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Biomedical subjects

R Carter

Publications and source records attributed to R Carter.

At least 235 records · Page 13Linked to original sources
PubMed1990

Variation of breath sound and airway caliber induced by histamine challenge.

Inspiratory breath sounds were recorded from the chest wall during histamine challenge in five subjects with mild asthma (baseline FEV1 greater than 60% of predicted normal). The median frequency of the power spectrum of the breath sounds was found to correlate with the percentage change in FEV1 induced by histamine and with FEF50. The analysis suggests that for a decrease in FEV1 of 20%, the median frequency of breath sound would increase by 80 Hz. Variation in airway caliber produced a consistent alteration in the distribution of energy in inspiratory breath sound in the absence of wheeze. Spectral analysis of breath sound may be a useful addition to conventional spirometry in identifying changes in airway diameter.

Adult↗
PubMed1990

Genetic complexity of Plasmodium vivax parasites in individual human infections analyzed with monoclonal antibodies against variant epitopes on a single parasite protein.

Monoclonal antibodies against variant epitopes of a highly polymorphic protein (PV200) in schizonts of Plasmodium vivax have been used to analyze the variety of genetically distinct populations of parasites present in the peripheral blood of individual P. vivax infections in Sri Lanka. In 9 out of 10 isolates of freshly drawn P. vivax infected blood from different individuals, parasites of only 1 PV200 serotype was found within each individual infection, even though parasites were serotypically distinct between individuals. In 1 isolate parasite population, 3 distinct PV200 serotypes were identified. Thus, most P. vivax infections appeared to consist of a single genetically homogeneous population of parasites within the detection limits of the technique. The prevalence of P. vivax infections in an area of malaria transmission in southern Sri Lanka and the densities of oocysts in mosquitoes fed on P. vivax infected individuals indicated that parasite populations would be transmitted many times before encountering parasites of other origins, and that individual populations would tend to reduce to genetic homogeneity during transmission. These expectations are consistent with the high proportion of genetically homogeneous P. vivax isolates observed.

Adult↗
PubMed1990

Use of synthetic peptides in the study of the antibody response to Plasmodium vivax sporozoites.

Synthetic peptides reproducing 4 DRADGQPAG (D4) and a sequential array of DRADGQPAG and DRAAGQPAG repeats (DDAAD) of the Plasmodium vivax circumsporozoite (CS) protein were investigated for their potential use in the detection of P. vivax sporozoite antibodies in human sera. These peptides specifically inhibited the binding of monoclonal antibodies to the P. vivax CS protein in Western blots. However, when D4 and DDAAD peptides were used in an enzyme-linked immunosorbent assay (ELISA) for the detection of human antibodies, more sera bound to the DDAAD (61%) than to the D4 peptide (22%). This binding was specific, and suggested that the DDAAD peptide contained epitopes constituted by the sequential array of DRADGQPAG and DRAAGQPAG repeat variants and absent in the D4 peptide. The ELISA using the DDAAD peptide was applied to the detection of P. vivax CS protein antibodies in a large number of sera from Kataragama, an endemic area in Sri Lanka. The prevalence of these antibodies increased with age, reaching 40% in adults greater than 50 years old. The ELISA employing the DDAAD peptide represents a simple and useful tool for the analysis of the antibody response to P. vivax sporozoites in naturally exposed individuals.

Age Factors↗
PubMed1990

Characteristics of malaria transmission in Kataragama, Sri Lanka: a focus for immuno-epidemiological studies.

