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Biomedical subjects

J H Bennett

Publications and source records attributed to J H Bennett.

At least 37 records · Page 2Linked to original sources
PubMed1993

Odontogenic squamous cell carcinoma with osseous metaplasia.

Intra-osseous carcinomas of the jaw are rare tumours, thought to arise from residual elements of the odontogenic epithelium. We report an additional case which, unusually, was characterised by marked osseous metaplasia. We propose that the new bone formed around the tumour is the result of an epithelial-mesenchymal interaction between malignant odontogenic epithelium and osteogenic precursor cells in the surrounding stroma.

Carcinoma, Squamous Cell↗
PubMed1993

Drug samples.

Explore the source record for details and available documents.

Drug Industry↗
PubMed1993

Follow-up Papanicolaou smear for cervical atypia: are we missing significant disease? A HARNET Study.

BACKGROUND: The presence of cervical atypia on the Papanicolaou (Pap) smear may be an indicator of significant cervical disease. Many investigators recommend that colposcopy be performed in these women. We wished to determine the prevalence of undetected cervical intraepithelial neoplasia (CIN) among women identified as having cervical atypia by cytologic testing in a primary care setting. METHODS: Pap smears were performed on all women (N = 7458) attending six family practice offices for a health maintenance examination from August 1989 through February 1991. Cytologic specimens were obtained using an endocervical Cytobrush and wooden spatula. Consenting subjects with cervical atypia underwent repeat Pap smear testing immediately before a colposcopic examination after a 4- to 6-month waiting period. RESULTS: One hundred fifty-nine women identified as having cervical atypia consented to having a colposcopic examination. Of these, 96 (60%) demonstrated abnormalities on biopsy, including 40 with condyloma, 41 with CIN I, and 15 with CIN II to III. The false-negative rate of the follow-up Pap smear for detecting these cases of condyloma and CIN was 57%. CONCLUSIONS: One third of the women with cervical atypia identified on an initial Pap smear in this primary care community setting had CIN after colposcopic biopsy. The single follow-up Pap smear obtained with the endocervical Cytobrush and wooden spatula failed to detect one half of the cases of biopsy-proven CIN. Further studies regarding the use of additional screening methods for follow-up are necessary.

Adolescent↗
PubMed1992

Gonadotrophin-induced oestrus and ovulation in the polyovulatory marsupial Sminthopsis crassicaudata.

Sminthopsis crassicaudata is a small (approximately 16 g) polyovulatory dasyurid marsupial which has the potential to become an important model species. This study examined the use of exogenous hormone treatment to manipulate the breeding of S. crassicaudata and as a means to obtain timed developmental stages for further study. Two thirds (21/32) of the females treated with 1.0 or 5.0 I.U. of pregnant mare serum gonadotrophin (PMSG) had ovulated when the contents of their reproductive tracts were examined 5 or 6 days later. Only one of eight females treated with 0.2 I.U. PMSG had ovulated in the same period. Although a similar proportion of animals treated with 1.0 I.U. and 5.0 I.U. ovulated, the ovulation rate was significantly lower when the higher dose was administered (mean of 10.5 ovulations per female v. 3.8 ovulations per female). In addition, the ovaries of 6/8 of the animals treated with 5.0 I.U. PMSG had luteinized follicles with degenerating oocytes, evidence of over-stimulation. Follicular luteinization also occurred in 4/8 animals treated with 1 I.U. PMSG. Oocyte maturation and ovulation occurred following PMSG stimulation without injection of synthetic gonadotrophin releasing hormone (GnRH). Treatment with a 10-micrograms dose of GnRH following PMSG seemed to have no effect on the outcome. Of the females that had ovulated by Day 6, three quarters had mated and some had fertilized eggs and two-cell embryos in the oviducts and uteri. In a further series of experiments the subsequent development of embryos conceived after PMSG treatment was assessed. Two thirds of treated females mated within 7 days of treatment and 60% of these matings yielded embryos when examined 11 days after PMSG. However, full-term development was only achieved in one animal. Gonadotrophin treatment of S. crassicaudata thus may have application as a means to obtain mature or maturing oocytes, cleavage stage embryos and blastocysts, but at this stage it appears not to offer promise as a method to achieve full-term development.

