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Biomedical subjects

R W Armstrong

Publications and source records attributed to R W Armstrong.

At least 55 records · Page 3Linked to original sources
PubMed1985

Synthesis and antimicrobial evaluation of bicyclomycin analogues.

The synthesis and antimicrobial evaluation of novel bicyclomycin analogues are described. The series of analogues were prepared from the basic 8,10-diaza-2-oxabicyclo[4.2.2]decane-7,9-dione, 7,9-diaza-2-oxabicyclo[3.2.2]nonane-6,8-dione 8,10-diaza-5-methylene-2-oxabicyclo[4.2.2]decane-7,9-dione and 7,9-diaza-4-methylene-2-oxabicyclo[3.2.2]nonane-6,8-dione nuclei. For compounds where R1 = p-methoxybenzyl, deprotection of the lipophilic amides with ceric ammonium nitrate affords the corresponding lipophobic free amides. The basic bicyclic nucleus of bicyclomycin (8h, R1 = R2 = R3 = R4 = H) has been synthesized for the first time as well as increasingly more complex congeners bearing the C-6 OH, 5-methylene; C-1'-C-3' trihydroxyisobutyl group. In general, it has been found that the bicyclic nucleus of bicyclomycin is devoid of antimicrobial activity, the entire structure of bicyclomycin being generally obligate for activity. In one instance, the racemic analogue 10c (R1 = CH2Ph, R2 = OH, R3 = H) showed interesting antimicrobial activity against several Gram-positive organisms; the minimum inhibitory concentrations were of the same order of magnitude as bicyclomycin displays toward Gram-negative organisms. Totally synthetic (+/-)-bicyclomycin was half as active as the natural antibiotic. The design, synthesis, and antimicrobial activity (and/or lack thereof) of bicyclomycin and the analogues are discussed in the context of a proposed chemical mechanism of action.

Anti-Bacterial Agents↗
PubMed1985

Epidemiology of nasopharyngeal carcinoma in Malaysia and Hong Kong.

We conducted 2 case-control studies with Malaysian and Hong Kong Chinese and investigated the association between salted fish intake and nasopharyngeal carcinoma (NPC). Both studies show a highly significant association between salted fish intake, especially during childhood, and NPC. Furthermore, from our results we estimate that the majority of NPC cases occurring in the southern Chinese can be attributed to their consumption of this food early in life.

Adult↗
PubMed1983

Salted fish and nasopharyngeal carcinoma in Malaysia.

The evidence for a hypothesis that eating salted fish is associated with nasopharyngeal carcinoma (NPC) is reviewed. The hypothesis was tested among Malaysian Chinese using a matched case-control design. The kinds of salted fish and patterns of use were also investigated in a control group comprising 100 Chinese, 50 Malay and 50 Indian households. During 1980, in Selangor, Malaysia, interviews with 100 Chinese cases of NPC and 100 non-disease controls indicated that salted fish consumption during childhood was a significant risk (relative risk = 3.0, P = 0.04), with an elevated risk for daily as opposed to less frequent consumption. Salted fish consumption during adolescence was a less significant risk, and current consumption not at all. There were 19 kinds of fishes reported as being eaten as salted fish by the 200 control households. There were marked differences between ethnic groups in preference for different kinds: Chinese preferred red snapper (74% of households), Malay jewfish (54%) and Indian red snapper (28%). Salted fish was hardly ever eaten daily by any household; weekly was a moderate frequency in all ethnic groups; less than weekly most common. There were no statistically significant differences between Chinese NPC case and non-disease control participants in kind of salted fish eaten. Results were the same when the data were analyzed by sex, subethnic group and income.

Animals↗
PubMed1983

Salted fish and inhalants as risk factors for nasopharyngeal carcinoma in Malaysian Chinese.

