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Biomedical subjects

A C Green

Publications and source records attributed to A C Green.

At least 55 records · Page 3Linked to original sources
PubMed1995

Novel pharmacological sensitivity of the presynaptic calcium channels controlling acetylcholine release in skate electric organ.

The presynaptic terminals of skate (Raja montagui) electric organ were tested for their sensitivity to calcium channel antagonists. Acetylcholine (ACh) release and the elevation of intraterminal Ca2+ concentrations triggered by K+ depolarisation were studied. ACh release was measured as 3H efflux from slices of organ prelabelled with [3H]choline. Depolarisation caused a marked, Ca(2+)-dependent increase in 3H efflux that was completely blocked by 100 microM Cd2+ and by 300 nM omega-conotoxin-MVIIC (MVIIC). Inhibition by MVIIC was concentration dependent (IC50 of approximately 20 nM) and reversible. No inhibition was seen with nifedipine (5 microM) or the two other peptide antagonists studied: omega-conotoxin-GVIA (GVIA) at 5 microM and omega-agatoxin-IVA (Aga-IVA) at 1 microM. In a "nerve plate" preparation (a presynaptic plexus of nerve fibres, Schwann cells, and nerve terminals) changes in intraterminal Ca2+ concentrations were measured by microfluorimetry using fluo-3. An increase in fluorescence, indicating a rise in the free [Ca2+], rapidly followed K+ depolarisation, and this change was restricted to the nerve terminals. This response was insensitive to nifedipine (5 microM), GVIA (5 microM), and Aga-IVA (300 nM) but almost completely abolished by MVIIC (1 microM). MVIIC inhibition was concentration dependent and partially reversible. These results show that the nerve terminals in skate electric organ have calcium channels with a pharmacological sensitivity that is markedly different from the established L, N, and P types in other systems but shares some, but not all, of the features of the recently described Q type.

Acetylcholine↗
PubMed1995

Comparison of scores on WISC-III and WISC--R of urban learning disabled students.

Wechsler Intelligence Scale for Children-III IQs and Wechsler Intelligence Scale for Children--Revised IQs of 16 preadolescents who were learning disabled, urban students (14 black) receiving special education services were compared. Analyses indicated lower mean WISC-III IQs, correlations of .57, .74, and .72 between scores on Full, Verbal, and Performance Scales, respectively, and significant correlations of .44 to .80 between respective sets of subtests. Exceptions were Information (.34), Similarities (.30), and Picture Arrangement (.15). These results suggest that the WISC-III may compare favorably with the WISC--R, if replicated with a substantial group.

Black or African American↗
PubMed1995

The Nambour study of ocular disease. I. Design, study population and methodology.

In association with a study of actinic skin disease, we undertook a comprehensive survey of ocular disease in a population sample of the town of Nambour, Queensland, Australia. Particular emphasis was placed on those diseases with a putative relationship to exposure to solar radiation. In addition to collecting prevalence data, a randomized controlled trial was commenced to determine, among other things, if daily ingestion of 30 mg of beta-carotene supplements reduces the incidence or progression of ocular diseases possibly related to solar radiation exposure. The study design, population and methodology of the study are described in detail as a background to the future reporting of the results. The study should provide unique epidemiological information about eye disease in an Australian community setting due to the representative nature of the subjects and the comprehensive examination performed.

Adult↗
PubMed1994

Risk factors in the development of ocular surface epithelial dysplasia.

BACKGROUND: Ocular surface epithelial dysplasia involves a spectrum of diseases ranging from only minor eye irritation to blindness and potentially death. METHODS: A case-control study involving 60 patients with ocular surface epithelial dysplasia treated between 1972 and 1991 and 60 age- and sex-matched individuals was conducted to compare relative ultraviolet light exposures over their lifetimes. A standardized self-administered ultraviolet exposure questionnaire was used for assessment. RESULTS: Risk factors identified include phenotypic features such as fair skin (odds ratio [OR], 5.4; 95% confidence interval [CI], 1.1, 25.6), pale iris (OR, 1.8; 95%; CI, 0.9, 3.8), and propensity to sunburn (OR, 3.8; 95% CI, 0.7, 19.7), history of previous skin cancers removed (OR, 15; 95% CI, 2.0, 113.6), and being outdoors more than 50% of time in the first 6 years of life while living 30 degrees or less from the equator (OR, 7.5; 95% CI, 1.8, 30.6). CONCLUSION: These risk factors suggest that ocular surface epithelial dysplasia is an ultraviolet light-related disease.

