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Biomedical subjects

P Thomas

Publications and source records attributed to P Thomas.

At least 19 recordsLinked to original sources
PubMed1995

The effect of transfection of the CEA gene on the metastatic behavior of the human colorectal cancer cell line MIP-101.

Carcinoembryonic antigen (CEA) has been shown to increase the metastatic potential of some human colorectal cancer cell lines. To investigate further the mechanisms involved we have produced three clones (6, 8 and 17) from the poorly differentiated human colorectal cancer cell line MIP-101 that have been transfected with the full length cDNA encoding for human carcinoembryonic antigen (CEA). They produce CEA with a mol. wt. of 180000 by Western blotting and secrete it into the culture medium. Clone 6 is a high CEA producer, clones 8 and 17 are intermediate producers. The doubling time for clone 8 was similar to that of the parent cell line while clones 6 and 17 had doubling times nearly twice that of the parent cells. These clones are tumorigenic when injected subcutaneously in nude mice are positive for CEA by immunoperoxidase staining and the mice have elevated blood levels of CEA. Clone 6 formed large aggregates in culture while clone 17 formed smaller aggregates. Clone 8 behaved like the parent cell line with rare cell/cell contact. Clones 6 and 17 also adhered to CEA coated plastic while clone 8, a neo-transfected control and the parent cell line did not. A significant increase in the incidence of hepatic tumors was observed with clone 6 (P < 0.01) and clone 17 (P < 0.02) following intrasplenic injection into nude mice. Immunohistopathology of the hepatic tumors showed strong CEA staining from clones 6 and 17 with weak staining from clone 8. The parent cell line was negative for CEA as were the neo-transfected controls. Of the neo controls none of 10 had liver colonies. Mice injected with clone 6 which developed liver metastasis had the highest plasma levels of CEA (37.3 +/- 8.8 ng/ml). We observed strong CEA staining in Kupffer cells in the normal liver adjacent to the CEA producing tumors. This study provides further evidence for the involvement of CEA in the metastatic process.

Adenocarcinoma↗
PubMed1995

Carcinoembryonic antigen and other glycoconjugates act as ligands for galectin-3 in human colon carcinoma cells.

Galectin-1 and galectin-3, galactoside-binding lectins with molecular weights of M(r) 14,500 and 31,000, respectively, are expressed in normal and malignant cells and have been implicated in regulation of cell growth, adhesion, and metastasis. We analyzed the expression of galectins in 21 cultured human colon carcinoma cell lines by immunoblotting. Galectin-1 was detected in only 7, whereas galectin-3 was found in 20 of the cell lines. KM12 cells, which express only galectin-3, were used to isolate this lectin by affinity chromatography, and the purified lectin was used to identify complementary glycoconjugates by blotting. Galectin-3 was shown to bind to human laminin, carcinoembryonic antigen, and lysosome-associated membrane glycoproteins, which are involved in cell adhesion. Galectin-3 was localized on the KM12 cell surface and colocalized with carcinoembryonic antigen. Several endogenous glycoproteins and cell surface proteins of molecular weights in the range M(r) 58,000 to > 200,000, including carcinoembryonic antigen and lysosome-associated membrane glycoproteins, were identified as galectin-3 ligands by coimmunoprecipitation with and affinity chromatography on immobilized galectin-3. These data demonstrate that galectin-3 interacts with several adhesion molecules and suggest that this lectin may have a role in human colon carcinoma cell adhesion.

Antigens, CD↗
PubMed1995

[Intraoperative anaphylaxis due to natural latex in a 3-year-old boy].

A nearly three-year-old boy with a genitourinary malformation, which had already been operated on several times, developed generalized urticaria, facial swelling and bronchospasm within 15 minutes of the induction of anaesthesia. The signs quickly responded to the administration of methylprednisolone (32 mg), clemastine (10 mg) and ranitidine (25 mg). There was a twofold positive immediate reaction in the prick test to natural rubber latex (white and brown), and specific IgE was demonstrated against the latex (2.58 kU/l). On the other hand, prick tests with perioperatively administered drugs and an oral provocation test with an antibiotic administered in the perioperative period were negative. The history of itching caused by an indwelling bladder catheter, vesicles on the lips after sucking on a rubber dummy and the described findings on examination both point to the natural rubber latex as the responsible allergen. No complications occurred three months later during a surgical intervention under administration of steroids and H1- and H2-receptor antagonists, as well as avoidance of materials made of natural rubber latex.