We conducted a case-control study of nasopharyngeal carcinoma among Malaysian Chinese to test inhalants, salted fish consumption, and use of tobacco, alcohol, and nasal ointments as risk factors for the disease. Interviews with 100 cases and 100 controls indicated that salted fish consumption during childhood was a significant risk factor (relative risk, 3.0; p = 0.04); childhood daily consumption of this food item compared to nonconsumption carried a relative risk of 17.4 [95% confidence interval = (2.7, 111.1)]. Occupational exposure to smokes (relative risk, 6.0; p = 0.006) and to dusts (relative risk, 4.0; p less than 0.001) was also significantly associated with nasopharyngeal carcinoma. The two risk factors (consumption of salted fish and exposure to smoke and/or dust) were independent of each other. There was no association between nasopharyngeal carcinoma and tobacco, alcohol, or nasal ointments.

Administration, Intranasal↗
PubMed1982

Epidemiology and prospects for a cancer registry in Malaysia.

The history of efforts to establish a cancer registry in Malaysia since 1961 is reviewed. In 1980, the staff of the Institute for Medical Research in Kuala Lumpur was authorized to develop an official registry that would combine the resources of the various university faculties, the hospitals, research institutes, and the Cancer Society. Special registries operate for oral precancerous conditions and for nasopharyngeal carcinoma (NPC). The topics of recent epidemiological studies include: a review of all cancers diagnosed at the University Hospital during 1972-74, the association of Epstein-Barr virus and NPC, social and environmental factors associated with NPC, oral cancers, and childhood cancers.

Child↗
PubMed1981

Peripheral concentrations of gonadotropins and progestins during pregnancy in rabbits after active immunization against testosterone.

The effects of active immunization of female rabbits against testosterone on various endocrine parameters during pregnancy were examined. Peripheral blood samples were obtained from immunized rabbits at timed intervals after mating up to the 29th day of pregnancy, when the rabbits were killed and various tissues were analyzed. Progesterone concentrations were higher in testosterone-immunized rabbits (TIR) than in controls during pregnancy. Luteinizing hormone (LH) and follicle-stimulating hormone concentrations were not significantly different in controls and TIR during pregnancy. Both progestins and gonadotropins showed the expected coitus-induced increases, but LH levels were higher in TIR. The binding of testosterone in fetal plasma and amniotic fluid was higher in TIR than in controls. Weights of fetuses and litter size were not significantly different in TIR and controls. These data suggest that testosterone may play a role during pregnancy in the rabbit.

Amniotic Fluid↗
PubMed1979

Incidence of nasopharyngeal carcinoma in Malaysia, 1968--1977.

A record of all known cases of nasopharyngeal carcinoma in Malaysia is complete for 10 years from 1968 to 1977. Special efforts in case-finding were made in the State of Selangor where conditions are optimal. Age-adjusted incidence rates among Chinese males and females were 16.5 and 7.2 per 100,000, among Malay males and females 2.3 and 0.7 and among Indian males, 1.0. There were no significant changes in incidence rates over the 10-year period for sex and ethnic groups, or for Chinese subethnic groups. In Chinese subethnic groups, rates were highest among Cantonese, moderate among Khek and lowest among Hokkien and Teochiu. Standardized incidence ratios using Selangor as the standard population indicate considerable under-reporting in the less urban states of Malaysia, particularly among females. In Selangor, incidence rates were similar for urban and rural residents, but the frequency of cases was higher among Chinese working in industry and living in poor neighbourhoods.

Carcinoma↗
PubMed1979

Cancer incidence in Malaysia.

No population-based cancer registry exists in Malaysia; thus our main sources of incidence data were biopsy series. We determined the frequency of cancers by body site, sex, and ethnic group from biopsy records of the Division of Pathology of the Institute for Medical Research in Kuala Lumpur for the years 1969-71. We then made comparisons of leading sites with data from the Singapore Cancer Registry. Relative risk values for 21 sites indicated significant differences among ethnic groups for cancers of the nasopharynx, larynx, lung, bone, skin, cervix, ovary, prostate, and penis and for lymphomas.

Epidemiologic Methods↗
PubMed1978

Morphological changes in the rabbit ovary after active immunization to testosterone.

