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Biomedical subjects

M R Millar

Publications and source records attributed to M R Millar.

At least 91 records · Page 5Linked to original sources
PubMed1993

Immunolocalization of oestrogen and progesterone receptors in the human decidua in relation to prolactin production.

The distribution of oestrogen and progesterone receptors within the decidualized stroma of the uterus was examined in early and term human pregnancy and the results related to the effect of oestradiol and progesterone on prolactin production by decidua in vitro. In early pregnancy progesterone receptors were present in the nucleus of decidualized cells of both the capsularis and parietalis but not in glandular cells. In contrast at term progesterone receptors were located within the cytoplasm of decidual cells. Oestrogen receptors were detected only in the nucleus and were present in greater amounts in decidua capsularis than parietalis in early pregnancy, but were not detectable in term decidua. Both oestrogen and progesterone receptors were present in the nuclei of cells of arterioles within the decidua. In early pregnancy prolactin production decreased during in-vitro culture of decidua parietalis but was maintained in decidua capsularis, associated with an increase in progesterone production by the decidua capsularis. In term decidua, prolactin production in vitro was only stimulated by a combination of oestradiol and progesterone. These results suggest, firstly, that maintained decidualization and prolactin production by decidua capsularis during treatment of women in early pregnancy with the anti-progestin mifepristone is not due to an absence of progesterone receptor; secondly, there is a shift in immunoreactive progesterone receptor in decidual cells from the nucleus in early pregnancy to the cytoplasm in term pregnancy. This may indicate an alteration in the action of progesterone around the time of parturition; and thirdly, in term decidua, progesterone, apparently acting through the cytoplasmic receptor, is active in increasing prolactin production in vitro only when combined with oestradiol.

Cells, Cultured↗
PubMed1993

Mitochondrial cytochrome C oxidase II messenger ribonucleic acid is expressed in pachytene spermatocytes at high levels and in a stage-dependent manner during spermatogenesis in the rat.

Screening of a rat seminiferous tubule library (stages VI-VIII) resulted in isolation of several clones to the same abundant mRNA. Sequencing revealed that these encoded all or part of the second subunit of cytochrome C oxidase (COX II), the terminal enzyme in the electron transport chain located in mitochondria. The pattern of expression of the COX II mRNA in the testis was examined by Northern blot and in situ hybridisation combined with specific depletion of pachytene spermatocytes or Leydig cells by treatment with methoxyacetic acid (MAA) or ethane dimethane sulphonate (EDS), respectively. COX II mRNA was found to be strongly expressed in pachytene spermatocytes in adult and prepubertal rats, with the highest levels of expression at stages VII-VIII of the spermatogenic cycle. Although this is the androgen-dependent stage, Northern analysis of total testicular RNA showed that expression of COX II mRNA was not altered detectably by EDS-induced androgen withdrawal nor was expression altered detectably by 24-h treatment with high doses of FSH. Treatment of rats with MAA, which selectively depletes seminiferous tubules at most stages of pachytene spermatocytes, resulted in a marked reduction in COX II mRNA. In the absence of pachytene spermatocytes, COX II mRNA was visualized in preleptotene spermatocytes and in Sertoli cell cytoplasm. The expression of COX II in Sertoli cells was confirmed by examination in situ of a testis devoid of most germ cells and by Northern analysis of RNA from an adult Sertoli cell-enriched preparation. However, using either approach the amount of mRNA in Sertoli cells was considerably lower than that in pachytene spermatocytes. Cytochrome C oxidase has thirteen subunits, three of which (I-III) are encoded on the mitochondrial genome. The physiological significance of the high levels of expression of COX II mRNA in pachytene spermatocytes and its stage-dependent changes is unknown but they presumably reflect requirements for alterations in energy demand as these cells enter the final stages of meiosis. The stage-dependent differences in expression of COX II mRNA in pachytene spermatocytes may also explain differences in the susceptibility of these cells to depletion by MAA.

Animals↗
PubMed1993

Skin disinfection in preterm infants.

Greater care and a more thorough approach to intravenous catheter site disinfection may be important for the prevention of catheter related sepsis, especially with coagulase negative staphylocci in preterm infants. The efficacy of skin disinfection was evaluated in preterm infants using a skin swabbing technique after disinfectant exposure. In the first part of the study, 25 peripheral intravascular catheter sites were quantitatively sampled immediately after routine cannula insertion. Bacterial counts greater than 100 colony forming units/cm2 were observed from 10 (40%) sites. In the second part, sampling for bacterial colony counts was done after skin cleansing with various durations of exposure of chlorhexidine/alcohol swabs or povidone iodine. The overall mean reduction in bacterial colony counts after skin cleansing ranged from 90-99%. Skin sterilisation was achieved in 33-92% of cases. The use of two consecutive 10 second exposures resulted in a significantly improved reduction in colony counts compared with a single 10 second wipe. A longer 30 second exposure also resulted in a greater reduction of bacterial numbers compared with a shorter duration of 5 or 10 seconds. Repopulation of disinfected sites occurred within 48 hours. This effect was delayed by occluding the cleansed site with a semipermeable dressing. There were no significant differences between povidone iodine and the chlorhexidine swabs in reducing bacterial numbers. This study has demonstrated that a brief exposure with a premoistened disinfectant swab is not sufficient for complete elimination of resident skin flora of newborn infants. The use of two consecutive cleanings, or a longer duration of cleansing is recommended for more effective skin sterilisation.

