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Biomedical subjects

N White

Publications and source records attributed to N White.

At least 55 records · Page 3Linked to original sources
PubMed1998

Artesunate versus artemether for the treatment of recrudescent multidrug-resistant falciparum malaria.

The therapeutic efficacy and toxicity of artesunate (2mg/kg/day for five days, then 1 mg/kg/day for two days: total=12 mg/kg) was compared with that of artemether (4 mg/kg followed by 2 mg/kg/day for two days, then 1 mg/kg/day for four days: total=12 mg/kg) for the treatment of recrudescent multidrug-resistant falciparum malaria in an open randomized trial in 443 patients living on the western border of Thailand. Parasite and fever clearance times were similar in both groups; within 48 hr 94% (95% confidence interval [CI]=91-96%]) of the treated patients were aparasitemic and 93% (95% CI=89-96%) were afebrile. Symptom resolution and resolution of hepatomegaly were slightly slower in the artesunate group; adjusted hazards ratio=1.5 (95% CI=1-2.0, P < 0.01) and 2.2 (95% CI=1.4-8, P=0.04), respectively. There was no significant difference in times to resolution or development of anemia or splenomegaly between treatment groups. By day 28, 3% (95% CI=0.3-5%) of the patients treated with artesunate and 6% of those treated with artemether (95% CI = 2-9%) had recurrent infections (P=0.3). Both regimens were very well tolerated, with no significant adverse effects attributable to either derivative. Overall, these data suggest that the two oral artemisinin derivatives are safe, highly effective, and result in equivalent therapeutic responses in the treatment of drug-resistant falciparum malaria.

Adolescent↗
PubMed1997

Interphase nuclei of many mammalian cell types contain deep, dynamic, tubular membrane-bound invaginations of the nuclear envelope.

The nuclear envelope consists of a double-membraned extension of the rough endoplasmic reticulum. In this report we describe long, dynamic tubular channels, derived from the nuclear envelope, that extend deep into the nucleoplasm. These channels show cell-type specific morphologies ranging from single short stubs to multiple, complex, branched structures. Some channels transect the nucleus entirely, opening at two separate points on the nuclear surface, while others terminate at or close to nucleoli. These channels are distinct from other topological features of the nuclear envelope, such as lobes or folds. The channel wall consists of two membranes continuous with the nuclear envelope, studded with features indistinguishable from nuclear pore complexes, and decorated on the nucleoplasmic surface with lamins. The enclosed core is continuous with the cytoplasm, and the lumenal space between the membranes contains soluble ER-resident proteins (protein disulphide isomerase and glucose-6-phosphatase). Nuclear channels are also found in live cells labeled with the lipophilic dye DiOC6. Time-lapse imaging of DiOC6-labeled cells shows that the channels undergo changes in morphology and spatial distribution within the interphase nucleus on a timescale of minutes. The presence of a cytoplasmic core and nuclear pore complexes in the channel walls suggests a possible role for these structures in nucleo-cytoplasmic transport. The clear association of a subset of these structures with nucleoli would also be consistent with such a transport role.

3T3 Cells↗
PubMed1997

The influence of the full blood count on medical inpatient management.

AIM: This investigation studied the use of the full blood count (FBC) in a general medical inpatient ward at Groote Schuur Hospital. OBJECTIVES: To determine the relative frequency of the reasons for which FBCs were requested (clinically indicated v. routine) and how they influenced patient management. PATIENTS: One hundred and sixty-five consecutive general medical inpatients admitted to the ward between September and December 1993 were included. Each patient underwent an FBC and differential white cell count prior to entering the ward. DESIGN: After taking a history and examining the patient, the physician responsible for each of the 165 patients completed a questionnaire. OUTCOMES MEASURED: Physicians had to indicate whether the FBC was routine or clinically indicated and how the FBC result influenced their patient management. RESULTS: In 67.9% of cases the FBC was considered to be clinically indicated, while in 32.1% of cases it was routine. Although it was felt that 76.4% of the clinically indicated tests influenced patient care, patient management was changed in only 24.7% of cases. In the case of routine tests, care was influenced in only 2.0% of cases. CONCLUSION: Routine tests have a very low clinical yield. There is no substitute for good clinical judgement and the practice of routine tests must be reviewed, as much time, money and patient discomfort could be saved by the elimination of unnecessary investigations.

Blood Cell Count↗
PubMed1996

A guide to spirometry as applied to occupational health.

In the context of occupational health, spirometric testing of respiratory function has a number of important applications. These applications can be expected to become more widespread in view of extensive changes to occupational health and compensation legislation in South Africa. Spirometry is an essential component of pre-assignment medical examinations at the commencement of employment; of medical surveillance of workers exposed to hazardous substances so as to intervene when early changes in pulmonary function are detected; of medical evaluation of functional impairment for appropriate job relocation or compensation; and of research. These applications of spirometry each have special considerations which are detailed.