Parasitological and entomological parameters of malaria transmission were monitored for 17 months in 3,625 residents in a Plasmodium vivax malaria endemic region in southern Sri Lanka; the study area consisted of 7 contiguous villages where routine national malaria control operations were being conducted. Malaria was monitored in every resident; fever patients were screened and 4 periodical mass blood surveys were conducted. An annual malaria incidence rate of 23.1% was reported during the period: 9.3% was due to P. vivax and 13.8% was due to P. falciparum; there had been a recent epidemic of the latter in this region, whereas the P. falciparum incidence rate in the previous 10 years had been negligible. There was a wide seasonal fluctuation in the malaria incidence, with the peak incidence closely following the monsoon rains. The prevalence of malaria due to both species detected at the 4 mass blood surveys ranged from 0.98% (at low transmission) to 2.35% (at peak transmission periods). Adults and children developed acute clinical manifestations of malaria. Entomological measurements confirmed a low degree of endemicity with estimated inoculation rates of 0.0029 and 0.0109 (infectious bites/man/night) for P. vivax and P. falciparum, respectively. Several anopheline species contributed to the transmission, and the overall man biting rates (MBR) showed a marked seasonal variation. Malaria at Kataragama, typical of endemic areas of Sri Lanka, thus presents characteristics of "unstable" transmission. Malaria was clustered in the population. There was a low clinical tolerance to P. falciparum malaria, to which most had only been at risk, compared to P. vivax, to which most had had a life-long exposure.

Adolescent↗
PubMed1990

High frequency of antibody response to Plasmodium falciparum gametocyte antigens during acute malaria infections in Papua New Guinea highlanders.

Sera from 62 adult Papua New Guinea highlanders with suspected acute malaria were tested by competitive ELISA for the presence of antibodies capable of inhibiting binding of 8 monoclonal antibodies (Mabs) directed against epitopes on gametocytes of Plasmodium falciparum. Between 33% and 72% of the malaria cases were inhibitory, depending on the Mab. There was no difference between the proportion of persons with P. falciparum (asexuals or gametocytes) and P. vivax whose sera inhibited Mab binding, but all 3 categories had a significantly higher proportion of inhibitors than persons who were malaria negative. The amount of gametocyte antibody recognizing epitopes on Pfs 48/45 and Pfs 230 increased with increasing numbers of previous malaria episodes. The proportion of sera from these relatively nonimmune adults which had gamete antibodies was similar to the proportion seen in sera from a highly endemic area, suggesting that antibody responses to these epitopes are a part of the initial response observed after a limited number of malaria episodes.

Acute Disease↗
PubMed1989

Restricted or absent immune responses in human populations to Plasmodium falciparum gamete antigens that are targets of malaria transmission-blocking antibodies.

We have studied the antibodies to sexual stage antigens of Plasmodium falciparum in human sera from Papua New Guinea where intense transmission of P. falciparum occurs as well as the less prevalent P. malariae and P. vivax. In extracts of gametes of P. falciparum we have studied the reactivity of serum antibodies with antigens labeled with 125I on the surface of the gametes as well as intracellular gamete antigens. A prominent 27-kD sexual stage-specific intracellular protein was recognized more or less in proportion to the general antibody response to gamete proteins. The response to the gamete surface proteins, however, was quite unrepresentative of the general antibody response to the intracellular gamete proteins. No antibodies were detected against Pfs25, a 21-kD protein expressed on zygotes and ookinetes of P. falciparum and known to be a sensitive target of malaria transmission-blocking antibodies. The antibody response to two other target antigens of transmission-blocking antibodies on the surface of gametes of P. falciparum, a 230- and a 48- and 45-kD protein doublet, was very variable and independent of the response to the internal protein antigens. Several possibilities are discussed that may account for the variable response to these gamete surface antigens in individuals with otherwise good antibody responses to internal sexual stage proteins. Among these is the possibility that there is MHC restriction of the immune response to the gamete surface antigens in the human population. This interpretation accords well with evidence for MHC-restricted immune response to the same P. falciparum gamete surface antigens in studies with H-2 congenic mice (24).

Animals↗
PubMed1989

Plasmodium falciparum: an abundant stage-specific protein expressed during early gametocyte development.

