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N C Abbot

Publications and source records attributed to N C Abbot.

At least 19 recordsLinked to original sources
PubMed1999

Randomized, double-blind trial of chitosan for body weight reduction.

BACKGROUND: Overweight and obesity is a prevalent and costly threat to public health. Compelling evidence links overweight and obesity with serious disorders such as cardiovascular diseases and diabetes. Dietary regimen are notoriously burdened with poor compliance. Chitosan is promoted in the US and other countries as an oral remedy to reduce fat absorption and has now been incorporated as a major constituent into several over-the-counter remedies. The primary aim of this study is to investigate the clinical effectiveness of oral chitosan for body weight reduction. METHODS: Thirty-four overweight volunteers were included in a randomized placebo-controlled double-blind trial. Subjects were assigned to receive either four capsules of chitosan or indistinguishable placebo twice daily for 28 consecutive days. Measurements were taken at baseline, after 14 and 28d of treatment. Subjects maintained their normal diet and documented the type and amount of food consumed. Adverse effects were assessed and compliance monitored. RESULTS: Data from 30 subjects were entered into an intention-to-treat analysis. After four weeks of treatment, body mass index, serum cholesterol, triglycerides, vitamin A, D, E and beta-carotene were not significantly different in subjects receiving chitosan compared to those receiving placebo. Vitamin K was significantly increased after four weeks in the chitosan group compared with placebo (P<0.05). Compliance was 91.5% and 96.0% for chitosan and placebo groups respectively. CONCLUSION: The above data suggest that chitosan in the administered dosage, without dietary alterations, does not reduce body weight in overweight subjects. No serious adverse effects were reported.

Adolescent↗
PubMed1998

Different standards for reporting ADRs to herbal remedies and conventional OTC medicines: face-to-face interviews with 515 users of herbal remedies.

AIMS: To determine whether adverse drug reactions (ADRs) to herbal remedies would be reported differently from similar ADRs to conventional over-the-counter (OTC) medicines by herbal-remedy users. METHODS: Face-to-face interviews (using a structured questionnaire) with 515 users of herbal remedies were conducted in six pharmacy stores and six healthfood stores in the UK. The questionnaire focused on the likely course of action taken by herbal-remedy users after experiencing an ADR associated with a conventional OTC medicine and a herbal remedy. RESULTS: Following a 'serious' suspected ADR, 156 respondents (30.3%) would consult their GP irrespective of whether the ADR was associated with the use of a herbal remedy or a conventional OTC medicine, whereas 221 respondents (42.9%) would not consult their GP for a serious ADR associated with either type of preparation. One hundred and thirty-four respondents (26.0%) would consult their GP for a serious ADR to a conventional OTC medicine, but not for a similar ADR to a herbal remedy, whereas four respondents (0.8%) would consult their GP for a serious ADR to a herbal remedy, but not for a similar ADR to a conventional OTC medicine. Similar differences were found in attitudes towards reporting 'minor' suspected ADRs. CONCLUSIONS: Consumers of herbal remedies would act differently with regard to reporting an ADR (serious or minor) to their GP depending on whether it was associated with a herbal remedy or a conventional OTC medicine. This has implications for herbal pharmacovigilance, particularly given the increasing use of OTC herbal remedies. The finding that a high proportion of respondents would not consult their GP or pharmacist following ADRs to conventional OTC medicines is also of concern.

Adult↗
PubMed1996

Sympathetic vasomotor dysfunction in leprosy patients: comparison with electrophysiological measurement and qualitative sensation testing.

