Search PubMed⌕ Search

Biomedical subjects

P Newton

Publications and source records attributed to P Newton.

At least 19 recordsLinked to original sources
PubMed2000

Parasite multiplication potential and the severity of Falciparum malaria.

The multiplication rates and invasiveness of Plasmodium falciparum parasites isolated from adult Thai patients hospitalized with uncomplicated malaria (n=34) were compared with those from persons with severe malaria (n=42). To simulate severe malaria and control for host effects, the in vitro cultures were adjusted to 1% parasitemia and used the same red blood cell donor. P. falciparum isolates from persons with severe malaria had initial cycle multiplication rates in vitro that were 3-fold higher than those from uncomplicated malaria (median [95% confidence interval], 8.3 [7. 1-10.5] vs. 2.8 [1.7-3.9]; P=.001). Parasites causing severe malaria exhibited unrestricted red blood cell invasion, whereas those from uncomplicated malaria were restricted to a geometric mean of 40 (31%-53%) of red blood cells. P. falciparum parasites causing severe malaria were less selective and multiplied more at high parasitemias than those causing uncomplicated malaria.

Animals↗
PubMed2000

Antimalarial bioavailability and disposition of artesunate in acute falciparum malaria.

The pharmacokinetic properties of oral and intravenous artesunate (2 mg/kg of body weight) were studied in 19 adult patients with acute uncomplicated Plasmodium falciparum malaria by using a randomized crossover design. A sensitive bioassay was used to measure the antimalarial activity in plasma which results from artesunate and its principal metabolite, dihydroartemisinin. The oral study was repeated with 15 patients during convalescence. The mean absolute oral bioavailability of the antimalarial agent in patients with acute malaria was 61% (95% confidence interval [CI], 52 to 70%). The absorption and elimination of oral artesunate were rapid, with a mean elimination half-life of antimalarial activity of 43 min (95% CI, 33 to 53 min). Following oral administration to patients with acute falciparum malaria, peak antimalarial activity in plasma and the area under the plasma concentration-time curve were approximately double those during convalescence and the apparent volume of distribution and clearance were approximately half those during convalescence (P < or = 0.005). Acute malaria is associated with a significant reduction in the clearance of artesunate-associated antimalarial activity.

Administration, Oral↗
PubMed1999

Mismatch negativity in the visual modality.

In the auditory system, the automatic detection of stimulus change provides a mechanism for switching attention to biologically significant events. It gives rise to the mismatch negativity (MMN) event related potential. It is unclear whether a similar mechanism exists in vision. To investigate this issue, evoked potentials were recorded to target stimuli in the centre of the visual field, and to frequent standard and infrequent deviant stimuli presented outside the focus of attention, in the peripheral field. Deviants evoked a more negative potential than standards 250-400 ms after the stimulus. The negativity, distributed over supplementary visual areas of occipital and posterior temporal cortex, was associated with the rarity of the deviants and not the physical features which distinguished them from standards. This negativity shares a number of characteristics with auditory MMN.

Adult↗
PubMed1999

Prevalence of hypovitaminosis D in Indo-Asian patients attending a rheumatology clinic.

This study was performed to determine the prevalence of hypovitaminosis D (HD) and hypovitaminosis D associated with secondary hyperparathyroidism (HD-SHPT) among Indo-Asians attending rheumatology clinics in Wolverhampton. A cross-sectional survey of 98 clinic attenders and 36 normal controls subjects was undertaken. The groups were matched for age, gender, and body mass index. There was a high prevalence of vegetarianism, and milk consumption was low in both groups. Clinical scores for musculoskeletal pain, gait, and muscle strength were all significantly worse in clinic attenders (p < 0.001). Comparing clinic attenders with controls, 25-OH-vitamin D levels were 6.6 +/- 3.9 vs. 8.2 +/- 4.8 microg/L (p < 0.01) and the prevalence of HD (<8 microg/L) was 78% vs. 58% (p < 0.05), but neither parathyroid hormone levels (53 +/- 60 vs. 50 +/- 18 ng/L, n.s.) nor HD-SHPT prevalence (22% vs. 33%, n.s.) were significantly different. Routine biochemical tests were not discriminant, but none of the controls and 10 of 98 (10%) clinic attenders had elevated alkaline phosphatase levels: 6 with HD and 3 with HD-SHPT. Vitamin D deficiency has an extremely high prevalence among Indo-Asians in the U.K., particularly in those attending rheumatology clinics. Detection of HD and HD-SHPT is only possible using measurements of 25-OH-vitamin D and PTH.

