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Biomedical subjects

J Roberts

Publications and source records attributed to J Roberts.

At least 523 records · Page 29Linked to original sources
PubMed1985

Specialized nucleoprotein structures at the origin of replication of bacteriophage lambda: complexes with lambda O protein and with lambda O, lambda P, and Escherichia coli DnaB proteins.

The O protein of bacteriophage lambda is required for initiation of DNA replication at the lambda replicative origin designated ori lambda. The binding sites for O protein are four direct repeats, each of which is an inverted repeat. By means of electron microscopy, we have found that phage lambda O protein utilizes these multiple binding sites to form a specific nucleoprotein structure in which the origin DNA is inferred to be folded or wound. The phage lambda O and P proteins and host DnaB protein interact at ori lambda to generate a larger structure than that formed by O protein alone; P and DnaB proteins fail to form any observable complex when O protein is excluded from the reaction mixture. We conclude that the specialized nucleoprotein structure formed by phage lambda O protein and ori lambda provides for localized initiation of DNA replication by serving as the foundation for the assembly of the initial priming structure. Specialized nucleoprotein structures may be a general means to confer exceptional accuracy on DNA transactions requiring extraordinary precision.

Bacterial Proteins↗
PubMed1985

Effect of gold thioglucose-induced obesity on adipose tissue weight and cellularity in male and female mice suckled in large and small litters: investigations into sex differences and site differences.

1. Over- or undernutrition of newborn mice was caused by suckling in litters consisting initially of four or eighteen pups. After weaning, mice were fed ad lib. At 13 weeks some mice received gold thioglucose (GTG, 600 mg/kg, intraperitoneally) to induce hyperphagia, and all were killed at 39 weeks. 2. Mice suckled in small litters were heavier, with more body fat and protein. GTG treatment induced rapid weight gain and treated mice from large litters were heavier than untreated mice from small litters. However, the effect of litter size was not totally removed since GTG-treated small-litter mice were heavier than GTG-treated large-litter mice and had more fat, although body protein was not different. 3. Fat distribution between the depots was related to total body fatness and not to the treatment. 4. In male mice, preweaning undernutrition resulted in smaller fat depots containing smaller cells. GTG treatment of large-litter mice restored both to the levels found in small-litter mice: the depots of the latter mice were not significantly different after treatment. 5. In female mice, preweaning undernutrition resulted not only in smaller depots and cells but also fewer cells in all depots except mesenteric. GTG-treatment caused larger depots and cells in all mice with no difference in cell size whether mice were from large or small litters. The number of cells in the perirenal and mesenteric depots was greater in GTG-treated mice and was the same whether mice were from large or small litters. 6. We conclude that the level of preweaning nutrition does not affect the ability of adipose tissue to develop subsequently through hypertrophy or hyperplasia of the adipocytes or both, given a sufficient energy surplus consisting of normal pelleted feed, low in lipid.

Adipose Tissue↗
PubMed1985

The risk of child abuse among mothers who attempt suicide.

The association between parental attempted suicide and child abuse was investigated in 114 mothers with children aged five years and under, referred to a general hospital following suicide attempts. The risk was greatly increased in the attempted suicide mothers, compared with both similar mothers at risk for depression and general population control mothers; well-documented risk of child abuse was identified in 29.8% of those who attempted suicide. No major differences were found between the attempted suicide mothers whose children were at risk and those whose children were not at risk. During the general hospital assessment of mothers with young children who attempt suicide, careful enquiry concerning the relationship with the children is essential.

Adult↗
PubMed1985

Fatal anaphylactic reaction to oral penicillin: report of case.

A report of a fatal anaphylactic reaction to oral penicillin is presented and the unusual set of circumstances leading to its fatal outcome is reviewed. The initial signs and symptoms are analyzed and the use of the proper and immediate treatment is advised.

Administration, Oral↗
PubMed1984

Effects of age on the adrenergic cardiac neuroeffector junction.

Although it is clear that adrenergic nervous system control of cardiac function decreases with age and that the effector organ fails to adjust to this decreased control, it is not completely evident which of the many mechanisms operant at the adrenergic-cardiac neuroeffector junction contribute to this state. Prejunctionally, it appears that norepinephrine content decreases with age and that adrenergic axonal degeneration occurs. Also, evidence is available to suggest that modulation by prejunctional alpha adrenergic receptors of norepinephrine release is altered with increasing age, as is neuronal uptake of norepinephrine. Postjunctionally, it appears that beta-adrenergic receptor sensitivity to agonists undergoes age-related alterations, and possibly post receptor mechanisms involved in receptor-response coupling. Other mechanisms, such as those involved in transmitter uptake into extraneuronal sites, adrenergic neuronal responsiveness to stimulation, transmitter release and turnover, calcium and prejunctional receptor modulation of transmitter release, postjunctional receptor development of supersensitivity or subsensitivity, need further elucidation in order to have an understanding of the factors that contribute to the breakdown of homeostatic mechanisms that regulate the heart.