Animal Husbandry↗
PubMed1992

Evidence for an inverse relationship between the differentiation of adipocytic and osteogenic cells in rat marrow stromal cell cultures.

The differentiation of adipocytic and osteogenic cells has been investigated in cultures of adult rat marrow stromal cells. Adipocytic differentiation was assessed using morphological criteria, changes in expression of procollagen mRNAs, consistent with a switch from the synthesis of predominantly fibrillar (types I and III) to basement membrane (type IV) collagen, and the induction of expression of aP2, a specific marker for differentiation of adipocytes. Osteogenic differentiation was assessed on the basis of changes in the abundance of the mRNAs for the bone/liver/kidney isozyme of alkaline phosphatase and the induction of mRNAs for bone sialoprotein and osteocalcin. In the presence of foetal calf serum and dexamethasone (10(-8) M) there was always differentiation of both adipocytic and osteogenic cells. When the steroid was present throughout primary and secondary culture the differentiation of osteogenic cells predominated. Conversely, when dexamethasone was present in secondary culture only, the differentiation of adipocytes predominated. When marrow stromal cells were cultured in the presence of dexamethasone in primary culture and dexamethasone and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3; 10(-8) M) in secondary culture, the differentiation of adipocytes was inhibited whereas the differentiation of osteogenic cells was enhanced, as assessed by an increase in expression of osteocalcin mRNA. The results, therefore, demonstrate an inverse relationship between the differentiation of adipocytic and osteogenic cells in this culture system and are consistent with the possibility that the regulation of adipogenesis and osteogenesis can occur at the level of a common precursor in vivo.

Adipose Tissue↗
PubMed1992

Monoclonal antibody BRL 12 reacts with bone keratan sulphate proteoglycan.

Our previous studies suggest that a monoclonal antibody, BRL 12, reacts with a specific product of differentiated cells of the osteoblastic lineage. In the present study, the bone constituent recognized by this antibody has been characterized by gel filtration, ion exchange chromatography, protein blotting and immunolocalization. Our findings show that the antibody reacts with an epitope associated with the core protein of rabbit keratan sulfate proteoglycan (KSPG), a molecule which shares considerable homology with the sialoprotein present in the bone tissue of other mammalian species.

Animals↗
PubMed1992

Are Papanicolaou smears enough? Acetic acid washes of the cervix as adjunctive therapy: a HARNET study. Harrisburg Area Research Network.

BACKGROUND: The Papanicolaou smear has a false-negative rate ranging from 10% to 50%. Adjunctive screening methods for detecting cervical disease are thus of interest. We studied an adjunctive acetic acid wash of the cervix to detect additional cases of cervical disease not found by the Papanicolaou smear. METHODS: All women attending six family practice offices for health maintenance during the period August 1989 through April 1990 were examined (N = 2827). Papanicolaou smears were obtained using a Cytobrush and wooden spatula. Each subject's cervix was also visually examined 1 minute after application of 5% acetic acid. Women with abnormal Papanicolaou smear results or abnormal acetowhite areas on visual inspection of the cervix underwent colposcopy. RESULTS: Ninety-three cases of biopsy-proven condyloma or cervical intraepithelial neoplasia (CIN) were found on the basis of abnormal Papanicolaou smear results alone, 33 on the basis of abnormal acetic acid wash results alone, and 14 on the basis of abnormal results from both a Papanicolaou smear and an acetic acid wash. The prevalence of CIN was 3%. The overall positive predictive value for abnormal results obtained by acetic acid wash was .55 (95% CI = .43 to .63). CONCLUSIONS: Using a 1-minute 5% acetic acid wash improves the detection of cervical disease by 30%. Consideration should be given to augmenting the Papanicolaou smear with this safe, simple, and effective technique on premenopausal women during regular health maintenance examinations.

Acetates↗
PubMed1991

Adipocytic cells cultured from marrow have osteogenic potential.

