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Biomedical subjects

M Nelson

Publications and source records attributed to M Nelson.

At least 271 records · Page 15Linked to original sources
PubMed1994

Iron-deficiency anaemia and physical performance in adolescent girls from different ethnic backgrounds.

One hundred and fourteen 11-14-year-old schoolgirls from Wembley, Middlesex, were assessed for Fe status (haemoglobin (Hb), packed cell volume and mean corpuscular Hb concentration, height, weight, eating habits, and ethnic origin, and undertook a step test to assess physical performance. Overall, 20% of girls had Hb less than 120 g/l, ranging from 11% in White girls to 22-25% in girls of Asian origin. Prevalence of low Hb was 20% in vegetarians, higher in White vegetarians compared with non-vegetarians (23 v. 4%), but lower in the Indian vegetarians compared with non-vegetarians (17 v. 32%). Low Hb was present in 25% of girls who had tried to lose weight in the previous year, and was more common in girls from manual social class backgrounds than non-manual (24 v. 10%). At the start of the step test the twenty-three girls with low Hb had heart rates similar to those with normal Hb, but heart rates in the low Hb group were significantly elevated immediately after the step test, and still significantly elevated 1 min later. The present results confirm the findings of a previous study in White girls, and suggest that physical performance may be compromised at mild levels of anaemia.

Adolescent↗
PubMed1994

Food photography. I: The perception of food portion size from photographs.

Fifty-one male and female volunteers aged 18-90 years from a wide variety of social and occupational backgrounds completed 7284 assessments of portion size in relation to food photographs. Subjects were shown six portion sizes (two small, two medium and two large) for each of six foods, and asked to compare the amount on the plate in front of them to (a) a series of eight photographs showing weights of portions from the 5th to the 95th centile of portion size (British Adult Dietary Survey), or (b) a single photograph of the average (median) portion size. Photographs were prepared either in colour or in black and white, and in two different sizes. The order of presentation of foods; use of black and white or colour; the size of photographs; and presentation of eight or average photographs were each randomized independently. On average, the mean differences between the portion size presented and the estimate of portion size using the photographs varied from -8 to +6 g (-4 to +5%) for the series of eight photographs, and from -34 to -1 g (-23 to +9%) for the single average photograph. Large portion sizes tended to be underestimated more than medium or small portion sizes, especially when using the average photograph (from -79 to -14 g, -37 to -13%). Being female, 65 years and over, or retired, or seeing photographs in colour, were all associated with small but statistically significant overestimations of portion size. Having a body mass index > or = 30 kg/m2 was associated with an 8% underestimate of portion size. We conclude that use of a series of eight photographs is associated with relatively small errors in portion size perception, whereas use of an average photograph is consistently associated with substantial underestimation across a variety of foods.

Adolescent↗
PubMed1994

Effect of site-specific modification on restriction endonucleases and DNA modification methyltransferases.

Restriction endonucleases have site-specific interactions with DNA that can often be inhibited by site-specific DNA methylation and other site-specific DNA modifications. However, such inhibition cannot generally be predicted. The empirically acquired data on these effects are tabulated for over 320 restriction endonucleases. In addition, a table of known site-specific DNA modification methyltransferases and their specificities is presented along with EMBL database accession numbers for cloned genes.

Amino Acid Sequence↗
PubMed1994

Rapid detection of Rh(D)- or K-positive fetal red cells in chorion villus samples by a flow cytometric technique.

Rh(D)- and K-negative women who have become severely isoimmunized by pregnancy are at risk of fetal loss or damage in subsequent pregnancies. A flow cytometric method is described whereby the presence of Rh(D) or K antigen on fetal erythrocytes may be determined using chorion villus samples taken during the first trimester. This method has the advantage of speed and sensitivity with results being available within 2 h. Decisions as to management of the pregnancy or termination may thus be made with minimal delay.

Chorionic Villi Sampling↗
PubMed1994

Management of pulmonary aspergillosis in AIDS: an emerging clinical problem.

