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J C Morris

Publications and source records attributed to J C Morris.

At least 199 records · Page 11Linked to original sources
PubMed1994

A glycosylphosphatidylinositol (GPI)-negative phenotype produced in Leishmania major by GPI phospholipase C from Trypanosoma brucei: topography of two GPI pathways.

The major surface macromolecules of the protozoan parasite Leishmania major, gp63 (a metalloprotease), and lipophosphoglycan (a polysaccharide), are glycosylphosphatidylinositol (GPI) anchored. We expressed a cytoplasmic glycosylphosphatidylinositol phospholipase C (GPI-PLC) in L. major in order to examine the topography of the protein-GPI and polysaccharide-GPI pathways. In L. major cells expressing GPI-PLC, cell-associated gp63 could not be detected in immunoblots. Pulse-chase analysis revealed that gp63 was secreted into the culture medium with a half-time of 5.5 h. Secreted gp63 lacked anti-cross reacting determinant epitopes, and was not metabolically labeled with [3H]ethanolamine, indicating that it never received a GPI anchor. Further, the quantity of putative protein-GPI intermediates decreased approximately 10-fold. In striking contrast, lipophosphoglycan levels were unaltered. However, GPI-PLC cleaved polysaccharide-GPI intermediates (glycoinositol phospholipids) in vitro. Thus, reactions specific to the polysaccharide-GPI pathway are compartmentalized in vivo within the endoplasmic reticulum, thereby sequestering polysaccharide-GPI intermediates from GPI-PLC cleavage. On the contrary, protein-GPI synthesis at least up to production of Man(1 alpha 6)Man(1 alpha 4)GlcN-(1 alpha 6)-myo-inositol-1-phospholipid is cytosolic. To our knowledge this represents the first use of a catabolic enzyme in vivo to elucidate the topography of biosynthetic pathways. GPI-PLC causes a protein-GPI-negative phenotype in L. major, even when genes for GPI biosynthesis are functional. This phenotype is remarkably similar to that of some GPI mutants of mammalian cells: implications for paroxysmal nocturnal hemoglobinuria and Thy-1-negative T-lymphoma are discussed.

Animals↗
PubMed1994

Cisplatin, vinblastine, and hydrazine sulfate in advanced, non-small-cell lung cancer: a randomized placebo-controlled, double-blind phase III study of the Cancer and Leukemia Group B.

PURPOSE: To assess the chemotherapy regimen of cisplatin, vinblastine, and hydrazine sulfate administered to patients with non-small-cell lung cancer (NSCLC) in a randomized, placebo-controlled double-blind phase III study. PATIENTS AND METHODS: Between July 25, 1989 and February 1, 1991, 291 patients with stage IIIB or IV NSCLC and performance status 0 or 1 were randomized to receive cisplatin 100 mg/m2 intravenously (IV) every 28 days, vinblastine 5 mg/m2 IV per week times five, then every 2 weeks; and either hydrazine sulfate 60 mg three times per day orally or placebo. The concurrent use of corticosteroids, medroxyprogesterone, or other appetite stimulants was not permitted. Treatment groups were comparable for known prognostic variables. The primary end point of this study was survival; however, the influence of hydrazine sulfate on nutritional status, performance status, and quality of life was also assessed. RESULTS: Analysis of 266 eligible patients showed a median survival duration of 7.78 months for the hydrazine sulfate-treated group compared with 7.70 months for the placebo-treated group (P = .65, log-rank). Objective response rates were similar for the two groups, with 4% complete responses, 20% partial responses, and 2% regressions in those treated with hydrazine sulfate; 3% complete responses, 23% partial responses, and 2% regressions in those who received placebo. The major toxicity was severe or life-threatening neutropenia, which occurred in 65% of hydrazine sulfate patients and 63% of placebo patients. There were no differences noted between the two groups in degree of anorexia, weight gain or loss, or overall nutritional status. Sensory and motor neuropathy occurred significantly more often in patients treated with hydrazine sulfate. Quality of life was significantly worse in patients who received hydrazine sulfate. CONCLUSION: This study suggests no benefit from the addition of hydrazine sulfate to an effective cytotoxic regimen.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Thyrotropin (TSH) interacts with multiple discrete regions of the TSH receptor: polyclonal rabbit antibodies to one or more of these regions can inhibit TSH binding and function.

