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Biomedical subjects

S Horton

Publications and source records attributed to S Horton.

At least 19 recordsLinked to original sources
PubMed2004

Experience with the Jostra Rotaflow and QuadroxD oxygenator for ECMO.

Since April 1988, we have been able to offer extracorporeal membrane oxygenation (ECMO) to patients who are either failing ventilation or who need cardiopulmonary support following cardiac surgery. During this time, we have supported 211 patients, the majority of whom have been supported with the Avecor (Affinity, Avecor Cardiovascular Inc., Minneapolis, MN, USA) spiral wound silicone-membrane oxygenator. Microporous hollow-fibre oxygenators have been used (18%) at our center. However, due to their early failure, they have necessitated conversion to a device that potentially would last for the entire ECMO course, i.e., Avecor and, subsequently, have not been used routinely until the introduction of the QuadroxD (Jostra Medizintechnik AG, Hirrlingen, Germany). The recent development of the poly-4-methyl-1-pentene diffusion membrane allows us to utilize hollow-fibre technology with a true (nonmicroporous) membrane. This has enabled us to use this low-resistance device with all its inherent advantages, without plasma leakage necessitating circuit changeover. From July 2000, we have used the QuadroxD oxygenator for our patients requiring ECMO support. This has been in patients with weights ranging from 2.16-51.0 kg (n = 23), with the longest support being for 1119 hours. This new technology has enabled us to utilize a single device for all patient sizes, so we now have an ECMO circuit set up at all times, minimizing the time required for support to be available, potentially improving survivor morbidity.

Cardiac Surgical Procedures↗
PubMed2004

Pump-induced haemolysis: a comparison of short-term ventricular assist devices.

Centrifugal pumps are superior to roller pumps for extended support durations in terms of pump-induced haemolysis. In this study, we evaluated the commonly used Biomedicus BP 50 and compared it with the Jostra Rotaflow and a standard roller pump in an in vitro test circuit. Each circuit was run for a six-day period and repeated five times. Plasma haemoglobin values showed the roller pump to become more haemolytic than the Biomedicus (p = 0.022) and the Rotaflow. A statistically significant difference between the Biomedicus and the Rotaflow was observed on day six of the trial (p = 0.016), with the Rotaflow showing lower levels of haemolysis than the Biomedicus. These results support the use of the new generation centrifugal pump, the Rotaflow, as a suitable device for short-term ventricular assist.

Assisted Circulation↗
PubMed2003

East African running dominance revisited: a role for stereotype threat?

Regardless of the possible existence of physiological advantages in East African runners, belief that such differences exist creates a psychological atmosphere that can have significant consequences on performance. This is known as stereotype threat and can feature in many sports.

Africa, Eastern↗
PubMed2001

Neurogenin2 expression in ventral and dorsal spinal neural tube progenitor cells is regulated by distinct enhancers.

The basic helix-loop-helix transcription factor Neurogenin2 (NGN2) is expressed in distinct populations of neural progenitor cells within the developing central and peripheral nervous systems. Transgenic mice containing ngn2/lacZ reporter constructs were used to study the regulation of ngn2 in the developing spinal cord. ngn2/lacZ transgenic embryos containing sequence found 5' or 3' to the ngn2 coding region express lacZ in domains that reflect the spatial and temporal expression profile of endogenous ngn2. A 4.4-kb fragment 5' of ngn2 was sufficient to drive lacZ expression in the ventral neural tube, whereas a 1.0-kb fragment located 3' of ngn2 directed expression to both dorsal and ventral domains. Persistent -gal activity revealed that the NGN2 progenitor cells in the dorsal domain give rise to a subset of interneurons that send their axons to the floor plate, and the NGN2 progenitors in the ventral domain give rise to a subset of motor neurons. We identified a discrete element that is required for the activity of the ngn2 enhancer specifically in the ventral neural tube. Thus, separable regulatory elements that direct ngn2 expression to distinct neural progenitor populations have been defined.

Animals↗
PubMed2001

Commentary on "evidence that iron deficiency anemia causes reduced work capacity".

This commentary assesses the strength of the causal evidence presented by Haas and Brownlie in this supplement and examines the potential magnitude of iron-deficiency anemia on welfare. From both the laboratory and field experiments, the evidence is strong and suggests that the potential magnitude of the effect of iron-deficiency anemia on work productivity is substantial. This commentary briefly discusses some of the limitations of using the estimates of effects on physiological capacity for measuring the effect on the social and economic well-being of individuals and society. Biological data are relevant to social and economic development, but additional field studies may be as important as the laboratory experiments to answer questions that also affect work productivity, household maintenance and child raising activities, and hence affect social and economic development. We extend the critical evidence review of human field studies that received disproportionately less attention than the laboratory studies in Haas and Brownlie. We provide some estimates of the magnitude of effects on well-being based on how this information has been used. Future field studies that examine the effect of iron-deficiency anemia and work output in an economic sense should measure increases in productivity but should complement this information with data on wages, income or some measure of profits to derive a money metric measure of increased productivity. Additional information on individual time allocation in household work, child care and leisure may also be required to capture social benefits deriving from improved work capacity.