Testing of skin vasomotor reflexes (VRs) by laser Doppler flowmetry (LDF) is now a recognised method of measuring peripheral dysautonomia. To assess its specificity as an indicator of impairment to unmyelinated autonomic fibres, VR testing at the fingerpulp was compared with standard qualitative sensation (QST) and with sensory electrophysiological (SNVC) measurements in 39 Iranian leprosy patients. There was a significant relationship between VR and SNCV values (but not QST): these were jointly measurable in 38.5% of fingers, and jointly absent in 35.3% of fingers which also showed significantly reduced LDF perfusion and skin temperatures. However, in 10.3% of fingers, predominantly index and otherwise apparently healthy, VRs were absent but SNCV present, suggesting early sub-clinical autonomic impairment. In a further 16% of fingers, predominantly ulnar and with poor microcirculation, intact (though impaired) VRs could be recorded despite the absence of SNCV responses, suggesting sparing or regeneration of these fibres. This evidence suggests that where there is heterogeneity of nerve damage a combination of VR and electrophysiological testing can indicate the functional status of distinct fibre types.

Adolescent↗
PubMed1996

Laser Doppler perfusion imaging of skin blood flow using red and near-infrared sources.

At present, scanning laser Doppler imaging uses a 633-nm helium-neon laser (RED) as the only light source, but this restricts its ability to measure blood flow (i) at darkly pigmented skin and (ii) from deeper or subdermal structures. Because near-infrared (NIR) light is known to penetrate deeper into tissue and to be less absorbed than RED, two imagers were adapted to include a NIR laser diode source (one of 830 nm for UK studies; one of 780 nm for leprosy field trials) in parallel with the existing RED source. In human hands representing a range of skin pigmentations, RED scans were unobtainable at the darkest areas of skin, but intact NIR scans could be collected in all cases. In experiments at the rat knee and the dorsal human hand, NIR and RED values were similar on normal skin. Over underlying vessels, however, NIR values greatly exceeded RED values, an effect abolished by occlusion. Similarly, in patients with leprosy and in healthy controls in Spain, fingerpulp NIR values exceeded RED values to the greatest degree when thermoregulatory flow was highest, i.e., when the deeper-lying arteriovenous anastomoses were open. Over areas of experimental inflammation, NIR gave higher values and also exhibited a greater degree of spatial heterogeneity than RED. We conclude that some current limitations of laser Doppler imaging technology can be overcome by the use of NIR laser diode sources.

Adult↗
PubMed1995

Effects of treatment on the histopathology of leprosy.

AIMS: To identify the histological changes in leprosy skin lesions over the first few weeks after the start of leprosy treatment and to examine their relationship to reversal reaction. METHODS: Sequential skin biopsy during treatment with multiple drug therapy. In this study, a series of 28 patients was studied, from whom two or more biopsies were taken at two week intervals. Fourteen patients had paucibacillary leprosy (PBL) and 14 had multibacillary leprosy (MBL). RESULTS: In most cases, granuloma fraction and bacterial index fell during treatment, the bacterial index being less sensitive than the granuloma fraction. Since the biopsies were fixed in buffered formalin and processed through to paraffin wax, little immunohistochemistry was feasible. However, there was strong evidence of immune activation, with increased expression of HLA-DR in the granulomas of MBL and PBL cases: the epidermis also expressed HLA-DR in several patients. Such changes may reflect gamma IFN production from granuloma lymphocytes. Patients with reversal reaction often showed HLA-DR expression on admission which decreased with corticosteroid treatment. CONCLUSIONS: The results suggest that activation of cell mediated immunity in leprosy lesions occurs during treatment with multiple drug therapy and may not be restricted to those with clinical evidence of reversal reaction.

Adolescent↗
PubMed1994

Effect of hyperoxia at 1 and 2 ATA on hypoxia and hypercapnia in human skin during experimental inflammation.

Transcutaneous PO2 and PCO2 measurements and estimates of skin respiration were monitored at different levels of inspired PO2 in 20 healthy adults during the first 4 days of the tuberculin reaction, a convenient model of acute inflammation. Hyperoxia at 1 and 2 ATA significantly increased transcutaneous PO2 levels in undisturbed and in inflamed skin but did not fully correct the relative hypoxia at the site of inflammation. Hypercapnia was reduced with O2 breathing at 2 ATA. The apparent rate of O2 consumption at the reaction site was raised during hyperoxia, most prominently at 2 ATA. The most intense reactions showed a central relative slowing of laser-Doppler blood flow indicative of microcirculatory impairment. The extent of the relative hypoxia and hypercapnia was greatest in these strongest reactions. The density of lymphocytes and monocytes in biopsies of 48-h reactions was loosely related to the corresponding transcutaneous PO2 measurements. The present study provides evidence that diffusion barriers, in addition to increased local respiration, can contribute to the apparent hypoxia and hypercapnia of this inflammatory model.

