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Biomedical subjects

M J Simons

Publications and source records attributed to M J Simons.

At least 19 recordsLinked to original sources
PubMed1991

Chromosomal mapping of A1 and A2 adenosine receptors, VIP receptor, and a new subtype of serotonin receptor.

cDNA clones encoding four new receptors of the G-protein-coupled receptor family were obtained by selective amplification and cloning from thyroid cDNA and termed RDC1, RDC4, RDC7, and RDC8. RDC7 and RDC8 have recently been identified as A1 and A2 adenosine receptors, respectively. These cDNAs were utilized for chromosomal in situ hybridization to establish the genomic location of the corresponding genes in man. The results indicate that human RDC1, RDC4, RDC7, and RDC8 are in regions 2q37, 1p34.3-1p36.3, 22q11.2-22q13.1, and 11q11-11q13, respectively.

Chromosome Banding↗
PubMed1979

Histopathology of nasopharyngeal carcinoma: correlations with epidemiology, survival rates and other biological characteristics.

A total of 363 cases of nasopharyngeal carcinoma (NPC) in Singapore were classified into squamous cell carcinoma (SCC; 73 cases), non-keratinizing carcinoma (NKC; 178 cases) and undifferentiated carcinoma (UC; 172 cases). Possible biological differences between these histologic types and between tumors with and without lymphocytic infiltration were investigated by correlations with survival rates and with selected epidemiologic, immunovirologic, and immunogenetic data on the disease. The 5-year survival rates following radiotherapy were 25.3% for all cases and 58.8% for tumors restricted to the nasopharynx. The 5-year survival rate for SCC was poorer than for the combined NKC and UC groups (p less than 0.05). The 3-year survival rate was better for tumors with lymphocytic infiltration (p less than 0.05), but there were no differences in the 5-year survivals. The survival rates were better in females (p less than 0.01) and in the younger age groups (p less than 0.01). There were no significant correlations between histopathology of NPC and the distributions of cases by age, sex, HLA antigen profiles, or cell-mediated immune status. Squamous cell carcinoma was associated with lower levels of antibodies to the Epstein-Barr nuclear antigen (p less than 0.05), but there were no differences with respect to antibodies against other EBV related antigens. These findings support the view that SCC, NKC, and UC of the nasopharynx, as defined in the WHO classification, are variants of a fairly homogeneous group of neoplasms in the Singapore population.

Adolescent↗
PubMed1979

Geographic tongue--a manifestation of atopy.

One hundred patients with geographic tongue have been studied for evidence of an association with atopy. There was a significantly high frequency of personal and/or family history of asthma, eczema and hay fever amongst the patients when compared to a control population. A raised total serum IgE( greater than or equal to 200 u/ml) was significantly more frequent in patients compared to a control population. These findings confirm the impression that in some patients geographic tongue is a sign of atopy.

Adolescent↗
PubMed1978

Nasopharyngeal carcinoma and histocompatibility antigens.

New data are presented concerning the relationship between NPC and HLA antigens among Chinese. When attention is confined to newly diagnosed cases, it can be shown that, apart from the increased risk associated with the joint occurrence of A2 and B-Sin 2, there is also an increased risk associated with BW17 and a decrease in risk associated with A11. Among long-term survivors, however, BW17 is appreciably decreased, whereas A2 in the absence of B-Sin 2 or BW17 is increased. Among Malays, a non-Chinese group, there is an excess among NPC patients of a locus A blank, a blank which is probably associated with the AW19 complex.

Carcinoma↗
PubMed1978

Genetic components in susceptibility to nasopharyngeal carcinoma.

A series of blood samples from more than 200 histologically confirmed Chinese patients with NPC in Singapore were typed for 25 genetically controlled red-cell enzyme and five serum protein systems. A comparable number of patients suspected of having NPC but histologically negative and a series of healthy unrelated Chinese were typed for the same systems. The gene frequencies of NPC patients and controls differed by 4% or more in four of the 11 systems that showed variation; a further system, G6PD deficiency, also showed a significant difference between the two series but was excluded because of possible unreliability of the results from patients. Smaller differences existed in several other systems, including chromosome 6 markers closely linked to HLA. An analysis of differences within dialect groups showed a consistent effect for PGD, but for red-cell acid phosphatase there was a reversal of the difference between patients and controls among the Cantonese. These results need a larger series to confirm their validity. A breakdown of patients into those 30 years of age or older and those under 30 slightly enhanced the differences in gene frequencies. A multivariate analysis, using genetic distance statistics, showed a significant difference between NPC patients and controls, which is evident also when they are compared in the separate dialect groups. The histologically negative patients occupied an intermediate position. The study indicates that etiological factors resulting in clinically and histologically confirmed NPC operate on a genetically distinct subpopulation of Chinese in Singapore.

