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Biomedical subjects

S Lambert

Publications and source records attributed to S Lambert.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1978

Poppers, a new recreational drug craze.

The study was conducted to obtain information on the recreational use of the vasodilators (RVs) amyl nitrite and butyl nitrite in Toronto. The results of 70 interviews (40 complete) indicate that sniffing these RVs gives a 'high' lasting from a few seconds to a few minutes with headache being the most common side effect. None of the more serious side effects mentioned in the literature were reported. RVs are used chiefly in conjunction with sexual activities and dancing. Their use is currently a craze amongst the male homosexual population.

Adult↗
PubMedDate not supplied

Natural rubber latex allergy: spectrum, diagnostic approach, and therapy.

Latex allergy has reached epidemic proportions in the United States and is increasingly recognized as a significant contributor to morbidity and mortality during medical and surgical procedures. Ultimately, many of the affected patients with recognized latex sensitivity and those who are not yet diagnosed will receive treatment for their allergic reactions to latex in emergency departments. Consequently, emergency physicians must have a comprehensive understanding of the etiology, epidemiology, pathogenesis, treatment, and management of these challenging patients. Groups at high risk include spina bifida cystica patients, health care workers, latex industry workers, specific food-allergy patients, and patients with a history of atopy or multiple surgical procedures. Sensitization to latex antigens is commonly encountered in health care workers wearing latex gloves with high latex allergen concentrations and in workers using powdered latex surgical gloves. Exposure to air-borne allergens and water-soluble IgE reactive latex antigens from natural rubber latex products in sensitized individuals can result in type I (immediate) hypersensitivity reactions. Clinical manifestations include contact urticaria, dermatitis, allergic rhinitis, conjunctivitis, asthma, angioedema, and anaphylaxis. Diagnostic tools include serological assays and skin prick testing. At present, latex avoidance is the only available treatment and is the key to preventing allergic reactions in latex-sensitized individuals. Health care worker sensitization to latex antigens in natural rubber products is becoming an increasing contributor to workers' liability and disability claims. Specific action can be taken to reduce occupational and patient exposure to latex antigens.

Anaphylaxis↗
PubMedDate not supplied

Operative management of the stiff elbow: sequential arthrolysis based on a transhumeral approach.

Between December 1990 and September 1993, 26 consecutive patients (27 elbows) were treated for elbow contractures. We used a modified transhumeral approach supplemented by a limited lateral approach with or without a limited medial approach according to the correction gained after each step of the procedure. Eleven posttraumatic, 6 degenerative, and 10 miscellaneous contractures were evaluated. The mean follow-up was 30 months. Statistically significant improvement in the range of motion was obtained for all groups of patients; the mean flexion-extension arc of motion increased from 66 degrees to 100 degrees for the posttraumatic contractures, from 79 degrees to 102 degrees for the degenerative contractures, and from 85 degrees to 121 degrees for a miscellaneous group of contractures. Relief of pain was not an issue in the posttraumatic group; it was not significant for the degenerative group but was significant for the miscellaneous group. Flexion and extension force were maintained, and no joint was made unstable. Complications included three transient ulnar neuropathies and one tardy ulnar nerve palsy. The technique presented offers the advantage of virtually unlimited exposure of the joint in a stepwise manner, dictated by the intraoperative assessment of joint motion combined with preservation of the medial and lateral collateral ligament complexes and all relevant muscle insertions and origins. The concept is applicable to contractures of differing cause and can be adapted to the specific needs of the patient.

Adolescent↗
PubMedDate not supplied

Physiological roles of axonal ankyrins in survival of premyelinated axons and localization of voltage-gated sodium channels.

440 kD ankyrin-B and 480/270 kD ankyrin-G are membrane skeletal proteins with closely related biochemical properties yet distinctive physiological roles in axons. These proteins associate with spectrin-actin networks and also bind to integral membrane proteins including the L1 CAM family of cell adhesion molecules and voltage-gated sodium channels. 440 kD ankyrin-B is expressed with L1 in premyelinated axon tracts, and is essential for survival of these axons, at least in the case of the optic nerve. 440 ankyrin-B may collaborate with L1 in transcellular structures that mediate axon fasciculation and mechanically stabilize axon bundles, although these proteins may also be involved in axon pathfinding. Ankyrin-B (-/-) mice exhibit loss of L1 from premyelinated axon tracts and a similar, although much more severe, phenotype to L1 (-/-) mice and humans with L1 mutations. Ankyrin-B and L1 thus are candidates to collaborate in the same structural pathway and defects in this pathway can lead to nervous system malformations and mental retardation. 480/270 kD ankyrin-G are highly concentrated along with the L1CAM family members neurofascin and NrCAM at nodes of Ranvier and axon initial segments. Voltage-gated sodium channels bind directly to ankyrins, and are likely to associate in a ternary complex containing neurofascin/NrCAM, and ankyrin-G. Mice with ankyrin-G expression abolished in the cerebellum exhibit loss of ability of Purkinje neurons to fire action potentials, as well as loss of restriction of neurofascin/NrCAM to axon initial segments. Ankyrin-G thus is a key component in assembly of functional components of the axon initial segment and possibly the node of Ranvier.

Animals↗