Stromal colonies with fibroblastic morphology grown from rabbit marrow cells in culture supplemented with foetal calf serum. In this study the same marrow cells cultured with autologous rabbit plasma and hydrocortisone form colonies of a single lineage that express the adipocytic phenotype. A comparison of the potential for differentiation of cloned cell populations grown from fibroblastic and adipocytic colonies has been made using an in vivo diffusion chamber assay. The adipocytic colonies differentiated and grew to a limited size in medium with rabbit plasma and hydrocortisone, but attempts to isolate them and expand them in this medium failed. When the serum supplement was changed to foetal calf serum at day 10 the cells in the adipocytic colonies acquired a less differentiated morphology, there was a large increase in colony growth and cells were produced in sufficient numbers for the diffusion chamber assay. Thirty one fibroblastic colonies and twenty one adipocytic colonies were isolated either by limiting dilution or ring cloning and then expanded. Of these, eleven fibroblastic and eight adipocytic colonies provided enough cells (2 x 10(5) to 2 x 10(6] for implantation and culture in the chambers. Four of the eleven fibroblastic and three of the eight adipocytic colonies formed an osteogenic tissue in the chambers. It was concluded that cells that have differentiated in an adipocytic direction are able to revert to a more proliferative stage and subsequently to differentiate along the osteogenic pathway. Adipocytic and fibroblastic cells cultured in vitro from marrow have, with osteogenic cells, a common precursor in adult marrow.

Adipose Tissue↗
PubMed1989

Sperm morphology and storage in the female reproductive tract of the fat-tailed dunnart, Sminthopsis crassicaudata (Marsupialia: Dasyuridae).

A study of spermatozoa in the isthmus of the oviduct and of the surrounding epithelial cells in the dasyurid marsupial, Sminthopsis crassicaudata, was carried out. At least 10% of the ejaculated spermatozoa probably populate the isthmus region, where many come to reside in crypts until around the time of ovulation. Ultrastructural observations of spermatozoa in this region indicated that they had intact acrosomes and were identical in their morphology with those in the cauda epididymidis. After ovulation spermatozoa rapidly disappeared, some of which may be phagocytosed by the cells lining the crypts. These epithelial cells were also found to have many large, electron-dense granules at the time of sperm storage, but the contents did not appear to be released until the zygotes passed along the tract. The secretory activity of these cells may thus relate more to the production of the shell membrane that comes to surround the zygote than to the cells performing a nutritive or protective function for the spermatozoa during their period of storage within the female reproductive tract.

Animals↗
PubMed1989

The adenylate cyclase response to parathyroid hormone in cultured rabbit marrow fibroblastic cells.

The ability of fibroblastic cells to respond to parathyroid hormone (PTH) by an increase in adenylate cyclase activity is accepted as a characteristic of the osteogenic phenotype. Whether marrow fibroblastic cells, which have osteogenic potential when assayed in vivo, demonstrate this hormonal response when cultured in vitro has been investigated. Our study has shown a level of stimulation of adenylate cyclase activity by PTH in cultured rabbit marrow fibroblasts comparable with other osteogenic cells in vitro. The effect is seen in fibroblasts grown either from multiple colonies or from single colonies. Only a proportion of colonies had osteogenic potential in vivo assay and our results show a similar finding for the PTH response in vitro. To what degree the two parameters are expressed by the same colony has not yet been established.

Adenylyl Cyclases↗
PubMed1986

Genetic variation in natural and laboratory populations of the marsupial Sminthopsis crassicaudata.

Gel electrophoresis of blood proteins has detected allelic variation at five loci (TRF, PGD, SOD, ADA, GPI) in a laboratory colony of the dasyurid marsupial Sminthopsis crassicaudata. Family data show no significant departures from Mendelian expectations. Analysis of blood from wild-caught progenitors of the colony revealed significant differences in gene frequency between groups of animals captured from different parts of southern and central Australia and showed that there are two major population clusters. These interpopulation differences are particularly marked at the TRF locus and indicate that the river Murray is a barrier for this species.

