Biomedical subjects

J R Clarke

Publications and source records attributed to J R Clarke.

At least 19 recordsLinked to original sources

PubMed1992

Bronchial responsiveness and lung function in infants with lower respiratory tract illness over the first six months of life.

The aim of this study was to determine whether increased bronchial responsiveness to histamine is associated with lower respiratory tract illness (one or more episodes of wheeze or cough, or both) in infancy. Fifty four normal newborn infants who had at least one atopic parent were recruited. At a median age of 6.5 months, 45 infants, 23 with a history of lower respiratory tract illness, and 22 without, underwent pulmonary function testing during a symptom free period. The maximum flow at functional residual capacity (VmaxFRC) was calculated from partial forced expiratory flow volume curves using the squeeze technique. Bronchial responsiveness to increasing doses of histamine was assessed by determining the provoking concentration which caused a 30% decrease in VmaxFRC (PC30). The length adjusted VmaxFRC was lower for symptomatic infants before the challenge (median 125 ml/s; 95% confidence intervals (CI) 85 to 164 ml/s) compared with control infants (median 215 ml/s; 95% CI 159 to 298 ml/s). There was no significant difference in PC30 between symptomatic infants (median 10.3 g/l; 95% CI 2.8 to 23.8 g/l) and control infants (median 16.5 g/l; 95% CI 2.4 to 27.9 g/l). Bronchial responsiveness to histamine can be shown in most infants early in life and is independent of lower respiratory tract symptoms including wheezing.

Bronchi↗

PubMed1992

A study of neuropathy in HIV infection.

A prospective study of possible aetiological factors for neuropathy associated with HIV infection was performed in 80 patients and 28 homosexual controls. At entry to the study twelve patients (15 per cent) had evidence of a generalized neuropathy not due to any other cause and a further three patients developed symptomatic neuropathy during a mean (SD) follow-up of 20 (7.5) months. All but two of these neuropathies were of the distal symmetrical sensory type. Electrophysiology was consistent with an axonal pathology and nerve biopsy confirmed this as the major pathological change. Warming threshold was the diagnostic test most frequently abnormal, sometimes in the absence of other electrophysiological abnormalities. No association was seen with opportunistic infection (cytomegalovirus, herpes simplex, Pneumocystis pneumonia, toxoplasmosis, Cryptococcus infection or tuberculosis). HIV proviral DNA could not be detected in paraffin sections of peripheral nerve in six patients with neuropathy. The presence of the neuropathy did not show significant correlation with depression of the number of CD4+ T cells in the blood, impaired T cell function tests, or IgG, IgM, or IgA levels. Immune complexes containing C1q, but not those containing IgG, IgM, IgA or C3c, were significantly more common among neuropathic patients (p = 0.01).

AIDS-Related Opportunistic Infections↗

PubMed1992

Postgraduate prosthetic training within the community dental service.

There is a need for clinical prosthetics training for community dentists. This was apparent when a postgraduate course, which dealt with prosthetic care of elderly people, was organised for dentists working in the community dental service. Over 100 community dentists applied for 40 places. At the outset they were asked to complete a questionnaire which addressed their professional career together with their current prosthetic experience. The majority of participants were employed at dental officer level; 18 per cent were at senior dental officer level. Many of the dentists worked in districts where one or more community dentists provided all the prosthetic treatment within the community dental service. The majority of districts receive their prosthetic patients as a result of referrals from a variety of sources. Only eight dentists saw the majority of their patients at domiciliary visits; many did not see any patients in this manner. The course participants considered that their greatest clinical weakness in prosthetic skills was in the production of copy dentures and in denture design. Many of the dentists who attended the course did not provide a prosthetic service but most of them said that they anticipated that the necessity for this would increase in the future.

Adult↗

PubMed1992

The uptake and completion of dental treatment using a mobile clinic in central Birmingham, UK.

The provision of a mobile dental service at a primary school in a socially deprived, multi-ethnic area markedly increased the uptake and completion of treatment after a school dental inspection. Eighty one per cent of children who were offered treatment in the mobile clinic accepted it and 91 per cent of these completed it. In the previous year, when care was offered at a health centre within half a mile of the school, the corresponding figure was 43 and 4 per cent. Over half the children seen in the mobile clinic had not previously visited a dentist.

Appointments and Schedules↗

PubMed1991

Polyamine biosynthesis in cells infected with different clinical isolates of human cytomegalovirus.