Anaphylaxis↗
PubMed1995

[Perforated duodenal ulcer: subtotal anterior linear and posterior tuberous gastrectomy].

OBJECTIVE: To evaluate emergency surgery procedures for perforated duodenal ulcers. METHODS: Emergency surgery was performed for perforated duodenal ulcers in 25 patients (19 males and 6 females) with a mean age of 36 +/- 15 years. The procedure consisted of simple closure followed by anterior and partial posterior linear gastrectomy using a stapling device. There were 16 patients who smoked, 11 who drank and smoked, 3 who were under treatment with non-corticosteroid anti-inflammatory agents, 2 who had a history of other disease (myocardial infarction and arteritis) and 4 who were in septic shock. RESULTS: The delay in closure of perforation was less than 6 hours in 17 cases. Peritoneal leakage was confined to the supramesocolic level in 19 cases. The mean follow-up was 14 +/- 2 months with endoscopic control at 12 months. One recurrence (4%) was observed at 8 months. One patient died. Morbidity occurred in 7 patients (28%); epigastric bloating in 5 cases, subphrenic abscess in 1, abscess of the stomach wall in 1 and oesophageal reflux treated without surgery in 1. The mean duration of hospitalization was 13 +/- 3 days.

Adult↗
PubMed1995

Expression, purification and characterization of 1-aminocyclopropane-1-carboxylate oxidase from tomato in Escherichia coli.

1-Aminocyclopropane-1-carboxylate (ACC) oxidase catalyses the final step in the biosynthesis of the plant hormone ethylene. The successful overexpression and characterization of active ACC oxidase from tomato has been achieved. PCR was used to insert the corrected cDNA coding for the tomato ACC oxidase into the pET-11a expression vector. Cloning of the resultant construct in Escherichia coli BL21(DE3)pLysE gave transformants which expressed ACC oxidase at levels greater than 30% of soluble protein under optimized conditions. When induced by addition of isopropyl-beta-D-thiogalactopyranoside (IPTG) at 37 degrees C the ACC oxidase expressed was less soluble and less active than when induced at 27 degrees C. The enzyme was purified to near homogeneity by a three-step chromatographic procedure. The specific activity of the purified recombinant ACC oxidase was typically 1.3-1.9 mol of ethylene/mol of enzyme per min, higher than values reported for native enzyme. Like the native enzyme it displayed a requirement for ferrous iron and ascorbate, and CO2 was an activator. The ability to discriminate between racemic diastereomers of 1-amino-2-ethyl cyclopropane-1-carboxylic acid was demonstrated. The enzyme was found to have a loose specificity for ascorbate, showing apparent preference for D-ascorbate and 5,6-O-isopropylidene L-ascorbate rather than L-ascorbate. The addition of catalase, dithiothreitol and BSA to incubation mixtures all resulted in significant increases in activity. When treated with diethylpyrocarbonate (DEPC) under mildly acidic conditions, the enzyme rapidly lost activity. Comparison of the rate of inactivation with the increase in absorbance at 240 nm gave results consistent with the modification of two to three histidine residues at the active site, although the possibility of additional modification of other nucleophilic residues cannot be excluded. Inactivation was largely prevented by the addition of substrates and ferrous iron, implying that DEPC treatment results in the modification of active-site histidines, which act as ligands for ferrous iron. CO2 offered no protection against DEPC inactivation, either in the absence or presence of substrates and/or ferrous iron.

Amino Acid Oxidoreductases↗
PubMed1995

The implications of age of onset for delinquency risk. II: Longitudinal data.

The role of age of onset in the level of involvement in delinquent behavior as marked by seriousness and chronicity of involvement continues to draw extensive attention from researchers. This issue bears on some of the key causal contentions about the dynamism of involvement and the validity of a developmental model of antisocial behavior risk. Five waves of the National Youth Survey were utilized here to determine if, among a nationally representative sample, there was evidence of onset age influence on later involvement. Results suggest that early onset (before age 12) relates to higher rates of more serious acts over a longer period of time for boys and girls. Overall, the results suggest support for early onset spurring on later involvement, but the contribution is small once psychosocial predictors are considered. Onset age seems most important in understanding involvement in serious crime over several years. Involvement is explained best by peer variables for males and school and family variables for females. Onset age is explained by a wider range of variables than involvement and there is greater similarity of the psychosocial variables that explain onset for both genders. The interaction of involvement and predictors was noted, suggesting a dynamic model of risk. Implications for prediction and prevention are discussed.

