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Biomedical subjects

T A Ryder

Publications and source records attributed to T A Ryder.

At least 37 records · Page 2Linked to original sources
PubMed1987

Iatrogenic epithelial change caused by endotracheal intubation of neonates.

Tracheae of 20 neonates were obtained at postmortem examination. All neonates had been intubated for between 4 h and 105 days. The tracheal epithelial lining was examined by both light and scanning electron microscopy. Five tracheae which had never been intubated served as controls. All of these showed ciliation throughout their length. Those neonates who had been intubated showed epithelial change which ranged from a simple deciliation to a full stratified squamous epithelium. The degree of change was broadly related to the duration of intubation.

Cilia↗
PubMed1987

Fine structure of cells infected with human cytomegalovirus after treatment with 9-(1,3-dihydroxy-2-propoxymethyl)guanine.

Infection with human cytomegalovirus (CMV) is characterized by cytological changes which are readily visualized by electron microscopy using ultrathin sections of infected cells. Treatment of such cells with 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), a potent inhibitor of CMV, is effective when initiated at early or late times after infection and the response to such treatment has been studied by fine structural analysis. Inhibition of viral DNA synthesis by DHPG treatment (50 microM) late in virus infection resulted in a cessation of virus growth accompanied by a lack of development and possible regression in skein-like intranuclear inclusions together with a depletion in cytoplasmic dense bodies. Such changes were accompanied by the appearance of nuclear dense bodies. These were also present when virus growth was reduced (5 microM-DHPG) rather than completely inhibited (50 microM-DHPG) by treatment initiated from the time of infection. The nuclear bodies were predominantly of a reticular type structure after the early treatment but mainly of a homogeneous form when virus growth was interrupted at late times. Their presence appeared to be connected with the ability of infected cells to initiate the synthesis of late proteins and their morphology may relate to the extent of such protein synthesis. Unlike cytoplasmic dense bodies, provisional findings on the characterization of the nuclear bodies suggested that the 69K matrix protein was not present in abundance.

Acyclovir↗
PubMed1986

Effects of dydrogesterone on the oestrogenized postmenopausal endometrium.

Postmenopausal women receiving conjugated oestrogens 1.25 mg daily continuously were also given dydrogesterone either 5, 10 or 20 mg daily for the first 12 days of each calendar month. Endometrial tissue obtained on the sixth day of combined therapy in the third or subsequent treatment cycle was subjected to histological, ultrastructural and biochemical assessments. Dydrogesterone provoked secretory histological and ultrastructural changes within the endometrium in a dose-dependent manner. A daily dose of 5 mg produced sub-optimal responses but 10 and 20 mg daily produced effects similar to those observed in the secretory phase of the ovulatory cycle. Dydrogesterone 10 mg and 20 mg daily reduced epithelial DNA synthesis and nuclear oestradiol receptor levels to values within the secretory phase range. A dose-response relation was seen in the induction of oestradiol-17 beta and isocitrate dehydrogenase activities; hyperphysiological values were observed with 20 mg of dydrogesterone daily. This study has demonstrated that dydrogesterone exerts potent anti-oestrogenic and progestational effects on the human endometrium which are dose-related. The 10 and 20 mg doses induced responses equal to or greater than those observed in the secretory phase of the ovulatory cycle and both dosages can be recommended for use in combination with exogenous oestrogens in postmenopausal women: and they may also have a role in the management of anovulatory dysfunctional uterine bleeding.

Cell Nucleus↗
PubMed1986

Is Provera the ideal progestogen for addition to postmenopausal estrogen therapy?

