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Biomedical subjects

R Markham

Publications and source records attributed to R Markham.

At least 19 recordsLinked to original sources
PubMed1995

The effect of high-dose medium- and long- term progestogen exposure on endometrial vessels.

A total of 19 paraffin-embedded endometrial tissue blocks were obtained from high-dose progestogen-exposed patients. A labelled streptavidin-biotin-alkaline phosphatase method was used with antibodies against von Willebrand factor (vWF) and CD34. The density of CD34 and vWF positive (CD34+ and vWF+) vessels in progestogen-exposed endometria (103 +/- 9.6/mm2 and 106 +/- 8.7/mm2) was significantly lower than in endometria from women with normal cycles (169 +/- 9.3/mm2 and 136 +/- 8.0/mm2) (P < 0.05). In women with normal menstrual cycles the concentration of CD34+ vessels was significantly higher than the number of vWF+ vessels (P = 0.0001). By comparison, the concentration of CD34+ vessels was similar to the concentration of vWF+ vessels in progestogen-exposed endometria. The ratios of vascular density as determined by vWF+ and CD34+ staining the control and progestogen groups were 0.81 and 1.05 respectively (P = 0.0001). Dilated venules were seen in the progestogen group. This study has demonstrated firstly that CD34 antibody detected the endothelial cells in a higher proportion of small endometrial vessels than vWF, and secondly that high-dose progestogen exposure significantly decreased the density of microvessels and increased the number of dilated venules in endometrium.

Antigens, CD↗
PubMed1995

The effects of natural and synthetic sex steroids on human decidual endothelial cell proliferation.

The effects of natural and synthetic sex steroids on the proliferation of human decidual capillary endothelial cells in culture were investigated. Oestradiol at 5.0 ng/ml stimulated culture growth. Lower concentrations of oestradiol inhibited growth, while higher concentrations had no effect. Low concentrations of progesterone (5.0 and 10.0 ng/ml) had no effect on growth, while higher concentrations (20.0 and 40.0 ng/ml) inhibited growth. Combinations of oestradiol and progesterone usually reproduced the effects of progesterone alone. 3-Ketodesogestrel and levonorgestrel both inhibited endothelial cell growth, while medroxyprogesterone acetate had no effect. These findings suggest that (i) oestradiol and progesterone have direct effects on endothelial cells and are probably involved in the cyclical growth and regression of endometrial blood vessels in vivo, and (ii) the actions of certain progestogen-only contraceptives may have direct effects on endometrial blood vessels.

Capillaries↗
PubMed1995

HIV-1 p17 synthetic peptide vaccine HGP-30: induction of immune response in human subjects and preliminary evidence of protection against HIV challenge in SCID mice.

An HIV-1 p17 subunit vaccine, HGP-30, was evaluated in 38 HIV-1 seronegative individuals in phase I clinical trials in U.K. and U.S.A. The vaccine preparation induced cytotoxic T-cell (CTL) (11/25) and lymphocyte proliferation responses to KLH (19/20) and HGP-30/p17 (24/29) as well as antibody responses to HGP-30 (29/38) and KLH (38/38). The CTL activity was observed in a higher number of vaccine recipients (9/18) in the lower dose groups (10 and 25 micrograms/kg) than the vaccine recipients (2/7) in the 50 and 100 micrograms/kg dose group. These observations suggest that the 10-25 micrograms/kg vaccine dose may preferentially induce TH1 cell responses. TH1 cell responses have been suggested as important in inducing protective cell mediated immunity. The CTL response has been shown to be CD8+. In a pilot study in SCID mice, HIV-1 virus challenge studies in mice reconstituted with cells from an HGP-30 immunized individual showed protection against virus challenge as compared to SCID mice reconstituted with cells from a non-immunized subject. These studies suggest that HGP-30 is capable of inducing protective cellular immunity.

AIDS Vaccines↗
PubMed1994

A new reliable method of culturing and measuring human decidual capillary endothelial cells.