The role of testosterone in follicular development was investigated by immunizing female rabbits (mean wt 1.4 kg) to testosterone-3-bovine serum albumin (T-3-BSA). Controls received BSA. Follicular diameters and histology, and ovarian and uterine weights were recorded at intervals up to 11 weeks. At 5 weeks T-3-BSA ovaries did not differ from controls in either histology or follicular diameter (number of follicles greater than or equal to 1.0 mm were 12.5 +/- 3.4 and 17.0 +/- 1.0 for BSA and T-3-BSA treated animals respectively). By 8 weeks T-3-BSA animals had multiple cystic and hemorrhagic follicles. T-3-BSA ovaries contained more follicles greater than or equal to 1.0 less than 1.5 mm (27.3 +/- 3.1 vs. 15.3 +/- 2.9, p less than 0.01) and greater than or equal 1.5 mm diameter (5.8 +/- 1.7 vs. 0.4 +/- 0.3, p less than 0.005). At 11 weeks T-3-BSA ovaries contained more follicles less than 1.5 mm in diameter (5.0 +/- 0.9 vs. 0.9 +/- 0.3, p less than 0.001). Increased vascularization, some thecal hypertrophy and marked interstitial cell hypertrophy were characteristic of the T-3-BSA ovaries at 8 and 11 weeks. These results suggest that testosterone has a role in the regulation of follicular development.

Animals↗
PubMed1978

Effects of active immunization of female rabbits against testosterone.

Prepubertal (immature) and mature female rabbits were actively immunized against testosterone-3-oxime-bovine serum albumin over a period of 11 weeks. The antibody titre was significant in all animals by 5 weeks. The concentration of FSH in prepubertal animals decreased significantly (P less than 0.001) between weeks 1 and 5, but no significant changes were observed in the concentration of LH at any time. After immunization for 8 weeks, there was a significant (P less than 0.05) increase in the serum concentration of androgen and the percentage of bound testosterone also increased (P less than 0.05). The serum concentration of oestradiol increased after immunization for 11 weeks, compared with values at 8 weeks (P less than 0.05) and oestradiol binding also rose by week 5 (P less than 0.01). Libido was not affected and significantly (P less than 0.005) increased numbers of ovulations were noted in immunized animals. These results suggest that immunization of the female rabbit against testosterone may disrupt the normal regulation of follicular maturation.

Animals↗
PubMed1977

Nasopharyngeal carcinoma: opportunities for international collaborative research in Malaysia and Hawaii.

Malaysia and Hawaii have several advantages for epidemiologic and laboratory studies on nasopharyngeal carcinoma. Both have multiethnic populations with different incidence rates of nasopharyngeal carcinoma and different life-styles. Malaysia has large populations of Chinese, Malaya, and Indians, and the number of cases of nasopharyngeal carcinoma at any one time is comparatively large. Incidence rates for 1968--72, age-standardized to the World population, for Guangdong hua (Cantonese Chinese) in Malaysia were 24.3/100,000 for males and 12.0/100,000 for females. In Hawaii, the ratio was 12.9/100,000 for males and 6.7/100,000 for females. The small number of cases in Hawaii would require that research in that State be conducted in collaboration with research elsewhere with larger case numbers.

China↗
PubMed1974

Incidence of nasopharyngeal carcinoma in Malaysia, with special reference to the state of Selangor.

A "registry" of all known cases of nasopharyngeal carcinoma in Malaysia, 1968-72, was established. Attention was focused on the State of Selangor where conditions are best for case finding. Age-adjusted incidence rates among Chinese males and females were 17·3 and 7·3 per 100,000; among Malay males and females, the rates were 2·5 and 0·3 and among Indian males, 1·1. The detailed ethnicity of 192 cases in Selangor was established. Estimated incidence rates for the Chinese sub-groups agreed with the pattern observed elsewhere: highest among the Cantonese, lowest among the Hokkien/Teochiu, with the Khek in between. There was no correlation between histological type and sub-ethnic group among the Chinese cases.

Adolescent↗