In a dose-ranging study, medroxyprogesterone acetate, 2.5, 5, or 10 mg daily, was given for 12 days of each calendar month to postmenopausal women also receiving conjugated estrogens, 0.625 mg daily, continuously. Endometrial biopsy specimens were taken on the sixth day of combined therapy for histologic, ultrastructural and biochemical evaluation. Medroxyprogesterone acetate induced secretory and ultrastructural changes within the endometrium, but the responses were variable and inconsistent. Suppression of epithelial deoxyribonucleic acid synthesis appeared dose-dependent. The levels of nuclear estradiol receptor, although reduced to within the secretory phase range, were not significantly lower than the values observed during the estrogen-only phase of treatment. Induction of both estradiol and isocitrate dehydrogenase activities was to within the secretory phase ranges, but the magnitude of these responses appeared less than those observed previously with other progestogens. Both morphologically and biochemically, medroxyprogesterone acetate, even at high dosage, produced suboptimal responses. Further studies are required to establish whether this is a dose-related effect.

Biopsy↗
PubMed1984

Human cytomegalovirus infections in vitro after treatment with arildone.

Arildone (WIN 38020), a broad spectrum antiviral, aryl-beta-diketone (4-[6-(2-chloro-4-methoxy)phenoxyl]hexyl-3,5-heptanedione), blocks the replication of human cytomegalovirus at a stage prior to the synthesis of virus-specific DNA. Inhibitory action was demonstrated against a number of virus isolates from neonates and immune-compromised patients. Intranuclear sites of virus replication, highlighted by DNA-staining methods or immunofluorescence, were absent after Arildone treatment and corresponded with the lack of ultrastructural changes associated with productive infection. The abundance of early antigens in cells treated with Arildone was evidence for expression of the viral genome and this was confirmed by detection of immediate-early viral proteins in the presence of the drug. The results suggest that Arildone prevents the replication of human cytomegalovirus at a stage after virion uncoating but prior to viral DNA synthesis.

Antigens, Viral↗
PubMed1984

Characteristics of a new human neuroblastoma cell line which differentiates in response to cyclic adenosine 3':5'-monophosphate.

A new human cell line, TR14 , has been established in tissue culture from biopsy material of a primary neuroblastoma tumor. Most TR14 cells have short processes and grow mainly in clumps adhering to cells attached to the substratum. TR14 cells form colonies in soft agar demonstrating anchorage independence of growth and produce tumors in nude mice with histologies similar to that of the patient's tumor. The neurotransmitter-synthesizing activity of these cells is predominantly cholinergic with only a minor adrenergic component, since the activity of choline acetyltransferase is about 20-fold greater than that of tyrosine hydroxylase. Treatment with N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate induces TR14 neuroblastoma cells to extend fine, long processes or neurites. This morphological change is accompanied by elevated numbers of cytoplasmic dense-core vesicles observed by electron microscopy and an increase in the activities of neurotransmitter-synthesizing enzymes. Differentiation therefore occurs at the levels of cellular morphology, ultrastructure, and biochemistry. Prostaglandin E1 and cholera toxin can also induce differentiation, but a range of other agents including dimethyl sulfoxide, nerve growth factor, butyrate, corticosteroids, and 5-bromodeoxyuridine is ineffective. The concomitant induction of both morphological and biochemical differentiation therefore appears to be exclusively a cyclic adenosine 3':5'-monophosphate-mediated event in this cell line.

Animals↗
PubMed1983

Dose dependent effects of oral progesterone on the oestrogenised postmenopausal endometrium.

Oral progesterone 100, 200, or 300 mg daily was given for the first 10 days of each calendar month to postmenopausal women also receiving conjugated oestrogens 1.25 mg daily continuously. Endometrial biopsy specimens were taken on the sixth day of the third or subsequent cycle of combined treatment for histological, ultrastructural, and biochemical evaluation. Secretory histological changes were induced within the endometrium in a dose dependent manner, as were progesterone sensitive ultrastructural features such as nucleolar channel systems, giant mitochondria, and subnuclear accumulations of glycogen. Dose response relations were also observed for suppression of DNA synthesis and nuclear oestrogen receptor, and for induction of the activities of oestradiol and isocitric dehydrogenases. Progesterone administered by mouth clearly provokes an end organ response within the endometrium. Suboptimal effects were observed with the lower doses but progesterone 300 mg daily achieved responses approaching and within the physiological range. This dose may therefore be effective as an alternative to synthetic progestogens for therapeutic purposes.