Female↗
PubMed1995

Nutritional response in a Drosophila yolk protein gene promoter.

The yolk protein genes (yps) of Drosophila melanogaster are only expressed in the ovary and fat body of female flies if they are supplied with proteinaceous food. This nutritional response is specific to the yp genes. We have used transgenic flies transformed with a series of constructs bearing deletions in the upstream region of the yp1 and yp2 genes attached to a reporter gene to search for DNA sequences responsible for the nutritional induction specific for yp1 and yp2 genes. Several regions were shown independently of each other to confer nutritional regulation on the expression of the yp1 and yp2 genes. This regulation can be induced both on the yp promoter and the heterologous Drosophila heat-shock 70 (hsp 70) promoter. The redundancy of sequences conferring a nutritional response on the yp genes is similar to that observed for the female specificity of these genes and suggest that several DNA binding proteins interact to provide the correct regulation of these genes. These results suggest that nutrition acts to modify the level of a trans-acting factor in the fat body. Northern blot analysis showed that the transcript levels from the dsx gene are not affected by nutrition, indicating that the response is not mediated via the dsx gene.

Alcohol Dehydrogenase↗
PubMed1995

Preventing the nosocomial transmission of tuberculosis.

OBJECTIVE: To study the efficacy of expanded tuberculosis infection control measures consisting primarily of administrative controls. DESIGN: Descriptive case series. SETTING: University-affiliated, inner-city hospital. INTERVENTIONS: Introduction of expanded tuberculosis infection control measures (including an expanded respiratory isolation policy). MEASUREMENTS: The number of tuberculosis exposure episodes and skin test conversion rates of health care workers were measured before and after implementation of expanded infection control measures. Tuberculosis exposure episodes (the number of patients who were not placed in respiratory isolation at admission but who subsequently had a diagnosis of acid-fast bacilli smear-positive pulmonary tuberculosis during that admission or within 2 weeks of discharge) were compared for two time periods: the 8 months before and the 28 months after implementation of infection control measures. Tuberculin skin test conversion rates among health care workers were evaluated during a 2.5-year period. RESULTS: After expanded infection control measures were implemented, the number of tuberculosis exposure episodes decreased from 4.4 per month (35 episodes among 103 patient admissions for potentially infectious tuberculosis over 8 months) to 0.6 per month (18 episodes among 358 patient admissions for smear-positive pulmonary tuberculosis over 28 months) (odds ratio, 9.72; 95% CI, 4.99 to 19.25 [P < 0.001]). The cumulative number of days per month that potentially infectious patients with tuberculosis were not in isolation decreased from 35.4 to 3.3 (P < 0.001). A concomitant decrease in tuberculin skin test conversion rates in health care workers was seen; 6-month tuberculin skin test conversion rates decreased steadily from 3.3% (118 conversions in 3579 health care workers; 1/92 to 6/92), 1.7%, 1.4%, 0.6%, to 0.4% (23 conversions in 5153 workers [1/94 to 6/94]) (P < 0.001). CONCLUSIONS: Infection control measures effectively prevented nosocomial transmission of tuberculosis to health care workers. Administrative controls appear to be the most important component of a tuberculosis infection control program and should be the first focus of such a program, especially at public hospitals, where resources are most likely to be limited.

Adult↗
PubMed1995

An investigation of differences between three age groups in verbal and spatial task performance using the dual-task paradigm.

A dual-task paradigm with concurrent verbal and spatial tasks was used to investigate differences across three age groups for lateralized effects, magnitude of tapping interference, and cognitive task output. In addition, rescaled scores comparing verbal with spatial measures within and across age groups were analyzed to examine asymmetric age differences for right versus left hemisphere abilities. Results of the present dual task finger tapping investigation of three age groups showed all groups left lateralized for verbal tasks and right lateralized for spatial tasks. However, the magnitude of interference in tapping was significantly greater in paced nonideational shadowing tasks and during paced purposeful spatial tasks. Outcomes of exploratory analyses suggest a complex interplay between aptitude and the corresponding lateralized effects and cognitive effort to perform the task.

Adolescent↗
PubMed1995

Characterization of 20q deletions in patients with myeloproliferative disorders or myelodysplastic syndromes.

Deletions of the long arm of chromosome 20 are associated with several myeloid malignancies. We have analyzed the structure of the del(20q) in 30 patients and two cell lines. Twenty-one of the patients presented with a myeloproliferative disorder and nine with a myelodysplastic syndrome. Two categories of deletions were identified. Eighteen patients had a large deletion with loss of both G(+) bands from the long arm of chromosome 20. Twelve patients had small deletions with loss of one G(+) band from the long arm of chromosome 20. A chromosome paint was generated from a del 20q marker carrying a small deletion. This probe was hybridized to normal metaphases (reverse chromosome painting) and also to metaphases from patients with a del 20q (comparative reverse chromosome painting). All six small deletions analyzed were characterized by loss of the proximal G(+) band (q12) and retention of the distal G(+) band (q13.2). These data define a minimal deleted region extending from 20q11.2-20q13.1.