A reliable method of culturing human decidual capillary endothelial cells was developed. Endothelial growth cell supplement, heparin and newborn bovine serum were added to the culture medium to facilitate growth. Decidual capillary endothelial cell cultures showed similar growth curves to the more traditional human umbilical cord vein endothelial cell cultures. Culture growth was assessed by a new morphometric method of measuring cell culture area with the use of a computerised measuring tablet. This new method was compared with the more laborious method of counting individual cells and was found to be as reliable and more efficient.

Cell Division↗
PubMed1993

Imagery ability and source monitoring: implications for eyewitness memory.

The present study investigated the effect of self-reported vividness of visual imagery on the ability to discriminate between memories derived from two external sources of information. Subjects were shown a film of a crime and were then given a written description of the event which included information not seen in the film. In a source monitoring task, high and low imagers were found to be equally proficient in recognizing items as previously presented, but high imagers were poorer at discriminating the source of items based on the written description. This finding is considered in terms of possible encoding and retrieval differences resulting from imagery vividness. The role of vivid visual imagery as a variable underpinning confusions in eyewitness testimony is discussed.

Cues↗
PubMed1992

Relationship of human immunodeficiency virus type 1 sequence heterogeneity to stage of disease.

V3 envelope sequences were determined from amplified human immunodeficiency virus type 1 (HIV-1) sequences of uncultivated leukocytes obtained sequentially from four infected adults over the course of infection. Lower levels of sequence heterogeneity were noted in samples obtained early in HIV-1 infection, prior to CD4 depletion, than in samples obtained at later times during disease. The pattern of amino acid sequence divergence included nonrandom changes, with evidence of sequence variants arising from HIV-1 quasi-species present earlier in infection. Consensus sequences for isolates obtained early after infection from different patients demonstrated a high level of conservation with one another and a consensus sequence for macrophage-tropic HIV-1 isolates. These findings suggest that a highly restricted subset of HIV-1 quasi-species can be transmitted and can establish infection.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Individual differences in anxiety level and eyewitness memory.

The present study investigated the relationship between individual differences in anxiety and eyewitness performance. Instructions designed to produce evaluative threat were given to anxious and nonanxious subjects at encoding and/or at retrieval. The performance of those subjects who were given anxiety-arousing instructions at encoding and retrieval and who scored high on the Test Anxiety Scale (TAS; Sarason, 1972) was less accurate on an eyewitness task than was that of the subjects who scored low on the scale. This difference in performance was attributable to improvement in the performance of nonanxious subjects, rather than debilitation in the performance of anxious subjects. Faced with the threat of failure, low-anxious subjects appeared to have the potential for increased effort. High-anxious subjects seemed to perform at or near capacity under all the experimental conditions because of their predisposition for task-irrelevant worry, which limited the possibility of an increase in working memory capacity.

Adult↗
PubMed1992

Improved power control during microwave heating in biological applications.

The heating performance of prototype variable power control units attached to two domestic microwave ovens, 500 W and 700 W, was investigated. The units employed the phase control method where rated voltage was obtained by switching AC supply at a particular angular position on the sinusoidal voltage. In order to create experimental conditions employed in a previous study, Sydney tap water (50 mL) was heated at a 10% power level in the 500 W oven. Water boiled at 10 min in both experiments. However, the precision and control of the heating was greatly improved with addition of the control unit. A disinfecting solution (50 mL) and a tissue fixative (10 mL) were included for experiments with the 700 W oven. A power level of only 1% was sufficient to maintain the temperature of the fixative at low temperatures (30-40 degrees C) where many biological reactions occur. The present results indicate that microwave heating power can be controlled by the variable power control method. This will make temperature control possible through the provision of an electronic feedback loop which links a thermocouple with the power control unit.

Heating↗
PubMed1992

Lack of association between maternal antibodies to V3 loop peptides and maternal-infant HIV-1 transmission.

We investigated the association between maternal antibodies to HIV-1 peptides in pregnant women and the acquisition of HIV-1 infection by their offspring. Pregnant HIV-1-infected Haitian women were tested for the presence of antibodies against peptides of 14-17 amino acid length from the V3 loop region of strains IIIb and MN. Antibody testing was performed in two separate laboratories by enzyme-linked immunosorbent assay (ELISA). Peptides from four regions of the V3 loop were synthesized in several different laboratories and the purity confirmed by high performance liquid chromatography (HPLC). The mothers of infants who acquired HIV-1 infections did not differ significantly from the mothers of uninfected infants in the prevalence or concentration of antibodies to any of the 15 peptides evaluated. Additional studies are indicated to determine if neutralizing antibodies or other immunologic parameters are associated with maternal-infant HIV-1 transmission.