Adult↗
PubMed1994

Epidemiology of solar keratoses.

Solar keratoses (SKs) or actinic keratoses are common dysplastic epidermal lesions which occur in pale-skinned individuals who are chronically exposed to intense sunlight. Together with basal cell carcinomas and squamous cell carcinomas, they constitute a major public health problem in such individuals. Reported SK prevalence rates range from 11 to 25% in various northern hemisphere populations, and amongst Australian adults the range is from 40 to 60%. In the only study to date reporting SK incidence data, 60% of subjects aged 40 years and over with SKs at baseline developed new lesions during 12 months of follow-up, compared with only 19% of those who were lesion-free on the first examination. Because existing epidemiological data on SKs are sparse, very little is known of their natural history, their role in carcinogenesis, or their preventability. In this review, current knowledge about the aetiology, diagnosis, and occurrence of SKs is discussed, as is the need for prospective studies in unselected communities. With accurate baseline data, public health authorities should be in a better position to determine the best preventive strategies, and to evaluate the effectiveness of these programmes.

Adolescent↗
PubMed1994

A survey of sunscreen use and sun-protection practices in Darwin.

A study was conducted to determine the prevalence and determinants of sun-protection practices in a sample of the non-Aboriginal population at the outdoor weekend markets in subequatorial Darwin, Northern Territory, at a time of intense sun exposure, between 11 a.m. and 1 p.m. from August to October 1992. All non-Aboriginal market-attenders who were seated within defined areas adjacent to food stalls were eligible to participate. Of 106 eligible market attenders, 105 (99 per cent) agreed to participate. Overall, fewer than 20 per cent of persons in this setting of extreme sun exposure were wearing sunscreen and less than one-third were wearing a hat. Only 44 per cent of people with a past history of skin cancer sitting in the midday sun had applied sunscreen and 61 per cent were wearing a hat; however, this was significantly more than those not reporting skin cancer (P < 0.002). The longer people had lived in the Northern Territory (compared with visitors and short-term residents) the less likely they were to have applied sunscreen in preparation for the midday sun (trend chi 2 = 3.99, P = 0.046). No association was demonstrated between the use of sunscreen and age or sex of the respondent. These results suggest that the sun-protection practices of visitors to the Northern Territory are less than optimal, and that among the longer-term residents of the Northern Territory who are at greatest risk of developing skin cancer, precautions against sun exposure could be greatly improved.

Adolescent↗
PubMed1992

Increasing incidence of cutaneous melanoma in Queensland, Australia.

BACKGROUND: Queensland, Australia, had the world's highest incidence rates of invasive cutaneous melanoma in the 1970s. PURPOSE: The purpose of this study was to monitor trends in melanoma incidence in Queensland. METHODS: We studied two time periods in which ascertainment was comparable. RESULTS: In the 7.5 years up to 1987, the incidence of invasive melanoma in Queensland increased by more than one half in women (to 42.89 per 100,000) and more than doubled in men (to 55.81 per 100,000), with the most dramatic increase seen in men over age 50 years. This higher increase in men is a reversal of the previously higher rates in women. In Queensland, cumulative risks of total cutaneous melanoma (in persons aged 0-74 years), including preinvasive melanoma, have increased to one in 14 in men and to one in 17 in women. There were large increases in age-standardized incidence rates of thin lesions (less than 0.75 mm) in both sexes but not of in situ lesions, and there were also increases in thicker lesions, especially on the backs of males. CONCLUSIONS: Although increased awareness and earlier diagnosis appear to have accompanied increased incidence, increased exposure to solar UV radiation during the past 50 years appears to be the most likely explanation for the rise in incidence rates. IMPLICATIONS: A better understanding is needed of the causes of melanoma and of the complex relationships between constitutional factors, ambient UV radiation, and sun-exposure behavior.

Adolescent↗
PubMed1992

Muscarinic autoreceptors of Torpedo electric organ are of the M1 subtype: evidence by radioligand binding using selective antagonists.

