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Biomedical subjects

L O'Connor

Publications and source records attributed to L O'Connor.

At least 19 recordsLinked to original sources
PubMed1996

AbiG, a genotypically novel abortive infection mechanism encoded by plasmid pCI750 of Lactococcus lactis subsp. cremoris UC653.

AbiG is an abortive infection (Abi) mechanism encoded by the conjugative plasmid pCI750 originally isolated from Lactococcus lactis subsp. cremoris UC653. Insensitivity conferred by this Abi manifested itself as complete resistance to phi 712 (936 phage species) with only partial resistance to phi c2 (c2 species). The mechanism did not inhibit phage DNA replication. The smallest subclone of pCI750 which expressed the Abi phenotype contained a 3.5-kb insert which encoded two potential open reading frames. abiGi (750 bp) and abiGii (1,194 bp) were separated by 2 bp and appeared to share a single promoter upstream of abiGi. These open reading frames showed no significant homology to sequences of either the DNA or protein databases; however, they did exhibit the typical low G+C content (29 and 27%, respectively) characteristic of lactococcal abi genes. In fact, the G+C content of a 7.0-kb fragment incorporating the abiG locus was 30%, which may suggest horizontal gene transfer from a species of low G+C content. In this context, it is notable that remnants of IS elements were observed throughout this 7.0-kb region.

Amino Acid Sequence↗
PubMed1995

Relation of activity levels to body fat in infants 6 to 12 months of age.

We examined longitudinally the relation between body fatness and physical activity, adjusting for energy intake, in 31 healthy white infants. Measures of physical activity, dietary intake, and body composition were obtained at 6, 9, and 12 months of age. The percentage of body fat was inversely related to activity level, an association that became stronger with increasing age and remained significant after adjustment for dietary energy intake. The percentage of body fat was not related to energy consumed per lean body mass regardless of high or low activity level, nor was energy consumed related to physical activity. We conclude that the percentage of body fat in infants may be related more to their activity levels than to their energy intake.

Adipose Tissue↗
PubMed1995

Pain assessment by patients and nurses, and nurses' notes on it, in early acute myocardial infarction. Part I.

Pain is a multi-dimensional phenomenon unique to each individual. Most of the research to date on acute pain has focused on oncology, medical and surgical patients. This pilot study was designed to explore the issues of pain assessment by patients and nurses in acute myocardial infarction, and the nurses' subsequent documentation of the pain assessment. Three research instruments were chosen to elicit the information required: A demographic questionnaire was constructed to elicit relevant data on patients and nurses. The Short Form McGill Pain Questionnaire (SFMPQ) was used to measure the quality and quantity of the patient's pain as perceived by the patient and nurse in a myocardial infarction situation. The Chart Audit Information Form (CAIF) was chosen to extract specific information from the nursing notes on the pain experience as recorded by the nurse. A convenience sample of patients comprised 10 males and 5 females. The nursing population comprised a convenience sample of 8 registered nurses holding a recognised coronary care course certificate. The pilot study was conducted in a coronary care unit (CCU) in a large teaching hospital in Dublin, Ireland. The data generated from the SFMPQ and the CAIF were coded prior to computerisation. Descriptive statistics were used to analyse the data. The findings of this pilot study indicated that nurses underestimated the patient's pain in 46% of myocardial infarction situations and overestimated in 13% of them. Furthermore, results indicated that while the majority of nurses documented location and verbal statements of pain, the documentation of quality, intensity and duration of pain was inadequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1995

Adverse effects of paternal opiate exposure on offspring development and sensitivity to morphine-induced analgesia.

We have shown previously that chronic morphine administration to adolescent male rats produced a number of gender specific deficits in their offspring. The purpose of the present studies was to extend our earlier observations by examining the acute, direct effects of morphine exposure to male rats on their fertility and the development of viable offspring. Sexually mature male rats were injected with a single dose of morphine (25 mg/kg) and 24 hr later were bred with drug-naive females. Fertility rates (vaginal plugs and pregnancies) were monitored throughout the breeding period as was the development of the offspring. Our results showed that a large, acute dose of morphine given to drug-naive male rats 24 hr before the initiation of breeding had no effect on fertility rates, but produced several adverse effects on fetal outcome. Litter sizes in morphine-derived offspring were considerably smaller than in controls and mortality rates were more than 6 times higher. Moreover, morphine-derived male, but not female, offspring had a significantly enhanced sensitivity to the antinociceptive effects of morphine. Collectively, these data suggest that acute paternal morphine exposure just before breeding with drug-naive females had no effect on fertility, but exerted negative effects on the viability and development of their offspring. These results represent the most compelling evidence to date that paternal opiate exposure can adversely affect fetal outcome and are particularly striking in that they were produced by a single injection of morphine. We are aware of no animal studies, clinical cases or anecdotal reports in humans in which such a phenomenon has been described.