Adult↗
PubMed1994

Circulation and sensation at the fingertips of claw hands.

Measurements of skin blood flow (by laser Doppler flowmetry) and temperature were made under environmental conditions promoting peripheral vasodilatation at the fingertips of a disfigured 'clawed' hand in 12 leprosy patients long-resident at Baba Baghi Leprosy Hospital, Tabriz, Iran. Sensory function was assessed by measuring the responses to light touch, pain and temperature of each finger, and peripheral autonomic function was gauged by estimating palmer sweating and by measuring skin vasomotor reflexes in response to inspiratory gasp. In 2 patients all measured fingers had laser Dopper flux (LDFlux) values and skin temperatures lower than the 95% confidence limits for the mean of 20 healthy controls, i.e. were impaired; in 2 patients all fingers had normal values for LDFlux and temperature; and in 8 patients there was a combination of impairment with most fingers normal for these parameters but with the small finger most commonly impaired. There were 10 (67%) fingers with impaired LDFlux and temperature values who had significant sensory impairment, whereas only 5 (18%) of the fingers with normal LDFlux values and temperatures had a similar sensory deficit. Overall, the fingers with the most impaired sensation had significantly (P < 0.05) lower LDFlux and temperature values than those with no sensory deficit. Microcirculatory impairment was not related to disordered skin vasometer reflexes or dysfunction of sweating. We concluded that the relationship between motor (skeletal muscle) nerve paralysis and any subsequent sensory neuropathy and/or microcirculatory impairment is more complex than might be expected from previous understanding of the disease.

Adult↗
PubMed1993

Dynamic thermographic imaging for estimation of regional perfusion in the tuberculin reaction in healthy adults.

A sensitive method for measurement of the volume of blood flow through the skin, based on the kinetics of reheating after localised cooling, is described in this paper. This method has been used to study the tuberculin reaction as a model of cutaneous delayed-type hypersensitivity (DHS) in man. Over the positive reaction there is accelerated reheating similar in kinetics and extent to that seen after maximal hyperaemia induced by intradermal injection of histamine or prostaglandin E2. The earlier phase of reheating (10-100 s) is more dependent on blood flow, whereas the later phase (100-300 s) is apparently more dependent on non-perfusion heat exchange mechanisms, including conduction. The reheat kinetic method is largely dependent on blood flow in the deep dermal vessels (diameter > 50 microns), whereas the alternative approach of measurement of the velocity of flow of erythrocytes in the microcirculation by laser Doppler (LD) flowmetry gives results biased towards the most superficial dermal circulation. Previous studies with LD flowmetry have shown that the blood velocity is greatest at the centre of weak and strong reactions, while in the most intense reactions it is raised at the centre but maximal at the periphery (central relative slowing, CRS) raising the possibility of central ischaemia. The reheat kinetics approach has now indicated that the deep dermal circulation is not impaired in CRS reactions. It is concluded that there must be partial obstruction of the parts of the microcirculation communicating between the deep and superficial dermal plexuses, presumably from the accumulation of exudate oedema in the most intense tuberculin reactions.

Adult↗
PubMed1993

Vasomotor reflexes in the fingertip skin of patients with type 1 diabetes mellitus and leprosy.

