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Biomedical subjects

H K Gill

Publications and source records attributed to H K Gill.

At least 19 recordsLinked to original sources
PubMed1997

Primitive neuroectodermal tumor in a child with tuberous sclerosis.

The case of a 13-year-old boy with tuberous sclerosis and primitive neuroectodermal tumor of bone is presented. A pathogenetic association between these two entities is postulated, the unifying underlying mechanism being a maldevelopment of the neural crest, or neurocristopathy.

Adolescent↗
PubMed1997

Infection of a chronically implanted iliac artery stent.

Pseudoaneurysm formation and infection at the site of iliac artery stenting are uncommon complications that occur soon after stent placement. We describe a case in which an infected pseudoaneurysm developed 22 months following stent implantation. Stent infection, although rare, has potentially disastrous implications, as made evident by a review of the literature. Prophylactic antibiotic therapy at the time of stent placement is recommended.

Aneurysm, False↗
PubMed1995

Reference ranges for lymphocyte subsets in a defined Malaysian population.

The aim of this study was to establish the lymphocyte subset reference ranges in a defined Malaysian population as well as to determine inter-racial differences for these values. Normal blood obtained from 152 subjects (55.9% Malay, 26.3% Chinese and 17.7% Indian) was immunophenotyped. Results obtained (expressed as mean +/- SD %), absolute count (x 10(6) cells/mm3) were as follows: CD3:66.5 +/- 8.6%, 2,066; CD4:33.2 +/- 8.5%, 1,028; CD831.6 +/- 8.9%, 982; CD19:12.0 +/- 0%, 5,374, and CD56+CD16:20.9 +/- 9%, 1,638. There were no significant differences between the percent lymphocyte subsets of the three racial groups. However, the absolute number of CD4 cells and CD19 cells in Chinese was significantly lower (p < 0.05) compared to the Indian and the Indian and Malay groups respectively. Comparison of our results with other reports showed that the percentage of Natural Killer cells in this population is higher than that reported for Caucasian population.

Adolescent↗
PubMed1993

Technetium-99m-tetrofosmin as a new radiopharmaceutical for myocardial perfusion imaging.

A new cationic complex, [99mTc(tetrofosmin)2O2]+, where tetrofosmin is the ether functionalized diphosphine ligand 1,2-bis[bis(2-ethoxyethyl)phosphino]ethane, has been synthesized and evaluated for potential use in myocardial perfusion imaging. The structure of the complex has been determined by x-ray crystallography of the 99Tc analog. In comparison with previously reported 99mTc complexes of alkyl-phosphines, the tetrofosmin species shows substantially increased clearance from nontarget tissue, especially blood and liver. A freeze-dried kit formulation has been developed. The kit provides a product of high radiochemical purity up to 8 hr after reconstitution at room temperature.

Animals↗
PubMed1992

Immunoreactive prolactin, progesterone and luteinizing hormone in the seminal plasma of buffalo (Bubalus bubalis).

The presence of immunoreactive prolactin, luteinizing hormone (LH) and progesterone in buffalo seminal plasma is reported for the first time. Correlations were obtained between various semen attributes and the levels of the above immunoreactive hormones. Statistically significant (P < 0.01) negative correlations were found between the levels of immunoreactive prolactin in semen and sperm motility and viability. The coefficient of multiple linear correlation (R2) between the levels of immunoreactive progesterone, prolactin and LH in the seminal plasma and the various attributes of semen revealed that immunoreactive progesterone and prolactin showed stronger interactions than did LH. The biological significance of these immunoreactive hormones in semen is discussed.

Animals↗
PubMed1990

Mycobacterium leprae reactive T cell clones from lepromatous leprosy patients after prolonged dapsone chemotherapy.

The proliferative responses of peripheral blood mononuclear cells (PBMC) to Mycobacterium leprae and BCG were studied in two groups of leprosy patients: a group of 8 lepromatous patients who had been on treatment for more than 20 years (TLL) and a group of 8 untreated lepromatous leprosy patients (ULL). The mean response to M. leprae of the TLL group was 6195 cpm with 5 of the 8 patients responding positively. The mean response to M. leprae of the ULL group was 617 cpm, with only 1 patient showing a positive response. The corresponding proliferative responses to BCG were 19,908 cpm in the TLL group and 7908 in the ULL group. Thirteen M. leprae reactive clones were established from 2 TLL patients and 5 M. leprae reactive clones were established from 2 tuberculoid leprosy patients. Seven of these clones, 4 from the TLL patients and 3 from the tuberculoid (TT) patients could be studied further. Three of the TLL clones responded specifically to M. leprae, while one of the clones exhibited a broad cross-reactivity to other mycobacteria. All of these clones were of the CD4+CD8- phenotype. Our findings suggest that responsiveness to M. leprae can be detected in vitro in a proportion of LL patients who have undergone prolonged chemotherapy, and that this response involves M. leprae reactive CD8+CD8- T cells, of which some appear to be specific to M. leprae.

