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Biomedical subjects

J N Kearney

Publications and source records attributed to J N Kearney.

47 records · Page 3Linked to original sources
PubMed1990

The cutaneous microbiology of haired and hairless mice.

The cutaneous microflora of the mid-dorsal area of hairless and haired mice was studied by processing skin biopsies. In both C3H and CBA hairless genotype animals the prevalence of colonization and the bacterial density were significantly greater than in the haired animals. The dominant bacteria were staphylococci and aerobic coryneforms. No propionibacteria were isolated. Temporal studies with C3H mice showed that from 0 to 9 days after birth the cutaneous microflora reduced and from then on the haired genotype animals maintained a low cutaneous microflora, whilst hairless genotype animals gradually lost hair from head to tail and the microflora density increased. Reciprocal skin grafting between haired and hairless animals showed that the donor skin acquired the microflora characteristics of the recipient animal after 15 d post-grafting even though the donor skin remained morphologically true to genotype.

Animals↗
PubMed1989

Evaluation of ethylene oxide sterilization of tissue implants.

The ability of ethylene oxide (ETO) gas to penetrate tissue matrices was evaluated using Bacillus subtilis var niger (NCTC 10073) spore strips sandwiched between sheets of various tissues exposed to ETO for varying periods. The decimal reduction times (min) obtained using commercially prepared spores were: 7.97 for naked spores, 7.34 between amnion, and 6.39 between amnio-chorion, indicating complete penetration of the matrix by the gas. Similar conclusions were reached using skin and dura mater. The possible protective effect of serum was evaluated by drying spores suspended in serum in different ways, followed by exposure to the gas. Decimal reduction times obtained were: 8.67 (dried at 37 degrees C); 8.09 (dried at 55 degrees C) and 8.97 (freeze-dried) confirming slight protection. However, in all cases sterilization was achieved following 100 min ETO exposure, giving a 2.5 times safety factor for the commercial ethylene oxide sterilizer.

Bacillus subtilis↗
PubMed1989

Effects of antifungals on the viability of heart valve cusp derived fibroblasts.

Fibroblasts were isolated from fresh porcine aortic cusps and their identity confirmed morphologically and biochemically. The fibroblasts were used to assess the cytotoxicity of nystatin and amphotericin B at room temperature and 4 degrees C, following exposure periods of 4, 24, and 48 h. Except at the highest concentration and the longest exposure period at room temperature, nystatin had little detrimental effect compared with the nystatin free control. In contrast, amphotericin B proved highly cytotoxic. Published protocols for the use of amphotericin B in the disinfection of viable heart valve allografts would result in little residual fibroblast viability. We recommend that amphotericin B is no longer used in this situation.

Amphotericin B↗
PubMed1988

Antimicrobial properties of antiseptic-impregnated biological dressings.

Three antiseptics--chlorhexidine acetate, silver nitrate and povidone-iodine--were incorporated into biological dressings (human skin and amnio-chorion) and evaluated in vitro against disparate micro-organisms. Results indicated that antimicrobial levels of chlorhexidine and silver were released from the dressings over a clinically relevant time period, whereas povidone-iodine was ineffective. Chlorhexidine dressings demonstrated broad-spectrum activity, whereas silver dressings were most effective against Pseudomonas aeruginosa.

Anti-Infective Agents, Local↗
PubMed1984

The follicular distribution and abundance of resident bacteria on human skin.

A cryostat sectioning procedure was used to determine quantitative viable counts of microorganisms both on the surface and in successive layers of human cadaver skin biopsies. Also, using a previously described xenograft model, we investigated the dependence of microorganisms on the presence of sebaceous glands by using full thickness (1.5-2.0 mm) and split thickness (0.6 mm, ensuring sebaceous gland exclusion) human skin. Our results show substantial variation in the distribution and abundance of skin bacteria, even amongst biopsies from the same cadaver. In general, propionibacteria were distributed within a narrow band at varying depths beneath the skin surface whereas staphylococci were more broadly distributed. The importance of this with respect to topically applied antiseptics and antimicrobial agents is indicated. The xenograft studies demonstrated that propionibacteria were dependent on the presence of sebaceous glands whereas staphylococci were not.

Animals↗
PubMed1984

Correlations between human skin bacteria and skin lipids.

Correlation matrices were constructed for various human skin variables (propionibacteria, micrococcaceae, sebum excretion rate, percentage of free fatty acids and free fatty acid production rate). Two independent populations were studied (n = 87 and n = 103), and a subpopulation (n = 30) was investigated on three occasions at intervals of I month. In this way consistently high correlations could be differentiated from 'fortuitous' correlations. Propionibacteria versus micrococcaceae showed the highest correlation coefficient and propionibacteria versus percentage free fatty acids was also highly correlated. A scatter diagram indicated a relationship between the lower threshold of microbial density and sebum excretion rate. An explanation based on relative duct and gland size is presented.

Adolescent↗
PubMed1983

The vitamin requirements of Staphylococcus cohnii.

The vitamin requirements of 66 strains of Staphylococcus cohnii from various sources were determined using solidified and liquid chemically defined media. All the strains tested required nicotinic acid and thiamine. Biotin was either growth stimulatory or essential for 34 strains. Pantothenic acid was required by 21 of the 30 strains of known human origin but was not required by any of the 24 strains of murine origin. There was an association among Staph. cohnii strains to grow in the absence of pantothenic acid and biotin and the ability to produce acid from lactose and the possession of phosphatase activity (20 strains). The majority of strains requiring pantothenic acid and biotin were unable to ferment lactose and did not possess phosphatase activity (22 strains).

Biotin↗
PubMed1982

Maintenance of the normal flora of human skin grafts transplanted to mice.

Full-thickness human cadaver skin was maintained on the dorso-lateral thoracic region of hairless mice whose immune rejection mechanism was suppressed using anti-mouse-thymocyte globulin. The bacterial profile of the pregrafted skin did not differ significantly from the normal human microflora. In contrast, the murine skin exhibited quantitative and qualitative differences from the human flora, in particular by the complete absence of Propionibacterium acnes, the dominant bacterium on sebum-rich areas of human skin. The normal microbial profile of the human grafts was maintained throughout the experimental period despite the novel environmental milieu. There was little contamination of the grafts from the normal murine flora. It was concluded that the grafted human skin would provide a realistic model for studying the ecology of human cutaneous micro-organisms.

Animals↗
PubMed1980

A modified photometric technique for measuring sebum excretion rate.

Accurate measurement of sebum excretion is necessary to evaluate drugs such as anti-androgen and the new retinoic acid derivatives. Existing techniques are good, but some are inaccurate at high levels of sebum and are time-consuming for technicians. We have therefore, re-examined sebum excretion methodology and have developed a modified photometric technique. This technique, which utilizes a robust, portable machine gives data which are accurate at all levels of sebum production and reduces the technician time of analysis without loss of accuracy or reproducibility.

Humans↗