Analgesia↗
PubMed1994

Acute alcohol exposure markedly influences male fertility and fetal outcome in the male rat.

Although it is recognized that drugs ingested by pregnant females produce marked cognitive and physiological deficits in their offspring, the possibility that paternal exposure to drugs prior to mating may have adverse effects on fertility and fetal outcome has not received much attention. The purpose of the present studies was to examine whether a single, acute exposure to alcohol influences the subsequent ability of adult male rats to mate and produce healthy and viable litters. Our results showed that a relatively large dose of alcohol 24 hours prior to breeding had little effect on the mating behavior of male rats, but there were markedly fewer pregnancies in females mated with alcohol-exposed male rats than in controls. Of equal importance, we found that, even when conception occurred and live births were produced, there were striking differences in fetal outcome. Alcohol-treated males sired many fewer pups than control males and there was a markedly enhanced mortality rate in their offspring. Collectively, these data suggest that acute paternal alcohol administration 24 hours prior to breeding does not affect mating behavior, but results in a greatly diminished fertility rate and fewer and less viable offspring. These studies suggest that paternal alcohol use may be as important as maternal alcohol abuse as a negative variable in pregnancy and fetal outcome.

Animals↗
PubMed1993

Efficacy of postoperative pain treatment regimens using both buprenorphine and papaveretum sequentially after abdominal hysterectomy.

We have undertaken a double-blind, controlled study to test the hypothesis that the efficacy of standard postoperative analgesia by papaveretum or buprenorphine is not compromised by previous or subsequent standard doses of the other agent. After total abdominal hysterectomy under a standardized general anaesthetic, 120 patients (four groups of 30) were allocated randomly to receive, on demand, a single i.v. dose of buprenorphine 0.15 mg or papaveretum 10 mg, followed sequentially by a single dose of i.m. buprenorphine 0.3 mg or papaveretum 20 mg. Three hours after the i.m. dose, all patients received sublingual buprenorphine 0.4 mg. Pain was scored using both a 10-cm horizontal visual analogue scale (VAS) and a nominal scale. Pain intensity differences and patient and nurse satisfaction with the regimens were recorded. Observations were continued for 8 h after operation. The efficacy of papaveretum or buprenorphine was not compromised by previous or subsequent standard doses of the other agent. All four treatment regimens were similarly well tolerated and gave acceptable analgesia in the immediate postoperative period.

Adolescent↗
PubMed1993

A new focus of scrub typhus in tropical Australia.

A new focus of scrub typhus (Rickettsia tsutsugamushi) is described in a remote rain forest region of the Northern Territory of Australia. Five serologically confirmed cases, two near fatal with multisystem involvement, have occurred since the area became accessible to tourists. As tourism increases, other remote foci of vectors and organisms may also be recognized in tropical Australia.

Adult↗
PubMed1993

Naloxone does not reverse the inhibitory effect of morphine on luteinizing hormone secretion in prepubescent male rats.

Morphine and naloxone exert age-dependent effects on secretion of luteinizing hormone (LH) in the male rat. Morphine suppresses LH secretion at very early stages of development, well before puberty, whereas naloxone does not increase LH until after puberty. The mechanisms underlying these age-dependent effects of opiates on the hypothalamic-pituitary-gonadal axis in pre- and postpubertal rats are poorly understood at the present time. The purpose of the present studies was to examine one plausible explanation of these effects: that morphine and naloxone act through different receptors in the pubescent male rat than they do in adults to influence LH secretion. Specifically, we examined whether naloxone blocks the effects of morphine on LH in prepubescent and adult rats which would be anticipated if both drugs were exerting their effects on LH via the same opiate receptor. Surprisingly, we found that naloxone did not reverse the effects of morphine on serum LH levels in the prepubescent animal, although it fully reversed this effect in adults. This non-naloxone-reversible effect of morphine appeared to be specific to LH, since naloxone antagonized morphine's effects on several other hormones (e.g., prolactin and corticosterone) and completely attenuated morphine's antinociceptive activity in prepubescent rats. Additionally, naloxone precipitated a withdrawal syndrome in the prepubescent morphine-dependent animal that was quantitatively and qualitatively the same as in adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1992

Life cycle issues affecting cancer rehabilitation.

Developmental stage of the person with cancer has a profound effect on the rehabilitation plan. Although the issues faced by the very young and the elderly are quite different, the struggle to maintain optimal function is universal. As we continue to see improved survival rates and cures, the need for comprehensive rehabilitative care for all persons experiencing cancer becomes a challenge. Our success in meeting this challenge will be realized in measurable outcomes that will direct future rehabilitative care.

Aged↗
PubMed1991

Influence of morphine exposure during adolescence on the sexual maturation of male rats and the development of their offspring.