Anemia↗
PubMed2001

Trends in diet, nutritional status, and diet-related noncommunicable diseases in China and India: the economic costs of the nutrition transition.

Undernutrition is being rapidly reduced in India and China. In both countries the diet is shifting toward higher fat and lower carbohydrate content. Distinct features are high intakes of foods from animal sources and edible oils in China, and high intakes of dairy and added sugar in India. The proportion of overweight is increasing very rapidly in China among all adults; in India the shift is most pronounced among urban residents and high-income rural residents. Hypertension and stroke are relatively higher in China and adult-onset diabetes is relatively higher in India. Established economic techniques were used to measure and project the costs of undernutrition and diet-related noncommunicable diseases in 1995 and 2025. Current WHO mortality projections of diet-related noncommunicable diseases, dietary and body composition survey data, and national data sets of hospital costs for healthcare, are used for the economic analyses. In 1995, China's costs of undernutrition and costs of diet-related noncommunicable diseases were of similar magnitude, but there will be a rapid increase in the costs and prevalence of diet-related noncommunicable diseases by 2025. By contrast with China, India's costs of undernutrition will continue to decline, but undernutrition costs did surpass overnutrition diet-related noncommunicable disease costs in 1995. India's rapid increase in diet-related noncommunicable diseases and their costs projects similar economic costs of undernutrition and overnutrition by 2025.

China↗
PubMed1999

A phase I/II study of the safety and pharmacokinetics of nevirapine in HIV-1-infected pregnant Ugandan women and their neonates (HIVNET 006).

OBJECTIVE: To determine the safety, pharmacokinetics, tolerance, antiretroviral activity, and infant HIV infection status after giving a single dose of nevirapine to HIV-1-infected pregnant women during labor and their newborns during the first week of life. DESIGN: An open label phase I/II study. SETTING: Tertiary care hospital, Kampala, Uganda. PATIENTS AND INTERVENTIONS: Nevirapine, 200 mg, was given as a single dose during labor to 21 HIV-1-infected pregnant Ugandan women. In cohort 1, eight infants did not receive nevirapine whereas in cohort 2, 13 infants received a single dose of nevirapine, 2 mg/kg, at 72 h of age. OUTCOMES: The number and type of adverse events; nevirapine concentrations in the plasma and breast milk; maternal plasma HIV-1 RNA copy number before and up to 6 weeks after delivery; and HIV-1 infection status of the infants were monitored. RESULTS: Nevirapine was well tolerated by women and infants; no serious adverse events that were related to nevirapine were observed. Median nevirapine concentration in the women at delivery was 1623 ng/ml (range 238-2356 ng/ml); median cord/maternal blood ratio of 0.75 (0.37-0.93). The median half-life in women was 61.3 h (27-90 h) and the transplacental nevirapine half-life in infants who did not receive a neonatal dose was 54 h. The median half-life after a single dose at 72 h in infants was 46.5 h. During the first week of life, the median colostrum/breast milk to maternal plasma nevirapine concentration was 60.5% (25-122%). The median nevirapine concentration in breast milk 1 week after delivery was 103 ng/ml (25-309 ng/ml). Plasma nevirapine concentrations were above 100 ng/ml in all infants from both cohorts tested at age 7 days. Maternal HIV-1 RNA levels decreased by a median of 1.3 logs at 1 week postpartum, and returned to baseline by 6 weeks postpartum. Detectable plasma HIV-1 RNA was observed in one out of 22 (4.5%) infants at birth; three out of 21 (14%) at 6 weeks; and four out of 21 (19%) at 6 months of age. CONCLUSION: The administration of a single dose of nevirapine to women during labor and to their newborns at 72 h was well tolerated and showed potent antiretroviral activity in the women at 1 week after dosing without rebound above baseline 6 weeks after a single dose. The nevirapine concentration was maintained above the target of 100 ng/ml in infants at age 7 days, even in those infants not receiving a neonatal dose. This regimen has promise as prophylaxis against intrapartum and early breast milk transmission in a breastfeeding population.

Anti-HIV Agents↗
PubMed1999

Safety and toxicity of nonoxynol-9 gel as a rectal microbicide.