A stage-specific protein has been identified in gametocytes of Plasmodium falciparum. The protein is represented on two-dimensional electrophoresis by peptides of two apparent Mr of 27,000 and 25,000, each of which has at least four different isoelectric points between pH 6.0 and 5.0. The protein is designated Pfg 27/25 (P. falciparum gametocyte-specific antigen of 27 and 25 kDa). By indirect immunofluorescence with a monoclonal antibody 1H12 specific for Pfg 27/25, this protein is present in gametocytes within 30 to 40 hr after invasion of a red blood cell by a merozoite and is present throughout subsequent maturation of the gametocyte; Pfg 27/25 is not detectable on the surface of extracellular gametes by immunofluorescence with Mab 1H12. Pfg 27/25 is absent from asexual stages of P. falciparum at any stage in their development. Pfg 27/25 is an abundant protein in gametocytes and represents between 5 and 10% of total protein of these stages. Pfg 27/25 is also a major immunogen in man during P. falciparum infection. Antibodies to this protein were readily detected in human sera from an area of holoendemic P. falciparum and also from an individual following a primary attack of P. falciparum.

Animals↗
PubMed1989

Outcome of TIAs of unknown aetiology following non-invasive evaluation.

A proportion of patients with apparently classical transient ischaemic attacks (TIA), will have no cause for their symptoms discovered when investigated. We have reviewed 74 patients with TIA and a further 28 with amaurosis fugax whose symptoms remained unexplained following non-invasive carotid evaluation using pulsed Doppler imaging with spectrum analysis. After a mean follow-up of 31.7 months, 48.6% of TIA patients were symptom free, 36.5% had experienced recurrent symptoms and 8.1% had suffered a stroke. Among the patients with amaurosis fugax the equivalent figures were 32.1% symptom free, 42.7% recurrent symptoms, and 10.7% stroke. These figures suggest that unexplained TIAs do not necessarily have a benign prognosis and more extensive or repeated investigation of these patients is warranted.

Adult↗
PubMed1989

Long term haemodynamic, pulmonary function and symptomatic effects of pirbuterol in COPD.

Haemodynamic studies at rest and during exercise together with radionuclide ventriculography, pulmonary function and clinical well-being assessment were evaluated in ten patients with COPD and secondary pulmonary hypertension (mean PAP 25 mm Hg), before and after 6 months therapy with pirbuterol 20 mg thrice daily. Despite the continued pharmacological action of pirbuterol on the heart and systemic circulation during peak pirbuterol levels at 6 months, no significant effect on the pulmonary circulation was observed. Seven patients reported an improvement in the level of fatigue, the partial pressure of carbon dioxide fell significantly (6.5 +/- 0.9 to 6.1 +/- 0.9 kPa: P less than 0.01) and there was a slight bronchodilator effect [forced expiratory volume in 1s (FEV1) 0.60 +/- 0.18 to 0.71 +/- 0.2 1s-1: P less than 0.02] after 6 months. The drug was generally well tolerated but three patients with pre-existing biliary tract disease developed obstructive jaundice.

Aged↗
PubMed1989

Serum lipid response to dietary cholesterol in subjects fed a low-fat, high-fiber diet.

To determine whether hyperresponse to dietary cholesterol occurs in individuals consuming a low-fat diet, a study was performed on 58 subjects whose plasma cholesterol had changed by greater than or equal to 5% when intakes of two and seven eggs per week were compared in a previous study. Here, the effect of eating nine, zero, and nine eggs per week was studied over 3 consecutive months. Plasma total, LDL, and HDL cholesterol did not differ significantly. There was no correlation between individuals' lipoprotein changes in this and the previous study. Consistent hyperresponse to moderate cholesterol intake is not apparent in people eating a low-fat, high-fiber diet. Reduction in dietary cholesterol below 400 mg/d produces no further substantial cholesterol lowering.

Adult↗
PubMed1989

The effects of secondary transport on critically ill patients.

This study examined the effect of secondary transport on critically ill patients and the effectiveness of a regionally based intensive care service. Four hundred and ninety-five patients were studied retrospectively over a 2-year period. Eighty-two were transferred from peripheral hospitals in a mobile intensive care unit while the remaining 413 were admitted directly to the intensive therapy unit at the Western Infirmary, Glasgow. The severity of illness in both groups was assessed using the APACHE II scoring system. The transferred group were scored before and after the journey, while the directly admitted group were scored only on admission. The results show that the transferred patients exhibited a consistent cardiorespiratory response to transport irrespective of their severity of illness, and that the mortality in both groups of patients in the intensive therapy unit was not significantly different. The results also suggest that in the transferred group, the outcome is not only dependent on the severity of illness but also on other factors, such as the hospital from which the patient was referred and the duration of the pretransfer admission.

