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Biomedical subjects

T Samuel

Publications and source records attributed to T Samuel.

At least 19 recordsLinked to original sources
PubMed2004

The management of patients with morbid obesity in the anaesthetic assessment clinic.

One hundred and two patients with body mass indices of 37 kg x m(-2) or greater were interviewed in an outpatient assessment clinic over an 18-month period. All had been listed for elective surgery under general anaesthesia. All patients were given an explanation of the problems of morbid obesity in relation to anaesthesia. Three options were then offered to the patients: 1) to proceed with general anaesthesia as planned; 2) to undergo the planned procedure under some form of regional anaesthesia, or 3) to postpone surgery and attempt to lose significant amounts of weight. At this initial consultation, 24 patients chose option 1, 21 patients chose option 2, and 52 patients chose option 3. Four patients decided not to have the planned surgery. One patient decided to have his surgery performed at another hospital under general anaesthesia. Of the 52 patients who opted to lose weight, only eight succeeded in reducing their body mass index (BMI) by 3 or more during the period of the study. Of these eight, only four had reduced their BMI to below 35. In this study, an explanation of the problems of obesity in relation to anaesthesia, in advance of the date of surgery, had a significant effect on the type of anaesthesia chosen by most morbidly obese patients that were interviewed. Unfortunately, of those who decided to try and lose weight, only the occasional patient achieved significant weight loss. Although a laudable and advocated aim, optimization of patients with regard to their weight proved impractical in our study.

Adult↗
PubMed2004

Variations in the insecticide-resistance spectrum of Anopheles stephensi after selection with deltamethrin or a deltamethrin-piperonyl-butoxide combination.

When the larvae of Anopheles stephensi, a malaria vector, were selected with deltamethrin for 40 successive generations, there was a 60-fold increase in larval resistance to deltamethrin but no increase in the resistance of the adult mosquitoes. This result, and the observation that deltamethrin selection of adults for 40 generations resulted in only a six-fold increase in adult resistance to deltamethrin, indicated some stage specificity. When F(24) deltamethrin-resistant larvae were selected with 1:5 deltamethrin-piperonyl butoxide (deltamethrin-PBO), instead of deltamethrin alone, for 16 generations, the level of resistance to deltamethrin in the F(40) larvae was reduced by 6%-21%. Similarly, selection with deltamethrin-PBO of adults of the parental strain for 20 generations reduced the speed of the development of resistance to deltamethrin, compared with that seen using selection with deltamethrin alone. Deltamethrin selection appears to select initially a monooxygenase-based mechanism. When the monooxygenase-based mechanism is blocked, by treatment with PBO, selection of a kdr-type mechanism is accelerated, as is evident from increased cross-resistance to 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in the adults selected with deltamethrin-PBO. The implications of these results are discussed in terms of the management of the larval and adult stages of An. stephensi .

Animals↗
PubMed2001

The G2/M regulator 14-3-3sigma prevents apoptosis through sequestration of Bax.

In response to DNA damage and genotoxic stress, the p53 tumor suppressor triggers either cell cycle arrest or apoptosis. The G(2) arrest after damage is, in part, mediated by the p53 target, 14-3-3final sigma (final sigma). Colorectal tumor cells lacking final sigma are exquisitely sensitive to DNA damage. Here we analyzed the mechanism of this sensitivity in final sigma(-/-) as compared with final sigma(+/+) human colorectal tumor cells. Exposure to adriamycin resulted in rapid apoptosis only in final sigma(-/-) cells. This was further characterized by caspase-3 activation, p21(CIP1) cleavage, and CDK2 activation. Moreover, Bax was rapidly translocated out of the cytoplasm, and cytochrome c was released in final sigma(-/-) cells. Transient adenovirus-mediated reconstitution of final sigma in the final sigma(-/-) cells led to effective rescue of this phenotype and protected cells against apoptosis. The association of final sigma, Bax, and CDK1 in protein complexes may be the basis for this antiapoptotic mechanism. In conclusion, final sigma not only enforces the p53-dependent G(2) arrest but also delays the apoptotic signal transduction.

14-3-3 Proteins↗
PubMed2001

The 18 kDa antigen of Theileria equi is a specific but less abundant protein also expressed by parasites cultured in vitro.

A universally applicable test has not yet been developed for the reliable diagnosis of equine theileriosis, mainly because of the paucity of specific antigens and antigenic variation between different isolates. In this study, we used Theileria equi parasites cultured in vitro to identify potential diagnostic antigens. Using preparative isoelectric focusing to resolve the proteins in a lysate of infected erythrocytes, we identified an 18 kDa component of the parasite as a specific but poorly expressed antigen. This antigen also appears to have conserved epitope(s) between the isolates from the New and the Old World, as positive sera from both European and South American horses recognize it. The recombinant replica of this antigen might be a valuable tool for inclusion in the development strategy for a diagnostic test.

