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Biomedical subjects

R H Osborne

Publications and source records attributed to R H Osborne.

At least 19 recordsLinked to original sources
PubMed1992

Maternal smoking and tooth formation in the foetus. I. Tooth crown size in the deciduous dentition.

Altogether 2159 pregnancies among black and white Americans in the Collaborative Perinatal Study and dental casts from the children at the age of 5-12 years were studied to find out the effect of maternal smoking on deciduous tooth crown growth. Minor crown size reduction (2-3%) in some dimensions was found in children whose mothers had smoked during pregnancy. The possible change in dimensions seems to be influenced by sex, race and smoking habit. The critical time periods of the gestational development (16th to 19th) weeks would possibly appear from these data to be targeted by the detrimental effect of maternal smoking. It is concluded that deciduous tooth sizes seem to be greatly unaffected when compared to reduction in birthweight.

Black People↗
PubMed1992

Effects of FMRFamide-related peptides and morphine on the isolated foregut of the locust Schistocerca gregaria.

1. Morphine and YAGFMamide were the most effective potentiators of 5-hydroxytryptamine (5-HT)-induced relaxation of the isolated foregut. 2. Morphine had no effect on proctolin-induced tissue contraction which was inhibited by YGGFMamide and YFMRFamide. 3. The differing potency of FaRPs and morphine to potentiate 5-HT effects and reduce proctolin responses suggests that there are two separate FaRP receptor sub types. 4. This proposal is supported by the observation that, while naloxone (10(-5) M) is a relatively potent antagonist of FaRP induced inhibition of proctolin contraction, it has less effect on FaRP-induced potentiation of 5-HT-induced relaxation.

Amino Acid Sequence↗
PubMed1990

Tyramine antagonizes proctolin-induced contraction of the isolated foregut of the locust Schistocerca gregaria by an interaction with octopamine2 receptors.

1. Octopamine (OA) (10(-7)-10(-5) M) relaxed isolated foreguts. Tyramine mimicked the effects of OA but was 64x less potent. 2. Proctolin (10(-8) M to 10(-6) M) induced contraction of isolated foreguts was antagonised non competitively by tyramine. 3. Mianserin (10(-6) M) was a non competitive antagonist of relaxation caused by tyramine but was without effect on proctolin induced contraction. 4. Caffeine (1 microM and 2 microM) caused non competitive inhibition of proctolin-induced tissue contraction. 5. It is concluded that tyramine antagonises proctolin-induced contraction of the foregut by activating an adenylate cyclase-linked OA2 receptor.

Animals↗
PubMed1987

The production of inflammatory compounds by Propionibacterium acnes and other skin organisms.

Culture supernatants from four species of skin microorganisms (P. acnes, P. avidum, P. granulosum and S. epidermidis) were assayed for smooth muscle contracting substances which are indicative of inflammatory activity. At least three types of smooth muscle contracting substances were detected. These were: first, a substance active on a rat fundic strip preparation and antagonized by N,N-DMT. Activity was enhanced when cultures were grown in the presence of tryptophan. This substance was probably tryptamine. Second, a substance active on a guinea-pig ileum preparation and antagonized by mepyramine. Activity was enhanced when cultures were grown in the presence of histidine. This substance was probably histamine. Third, a substance active on a rat fundic strip preparation but not antagonized by N,N-DMT, mepyramine, atropine or indomethacin. Activity was enhanced when cultures were grown in the presence of glucose. This activity was probably due to acetate, propionate or other short-chain fatty-acid salts. Chromatographic analysis confirmed the presence of histamine, tryptamine and short-chain fatty acids in the culture supernatants. These substances if produced in vivo may cause or contribute to inflammation and pain directly without the prior mediation of the immune system. Cell extracts of Propionibacterium species were analysed by bioassay for the presence of prostaglandin-like compounds. These could not be detected in any of the eight strains of organisms tested.

Acne Vulgaris↗
PubMed1986

Histamine production by Propionibacterium acnes in batch and continuous culture.

Histamine production by Propionibacterium acnes was studied using batch and continuous culture. In batch culture, the culture pH and the production of histamine closely paralleled the pattern of growth, increasing as the growth increased. Continuous culture studies using a chemostat and varying culture pH showed that highest levels of growth of P. acnes occurred at pH 6.0 and that two clear 'peaks' of histamine production were apparent at pH 4.5 and at pH 7.5. The levels measured at pH 7.5 were approximately one third the maximum value measured at pH 4.5. When P. acnes was grown at different dilution rates at pH 5.7, the histamine and biomass production rates increased proportionately as the growth rates were increased, except at the lowest relative dilution rate employed (0.75 microrel) where the production rate of histamine was higher than the value predicted by a proportional relationship.