Aging↗
PubMed1984

Is there a link between cot death and child abuse?

Forty five babies delivered in Oxford obstetric units who subsequently died unexpectedly in infancy were compared with 134 controls matched for maternal age, social class, parity, and year of birth to see whether five factors identified in an earlier study as predictive of subsequent child abuse would also predict the sudden infant death syndrome. Epidemiological findings had suggested certain similarities between the two events. In contrast with babies who were abused, four of the five factors did not distinguish between babies who died suddenly and unexpectedly and their controls, but there was a slight increase in the proportion of mothers of babies who died suddenly and unexpectedly for whom nursing staff thought that support and advice on feeding the baby were needed. Factors predictive of child abuse did not predict sudden infant death in this study.

Affective Symptoms↗
PubMed1984

Kinetic studies of Ca2+ release from sarcoplasmic reticulum of normal and malignant hyperthermia susceptible pig muscles.

The time-course of Ca2+ release from sarcoplasmic reticulum isolated from muscles of normal pigs and those of pigs susceptible to malignant hyperthermia were investigated using stopped-flow spectrophotometry and arsenazo III as a Ca2+ indicator. Several methods were used to trigger Ca2+ release: (a) addition of halothane (e.g., 0.2 mM); (b) an increase of extravesicular Ca2+ concentration ([Ca2+0]); (c) a combination of (a) and (b), and (d) replacement of ions (potassium gluconate with choline chloride) to produce membrane depolarization. The initial rates of Ca2+ release induced by either halothane or Ca2+ alone, or both, are at least 70% higher in malignant hyperthermic sarcoplasmic reticulum than in normal. The amount of Ca2+ released by halothane at low [Ca2+0] in malignant hyperthermic sarcoplasmic reticulum is about twice as large as in normal sarcoplasmic reticulum. Membrane depolarization led to biphasic Ca2+ release in both malignant hyperthermic and normal sarcoplasmic reticulum, the rate constant of the rapid phase of Ca2+ release induced by membrane depolarization being significantly higher in malignant hyperthermic sarcoplasmic reticulum (k = 83 s-1) than in normal (k = 37 s-1). Thus, all types of Ca2+ release investigated (a, b, c and d) have higher rates in malignant hyperthermic sarcoplasmic reticulum than normal sarcoplasmic reticulum. These results suggest that the putative Ca2+ release channels located in the sarcoplasmic reticulum are altered in malignant hyperthermic sarcoplasmic reticulum.

Animals↗
PubMed1984

Corticotropin-releasing factor (CRF) stimulates locomotor activity in intact and hypophysectomized newts (Amphibia).

Locomotor activity of rough-skinned newts (Taricha granulosa) was significantly higher in intact and hypophysectomized males injected intracranially with 100 ng CRF (ovine corticotropin-releasing factor) than in those injected with 10 ng CRF or saline. In addition, an injection of corticosterone or dexamethasone failed to stimulate newt locomotor activity. These results provide evidence that CRF can act independently of pituitary hormones to stimulate locomotor activity in a nonmammalian vertebrate.

Animals↗
PubMed1984

Appendicitis masking as recurrent squamous cell carcinoma of the cervix.

The diagnosis of pelvic recurrent squamous cell carcinoma of the cervix is made on the basis of clinical assessment and radiologic confirmation. Occasionally the diagnosis is confused with sequelae of radiation therapy. The authors describe the symptoms and signs of appendicitis mimicking recurrent squamous cell carcinoma in a 43-year-old female. A 10-year search of the literature has failed to detect another case report or review. The authors believe that, if there is ever any doubt as to the diagnosis of pelvic recurrent squamous cell cancer, exploratory laparotomy and biopsies are warranted for confirmation.

Adult↗
PubMed1984

Continuous axillary block through an indwelling Teflon catheter.

Continuous regional anesthesia through a catheter placed in the axillary sheath has been an effective method of brachial plexus neural blockade. This article confirms this observation and demonstrates that continuous axillary block is useful in replantation surgery to provide anesthesia and analgesia in addition to sympathetic blockade for up to 7 days after operation. This anesthetic technique may allow extensive revascularization or replantation procedures to be performed for patients who could not safely tolerate prolonged application of general anesthesia.

