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Biomedical subjects

C Thomas

Publications and source records attributed to C Thomas.

At least 253 records · Page 14Linked to original sources
PubMed1994

Papillary (malignant) meningioma of the foramen magnum presenting as a posterior neck mass.

Meningiomas and neurofibromas are the most common extramedullary tumors in the region of the foramen magnum. The clinical symptoms are variable, including headache, occipitocervical pain, and hoarseness. Neurological symptoms are present only in 40% of cases. The age group ranges from 4 to 56 years. A number of patients are misdiagnosed as multiple sclerosis, syringomyelia, and cervical disc disease. The overall incidence of these tumors vary from 1.6 to 2.4%. The majority of meningiomas are histologically benign. Papillary (malignant) meningiomas are even rarer in this location. The present report is that of a 46-year-old man who developed a painless mass in the nape of his neck, without any neurological symptoms. Following initial biopsy at another hospital, a definitive resection was undertaken at Loyola University Medical Center. The diagnosis of a malignant meningioma was made after extensive immunohistochemical and electron microscopic studies. The patient developed a positive cervical lymph node 1 year later, which was excised and showed identical histopathologic features.

Case Reports↗
PubMed1994

Monitoring of body weight during transurethral resection of the prostate: preliminary report.

The fear of vascular overload by irrigant during transurethral resection of the prostate is a reason for an incomplete resection. With continuous measurement of the patient's body weight and, thus, body water, irrigant entrance is immediately identified. We present a scale of proved accuracy and reliability, allowing more effective resection while eliminating the possibility of TUR syndrome.

Body Weight↗
PubMed1994

Can the uptake of breast screening by Asian women be increased? A randomized controlled trial of a linkworker intervention.

This study investigates the effectiveness of a linkworker intervention, giving encouragement and explanations about breast screening, on the subsequent attendance for screening by 'Asian' women. The control group received no visits. The study population comprised all women with Asian names, from a batch of general practices where high proportions of patients were Asian, who were invited for screening. It was found that 59 per cent of the intervention group could be contacted by linkworkers. No difference in attendance was found between the intervention and control groups (49 per cent and 47 per cent). Twenty-five per cent of women were permanently or temporarily not resident at the invitation address. Attendance for screening was related to length of stay in the United Kingdom. This type of intervention was not a successful strategy for promoting uptake by Asian women, and indicates that it is essential to evaluate rigorously projects with such objectives.

Aged↗
PubMed1994

Deletion and mutational analyses of bluetongue virus NS2 protein indicate that the amino but not the carboxy terminus of the protein is critical for RNA-protein interactions.

Genome segment 8 (S8) of bluetongue virus serotype 10 (BTV-10) encodes the nonstructural protein NS2. This protein, which has single-stranded RNA (ssRNA) binding capacity, is found in BTV-infected cells in the form of virus inclusion bodies (VIBs). To identify the domain(s) important for RNA binding and oligomerization of the protein, a number of deletions were made in regions of the gene that code for either the amino or carboxy terminus of the protein. The modified genes were cloned into and expressed from baculovirus vectors based on Autographa californica nuclear polyhedrosis virus. Truncated NS2 proteins were individually analyzed for the ability to bind ssRNA and to form VIBs. The results indicated that the carboxy terminus of the protein is involved neither in RNA binding nor in the formation of VIBs. The amino terminus of NS2 was shown to be essential for ssRNA binding but not for NS2 protein oligomerization. Point mutations that involved the substitution of various charged residues at the amino terminus of NS2 were generated and tested for the ability to bind ssRNA. The results showed that the arginines at amino acid residues 6 and 7 and the lysine at residue 4, but not the glutamic acid at residue 2, are involved in ssRNA binding.

Amino Acid Sequence↗
PubMed1994

Mutations in the muscle sodium channel gene (SCN4A) in 13 French families with hyperkalemic periodic paralysis and paramyotonia congenita: phenotype to genotype correlations and demonstration of the predominance of two mutations.

Hyperkalemic periodic paralysis (hyperPP), paramyotonia congenita (PC) and PC with myotonia permanens are closely related muscle disorders of genetic origin due to allelic mutations in the muscle sodium channel gene, SCN4A. Seven families of French origin with hyperPP were studied. Five of these had the Thr704Met mutation, but 2 families, genetically linked to SCN4A, failed to show any of the known mutations of SCN4A. Correlations between the phenotype and the genotype were made for patients with the Thr704Met mutation. All 12 patients over 30 years old with the Thr704Met mutation presented muscle weakness due to degeneration of muscle fibers in addition to periodic paralysis. Only approximately 12.5% of patients with the Thr704Met mutation presented with clinical myotonia and about 50% with hyperkalemia. One family with PC displayed the Gly1306Val mutation with a phenotype similar to the one already reported for this mutation. Five families with either PC or PC with myotonia permanens had the Thr1313Met mutation indicating that the severity of myotonia and its permanence were variable. Two mutations of SCN4A were found to be predominant in these 13 families: the Thr704Met and the Thr1313Met mutations. Only 2 families with the Thr704Met mutation and 3 families with the Thr1313Met shared the same SCN4A haplotype determined with intragenic dinucleotide repeats. Recurrent mutations of SCN4A may contribute to the predominance of these two mutations in the French population.