AIMS: To review the clinical, radiographic, and therapeutic features of 11 cases of respiratory Aspergillus infection in patients with AIDS. METHODS: All induced sputum and bronchoalveolar lavage samples obtained from HIV seropositive patients between January 1985 and March 1993 were analysed for Aspergillus species. Additionally, where appropriate, bronchial or renal biopsy specimens, or both, were taken before treatment had started. RESULTS: In 11 patients Aspergillus fumigatus was identified in alveolar samples obtained by sputum induction. This was confirmed by bronchoalveolar lavage in eight. Three patients had Aspergillus plaques in the trachea and bronchus, while a fourth patient had an aspergilloma. Risk factors for Aspergillus infection were present in all patients, including corticosteroid treatment in three cases and neutropenia in four, three of whom had received chemotherapy for Kaposi's sarcoma. Four patients had concomitant cytomegalovirus infection. Ten patients had a CD4 count of less than 50 cells/mm3 while one patient had a disseminated T cell lymphoma with a CD4 count of 242 cells/mm3. Of the three patients with samples obtained by sputum induction who did not undergo bronchoscopy, two had a normal chest x ray picture and the third had a right lobar pneumonia complicating an aggressive lymphoma. All three were treated with itraconazole 200 mg twice a day without further investigation. Survival from the time of diagnosis of Aspergillus infection was short: seven patients died within six weeks, although only one death was directly attributed to pulmonary aspergillosis. At six monthly follow up, one patient, who initially had a positive Aspergillus culture from bronchial washings and a normal chest radiograph, developed a renal aspergilloma despite the disappearance of Aspergillus sp from the sputum. CONCLUSION: Pulmonary aspergillosis is an important clinical problem in patients with AIDS with a CD4 count of less than 50 cells/mm. Furthermore, patients with Aspergillus sp in sputum induction or bronchial washings may develop disseminated disease despite adequate treatment of the primary infection.

AIDS-Related Opportunistic Infections↗
PubMed1994

Advance patient directives: assessing the alternatives.

Whereas the Patient Self-Determination Act is a significant step in the right direction, there are ethical, legal, and medical questions yet unresolved. In this second installment of a three-part series, the authors describe the options available to patients.

Advance Directives↗
PubMed1994

Advance patient directives: are they worth it?

The Patient Self-Determination Act became effective in December 1991. After two complete years of experience, data are emerging to indicate how implementation of the Act has affected the issues of patient autonomy and cost containment. In this third article of a series on advance directives, the authors conclude that the preliminary results of their study are consistent with other studies recently completed that demonstrate the favorable effect of the Act on enhancing patient autonomy and containing the costs of health care. The authors suggest a basic study design for replication and adaptation by others, encourage more uniformity by researchers in future studies to more precisely measure the effect of the Act, and briefly describe the expansion of their continuing study.

Advance Directives↗
PubMed1994

Biosphere science news roundup. Biosphere 2 completes first two year closure experiment

On September 26, 1993 Biosphere 2 completed it's first two year experiment which included eight "Biospherians." Now that the first experiment is concluded the results can be examined and reported. Future issues of the journal will include more in depth peer reviewed articles on the experiment while this article will give a brief overview. The facility is now between experiments and is undergoing minor upgrades in preparation for the next ten and a half month enclosure scheduled for March 1994. The new crew has been chosen and is "moving in" now. Now that an interval of time has passed since September 26, 1993 and the end of the initial two year closure of Biosphere 2 it is appropriate to take stock of initial accomplishments and problem areas.

Animals↗
PubMed1994

Development of a flow cytometric test for the detection of D-positive fetal cells after fetomaternal hemorrhage and a survey of the prevalence in D-negative women.