Amino Acid Sequence↗
PubMed1991

Recognition of affective facial expressions by children and adolescents with and without mental retardation.

Children and adolescents with mental retardation were compared with children and adolescents without mental retardation on their ability to recognize facial expressions. The groups were matched for either chronological age (CA) or mental age (MA). Children and adolescents with mental retardation recognized facial expressions less accurately than did subjects without retardation who were matched on CA. The MA-matched groups showed no differences in accuracy at the younger MA but a difference was found at the older MA. However, subjects categorized as having cultural-familial retardation did not differ from subjects without retardation matched for MA at either the younger or older MA. Results suggest that children with mental retardation are less able than children without retardation to develop emotional recognition skills by observational learning.

Adolescent↗
PubMed1989

Serum CA-125 levels in women with endometriosis.

Forty-two women with laparoscopically-confirmed pelvic endometriosis (assessed according to the American Fertility Society modified classification) had serum levels of the cell-surface antigen CA-125 measured before, during and after medical therapy with nafarelin acetate or danazol combined with follow-up laparoscopic surgery or laparotomy. Serum levels before treatment (39.3 [SE 6.6] U/ml) were elevated above accepted normal levels in many subjects, and these were highly significantly suppressed during medical therapy with both nafarlin and danazol (13.1 [SE 1.5] U/ml at 5 months); t = 3.198; p = 0.002). Levels tended to rise following therapy but a clear correlation between a rise in serum CA-125 and recurrence of disease was not demonstrated. In 3 individuals treated with nafarelin a dramatic rise in serum CA-125 levels was seen after 2 weeks of therapy. This did not correlate with any exacerbation of symptoms or with any rise in serum oestradiol or with pretreatment AFS scoring. Serum CA-125 levels provide a potential approach to the monitoring of treatment and recurrence in a substantial proportion of women with endometriosis, although preliminary evidence suggests that there will be individual exceptions to any broad correlations.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1989

Detailed assessment of big big prolactin in women with hyperprolactinemia and normal ovarian function.

Six women with elevated circulating levels of big big PRL (BBPRL) and apparently normal ovarian function were variously studied through a menstrual cycle and menstruation, through pregnancy and suckling, and during stimulation tests with TRH and suppression with bromocriptine. No significant changes in monomeric PRL were demonstrated during the menstrual cycle, but all subjects showed a small and significant rise in BBPRL during the preovulatory phase. High PRL levels were present in day 1 menstrual plasma, but BBPRL was only present in low concentrations. All subjects (n = 5) demonstrated a rise in both PRL and BBPRL during pregnancy, with a consistent tendency for PRL to increase to a proportionately greater extent than BBPRL. One subject exhibited a rise in PRL (by 93%), but not BBPRL, 30 min after suckling. TRH caused a brisk rise in PRL (by 363 +/- 116%) but only a sluggish rise in BBPRL (by 17.5 +/- 7.4%; n = 3). Bromocriptine rapidly suppressed PRL (by 81.8 +/- 34.4%), but only slowly suppressed BBPRL (by 21.0 +/- 8.7% after 6 h; n = 3). Plasma binding studies did not demonstrate any evidence of a circulating specific PRL-binding protein. These data indicate that plasma concentrations of BBPRL may vary under the influence of a number of factors, but are much less sensitive to TRH stimulation, bromocriptine suppression, pregnancy, and suckling than PRL. The occurrence of BBPRL does not seem to be due to a specific circulating binding protein.

Adult↗
PubMed1988

The chick chorioallantoic membrane assay: an improved technique for the study of angiogenic activity.

The chick chorioallantoic membrane assay has been used for many years as an in vivo assay of angiogenic activity. However it has been plagued with the problem of a high incidence of false positive angiogenic responses. In this study the conventional chick chorioallantoic membrane assay was compared with a modification of this technique in a series of batches using a total of 100 eggs. False positive reactions were recorded in 32 out of 50 (64%) using the conventional method and only 11 out of 50 (22%) with the modified method (chi 2 = 17.992; p less than 0.001).

