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Biomedical subjects

S Lambert

Publications and source records attributed to S Lambert.

At least 37 records · Page 2Linked to original sources
PubMed1990

cDNA sequence for human erythrocyte ankyrin.

The cDNA for human erythrocyte ankyrin has been isolated from a series of overlapping clones obtained from a reticulocyte cDNA library. The composite cDNA sequence has a large open reading frame of 5636 base pairs (bp) with the complete coding sequence for a polypeptide of 1879 amino acids with a predicted molecular mass of 206 kDa. The derived amino acid sequence contained 194 residues that were identical to those obtained by direct amino acid sequencing of 11 ankyrin proteolytic peptides. The primary sequence contained 23 highly homologous repeat units of 33 amino acids within the 90-kDa band 3 binding domain. Two cDNA clones showed evidence of apparent mRNA processing, resulting in the deletions of 486 bp and 135 bp, respectively. The 486-bp deletion resulted in the removal of a 16-kDa highly acidic peptide, and the smaller deletion had the effect of altering the COOH terminus of the molecule. Radiolabeled ankyrin cDNAs recognized two erythroid message sizes by RNA blot analysis, one of which was predominantly associated with early erythroid cell types. An ankyrin message was also observed in RNA from the human cerebellum by the same method. The ankyrin gene is assigned to chromosome 8 using genomic DNA from a panel of sorted human chromosomes.

Amino Acid Sequence↗
PubMed1989

[Odontogenic keratocysts. Review of the literature and presentation of three clinical cases with different surgical approaches].

The odontogenic keratocyst is an intra-osseous cystic lesion which generally affects the posterior part of the mandible and is characterized by the presence of a keratinized epithelium. Being asymptomatic, it is usually detected through a routine radiographic exam and it is considered to be an important lesion because of its agressiveness and its high recurrence rate. Surgery is the recommended treatment and the mode of management should take into account the agressiveness of the lesion while trying to preserve maximal anatomical and functional integrity for the patient. This paper reviews the recent literature on odontogenic keratocysts and reports our experience with three cases successfully managed in three different ways: marsupialization, decompression followed by enucleation with primary closure and finally by enucleation with packing for secondary intention healing.

Adult↗
PubMed1988

Patterns of alcohol use and psychiatric inpatient admissions.

The role of alcohol problems in psychiatric inpatient hospital admissions is not fully reflected in diagnostic statistics. A model is presented to guide the design and aid the interpretation of epidemiological research into the relationships between alcohol use and psychiatric disorder. The difficulties encountered in evaluating the role of alcohol in hospitalizations are discussed. Our preliminary research suggests that not enough attention has been paid to self-imposed abstinence from alcohol as a precipitant of symptoms and a precursor to hospitalization.

Alcohol Drinking↗
PubMed1988

Epidermal DR+T6- dendritic cells in inflammatory skin diseases.

T lymphocyte and dendritic cell subpopulations were counted in three biopsies each of endogenous eczema and pityriasis rosea and two of lichen planus and compared with previous findings in psoriatic lesions. In common with psoriasis, proportionately more CD4 T cells than CD8 T cells were DR+ in both epidermis and dermis of all lesions. In addition, total numbers of epidermal dendritic cells were significantly increased in endogenous eczema and pityriasis rosea, and variably in lichen planus lesions. Interestingly, a DR+T6- subpopulation of dendritic cells was present in varying proportions in all three skin lesion types. Electron microscopy of DR+T6- dendritic cells from psoriatic lesions, using an immunogold staining technique, showed the cells to be of the Langerhans' cell lineage. DR+T6- dendritic cells are a subpopulation of Langerhans' cells which are not specific to psoriasis, but present in the lesions of other benign, inflammatory skin conditions in which CD4 T cells are preferentially activated.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

A prospective study of the Koebner reaction and T lymphocytes in uninvolved psoriatic skin.

T lymphocyte and dendritic cell subpopulations were counted in untraumatized, uninvolved skin of 27 patients with psoriasis. Eight of the patients proved to be Koebner-positive, as determined by tape stripping and punch biopsy, and 19 Koebner-negative. In the epidermis the CD4/CD8 T cell ratio was significantly higher in the Koebner-positive vis-à-vis Koebner-negative patients (median CD4/CD8 = 1.68 and 0.75, respectively: p less than 0.05). This resulted from a small increase in CD4 and a larger decrease in CD8 epidermal T cells in the Koebner-positive group. However, numbers of epidermal dendritic cells did not differ significantly between the two groups. In the dermis the CD4/CD8 T cell ratio was also higher in the Koebner-positive than in Koebner-negative patients (median of 3.56 and 2.57, respectively). These findings demonstrate that the tendency of uninvolved skin of psoriatic individuals to become lesional after trauma is associated with a predominance of CD4 over CD8 T cells in the epidermis.