As a means of identifying functional regions of the TSH receptor (TSHr), we immunized four rabbits with recombinant extracellular TSHr (ETSHr) protein and systematically evaluated their antibody response. The antibody response was characterized by testing serial serum samples for immunoglobulin G (IgG) against ETSHr protein and 26 synthetic peptides which span the entire ETSHr. Sera were also tested for their ability to block TSH binding to native TSHr. All four rabbits developed high serum IgG titers (>1:100,000) to ETSHr. None of the rabbits developed significant IgG titers against 11 of the peptides, but each showed persistent high titers against several of the others. After multiple inoculations of antigen, sera from 3 rabbits showed significant ability to block TSH binding. Based on the ability of peptides to reverse this blocking activity, we identified 3 regions of the TSHr (i.e. amino acids 292-311, 367-386, and 397-415) through which antibodies can block TSH binding. Moreover, antibodies purified on either peptide 292-311 or peptide 367-386 affinity columns could block both TSH binding and TSH-mediated activation of thyroid cells in culture. These studies show ETSHr protein is sufficient to induce production of functionally relevant antibodies. Furthermore, we have identified several sites on the TSHr through which antibodies can inhibit TSH binding, thus leading to identification of several potential TSH-binding regions.

Amino Acid Sequence↗
PubMed1994

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part VI. Family history assessment: a multicenter study of first-degree relatives of Alzheimer's disease probands and nondemented spouse controls.

Although familial factors in Alzheimer's disease (AD) are well established, uniform family-history assessment in genetic and epidemiologic studies of AD is needed to reconcile the divergent estimates of the cumulative risk of this illness among relatives of AD probands. To answer the need, the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) has developed a standardized Family History Assessment of AD to identify the presence of AD, Parkinson's disease (PD), and Down's syndrome (DS) in family members. This paper describes the use of this new assessment instrument in 118 patients with AD (estimated mean age at onset [+/- SD] = 64.5 +/- 7.7 years) and their nondemented spouses who were enrolled in 11 different CERAD sites in the U.S. The first-degree relatives of the probands with AD had a significantly greater cumulative risk (p < 0.005) of AD or primary progressive dementia (24.8%) than did the relatives of spouse controls (15.2%). Furthermore, the cumulative risk for this disorder among female relatives of probands was significantly greater than that among male relatives. There were no differences between the families of probands and controls for the numbers of affected first-degree relatives with PD or DS. This is the first reported multicenter family-history study of AD, and it supports earlier reports of familial factors in AD and indicates a higher risk to female relatives of AD probands. The CERAD Family History Assessment instrument may be useful for further multicenter and epidemiologic studies designed to delineate familial factors associated with AD.

Age of Onset↗
PubMed1994

Identification of epitopes and affinity purification of thyroid stimulating auto-antibodies using synthetic human TSH receptor peptides.

We prepared a series of overlapping peptides (29 in total, 20 amino acids each) containing the sequence of the entire extracellular domain of the human TSH receptor. Three peptides (181-200, 376-394, and EC3 (629-639)) bound IgG from patients with Graves' disease in an enzyme linked immunoassay. Peptide 181-200 bound IgG from 9 of 10, EC3 from 8 of 10, and 376-394 from 6 of 10 patients respectively, compared to 0 of 9 controls. We affinity purified TSHr auto-antibodies from four Graves' patients using the three above noted peptides bound to epoxy-activated sepharose. Thyroid stimulating activity was enriched in the bound fraction from at least two of the three peptide affinity columns in each of the four patients, although the pattern of affinity enrichment differed between patients. One patient was found to possess a combination of stimulatory and inhibitory TSHr antibodies and, after affinity purification, the anti-376-394 and anti-EC3 fractions were enriched in stimulatory activity, suggesting that those regions of the receptor were epitopes for stimulatory antibodies. However, affinity purification against peptide 181-200 produced an IgG preparation that was not stimulatory, but was a potent thyroid inhibitor. Thus, we have not only partially purified TSHr auto-antibodies, but also successfully separated stimulatory and inhibitory antibodies from a single patient using combination TSHr peptide affinity.