Arm Injuries↗
PubMed1984

Comparison of the psychosocial effects of epilepsy and narcolepsy/cataplexy: a controlled study.

A questionnaire survey compared the psychosocial effects of epilepsy in 60 patients without major organic pathology (selected cases with temporal lobe epilepsy or primary generalized epilepsy) with those of matched (duration of illness, sex) patients with narcolepsy/cataplexy and with those of age- and sex-matched controls. Comparing epileptic patients with controls, we confirmed the well-documented marked deleterious effects of epilepsy upon work, education, occupational and household accidents, recreation, personality, interpersonal relations, and other parameters. Comparisons of epileptic and narcoleptic patients, however, showed that, in general, persons with narcolepsy are even more psychosocially impaired. The narcoleptic patients showed greater frequencies of disease-attributed reduced performance at work, poorer driving records, higher accident rates from smoking, greater problems in planning recreation, and other significant differences. Rather dissimilar profiles of psychosocial impairment were found to characterize the two conditions, and these were largely understandable as a function of their symptoms. The only areas in which epileptic patients showed greater problems than those with narcolepsy were in educational achievement and in ability to maintain a driving license. Most of the intergroup differences remained significant even for smaller groups matched also for age. The somewhat greater psychosocial impact of narcolepsy appears to be due to the continuous excessive daytime sleepiness that persists between the diagnostic attacks, whereas persons with epilepsy are relatively alert between seizures.

Accidents↗
PubMed1984

Micro-organisms in gastroenteritis.

We present bacteriological and virological findings together with salient clinical features from a prospective study of 447 children aged under 2 years admitted to hospital with infectious gastroenteritis. Putative pathogenic micro-organisms were identified in the stools of 75% of these children. Eight identifiably distinct groups of viruses, found on electron microscopy and tissue culture were present in 67% of patients--rotavirus was detected most frequently. Pathogenic bacteria (salmonellas, shigellas, Escherichia coli, and Campylobacter jejuni--but excluding Clostridium difficile) were found in 16% only. Altogether 4 X 9% of 390 patients had gastroenteritis associated with Cl difficile toxin. The mean duration of diarrhoea was shortest in patients with identifiable virus, with rotavirus having a mean of 5 X 01 days, and was longest in patients with pathogenic bacteria in the stools (11 X 14 days). The finding of more than one type of virus did not seem to be associated with a significantly increased duration of diarrhoea. There are few clinical features which can be associated specifically with any particular micro-organism or groups of these. Multiple organism isolation was common, but the severity of the illness in those patients with at least two types of organism was not greater. Certain viruses, including the norwalk-like virus, known to be associated with outbreaks of gastroenteritis were found as frequently in a group of patients who did not have diarrhoea studied for comparison. Virus was still detectable in the stools of up to 40% of asymptomatic children on the day of discharge.

Adenoviruses, Human↗
PubMed1984

Effect of age on adrenergic neuronal uptake in rat heart.

Cardiovascular responsiveness to sympathetic influences is reduced with increasing age. This reduced responsiveness may reflect alterations in effector mechanisms or in neurohumoral transmission processes. We investigated the effect of age on the cardiac adrenergic neuronal uptake mechanism in the Fischer 344 rat by measuring the cocaine-induced potentiation of norepinephrine (NE) positive chronotropic responses. Hearts from male rats (6, 12 and 24 months old) were perfused according to a modified method of Langendorff. For each heart, chronotropic responses to increasing doses of NE were obtained. After this, hearts were perfused with 1 microM cocaine to block the neuronal uptake of NE. A second series of NE doses were administered and heart rate (HR) responses measured. Under control perfusion conditions, HR responses to NE decreased with increasing age. In the presence of cocaine, HR responses to NE were significantly augmented in the 12 and 24 months rat hearts, but not in the 6 months rat hearts. However, the cocaine-potentiated responses to NE at 12 and 24 months did not exceed responses to NE alone at 6 months. In a separate series of experiments, HR responses to isoproterenol were not modified by cocaine at any age. These results indicate that activity of neuronal uptake pump is greater in the 12 and 24 months rats than in the 6 months rats. This increased uptake activity may account at least in part for the reduced responsiveness of older hearts to NE.

Aging↗
PubMed1983

Entry to general practice training.

Since 1979 general practitioner trainees in the North West Region of England have been assessed on knowledge and ability by several tests, including the multiple choice test. Trainers in the region require a score in the MCQ of 45% before taking a trainee into the practice. More British graduates have achieved this score than overseas graduates. The difference was statistically significant. Only applicants who show adequate factual recall should be appointed as trainees.

Education, Medical, Graduate↗