Adolescent↗
PubMed1995

[The tuberculid concept from the current viewpoint].

The concept of tuberculid was introduced by Darier in 1896. In contrast to "true" cutaneous tuberculosis, properties of the tuberculids were explained by an hyperergic response to myobacteria or their fragments released from a different site of manifest or passed tuberculous infection. Key features include a strongly positive tuberculin skin test, evidence of concomitant manifest or past tuberculosis, and prompt response to antituberculous therapy. The inability to culture M. tuberculosis or to demonstrate it microscopically from lesional biopsies, together with reports on tuberculid-like eruptions after BCG vaccination, supports this concept. Clinical manifestations are lichen scrophulosorum, papulo-necrotic tuberculids and erythema induratum of Bazin. The existence of tuberculids has been questioned, however, because the clinical and histological appearances are not always specific. An increasing number of case reports on tuberculids, new immunological tests and molecular biology-based techniques for the detection of mycobacteria have shed new light on the tuberculid concept.

Diagnosis, Differential↗
PubMed1995

The nature and source of the head injuries sustained by restrained front-seat car occupants in frontal collisions.

The paper examines the types of head injury sustained by restrained front-seat car occupants in frontal collisions. Injuries are classified into soft tissue, diffuse and focal brain injuries and facial bone or skull fractures. Survivors seldom sustain focal injuries although these are common amongst fatalities. The contact sources within the car are described. Intruding structures and high crash severities are typically associated with high rates of the more severe injuries from steering wheel contact, although some are sustained with intrusion below 11 cm. Low-speed impact testing on nondeployed airbag-equipped wheels is suggested. Toughened glass windscreens are overrepresented amongst those sustaining injuries from glazing materials. Test procedures to reduce injuries from pillar contacts should take account of the dynamic effects of an intruding pillar. Contacts with objects outside the car caused higher rates of severe fractures and brain injury; however, the total numbers are greater from interior contacts.

Abbreviated Injury Scale↗
PubMed1995

Characterization of a progestogen receptor in the ovary of the spotted seatrout, Cynoscion nebulosus.

A nuclear progestogen receptor was identified in the ovary of the spotted seatrout, Cynoscion nebulosus. A single class of high-affinity, low-capacity cytoplasmic binding sites for 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17 alpha,20 beta-P) was characterized by saturation and Scatchard analyses (KD = 1.89 +/- 0.61 nM, Bmax = 1.80 +/- 0.63 pmol/g ovary, n = 4), as well as by one-point assay (Bmax = 1.41 +/- 0.26 pmol/g ovary, n = 12). Analysis of the binding kinetics indicated a fairly rapid association rate (T1/2 = 72 +/- 10.2 min) and a slightly slower dissociation rate (T1/2 = 99 +/- 9.4 min). Competition studies revealed that several steroids exhibited the same range of affinity (17 alpha, 20 beta-P > 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one (20 beta-S) > 11-deoxycorticosterone > progesterone) while others displayed an order of magnitude less affinity (17 alpha-hydroxy-4-pregnen-3-one > pregnenolone > 11-deoxycortisol > testosterone). No displacement was found with 1000-fold excess estradiol-17 beta or cortisol. Binding activity was also present within the testis, but not in the brain, gill, muscle, or plasma. Nuclear binding was detected by DNA-cellulose column chromatography and was inhibited by the addition of molybdate, a characteristic of nuclear steroid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Glutathione plays a key role in the depigmenting and melanocytotoxic action of N-acetyl-4-S-cysteaminylphenol in black and yellow hair follicles.