Adolescent↗
PubMed1994

Cognitive impairment and mortality in older community residents.

OBJECTIVE: Cognitive impairment among the elderly has been linked to mortality in studies of clinical populations. The purpose of this study was to examine the mortality risk associated with cognitive impairment among elderly populations in the community. METHODS: Cognitive impairment and other social and health factors were assessed in 1855 elderly community residents. This sample was reinterviewed periodically to assess changes in health and survival. RESULTS: At baseline 33% of the sample were mildly impaired and 8% were severely impaired. Across a 48-month observation period the survival probability was .85 for the cognitively unimpaired, .69 for the mildly impaired, and .51 for severely impaired respondents. When adjustments were made for the effects of other health and social covariates, severely impaired persons were twice as likely to die as unimpaired persons. Those who were mildly impaired were also at an increased risk. CONCLUSIONS: Other investigators have found that cognitive impairment is a significant predictor of dementia. We found that it is a significant predictor of mortality as well. Early detection of impaired cognition and attention to associated health problems could improve the quality of life of these older adults and perhaps extend their survival.

Age Factors↗
PubMed1994

Tumor oxygenation after 1) carbogen and/or perflubron emulsion administration in tumor xenografts 2) carbogen administration in patients.

This study examines the changes in tumor pO2 distribution assessed by polarography (KIMOC 6650, Eppendorf) in 1) two human tumor xenografts after carbogen inhalation with or without a perflubron (perfluorooctylbromide) emulsion (Oxygent, Alliance Pharmaceutical corp.) and in 2) human head and neck carcinomas after carbogen inhalation. Mice bearing HRT18 or NA11+ tumors were restrained and their body temperature was kept constant. Perflubron emulsion (4 ml/kg) was injected i.v. in the mice. In patients, oxygenation of the head and neck metastatic lymph nodes was assessed before and/or during carbogen exposure. The distribution of pO2 values shifted upwards during carbogen exposure in both animals and patients while the proportion of low pO2 values decreased. The maximal effect was obtained with patients after 1 to 6 minutes of carbogen exposure, but 4 patients still maintained very low pO2s. Carbogen plus 4 ml/kg perflubron emulsion was more efficient than carbogen alone for increasing hypoxic tumor pO2 in animals. If the animals data could be extrapolated to humans, then the effect of carbogen on tumor oxygenation should be increased by perflubron emulsion administration.

Administration, Inhalation↗
PubMed1994

Isolation and characterization of neurokinin A receptor cDNAs from guinea-pig lung and rabbit pulmonary artery.

cDNA clones for NK-2 receptors (NK-2R) were isolated from guinea-pig lung (GPl) and rabbit pulmonary artery (Rpa) using a polymerase chain reaction based methodology. The GPl NK-2R consists of 402 amino acids and encodes a protein with a relative molecular mass of 45,097. The Rpa NK-2R consists of 384 amino acids and encodes a protein with a relative molecular mass of 43,169. The GPl and Rpa NK-2Rs share significant amino acid sequence homology amongst themselves (90.1%), as well as with human, bovine, hamster and rat NK-2 receptors. The two receptors were stably transfected into mouse erythroleukemia cells, high-speed membranes were prepared from induced cells and their pharmacological properties examined utilizing [3H]-NKA in a receptor-binding assay. [3H]NKA bound to both NK-2Rs with high affinity (KD = 2-7 nM) and saturable (Bmax = 633-9000 fmol/mg protein) manner which was inhibited by GTP analogs. Competition experiments with agonists demonstrated identical order of potency in both NK-2Rs; NKA > [Nle10]NKA(4-10) > [beta-Ala8]NKA(4-10) > > Substance P > > > Senktide. Similarly, an identical profile for both receptors was observed with selective NK-2 antagonists: SR48,968 > MEN10,376 > > R396. The rank order of antagonist affinity is consistent with that in cloned human NK-2R and the observations of NK-2 receptor pharmacology in native human, guinea pig and rabbit tissues.

Amino Acid Sequence↗
PubMed1994

Chemical- and radiation-induced esophageal injury.

The esophageal wall can only respond to injury in a limited fashion. This article explores some of the protective mechanisms involved as well as current approaches to diagnosis and management of chemical- and radiation-induced esophageal injury.

Burns, Chemical↗
PubMed1994

[Particle state: divided solids and functionality].

Physical and physico-mechanical properties of powder particles, in the field of pharmacy, as drugs, excipients, microparticles and so on... are one of the main element in quality of dosage forms. The aim of this work is to insist on the importance of packing and rheological properties of divided solids and on his influence on compacting behaviour in drug development and industrial process, to avoid difficulties due to the variability of physical properties batch to batch. But as the physical quality of material raw is induced up to the crystallization operation, it is necessary to know, before, what use it will be done.

Elementary Particles↗
PubMed1994

Treatment of juvenile chronic myelomonocytic leukemia by allogeneic bone marrow transplantation.

