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Biomedical subjects

S Adam

Publications and source records attributed to S Adam.

At least 19 recordsLinked to original sources
PubMed1999

Age-dependent altered proportions in subpopulations of tonsillar lymphocytes.

Age-related changes in functional subsets of lymphocytes may influence the potential to build up immune responses. In particular, the capacity of tonsillar lymphocytes to counter infections may be altered during ageing. In order to address this question we investigated the proportional distribution of several subsets of tonsillar T and B cells with regard to ageing. Tonsils were derived from 119 patients between 2 and 65 years of age. Lymphocyte subsets were monitored by three-colour fluorescence of relevant CD markers in flow cytometry. As a general tendency the percentage of CD3+ T cells steadily increased whereas that of CD19+ B cells decreased at the same time. No significant differences were observed between lymphocytes of patients with and without inflammatory history of the tonsils. The percentage of CD8+ T cells declined whereas that of CD4+ T cells increased during the same time span. CD45RA+ T cells increased during the first two decades of life and gradually decreased thereafter. In contrast, CD45RO+ T cells showed an opposite trend. No differences were seen in the population of CD3-/CD56+ natural killer (NK) cells. The mature B cell marker CD40 showed no significant changes during ageing. However, CD38+ B cells, representing B cells of late maturation stages, dramatically declined up to the age of 65. In a similar manner the CD5+ subpopulation of B cells decreased during ageing. Substantial changes in major tonsillar T and B cell populations as shown in this study may have an impact on the ageing process of the immune system.

Adolescent↗
PubMed1998

The putative cofactor TIF1alpha is a protein kinase that is hyperphosphorylated upon interaction with liganded nuclear receptors.

Ligand-induced gene activation by nuclear receptors (NRs) is a complex process requiring dissociation of corepressors and recruitment of coactivators. The putative transcriptional intermediary factor TIF1alpha has been previously characterized as a nuclear protein that interacts directly with the AF-2 ligand-dependent activating domain present in the ligand-binding domain of numerous steroid and nonsteroid receptors, including the estrogen (ERalpha) and retinoid X (RXRalpha) receptors. We report here that TIF1alpha is both a phosphoprotein and a protein kinase. TIF1alpha coexpressed in COS-1 cells with RXRalpha or ERalpha is phosphorylated and becomes hyperphosphorylated upon ligand treatment. This hyperphosphorylation requires the binding of TIF1alpha to transcriptionally active NRs since it is prevented by mutations either in the core (alpha-helix 12 of the ligand-binding domain) of the AF-2 activating domains of RXRalpha and ERalpha or in the NR box of TIF1alpha that are known to prevent TIF1alpha-NR interactions. Thus, TIF1alpha is a phosphoprotein that undergoes ligand-dependent hyperphosphorylation as a consequence of nuclear receptor binding. We further show that purified recombinant TIF1alpha possesses intrinsic kinase activity and that, in addition to autophosphorylation, TIF1alpha selectively phosphorylates the transcription factors TFIIEalpha, TAFII28, and TAFII55 in vitro. These latter results raise the possibility that TIF1alpha may act, at least in part, by phosphorylating and modifying the activity of components of the transcriptional machinery.

Animals↗
PubMed1998

Wearable microdialysis system for continuous in vivo monitoring of glucose.

We developed a new system to monitor glucose continuously in vivo. The miniaturised system is very easy to handle and was optimised to a resource-saving working modus. Sampling was performed by means of a biocompatible microdialysis needle probe inserted into the subcutaneous tissue. During glucose tolerance tests the results of our monitoring system were correlated with the glucose level of the venous blood stream. A comparison according to the procedure known as 'error grid analysis' provided an excellent correlation between the two completely independent analyses systems with the reference determination results. All values obtained with our systems were clinically correct or at least clinically acceptable.

Blood Glucose Self-Monitoring↗
PubMed1998

Blood compatible polymers in intensive care units: state of the art and current aspects of biomaterials research.

The use of artificial organs in cases of acute renal failure, acute respiratory distress syndrome (ARDS) and multiorgan dysfunction syndrome (MODS) has lead to a significant reduction of mortality. However, the interaction between body and biomaterials results in the activation of the coagulation system and in the induction of systemic inflammatory response syndrome. The necessary anticoagulation may be contraindicated and may even further increase the risk for the patient. This article evaluates the currently applied polymeric materials used in intensive care units (ICU) and gives a possible outlook into future developments. It is emphasized that systematic interdisciplinary research of physicians and biomaterial scientists is essential for the successful development of new polymers with improved biocompatibility. For this purpose a brief overview of analytical techniques for surface characterization is given, and future developments to a fully biocompatible polymer are described.