This study examined the effect of glutathione on the in vivo depigmenting potency of N-acetyl-4-S-cysteaminylphenol (N-acetyl-4-S-CAP) in black and yellow mice after multiple intraperitoneal injections on 10 consecutive days. In black mice (C57BL/6J, a/a), N-acetyl-4-S-CAP showed dose-dependent depigmenting potency (0.5, 1.0, and 2.0 mmol/kg), which was in parallel to the tissue eumelanin content (98%, 28%, and 3% of controls, respectively) and to the tissue glutathione content (94%, 85%, and 76%, respectively). In lethal yellow mice (C57BL/6J, Ay/a), only a dose of 2.0 mmol/kg showed the color change of hair to dark, not to white as seen in black mice. This was reflected by the decrease of pheomelanin content (56%) and the increase of eumelanin content (28% of black mice). The simultaneous administration of N-acetyl-cysteine, which up-regulated glutathione content, completely abolished the depigmenting potency of N-acetyl-4-S-CAP, whereas administration of buthionine sulfoximine, which depleted the tissue glutathione content, enhanced the depigmenting potency of N-acetyl-4-S-CAP in black hair. In yellow mice, the darkening of hair follicles by 2.0 mmol/kg of N-acetyl-4-S-CAP was completely abolished by the combined administration of N-acetyl-cysteine, with the resulting hair color the same as in controls, whereas combined administration with buthionine sulfoximine caused some whitening of yellow hair follicles. Our data indicate that the tissue content of glutathione regulates melanocytotoxicity and depigmenting potency of N-acetyl-4-S-CAP and that this alteration of glutathione content may switch the melanogenesis type from pheomelanin to eumelanin.

Animals↗
PubMed1995

Tryptase and histamine release due to a sting challenge in bee venom allergic patients treated successfully or unsuccessfully with hyposensitization.

BACKGROUND: Hyposensitization with been venom leads to full protection in most, but not all patients with IgE-mediated systemic reactions to bee stings. OBJECTIVE: To determine the relationship of clinical reactivity to the release of mediators and to changes of antibody concentrations in the peripheral circulation at a bee sting challenge test. METHODS: Blood was sampled before (1 min) and at 15, 60 and 180 min after a sting challenge from 19 patients on hyposensitization. Of these six still reacted and 13 were protected. Histamine, mast cell tryptase, bee venom-specific IgE and IgG in the serum, and histamine release from peripheral blood leucocytes (PBL) upon exposure to bee venom were determined. RESULTS: Tryptase above the detection level was found only at 15 (60) min in 4/6 (1/6) patients who reacted. After the sting challenge there was a significant increase of the histamine levels in patients who reacted at 15 min (P < 0.05) and in patients who did react at 60 and 180 min (P < 0.01). The total histamine content of PBL was significantly decreased after 15 and 60 min in patients who reacted (P < 0.01) and in those that did not (P < 0.05). Bee venom-induced histamine release was significantly reduced in patients reacting and those that did not at 15 min (P < 0.05), and was significantly decreased in reactors also at 60 and 180 min (P < 0.05/0.01). Specific IgG antibodies showed a minor decrease (P < 0.05) after the sting challenge in both groups, whereas specific IgE did not change significantly. CONCLUSION: These results indicate that bee venom anaphylaxis is associated with the release of mediators from both mast cells as well as basophils. Successful hyposensitization does not induce a state of immunological non-reactivity, but rather alters the magnitude and the pattern of mediator release.

Adult↗
PubMed1995

Opercular myoclonic-anarthric status epilepticus.

We report 3 cases of opercular myoclonic status epilepticus (OMASE), characterized by fluctuating cortical dysarthria without true aphasia associated with epileptic myoclonus involving bilaterally the glossopharyngeal musculature. In this syndrome, the inferior rolandic area of either one or the other hemisphere is involved by an epileptogenic lesion of various etiology. Ictally, clonic expression was consistent with epilepsia partialis continua (EPC) and bilaterally and symmetrically involved palatal muscles (cases 1-3), tongue (cases 2 and 3), lips and chin (case 3), and inferior jaw (case 1) due to bilateral projections of the inferior corticonuclear pathways. Postictally, the main clinical sign was pseudobulbar palsy, consistent with Todd's palsy. In our cases, OMASE was either of vascular (cases 1 and 2) or tumoral origin (case 3). In adulthood, early recognition of OMASE, although nonspecific, may be important for early management of carotid occlusive disease because it usually indicates an acute opercular infarction.

Adult↗