Culture Media↗
PubMed1985

Cytotoxic activity of Propionibacterium acnes and other skin organisms.

Culture supernatants from four species of skin micro-organisms were tested against VERO (monkey kidney cells) and skin fibroblasts for cytotoxic activity. Cytotoxic activity was produced by the three species of Propionibacterium tested (P. acnes, P. avidum and P. granulosum), and this activity was highest when cultures were grown in the presence of glucose. In contrast, Staphylococcus epidermidis was devoid of cytotoxic activity whether grown in the presence of glucose or not. The agent responsible for the cytotoxic activity was heat stable, of low molecular weight and removable from supernatants by ether extraction. These properties, coupled with the finding that the levels of cytotoxicity are directly proportional to the concentrations of propionate measured in samples, suggests that propionate is the agent responsible for the cytotoxicity of the culture supernatants. Pure propionate and the salts of other carboxylic acids (CI to C5) were tested at the same concentrations and showed different degrees of cytotoxicity depending on their chain length. Propionate may have an important role in the aetiology of the disease acne vulgaris.

Acne Vulgaris↗
PubMed1979

The effect of depolarizing potassium concentrations on the efflux of GABA from rat dorsal medulla in vivo and from slices and synaptosomes.

The efflux of [3H]GABA from the dorsal surface of adult rat medulla overlying the dorsal column nuclei (DCN) was found not be influenced by increasing the concentration of potassium in the superfusing solution to 40 mequiv. Similarly, raised potassium was found not to influence the efflux from slices of the dorsal region of the caudal medulla containing the dorsal column nuclei. This lack of effect of raised potassium is not thought to be due to lack of GABAergic terminals in this region because there is good pharmacological evidence for their presence and bacause both electrical stimulation and 100 microM veratridine increased the efflux of [3H]GABA from such slices. Also, 40 mequiv potassium was found to increase the efflux of both endogenous and [3H]GABA from crude synaptosome preparations of this region without influencing the efflux of [14C]sucrose or [3H]leucine. This release of [3H]GABA was calcium-dependent, and was similar whether produced by 20, 40 of 60 mequiv potassium and occurred whether eos or AOAA was used to inhibit GABA metabolism. Release from synaptosomes could also be induced with 100 microM veratridine. Raised potassium was additionally found to prevent the increased efflux from slices produced by electrical stimulation and to increase the efflux from slices prepared from the brains of rats 14 days old. It is suggested that the astrocytic swelling produced by raised potassium concentration restricts the diffusion of GABA away from depolarized terminals.

Aminooxyacetic Acid↗
PubMed1979

The effect of prenatal factors on crown dimensions.

As shown in 870 white participants in the National Collaborative Perinatal Project (NCPP), maternal health status during pregnancy and birth size are systematically related to mesiodistal and buccolingual crown dimensions of I1, I2, dc, dm1, dm2 and M1. Maternal diabetes, maternal hypothyroidism and large size at birth are associated with larger maxillary and mandibular teeth in white children. Conversely, deciduous and permanent crown diameters are diminished in maternal hypertension, and in low birthweight and small birth-length conditions. These findings suggest that maternal and fetal (or gestational) determinants of both deciduous and permanent tooth crown dimensions may account for as much as half of crown-size variability with major implications to population comparisons and historical odontometric differences and trends.

Birth Weight↗
PubMed1977

Uptake studies of taurine in vivo and its effects on the course of experimental focal epilepsy in rats.

The passage of orally administered taurine across the intestinal wall to the blood plasma and target sites of neuromuscular excitability has been studied. This has been correlated with the effect of repeated oral dosing on the manifestations of cobalt-induced epilepsy in the rat. The blood-brain barrier and the organ distribution of taurine uptake have important implications in testing its effect on hyperexcitability phenomena.

Animals↗
PubMed1975

Dystrophia myotonica in a 47, XXY male.

Classical clinical manifestations of dystrophia myotonica were apparently unaltered by aneuploidy in a 47, XXY male. His extremely eunuchoid habitus may represent a contribution by the point mutation to his Klinefelter's syndrome. Association of the two disorders may be due to factors other than chance. The danger of overlooking Klinefelter's syndrome in males with dystrophia myotonica can be avoided by cytologic studies.

Adult↗