Alkaline Phosphatase↗
PubMed1999

Think before you speak: pauses, memory search, and trace redintegration processes in verbal memory span.

Immediate memory span and speed of memory search were assessed for words and nonwords of short and long spoken duration. Memory span was substantially greater for words than for nonwords and for short than for long items, though speed of memory search was unaffected by either length or lexicality. An analysis of the temporal pattern of responses in the memory span task indicated that inter-item pauses were longer between nonwords than words but that these pause durations were unaffected by item length. A model of verbal short-term memory span is described in which trace selection from a short-term store and the redintegration (restoration) of degraded phonological traces both occur in the pauses between saying successive items. Both trace selection and trace redintegration appear to play important roles in accounting for individual differences in memory span.

Adolescent↗
PubMed1999

The presentation and management of female breast symptoms in general practice in Sheffield.

BACKGROUND: Relatively little is known about the incidence of breast symptoms in primary care consultations and GPs' patterns of referral to secondary care. OBJECTIVE: We aimed to identify the consultation rate for breast symptoms in general practice and to describe the management of those symptoms, including patterns of referral to secondary care. METHOD: Prospective data were collected by 248 GPs concerning 508 women consulting for breast symptoms. A verification study was carried out in nine practices to compare the data collected prospectively with information recorded contemporaneously in the same patients' notes. Main outcome measures were number of patients with lump, pain, nipple discharge, skin or nipple problems, family history or other symptoms at first or subsequent consultation, management action, age of patient and number of patients meeting study criteria for whom GPs did not record information in the prospective study. RESULTS: The mean number of consultations per GP over the 4-week recording period was 2.05. However, examination of a patient's notes from a sample of nine practices participating in the verification study suggested that GPs recorded only slightly over half of the consultations for breast symptoms on the study pro forma. At their first consultation, 40% of women presented with a breast lump and 40% with breast pain. Fifty-eight per cent of women with lumps were referred for specialist evaluation after a first or subsequent consultation, whereas the comparable percentage for women referred for pain was 17%. CONCLUSIONS: At an initial consultation for breast symptoms, GPs refer approximately one-third of women to secondary care. Women are most likely to be referred for a lump or for a family history of breast cancer and least likely to be referred for breast pain. The verification study suggests that relying on GPs to collect data on a specific group of patients may produce an underestimate of the consultation rates for a specified condition.

Adolescent↗
PubMed1999

Chronic inhalation carcinogenicity study of commercial hexane solvent in F-344 rats and B6C3F1 mice.

The carcinogenic and chronic toxicity potential of commercial hexane solvent was evaluated in F-344 rats and B6C3F1 mice (50/sex/concentration/species) exposed by inhalation for 6 h/day, 5 days/week for 2 years. Target hexane vapor concentrations were 0, 900, 3000, and 9000 ppm. There were no significant differences in survivorship between control and hexane-exposed groups, and clinical observations were generally unremarkable. Small, but statistically significant decreases in body weight gain were seen in rats of both sexes in the mid- and high-exposure groups and in high-expsoure female mice. The only noteworthy histopathological finding in rats was epithelial cell hyperplasia in the nasoturbinates and larynx of exposed groups. This response was judged to be indicative of upper respiratory tract tissue irritation. No significant differences in tumor incidence between control and hexane-exposed rats were found. In mice, uterine tissue from the high-exposure females exhibited a significant decrease in the severity of cystic endometrial hyperplasia compared to controls. An increase in the combined incidence of hepatocellular adenomas and carcinomas was observed in high-exposure female mice. The incidence of liver tumors was not increased in the mid- or low-exposure female mice or in male mice exposed to hexane. An increased incidence of pituitary adenomas was observed in female, but not male mice. This finding was not believed to have been treatment-related because the incidence in the control group was unusually low, and the incidence in exposed groups was not dose-related and was within the historical control range. No other neoplastic changes judged to be treatment-related were observed in tissues from male or female mice. In conclusion, chronic exposure to commercial hexane solvent at concentrations up to 9000 ppm was not carcinogenic to F-344 rats or to male B6C3F1 mice, but did result in an increased incidence of liver tumors in female mice.