Animals↗
PubMed2000

Identification of CIP-1-associated regulator of cyclin B (CARB), a novel p21-binding protein acting in the G2 phase of the cell cycle.

The cyclin-dependent kinase inhibitor p21(cip1) regulates cell cycle progression, DNA replication, and DNA repair by binding to specific cellular proteins through distinct amino- and carboxyl-terminal protein binding motifs. We have identified a novel human gene, CARB (CIP-1-associated regulator of cyclin B), whose product interacts with the p21 carboxyl terminus. Immunocytochemical analysis demonstrates that the CARB protein is perinuclear and predominantly associated with the centrosome and mitotic spindle poles. In addition, CARB is also able to associate with cyclin B1, a key regulator of mitosis. However, cyclin B1-CARB complex formation occurs preferentially in the absence of p21. Unexpectedly, overexpression of CARB is associated with a growth-inhibitory and ultimately lethal phenotype in p21(-/-) cells but not in p21(+/+) cells. These data identify a novel mechanism that may underlie the effects of p21 in the G(2)/M phases of the cell cycle.

Cloning, Molecular↗
PubMed1999

Purification of a 28 kDa Babesia (Theileria) equi antigen and a 29 kDa spurious erythrocyte antigen from in vitro culture through ion exchange chromatography.

An extract of in vitro cultivated Babesia equi was fractionated using a MonoQ anion exchange column. Separation of a 28 kDa B. equi antigen from a 29 kDa spurious erythrocyte antigen, both of which were intensely immunoreactive, was achieved by chromatography of the infected erythrocyte proteins. Using tricine-SDS-PAGE, the 28 kDa antigen of B. equi showed multiple band resolution, while the 29 kDa antigen was consistently resolved as a single band. The 29 kDa antigen was identified in both infected and non-infected erythrocyte extracts. Moreover, B. equi antiserum recognised this antigen in the non-infected erythrocyte extract, and conversely serum from horses not infected with babesia detected the antigen in infected erythrocyte extract. This 29 kDa antigen could represent a horse erythrocyte isoantigen. The purified 28 kDa antigen is specifically recognised by B. equi antisera and therefore could be useful for the production of the recombinant replica and to employ these in further test systems.

Animals↗
PubMed1995

The costs of cancer care in the United States: implications for action.

The total annual cost of cancer care in the United States (including direct and indirect costs) has been estimated at more than $96 billion. Although third-party payers have led the effort to reduce these costs, such high expenditures must concern society as a whole, since money spent on cancer care, whether through insurance premiums, taxes to support Medicare, or payouts from family savings, could be used for other purposes. In the future, attention may be shifted to more cost-effective strategies, including greater prevention efforts and development of better diagnostic tools to permit early detection. Improved diagnosis, however, presents an anomaly in that with earlier detection, survival is greater but the overall direct treatment costs are higher. This is why when making decisions about allocation of medical resources, the indirect costs of morbidity and mortality (which are reduced with early diagnosis) must be considered as well as the direct cost.

Health Care Costs↗
PubMed1991

Impact of repeated application on the binding and persistence of [14C]-DDT and [14C]-HCH in a tropical soil.

An Indian sandy loam soil was initially treated with 1 kg a.i. ha(-1) of either [(14)C]-p,p'-DDT or [(14)C]-gamma-HCH during winter. DDT concentration after 30 days declined to 75.3%, which included 2.1% soil-bound residues. After 150 days, DDT levels further decreased to 42.4% with a concomitant increase in bound residues amounting to 5.9%. Identical treatment with HCH caused the residue levels to be reduced to 67.4 and 23.6%, after 30 and 150 days, respectively. During this period, the soil-bound residues of HCH increased from 5.2 to 12.8%. Repeat application to pre-treated soils in summer and subsequent field exposure for 30 days reduced the concentration of DDT to 52.1% and that of HCH to 42.4% of the total concentration following the second treatment. In parallel control experiments, which received only a single treatment, DDT levels declined to 61.3%, while HCH slumped to 45.3%, indicating a slower dissipation rate than in the corresponding repeated treatments. In repeat experiments, the soil-bound residues of DDT and HCH showed only a 1.07 to 1.08-fold increase in 30 days, as compared to three to ten-times increase in the control experiments. The results amply demonstrate that pre-treatment of tropical soils with DDT or HCH enhances their rate of dissipation and significantly reduce the formation of their soil-bound residues.