The presynaptic muscarinic autoreceptor of Torpedo marmorata electric organ has been characterised by radioligand binding studies using the subtype-selective antagonists pirenzepine, (+)-telenzepine, methoctramine, and AF-DX 116. The presynaptic receptor had relatively high affinity for the M1 antagonists pirenzepine and (+)-telenzepine (Ki = 35 and 7 nM, respectively) and lower affinities for the M2 antagonists AF-DX 116 and methoctramine (Ki = 311 and 277 nM, respectively). Comparison of these binding data with those from an M2 receptor (rat heart membranes) assayed under identical conditions and with data in the recent literature suggests that the Torpedo muscarinic autoreceptor has a pharmacology most similar to the M1 pharmacological subtype of muscarinic acetylcholine receptor.

Animals↗
PubMed1992

Cleft lip with or without cleft palate: associations with transforming growth factor alpha and retinoic acid receptor loci.

The first association study of cleft lip with or without cleft palate (CL/P), with candidate genes, found an association with the transforming growth-factor alpha (TGFA) locus. This finding has since been replicated, in whole or in part, in three independent studies. Here we extend our original analysis of the TGFA TaqI RFLP to two other TGFA RFLPs and seven other RFLPs at five candidate genes in 117 nonsyndromic cases of CL/P and 113 controls. The other candidate genes were the retinoic acid receptor (RARA), the bcl-2 oncogene, and the homeobox genes 2F, 2G, and EN2. Significant associations with the TGFA TaqI and BamHI RFLPs were confirmed, although associations of clefting with previously reported haplotypes did not reach significance. Of particular interest, in view of the known teratogenic role of retinoic acid, was a significant association with the RARA PstI RFLP (P = .016; not corrected for multiple testing). The effect on risk of the A2 allele appears to be additive, and although the A2A2 homozygote only has an odds ratio of about 2 and recurrence risk to first-degree relatives (lambda 1) of 1.06, because it is so common it may account for as much as a third of the attributable risk of clefting. There is no evidence of interaction between the TGFA and RARA polymorphisms on risk, and jointly they appear to account for almost half the attributable risk of clefting.

Blotting, Southern↗
PubMed1991

Premature ageing of the skin in a Queensland population.

OBJECTIVE: To determine the prevalence of premature ageing of the skin and to assess its associations with skin cancer and related risk factors in a Queensland population. DESIGN: Community-based prevalence survey of skin cancer and actinic skin damage. SETTING: Population of Nambour, Queensland, in December 1986. SUBJECTS: Random sample of 1539 residents aged 20 to 55 years for whom skin texture measurements were obtained, and a subsample of 807 whose skin reflectance was measured. MAIN OUTCOME MEASURES: Associations of premature ageing of exposed skin, assessed by silicone moulds of the dorsal skin of the hand, with present or past skin cancer, skin colour measured by reflectance and other related risk factors. RESULTS: Skin texture changes consistent with moderate to severe ageing were observed in 72% of men and 47% of women under 30 years of age. Severity of skin ageing was significantly associated with increasing age, and independently, with the presence of solar keratoses (P less than 0.01) and skin cancer (P less than 0.05). Increased deterioration was also correlated with decreasing reflectance (darker colour) of sun-exposed skin in both men (P less than 0.01) and women (P less than 0.05), but not with reflectance from sun-protected skin, that is inherent skin colour. Photoageing among men was associated with outdoor occupations, outdoor leisure activities, a tendency to sunburn and previous skin cancer. CONCLUSIONS: Marked premature ageing of exposed skin is common in residents of Queensland and is evident among adults in their twenties. Public education programs about the ill-effects of excessive sun exposure should emphasise not only the risk of skin cancer, but also the high risk of premature skin ageing.

Adult↗
PubMed1985

Cutaneous malignant melanoma in association with other skin cancers.

A case-control study of 232 cases of cutaneous malignant melanoma and 232 matched controls was performed to assess the association of the disease with nonmelanotic skin tumors--basal cell carcinomas, squamous cell carcinomas, and solar keratoses. There was a fourfold increase in risk of melanoma of all types when actinic tumors were present on the face. The risk was not restricted to the lentigo malignant melanoma class as might be expected but was significantly raised for superficial spreading melanoma and nodular melanoma as well (relative risk, 2.8; 95% confidence interval, 1.1-7.2). This relationship with lesions known to be associated with high-dose solar UV irradiation was supported by quantitative evidence that heavy sun exposure was associated with an increased risk of malignant melanoma.

Adolescent↗