Adenoma, Liver Cell↗
PubMed1999

Malaria: new developments in treatment and prevention.

Malaria still kills some 0.5-2.5 million people per year in the tropics. Resistance to the cheap, most commonly used antimalarials continues to spread alarmingly and could outpace drug development. The artemisinin derivatives have had an important clinical impact both on the treatment of resistant falciparum malaria and on the incidence of disease in low-transmission areas. A few promising new antimalarials are being tested clinically but there is an imperative need for cheap, well-tolerated drugs that can be used in short courses, and for strategies to delay the onset of drug resistance. Bed nets have been shown to reduce the incidence of severe malaria in many areas but an effective vaccine is urgently needed.

Antimalarials↗
PubMed1998

Well-being and treatment satisfaction in older people with diabetes.

OBJECTIVE: To measure well-being and treatment satisfaction and their correlates in older people with diabetes. RESEARCH DESIGN AND METHODS: A postal survey was conducted of 1,000 diabetic patients aged > or = 60 years, representing 56% of the resident older diabetic population in an inner-city health district with a largely indigenous population of 230,000 people and a widely varied socioeconomic mix. Well-being and treatment satisfaction were measured with diabetes-specific instruments and correlated with patient data held in a central register. RESULTS: There was an 81% response. The general well-being scores (median [interquartile range]) for patients on diet alone, tablets, and insulin were 54 (44-60), 53 (42-61), and 48 (35-56) (P < 0.001 comparing insulin with diet and tablets) compared with a scale maximum of 66. Treatment satisfaction scores were 35 (31-36), 35 (32-36), and 34 (30-36) (P < 0.001 comparing insulin with diet and tablets), scale maximum 36. Mean HbA1c concentrations were 5.0 +/- 1.4% (for patients on diet alone), 5.8 +/- 1.6% (tablets), and 6.6 +/- 1.7% (insulin) (P < 0.001 for each difference). Neither well-being nor treatment satisfaction correlated with HbA1c. Insulin-treated patients were younger and had been diabetic longer than non-insulin-treated patients; their well-being remained slightly, but significantly, lower when adjusted for age, sex, BMI, and diabetes duration, but treatment satisfaction was no longer significantly different. Women had lower well-being than men. CONCLUSIONS: It has proved possible to measure well-being and treatment satisfaction in a large community-based samples of older people with diabetes. At the level of glycemic control in this population, neither parameter correlated with HbA1c. The lower well-being in insulin-treated patients remained significant in multivariate analysis.

Aged↗
PubMed1997

Long-term follow-up in outpatient clinics. 1: The view from general practice.

BACKGROUND: Nearly three-quarters of patients seen in specialist outpatient clinics in England are in follow-up. It has been suggested that the care of many of these patients could be transferred to general practice. OBJECTIVES: We aimed to estimate the proportion of patients in general practice who are in long-term outpatient follow-up, and to identify GPs' perspectives on the appropriateness and implications of the discharge of their patients to primary care. METHOD: Prevalence data were collected by identifying correspondence from outpatient clinics to GPs in four Manchester practices (population 29,000). GPs were asked to assess the suitability for discharge of their patients who were seen in medical outpatient clinics. Semi-structured interviews were carried out with 15 of these GPs, and with 11 GPs who had patients recently discharged from medical clinics. RESULTS: At least 4.5% of the practice populations were in long-term outpatient follow-up (median duration 25 months). These patients had consulted their GP a median of seven times during the previous year. GPs were willing to take over the care of 48% of patients in medical clinics, and in many cases did not expect that this would lead to an increase in their workload. Some resource needs were identified in general practice, and improvements to the process of discharge were suggested. CONCLUSION: The need for continued follow-up in outpatient clinics should be reviewed. Many patients could be discharged without increasing GPs' workload. For more complex cases, additional resources may be needed to provide co-ordinated care within general practice. When patients are discharged, GPs need information quickly and need access to specialist advice for their patients when necessary without long delays.