Previous work in this laboratory showed that polyamine biosynthesis was stimulated in fibroblasts following infection with the AD169 strain of human cytomegalovirus (HCMV) or with murine cytomegalovirus (MCMV) (Tyms et al: Biophysics Research Communications 86:312-318, 1979; Advances in Polyamine Research 4:507-517, 1983). Here we compare the affect of AD169 on polyamine production in infected fibroblasts with that of the unusual Colburn strain of HCMV. The Colburn virus is unusual in that it was isolated from a 7 year old boy with encephalitis and molecular studies indicated the virus was simian like (Huang et al: Journal of Virology 26:718-723, 1978). As a consequence of CMV infection a two to ten fold increase in the spermine content of fibroblast cells is observed. Radiolabel transfer experiments show that spermine is synthesized throughout virus infection. Indeed, spermidine and spermine are specifically incorporated into the purified virions of the AD169 and Colburn strains of HCMV. Furthermore, polyamine biosynthesis is stimulated in fibroblast cells infected with a number of low passage clinical isolates of HCMV. Inhibition of polyamine biosynthesis in HCMV infection may provide a specific and novel target for antiviral chemotherapy.

Cell Line↗

PubMed1991

Effect of HIV-1 and cytomegalovirus in bronchoalveolar lavage cells on the transfer factor for lung carbon monoxide in AIDS patients.

Abnormalities in pulmonary function tests have been observed in AIDS patients with pulmonary disease. In this study, the polymerase chain reaction (PCR) was used to determine if the reductions in transfer factor for lung carbon monoxide (TLCO) were due to the presence of HIV-1 or cytomegalovirus (CMV). HIV-1 was detected in cells from bronchoalveolar lavage (BAL) in 35 out of 60 (58%) of patients. The detection of HIV-1 had no significant effect on pulmonary function. CMV was detected in the BAL of 58% of patients in this study but CMV was the sole viral pathogen in the lung of only two out of 60 (3.3%) individuals. A significant reduction in TLCO was observed in individuals with PCP where CMV was also detected in the BAL. This study shows that reduction in TLCO in HIV-seropositive patients is not due to the presence of HIV-1 or CMV alone in BAL cells.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Recovery of the human immunodeficiency virus from fibreoptic bronchoscopes.

Ten bronchoscopes that had been used on patients with the acquired immunodeficiency syndrome were sampled to determine the nature and extent of microbial contamination. Samples were taken by irrigating the suction biopsy channel with modified viral transport medium and by swabbing the insertion tube. Sampling was repeated after they had been cleaned in detergent and after two minutes' disinfection in 2% alkaline glutaraldehyde. Before being cleaned the seven bronchoscopes tested by polymerase chain reaction were contaminated with the human immunodeficiency virus, though infectivity and antigen assays gave negative results. Other organisms identified were hepatitis B virus (1), commensal bacteria (9), and Pneumocystis carinii (4). Mean bacterial contamination was 2.27 log colony forming organisms per millilitre. Cleaning the bronchoscope before disinfection removed all detectable contaminants with a reduction in bacterial growth of up to 8 log colony forming units/ml.

Bronchoscopes↗

PubMed1991

Acute pain over the appendix. A model of the surgical decision.

The decision to do an appendectomy for a patient with right lower abdominal pain has been analysed. We have described a simple decision tree model of the tradeoffs. The three critical variables can be measured quantitatively. The probability of appendicitis has been predicted. The probability that an inflamed appendix will perforate during observation can be estimated. It can be projected that the rate of perforation is increased in the very young and old. Therefore, the minimal threshold probability of appendicitis justifying an appendectomy is lower at the extremes of age. The decision must consider not only the probabilities of outcomes, but their utilities as well. The utility of appendectomy is discussed. Experience measuring the personal utilities of appendectomy in a group of surgeons using a standard gamble technique is presented. The variation in utilities was greater than expected. The perceived ratio of the magnitude of the increased risk of an avoidable perforation compared to that of an unnecessary operation ranged from over 30:1 to less than 1:3, with a median of about 3.5:1. The ratio predicted from mortality and morbidity rates had a median range from 20:1 to 2:1. Other factors may be influencing the utility assessments. The individual's utility for appendectomy could be shown to have a large influence on the decision to operate or observe.

Abdomen, Acute↗

PubMed1990

Use of the polymerase chain reaction to detect DNA sequences specific to pathogenic treponemes in cerebrospinal fluid.