Dendritic Cells↗
PubMed1988

A molecular study of heterozygous protein 4.1 deficiency in hereditary elliptocytosis.

Genomic DNA from five kindreds and two individuals with hereditary elliptocytosis [HE(4.1+)] and a partial deficiency of protein 4.1 [HE(4.1+)] was extracted and probed with a cDNA for protein 4.1. When using a fragment of the cDNA that encompassed the coding region of the gene, two restriction fragment length polymorphisms segregating with protein 4.1 deficiency were found in one kindred when using the enzymes BgIII and PvuII but were not seen in the other HE(4.1+) subjects or in 20 random control individuals. DNA digested with three other enzymes (HindIII, EcoRI, TaqI) produced restriction patterns similar to controls. The unique BgIII and PvuII polymorphisms probably reflect a rearrangement of the coding region of the protein 4.1 gene as the underlying cause of the partial protein 4.1 deficiency in this family. A less likely possibility is that these polymorphisms represent coincidental single base changes unrelated to the primary gene defect.

Blotting, Southern↗
PubMed1987

Partial deficiency of protein 4.1 in hereditary elliptocytosis.

Protein 4.1, an important component of the red cell membrane skeleton, was quantitated relative to protein 3 after sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of membranes isolated from red cells of members of 14 kindreds with hereditary elliptocytosis (HE) who reside in South Africa. A partial deficiency of protein 4.1 (mean 30% reduction) was inherited in autosomal dominant fashion in five white kindreds giving a frequency of 0.36 of HE families studied. Immunoblots of membrane proteins separated by SDS-PAGE and probed with a monoclonal antibody to protein 4.1 did not reveal any proteolytic fragments in the 4.1-deficient subjects that could account for the reduction of this protein. These studies draw attention to the relatively high frequency of this condition as a cause of HE in white subjects in this country.

Blood Proteins↗
PubMed1987

The effects of cyclosporin A on T lymphocyte and dendritic cell sub-populations in psoriasis.

Sequential skin biopsies from six patients with severe psoriasis were studied during treatment with cyclosporin. Four of the patients cleared completely and the remaining two showed a marked improvement. A subset of dendritic cells, HLA-DR+ but lacking the T6 antigen characteristically expressed by Langerhans cells (DR+ 6-), was observed in lesional epidermis. They disappeared during treatment, before clinical improvement was apparent and at a rate which correlated with clearance of psoriasis. These cells were not found in normal or uninvolved psoriatic epidermis and their number in lesional skin appeared to be related to the clinical severity of the disease. Total numbers of CD4 and CD8, and HLA-DR+ CD8 T cells were substantially reduced in both epidermis and dermis prior to clinical improvement. In contrast, there was generally no decrease in the number of HLA-DR+ CD4 T cells in the epidermis during resolution, whereas these cells were reduced by an average of 68% in the dermis. The beneficial effects of cyclosporin in psoriasis further support the hypothesis that T cells play a central role in the pathogenesis of psoriasis. The cellular changes observed in the skin during cyclosporin treatment may help to elucidate the effects of this drug on immunoregulatory mechanisms in man.

Adult↗
PubMed1987

Infectivity and antigenicity reduction rates of human rotavirus strain Wa in fresh waters.

The rates of inactivation of human rotavirus type 2 (strain Wa) (HRV-Wa) and poliovirus type 1 (strain CHAT) were compared in polluted waters (creek water and secondary effluent before chlorination) and nonpolluted waters (lake water, groundwater, and chlorinated tap water). Viral infectivity titers were determined by plaque assays, while HRV-Wa antigenicity also was monitored by an enzyme-linked immunosorbent assay. Both viruses persisted longest in lake water and shortest in tap water. The actual inactivation times (i.e., times required for two-log10 reductions of initial viral titers) for the two viruses were significantly different in all waters except tap water. With the exception of the groundwater and secondary effluent results, the HRV-Wa inactivation times in the fresh waters tested were significantly different. Owing perhaps to aggregation, HRV-Wa appeared less susceptible to the effects of chlorine than previously reported for this virus and for the simian rotavirus SA11. HRV-Wa displayed prolonged survival in lake water and groundwater exceeding that previously reported for the SA11 virus. The HRV-Wa infectivity reduction rate (ki) was significantly correlated with the water pH (i.e., as pH increased, ki increased). The water pH may have influenced viral aggregation and thereby HRV-Wa susceptibility to other virucidal factors in the water. Enzyme-linked immunosorbent assay results showed similar inactivation patterns with the most significant reduction in HRV-Wa antigenicity occurring in polluted waters and tap water. In all waters, particularly tap water, infectivity declined at a faster rate than antigenicity. It is proposed that HRV-Wa can be used as a model for future studies of rotaviral persistence in the aquatic environment.