Blotting, Western↗
PubMed1994

Isolation and characterization of the human DTK receptor tyrosine kinase.

A cDNA encoding the human homologue of the murine DTK receptor tyrosine kinase has been isolated from a human brain library. The DTK cDNA encodes a mature protein of 850 amino acids with similar structural features to those of the murine receptor. The extracellular domain contains two immunoglobulin-like motifs and two fibronectin type III modules; features which define a new class of receptor tyrosine kinase. The human DTK gene has been mapped by fluorescent in situ hybridization to chromosome 15q15, and a DTK-related gene identified at chromosome 15q24. In fetal tissues, transcripts for DTK were detected in brain, kidney, lung and heart. Prominent expression was observed in the embryonal carcinoma cell line NT2/D1. Expression of the gene is up-regulated in adult tissues with high levels of expression in many regions of the adult brain. DTK is also abundantly expressed in adult kidney, testis, and ovary.

Adult↗
PubMed1994

Differential diagnosis of Alzheimer's disease.

AD is by far the leading cause of dementia, accounting for about 75% of cases. Vascular dementia and Parkinson's disease, with or without concomitant AD, are responsible for much of the remainder of pathologically confirmed causes of dementia. The differential diagnosis of AD remains clinically based; even in the absence of a biologic marker for the disease, diagnostic accuracy can be high. Informant interviews can be helpful in detecting early dementia and in distinguishing the various stages and features of AD. Characterization of phenotypic variants of AD and refinement of diagnostic criteria for the non-AD dementias is needed to clarify the inter-relationships of these conditions and facilitate molecular genetic and other basic investigations of the etiopathogenesis of AD.

Alzheimer Disease↗
PubMed1994

GPI phospholipase C from Trypanosoma brucei causes a GPI-negative phenotype in Leishmania major: I. Implications for GPI-negative mammalian cells; II. Compartmentalization of two GPI biosynthetic pathways.

The major surface macromolecules of the protozoan parasite Leishmania major, gp63 (a metalloprotease), and lipophosphoglycan (a polysaccharide) are glycosylphosphatidylinositol (GPI)-anchored. We expressed a cytoplasmic glycosylphosphatidylinositol phospholipase C (GPIPLC) in L. major in order to examine the topography of the protein-GPI and polysaccharide-GPI pathways. In L. major cells expressing GPIPLC cell-associated gp63 could not be detected in immunoblots. gp63 was secreted into the culture medium without ever receiving a GPI anchor. Putative protein-GPI intermediates LP-1 and LP-2 decreased about 10-fold. In striking contrast, lipophosphoglycan levels were unaltered. We conclude that reactions specific to the polysaccharide-GPI pathway are compartmentalized within the endoplasmic reticulum, thereby sequestering those intermediates from GPIPLC cleavage. Protein-GPI synthesis, at least up to production of Man(1 alpha 6)Man(1 alpha 4)GlcN(1 alpha 6)-myo-inositol-1-phospholipid, is cytosolic. To our knowledge, this represents the first use of a catabolic enzyme, in vivo, to elucidate the topography of biosynthetic pathways. Intriguingly, the phenotype of GPIPLC-expressing L. major, secretion of proteins with GPI addition signals, and depletion of protein-GPI anchor precursors, is similar to that of some protein-GPI mutants in higher eukaryotes. These findings have implications for paroxysmal nocturnal hemoglobinuria and Thy-1-negative T-lymphoma.

Animals↗
PubMed1993

Structure-function studies of the human thyrotropin receptor. Inhibition of binding of labeled thyrotropin (TSH) by synthetic human TSH receptor peptides.