The polymerase chain reaction was used to detect Treponema pallidum in specimens of cerebrospinal fluid (CSF), as a means of diagnosing syphilis. Segments of the TmpA and 4D genes were amplified to provide an estimated threshold sensitivity of approximately 65 organisms in 0.5 ml. A spectrum of pathogens known to cause meningitis, and several non-pathogenic treponemes were unreactive. Treponema pertenue, and only one of 30 control specimens of CSF were positive. In contrast, 10 of 19 CSFs from patients being evaluated for latent or tertiary syphilis were positive, as were 7 of 28 specimens from HIV-positive patients.

Animals↗

PubMed1990

Identification of human appendicitis by in vitro nuclear magnetic resonance.

The spin-lattice relaxation time, T1 as determined by nuclear magnetic resonance techniques, correlates positively with tissue water content. The latter relationship has been observed in rabbits with experimentally induced appendicitis whose inflamed appendiceal tissues had significantly higher T1's and water contents than tissue from normal controls. The present experiment studied these relationships in humans. Tissue water content and T1 were measured on appendiceal tissue from 10 patients with documented appendicitis and from 6 controls without the disease. All T1's were determined within 30-60 min of removal of the appendix at operation. The mean in vitro T1 of appendiceal tissue from patients with appendicitis was significantly higher than that of controls (527 +/- 15 msec versus 430 +/- 17 msec, mean +/- SEM, P less than 0.002). In addition, a strong positive correlation was noted between T1 and tissue water content (r = 0.70, P less than 0.01). Based on these findings, the use of in vivo magnetic resonance imaging techniques to detect human appendicitis noninvasively warrants investigation.

Adolescent↗

PubMed1990

Detection of HIV-1 in human lung macrophages using the polymerase chain reaction.

We have used the polymerase chain reaction to investigate HIV-1 infection of lung macrophages from 44 AIDS patients with pneumonia. Proviral HIV-1 DNA was detected in the lung macrophages of 47% (21 of 44) of patients tested; 32% (seven of 21) of the patients had Pneumocystis carinii pneumonia (PCP), and 56% (11 of 21) had pneumonia caused by other aetiological agents. Matched peripheral blood specimens were obtained from 22 patients in this study, and HIV-1-specific DNA was detected in 100% (22 out of 22) of non-adherent white cell preparations tested. HIV was detected in blood monocytes of 11 out of 22 patients (50%), and a virus signal was also found in the lung macrophages of eight of these patients. Our results indicate that PCP does not predispose lung macrophages to HIV-1, nor does HIV-1 infection of lung macrophages increase the probability of contracting PCP.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Detection of treponemal DNA in the CSF of patients with syphilis and HIV infection using the polymerase chain reaction.

The polymerase chain reaction (PCR) was used to detect Treponema pallidum DNA in the cerebrospinal fluid (CSF) of patients with and without syphilis. The CSF from 10 of 19 patients with positive serological tests for syphilis who were being investigated for late syphilis were treponemal DNA-positive. In contrast, the CSF from only one of 30 patients with no known history of syphilis was DNA-positive. CSF from 28 HIV-positive patients was also tested. Fourteen of these patients had central nervous system (CNS) disease and seven were DNA-positive, whereas none of the 14 without CNS disease were DNA-positive. Five of the seven DNA-positive patients had a history of syphilis. Such a history in an HIV-positive patient who had CNS disease was predictive of finding treponemal DNA in the CSF. The PCR had a sensitivity of 47% and a specificity of 93% for detecting a known history of syphilis and is a potentially useful tool in treponemal diagnosis.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Avoidance of used endometrial sites by blastocysts of the bank vole, Clethrionomys glareolus.

In bank voles blastocysts arising from mating immediately after parturition do not implant in used zones of the preceding pregnancy but in the regions between them. However, if mating is postponed until 12 or more days after parturition blastocysts do implant in used zones of the previous pregnancy. Implantations also occur at zones used two pregnancies previously. It seems likely that the absence of implantations at recently used zones of the uterus is determined by the uterus rather than blastocysts.

Animals↗

PubMed1989

Contamination of endoscopes used in AIDS patients.