Dose-Response Relationship, Drug↗
PubMed1983

Scanning electron microscope study of Candida albicans invasion of cultured human cervical epithelial cells.

The invasion of monolayer cultures of epithelial cells from the human uterine cervix by clinical isolates of Candida albicans was observed. Blastospores settle on the epithelial cells and produce germ tubes within 2 h. Hyphae penetrate the epithelial cell walls and destroy the cells, weaving in and out of the cytoplasm. No phagocytosis of yeast cells by epithelial cells was seen.

Candida albicans↗
PubMed1981

Effects of estrogens and progestins on the biochemistry and morphology of the postmenopausal endometrium.

To study the effects of exogenous estrogens on the postmenopausal endometrium, and to determine the time course and minimum dosage of added progestins necessary to oppose estrogen stimulation, we obtained endometrial specimens from symptomatic postmenopausal women being treated with various preparations of estrogens and progestins. Morphologic changes were assessed with light and electron microscopy, and biochemical effects through measurement of DNA synthesis, estradiol and progesterone receptors, and isocitric and estradiol dehydrogenase activity. For comparison, identical studies were carried out on specimens from premenopausal women in the proliferative and secretory phases of their cycle. All the estrogens exerted stimulatory effects in the postmenopausal specimens that were comparable to those observed in the premenopausal proliferative-phase specimens. Estropipate, subcutaneous estradiol, and conjugated estrogens had some hyperphysiologic effects. Maximal progestational effects occurred in the postmenopausal specimens only after norethindrone was administered for six days, and a constant level of activity equal to that in premenopausal secretory-phase specimens was then observed until the 10th day of exposure. Similar maximal effects occurred after six days of treatment with D/L-norgestrel (150 and 5 mg daily [10 mg daily produced less complete changes]). We conclude that many estrogen preparations subject the endometrium to a potent stimulus. Norethindrone and norgestrel are protective because they counteract the proliferative effects of estrogens, but the currently recommended daily dosages of these progestins can be greatly reduced without loss of response.

DNA↗
PubMed1980

The effect of blood flow on the surface morphology of the human endothelium.

The endothelial lining from the aortae of three 17 week human fetuses was examined by scanning electron microscopy. Orientation of the endothelial cells, particularly in the region above the aortic valve, was related to known flow patterns. Endothelial morphology showed regional variation noticeably at the mouths of arteries and at the aortic bifurcation. The possibility that this morphological change may be a hitherto unrecognised risk factor related to the site of atheromatous deposition is discussed.

Aorta↗
PubMed1980

Amine oxidase histochemistry of the human uterus during the menstrual cycle.

The enzymes monoamine oxidase A (MAO A), monoamine oxidase B (MAO B) and benzylamine oxidase (BzAO) have been locaized histochemically in the human uterus during various phases of the menstrual cycle. The results show a large increase in MAO A activity in th endometrial gland cells in the secretory phase of the cycle. MAO B activity was found in both endometrium and myometrium but did not show a cyclical variations in activity. BzAO was localized primarily in the tunica media of the myometrial blood vessels. These observations have been supported by parallel biochemical assay.s

Benzylamine Oxidase↗
PubMed1979

In vivo production of the nucleolar channel system in post menopausal endometrium.

Endometrial biopsies from seven postmenopausal women on hormone replacement therapy have been examined for the presence of the unique nuclear structure, the nucleolar channel system. Its identification in five of the patients has demonstrated that the nucleolar channel system can be produced by an appropriate oestrogen and progestagen treatment and is not otherwise dependent on ovulation.

Cell Nucleolus↗
PubMed1979

A coupled peroxidatic oxidation technique for the histochemical localization of monoamine oxidase A and B and benzylamine oxidase.

A coupled peroxidatic oxidation technique is presented which employs benzylamine and tyramine as substrates and clorgyline, deprenyl, phenelzine and pargyline as specific inhibitors. Using this technique with frozen sections of human term placenta and rat liver, the histochemical localization of monocamine oxidase A and B and bnezylamine oxidase has been demonstrated.

Animals↗