Ambulatory Care Facilities↗
PubMed1997

Bovine surfactant therapy for patients with acute respiratory distress syndrome.

Lung surfactant is deficient in patients with acute respiratory distress syndrome (ARDS). We performed a randomized, prospective, controlled, open-label clinical study of administration of a bovine surfactant to patients with ARDS to obtain preliminary information about its safety and efficacy. Patients received either surfactant by endotracheal instillation in addition to standard therapy or standard therapy only. Three different groups of patients receiving surfactant were studied: patients receiving up to eight doses of 50 mg phospholipids/kg, those receiving up to eight doses of 100 mg phospholipids/kg, and those receiving up to four doses of 100 mg phospholipids/kg. Outcome measures included ventilatory support parameters, arterial blood gases, organ system failures, bronchoalveolar lavage (BAL) analyses, immunologic analyses, survival, and adverse events during the 28-d study period. Fifty-nine study patients were evaluable; 43 in the surfactant group and 16 in the control group. The FI(O2) at 120 h after treatment began was significantly decreased only for patients who received up to four doses of 100 mg phospholipids/kg surfactant as compared with control patients (p = 0.011). Mortality in the same group of patients was 18.8%, as compared with 43.8% in the control group (p = 0.075). The surfactant instillation was generally well tolerated, and no safety concerns were identified. This pilot study presents preliminary evidence that surfactant might have therapeutic benefit for patients with ARDS, and provides rationale for further clinical study of this agent.

Adult↗
PubMed1996

Psittacosis associated with bilateral 4th cranial nerve palsies.

We report a 55-year-old man who presented with a moderately severe community acquired pneumonia due to Chlamydia psittaci, probably acquired from budgerigars. One of his presenting symptoms was diplopia, secondary to bilateral 4th cranial nerve palsies, which persisted for some months. The literature on neurological complications of pneumonia is reviewed.

Chlamydophila psittaci↗
PubMed1995

Fluctuations in nucleus accumbens dopamine concentration during intravenous cocaine self-administration in rats.

Fluctuations in extracellular dopamine and DOPAC levels in nucleus accumbens septi (NAS) were monitored in 1-min microdialysis samples taken from rats engaged in intravenous cocaine self-administration. For four rats the dose per injection was fixed at 2.0 mg/kg; for four others the dose per injection was varied irregularly, from one response to the next, between three levels (0.5, 1.0 and 2.0 mg/kg). Regardless of the dosing regimen, extracellular dopamine levels were tonically elevated by 200-800% within the cocaine self-administration periods, fluctuating phasically within this range between responses. In the fixed dose condition, the phasic increases following each injection (and the phasic decreases preceding them) averaged approximately 50% of the mean tonic elevation. Phasic fluctuations in dopamine levels remained time-locked to lever-presses even when response rate was irregular, because of the variable dose condition. In the variable dose condition greater increases in dopamine and longer inter-response times followed injections of the higher doses; dopamine fluctuations were consistent with the multiple-infusion pharmacokinetics of cocaine. DOPAC levels showed a slow tonic depression during cocaine self-administration, but individual injections were not associated with discernible phasic fluctuations of DOPAC. These data are consistent with the hypothesis that falling dopamine levels trigger successive responses in the intravenous cocaine self-administration paradigm, but inconsistent with the notion that extracellular dopamine levels are depleted at the times within sessions when the animal initiates drug-seeking responses.

3,4-Dihydroxyphenylacetic Acid↗