Adult↗
PubMed1995

Facilitation of acetylcholine release and cognitive performance by an M(2)-muscarinic receptor antagonist in aged memory-impaired.

Aged memory-impaired (AI) and unimpaired (AU) 24-25-month-old Long-Evans rats were used to investigate the integrity of various cholinergic markers during normal aging and to establish if alterations can possibly relate to cognitive disabilities. AI and AU rats were classified on the basis of their performance in the Morris swim maze task. Choline acetyltransferase activity (ChAT) was not differentially altered in various cortical and hippocampal areas between these two groups. Similarly, quantitative receptor autoradiography did not reveal significant differences in 3H-pirenzepine/muscarinic M1 and 3H-hemicholinium-3/high-affinity choline uptake binding sites in AI versus AU rats. In contrast, 3H-AF-DX 384/putative muscarinic M2 binding was significantly increased in certain cortical and hippocampal areas of the age-impaired animals. These increments were correlated with decreased in vivo acetylcholine (ACh) release capacity in the AI rats. Most interestingly, the muscarinic M2 antagonist BIBN-99 reversed, in a dose-dependent manner, the impaired ACh release as well as the cognitive deficits observed in the AI group. Similarly, BIBN-99 reversed scopolamine-induced amnesia in young animals. The efficacy of BIBN-99 likely relates to its antagonistic properties on negative muscarinic M2 autoreceptors that are apparently increased in the AI animals, leading to altered ACh release. Taken together, these findings strengthen the role of ACh in learning and memory and may have implications for the treatment of degenerative disorders associated with impaired cholinergic functions, such as Alzheimer's disease.

Acetylcholine↗
PubMed1994

A follow-up dual-task investigation of lateralized effects in right- and left-handed males.

A dual-task follow-up investigation examined the influence of sample size and ideational complexity of cognitive tasks on lateralized effects. With a larger sample (n = 128), results showed a "manual dominance effect" for relaxed and paced nonideational vocalized tasks. A hierarchy of ideational verbal tasks yielded the expected lateralized effects which corresponded with increasingly greater interference in concurrent tapping, but not in strength of laterlized effect. Instead of a trend seen in the earlier work (Steiner, Green, & White, 1992), results revealed a significant difference between handedness groups for one complex spatial task. Finally, outcomes for the other spatial task highlight the importance of assessing tradeoffs in attention.

Adult↗
PubMed1994

A comparison of tympanic thermometer readings to pulmonary artery catheter core temperature recordings.

The purpose of this study was to determine the accuracy of FirstTemp (Intelligent Medical Systems, Carlsbad, CA) tympanic thermometer readings compared with core body temperatures obtained via pulmonary artery catheter (PAC). Five measurements were obtained on 19 cardiovascular surgery patients. Tympanic thermometer measurements tended to be higher than PAC measurements. However, most of the differences were not clinically significant. Differences found between right and left ear measurements were most likely due to poor measurement technique. When the correct technique is used, nurses can be confident that tympanic temperature readings are clinically accurate.

Aged↗
PubMed1994

Degradation of 1,4-dioxane by an actinomycete in pure culture.

An actinomycete capable of sustained aerobic growth on 1,4-dioxane was isolated from a dioxane-contaminated sludge samples. The actinomycete, CB1190, grows on 1,4-dioxane as the sole carbon and energy source with a generation time of approximately 30 h. CB1190 degrades 1,4-dioxane at a rate of 0.33 mg of dioxane min-1 mg of protein-1 and mineralizes 59.5% of the dioxane to CO2. CB1190 also grows with other cyclic and linear ethers as the sole carbon and energy sources, including 1,3-dioxane, 2-methyl-1,3-dioxolane, tetrahydrofuran, tetrahydropyran, diethyl ether, and butyl methyl ether. CB1190 is capable of aerobic autotrophic growth on H2 and CO2.

Actinomycetales↗
PubMed1993

DNA fingerprint analysis of a free-range koala population.

Thirty-six koalas in a free-range Queensland population were fingerprinted using an M13 probe in combination with MspI digestion. The technique was found to be highly repeatable, with estimates of 0.1-1.6% within-gel error and 0.1-2.5% between-gel error. Of the 43 different-size fingerprint bands produced in the population, only 2 bands were common to all 36 koalas. Ten bands were quite rare, occurring at a frequency of 0.2 or less. All 36 koalas had unique DNA fingerprints (probability of 1.88 x 10(-7)), which enabled them each to be uniquely identified. Despite this, there was still a high level of band sharing in the population (mean number of shared bands = 0.749). This level is much higher than that reported for humans, birds, cats, dogs, and cattle but not as high as that reported previously for Victorian koalas. This lack of genetic variation may influence the ability of the population to respond to stress situations, such as lack of food, habitat destruction, and disease.

Animals↗