Catheterization↗
PubMed1993

Enteral feeding of premature infants with Lactobacillus GG.

The objectives of this study were to determine whether or not the probiotic Lactobacillus GG can colonise the immature bowel of premature infants and if so, does colonisation result in a reduction of the size of the bowel reservoir of nosocomial pathogens such as enterobacteriaceae, enterococci, yeasts or staphylococci, and does colonisation with Lactobacillus GG have any effect on the clinical progress and outcome. Twenty preterm infants with a gestational age of 33 weeks or less who were resident on a neonatal unit were studied from the initiation of milk feeds until discharge. The infants were randomised to receive either milk feeds or milk feeds supplemented with Lactobacillus GG 10(8) colony forming units twice a day for two weeks. The clinical features of the two groups of infants were similar. Orally administered Lactobacillus GG was well tolerated and did colonise the bowel of premature infants. However, colonisation with Lactobacillus GG did not reduce the faecal reservoir of potential pathogens and there was no evidence that colonisation had any positive clinical benefit for this particular group of infants.

Bacteria, Anaerobic↗
PubMed1993

Effects of feeding premature infants with Lactobacillus GG on gut fermentation.

The study aimed to find out whether gut colonisation of premature babies with a probiotic, Lactobacillus GG, modified enteric carbohydrate fermentation. Twenty preterm infants were randomised to receive Lactobacillus GG 10(8) colony forming units twice a day for two weeks or to a control group. Faecal short chain fatty acids (SCFAs), ethanol, and urinary 2,3-butanediol, were measured in parallel with microbiological studies. Lactobacillus GG colonised nine babies. From 1-28 days of age faecal SCFAs did not differ significantly from controls. Median and ranges were (treated and controls, respectively): acetic acid: 173 (trace-799), 166 (trace-700); propionic acid: 44 (trace-169), 37 (11-229); butyric acid: 31 (5-107), 37 (2-118) mumol/g dry weight. Ethanol was detected in more faecal samples from treated babies (65% v 37%), and at higher concentration (6.3 (trace-40) v 3.3 (0.6-8.8; one 229) mumol/g). 2,3-Butanediol was found in 66% of urine samples from treated babies and 58% from controls. On 83% of these occasions Klebsiella sp, Enterobacter sp, or Serratia sp were cultured from faeces. Lactobacillus GG had no obvious adverse effects on nutritionally important SCFAs. The small increase in ethanol excretion is unlikely to have clinical significance.

Anti-Bacterial Agents↗
PubMed1992

Stage-specific expression of rat transition protein 2 mRNA and possible localization to the chromatoid body of step 7 spermatids by in situ hybridization using a nonradioactive riboprobe.

The present study has used methoxyacetic acid (MAA)-induced depletion of specific germ cell types in the rat and in situ hybridization with nonradioactive riboprobes to determine the stages of the spermatogenic cycle at which there is expression of the mRNA for the basic chromosomal protein transition protein 2 (TP2). On Northern blots, an abundant mRNA was detectable in samples from control adult rats, but the amount of message was markedly reduced when RNA was extracted from the testes of rats treated 14 and 21 days previously with methoxyacetic acid. These testes were depleted specifically of step 7-12 spermatids, suggesting that these cells contain TP2 mRNA. When tissue sections were subjected to in situ hybridization, the TP2 mRNA was localized at the cellular and subcellular levels. Messenger RNA for TP2 was first detectable in spermatids at step 7. In these spermatids, at high magnification, in addition to some positive reaction in the cytoplasm, intense staining was located to a perinuclear structure consistent with localization of mRNA within the chromatoid body. The amount of TP2 mRNA in the cytoplasm increased as remodelling of the early spermatid nucleus progressed and was highest in step 10 and 11 spermatids at stages X and XI. Thereafter, the mRNA decreased until it was undetectable in step 14 spermatids at stage XIV. The localization of TP2 mRNA to the chromatoid body of step 7 spermatids would be consistent with this organelle being a storage site for long-lived mRNAs utilized later in spermiogenesis.

Animals↗
PubMed1992

Bactericidal activity of antimicrobial agents against slowly growing Helicobacter pylori.