Artificial Organs↗
PubMed1998

Transport of macromolecules between the nucleus and the cytoplasm.

Nuclear transport is an energy-dependent process mediated by saturable receptors. Import and export receptors are thought to recognize and bind to nuclear localization signals or nuclear export signals, respectively, in the transported molecules. The receptor-substrate interaction can be direct or mediated by an additional adapter protein. The transport receptors dock their cargoes to the nuclear pore complexes (NPC) and facilitate their translocation through the NPC. After delivering their cargoes, the receptors are recycled to initiate additional rounds of transport. Because a transport event for a cargo molecule is unidirectional, the transport receptors engage in asymmetric cycles of translocation across the NPC. The GTPase Ran acts as a molecular switch for receptor-cargo interaction and imparts directionality to the transport process. Recently, the combined use of different in vitro and in vivo approaches has led to the characterization of novel import and export signals and to the identification of the first nuclear import and export receptors.

Biological Transport↗
PubMed1997

Binding of fibulin-1 to nidogen depends on its C-terminal globular domain and a specific array of calcium-binding epidermal growth factor-like (EG) modules.

The calcium-binding basement membrane protein fibulin-1C was shown to bind nidogen in a calcium-dependent fashion. Fibulin-1C consists of small N (domain 1) and C-terminal (domain III) globular structures connected by a central rod (domain II) composed of nine epidermal growth factor (EG) modules, eight of which possess a consensus sequence for calcium binding. Several point and deletion mutants and chimeric protein constructs were used to define the nidogen binding epitope of fibulin-1C by surface plasmon resonance and solid phase assays. All recombinant products were obtained from transfected kidney cells in a folded form as shown by CD spectroscopy, electron microscopy and proteolysis. They were used to demonstrate that calcium-binding is essentially due to the EG modules possessing the consensus binding sequence. Deletion of domain III caused a 30-fold reduction in nidogen binding, whereas deletion of domain I had no effect, yet domain III alone was also inactive. Successive deletions of two to seven EG modules of domain II also caused partial of complete inactivation of binding depending on how many were deleted or their position relative to domain III. Site-directed mutagenesis within the calcium binding consensus sequences demonstrated a similar dependence. Replacement of seven of the calcium-binding modules by a similar tandem array from a related protein showed a distinct (fibulin-2) to almost complete loss of binding (fibrillin-1). This indicates a complex epitope structure involving domains II and III, which each may provide binding epitopes or stabilize each other.

Animals↗
PubMed1997

Dilemmas of anonymous predictive testing for Huntington disease: privacy vs. optimal care.

Some persons at risk for Huntington disease (HD) seek predictive testing under the protection of anonymity to reduce the risk of insurance discrimination for themselves and their families. While Canadian and European health care systems seem to limit insurance discrimination to life and disability insurance, U.S. residents do not have national health insurance and are concerned about health insurance discrimination. Two persons residing outside Canada requested predictive testing anonymously. Their primary reason for doing so was to avoid the risks of medical insurance discrimination. After a detailed preparatory session and agreement to counselling and to receipt of results in person, we agreed to provide anonymous testing to these persons. One participant, whose psychological assessment was unremarkable, coped well with the predictive testing process and did not have the CAG expansion. The other participant had considerable emotional problems prior to testing, which necesitated postponement of discussion of results and referral for psychiatric assessment and support. Both participants had difficulty maintaining anonymity. The provision of anonymous predictive testing raises several problems. With anonymous testing, clinicians cooperate with participants to exclude insurance companies from information. This may invalidate the contract with insurance companies. A policy response by insurance companies or a universal health care system to protect individuals is preferable. Individuals who request anonymous testing may be precisely those most vulnerable and in need of additional support and counselling. However, the preservation of anonymity is a burden to participants and may frustrate the clinicians' ability to establish rapport in counselling and to provide appropriate follow-up typically available through genetic counselling in predictive testing programs.

Adult↗
PubMed1997

Stimulation of RAR alpha activation function AF-1 through binding to the general transcription factor TFIIH and phosphorylation by CDK7.