The effects of adolescent morphine exposure on the sexual maturation of male rats, their reproductive capacity and the development of their progeny were examined. Groups of prepubescent male rates (25-27 days of age) were implanted with morphine- or placebo-pellets (one on Day 1, then two pellets on Days 4, 7 and 10); the pellets were not removed to assure the sustained release of morphine for 3 to 4 weeks and to avoid the confounding effects of a precipitated withdrawal syndrome. Groups of animals were sacrificed at weekly intervals through adulthood for an assessment of reproductive endocrine function. A large group, however, was also bred with drug-naive primiparous females at 85 days of age (8 weeks after morphine or placebo pellet implantation), when the acute and chronic effects of morphine on reproductive endocrine parameters had dissipated; their fertility and the development of the male and female progeny was characterized. Our results indicated that morphine exposure during adolescence led to a pronounced inhibition of a number of indices of sexual maturation (e.g., serum testosterone and luteinizing hormone levels and reduced weights of the testes and seminal vesicles). Breeding morphine- and placebo-implanted male rats with drug-naive females resulted in smaller liters derived from morphine-treated fathers when compared to controls, but in all other respects the development of the offspring in the two groups were equivalent. However, upon reaching adulthood, a number of selective endocrine differences were detected in morphine-derived offspring when compared to controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A specific inhibitor of the ubiquitin activating enzyme: synthesis and characterization of adenosyl-phospho-ubiquitinol, a nonhydrolyzable ubiquitin adenylate analogue.

A nonhydrolyzable analogue of ubiquitin adenylate has been synthesized for use as a specific inhibitor of the ubiquitination of proteins. Ubiquitin adenylate is a tightly bound intermediate formed by the ubiquitin activating enzyme. The inhibitor adenosyl-phospho-ubiquitinol (APU) is the phosphodiester of adenosine and the C-terminal alcohol derived from ubiquitin. APU is isosteric with the normal reaction intermediate, the mixed anhydride of ubiquitin and AMP, but results from the replacement of the carbonyl oxygen of Gly76 with a methylene group. This stable analogue would be expected to bind to both ubiquitin and adenosine subsites and result in a tightly bound competitive inhibitor of ubiquitin activation. APU inhibits the ATP-PPi exchange reaction catalyzed by the purified ubiquitin activating enzyme in a manner competitive with ATP (Ki = 50 nM) and noncompetitive with ubiquitin (Ki = 35 nM). AMP has no effect on the inhibition, confirming that the inhibitor binds to the free form of the enzyme and not the thiol ester form. This inhibition constant is 10-fold lower than the dissociation constants for each substrate and 30-1000-fold lower than the respective Km values for ubiquitin and ATP. APU also effectively inhibits conjugation of ubiquitin to endogenous proteins catalyzed by reticulocyte fraction II with an apparent Ki of 0.75 microM. This weaker inhibition is consistent with the fact that activation of ubiquitin is not rate limiting in the conjugation reactions catalyzed by fraction II. APU is similarly effective as an inhibitor of the ubiquitin-dependent proteolysis of beta-lactoglobulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Monophosphate↗
PubMed1990

Evaluation of the RheumaStrip ANA profile test: a rapid test strip procedure for simultaneously determining antibodies to autoantigens U1-ribonucleoprotein (U1-RNP), Sm, SS-A/Ro, SS-B/La, and to native DNA.

The "LipoGen RheumaStrip ANA Profile" test method (LipoGen, Inc.) is a new assay format for autoantibody detection in which recombinant autoantigens are used. This enzyme immunoassay, in test-strip format, detects antibodies to autoantigens U1-ribonucleoprotein (U1-RNP), Sm, SS-A/Ro, SS-B/La, and to native DNA (nDNA). We evaluated 200 antinuclear antibody (ANA)-positive and 100 ANA-negative sera for the presence of antibodies to U1-RNP, Sm, SS-A/Ro, SS-B/La, and nDNA by the new test-strip procedure. These data correlated well with those obtained with either Ouchterlony double immunodiffusion for U1-RNP, Sm, SS-A/Ro, and SS-B/La or with Crithidia luciliae indirect immunofluorescence for anti-nDNA. Assay sensitivity and assay specificity of the ANA Profile method as compared with those of established procedures were respectively as follows: 89.8% and 98.8% for U1-RNP, 86.4% and 95.3% for Sm, 97.9% and 89.3% for SS-A/Ro, 98.3% and 86.3% for SS-B/La, and 97.5% and 93.1% for nDNA. Agreement between the ANA Profile test and these other test methodologies ranged from 88.7% for the SS-B/La test to 97.3% for the U1-RNP test. This new test procedure substantially decreases the time and effort required to perform these assays. Total hands-on time and overall assay time were decreased by 72% and 97%, respectively.

Antibodies↗
PubMed1990

Japanese encephalitis and the traveller.

