mineral growth is related to failure of growth in height and weight but also to biochemical markers for the activation of the acute phase response. Failure of bone growth to correlate with increased hydroxyprolinuria or plasma osteocalcin concentrations may be attributed to the confounding effect of glucocorticoid treatment on plasma osteocalcin levels in children whose bone resorption is little changed from normal levels despite their reduced growth. Biochemical measurements are weak substitutes for bone densitometry in monitoring spinal growth in these children.

Adolescent↗

Randomized, double-blind trial of deflazacort versus prednisone in juvenile chronic (or rheumatoid) arthritis: a relatively bone-sparing effect of deflazacort.

Thirty-four children with juvenile chronic (rheumatoid) arthritis were recruited to a randomized, double-blind study of deflazacort (an oxazolone derivative of prednisone) vs prednisone. All had been receiving glucocorticoid therapy for at least 1 year and required at least 5 mg/d of prednisolone (usually as 10 mg every 2 days). Thirty-one children completed the study. Bone density trends were measured in the spine by dual photon absorptiometry and in the forearm by single photon quantitative computed tomography at 3-monthly intervals. Trends (velocities) in bone and soft tissue growth were calculated. In the spine, bone growth correlated well with indices of soft tissue growth, but covariance analysis showed a significant advantage (P less than .007) of deflazacort when spinal bone mineral growth was compared to body surface area and weight. In part this was due to a temporary interruption in weight by children receiving deflazacort, whose gain in height was comparable with that of the prednisone group. Some children in both groups improved clinically and showed catch-up growth; in these children relative spinal bone mineral growth velocities were about twice those observed for height and weight. It is concluded that during the first year of deflazacort, their spinal bone mineral content at a level that was appropriate for their height and weight. Further observations are required to establish whether this advantage can be maintained subsequently. The anti-inflammatory effects of the two glucocorticoids appeared similar.

Adolescent↗

Effects of item-specific and relational information on hypermnesic recall.

The role of encoding conditions in producing hypermnesia (increased recall over successive trials) was examined by manipulating the availability of item-specific and relational information at encoding. Our findings demonstrate that encodings providing item-specific information (e.g., elaborative encodings) produce hypermnesia by facilitating the recovery of new items over trials, whereas encodings providing relational information (e.g., organizational encodings) produce hypermnesia by protecting against the loss of previously recalled items. Thus, the effects of encodings on hypermnesia may be understood by considering the type of trace information they make available.

Adult↗

cDNA clones for human platelet GPIIb corresponding to mRNA from megakaryocytes and HEL cells. Evidence for an extensive homology to other Arg-Gly-Asp adhesion receptors.

Platelet glycoprotein (GP) IIb is one of the two subunits of the common platelet adhesion receptor, GPIIb-IIIa. The isolation, characterization and sequencing of cDNA clones encoding for the two polypeptide chains of GPIIb are described. A number of clones were isolated from lambda gt11 libraries constructed with mRNA from an erythroleukemic cell line, HEL, and human megakaryocytes. Two of these clones, lambda IIb1, from HEL cells, and lambda IIb2, from megakaryocytes, cross-hybridized and were selected for detailed analysis. The identification of these as authentic GPIIb clones was based on immunological criteria and confirmed by the presence of nucleotide sequences in each insert encoding for known protein sequences of platelet GPIIb. These clones contained inserts of 1.54 kb and 1.39 kb, respectively, with an overlapping sequence of 801 bp. The nucleotide sequence of the overlapping region was identical indicating that HEL cells produce a protein closely related, if not identical, to platelet GPIIb. The determined nucleotide sequence of two inserts included a coding sequence for 648 amino acid residues, a TAG stop codon and 185 nucleotides of 3' non-coding sequence followed by a poly(A) tail. The coding sequence contained a portion of the heavy chain, the junction between the heavy and light chains and the entire light chain including a potential transmembrane-spanning domain and a short cytoplasmic tail. When these cDNA were used to probe for GPIIb mRNA, a single mRNA species of 3.9 kb was identified in both HEL cells and human megakaryocytes. A comparison of the deduced amino acid sequence for GPIIb with those of the alpha subunit of the vitronectin and the fibronectin receptors revealed extensive homologies. These homologies further establish that GPIIb-IIIa from platelets, together with the vitronectin and the fibronectin receptors, are members of a supergene family of adhesion receptors with a recognition specificity for Arg-Gly-Asp amino acid sequences.

Amino Acid Sequence↗