Adenosine Deaminase↗
PubMed1982

Superoxide Dismutase: A POSSIBLE PROTECTIVE ENZYME AGAINST OZONE INJURY IN SNAP BEANS (PHASEOLUS VULGARIS L.).

An experimental chemical N-[2-(2-oxo-1-imidazolidinyl)ethyl]-N'-phenylurea (EDU), is an effective protectant against acute and chronic foliar injury due to ozone (0(3)) when sprayed on intact leaves or supplied to the plants through soil application. An 0(3)-sensitive snap bean cultivar (Phaseolus vulgaris L. ;Bush Blue Lake 290') was systemically treated with EDU (0, 25, 50, and 100 milligrams per 15-centimeter diameter pot) to determine if EDU-induced or activated protective oxyradical and peroxyl scavenging enzymes. EDU-enhanced tolerance to O(3) injury always correlated with increases in superoxide dismutase (SOD) and catalase activities in the leaves. Peroxidase levels correlated more closely with foliar injury. Greater SOD levels in young leves compared to older leaves were associated with lower ozone sensitivities in these tissues.Polyacrylamide slab gel electrophoresis separations and specific determinations of SOD activity showed that EDU-treated plants possessed markedly greater SOD activity than non-treated plants. Tolerant plant tissues may have enhanced enzyme scavenging capabilities for the protection against toxic oxyradicals. Experimental confirmation for the oxyradical theory for O(3) phytotoxicity and SOD involvement in the detoxification process are presented.

Journal Article↗
PubMed1981

Retardation of Senescence in Red Clover Leaf Discs by a New Antiozonant, N-[2-(2-Oxo-1-imidazolidinyl)ethyl]-N'-phenylurea.

Dark-induced senescence in leaf discs from O(3)-sensitive red clover trifoliates (Trifolium pratense L. cv. ;Pennscott') was markedly retarded by treatment with N-[2-(2-oxo-1-imidazolidinyl)ethyl-N'-phenylurea (EDU). EDU also protects against acute and chronic foliar O(3) injury when sprayed on intact leaves or supplied to the plants through soil application. Senescence retardation was measured by time-dependent analyses of chlorophyll, protein, and RNA in discs floated on aqueous EDU solutions ranging from 0 to 500 micrograms per milliliter EDU. Chlorophyll degradation, total protein, and nucleic acids were followed over 10-day test periods.EDU at 500 micrograms per milliliter (50 milligrams per pot), a concentration known to provide optimal protection to intact leaves against O(3) injury, was most effective in preventing chlorosis and in maintaining high concentrations of protein and RNA in the discs. In discs treated with 500 micrograms per milliliter EDU 90% of the chlorophyll was retained after 10 days in the dark. In contrast, lower concentrations (0, 125, and 250 micrograms per milliliter) showed the complete loss of chlorophyll or an intermediate retardation. The intermediate concentrations were similarly less effective in maintaining protein and RNA levels in the dark stressed leaf discs. It is suggested that EDU retards senescence and mitigates O(3) injury through the induction of specific free radical scavenging enzymes and in sustaining RNA and protein synthesis.

Journal Article↗
PubMed1979

Two light sources differentially affected ferric iron reduction and growth of cotton.

In growth chambers, low pressure sodium (LPS) plus incandescent (Inc) lamps and fluorescent cool-white (FCW) plus Inc lamps were used to determine their effects on growth of cotton (Gossypium hirsutum L.) and on the reduction of Fe(3+) to Fe(2+). Cotton plants grown under LPS + Inc light developed chlorosis and grew poorly, whereas plants grown under FCW + Inc lights were green. The chlorophyll concentration and top and root weights of cotton grown under LPS + Inc were lower than those under FCW + Inc. In solution, FCW + Inc lamps reduced about eight times more Fe(3+) to Fe(2+) than did LPS + Inc lamps. Fe(3+) is transported to plant tops as Fe(3+) citrate and if we assume that FCW + Inc light reduces Fe(3+) to Fe(2+) in plant foliage as it did in the solutions, then reduction of Fe(3+) by the light environment will make Fe(2+) in the tops more available for biochemical reactions.

Journal Article↗