The activity of the N-terminal activation function AF-1 of RAR alpha1 is abrogated upon mutation of a phosphorylatable serine residue (Ser-77). Recombinant RAR alpha was phosphorylated by a variety of proline-directed protein kinases in vitro. However, only the coexpression of cdk7 stimulated Ser-77 phosphorylation in vivo and enhanced transactivation by RAR alpha, but not by a S77A RAR mutant. Both free CAK (cdk7, cyclin H, MAT1) and the CAK-containing general transcription factor TFIIH phosphorylated Ser-77 in vitro. Furthermore RAR alpha bound free CAK and purified TFIIH in vitro, and RAR alpha-TFIIH complexes could be isolated from HeLa nuclear extracts. These findings represent the first example of activation of a transactivator through binding to and phosphorylation by a general transcription factor.

Amino Acid Sequence↗
PubMed1997

Opinions of dental consultants on the standard of referral letters in dentistry.

AIM: To ascertain the views of dental consultants on the relative importance of a range of topics relevant to specialist referral. SUBJECTS: 200 randomly selected dental consultants working in the UK in 1995. MAIN OUTCOME MEASURES: Data items which referral letters should contain; standard of referral letters; appropriate reasons for referral; how referrals could be improved; should restrictions be placed on specialist referrals. RESULTS: 161 replies were received. Overall there was only slight variation between specialities with regard to data items, appropriateness of referral and standard of referral letter. The perceived standard of referral letters was adequate or better on 76% of occasions; 21% were deemed to be of a poor standard; 2% were described as appalling. CONCLUSIONS: A Section 63 course on how to refer competently could be of benefit. Consultants were generally not in favour of restricting referrals to them.

Consultants↗
PubMed1997

Demonstration of discrete secreted and membrane-bound ocular mucins in the dog.

Our aims were to separate and characterize secreted canine ocular mucins, and to provide definitive evidence of membrane-bound mucins at the canine ocular surface. Mucus was collected by suction from the ocular surface of normal dogs and dispersed in guanidine hydrochloride and a cocktail of protease inhibitors. Caesium chloride density gradient centrifugation separated secreted mucins from membranes, which were collected from the top of the gradients. Membranes were extracted with octyl glucoside and screened using lectins and anti-mucin antibodies. Gradient fractions containing secreted mucins were constituted into pools on the basis of differential lectin and antibody staining. High molecular weight material from each pool was purified by gel filtration. This material, and the membrane extract, were reduced and alkylated. Vacuum blotting of separated materials after agarose gel electrophoresis was used to compare subunit structure. Density gradient profiles indicated three principal secreted glycoprotein peaks: one staining strongly with anti-mucin antibodies. Gel filtration demonstrated that each contained high molecular weight material. Vacuum blots demonstrated the presence of two secreted glycoproteins with differently sized subunits. On the basis of buoyant density, one of these may be lipid complexed. Membrane extracted material stained with anti-mucin antibodies, and vacuum blotting of this material provided evidence for two membrane-bound components. In conclusion, we have shown that normal canine ocular mucus contains two secreted mucins, each exhibiting different subunit structure; one of these mucins may undergo lipid complexation. Normal canine ocular mucus also contains two membrane-bound mucins: one of which is unique among membrane mucins in showing subunit structure.

Animals↗
PubMed1997

A study of problems associated with the delivery of enteral feed in critically ill patients in five ICUs in the UK.

OBJECTIVES: To describe the incidence of problems associated with enteral feeding in different patient groups and intensive care units (ICUs). To compare this incidence with specific feeding protocols and volumes of feed delivered. To identify for future study any interventions likely to improve delivery of enteral feed and to manage or eliminate problems. DESIGN: A prospective, descriptive study of problems associated with enteral feeding in five ICUs over a period of 9 months. SETTING: ICUs in two district general and three university hospitals. PATIENTS: ICU patients (age > 18 years) who received enteral feeding for a period > 24 h. MEASUREMENTS AND RESULTS: 193 patients were studied for a total of 1929 patient-days. On average, only 76% of the quantity of feed prescribed was delivered to the patient. The two main problems preventing delivery of feed were gut dysfunction and elective stoppage for procedures. ICUs with well-defined feeding protocols delivered significantly greater volumes of feed (p < 0.0001) than those without. Feeding was abandoned in 11% of patients, half of these due to gastric dysfunction. Only 2 of 193 patients were fed jejunally. CONCLUSIONS: The major factors associated with the interruption in delivery of feed are problems with gut function and stopping feed prior to a procedure. Use of specific feeding protocols is clearly associated with a greater volume of feed delivered and a greater percentage of the prescription delivered. These should be an integral part of all ICU protocols.

Adult↗
PubMed1997

Pelvic distraction to improve exposure in radical surgery for pelvic tumours in children.