We have probed the hormone binding regions of the entire putative extracellular domain of the human thyrotropin (TSH) receptor (hTSHr) using synthetic peptides. A series of 26 overlapping peptides comprising the complete sequence of the extracellular domain of hTSHr was synthesized. Each peptide (20 amino acid residues each) was tested for its ability to interact with TSH, as evidenced by inhibition of binding of labeled hormone to native, membrane bound TSH receptors. Four of the 26 peptides interacted with labeled TSH and inhibited its binding to thyroid membranes. The most potent of these peptides was 256-275, which inhibited 125I-bovine TSH binding with an IC50 of 31.7 +/- 1.3 microM. The remaining peptides were 16-35 (351 +/- 9.4 microM), 106-125 (282 +/- 20.5 microM), and 226-245 (951 +/- 245 microM). An additional peptide, 286-305, showed minimal activity, and the remaining 21 peptides showed no activity. Peptides 256-275, 106-125, and 16-35 also inhibited binding of 125I-human chorionic gonadotropin to ovarian membrane receptors, suggesting that those regions of the receptor are involved in binding of a common glycoprotein hormone structure such as the alpha-subunit. In contrast, peptides 226-245 and 286-305 did not inhibit human chorionic gonadotropin binding, suggesting that these two regions are involved in hormone-specific activity. Of interest is the finding that the latter two peptides are from regions of TSHr that are largely dis-homologous to the lutropin receptor, whereas the former three, with the exception of 16-35, are from regions that are largely homologous between the two receptors. The data suggest that multiple, discontinuous regions of the extracellular domain of hTSHr are involved in the binding of the hormone. Furthermore, the binding regions are localized to TSHr-specific sequences as well as to regions that are highly homologous to LHr. This suggests that homologous regions of the two receptors are likely to perform similar functions in the interaction with their specific hormone, suggesting that those regions may be involved in binding of the glycoprotein hormone common alpha-subunit.

Amino Acid Sequence↗
PubMed1993

Neuropathological indexes of Alzheimer's disease in demented and nondemented persons aged 80 years and older.

Subjects with clinically diagnosed senile dementia of the Alzheimer type (n = 37) and healthy controls (n = 5) were assessed clinically until death. Postmortem examination of the brain was performed at age 80 years or older. The brains of all of the group with dementia (except one that was found to have a non-Alzheimer dementia) had substantial densities of neocortical senile plaques regardless of dementia severity; the control brains had very few senile plaques. In those subjects with Alzheimer's disease, moderate correlations were found between dementia duration and severity (cognitive portion of the Blessed Dementia Scale and the Sum of Boxes from the Clinical Dementia Rating) and certain neuropathological lesions, both gross and microscopic. Densities of neocortical neurofibrillary tangles were related to degree of dementia; densities of neocortical senile plaques were unrelated. We conclude that (1) neocortical senile plaque densities differentiate very old subjects with Alzheimer's disease from nondemented controls, but there is a need for more postmortem studies of older persons who are free of dementia; and (2) among the microscopic lesions studied, densities of neocortical neurofibrillary tangles were most closely related to the degree and duration of dementia.

Aged↗
PubMed1993

Influence of age on clinical and psychometric assessment of subjects with very mild or mild dementia of the Alzheimer type.

OBJECTIVE: The influence of age on performance on clinical and psychometric assessments is examined in groups of nondemented persons and individuals with either very mild or mild dementia of the Alzheimer type (DAT). DESIGN: Initial clinical and psychometric assessments of persons enrolled in longitudinal studies of DAT and nondemented control subjects. SETTING: Alzheimer's Disease Research Center at Washington University, St Louis, Mo. PARTICIPANTS: Volunteer samples of 108 people (44 men, 64 women) with mild DAT, 61 people (30 men, 31 women) with very mild DAT, and 122 healthy nondemented people (45 men, 77 women) were recruited between 1979 and 1991. Age ranged from 54 to 87 years. Persons with confounding medical, neurologic, or psychiatric disorders were excluded. Dementia severity was staged using the Clinical Dementia Rating scale. MAIN OUTCOME MEASURES: Five brief quantitative clinical tests included in the 90-minute clinician administered protocol, as well as 14 tests included in a 2-hour psychometric test battery. RESULTS: Dementia severity affected performance on all measurements. Age did not influence performance on clinical assessments. There was a significant interaction between age and dementia severity on 10 of 14 psychometric measures. In general, older nondemented individuals performed less well than younger nondemented individuals while older mildly demented persons performed about the same as, or slightly better than, their younger counterparts. CONCLUSIONS: Age does not affect performance on brief clinical assessment instruments. However, age affects psychometric performance differently in cognitively intact persons when compared with persons with DAT. As a result, psychometric differentiation between cognitively normal and demented individuals is more difficult in older populations.