Amnion↗
PubMed1987

Trauma-induced human endometrial prostaglandin concentrations.

Controversy still continues concerning the factors controlling endometrial prostaglandin concentrations measured under different circumstances. In this study an attempt was made to remove serial samples of normal human endometrium and standardise 4 different short incubation periods at room temperature before snap-freezing the tissue. No significant difference was found in the concentrations of PGE2 and PGF2 alpha, or PGE2/PGF2 alpha ratio, of the series of specimens with the shortest incubation (42.7 seconds) compared with the longest (93.1 secs). The most likely explanation for this is that trauma-induced prostaglandin production is such a rapid process that it is generally complete within less than 30 seconds at room temperature. As reported in previous studies, a significant correlation was found between PGE2 and PGF2 alpha concentrations in some specimens. Large and significant variations in concentration of prostaglandins were found between individuals which were partly accounted for by variations in stage of the menstrual cycle at the time of collection.

Biopsy↗
PubMed1986

Measured menstrual blood loss in women with menorrhagia associated with pelvic disease or coagulation disorder.

Fifty-five women with a convincing clinical history of menorrhagia associated with recognizable pelvic disease (40 women) or a confirmed coagulation disorder (15 women) were studied through one or more cycles with measurements of menstrual blood loss volume by a modified alkaline hematin method. Women with leiomyomata almost always exhibited large volumes of menstrual bleeding, which was invariably reduced by myomectomy and sometimes helped by mefenamic acid. Women with other pelvic disease such as endometriosis, adenomyosis, and myometrial hyperplasia also often exhibited genuine menorrhagia that responded to mefenamic acid, whereas others were found to have normal blood loss even when the history was convincing. Some women with coagulation disorders due to platelet dysfunction exhibited gross menorrhagia but others had blood loss within normal limits.

Blood Coagulation Disorders↗
PubMed1985

The measurement of human endometrial prostaglandin production. A comparison of two in vitro methods.

Two in vitro methods for measuring human endometrial prostaglandin production were compared. Endometrial samples from eight patients were incubated over eight hours by a perifusion and a superfusion technique. The collected fractions were assayed by radioimmunoassay for PGE2 and PGF2 alpha. There was no significant difference between the perifusion and superfusion methods for the pattern and amount of PGE2 and PGF2 alpha production with time. Significantly higher production levels of PGE2 and PGF2 alpha were found in secretory phase endometria than in proliferative phase endometria. Histological examination of the tissue specimens by light and electron microscopy showed that both methods caused gross tissue damage after eight hours experimentation. The superfusion method produced more morphological damage than the perifusion method. However, no tissue damage could be detected after one hour of incubation with either method. Over an eight hour period neither the perifusion nor the superfusion technique appears to be a good indicator of in vivo endometrial prostaglandin production. Either technique used for only one to two hours may better reflect the in vivo situation.

Dinoprost↗
PubMed1985

Blood and total fluid content of menstrual discharge.

Twenty-eight regularly menstruating female volunteers made careful collections of their sanitary pads and tampons on a daily basis throughout one menstrual period in such a way that the total fluid volume of the menstrual discharge could be accurately measured independently of the blood loss. The percentage contribution of blood (equivalent to mixed venous blood from the cubital fossa) to the total varied very greatly from woman to woman (1.6 to 81.7%) with a mean of 36.1 +/- 3.6% (+/- SEM). There was a highly significant correlation between total fluid loss and blood loss (r = 0.911, P less than .001). The proportion of blood remained approximately the same for different total volumes and on different days of the cycle. Women using no contraception or who had undergone tubal sterilization had similar ratios of blood to total fluid loss, whereas intrauterine device (IUD) users had a higher ratio (P less than .025) and oral contraceptive users a lower ratio that just reached statistical significance (P less than .05). It seems probable that the major component of the fluid loss that cannot be accounted for by blood is from endometrial tissue fluid rather than vaginal or cervical secretions.

Blood Volume↗