Twelve of 15 patients with juvenile chronic myelomonocytic leukemia (JCMML) referred to our unit underwent allogeneic bone marrow transplantation (BMT) between 1982 and 1992. BMT was not performed in the remaining three cases because of poor overall condition in two and disease progression in one. Six patients received marrow from HLA-identical siblings after a chemotherapy conditioning regimen in five cases. BMT failed in one case. Long-term remission was achieved in three patients and two others are in remission 6 and 11 months after BMT. Remission was associated with autologous recovery in one patient and minimal mixed chimerism in another. In one patient, a first BMT procedure resulted in autologous recovery and relapse. A second transplant, with chemotherapy conditioning including TBI, was successful. BMT with marrow from a matched unrelated donor was also successful. IN contrast, BMT with marrow from mismatched related donors (five patients) failed because of graft failure and/or relapse. This single-center series indicates that HLA-identical BMT is an appropriate treatment for JCMML. However, on the basis of these results it cannot be ascertained whether chemotherapy or splenectomy are necessary prior to BMT. The best chemotherapy conditioning regimen remains to be defined, as regimens consisting exclusively of chemotherapy resulted either in long-term remission or in autologous recovery with relapse.

Antineoplastic Agents↗
PubMed1994

Isolation and pharmacological characterization of a hamster urinary bladder neurokinin A receptor cDNA.

Functional cDNA clones for hamster neurokinin-2 receptor (NK-2R) were isolated from hamster urinary bladder using a polymerase chain reaction-based methodology. The hamster NK-2R consists of 384 amino acids with a relative molecular weight of 43,418. Hamster NK-2R shares significant amino acid sequence homology with other tachykinin receptors, particularly with rat, bovine, and human NK-2R (94.3, 84.4, and 86.5%, respectively). To examine the pharmacology of cloned hamster NK-2R, we transfected mouse erythroleukemia cells with this receptor, prepared high speed membranes, and studied the receptor properties utilizing the ligand [4,5-3H-Leu9]NKA in a receptor-binding assay. For pharmacological comparison, we also transfected the human NK-2R into mouse erythroleukemia cells. [3H]NKA bound to hamster NK-2R receptor in a protein-dependent, high affinity (Kd1 = 4.14 +/- 0.31 nM), saturable (Bmax1 = 679 +/- 26 fmol/mg of protein), and highly specific manner (89 +/- 2%). A smaller population (10% density) of lower affinity receptors (Kd2 = 150 +/- 92 nM), was also observed in competition experiments. [3H]NKA bound to the human receptor with significantly higher affinity and overall greater receptor density (Kd1 = 0.37 +/- 0.11 nM, Bmax1 = 234 +/- 175 fmol/mg of protein; Kd2 = 9.0 +/- 2 nM, Bmax2 = 1989 + 990 fmol/mg of protein). [3H]NKA binding to both hamster and human receptors was enhanced greatly by divalent cations, whereas GTP analogs weakly inhibited binding to hamster receptor, but potently inhibited binding to the human receptor. Competition experiments with agonists demonstrated binding to high and low affinity states of NK-2 receptors, with identical order of potency in hamster or human NK-2R; NKA > [Nle10]NKA(4-10) > [beta-Ala8]NKA(4-10) >> substance P >>> Senktide. However, remarkable differences were observed in studies with selective NK-2 antagonists (hamster, SR48,968 > L659,877 > R396 >> MEN10,376 versus human, SR48,968 > MEN10,376 > L659,877 > R396). The rank order of antagonist affinity is consistent with the observations of NK-2 receptor pharmacology in the native tissues.

Amino Acid Sequence↗
PubMed1993

Favored and suppressed patterns of hydrophobic and nonhydrophobic amino acids in protein sequences.

Hydrophobic amino acids of the group Leu, Ile, Val, Phe, and Met (LIVFM) are distributed in favored or suppressed patterns within protein sequences. The frequencies of all five-position combinations of [symbol: see text] = LIVFM and [symbol: see text] = non-LIVFM residues were analyzed in 48 proteins of known crystallographic structure. Some motifs were strongly preferred or suppressed; e.g., [symbol: see text] was favored (z = 3.5), while [symbol: see text] was suppressed (z = -3.4). In longer patterns, [symbol: see text] followed by [symbol: see text] and one [symbol: see text] was favored ([symbol: see text], z = 5.1), while conversion of the single hydrophobic residue to a pair was not ([symbol: see text], z = 0.8). Distributions of certain non-LIVFM amino acids around [symbol: see text] positions in strongly favored patterns were also favored or disfavored (Asp, Glu, Lys, Arg, Asn, Cys, Tyr, and Pro; for each magnitude of z > 2.0). While the strongly favored pattern [symbol: see text] was found in both alpha-helical and beta-strand sequences, it associated significantly with alpha-helices (z = 3.6 for the second-position alpha-helical phi and psi angles) but not with beta-strands (z = -1.1). Certain motifs of LIVFM and non-LIVFM residues might be selected if they lead efficiently to the local nucleations hypothesized to characterize molten globule intermediates in the folding of proteins.

Amino Acid Sequence↗