Analysis of Variance↗
PubMed1987

A new variant of the alpha subunit of spectrin in hereditary elliptocytosis.

A kindred is described in which two brothers with a poikilocytic variant of hereditary elliptocytosis (HE) were found to have a defect of spectrin dimer association and a decreased spectrin-band 3 ratio. Two-dimensional gel electrophoresis of limited tryptic digests of their spectrin revealed decreased amounts of the alpha I domain when compared with control digests and the appearance of two major peptides with mol wts of 43,000 and 42,000 and isoelectric points (5.75 to 5.85) more basic than the alpha I domain. Tryptic digests of spectrin from the asymptomatic mother of the two brothers were normal. Immunoblots of the two-dimensional gels using an antiserum to the alpha I domain revealed that the 43,000- and 42,000-dalton peptides were derived from the alpha I domain, along with a series of lower mol wt peptides, some of which were below the detection limits of Coomassie blue-stained gels. Limit chymotryptic maps of 125I-labeled tryptic peptides confirmed that the 43,000- and 42,000-dalton peptides were derived from the alpha I domain. This kindred represents a new structural variant of spectrin in HE in that the major abnormal tryptic peptides derived from the alpha I domain have lower mol wts and more basic isoelectric points than hitherto described.

Adult↗
PubMed1986

Studies on the structural polymorphism of the alpha-II domain of human erythrocyte spectrin.

Following restricted tryptic digestion at 4 degrees C, a structural polymorphism affecting the alpha-chain of human spectrin, the major erythrocyte membrane skeleton protein, has recently been described in American blacks (Knowles, W.J., Bologna, M.L., Chasis, J.A., Marchesi, S.L. and Marchesi, V.T. (1984) J. Clin. Invest 73, 973-979). Four variants affecting the alpha-II domain or its tryptic products have been characterized, depending on changes in molecular weight and/or isoelectric point. One variant of the alpha-II domain (Type 2) shows an increase in apparent molecular weight and basic shift in pI. It contains a limit chymotryptic peptide showing a change in chromatographic mobility on two-dimensional electrophoresis which is thought to reflect a sequence alteration associated with the increase in apparent molecular weight. We find that this altered limit chymotryptic peptide is not unique to the Type 2 variant, but is also present in a variant (Type 4) showing only the same basic shift in pI as the Type 2 variant. It is not found in a variant (Type 3) showing only an increase in apparent molecular weight. The most likely explanation for these findings is that the altered limit chymotryptic peptide common to both the Type 2 and Type 4 variants is responsible for the change in isoelectric point which is common to both these variants. An as yet unidentified change elsewhere in the polypeptide chain must be responsible for the observed alteration in molecular weight of the Types 2 and 3 variants.

Electrophoresis, Polyacrylamide Gel↗
PubMed1985

Developmental follow-up of long-term infant tracheostomy: a preliminary report.

In a retrospective study, medical records of a randomly selected sample of all infants less than 13 months old with tracheostomy of at least 1 month's duration were reviewed with respect to medical, demographic, and perinatal variables. Standardized outcome measures were used to document physical, cognitive, linguistic, and emotional development in a cross-sectional follow-up of all tracheostomized infants who were without primary mental retardation or neurological and physical handicap. The total sample of tracheostomized infants tended to be white, male, and premature, with moderate to severe medical illness in the perinatal period. There was a high rate of mortality and morbidity, with the majority of survivors presenting with multiple physical and mental handicaps. Follow-up of survivors without other major handicapping conditions suggested that long-term infant tracheostomy may be associated with impaired physical and emotional development, even when cognitive and language development are within normal limits. Pediatricians should be aware of the complex nature of this handicapping condition in order to coordinate appropriate interdisciplinary management.

Birth Weight↗
PubMed1984

The surface roughness and gloss of composites.

The contrast gloss and the average roughness were measured for four commercial composite filling materials. Using a factorial design, each material was subjected to four available finishing methods. A significant difference was found in the contrast gloss among finishing methods, and a significant linear regression is given which relates the inverse of the contrast gloss to the average roughness. Surface gloss is proposed as playing a major role in the esthetic appearance of composite restorations.

Composite Resins↗