Aged↗
PubMed1993

Interlaboratory histopathologic assessment of Alzheimer neuropathology: different methodologies yield comparable diagnostic results.

Three investigators have applied different histopathologic methods (modified Bielschowsky silver methods, Congo red-gallocyanin) to differentiate Alzheimer's disease (AD) (n = 7 subjects; four with very mild dementia and three with moderate to advanced dementia) neuropathology from brain changes associated with aging in three nondemented individuals who had been evaluated using a validated dementia severity staging instrument [Washington University Clinical Dementia Rating (CDR)] generally within a year of death. The presence of elevated numbers of neocortical (frontal and temporal) diffuse, mature, and total senile plaques (SP) was strongly correlated with the presence of clinical AD but did not equate with CDR dementia severity. Neocortical neurofibrillary tangle (NFT) density as well as hippocampal NFT and SP density in this small series did not differentiate statistically between AD and controls. NFT density appeared to correlate with CDR better than SP density. Quantitative histopathologic assessment of AD markers in only a few brain regions can accurately predict the presence of clinical AD, including the very mild form of the disease. This is especially true for SP in the neocortex.

Aged↗
PubMed1993

Driving performance in persons with mild senile dementia of the Alzheimer type.

OBJECTIVE: To assess the effect of mild senile dementia of the Alzheimer type (SDAT) on driving ability. DESIGN: Cross-sectional study with correlation analysis. SETTING: A university-based Alzheimer's Disease Research Center, which evaluates community-living older adult volunteers, and the university's Program in Occupational Therapy. PARTICIPANTS: Healthy elderly controls (n = 13) and subjects with very mild (n = 12) and mild (n = 13) SDAT. Dementia severity was staged by the Washington University Clinical Dementia Rating. MEASUREMENTS: The driving ability of participants on the in-car road test was scored independently by a driving instructor, blinded to the study design and to the dementia status of the subjects, and an unblinded occupational therapist. Interview-based perceptions of driving ability were obtained independently from the subjects and their collateral sources. Attentional and visuospatial performances of the subjects were assessed prior to the road test. RESULTS: All control and very mild SDAT subjects were judged to be "safe" drivers (ie, passed the in-car road test), but five (40%) of the mild SDAT subjects had driving impairment sufficient to "fail" the road test. Neither subject self-assessment nor caregiver perceptions of driving ability consistently predicted driving performance. Attentional task performance correlated well with road test results. CONCLUSIONS: Some SDAT subjects retain "safe" driving skills. The greater the dementia severity, the greater the likelihood of poor driving ability. Performance-based (road test) evaluations are necessary to properly determine driving skills at present, but attention and other cognitive screening measures should be developed.

Aged↗
PubMed1993

Psychopathology in younger versus older persons with very mild and mild dementia of the Alzheimer type.

OBJECTIVE: The psychopathology associated with early-onset dementia of the Alzheimer type was investigated by comparing the prevalence of psychiatric symptoms in younger subjects (mean age = 59 years) who had very mild or mild dementia with that in older adults (mean age = 72) whose dementia was of equivalent severity. METHOD: Nondemented comparison subjects and persons with very mild or mild dementia of the Alzheimer type were recruited to participate in longitudinal studies. All subjects met strict inclusion and exclusion criteria. Information pertaining to personality changes, affective symptoms, and psychotic symptoms was included in the 90-minute semistructured, physician-administered interview, which was used to assign a clinical dementia rating according to published guidelines. The younger group were age 64 or younger and consisted of 20 nondemented subjects, 11 subjects with very mild dementia, and 18 subjects with mild dementia. The older group, described previously, were 64-83 years old and consisted of 83 nondemented subjects, 41 persons with very mild dementia, and 68 subjects with mild dementia. RESULTS: The psychopathology in the younger subjects was similar to that in the older group. Personality changes occurred in over 80% of the younger persons with very mild illness. Psychotic symptoms were present in over 40% of the younger persons with mild illness but were rare in the group with very mild dementia. CONCLUSIONS: Similar patterns of psychopathology in younger and more elderly persons with dementia of the Alzheimer type support the suggestion that these changes are direct effects of the illness on the CNS. Increased attention to documenting these noncognitive symptoms and studying various treatments is urgently needed.

Age Factors↗