A sensitive test for the presence of D-positive fetal red blood cells (RBCs) in the maternal circulation of D-negative women has been developed. It was used to investigate the possibility that the occasional failure in preventing alloimmunization might be due to the administration of inadequate amounts of prophylactic anti-D Rh immune globulin. The standard dose in Australia contains 125 microg of antibody, and can suppress immunization by an estimated 6 mL of packed D-positive RBCs. A fetomaternal hemorrhage (FMH) of this volume is detectable in the maternal circulation as approximately 0.25 percent of the total RBCs. Our test utilizes a commercially available human monoclonal IgG anti-D that has been biotinylated and used with a dye-conjugated streptavidin. Flow cytometry is used to quantitate fluorescing D-positive RBCs. To date, 2,288 tests have been performed on blood samples from D-negative women attending local antenatal clinics or at the time of delivery. Evidence for an FMH has been obtained in six cases (0.26%). In one case, the FMH was only 0.1 percent, and in another (confirmed by the Kleihauer-Betke method), fetal cells constituted only 0.2 percent. Additional Rh immune globulin was not given to these patients. In the other four cases, the D-positive fetal cells were estimated to be 0.7,0.5,0.5, and 0.4 percent, and additional prophylactic Rh immune globulin was administered. Although the prevalence of FMH is low, screening D- negative women at risk of alloimmunization has proved to be simple, fast, and inexpensive.

Journal Article↗
PubMed1994

P-31 magnetic resonance spectroscopy of skeletal muscle in the eosinophilia-myalgia syndrome: a preliminary study.

OBJECTIVE: To determine the pathogenesis of muscular symptomatology in the eosinophilia-myalgia syndrome (EMS). METHODS: P31-nuclear magnetic resonance spectroscopy (MRS) was performed on 7 patients with EMS and 10 age matched controls to determine the relative concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), and adenosine triphosphate (ATP) in calf muscle. RESULTS: Patients with EMS had statistically lower ATP/PCr ratios and higher Pi/ATP ratios than controls, indicating a preferential and unique decrease in ATP levels at rest in skeletal muscle. CONCLUSION: Skeletal muscle is metabolically abnormal in patients with EMS. This abnormality may contribute to the myalgia, spasm, and weakness seen in this disorder.

Adenosine Triphosphate↗
PubMed1993

Polysplenia syndrome and congenital short pancreas.

We present a report of a stillborn female of mixed ancestry with congenitally short pancreas, polysplenia, congenital heart defect, normal bronchial branch pattern, and interruption of the inferior vena cava to add to the growing numbers (15) of this malformation complex in the literature. Additional manifestations were congenital hydrocephalus and absence of intestinal malrotation. A recent poster presentation at the Second International Workshop on Fetal Genetic Pathology in Montana by Drut et al. underlined the importance of reporting these cases and of the pathological examination required ["Abnormal Spleen Lobulation and Short Pancreas," in Blastogenesis-Normal and Abnormal. New York: Wiley-Liss, Inc. for the National Foundation-March of Dimes, 1993].

Abnormalities, Multiple↗
PubMed1993

Sequencing two DNA templates in five channels by digital compression.

By applying algebraic coding methods to the Sanger dideoxynucleotide procedure, DNA sequences of two templates can be determined simultaneously in only five reactions and data channels. A 5:2 data compression is accomplished by instantaneous source coding of nucleotide sequence pairs into one set of 5-bit block codes. A general algebraic expression, 2n-1 > or = 4f, describes conditions under which f DNA templates can be sequenced using n channels. Such compression sequencing is accurate and efficient, as demonstrated by manual 35S autoradiographic detection and automated on-line analysis using fluorescent-labeled primers. Symmetric 5:2 compression is especially useful when comparing two closely related sequences.

Automation↗
PubMed1993

Detection of Chlamydia trachomatis in urine using enzyme immunoassay and DNA amplification.

The suitability of urine specimens for the detection of Chlamydia trachomatis infections in men was assessed. Urethral swabs from 301 patients were cultured for C. trachomatis, and the results were compared with results obtained from Chlamydiazyme. The results of 298 specimens were also compared with results obtained from PCR analysis of first-void urine specimens. The sensitivity of confirmed Chlamydiazyme analysis was 93% and the specificity was greater than 99% compared with culture. The sensitivity of the PCR method was 100% compared with culture. Chlamydia trachomatis was detected by PCR in an additional three specimens from which C. trachomatis could not be cultured. Urine appears to be an appropriate specimen for the detection of C. trachomatis antigens and nucleic acids.

Adolescent↗