Japanese encephalitis is a mosquito borne arbovirus disease that is endemic over a wide area of Asia, India, and the south eastern USSR. The disease is associated with a severe encephalitis, a high death rate and a high incidence of neurological sequelae in survivors. While natives of endemic areas may develop immunity, Western travellers are at risk. To date there have been two reported cases of Japanese encephalitis in people returning to Australia from overseas. A vaccine against Japanese encephalitis is available.

Encephalitis, Japanese↗
PubMed1990

Influence of chronic alcohol administration on representative indices of puberty and sexual maturation in male rats and the development of their progeny.

The effects of chronic alcohol administration on reproductive endocrinology in the developing male rat were examined. Prepubescent male rats (25 days of age) were maintained on an alcohol liquid diet or were pair-fed a control diet until early adulthood and selected indices of sexual maturation were examined at weekly intervals. To determine whether sexually immature animals were more sensitive to the effects of alcohol than adults, fully mature male animals were exposed to an identical period of alcohol exposure and comparisons were made between the two groups. The results demonstrated that alcohol significantly affected many of the primary indices of puberty and sexual maturation. The normal pubertal increases in serum testosterone levels, the weights of the testes and secondary sex organs and beta-endorphin levels in the hypothalamus were substantially reduced in alcohol-exposed animals compared with controls. In contrast to these results, the effects of alcohol on reproductive endocrinology in the fully mature animal were transitory and of considerably less magnitude. After a 2-week alcohol-free period, male rats exposed to alcohol during development were bred with drug-naive primiparous females. Although the same number of pregnancies resulted from matings between alcohol-exposed males and drug-naive females compared with controls, litter sizes were significantly smaller in alcohol-derived offspring than in controls. In all other respects, such as body weights, sex ratios, mortality rates and gross developmental features (eye opening, incisor eruption and testes descent), alcohol-derived offspring were identical with controls. Upon closer examination, however, significant disturbances were detected in alcohol-derived male offspring.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Castration-induced changes in the response of the hypothalamic-pituitary axis to alcohol in the male rat.

In an attempt to determine the direct effects of alcohol on the hypothalamic-pituitary aspect of the hypothalamic-pituitary-gonadal axis, we examined the effects of alcohol on serum luteinizing hormone (LH) levels in the normal and testosterone-depleted castrated male rat. We found that within several days after castration (2-4 days) alcohol, at low to moderate doses, was only modestly effective in suppressing serum LH levels, whereas in sham-operated controls it was maximally effective at all doses tested. Surprisingly, at very high doses (4-6 g/kg), alcohol not only did not depress serum LH levels in long-term castrated rats, but elevated them by 2- to 4-fold when compared to saline-injected controls. The loss of sensitivity of the hypothalamic-pituitary axis to alcohol observed in castrated rats appeared to be selective, inasmuch as the mortality rate at high doses of alcohol was significantly (P less than .01) greater in castrated rats, when compared to sham-operated controls, and other measures of central nervous system impairment were equivalent in both groups. At the present time, it is difficult to explain this biphasic effect of alcohol on serum LH in the castrated animal, but our results are consistent with the hypothesis that the effects of alcohol on gonadotropin release may be dependent to a significant degree on the steroid milieu at the time of the experiments.

Aldehyde Dehydrogenase↗
PubMed1990

Rabies and the traveller.

Human rabies is an invariably fatal disease once it manifests clinically. The disease, however, is preventable if medical practitioners and potential victims are adequately educated, and if pre-exposure vaccination is used judiciously. The disease has a worldwide distribution and travellers to many areas are at risk. The authors provide information for people who may be at risk through travel, explain how the disease is diagnosed and describe the use of vaccination before and after exposure.

Humans↗
PubMed1989

Epidermal growth factor and transforming growth factor alpha bind differently to the epidermal growth factor receptor.

Epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) compete with each other for binding to the EGF receptor. These two growth factors have similar actions, but there are distinguishable differences in their biological activities. It has never been clear how this one receptor can mediate different responses. A monoclonal antibody to the EGF receptor (13A9) has been identified which has only small effects on the binding of EGF to the EGF receptor, but which has very large effects on the binding of TGF alpha to the EGF receptor; 5 micrograms/mL antibody has been shown to totally block 0.87 microM TGF alpha from binding to purified EGF receptor and to lower both the high- and low-affinity binding constants of TGF alpha binding to EGF receptor on A431 cells by about 10-fold. The 13A9 antibody causes a 2.5-fold stimulation of the tyrosine kinase activity of partially purified EGF receptor, compared to a 4.0-fold stimulation of the tyrosine kinase activity by EGF under the same conditions. The data suggest either that the antibody stabilizes a conformation of the EGF receptor which is not favorable for TGF alpha binding or that it blocks a part of the surface of the receptor which is necessary for TGF alpha binding but not EGF binding.

Animals↗