The doubling times of bacteria at sites of colonization or infection are considerably longer than those in laboratory culture media, and slow growth reduces the susceptibility of bacteria to antimicrobial agents. Helicobacter pylori is susceptible to a wide range of antimicrobial agents in vitro; however, tests for inhibitory activity do not adequately predict which antimicrobial agents will eradicate slowly growing H. pylori from the stomachs of patients. The chemostat can be used to compare the bactericidal activities of antimicrobial substances against slowly growing bacteria. In this study we compared the bactericidal activities of antimicrobial agents against slowly growing H. pylori. The bactericidal activities of erythromycin, minocycline, ampicillin, amoxicillin, cefixime, metronidazole, and bismuth subcitrate against slowly growing H. pylori NCTC 11,637 in a chemostat were compared. Antimicrobial agents were added to the system at four to eight times the MIC. Exposure of H. pylori to metronidazole was associated with the rapid development of metronidazole resistance, preventing assessment of the bactericidal activity of metronidazole. Resistance to the other antimicrobial agents tested did not develop. The poor bactericidal activities of the antimicrobial agents against slowly growing H. pylori may be a contributory factor in limiting their clinical efficacies. Of the agents tested, only amoxicillin and bismuth subcitrate showed bactericidal activity against slowly growing H. pylori. The chemostat allows comparison of the bactericidal activities of antimicrobial agents against slowly growing H. pylori and may therefore provide results which more accurately identify those agents or combinations of agents that will eradicate H. pylori from patients.

Anti-Bacterial Agents↗
PubMed1992

Enterobacteriaceae and neonatal necrotising enterocolitis.

A comparative study of bowel colonisation and incidence of necrotising enterocolitis in neonates admitted to an intensive care unit is reported. Neonates of less than 33 weeks gestational age requiring mechanical ventilation for respiratory distress syndrome were randomised during the first week of life to receive either vancomycin and aztreonam or vancomycin and gentamicin for episodes of suspected sepsis after the first week of life. A higher proportion of neonates who received vancomycin and gentamicin had faecal colonisation with enterobacteriaceae at the end of the second, third, and fourth weeks of life. Treatment with vancomycin and aztreonam was associated with a rapid quantitative reduction in faecal colonisation with enterobacteriaceae, whereas there was no quantitative reduction in colonisation with enterobacteriaceae associated with treatment with vancomycin and gentamicin. There were no differences between the two groups in faecal colonisation with anaerobes, Enterococcus sp, Staphylococcus sp, or yeasts. Six (14.6%) of 41 who received vancomycin and gentamicin compared with 0 of 40 who received vancomycin and aztreonam subsequently developed necrotising enterocolitis.

Aztreonam↗
PubMed1992

Development of cutaneous microflora in premature neonates.

Coagulase-negative staphylococci (C-NS) are a frequent cause of bacteraemia in premature neonates. It is likely that the strains of C-NS causing bacterial sepsis in premature neonates have their origin on the patient's skin surface. We have studied the quantitative development of the skin microflora at eight sites on premature neonates. A swab wash method was used to sample and enumerate the cutaneous microflora of premature neonates admitted to an intensive care unit with respiratory distress syndrome. The numbers of bacteria present on the skin increased rapidly by 100-fold in the first week of life. The species of C-NS found on neonatal skin were similar to those found on adult skin. However, the bacterial population was 10(3) lower by comparison. There was considerable variation in numbers of bacteria and in the proportion resistant to antibiotics from day to day. There appeared to be no association between antibiotic usage and the proportion of isolates resistant to antibiotics, although the resident bacteria were in many cases resistant to a variety of antibiotics. C-NS were isolated from 92% of samples from which bacteria were isolated. Staphylococcus epidermidis was found at all sites and accounted for 82% of each colonial type of staphylococcus isolated. Other organisms isolated included Propionibacterium sp, alpha-haemolytic streptococci, aerobic spore-bearing bacilli, aerobic coryneforms, Candida albicans, Klebsiella oxytoca, Pityrosporum sp, Klebsiella pneumoniae, and Escherichia coli. The results of this study suggest that the skin of premature neonates is colonised with antibiotic resistant C-NS during the first week of life and that the chance of contamination of an intravascular catheter at insertion increases during this period.

Coagulase↗
PubMed1992

Effect of physical environment on survival of Helicobacter pylori.

AIMS: To determine the effects of physical conditions on survival of Helicobacter pylori in aquatic environments. Survival for prolonged time intervals would implicate environmental water as a possible source of infection. METHODS: The effect of ionic strength, pH, urea, protein and composition of incubation atmosphere on the survival of H pylori NCTC 11637 and two clinical isolates (CI 82 and 92) was investigated. RESULTS: H pylori strains survived for longer periods in physiological (0.15M) saline than in 0.05M or 0.6M saline solution. Optimal pH range for survival was between pH 5.8 and 6.9. Addition of urea (final concentration 100 microM/l-1 and 5 mM/l-1) to neutral unbuffered 0.15M saline resulted in a reduction in survival; addition of bovine serum albumin (1%) or gelatin (1%) resulted in variable survival times compared with saline alone. Incubation in a microaerobic gas mixture prolonged survival compared with incubation in air. CONCLUSION: H pylori survival in water over a prolonged period is possible for a range of physical variables. The results indicate that H pylori could survive in environmental water which may thus act as a potential reservoir of infection.