Antigens, Bacterial↗
PubMed1988

Gene isolation with human T lymphocyte probes. Isolation of a gene that expresses an epitope recognized by T cells specific for Mycobacterium bovis BCG and pathogenic mycobacteria.

We have used human CD4+ T lymphocyte clones as primary probes to identify and isolate lambda gt11 rDNA clones that express epitopes recognized by T cells. The method that we describe here permits a direct survey of T cell epitope coding sequences in genomic DNA or cDNA libraries. A lambda gt11 library of Mycobacterium leprae DNA was screened with M. leprae-reactive human T cell clones as probes, allowing the isolation of a M. leprae DNA clone encoding the unidentified Ag. This DNA clone differs in restriction maps from those previously identified by antibody probes and encodes an epitope that is unique to vaccine strains of Mycobacterium bovis bacillus Calmette-Guérin and pathogenic mycobacteria. This method is generally applicable and should expedite the study of Ag and epitopes important to the T cell response in infections and in autoimmune diseases.

Antigens, Bacterial↗
PubMed1988

Vaccination of human volunteers with heat-killed M. leprae: local responses in relation to the interpretation of the lepromin reaction.

The early (Fernandez) and late (Mitsuda) lepromin reactions were closely examined in a group of healthy, BCG-vaccinated individuals who were given four doses of a heat-killed, armadillo-derived vaccine, i.e., 1.5 X 10(7), 5 X 10(7), 1.5 X 10(8), and 5 X 10(8) bacilli. There was a clear dose-response relationship for both the early and late reactions with no leveling of the responses within the range of doses examined. While the early response was negative in most of the volunteers, the late response was positive in all of the volunteers. No association was found between the early lepromin test and the pre-vaccination skin test to PPD. There was also no association between the early lepromin test and the pre-vaccination skin test response to a soluble Mycobacterium leprae antigenic preparation (MLSA) in general, but there was a good correlation between these two parameters at the highest vaccine dose. The late lepromin response showed no association with either the prevaccination or post-vaccination skin test response to PPD. However, there was a significant correlation between the late lepromin response and the post-vaccination skin test response to MLSA. In general, no association could be found between the in vivo skin tests and the in vitro lymphocyte transformation test (LTT). Thus, the lepromin test is essentially a vaccination which elicits a specific response to M. leprae antigens provided that the dose of armadillo lepromin given is higher than 5 X 10(7). Therefore, it is unsuitable as a diagnostic test for leprosy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

In vitro proliferation of lymphocytes from human volunteers vaccinated with armadillo-derived, killed M. leprae.

A killed, armadillo-derived Mycobacterium leprae vaccine was examined for its ability to induce cell-mediated responsiveness in purified protein derivative (PPD)-positive volunteers residing in a nonendemic country using the lymphocyte transformation test (LTT). A marked increase in the proliferative responses to a M. leprae-soluble antigen preparation was observed in the two groups which were vaccinated with the highest doses of the vaccine, i.e., 1.5 X 10(8) and 5 X 10(8) bacilli. This increase was observed in both groups 3 months after vaccination, and persisted for the study period of 1 year. The in vitro proliferative responses to whole bacilli, of both armadillo and human origin, showed a similar but smaller increase 3 months after vaccination. Some enhancement of responses to cross-reactive antigens, such as PPD, and to unrelated antigens such as streptokinase-streptodornase, tetanus toxoid and diphtheria toxoid, was also observed. Thus, the LTT revealed that while the killed M. leprae vaccine induced a specific cell-mediated response to M. leprae, it was also responsible for a nonspecific immune-enhancement effect in healthy volunteers.

Adult↗
PubMed1986

Induction of delayed-type hypersensitivity in human volunteers immunized with a candidate leprosy vaccine consisting of killed Mycobacterium leprae.

A killed armadillo-derived Mycobacterium leprae vaccine was examined for its ability to induce a delayed-type hypersensitivity (DTH) response in purified protein derivative (PPD)-positive human volunteers living in a leprosy non-endemic country. Four groups of individuals aged between 23 and 28 years were given 1.5 x 10(7), 5 x 10(7), 1.5 x 10(8) and 5 x 10(8)M. leprae intradermally. A marked increase in reactivity to the M. leprae-derived skin test antigen (MLSA) was observed in the vaccinated groups receiving the three highest doses of vaccine while there was very little change observed in their PPD reactivity. No unacceptable side-effects attributable to the vaccine were observed. The killed armadillo-derived M. leprae vaccine thus appears to be able to induce a DTH response in man at doses which do not cause unacceptable side-effects.