Journal Article↗
PubMed1989

The effect of temperature and solar radiations on volatilisation, mineralisation and degradation of [14C]-DDT in soil.

The influence of temperature and solar radiations on the rapid dissipation of DDT from tropical soils was studied by quantifying volatilisation, mineralisation, binding and degradation of ((14)C)-p,p'-DDT in a sandy loam soil. The bulk of the DDT loss occurred by volatilisation, which increased fivefold when the temperature changed from 15 to 45 degrees C. Degradation of DDT to DDE was also faster at higher temperatures. Mineralisation of DDT, though minimal, increased with temperature and time. Higher temperatures also enhanced binding of DDT to soil. Flooding the treated soil further increased volatilisation and degradation, although mineralisation was greatly reduced. Exposure of flooded and unflooded soils treated with DDT to sunlight in quartz, glass and dark tubes for 42 days during summer resulted in significant volatile losses. Volatilisation in the quartz tubes was nearly twice as great as that in the dark tubes The volatilised organics from the quartz tubes contained larger amounts of p,p'-DDE than the glass and dark tubes. Higher rates of volatilisation and degradation were found in flooded soils. Also significant quantities of p,p'-DDD were detected in addition to DDE. The data clearly show that volatilisation is the major mechanism for the rapid dissipation of DDT from Indian soils.

Journal Article↗
PubMed1987

Sperm-egg penetration of human spermatozoa treated with various rabbit antisera to human sperm antigens.

The effect of rabbit antisera to human whole spermatozoa, to human lactate dehydrogenase (LDH-X) and to human protamine 1 (HP1) and protamine 2 (HP2), was tested in the hamster zona-free egg penetration assay with human spermatozoa. The human spermatozoa were incubated with TEST yolk buffer washed and incubated with the antisera before penetration assay. Only antiserum to whole spermatozoa could inhibit the penetration capacity of treated human spermatozoa. The significance of the results as well as the advantage of the method used by us are discussed.

Animals↗
PubMed1980

Cross-reactions between protamines of different species: the role of arginine clusters.

Human and monkey sera containing autoantibodies to protamines reveal often strong cross-reactions with protamines of other species including salmon protamine. These cross-reactions can be readily detected both in the immunofluorescence test and th micro-complement fixation test. These sera react to a much lesser extent with poly-L-arginine. The results indicate that the cross-reactions of these protamines are not primarily due to clusters of arginine.

Animals↗
PubMed1980

The lessons of vasectomy-a review.

Vasectomy has become the most common method of permanent male sterilization for birth control. It is a simple operation that requires approximately 20 minutes to perform. Under local anaesthesia the vas deferens is cut and ligated. The patient is considered sterile when the ejaculate is sperm-free. Since spermatogenesis is not arrested by the operation and since the normal route of sperm removal is blocked, other mechanisms of sperm removal are developed. These mechanisms include sperm resorption into the interstitial tissue, granuloma formation, phagocytosis and immune response to sperm antigens. More than half of the men subjected to vasectomy develop demonstrable antibodies to one or more sperm antigens. Having been induced by the individual's own untreated antigen without the aid of external adjuvants, the response justifies the most rigorous definition of autoimmunity. The wide scale use of vasectomy, therefore, provides the clinical immunologist with a unique opportunity to study a longstanding, induced autoimmune response in otherwise normal human subjects. It is a matter of special importance to study these subjects carefully, in order to learn the maximum about human autoimmunity.

Autoantibodies↗
PubMed1979

Sperm autoantibodies as a consequence of vasectomy. II. Long-term follow-up studies.

Thirty-four out of fifty-two vasectomized men studied previously were studied again about 5 years after vasectomy for sperm-agglutinating and sperm-immoblizing antibodies, and for antibodies to human protamine. Only one man lost his already weak antibody activity, whilst one out of eight men, negative at 1 year, appeared to be positive at 5 years. Slightly higher titres in one of the three sperm antibody tests were found in the sera of about 30% of the men. Only in three (9%) was there a rise of two or more steps in more than one technique. Agglutinins and immobilizins were shown to be strongly correlated, as was the case with antibodies to human protamine and head-to-head agglutinins. Seminal plasma sperm agglutinins were detected in the samples of only four (out of thirty) men, in low titres. Circulating immune complexes tested with various techniques were only found in a few sera and not consistently. This prolonged study shows that sperm autoantibodies formed within 1 year after vasectomy are persistent. Their role in remaining infertility after reanastomosis requires further study.

Antigen-Antibody Complex↗