Contamination of twenty endoscopes used in patients with AIDS was assessed. The suction-biopsy, air, and water channels and the insertion tube were sampled after use, after washing in detergent, and after disinfection for 2 min in 2% alkaline glutaraldehyde. The polymerase chain reaction with Southern blotting, cell cultures, and antigen immunoassay were used to detect human immunodeficiency virus (HIV). Samples were also examined for cytomegalovirus, adenoviruses, enteroviruses, herpes simplex virus, myxoviruses, hepatitis B surface antigen, fungi, and bacteria. Seven of twenty unwashed endoscopes were contaminated by HIV. Commensal bacteria were found in all endoscopes, Candida albicans in six, Staphylococcus aureus in five, and Pseudomonas aeruginosa in five. Washing alone removed all detectable organisms from 66 of 68 contaminated sites; Neisseria spp were recovered from two air channels after washing but not after disinfection. Washing achieved a mean reduction of 4.93 (95% confidence interval 3.69-6.17) colony forming units per ml.

Acquired Immunodeficiency Syndrome↗

PubMed1989

The type-specific epitopes of the Epstein-Barr virus nuclear antigen 2 are near the carboxy terminus of the protein.

The Epstein-Barr virus nuclear antigen 2 (EBNA 2) shows serotype variation and two serologically distinct groups of viruses have been identified. These correspond to the two hybridization groups of viruses (A and B) that are distinguished by a highly substituted nucleic acid sequence in the middle of the open reading frame of the EBNA 2 gene. An epitope survey of the EBNA 2-coding region was carried out using a new prokaryotic expression vector tailored to express DNA fragments from the M13 sequencing libraries of the B95-8 (type A) and Jijoye (type B) prototype virus strains. Short overlapping stretches of EBNA 2 sequence were expressed as fusion proteins and used in Western blotting with human sera that contained serotype-specific antibodies. The type A-specific epitope was located between residues 378 and 435 of the B95-8 EBNA 2 polypeptide and the type B-specific epitope mapped between residues 390 and 454, at the carboxy terminus of the Jijoye polypeptide chain. All of the type-specific anti-EBNA 2 sera tested reacted with fusion proteins containing one or other of these epitopes. Despite the direct correlation between the hybridization and serological phenotypes, the type-specific epitopes appear to lie in the relatively conserved carboxy-terminal region of EBNA 2. There was no indication that the residues of the non-homologous region contributed to the formation of antibody-combining sites.

Amino Acid Sequence↗

PubMed1989

Ovarian interstitial tissue of the wood mouse, Apodemus sylvaticus.

The ovary of the wood mouse contains an unusually large amount of interstitial tissue which appears to develop from undifferentiated cells of the ovarian stroma and also by transformation of theca or granulosa cells of atretic follicles. The cells are characterized by the presence of smooth endoplasmic reticulum, rounded mitochondria with tubular cristae, and abundant, large (1.5 micron diameter) lipid droplets containing cholesterol and its esters. 3 beta-Hydroxysteroid dehydrogenase activity occurs in the interstitial cells. Their ultrastructural characteristics suggest that the cells are not very active, but their abundance and the considerable amount of steroid hormone precursor they contain may compensate for low secretory activity and they may be an important and (from a developmental viewpoint) early source of steroid hormone.

3-Hydroxysteroid Dehydrogenases↗

PubMed1988

Artificial intelligence: a computerized decision aid for trauma.

A computerized decision support system has been developed to advise ATLS-trained surgeons on the initial definitive management of patients with penetrating injuries of the abdomen immediately following resuscitation and stabilization. The program was developed as an "expert system," using the techniques of artificial intelligence. It is able to suggest: the need for further examination; additional tests; diagnoses; and treatments. In this study, the advice offered by the expert system was compared to that of physicians-in-training. Five actual patient care situations were presented to the system and to 13 medical students and surgical residents: four MS-III, three PGY-I, three PGY-III, and three PGY-V. The suggestions of each of the 13 trainees, the advice of the expert system, and the actual management were blinded. Five surgeons versed in trauma and otherwise not involved in the project judged whether each of the 15 purported management plans was acceptable and ranked them in order of preference. Only the actual care and the advice from the system were judged acceptable for all five problems. The rankings of the expert system were better than those of any individual trainee. The differences were statistically significant for two of the three chief residents, five of nine residents overall, and all four students. This preliminary validation of a prototype expert system is encouraging for the prospect of a computerized decision support system that can help surgeons make initial definitive management plans for patients with major trauma.

Abdominal Injuries↗

PubMed1988

Treatment of senile entropion with botulinum toxin.

Botulinum toxin was used to treat senile entropion in 12 patients by injection into the preseptal orbicularis muscle of the lower lids. It produced relief of symptoms in 10 patients but this was transient, lasting for an average of 14.8 weeks before orbicularis function returned. The technique is simple and easy to perform, and may be useful in selected patients, but surgery offers a more permanent result.

Acetylcholine↗