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Biomedical subjects

L Martin

Publications and source records attributed to L Martin.

At least 541 records · Page 30Linked to original sources
PubMed1979

Varying effects of an IUD on decidualization in mice.

Chronically implanted IUDs consisting of silk suture threads induced decidualization in regions of the uterus remote from the suture site in ovariectomized mice treated with a regimen of progesterone and oestrogen which sensitizes the uterus to a decidual stimulus. In these conditions the IUDs did not inhibit decidualization induced by instilled oil, although they did so in pregnant animals of the same strain. Varying the dose of progesterone and oestrogen did not produce conditions in which IUD's inhibited oil-induced decidualization in ovariectomized mice and progesterone treatment did not prevent IUDs inhibiting decidualization in pregnant animals. However, when ovariectomized mice, sensitized as before, were primed repeatedly with oestrogen to simulate continuing oestrous cycles after IUD insertion, the IUD's inhibited oil-induced decidualization. This involved the premature loss of instilled oil from the uterine lumen and was associated with heavy infiltration of leucocytes into the luminal epithelium. Numbers of leucocytes free in the uterine lumen did not appear to be critical. It appears that contact between the oil and the luminal epithelial surface must be sustained for some length of time to induce a decidual reaction; brief contact is not sufficient to trigger the response.

Animals↗
PubMed1979

Early cellular changes and circular muscle contraction associated with the induction of decidualization by intrauterine oil in mice.

Intrauterine instillations of oil or saline distended the uterus in ovariectomized mice treated with progesterone + oestrogen to sensitize the uterus to a decidualizing stimulus. Saline does not induce decidualization, and therefore uterine distension per se is not the trigger to decidual induction. Oil induces decidualization, but does not involve gross damage to the epithelium, penetration of oil into the stroma or release of epithelial lipid into the stroma. Instillation (oil, saline or sham) induced a contraction of the circular muscles along the length of the uterus which closed the uterine lumen, expelled most of the oil and located the remainder primarily in the antimesometrial cleft of the lumen. Progesterone inhibited longitudinal muscle contraction and facilitated circular muscle contraction. These effects are discussed in relation to the spacing and implantation of blastocysts.

Animals↗
PubMed1979

A simple method for removing the luminal epithelium of the mouse uterus for biochemical studies.

The luminal epithelium of the mouse uterus was removed simply and rapidly by opening the uterine horns longitudinally and 'vortexing' them in buffer with glass balls. This procedure, which requires no specialized apparatus, was developed for use with uteri in different hormonal states, and 2 uterine horns/tube, 5 glass balls and vortexing for 2 min are suggested for routine use. Under these conditions, 79--100% of the cells were removed, yielding epithelial fractions of 65--90% purity. The suspension of cell constituents recovered contained intact nuclei which could be further purified. Extensive histological examination demonstrated that the other uterine tissues were minimally damaged.

Animals↗
PubMed1978

Scanning electron microscope study on flat type membrane oxygenator after prolonged extracorporeal circulation.

Despite adequate anticoagulation, thrombi may develop onto any foreign surface subjected to circulating blood. Although the efficiency of membrane oxygenators can decrease, distal embolization can be more critical and dangerous. Scanning electron microscope observations carried out on the Travenol Modulung oxygenator used both on dogs and on patients for prolonged partial cardiopulmonary by-pass pointed out the following observations. Caution must be observed when translating the results from dogs to human beings. Heparin management can be delicate and critical. The problem of blood transfusion can be extremely important and must be extensively investigated.

Adult↗
PubMed1978

Uterine DNA synthesis and cell proliferation during early decidualization induced by oil in mice.

[3H]Thymidine autoradiography was used to study cell proliferation during decidualization induced by intraluminal oil in ovariectomized mice treated with oestrogen and progesterone. Development of the decidual reaction involves two distinct populations of stromal cells. Periluminal cells start to synthesize DNA 11--15 h after instillation and by 17--20 h, without dividing, differentiate into epithelioid decidual cells which continue to incorporate [3H]thymidine, presumably becoming polyploid. Cells peripheral to this zone also start to synthesize DNA between 11 and 15 h, but at 18.5 h many have divided before differentiating. None of these dividing cells had been arrested in G2. The periluminal and peripheral cells do not appear to differ in their proliferative antecedents.

Animals↗
PubMed1978

Prolonged oestrogenic and mitogenic activity of tamoxifen in the ovariectomized mouse.

A dose of tamoxifen (ICI 46,474), which has been found to inhibit the vaginal smear response to oestrogens, exerted prolonged oestrogenic effects in mice and increased the rate of cell proliferation in both the vagina and uterus. The vaginal epithelium became multilayered with stratified or cornified surface layers and the uterus developed gross cystic glandular hyperplasia. This demonstrates that ICI 46,474 is simply a weak oestrogen in the mouse.

Animals↗
PubMed1978

Effects of an intra-uterine device on uterine cell division and epithelial morphology in ovariectomized mice treated with oestrogen and progesterone.

Silk threads placed in the uteri of ovariectomized mice increased cell proliferation in all tissues including regions of the uterus remote from the site of insertion. Many of the effects resembled those produced by oestrogens. An intra-uterine device (IUD) increased luminal and glandular mitosis and produced various degrees of luminal epithelial hyperplasia in untreated animals. In progesterone-treated mice bearing IUD's, luminal and stromal mitosis was increased. Epithelial morphology was not affected or luminal mitosis inhibited in oestrogen-treated animals with IUD's, but stromal and glandular mitosis was increased. After combined treatment with progesterone and oestrogen, stromal mitosis was suppressed at the contact site but was increased elsewhere. Both oestrogen and progesterone suppressed the luminal leucocytosis induced by the IUD. Despite this, the IUD prevented complete progestational differentiation of the luminal epithelium and closure of the lumen. The degree to which IUD-induced abnormalities were observed depended on the hormonal status of the animal at the time of sampling.

Animals↗
PubMed1978

Effects of a long-acting progestin on reproductive function in female mice.

The duration of activity of a long-acting progestin, medroxyprogesterone acetate, was compared using three tests for progestational activity: the induction of stromal mitosis in the endometrium, implantation of blastocysts and inhibition of ovulation. The duration of activity was similar in each test and was longer when higher doses were given.

Animals↗
PubMed1978

Endothelial lesions associated with vascular clamping--surface micropathology by scanning electron microscopy.

The endothelial cell pavement in normal blood vessels is very fragile. In cardiovascular surgery, the need for secure clamping of the aorta results in trauma which may be followed by thrombosis or occlusion. Various types of vascular clamps and other related devices offered commercially were clinically investigated in canine models and their effects on the vascular endothelium were ascertained with the aid of scanning electron microscopy. On the basis of these studies, the Fogarty silicone filled clamp appeared to be the least traumatic. However, further technical developments in this area are needed in order to obtain a completely atraumatic method of temporarily closing major blood vessels.

Animals↗
PubMed1978

Albuminated dacron protheses as improved blood vessel substitutes.

An improved vascular graft was achieved by treating knitted Dacron prostheses with cross-linked albumin. Eight segments, each six centimeters in length, were coated and implanted in the canine thoracic aorta for periods ranging from 24 hours to six months. The results were compared with the eight untreated grafts implanted for similar periods as control experiments. Albumin coating resulted in a faster healing : cells appeared earlier and collagen development was greater. The most beneficial effect of that treatment was the reduction in embolization, as shown by the considerable decrease in kidney damage.

Animals↗