Adult↗
PubMed1984

Effect of irradiation on the precursor, activated and memory suppressor T cells for delayed-type hypersensitivity to sheep erythrocytes in mice.

The relative radiosensitivities of precursor (Tsp), activated (Ts) and memory (Tsm) suppressor T cells for delayed-type hypersensitivity (DTH) to sheep red blood cells (SRBC) were investigated in mice. Spleen cells from CBA mice, primed i.v. with 10(9) SRBC 3-4 days previously, contain specific Ts cells which substantially impair the induction of DTH to SRBC in normal syngeneic recipients. Exposure of mice to 400 rad irradiation 1 day before the priming completely eliminated the subsequent development of Ts cells. In contrast, 3 days after the priming injection, Ts cell activity in mice is resistant to doses higher than 600 rads. Mice primed 40 days previously with 10(9) SRBC contain Ts-cell memory which can be readily recalled by i.p. injection of 10(8) SRBC. The secondary Ts cells which specifically inhibit DTH induction can be demonstrated adoptively in normal recipients. Mice were exposed to various doses of irradiation 40 days after the priming and 1 day before the i.p. injection. Ts memory was significantly reduced by 300 rads and was completely abrogated by 400 rads. The relative radiosensitivities of the three subsets of suppressor T cells are in the order of Tsm = Tsp greater than Ts.

Animals↗
PubMed1983

Susceptibilities of algae and Legionella pneumophila to cooling tower biocides.

Nine algal strains and nine Legionella pneumophila strains were tested in laboratory culture for their susceptibility to inhibition by a variety of commercially available microbiocides. The responses ranged from ineffective to effective at 1/100 the manufacturers' recommended pulse doses. Tests were also performed to determine whether the action of the microbiocide was bacteriostatic or bacteriocidal.

Chlorophyta↗
PubMed1979

Regulation of delayed-type hypersensitivity IV. Antigen-specific suppressor cells for delayed-type hypersensitivity induced by lipopolysaccharide and sheep erythrocytes in mice.

Mice injected subcutaneously with 1 x 10(8) sheep red blood cells (SRBC) developed high levels of delayed-type hypersensitivity (DTH) to SRBC 4-8 days after injection. Such DTH was suppressed when 100 microgram lipopolysaccharide (LPS) was injected intravenously 1-2 days before or at the time of SRBC injection. This suppression of DTH was transferable by spleen, lymph node, thymus and bone marrow cells to sensitized or normal syngeneic recipients, but could not be transferred by serum. Suppressor cells were not induced by LPS alone or SRBC alone, and they were antigen-specific since DTH to chicken red blood cells was not affected. The suppressor cells appeared in the spleen in optimum number 3-4 days after induction. They were theta-negative and Ig-positive as judged by antiserum plus complement treatment and by Ig rosette separation. Attempts to obtain soluble suppressor factor from the suppressor cells by sonication or in vitro incubation were unsuccessful. Mitomycin C treatment of the suppressor cells completely abolished the suppressor activity. Thus, LPS, in conjunction with antigen, appears to induce a population of specific suppressor B cells which are capable of regulating T cell function.

Animals↗
PubMed1978

Regulation of delayed-type hypersensitivity. III. Effect of cyclophosphamide on the suppressor cells for delayed-type hypersensitivity to sheep erythrocytes in mice.

A previous study (Eur. J. Immunol. 1977. 7: 714) has shown that mice injected intravenously (i.v.) with 4 x10(9) sheep red blood cells (SRBC) produce cells which suppress delayed-type hypersensitivity (DTH). These suppressor cells are theta-positive, antigen-specific and act via a soluble factor which does not bear immunoglobulin determinants (Eur. J. Immunol. 1978. 8: 168). The present paper demonstrates that these suppressor cells are inhibitable by cyclophosphamide (CY). Mice injected with graded amounts of CY two days prior to SRBC injection, showed maximum augmentation of DTH at 200 mg/kg body weight, a dose which completely suppressed the appearance of splenic plaque-forming cells (PFC) to SRBC. In contrast, lower doses of CY enhanced both DTH and PFC responses. Time course studies showed that CY inhibited the precursors of suppressor cells and had little or no effect on suppressor cells which have already encountered antigens. This was further confirmed by passive transfer studies which showed tha- suppressor cells were inhibited if CY was administered at the same time or 2 days before SRBC injection, but were not affected if CY was given after antigen stimulation. Direct evidence for the effect of CY on suppressor cells was obtained by cell fractination with a Ficoll density gradient. The denser suppressor cell population was absent from the spleens of mice treated with 200 mg/kg of CY 2 days before i.v. injection with 1 x 10(9) SRBC.

Animals↗