We describe one patient who had pubic osteotomy and three who had symphysiotomy as an aid to radical tumour resections over the last 7 years. In each it was possible to distract the pelvis so improving access to the tumour. All four patients had pelvic rhabdomyosarcomata, three primarily in the prostate and lower bladder and one was a large tumour filling the pelvis, probably of bladder origin. No immediate or long-term complications of the procedure occurred, and in the two patients who died (2.5 years and 1 year post-surgery) or in the two survivors.

Child, Preschool↗
PubMed1997

Risk reversals in predictive testing for Huntington disease.

The first predictive testing for Huntington disease (HD) was based on analysis of linked polymorphic DNA markers to estimate the likelihood of inheriting the mutation for HD. Limits to accuracy included recombination between the DNA markers and the mutation, pedigree structure, and whether DNA samples were available from family members. With direct tests for the HD mutation, we have assessed the accuracy of results obtained by linkage approaches when requested to do so by the test individuals. For six such individuals, there was significant disparity between the tests. Three went from a decreased risk to an increased risk, while in another three the risk was decreased. Knowledge of the potential reasons for these changes in results and impact of these risk reversals on both patients and the counseling team can assist in the development of strategies for the prevention and, where necessary, management of a risk reversal in any predictive testing program.

Adult↗
PubMed1996

Adverse psychological events occurring in the first year after predictive testing for Huntington's disease. The Canadian Collaborative Study Predictive Testing.

A total of 135 participants in the Canadian predictive testing programme for HD were followed for at least one year in one of four study groups: increased risk (n = 37), decreased risk ( n = 58), uninformative (n = 17), or not tested (n = 23). Clinical criteria for an adverse event were a suicide attempt or formulation of a suicide attempt plan, psychiatric hospitalisation, depression lasting longer than two months, a marked increase in substance abuse, and the breakdown of important relationships. Quantitative criteria, as measured by changes on the General Severity Index of the Symptom Checklist 90-R and the Beck Depression Inventory, were also used to identify people who had adverse events. Twenty of the 135 participants (14.8%) had an adverse event. There were no significant differences between those with or without an adverse event with respect to age, sex, marital status, education, psychiatric history, general psychiatric distress, or social supports at baseline. However, evidence for depression was associated with an increased frequency of adverse events (p < 0.04). The adverse events were similar and seen with equivalent frequency in those receiving an increased risk or decreased risk and persons at risk who did not receive a modification of risk. However, a significant difference was found in the timing of adverse events for the increased and decreased risk groups (p < 0.0002). In the increased risk group all of the adverse events occurred within 10 days after results whereas, in the decreased risk group, all of the adverse events occurred six months or later after reviewing test results. These results suggest that people entering into predictive testing with some evidence of clinical depression warrant special vigilance and also suggest that counselling and support should be available for all participants in predictive testing irrespective of the direction of test results.

Adolescent↗
PubMed1995

Are we all of one mind? Clinicians' and patients' opinions regarding the development of a service protocol for predictive testing for Huntington disease. Canadian Collaborative Study for Predictive Testing for Huntington Disease.

There are currently different research programs in place to assess the effects of predictive testing for a few late-onset disorders, including Huntington disease (HD) and familial cancers. Prior to providing predictive testing as a service, we sought the views of both the patients and the clinicians as to the importance and value of different items in a research protocol for HD. We mailed questionnaires to 41 clinicians and 351 at-risk patients who had participated in the research protocol, to solicit their opinions on the relative importance of various components of the HD predictive testing research protocol. Completed questionnaires were received from 256 patients (73%) and 33 clinicians (80%). Most participants (96%) were satisfied with the program, and < 3% of persons receiving a modification of risk felt that predictive testing had impaired their quality of life. While there was consensus on the importance of most components of the protocol, significantly more clinicians than patients (97% vs. 72%; P = 0.02) felt it was essential to keep written material about HD as part of a service protocol. More patients than clinicians (83% vs. 27%) considered it essential to have 24-hr contact numbers following disclosure of test results (P < 0.0001). Patients also felt more strongly about the importance of counseling about technical aspects of predictive testing (84% vs. 77%; P < 0.02), and about having a support person attend counselling sessions with the patient (62% vs. 48%; P = 0.04). Nearly 25% of participants indicated that they would not want their general practitioner routinely involved in the predictive testing program. These findings have influenced the development of our service protocol, and they underscore the importance of involving both providers and consumers of predictive testing in the development of a service protocol for genetic testing.

Adolescent↗