Fingertip skin blood flow was measured by laser Doppler flowmetry (as LDflux) under environmental conditions promoting vasodilation in Scottish patients with diabetes mellitus and Indian patients with leprosy. The reflex control of fingertip blood flow was assessed by measuring the reduction in LDflux induced by deep inspiratory gasp (IG) and cold challenge (CC) of immersing the contralateral hand in cold water. The uncomplicated diabetic patients showed normal vasomotor reflexes and an increased, though non significant, LDflux level (p < 0.06). The patients with diabetic neuropathy had resting LDflux levels significantly less than the uncomplicated group and also had substantial impairment of both IG and CC reflexes. Those with retinopathy (but no clinically apparent neuropathy) had LDflux within the normal range, but they showed minor evidence of impairment of the vasomotor reflexes. The uncomplicated newly registered leprosy patients had reduced LDflux and substantial impairment of CC reflexes. These changes were more marked in newly registered leprosy patients with clinical evidence of neuropathy. Leprosy patients with long-standing neuropathy requiring orthopaedic treatment had LDfluxes so greatly reduced that measurement of vasomotor reflexes was not practicable. The CC reflex was more severely affected than the IG reflex and more frequently absent in leprosy patients, possibly because of associated sensory neuropathy affecting the afferent limb of this response. Thus laser Doppler flowmetry can detect impairment of reflex control of fingertip blood flow in both diabetes mellitus and leprosy, but there are functional differences in the pattern of autonomic impairment between the diseases, suggesting differences in the pathogenesis of nerve damage.

Adult↗
PubMed1993

A preliminary assessment of laser Doppler perfusion imaging in human skin using the tuberculin reaction as a model.

Laser Doppler imaging is a new development in the field of laser Doppler flowmetry. We were recently loaned the Lisca laser Doppler perfusion imager (LDI) manufactured by Lisca Development, Linkoping, Sweden for assessment against other methods for assessment of skin perfusion. In order to evaluate the device, it was applied to imaging flux changes induced in human skin during the tuberculin reaction. Flux values were compared directly with those from conventional lightguide laser Doppler flowmetry, and parameters measured using two other methods for assessment of tissue perfusion, dynamic thermographic imaging and tissue spectrophotometry. The results showed very good correlations between the various methods. In addition, the LDI showed that very large differences in flux values (up to 5 V) could be found within distances of only 2 mm during the tuberculin reaction and that focal centres of low flux values surrounded by higher values ('craters') could be found not only at the centre, but elsewhere in the lesion. The LDI enables rapid non-invasive detailed analysis of blood flow patterns in skin and correlates well with other methods for measuring skin perfusion. Its use to examine heterogeneity of microvascular blood flow patterns may lead to further understanding of the local mechanisms for regulation of oxygen supply to tissue.

Female↗
PubMed1993

Biological zero in laser Doppler measurements in normal, ischaemic and inflamed human skin.

The Biological Zero (BZ) signal in laser Doppler flowmetry was recorded during temporary occlusion of the arterial circulation to the limb by a blood pressure cuff inflated suprasystolically for 2 min. The non-thermoregulatory skin at the ankle was compared with the thermoregulatory skin over the toe pad in patients with lower limb arterial obstructive disease, elderly controls without arterial disease and young healthy adults under cool (15-17 degrees C) and warm (25-27 degrees C) ambient conditions. The absolute BZ values did not differ significantly within the three groups at the two room temperatures. However the resting laser Doppler flowmetry signal (LDflux) was consistently higher under warm than cold room temperatures: these differences were much greater at the toe than at the ankle. Accordingly, the relative size of BZ, expressed as a percentage of the resting LDflux, was least over the toe in a warm room (5-10%) and greatest over the malleolus (59-83%) in the cold room. The changes during the evolution of a positive tuberculin skin reaction were followed as a model of chronic inflammation in man. The resting LDflux rose 10 fold (from 0.3 to 3.4V) while the change in the BZ was minor (0.16-0.2V). Thus the rise in LDflux in a fully developed tuberculin reaction was approximately 30X greater than that for the corresponding BZ. Concurrent measurements of the alternative output from the laser Doppler flowmeter (CMBC) showed in a similar pattern. Since the BZ signal can be a substantial proportion of the resting LDflux measurement, we support the recommendation that the BZ should be measured wherever possible and practicable, for subtraction from the observed LDflux to assess the true flow: 'raw' LDflux measurements should be interpreted with extreme caution, particularly at relatively low resting LDflux levels.

Adolescent↗