Adolescent↗
PubMed1989

Obstructive airways disease in non-smoking subjects with pigeon fanciers' lung.

The aim of the study was to assess the degree of airways involvement in non-smoking subjects with extrinsic allergic alveolitis resulting from pigeon-derived antigens. Two hundred and eight pigeon fanciers completed a questionnaire of symptoms, performed spirometry on a Vitalograph Compact spirometer and had IgG antibody to pigeon gamma-globulin measured. Eighty fanciers had the acute form of pigeon fanciers' lung (PFL) and these subjects were less likely to be current smokers (P less than 0.001). Subjects with PFL had a higher prevalence of chronic bronchitis (P less than 0.001), large airways (P = 0.014) and peripheral airways obstruction (P less than 0.001). The prevalence of chronic bronchitis and peripheral airways obstruction increased significantly as the level of antibody to pigeon gamma-globulin rose. Peripheral airways obstruction, as manifest by a reduced FEF25-75%, was the most common abnormality found. Airways disease is an important feature of the acute form of PFL and consists of a hypersecretory disorder in the form of chronic bronchitis and of obstructive airways disease particularly affecting the peripheral airways.

Adolescent↗
PubMed1989

Is the treatment of urgency incontinence a placebo response? Results of a five-year follow-up.

The treatment and symptomatic outcome were reviewed in 50 women who had presented with urgency incontinence as their main symptom 5 years previously. All had idiopathic urgency incontinence and, on the basis of urodynamic investigation, 40 were considered to have detrusor instability and 10 sensory urge incontinence. The results indicate that the natural history of sensory urgency is one of spontaneous resolution; all treatments of detrusor instability (including surgery) produced an unsustained short-term symptomatic response. This pattern of response to therapy may be interpreted as being largely of a placebo nature and this emphasises the need for long-term follow-up in the assessment of new treatment modalities.

Adolescent↗
PubMed1989

Movement of a falciparum malaria protein through the erythrocyte cytoplasm to the erythrocyte membrane is associated with lysis of the erythrocyte and release of gametes.

Erythrocytes containing mature gametocytes of Plasmodium falciparum circulate in the blood until they are ingested by a mosquito, an event that triggers gametogenesis and lysis of the infected erythrocyte. It was previously shown that a parasite protein (Pf155/RESA) accumulates in the erythrocyte cytoplasm next to the parasitophorous vacuolar membrane (S. Uni, A. Masuda, M. J. Stewart, R. Nussenzweig, and M. Aikawa, Am. J. Trop. Med. Hyg., 36:481-488, 1987). Using a monoclonal antibody to Pf155/RESA and rabbit sera to two different repeat peptides of Pf155/RESA, we have studied the location of Pf155/RESA after induction of gametogenesis. Five minutes after triggering gametogenesis, the parasitophorous membrane no longer surrounded the parasite, bringing the parasite membrane in contact with the erythrocyte cytoplasm. Clear spaces appeared throughout the hemoglobin-rich host cytoplasm; Pf155/RESA was now localized in the cytoplasm directly surrounding the spaces. No membrane existed between the spaces and the erythrocyte cytoplasm. The spaces with surrounding Pf155/RESA protein extended to the erythrocyte membrane. After lysis of the erythrocyte membrane (15 min after triggering gametogenesis), the protein was distributed along the erythrocyte membrane and throughout the space between the gamete and the erythrocyte membrane. The mechanism by which Pf155/RESA remained aggregated around the spaces and its role in erythrocyte lysis are unknown. It is of interest that the parasite appeared to use the same molecule during invasion of erythrocytes and during release of gametes from infected erythrocytes.

Animals↗