Disease Reservoirs↗
PubMed1991

Development of the transdermal potential of human skin.

The development of the transdermal electrical potential (TDP) with postnatal age was studied in neonates born at gestational ages of 25 to 42 wk. The TDP of neonates born at less than 28 wk gestational age was of similar magnitude over the whole skin surface when measured in the first 5 d of life (mean value -5.4 mV; skin surface negative with respect to s.c. tissues). The TDP increased progressively with increasing gestational and postnatal age. The rate of increase of the TDP with postmenstrual age was not accelerated in neonates born prematurely. TDP values of infants born at term were lower than those of adults, but the sites of high and low TDP were similar in both term infants and adults.

Adult↗
PubMed1991

Localization of the sites of synthesis and action of prolactin by immunocytochemistry and in-situ hybridization within the human utero-placental unit.

While the fetal pituitary synthesizes and releases prolactin, it is also produced within the utero-placental unit during pregnancy in women and has been localized in the amnion, chorion and decidua. However, it is not clear whether prolactin is synthesized within all these non-fetal pituitary tissues. We have investigated prolactin production and its gene expression using tissue culture, immunocytochemistry and in-situ hybridization techniques. Prolactin was immunolocalized not only in the decidua but also in amnion and trophoblast cells. In contrast, the in-situ hybridization results showed that silver grains, formed by specific hybridization of a prolactin cDNA probe to prolactin mRNA, were confined to decidual cells of early and term pregnancy. The results from tissue cultures correlated well with those of in-situ hybridization, that is that only the decidua made detectable prolactin, while it was undetectable in the culture medium from trophoblast tissue, irrespective of the stage of pregnancy. This study, for the first time, establishes that only decidualized cells are involved in biosynthesis of prolactin; other prolactin-containing cells in the amnion and trophoblast appear to sequester prolactin, possibly via receptors, suggesting that prolactin may play an important paracrine role within the amnion and syncitio- and cytotrophoblast of the utero-placental unit.

Blotting, Northern↗
PubMed1991

Immunocytochemical localization of inhibin alpha-subunit in the human corpus luteum.

The localization of inhibin alpha-subunit within the human corpus luteum was investigated. The antiserum used was raised in sheep against the first 1-23 amino acid sequence of the N-terminus of the human inhibin alpha-subunit. Using the avidin-biotin immunoperoxidase technique, intense immunostaining was localized within the granulosa-lutein cells of the corpus luteum, with absence of staining in the theca-lutein cells and surrounding ovarian tissue. Similar distribution of inhibin alpha-subunit immunostaining was observed in 12 corpora lutea obtained during the early, mid- and late-luteal phases and no changes in intensity were apparent at these different stages. Negative controls were obtained by applying antiserum which had been preabsorbed overnight with excess inhibin peptide in place of primary antiserum and also normal nonimmune sheep serum as a substitute for primary antiserum. These results provide further evidence that the human corpus luteum is a significant source of immunoreactive inhibin during the normal human menstrual cycle. The specific localization within the granulosalutein cells of the corpus luteum suggests that inhibin alpha-subunit production may originate from a discrete cell population within the human corpus luteum.

Corpus Luteum↗
PubMed1990

Swab-wash method for quantitation of cutaneous microflora.

We describe a comparison of the scrub-wash method of Williamson and Kligman and a swab-wash method for the enumeration of cutaneous microflora. The swab-wash method provides a less traumatic alternative to the scrub-wash method and can be used to sample the cutaneous microflora of premature neonates.

Candida albicans↗
PubMed1990

Quantitative changes in faecal microflora preceding necrotising enterocolitis in premature neonates.

Quantitative studies of faecal bacterial flora were carried out during the week preceding the clinical onset of 12 episodes of neonatal necrotising enterocolitis. There were considerable quantitative changes in the faecal flora preceding the clinical onset of both definite and possible episodes of necrotising enterocolitis. There was a decline in the numbers of some species from up to 72 hours before the clinical onset of the disease. Enterobacteriaceae were isolated from samples collected during the 48 hours preceding the clinical onset of all four definite episodes of necrotising enterocolitis. These were 'new' isolates in two episodes, and considerably increased numbers in another. The changes that we found are probably the result of changes in intraluminal conditions that precede the clinical onset of necrotising enterocolitis.

Bacteria↗