Acid Phosphatase↗
PubMed1977

Total body irradiation with 8 MeV X-rays in generalized malignant disease.

The authors describe their experience with total body irradiation (TBI) with 8 MeV-x rays in the treatment of disseminated tumors. With a dose of 125 rad, given three times with 2-week intervals, some objective remissions (6/26) were obtained, especially in patients with lymphomas. For solid tumors only subjective improvement could be achieved. The side-effects were acceptable. The authors came to the conclusion that total body irradiation may be an alternative to chemotherapy for certain cases of generalized cancer.

Antineoplastic Agents↗
PubMed1977

Histocompatibility leukocyte antigen patterns and nasopharyngeal carcinoma.

Incidence patterns indicated the prominent role of genetic factors in this type of cancer. A histocompatibility leukocyte antigen (HLA) profile of A2 and B-locus antigen, Singapore 2 (Sin 2), was identified. An association between these genes and increased risk for nasopharyngeal carcinoma (NPC), was confirmed. The risk was restricted to the "co-occurrence" of A2, B-Sin 2, suggesting that the genotype predisposing to the development of NPC was the A, B-Sin 2 haplotype. Similar associations were found to exist in Malaysian and Hong Kong Chinese so the A2, B-Sin 2 phenotype is a feature common to Asian Chinese in at least three locations. Preliminary HLA studies of medium NPC incidence in Tunisians and Malays indicated that patients with NPC of both ethnic types have altered HLA antigen profiles. If the findings of a locus-B antigen deficit in Tunisians and the role of A9 with B-locus antigens in Malays can be confirmed and clarified, the histocompatibility genetic hypothesis of NPC predisposition would be substantially strengthened.

Asian People↗
PubMed1977

Immunogenetic aspects of nasopharyngeal carcinoma. V. Confirmation of a Chinese-related HLA profile (A2, Singapore 2) associated with an increased risk in Chinese for nasopharyngeal carcinoma.

Histocompatibility locus A typing of 43 Malaysian Chinese and 51 Hong Kong Chinese patients with nasopharyngeal carcinoma (NPC) confirmed the association between the occurrence of A2-Sin 2 and the increased risk for NPC that was previously demonstrated in Singapore Chinese. The results support the previous interpretation that the histocompatibility locus A genotype of importance in NPC predisposition is the A2-Sin 2 haplotype. The histocompatibility locus A-linked, genetically determined NPC risk is common to Asian Chinese from at least three geographic locations.

Asian People↗
PubMed1976

Impaired general cell-mediated immune functions in vivo and in vitro in patients with nasopharyngeal carcinoma.

General cell-mediated immune (CMI) functions in NPC patients were investigated by the in vivo Mantoux and in vitro lymphocyte response to PHA assays. Thirty-eight (50%) of 76 untreated NPC patients were hyporesponsive in the Mantoux assay compared to 27 (25%) of 110 control patients. Forty-three (65.2%) of 66 untreated NPC patients also showed lymphocyte hyporesponsiveness to PHA compared to 15 (15.5%) of 97 control patients. Combined deficiencies were observed in 35 (42.2%) of 83 NPC patients compared to only 2 (3.3%) of 61 control patients. No difference in the frequency of immunodeficiency was observed between "early" and "late" disease patients. CMI functions of treated "remission" NPC patients were found to be impaired to the same extent as those of untreated NPC patients.

Adult↗
PubMed1976

Immunogenetic aspects of nasopharyngeal carcinoma. IV. Increased risk in Chinese of nasopharyngeal carcinoma associated with a Chinese-related HLA profile (A2, Singapore 2).

The results of this study of 110 Singapore Chinese with nasopharyngeal carcinoma (NPC) and 91 controls confirmed the association between the occurrence of HLA antigen Singapore 2 (Sin2) and NPC in the Chinese population, and indicated that their increased risk for NPC was confined to the joint occurrence of Sin 2 and A2 antigens. These findings suggested that the genotype of importance in susceptibility to NPC is the A2-Sin 2 haplotype.

Asian People↗
PubMed1976

Blood group genetic studies in an urban Chinese population.

The distribution of the blood group systems ABO, Rhesus, MNSs and P was studied in all or some of 1,007 Singapore Chinese, ABO gene frequencies were found to be consistent with previous studies and did not vary significantly between dialects. An individual of phenotype A2B was detected although the population showed no other evidence for the A2 gene. The possible significance of this observation in terms of weak H alleles in the population is discussed. The frequencies of the MNSs genes are consistent with previous studies. Two subjects appeared to lack the NA component of the N antigen. The frequency of the R1 gene of the Rhesus system was lower than has been detected previously and may relate to dialect differences. No examples of the CW antigen were detected. The P blood group distribution appears to be subject to regional variation. It is concluded that classification of Chinese into dialect groups is a useful way of assessing genetic heterogeneity.

ABO Blood-Group System↗