BACKGROUND AND OBJECTIVES: Methods of HIV and STD prevention, which can be controlled by the receptive partner, are a high priority for research and development. Studies on the safety of Nonoxynol-9 (N-9) on the vaginal mucosa have yielded conflicting results. No Phase I study has evaluated the effect of N-9 on the rectal mucosa. GOALS: To assess the safety of 52.5 mg of N-9 in a 1.5-g gel when applied one to four applicators per day to the rectum and penis. STUDY DESIGN: The study included 25 HIV-negative and 10 HIV-positive, monogamous gay male couples in which each partner was exclusively insertive or receptive while using N-9 gel. Each participant served as his own control during placebo gel use compared to during N-9 gel use. Receptive partners underwent anoscopic examination after 1 week of placebo use and after 2, 5, and 6 weeks of N-9 gel use, with rectal biopsies obtained after 1 week of placebo use and after 5 and 6 weeks of N-9 gel use. Insertive partners had safety monitoring after 1 week of placebo use and after 2, 5, and 6 weeks of N-9. RESULTS: No rectal ulcers were detected; superficial rectal erosions were noted in two HIV-negative participants. Abnormal or slightly abnormal histologic abnormalities of rectal biopsies were detected in 31 (89%) receptive participants after N-9 gel use compared to 24 (69%) participants after 1 week of placebo gel use. Meatal ulceration, not caused by herpes simplex virus, was detected in one HIV-negative participant. CONCLUSION: Low-dose N-9 gel was not associated with macroscopic rectal and penile epithelial disruption or inflammation, but histologic abnormalities were commonly observed during N-9 gel as well as during placebo gel use.

Adult↗
PubMed1999

Spiny keratoderma--a demonstration of hair keratin and hair type keratinization.

Six cases of spiny keratoderma were analyzed with hair specific antikeratin antibodies (AE13, AE14) and by electron microscopy. The keratotic column exhibited a different keratin birefringence and the underlying viable epidermis was less eosinophilic than the surrounding epidermis. AE13, which is specific for hair cortex, was positive in the lower column and variably positive in the viable epidermis, often beyond the columnar lesion. AE14 was negative in the lesion. Electron microscopy demonstrated features of keratinization of normal hair cortex, i.e. by the accretion of keratin filaments without production of keratohyalin or trichohyalin granules. Cementsomes (lamellar granules) and marginal bands were not produced as they are not formed in normal cortical keratinization. It was suggested that spiny keratoderma represents an ectopic hair formation of palms and soles.

Aged↗
PubMed1999

Preoperative and postoperative considerations for carbon dioxide laser resurfacing.

Cutaneous laser resurfacing is a tremendous advance in the treatment of photoaged skin. With the recent developments in laser technology, the procedure has become widely utilized among many physician subspecialists. The latest laser systems permit controlled vaporization of skin so that most novice operators feel comfortable with the technique in a short period of time. Nevertheless, there are many issues that need to be addressed before performing the procedure. First, not every person is an appropriate candidate for laser resurfacing. Second, both the physician and the patient must be aware of the preoperative preparation and prolonged postoperative care involved with the procedure. Finally, the physician must be able to identify and treat, and the patient must be educated about, the side effects and potential complications associated with the procedure. It is only by addressing these issues that the clinical results obtained by CO2 laser resurfacing can be maximized.

Female↗
PubMed1998

Is anyone speaking my language?

This paper describes an on-going three-phase action research project undertaken by members of the Norwich Community Trust speech and language therapy adult services team. With the support of the Clinical Audit department the project was set up in order to: 1) investigate the characteristics, needs and aspirations of the population of dysphasic people in the community; 2) examine how dysphasic people and their families perceive the speech and language therapy service; 3) implement specific changes to the speech and language therapy service to dysphasic people and their families. These changes are based on proposals developed through a working partnership between the speech and language therapy department and dysphasic people and their families.

Adult↗
PubMed1998

Hypertext markup language as an authoring tool for CD-ROM production.

The Hypertext Markup Language (HTML) used to create Web pages is an attractive alternative to the proprietary authoring software that is now widely used to produce multimedia content for CD-ROMs. This paper describes the advantages and limitations of HTML as a non-proprietary and cross-platform CD-ROM authoring system, and the more general advantages of HTML as data standard for biocommunications content.

Authorship↗
PubMed1996

Persistent vegetative state: what decides the cut-off point?

Advances in medicine and technology have allowed us early and effective diagnosis and treatment of many disease processes, with new and developing interventions ensuring this progression. However, in some illnesses and conditions, despite appropriate treatment, deterioration in the person's condition ensues. This may occur following a cardiopulmonary arrest, where resuscitation may have been 'successful' at the time, but the brain has suffered irreversible anoxic damage. It has been seen that only 10-25% of patients survive to discharge following a cardiac arrest (Broadway 1993), and the consequences of cardiopulmonary resuscitation can not only be costly but can leave the patient in a persistent vegetative state (PVS). PVS, however, does not confine itself to these patients alone, and can present following other cerebral traumas, including head injuries. This is therefore especially pertinent to intensive care nurses, who may find themselves caring for such patients in a critical care setting. Growing public awareness of this altered health state due, for instance, to the Tony Bland case in the UK in 1993, has highlighted a need for greater knowledge of the consequences of the condition and the proposed management of patients in PVS. This paper attempts to describe the course of this syndrome, and considers some of the ethical and moral issues surrounding the care and treatment of patients with PVS. The issues surrounding euthanasia are briefly explored together with the attitudes of those caring for these patients.

Critical Care↗